Sildalis

By Q. Amul. Vanderbilt University.

Precautons Elderly purchase sildalis pills in toronto, children and young adults; hepatc impairment (Appendix 7a); renal impairment (Appendix 7d); pregnancy (Appendix 7c); may mask underlying disorders such as cerebral irritaton; avoid for 3-4 days afer gastrointestnal surgery; lactaton (Appendix 7b); interactons (Appendix 6a); Parkinson’s disease; epilepsy; depression; porphyria; driving or operatng machines; hypertension; cirrhosis; congestve heart failure purchase sildalis 120mg online. Dose Oral Preventon of post-operatve nausea and vomitng: Adult 16 mg buy sildalis 120 mg with visa, 1 h before inducton of anaesthesia order sildalis amex. Nausea and vomitng associated withcancer chemotherapy: Adult- 24 mg as a single dose taken 30 min before start of single day chemotherapy. Child (4-11 yrs)- 4 mg tablets 3 tmes a day; contnue for 1-2 days afer completon of chemotherapy. Adverse Efects Headache, constpaton or diarrhoea, dizziness; fushing, hypersensitvity reacton, anaphylaxis/anaphylactoid reactons, angioedema; bronchospasm, hypotension, laryngeal edema, urtcaria, hiccups, oculagyric crisis. Dose Oral and intravenous injecton Adult- Nausea, vomitng acute atack: initally 20 mg then 20 mg every 2 h. Adult- Labyrinthine disorder: 5 mg 3 tmes daily increased to 30 mg daily in divided doses that decrease afer meal to 5 to 10 mg daily. Most antpsychotcs are best avoided during pregnancy; hypersensitvity; prolactn dependant tumors. Cauton is also required in severe respiratory disease and in patents with a history of jaundice or who have blood dyscrasias (perform blood counts if unexplained infecton or fever develops). Cauton should be taken in elderly, who are partcularly susceptble to postural hypotension and to hyper- or hypothermia in very hot or cold weather. Serious consideraton should be given before prescribing these drugs for elderly patents. As photosensitsaton may occur with higher dosages, patents should avoid direct sunlight; extrapyramidal syndrome; pregnancy (Appendix 7c); interactons (Appendix 6a). Adverse Efects Less sedatng; extrapyramidal symptoms, partcularly dystonias, more frequent; respiratory depression may occur in suscep- tble patents; amenorrhoea; blurred vision; cholestatc jaundice; neuroleptc malignant syndrome; leucopenia; agranulocytosis. Moton sickness, preventon: 20 to 25 mg at bedtme on night before travel, repeated on day of travel if necessary. Child- Moton sickness, preventon; 2 to 5 years: 5 mg at night and on day of travel, if necessary. Precautons Prostatc hypertrophy; urinary retenton; glaucoma; hepatc disease (Appendix 7a); epilepsy; elderly and children (more susceptble to adverse efects); lactaton (Appendix 7b); pregnancy (Appendix 7c); interactons (Appendix 6a). May impair ability to perform skilled tasks, for example operatng machinery, driving. Adverse Efects Drowsiness, dizziness, sedaton (but para- doxical stmulaton may occur, especially with high doses or in children and eld- erly); headache, psychomotor impairment; urinary retenton, dry mouth, blurred vision, gastrointestnal disturbances; hypersensitv- ity reactons, rashes, photosensitvity reac- tons; jaundice; blood disorders; cardiovas- cular adverse efects-afer injecton; venous thrombosis at site of intravenous injecton; pain on intramuscular injecton; somnolence; tortcollis; tnnitus; leucopenia; thrombocy- topenia, agranulcytosis; apnoea; angioneu- rotc edema. It is transmited by the faeco-oral route and infecton is usually caused by ingeston of cysts from contaminated food and drink. In non-endemic areas, sympto mless carriers should be treated with a luminal amoebicide which will reduce the risk of transmission and protect the patent from invasive amoe- biasis. Diloxanide furoate is most widely used, but other compounds, including clefamide, etofamide and teclozan, are also efectve. Treatment with diloxanide furoate is regarded as successful if stools are free of E. Symptomatc (invasive) amoebiasis may be classifed as intestnal or extra-intestnal. Intestnal amoebiasis is either amoebic dysentery or non-dysenteric amoebic colits. Extra- intestnal amoebiasis most commonly involves the liver, but may involve the skin, genito-urinary tract, lung and brain. Invasive amoebiasis is more likely in malnutriton, immu- nosuppression and pregnancy. Amoebic dysentery may take a fulminatng course in late pregnancy and the puer- perium; treatment with metronidazole may be life saving. In less severe infecton, metronidazole should, if possible, be avoided in the frst trimester. All patents with invasive amoebiasis require treatment with a systemically actve compound such as metronidazole, ornidazole and tnidazole followed by a luminal amoebicide in order to eliminate any surviving organisms in the colon. In severe cases of amoebic dysentery, tetracycline given in combinaton with a systemic amoebicide lessens the risk of superinfecton, intestnal perforaton and peritonits. Giardiasis: Giardiasis is caused by Giardia intestnalis and is acquired by oral ingeston of Giardia cysts. Larger epidemics are difcult to eradicate because of the high proporton of sympto mless carriers and because excreted cysts can survive for long periods outside the human host. Trichomoniasis: Trichomoniasis is an infecton of the genito-urinary tract caused by Trichomonas vaginalis and transmission is usually sexual. Patents and their sexual partners should be treated with metronidazole or other nitroimidazole. Diloxanide Furoate* Schedule H Indicatons Amoebiasis (asymptomatc carriers in non- endemic areas; eradicaton of residual luminal amoebae afer treatment of invasive disease with other drugs). Adverse Efects Flatulence; occasionally vomitng, pruritus and urtcaria; furred tongue. Child- 35 to 50 mg/kg body weight in amoebiasis and 10 to 15 mg/kg body weight in giardiasis. Contraindicatons Chronic alcohol dependence; neurological disease, blood dyscrasias, frst trimester of pregnancy. Precautons Disulfram-like reacton with alcohol; hepatc impairment and hepatc encephalopathy (Appendix 7a); pregnancy (Appendix 7c); see also notes above); lactaton (Appendix 7b); clinical and laboratory monitoring in courses lastng longer than 10 days; interactons (Appendix 6a, 6c, 6d); prolonged use may result in fungal or bacterial superinfecton, phenobarbitones, history of seizure disorder. Adverse Efects Nausea, vomitng, unpleasant metallic taste, furred tongue and gastrointestnal distur- bances; rarely, headache, drowsiness, dizzi- ness, ataxia, darkening of urine, erythema multforme, pruritus, urtcaria, angioedema and anaphylaxis; abnormal liver functon tests, hepatts, jaundice; thrombocytope- nia, aplastc anaemia; myalgia, arthralgia; peripheral neuropathy, epileptform seizures; leukopenia on prolonged or high dosage reg- imens; anorexia, glossits, dryness of mouth. Tinidazole Pregnancy