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Introduction of the wild-type p53 gene in a colon cancer xenograft model has been shown to induce tumor regression due to apoptosis order generic viagra soft online. Lung cancer cells are frequently deficient in p53 and are susceptible to the induction of apoptosis by overexpressed p53 50 mg viagra soft otc, making this tumor particularly suitable for gene therapy by p53 order 100 mg viagra soft fast delivery. Systemic administration of the tumor suppressor gene p53 complexed with cationic liposomes significantly reduced tumor growth and metastases of nude mice injected with cancer cells purchase generic viagra soft canada. The pulmonary endothelium may act as a bioreactor for the production and secretion of therapeutic proteins, such as clotting factors and erythropoietin into the blood circulation. There is a potential benefit for acquired lung diseases, as well as cancers, to be controlled and possibly treated by expression of cytokines, surfactant, antioxidant enzymes, or mucoproteins within lung cells. Plasmid can be delivered to the lung by intravenous injection, intratracheal by instillation or inhalation. Gene delivery to the submucosal glands of the upper airway is of particular interest, though challenging for treatment of cystic fibrosis, where correction of the genetic defects in the glands may improve the alterations in the patients’ secretions. Aerosolization requires monodisperse particles, since the deposition of inhaled particles in the airway depends on particle size (see Section 10. As has been detailed in Chapter 10, larger particles (>5 μm mass median diameter) tend to deposit mainly in the larynx and upper airways. With droplets < 5 μm , there is an increase in airway and alveoli deposition, but alveolar deposition is far greater. The inhaled dose is dependent on the minute volume and entrainment efficiency of the subject and therefore has considerable intersubject variability. Such variability will only be accentuated in many diseases in which the airways are obstructed by mucus. Still, aerosolization of plasmid/lipid complexes has been successfully used for gene delivery into the airways of mice and rabbits with a pump spray device and is under clinical trials for gene delivery to the nasal epithelium. Intratracheal instillation bypasses the barrier of the endothelial cell layer that is associated with systemic gene delivery. Almost 80–90% of the starting material is wasted in aerosol gene delivery irrespective of the inhalation device employed. Therefore, intratracheal instillation of plasmid/lipid complexes is being investigated as an alternative to deliver transgenes to the lung. Plasmid/lipid complexes, not plasmid alone, are effective in aerosolization, whereas plasmids alone can efficiently be transfected to rat and mouse airway epithelial tissues when given by the intratracheal route. Altering the physicochemical characteristics of the formulated plasmids can vary the distribution of plasmid to the bronchial tree. Immunohistochemical studies of lung tissues after intratracheal administration of plasmid/lipid complexes have shown gene expression mainly within the epithelial cell layer lining the bronchus. Depending on the site of expression and the nature of antigen, in vivo expression of plasmids encoding antigen can provide superior cellular, humoral and mucosal immunity. The efficacy of genetic vaccines could be enhanced or modulated through the use of formulations that increase nucleic acid stability or distribution in the tissue, the coexpression of immune molecules that affect the processing of antigens, or through the use of adjuvants that affect the immune response. Genetic vaccines have been applied to several systems, including immune responses against cancer antigens, mycoplasma, tuberculosis, malaria, parasites, and viral infections. Two types of immunity may be induced in response to an antigen, namely humoral immunity mediated by antigen-specific antibodies produced by B lymphocytes, and cell-mediated immunity produced by activated macrophages and cytotoxic T lymphocytes. Antibodies may neutralize pathogens, whereas 355 cytotoxic T lymphocytes can destroy infected cells or control infection by noncytolytic means. Antibody- mediated immunity effectively prevents infection by binding to the infectious organisms and then eliminating either directly or via phagocytic ingestion by neutrophils and/or monocytes. Antibodies also bind to the surface of infected cells expressing the specific antigen. Several routes, including intramuscular, subcutaneous, intravenous, intradermal, nasal, and oral administration, have been investigated for the administration of genetic