Category-C Schedule H Indicatons Amoebiasis, trichomoniasis and giardiasis, anaerobic infectons, necrotsing ulceratve gingivits, bacterial vaginosis, H. Parenteral Bacterial vaginosis and ulceratve gingivits: Adult- 2g as a single dose parenterally. Contraindicatons Hypersensitvity to nitroimidazole derivatves, frst trimester of pregnancy (Appendix 7c), lactaton, blood dyscrasias, porphyria; interactons (Appendix 6a). Benzylpenicillin and phenoxymethylpenicillin are actve against susceptble strains of Gram-positve bacteria and Gram-negatve bacteria, spirochaetes and actnomycetes, but are inactvated by penicillinase and other beta-lactamases. Benzathine benzylpenicillin and procaine benzylpenicillin are long-actng preparatons which slowly release benzylpenicillin on injecton. A range of penicillins with improved stability to gastric acid and penicillinases have been produced by substtuton of the 6-amino positon of 6-aminopenicillanic acid. Cloxacillin is an isoxazoyl penicillin which is resistant to staphylococcal penicillinase. Broad-spectrum penicillins such as ampicillin are acid-stable and actve against Gram-positve and Gram-negatve bacteria, but are inactvated by penicil- linase. Beta-lactamase inhibitors such as clavulanic acid are ofen necessary to provide actvity against beta-lactamases produced by a wide range of both Gram-negatve and Gram- positve bacteria. Cephalosporins are classifed by generaton, with the frst generaton agents having Gram-positve and some Gram- negatve actvity; the second generaton drugs have improved Gram-negatve actvity and the third generaton cephalosporin have a wider spectrum of actvity, although may be less actve against Gram-positve bacteria than frst generaton drugs, but they are actve against Gram-negatve Enterobacteriaceae and Pseudomonas aeruginosa. This rare, but serious adverse efect may result from very high doses or in severe renal failure. Penicillins should not be given by intrathecal injecton because they can cause encephalopathy which may be fatal. Hypersensitvity: The most important adverse efect of penicillins is hypersensi- tvity which causes rashes and, occasionally anaphylaxis, which can be fatal. Allergic reactons to penicillins occur in 1-10% of exposed individuals, while anaphylactc reactons occur in fewer than 0. Individuals with a history of anaphylaxis, urtcaria or rash immediately afer peni- cllin administraton are at risk of immediate hypersensitvity to penicillin. These individuals should not receive penicillin, rather a cephalosporins or another beta-lactam antbiotc may be used. Patents who are allergic to one penicillin will be allergic to them all because the hypersensitvity is related to the basic penicillin structure and about 10% of penicillin-sensitve patents will be allergic to cephalosporins and other beta-lactams. Individuals with a history of a minor rash (a non-confuent rash restricted to a small area of the body) or a rash occurring more than 72 h afer penicillin administraton are possibly not allergic to peni- cillin and in these individuals a penicillin should not be withheld unnecessarily for a serious infecton; however, the possibility of an allergic reacton should be borne in mind and facilites should be available for treatng anaphylaxis. Ampicillin, Amoxycillin, Amoxycillin with Clavulanic Acid and Cloxacillin: Ampicillin is actve against certain Gram-positve and Gram- negatve organisms. It is used to treat a wide range of infec- tons including otts media, respiratory-tract and urinary- tract infectons and gonorrhoea due to susceptble bacteria. However, ampicillin is inactvated by penicillinases including those produced by Staphylococcus aureus and by common Gram-negatve bacilli such as Escherichia coli; many strains of Haemophilus infuenzae, Moraxella catarrhalis, Neisseria gonorrhoeae and Salmonella and Shigella spp. There are geographical variatons in the incidence of resistance and an awareness of local paterns is important.

The decreasing level of bile acid in the gallbladder triggers the liver to synthesize more bile acids from their precursor buy sildalis 120mg with mastercard, cho- lesterol buy sildalis from india. Be- cause the small intestine needs bile acids to emulsify lipids and form chylomicrons 120mg sildalis with visa, absorption of all lipids and lipid-soluble drugs Adverse decreases until the bile acids are replaced discount sildalis 120mg without prescription. Acidic drugs likely to be affected in- paction, vomiting, diar- clude barbiturates, phenytoin, penicillins, cephalosporins, thyroid rhea, and hemorrhoid ir- hormones, thyroid derivatives, and digoxin. Poor absorption of vita- min K can affect prothrombin times significantly, increasing the risk of bleeding. Just don’t give us bile- Fibric acid derivatives sequestering Fibric acid is produced by several fungi. Fenofibrate is hy- drolyzed while gemfibrozil undergoes extensive metabo- lism in the liver. Fibric acid drugs are used primarily to reduce triglyceride levels, especially very-low-density triglycerides, and secondarily to re- duce blood cholesterol levels. Drug interactions • Fibric acid drugs may displace acidic drugs, such as barbitu- rates, phenytoin, thyroid derivatives, and cardiac glycosides. These drugs include atorvastatin, fluvastatin, lovastatin, pravastatin, rosuvas- tatin, and simvastatin. However, plas- ma levels don’t correlate with the drugs’ abilities to lower choles- Adverse terol. Myalgia is the most Drug interactions common musculoskele- • Taking a statin drug with amiodarone, clarithromycin, cy- tal effect, although closporine, erythromycin, fluconazole, gemfibrozil, itraconazole, arthralgia and muscle ketoconazole, or niacin increases the risk of myopathy or rhab- cramps may also occur. It’s moderately bound to plasma proteins; its over- all binding ranges from 60% to 70%. The drug undergoes rapid me- tabolism by the liver to active and inactive metabolites. However, it may work sodilation and cause by inhibiting hepatic synthesis of lipoproteins that contain flushing. Extended- apolipoprotein B-100, promoting lipoprotein lipase activity, reduc- release forms tend to ing free fatty acid mobilization from adipose tissue, and increasing produce less severe fecal elimination of sterols. Nicotinic acid is contraindicated in patients who are hypersen- Nicotinic acid can sitive to nicotinic acid and in those with hepatic dysfunction, ac- cause hepatotoxicity; tive peptic ulcer disease, or arterial bleeding. As the name implies, cholesterol absorption inhibitors inhibit the absorption of cholesterol and related phytosterols from the intes- tine. Adverse reactions to Pharmacokinetics cholesterol Ezetimibe is rapidly and extensively absorbed following oral ad- absorption ministration. It’s primarily metabolized in the small intestine and ex- inhibitors creted by the liver and kidneys. The most common ad- verse reactions include: Pharmacodynamics • fatigue Ezetimibe reduces blood cholesterol levels by inhibiting the ab- • abdominal pain and di- sorption of cholesterol by the small intestine. This leads to a de- arrhea crease in delivery of intestinal cholesterol to the liver, reducing • pharyngitis and sinu- hepatic cholesterol stores and increasing clearance from the sitis blood. Treatment with fenofibrate, a type of fibric acid derivative, would have to proceed cautiously if the patient is also receiving which drug? Fibric acid derivatives cause an increased risk of bleeding when given with an oral anticoagulant. Because increased liver enzyme levels may occur in patients receiving long-term lovastatin therapy, liver function test results should be monitored. A patient diagnosed with hypertension is most likely to be prescribed which class of drugs first? Types of drugs used to treat disorders of the hematologic system include: • hematinic • anticoagulant • thrombolytic. They do so by increasing hemoglobin, the necessary element for oxygen transportation. Iron, vitamin B12, folic acid This section discusses hematinic drugs used to treat micro- cytic and macrocytic anemia—iron, vitamin B12, and folic acid. Iron preparations discussed in this section include ferrous fumarate, ferrous gluconate, ferrous sul- fate, iron dextran, and sodium ferric gluconate complex. Pharmacokinetics (how drugs circulate) Iron is absorbed primarily from the duodenum and upper jejunum of the intestine. Different iron formulations don’t vary in absorp- tion, but they do vary in the amount of elemental iron supplied. Low iron increases absorption The amount of iron absorbed depends partially on the body’s stores of iron. On the oth- er hand, when total iron stores are large, the body absorbs only about 5% to 10% of the iron available. Enteric-coated preparations decrease iron absorption because, It takes about in that form, iron isn’t released until after it leaves the duodenum. Iron is transported by the blood and bound to transferrin, its carri- er plasma protein. About 30% of the iron is stored primarily as he- mosiderin or ferritin in the reticuloendothelial cells of the liver, spleen, and bone marrow. Excess iron is excreted in urine, stool, sweat, and through intestinal cell-sloughing. Pharmacodynamics (how drugs act) Although iron has other roles, its most important role is the pro- duction of hemoglobin. Pharmacotherapeutics (how drugs are used) Oral iron therapy is the preferred route for preventing or treating iron deficiency anemia. It’s used to prevent anemias in children ages 6 months to 2 years because this is a period of rapid growth and development. Pregnant women may need iron supplements to replace the iron used by the developing fetus. To guard against such a reaction, administer an initial test dose before giving a full-dose in- cause acute hypersensi- fusion. To test for drug with end-stage renal disease who are receiving hemodialysis may sensitivity and prevent also receive parenteral iron therapy at the end of their dialysis ses- serious reactions, al- sion. While parenteral iron therapy corrects the iron store defi- ways give a test dose of ciency quickly, it doesn’t correct the anemia any faster than oral iron dextran before be- preparations would. Iron preparations available for parenteral administration are Carefully assess the iron dextran (given by I. Other drug interactions involving iron include: nephrine and standard • Absorption of tetracyclines (demeclocy- emergency equipment cline, doxycycline, minocycline, oxytetracy- readily available. Pharmacokinetics Vitamin B12 is available in parenteral, oral, and intranasal forms. For the body to absorb oral forms of vitamin B12, the gastric mu- cosa must secrete a substance called intrinsic factor. People who Some patients have a deficiency of intrinsic factor develop a special type of ane- lack a crucial mia known as vitamin B -deficiency pernicious anemia. It then travels via the bloodstream to the liver, where 90% of the body’s supply of vitamin B12 is stored. Although hydroxocobalamin is absorbed more slowly from the injection site, its uptake in the liver may be greater than that of cyanocobalamin. Most gets lost With either drug, the liver slowly releases vitamin B12 as needed by the body. About 3 to 8 mcg of vitamin B12 are excreted in bile each day and then reabsorbed in the ileum. Within 48 hours after a vitamin B12 injection, 50% to 95% of the dose is excreted unchanged in urine. Pharmacodynamics When vitamin B12 is administered, it replaces vitamin B12 that the body would normally absorb from the diet. This vitamin is essen- tial for cell growth and replication and for the maintenance of myelin (nerve coverings) throughout the nervous system. Pharmacotherapeutics Cyanocobalamin and hydroxocobalamin are used to treat perni- cious anemia, a megaloblastic anemia characterized by decreased gastric production of hydrochloric acid and intrinsic factor defi- ciency. Intrinsic factor, a substance normally secreted by the pari- etal cells of the gastric mucosa, is essential for vitamin B12 absorp- tion.

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The primary effects usually reach a plateau at T+1:00 (one hour after taking the dose) to T+1:30 order sildalis online, stay there for some two hours purchase sildalis master card, then start tapering gradually best 120mg sildalis. Secondary effects (afterglow) may be felt for days generic 120mg sildalis overnight delivery, and tertiary psychological effects (e. Taking much more than this is likely to induce or increase unwanted side effects without providing additional benefit in return. It is, of course, desirable to hear from your physician that you’re in good overall health before ingesting any powerful substance. The euphoria that it induces can make it easy to ignore bodily distress signals, so be watchful for things like dehydration (drink lots of water or fruit juices! Several reports from England tell of dosed ravers dancing themselves into severe dehydration and heat exhaustion that required hospitalization and in a few cases resulted in death. If you experience any of these symptoms, sit down, rest, and drink some fruit juice, water, or a gatorade-type sports drink. How to extract codeine from pills: The idea behind the following extraction is that acetaminophen and aspirin (I’ll use A/A from now on) are very insoluble in cold water. Codeine phosphate (the most common salt of codeine) is very soluble in water including cold water. The following table explains: Solubility (31C water) Solubility (21C water) Aspirin 1g / 100 ml 1g / 300ml Acetaminophen 1g / 70 ml 1g / 150 ml Codeine 1g / 2. That way you can dissolve 20 tablets in 50ml of hot water, cool the water down to 10C, filter the solution and end up with the same amount of codeine as the tablets contained