vaccines. Of these routes, intramuscular injection of genetic vaccines generated the best response. Mature myotube has been shown to be the target for the uptake of plasmid after intramuscular administration. Plasmid can enter the bloodstream and lymphatic system after intramuscular administration and traffic to the spleen, liver, kidney, lymph nodes and bone marrow. It is not clear whether the production of antigens in muscle has unique properties with respect to the elicitation of a prolonged immune response or whether expression in any tissue in the periphery is sufficient for the induction of an antigen-specific immune response. Single injection provides for a full humoral and T cell response for 60–70 weeks, with the antibody titer being higher than that achieved by intramuscular injection. Skin is rich in dendritic cells, which are potent initiators of immune responses and possess the co- stimulatory and adhesion molecules required for T cell activation. Thus, transfection of plasmids into these cells is likely to elicit both cellular and humoral responses. Specific targeting of dendritic cells residing in the lymph nodes will likely represent an attractive strategy for providing a robust immune response with nucleic acid vaccines. Plasmid-based (or non-viral) gene therapy has generated considerable research interest because of many inherent advantages over the viral vectors in terms of safety, immunogenicity and ease of manufacture. Gene therapy offers unique opportunities in the development of novel products that produce intracellular proteins. Several plasmid-based approaches are already in clinical trials and offer the potential of safe and effective gene therapy. To enhance the therapeutic efficacy of 356 proteins using plasmid-based expression systems, many fundamental questions related to their pharmaceutical formulation, biodistribution and intracellular trafficking still need to be addressed. Describe the pharmacodynamic and pharmacokinetic barriers to effective plasmid-based gene delivery. Outline the various approaches to cancer gene therapy presently being investigated. Traditionally new chemical entities have been identified by the screening of natural products and chemical libraries to identify potential lead compounds. These lead compounds have then been optimized through an iterative lead-optimization process involving the synthesis of analogs, the development of quantitative-structure-activity relationships and the use of molecular modeling to obtain new chemical entities with high specificity and affinity for the therapeutic target for pharmaceutical development. The development of combinatorial chemistry has led to the ability to produce vast libraries of compounds for initial screening. The evaluation of combinatorial libraries using high-throughput screening technologies allows the rapid screening of potential lead compounds with a wider molecular diversity against a broad range of therapeutic targets. Until recently, therapeutic targets were identified through the application of basic pharmacology and biochemistry with both receptor and enzyme targets being identified and isolated from specific tissues. The identification of potential therapeutic targets has been further enhanced through the recent development of genomics and proteomics. These techniques provide mechanisms to identify upregulated gene and protein expression in diseased tissue providing pointers towards potential means of therapeutic intervention. The advances in molecular biology have also led to the ability to clone receptors into various cell types to facilitate screening of potential ligands against such targets. The parallel development of cell biology has led to the ability to utilize cell-based assays rather than tissue-based assays for drug screening and the advances in robotics have led to the development of high-throughput screening technologies. The development of genomics, proteomics, high-throughput screening and combinatorial chemistry has led to an information explosion within pharmaceutical companies requiring better mechanisms for the storage and manipulation of biological and chemical data. This has driven the development of the field of bioinformatics which serves to provide searchable databases allowing comparison of molecular and biological information to potentially identify other therapeutic targets and lead compounds. This chapter aims to provide a brief overview of these different technologies to provide a basis for the reader to develop their understanding of this field in order to appreciate how these technologies will underpin the future of drug delivery and targeting. The majority of combinatorial approaches utilize polymeric