but only a fraction of the original amount of A/A. Obtain a quantity of tablets containing codeine, check to see if they contain anything other than codeine, caffeine, acetaminophen or aspirin. If they do, and you don’t know whether or not it will be a problem, your best bet is not to use them. You may want to add 2 extra tablets as it is quite likely you will lose some codeine in the procedure. I don’t know if the use of boiling water would destroy any of the codeine but your best bet is not to use it. Some dissolve on contact with water while others need some help dissolving by crushing them. Note : not all of the tablet will dissolve, there are water-insoluble fillers in the tablet and not all of the A/A will dissolve either(which is what we want). Place the solution in a cold bath, I just use some ice cubes in a container of water. You won’t need a thermometer to measure the temperature, just make sure it’s ”cold”. If you wish to speed this up, you can use less water to dissolve the tablets, and add ice chips to cool the mixture faster. Just make sure you don’t add so much ice that you drastically increase the volume of the mixture. You may also want to rinse the solids left over in the filter with some ice-water to extract any remaining codeine. For reasons not yet clear to those of us investigating these things “unofficially,” butane (and perhaps other gas/solvents with similar ultra-low-boiling properties) selectively solvate the desirable fraction(s) of cannabis oils, pulling out only a beautiful amber “honey oil” and leaving the undesirable vegetative oils, waxes, chlorophyll, etc. Even unsmokable shade leaves produce a wonderfully clean and potent gold oil with this method. I have every reason to suspect that this would work splendidly to extract a super-strong and tasty oil from gross, unpalatable “schwag” commercial pot too, and of course, the better grade of herb you put it in, the better the resulting oil. This hole should be correctly sized to snugly receive the little outlet nozzle of your butane can. In the other end cap, drill a group of 5 or 6 small holes clustered in the center (like a pepper shaker). After putting a piece of paper towel or coffee filter inside it for filtration, put the end cap with several holes on one end of the pipe. A lab stand and clamp are ideal for the mounting, but a regular shop clamp or anything that can hold it sturdily is fine. Turn the butane gas can upside down and dispense the gas into the pipe via the single top hole. A spark at this moment would spell disaster since you have basically created an incendiary explosive device that is leaking. When you’ve exhausted the can into the pipe, back off to a nice distance and let it do its thing. When it gets to the bottom (~30 seconds after dispensing), it begins to drain into the receiving vessel. Over approximately five to eight minutes, the butane extract will finish draining from the pipe to the receiving vessel. Maintain caution with the pipe, however, since there is a lot of residual butane still evaporating from within the pipe (notice the stream of fumes coming from the top hole). When it slows down to a drop every few seconds, you can tap on the top hole with your finger and it will help push the last of the liquid butane out (or one can gently blow into the top hole to do the same thing). Being very low-boiling and volatile, the collected butane will likely begin boiling at ambient temperature. The receiving vessel will gradually frost up as the butane cools it down, slowing down its rate of evaporation, but you can speed this up again simply by holding it in your hands. Watch the butane start bubbling madly with the increase in temperature and marvel at its low boiling point. It takes about 20 minutes or so to allow the butane to evaporate, or quicker if you help it along. The best way to collect and store the oil is probably to let all of the butane evaporate off and then redissolve the oil in some anhydrous or high-% alcohol, and then pour this into a vial and let it sit out for a day or two to allow the alcohol to evaporate. Trying to transfer the oil into a small container while it is still solvated by the butane is too risky. I had filled a vial almost all the way to the top and was preparing to drop those last couple drops in, so that cleverly, I could let the last of the butane evaporate from the vial and the oil would all be neatly contained. But when the last drop hit the mother lode in the vial, it changed the temperature of the solution in the vial upward by a hair and it all “superboiled” out of the vial and onto my fingers, which of course startled me and caused me to drop the vial. The final product is a deep yellow-amber oil of the highest quality, incredibly pure and potent. It’s amazing how this method extracts only the good fraction and leaves the junk in the weed. Note also that this oil has a somewhat higher melt/vaporization point than traditional hash oils; the traditional dispensing method (dipping a needle or paper clip in, getting some goop on the end, and warming it with a flame to get it to drip off into your bowl) still works with this stuff, but it seems you have to be more careful with it because it doesn’t heat to liquid state as quickly or in the same manner, and it can more easily be allowed to burn up on your needle. Those who prefer a tincture-like preparation can of course thin the product a little with a bit of warm high-percentage alcohol like Everclear or 90-whatever-% isopropyl, then drop it onto buds or let a joint absorb some, then let the alcohol evaporate. I also observed that unlike hash oil derived from traditional methods, this product is not immediately soluble in room-temp alcohol; it needed to be warmed before it dissolved fully. Method 2: extraction of thc oil from marijuana If you ever had to think twice about lighting up a joint for fear of someone smelling it. If you were ever forced to blow the smoke out a window and pray you don’t reek of weed. The following steps require nothing more than simple, easy to find materials and a little time. Dump the powdered pot into the mason jar and pour in just enough grain alcohol so the weed particles float freely in the mixture. The alcohol should have turned a dark green color and when shaken should form colorful, oily bubbles on top. Place the sturdy cloth over the metal container and press the cloth down to form a funnel. Carefully pour the contents of the mason jar onto the cloth which is in the metal cup. Gather up the edges of the cloth and squeeze the remaining liquid out of the lump of weed into the metal cup. Step 1a You should now have a quantity of dark green liquid in your metal measuring cup. I recommend performing Step 1 a second time immediately after completing it the first time. You now have twice as much liquid in your metal cup upon repeating the first step.

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By prearranging for reports by seven accomplices to be uniformly incorrect on certain trials purchase sildalis on line amex, Asch was able to show a significant tendency for naive subjects to shift toward the incorrect position taken by others purchase genuine sildalis on-line. Blake and Brehm (16) investigated the effect on naive subjects of hearing the recorded responses of five accomplices buy sildalis 120mg without a prescription. Amount of movement reported for the autokinetic task was varied in magnitude sildalis 120 mg free shipping, divergence, and convergence. Pressures created under simulated conditions produced conformity effects apparently similar in character to those created under face-to-face conditions. McConnell and Blake (91) have confirmed this finding, as have Olmstead and Blake (107) for both face-to-face and simulated group conditions. There is evidence that the presence of several other persons giving uniform responses may produce increases in conformity behavior beyond those attributable to the effect of a single other person. The general proposition is that conformity pressures increase with number of other persons present as a negatively accelerated function. Asch (1) varied the number of accomplices giving erroneous reports from one, two, three, four, eight, to sixteen. He reported direct but unequal increments in shifting for increases from one to two to three accomplices but no significant increases for a larger number. Helson (60) arranged for one, two, or three other persons to report their judgments prior to the critical subject. The effect was found to be directly proportional to the number of accomplices giving prior reports. Luchins and Luchins (89) report that, of the group judging after three accomplices reported, 80 per cent showed conformity effects, whereas only 10 per cent shifted their responses after one other accomplice reported. They varied the number of naive subjects present relative to one instructed subject. The confederate was more effective in two- and five-person groups than in three- and four-person groups. Hare (55) investigated the influence of group size on the attainment of consensus, and found that participants in groups of five changed their opinions more toward the group consensus after discussion than those in groups of twelve. No accomplices participated; discussion time was constant, -234- thus giving each member less opportunity to exert influence on others in the larger groups. Three investigators reported no differences in shifting as a function of the number of others participating. Sherif (121) reported no significant differences in the degree of convergence for subjects responding to the autokinetic task in the presence of one or of two other members. Degree of unanimity was not prearranged; the study thus is not comparable to those employing controlled responses by others. Goldberg (49) varied the number of subjects working together in judging the intelligence of persons in nine photographs. Judging in the presence of others produced responses differing significantly from those given under private conditions. No differences in shifting were found for subjects who judged initially in the presence of two or of four other persons. Kidd (76) varied group size from one to two to four to six, and supplied fictitious, imputed norms for each group. Asch (1), in one condition, arranged for the instructed "naive" subject to respond correctly and the instructed majority of six other persons to respond incorrectly. When the person who had been giving the correct report began to agree with the incorrect majority, the frequency of shifting was found to be comparable to that under the condition of routine unanimity. Little shifting from correct reports occurred when, of four other persons reporting prior to the critical subject, two gave correct and two incorrect responses. A significant increase in shifting occurred when all four uniformly gave an incorrect answer. He suggests that the differences between his results and those reported by others may be attributable to the distinctive features of the tasks employed. The effect of the perceived discrepancy on shifting a critical subject away from his -235- private position, and the extent to which the subject shifts toward full agreement with reports by others have been evaluated. Jenness (70) used initial individual judgments of the number of beans in a jar to assign students with initially divergent estimates and those with initially similar estimates to groups of three members and four members respectively. After discussion to arrive at a group estimate, the variation among individual judgments was reduced more in the three-member than in the four-member groups. Festinger, Gerard, Hymovitch, Kelley, and Raven (40), using a labor dispute problem, prior to and during interaction measured the opinions of undergraduate students of the same sex in groups varying from six to nine members; the interaction was controlled by fictitious notes distributed after ten minutes of apparent interchange. Those who perceived themselves as initially disagreeing changed more than those who perceived themselves as initially agreeing with others present. Goldberg (49) has reported significant differences in conformity related to degree of discrepancy, but not for ratio of actual conformity to discrepancy (see foregoing). Wiener (132) reports a relationship between amount of discrepancy from norms and susceptibility, whereas Helson, Blake, and Mouton (61) confirm a positive relationship between the magnitude of discrepancy and the amount of susceptibility (see previous discussion). Greater shifts occurred for the two conditions using the smallest discrepancies between responses. The author suggests that larger discrepancies have a negative effect on the subject by tending to influence him in an opposite direction. Harvey and Rutherford (58) found that "unsuccessful," naive college subjects with one-half as many pretrials on the autokinetic task were more ready than the same size, "successful" group to shift -236- in response to consistently and uniformly divergent pressures than to initially agreeing and increasingly divergent pressures. Evidence for the greater impact of small discrepancies on judging easily discriminated materials has been presented by Blake, Helson, and Mouton (18) and by Asch (3) (see above). Since results obtained by Olmstead and Blake (107) and by Mouton, Blake, and Olmstead (103) (see the preceding) are not in complete agreement with those just summarized, further clarification is required. Wiener, Carpenter, and Carpenter (131) report failure to confirm the work of Asch (3), but do not explain their failure. In four studies of the composition of the social situation and its relation to conformity, size of the group has been demonstrated to be a critical factor, with progressive increases in shifting for increases from one to two to three persons, and little or no evidence of greater influence by a larger number. All studies agree in finding no further increments in conformity associated with increases in number of divergent reports. Currently available evidence suggests that increments beyond those attributable to three other persons may be associated with a decrement in amount of influence exerted toward conformity. Findings clearly indicate that conformity influences are significantly decreased when other members are not in unanimous agreement. With objective, discriminable stimuli, subjects tend more to agree when the discrepancy is small. For socially anchored materials, more subjects shift when the discrepancies are large. Duncker (38) found that the presence of another child, but not an adult, significantly shifted food preferences above a control condition, and younger children were more influenced by older children than the reverse. In a study by Berenda (11), the teacher serving as the accomplice influenced younger children (seven to ten) more than older children -237- (ten to thirteen), and other children as accomplices significantly influenced both age groups, with younger children more influenced. Postsession interviews demonstrated that giving a correct answer contradicted by eight peers was seen as a violation of the group for which "majority" correctness was assumed. Jacubczak and Walters (69) report contradictory results for the autokinetic effect. In their experiment, the order of exposure to adult and child peer proved highly important. The availability of an abstract only makes it impossible to evaluate completely the findings. Luchins and Luchins (89) report that greater influence was exerted when the prior report on a discrimination task was given by women than by men college student confederates. Statistical significance for differences was not reported; the number of experimental subjects was small. A number of investigations have tested the hypothesis that the higher the status of the other person, the greater his influence. Lefkowitz, Blake, and Mouton (83) introduced four variations in a traffic situation for two-thirds of the trials, one for each sixth, including a confederate dressed in high status attire who (a) obeyed or (b) violated the traffic signal; and a confederate dressed in low status attire who (a) obeyed or (b) violated the signal. Significantly greater frequency of violation occurred under the influence of a violator. An additional significant increase in the frequency of violations was found when the confederate appeared in high status attire. Mausner (96) arranged for the confederate to give the wrong answer in all trials on the Maier Art Judgment Test. The mean increase in wrong answers was significantly higher when the confederate was introduced as an art director than as a fellow student.