solid supports as a base onto which the compounds are synthesized. However, there are also approaches which utilize solution- based chemistries to generate combinatorial libraries. Such supports are traditionally composed of polymeric resin beads on to which the synthesis of a peptide is undertaken in a stepwise fashion with each amino acid being added sequentially to the peptide chain (Figure 15. After coupling the amino acid to the peptide chain, the protecting group is removed from the terminal amino acid exposing a reactive site to which another amino acid may subsequently be coupled. This technique relies on the clean coupling of amino acids in peptide synthesis, the ability to easily remove reactants and solvents and wash the products between each stage of the synthesis and the ability to protect and deprotect reactive groups on the solid support as necessary. An example of a 3×3×3 combinatorial split and mix combinatorial synthesis is shown in Figure 15. The technique involves three initial batches of resin beads to which are initially coupled, for example, a different amino acid. These batches are then combined, mixed and split again into three batches; each batch now containing a mixture of beads containing different amino acids. A different amino acid is then coupled to each of these batches of beads, the beads mixed, split and the process repeated a third time.

Radiographic metabolite buy viagra soft no prescription, chlorothiazide viagra soft 100mg with visa, were detected in the analysis of urine extracts (n = 110) collected from urine by liquid chromatography-mass spectrom- fve healthy subjects and three patients given etry 120 hours afer administration (Deventer [14C]hydrochlorothiazide orally revealed a single et al purchase viagra soft cheap. However discount viagra soft 50 mg on line, two samples from one subject collected on the second and third (i) Pregnancy days afer dosing revealed some radiolabelled A study of 10 pregnant women given a daily material (< 0. Te nature of this sion) demonstrated that the diuretic crossed the material was found by Okuda et al. Hydrochlorothiazide substantial reduction in the extent and rate of was not however detectable (detection limit, absorption of hydrochlorothiazide (recovery of 20 ng/mL) in the blood of the nursing infant only 21–37% of the administered dose in three (Miller et al. Since the reduced in the extent and rate of elimination of hydro- intestinal mobility shown in cardiac failure chlorothiazide; only about 10% of an oral dose would be expected to promote the uptake of was recovered, and the elimination half-life hydrochlorothiazide, the observed decrease in was increased from a mean value of 6. Tese patients absorption was considered not to be reduced in were older than those studied previously (age, these patients, since the area-under-the-curve 40–60 years), and it was considered that reduced values were greater in those with low creatinine renal function and age may have been factors clearance than in healthy subjects. In patients in the reduction of absorption (Beermann & with severe renal impairment, the elimination Groschinsky-Grind, 1979). Analyses of serial fve patients who received an oral dose of hydro- samples of blood and urine collected over 36 chlorothiazide of 775 mg (at times ranging from hours demonstrated that the pharmacokinetics 1. No signifcant pharmacokinetic interactions (a) Mutagenicity have been noted between hydrochlorothiazide Te Working Group did not identify any new and propranolol, metoprolol, sotalol, or acebut- data on the mutagenicity of hydrochlorothiazide olol. In two studies, hydro- spironolactone and indomethacin, allopurinol chlorothiazide was not mutagenic to Salmonella and its metabolite, oxipurino1, and phenytoin typhimurium in the presence or absence of an (Welling, 1986). Hydrochlorothiazide was triamterene as components of a fxed drug not mutagenic in bacterial screening systems, combination revealed diferences in bioavaila- with or without enzymatic activation, but can bility from combination tablets and capsules, but form chemically reactive mutagenic products subsequent work suggested that these diferences afer reaction with nitrite, a product of nitric may have been due to the efects of formulation oxide (Andrews et al. Tis was proposed to be because hydro- an arg– strain of Escherichia coli (Hs30R) (Fujita, chlorothiazide does not undergo metabolism in 1985). Clinical evidence also indicates that hydro- (b) Chromosomal damage chlorothiazide can act as a photosensitizer in Chromosomal damage caused by hydro- the presence of irradiation by ultraviolet A or chlorothiazide was reviewed by a previous ultraviolet B (Addo et al. In a