Unreadiness to yield under other conditions constitutes an index of resistance (13 buy 120mg sildalis fast delivery, 32 generic 120mg sildalis overnight delivery, 33 purchase sildalis amex, 109) generic sildalis 120mg line. Summary A variety of experimental situations have been employed in the study of conformity, resistance, and conversion. These have been reviewed, together with various ways of measuring the impact of the social context on the critical subject, including those which constitute indices of conformity or conversion. Stimulus materials with certain characteristics have been employed most frequently. Relative simplicity and case of measurement of -226- elicited responses is one factor accounting for the choice of materials. They rarely have involved the type of activities that are subjected to conformity or conversion pressures in our daily lives. The situations often have a quality of artificiality that makes it difficult to draw general conclusions for use in interpreting reactions in more vital and real lifelike situations. The types of influences exerted have not been of an extreme emergency, or life and death character. To approximate more closely the life conditions of conformity, it will be necessary to design experimental situations in which the maintenance of resistance to conformity pressures places an individual in jeopardy of relinquishing valued status, prestige or membership, or where conversion is a means to attain important utilitarian objectives. Personality tests have been the most popular means of assessing the role personal characteristics play in conformity behavior. Most tests have been used in only one or two studies, with the result that relatively little direct comparison of findings is possible. Among six types of conformity indices, the change of scores between pregroup and postgroup conditions has been the most widely used measure. The deviation from correct or modal responses also has been a frequently used index of change. Factors Associated with Conformity Behavior A variety of factors have been shown to arouse conformity and resistance behavior. This Ieview of findings includes sections on results of differences in the shifting of responses attributable to: (a) the nature of the stimulus materials employed to evoke conformity; (b) characteristics of the social situation; and (c) the contribution of personal factors in determining the adjustment made under conformity- producing conditions. Also included is a summary of studies of interaction effects among factors that increase or decrease conformity behavior. Differences in Shifting of Responses Attributable to Stimulus Materials Employed Several studies have evaluated those differences in conformity behavior that are associated with the nature of the stimulus materials -227- and the conditions of their presentation. Helson, Blake, and Mouton (61) studied the frequency of shifting as a function of the content of the task. Greater shifting of responses from the correct or modal report toward the erroneous responses expressed by others was observed for attitude statements than for materials involving knowledge or ability. Festinger and Thibaut (41) employed two different discussion problems as stimulus materials, and reported results consistent with those by Helson, Blake, and Mouton (61). Crutchfield (34) presented a variety of stimulus materials to a test sample under social pressure conditions. Since he describes results obtained for some but not all the materials, it is impossible to determine if response shifts are a function of the character of the stimulus materials. The materials most subject to conformity effects appear to derive meaning or validity from a social frame of reference, such as attitudes toward war or general social problems. One source of variation is the difficulty experienced by the subject in reacting to the materials presented. The hypothesis tested holds that the more difficult the materials, the more easily the individual is influenced. Blake, Helson, and Mouton (18) had male college students respond to arithmetic items and the metronome click counting problems under simulated conditions. For the arithmetic items, shifting increased toward the erroneous response of the simulated group as the difficulty of the problems increased. Results for the metronome are interpreted as indicating that variations in rate were not sufficiently great -228- for shifts from social pressure related to difficulty to appear in a statistically clear manner. Coleman, Blake, and Mouton (31) have demonstrated a significant relatiorkship between task difficulty and susceptibility to conformity pressures. The results are interpreted as indicating that an individual certain of the correct answer is more able to resist pressures because he is more able to respond in terms of internal cues. Differences between the variable lines and the standard were small for one set of trials, and larger for another set. Fewer errors Nere made by subjects when the discrepancy between lines was greater. These results support the hypothesis that difficult stimulus milterials lead to a greater degree of conformity. Bereada (11) used child subjects for two different tasks, and investigated frequency of shifting as a function of the difficulty of items. The gretatest shifting for both tasks occurred in those trials that produced the highest frequency of errors under private conditions. In a study by Wiener (132), the task consisted of selecting one of two naules for each of ten ambiguous designs, and indicating the degree of certainty of each judgment on a four-point scale ranging from "absolutely certain" to "absolutely uncertain. Pressures have been maintained at a constant level in some studies of the relationship between ambiguity of the materials and conformity. Caylor (26) defined the ambiguity of the stimulus materials as the number of equally probable reactions perceived as appropriate in response to the Stouffer questionnaire approach to conflict in norms. Conformity was found to be positively associated with the more ambiguous stimulus materials. Wiener, Carpenter, and Carpenter (131) failed to confirm the relationship reported by Caylor (26). The general hypothesis tested is that susceptibility is greater the farther removed stimulus materials are from direct examination. The materials for one were present for visual examination at the time the subject made his judgments. Significantly less influence was exerted by other persons when stimulus materials were present. Raven and Rietsema (110) studied conditions of presentation and susceptibility as a function of the clarity of the task and found that the subjects who understood the requirements conformed more to the needs of others even though this placed them at a personal disadvantage. Luchins (87) investigated susceptibility under conditions permitting some subjects to test objectively their experience with the stimulus materials. Child subjects permitted to test the accuracy of their judgments were less influenced by the confederate. These studies generally agree in confirming the prediction that susceptibility is less when subjects have the opportunity to employ an objective frame of reference. Shifting in the direction of endorsement of a petition as a function of the strength of the request has been investigated by Blake, Mouton, and Hain (19). An increase in compliance attributable to increases in strength of the request was found for influence created by the compliant model, and a decrease when the model resisted. These results were confirmed by Rosenbaum (112) using a similar request to solicit volunteers. The frequency of compliance was found to be positively or negatively related to the strength of the prohibition stimulus in the same manner as in the studies just summarized. Reactions are evoked more easily when pressures are exerted on attitudes toward social issues; factual matters and personal preferences seem to be most resistan to change. This generalization is important for its implication that susceptibility is highest in areas dealing with political ideology, social attitudes, and expressions of opinions. A situation where it is difficult for the subject to check on the accuracy of his response results in a decrease of resistance. Greater susceptibility has been shown to occur with increases in request strength when pressures are created by a compliant model as well as the converse. Conformity Behavior and Social Context Conformity pressures may be created when a person is confronted with reactions differing from his own. Individual reactions under private conditions have been compared with reactions to the same problem in a social context. Properties of social contexts singly or in combination have been studied to determine their effects on increases or decreases in susceptibility. Knowledge of group opinion during the third administration of an attitude questionnaire -231- produced frequency of shifting in the direction of agreement with the majority three times greater than that in the control condition, with disagreement reduced to approximately one-half of chance expectancy.

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Products based on hyaluronates are widely used in intraocular surgery as a substitute for vitreous humor and as an adjuvant to promote tissue repair sildalis 120 mg low price. Hyaluronates show a topical protective effect for the corneal endothelium and other delicate tissues from mechanical damage through providing a stabilized hydrogel discount sildalis 120 mg otc. Sodium hyaluronate with its unusual rheological quality buy cheap sildalis 120mg on-line, producing a rapid transformation from a liquid to a solid character with increasing stress frequency purchase sildalis 120mg mastercard, appears to be beneficial for topical vehicles. The pseudoplastic behavior of hyaluronate solutions, where viscosity is higher at the resting phase, provides a thickened tear film, slow drainage and an improved distribution on the cornea during blinking. Furthermore, the carboxyl groups of hyaluronate form hydrogen bonds with sugar hydroxyl groups of mucin when sodium hyaluronate is applied in the eye, producing an intimate contact with the cornea. These unique properties give hyaluronates great potential in ocular drug delivery. Chondroitin sulphate is another polysaccharide derivative (glycosaminoglycan) with a repeat unit containing β-D-glucoronic acid and D-N-acetyl galactosamine, very similar to hyaluronic acid except for modification of the position of a hydroxyl group and the addition of sulphate groups to the galactosamine residue. Chondroitin sulphate has a good affinity to the corneal surface, preventing premature breakup of the tear film between blinks. Formulations containing chondroitin have been used for the treatment of dry eye and showed superiority to hyaluronic acid in treating severe cases of keratoconjunctivitis sicca. Synthetic polymers Carbomers are poly (acrylic acid) polymers widely used in the pharmaceutical and cosmetic industries. They have several advantages, including high viscosities at low concentrations, strong adhesion to mucosa without irritation, thickening properties, compatibility with many active ingredients, good patient acceptability and low toxicity profiles. These properties have made carbomers very valuable in the field of ophthalmic formulations. Artificial tear products and novel drug delivery systems based on carbomers have been extensively formulated. A recent scintigraphic study on Geltears (a Carbopol 940 based product) showed that the precorneal residence is significantly prolonged by carbomer gel when compared to the saline control. Phase transition systems The introduction in the early 1980s of the concept of in situ gel systems demonstrated that a considerable prolongation in duration of action could be obtained. In situ gelling systems have unique properties, which can make a liquid change phase to a gel or solid phase in the culde-sac upon its instillation into the eye. Three methods have been employed to induce phase transition on the eye surface: change in pH and temperature as well as activation by ions. Cellulose acetate phthalate forms a pH-triggered phase transition system, which shows a very low viscosity up to pH 5. The half-life of residence on the rabbit corneal surface was approximately 400 seconds compared to 40 seconds for saline. However, such systems are characterized by a high polymer concentration, and the low pH of the instilled solution may cause discomfort to the patient. When the solution is instilled onto the eye surface (34 °C) the elevated temperature causes the solution to become a gel, thereby prolonging its contact with the ocular surface. One of the disadvantages of such a system is that it is characterized by a high polymer concentration (25% poloxamer), and the surfactant properties of poloxamer may be detrimental to ocular tolerability. Gellan gum is an anionic polysaccharide formulated in aqueous solution, which forms clear gels under the influence of an increase in ionic strength. The gellation increases proportionally to the amount of either monovalent or divalent cations. The reflex tearing, which often leads to a dilution of ophthalmic solutions, further enhances the viscosity of the gellan gum by increasing the tear volume and thus the increased cation concentration. It is also possible to develop systems which undergo both temperature and pH dependent changes in structure. Carbomers form acidic, low viscosity, aqueous dispersions that transform into stiff gels when the pH is raised. Although these aqueous materials can form gels in situ in the conjunctival sac upon instillation, they often cause irritation to the eye due to their high acidity and sometimes the dispersions are not easily neutralized by the buffering action of the tear fluid. Various polymer combinations have been investigated in attempts to improve the gelling properties and reduce the total polymer content of formulations, thereby improving their tolerability. Dispersed systems These can be grouped into suspensions, particulates, liposomes and emulsions. Suspensions 311 Suspensions are commonly formulated by dispersing micronized drug powder (< 10 μm in diameter) in a suitable aqueous vehicle. Ophthalmic suspensions, particularly for the steroids, are thought to be acceptable as delivery systems since it is assumed that drug particles persist in the conjunctival sac giving rise to a sustained release effect. However, suspensions have a disadvantage that the concentration of dissolved drugs cannot be manipulated due to their relative insolubility in the vehicle. Several investigators have shown the importance of particle size of the suspension in ocular drug delivery. Unfortunately, a particle size above 10 μm in diameter may result in a foreign body sensation in the eye following ocular application causing reflex tearing. A reduction in particle size generally improves the patient comfort and acceptability of suspension formulations. Particulates Although the suspension technique may be useful in extending drug release under certain conditions, it is only applicable to drugs that are practically insoluble in water, such as corticosteroids. For drugs that are somewhat water-soluble, the particulate approach may be considered. Particulates are commonly classified into micro- and nanoparticles based on the size of the particles. Nanoparticles are colloidal particles ranging from 10 to 1,000 nm, in which drug may be entrapped, encapsulated, and/or absorbed. Microparticulates are drug-containing small polymeric particles (erodible, non-erodible or ion-exchange resins) within the size of 1–10 μm, which are suspended in a liquid carrier medium. Several distinct approaches have been used to formulate drugs in a microparticulate dosage form suitable for topical application. These include erodible microparticulates, swelling mucoadhesive particulates, pH responsive microparticulates, latex systems, ion-exchange resins, etc. Upon administration of particle suspension to the eye, the particles reside at the delivery site (cul-de-sac, sub conjunctiva or vitreous humor) and the drug is released from the particles through diffusion, chemical reaction, polymer degradation, or ion-exchange mechanism, resulting in increased ocular absorption. Piloplex was one of the first commercial exploration of nanoparticle formulations in ocular drug delivery. The formulation consists of pilocarpine-loaded nanospheres of poly(methylmethacrylate-acrylic acid) copolymer. Following this introduction, many nanoparticle systems have been investigated for the prolongation of contact time in order to increase the ocular absorption. A significant reduction in intra- ocular pressure was noted following administration of betaxolol-poly- ε caprolactone nanoparticles, compared to the commercial eyedrops. The enhancement was ascribed to two factors: one because the nanoparticles increased the precorneal retention of the drug by agglomeration; and secondly because the entrapped drug was in the non-ionized form in the oily core of the carrier and could diffuse at a great rate into the cornea. Similar improvements were obtained with carteolol (β-blocker) which induced a better penetration of the drug from the nanosphere formulation. Liposomes Liposomes can be defined as microscopic vesicles, composed of membrane-like lipid bilayers surrounding aqueous compartments (see Section 5. Phospholipids commonly used in the preparation of liposomes are phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidic acid, sphingomyelin, cardiolipins and cerebrosides. The versatility in manufacturing and use of liposomes is attributed to their amphiphilic nature. Both hydrophilic and lipophilic drugs can be encapsulated within the lipid vesicles. It has been shown that drugs with very low or very high logP values exhibit prolonged liposomal retention. The first application of liposomes in ocular drug delivery involved the application of a 312 liposomal suspension of idoxuridine to rabbits for the treatment of herpes simplex keratitis. The liposmal formulation was found to be more efficient results compared to the aqueous solution. Liposomes can be easily prepared from non-toxic materials, which are non-irritant and do not obscure vision. Unfortunately, routine use of liposomes in topical ocular drug delivery is presently limited by short shelf life of the formulation, limited drug loading capacity and obstacles in sterilizing the preparation. Emulsions Emulsions have been used for centuries for the oral administration of medical oils and vitamins and as dermatological vehicles.

Melatonin delivery in solid lipid nanoparticles: Prevention of cyclosporin A induced cardiac damage purchase 120 mg sildalis overnight delivery. Baclofen-loaded solid lipid nanoparticles: H-reflex modulation study purchase generic sildalis line, behavioural characterization and tissue distribution in rat after intraperitoneal administration safe sildalis 120 mg. In vitro and in vivo study of solid lipid nanoparticles loaded with superparamagnetic iron oxide purchase sildalis discount. Intracellular accumulation and cytotoxicity of dox- orubicin with different pharmaceutical formulations in human cancer cells. Solid lipid nanoparticles in lymph and plasma after duodenal administration to rats. Biodistribution of stealth and non-stealth solid lipid nanoparticles after intravenous administration to rats. Intravenous administration to rabbits of non-stealth and stealth doxorubicin loaded solid lipid nanoparticles at increasing concentration of stealth agent: Pharmacokinetics and distribution of doxorubicin in brain and in other tissues. Transport in lymph and blood of solid lipid nanoparticles after oral administration in rats. Presented at the Proceedings of the 24th International Symposium on Controlled Release of Bioactive Materials, Stockholm; 1997:179–180. Preparation and evaluation in vitro of colloidal lipo- spheres containing pilocarpine as ion-pair. Evaluation in vitro/in vivo of colloidal lipospheres containing pilocarpine as ion-pair. Highly efficient cellular uptake of c-myb antisense oligonucleotides through specifically designed polymeric nanospheres. Nanoparticle formulation enhances the delivery and activity of a vascular endothelial growth factor antisense oligonucleotide in human retinal pigment epithelial cells. Idarubicin solid lipid nanospheres administration to rats by duodenal route: Pharmacokinetics and tissues distribution. Pharmacokinetics of melatonin in man after intravenous infusion and bolus injection. Solid lipid nanoparticles incorporating melatonin as new model for sustained oral and transdermal delivery systems. Microemulsions – Modern colloidal carrier for dermal and transdermal drug delivery. Effects of phospholipids based formulations on in vitro and in vivo percutaneous absorption of methyl nicotinate. Comparison of stratum corneum penetration and localization of a lipophilic model drug applied in an o/w microemulsion and an amphiphilic cream. Bicontinuous sucrose ester microemulsion: A new vehicle for topical delivery of niflumic acid. Transdermal permeation of apomorphine through hairless mouse skin from microemulsions. Transdermal apomorphine permeation from microemulsions: A new treatment in Parkinson’s disease. Nocturnal anomalous movement reduction and sleep microstructure analysis in parkinsonian patients during 1-night transdermal apo- morphine treatment. Although nanoparticles are per- haps the simplest of nanostructures, nanoparticle-based technologies are broadly covering different fields, ranging from environmental remediation, energy genera- tion, and storage all the way to applications in bioscience (1–5). The need to fine-tune different nanoparticle properties to make them suitable for specific applications has sparked a large number of worldwide research efforts aimed at their tailoring. However, full use of these structures in these applications requires more detailed information and a feedback of data coming from reliable characterization techniques (6–8). Several methods have been applied to obtain this information and some of them are described in different chapters of this book. In this contribution, an overview of the recent progress in nanoparticle charac- terization is presented. Some of the aforementioned methods will be introduced and the kind of information that can be obtained from them will be discussed. However, a detailed account of a specific characterization method and its variations is outside the scope of this review. Therefore, if imaging at consider- ably higher resolution is required, electromagnetic radiation of shorter wavelengths must be used. The development of electron microscopes has resulted in instruments that are able to routinely achieve magnifi- cations of the order of 1 million and that can disclose details with a resolution of up to about 0. When an electron beam interacts with a sample, many measurable signals are generated and electrons can be transmitted, backscattered, and diffracted. Depend- ing on the sample thickness, transmitted electrons pass through it without suffer- ing significant energy loss. Since the attenuation of the electrons depends mostly on the density and thickness of the sample, the transmitted electrons form a two- dimensional projection of the sample. Elec- trons can also get diffracted by particles if these are favorably oriented toward the electron beam; the crystallographic information that can be obtained from these diffracted electrons is the basis for electron diffraction. Finally, the electrons in the primary beam can collide with atoms in the sample and be scattered back, or, in turn, remove more electrons from these atoms (secondary electrons). These two pro- cesses (backscattering and generation of secondary electrons) are more effective as the atomic number of the atom increases. More recently, changes in nanoparticle structure as a result of interactions with gas-, liquid-, or solid-phase substrates can now be monitored by this technique (11). In recent years, a large number of new and novel developments have been made in electron microscopy for nanotechnology. This includes new techniques such as in situ microscopy used for imaging dynamic processes, quantitative chem- ical mapping, holographic imaging of electric and magnetic fields, and ultrahigh- resolution imaging (12). For instance, the study of nanoparticles can be greatly improved with the use of aberration-corrected lenses, enabling image resolutions at levels sometimes lower than 1 A˚ (13,14). This level of image resolution yields a new level of understanding of the behavior of matter at the nanoscale. Beam sus- ceptibility makes it very difficult sometimes to carry out electron diffraction studies on nanoparticles that are prone to beam damage. In this case, by using low electron beam currents, it is possible to obtain lattice fringe images and electron diffraction. Figure 1 shows an example of a study using an aberration-corrected elec- tron microscope to study the structure and morphology of AuPd bimetallic par- ticles (16). The authors matched the experimental intensities of atomic columns with theoretical models of three-layered AuPd nanoparticles in different orienta- tions. Based on this information, the authors indicated that the surface layer of the metallic nanoparticles contains kinks, terraces, and steps at the nanoscale. The inset indicates the authors’ proposed sketch of element-rich locations in the layers. The inten- sity profile through a typical AuPd nanoparticle is displayed in Figure 1(B), and it depends on the atomic number and the column thickness. The contrast is due to a core–shell structure consisting of three layers as sketched in the inset. When this occurs, the surrounding matrix usually tends to mask the supported nanopar- ticles. In some special cases, however, the existence of an epitaxial relationship between the nanoparticles and their support can be used to obtain size and shape information (17). Moreover, nanoparticles can be susceptible to damage under the electron beam irradiation conditions normally used for high-resolution imaging. Problems become even more exacerbated when the nanoparticles under study have tendency to adhere strongly to each other, forming agglomerates. Consequently, bulk-sensitive methods that provide information regard- ing the quality, size, and structural properties of a given sample must be employed. Among these methods, Raman spectroscopy and optical absorption deliver the most comprehensive results. This technique is based on the well-known phenomenon of light absorption by a sample. In particular, the infor- mation obtained on the band energy gap is extremely useful to evaluate the dis- persion and local structure of nanoparticles formed by d0 transition metal oxides, sulfides, and selenides (22–26). Several methods have been proposed to estimate the band energy gap of these materials by using optical absorption spectroscopy. A general power law form has been suggested by Davis and Mott (27), which relates the absorption coefficient with the photon energy.

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