phototoxic exanthem is “occasional” (> 1/1000 to spot test, hydrochlorothiazide did not induce < 1/100) (Rote Liste Service GmbH, 2012) nondisjunction and mitotic crossing-over in Aspergillus nidulans (Bignami et al. Chromosomal aberrations were not found in Chinese hamster lung cells, but polyploidy 5. Summary of Data Reported was observed afer treatment with hydrochloro- thiazide for 48 hours (Ishidate et al. Hydrochlorothiazide is a thiazide-based Hydrochlorothiazide was found to induce diuretic that is recommended as a frst-line micronucleus formation and chromosome therapy for hypertension. Most frequently, breakage in cultured human lymphocytes via hydrochlorothiazide is used with other drugs that chromosome delay (Andrianopoulos et al. Efect modifcation by sun exposure is potentially important, but had not been thor- 5. Te case–control lacked dose–response relationships, or gave study from Denmark reported an excess risk of results that were close to unity. Tis was followed by a nested case–control also found an increased risk of renal cell carci- study of cancer of the lip in the same population, noma among women with unspecifed thiazide which reported a statistically signifcant twofold use. Tis association was difcult to interpret increase in risk for three or more prescriptions, owing to potential confounding by hypertension, and increasing odds ratios with duration of use. Tis was the only study with adequate statistical Two case–control studies on cancer of the power to assess use of hydrochlorothiazide alone. Evaluation carcinoma (combined) in male mice; there were no signifcant increases in the incidence of any 6. In the second study, there was an increased incidence of adrenal Tere is limited evidence in humans for the pheochromocytoma in female rats. Positive cant increase in the incidence of any neoplasm associations were observed for squamous cell was observed in male rats in the second study, carcinoma of the skin and lip. Hydrochlorothiazide increased the frequency of sister chromatid References exchange, but not chromosomal aberration, in Chinese hamster ovary cells, both in the presence Abdel Razak O (2004). In-vitro induction of micronucleus Intrahepatic distribution of hydrochlorothiazide and formation and chromosome breakage via chro- quinidine in rats: implications in pharmacokinetics. Tiazide- In the presence of ultraviolet A irradiation, induced photosensitivity: a study of 33 subjects. Genotoxicity of hydrochlorothiazide in 314 Hydrochlorothiazide cultured human lymphocytes. Malabsorption of hydrochlorothiazide Prevention, Detection, Evaluation, and Treatment of following intestinal shunt surgery. Pharmacokinetics of hydrochlorothiazide Detection, Evaluation, and Treatment of High Blood in fasted and nonfasted subjects: a comparison Pressure. Eur J Clin Pharmacol, for skin cancer in European populations: a multicentre 13(5):385–7. Arginine reversion and lambda induction Programme on Chemical Safety, World Health in E. Trends in antihy- porter 1 protein is induced by chronic furosemide or pertensive medication use and blood pressure control hydrochlorothiazide infusion in rat kidney. Nephrol among United States adults with hypertension: the Dial Transplant, 18(8):1505–11. Diuretics for hypertension–an Hallas J, Christensen R, Andersen M, Friis S, Bjerrum L inconsistency in primary care prescribing behaviour. Br J Clin Pharmacol, Kunisada M, Masaki T, Ono R, Morinaga H, Nakano E, 74(1):180–8. Pathologic efects of Okuda T, Itoh S, Yamazaki M, Nakahama H, Fukuhara chronic administration of hydrochlorothiazide, with Y, Orita Y (1987). Kinetics of hydrochloro- ment of arterial hypertension of the European Society thiazide absorption in humans. Hydrochlorothiazide disposition in a mother and her Rapid determination of hydrochlorothiazide in breast-fed infant. Long-term diuretic therapy in patients with coronary disease: increased colon cancer-related mortality over a 5-year follow-up. Outpatient hypertension treatment, treatment intensifcation, and control in Western Europe and the United States. Liquid chromatographic-tandem mass spectrometric method for the simultaneous quantitation of telmis- artan and hydrochlorothiazide in human plasma. Name: 2,4-Tiazolidine- dione, 5-[[4-[2-(5-ethyl-2-pyridinyl)ethoxy] phenyl]methyl]- (SciFinder, 2013). Name: 2,4-Tiazolidine- exposed to both drugs, which were sometimes dione,5-[[4-[2-(5-ethyl-2-pyridinyl)ethoxy] prescribed sequentially. Te Working Group did phenyl]methyl]-, hydrochloride (1:1) not consider other thiazolidinediones, such as (SciFinder, 2013). Actos; Glustin; Glizone; Pioz; Zactose (Rx Tere are numerous methods including List, 2013). It is indicated particularly for over- weight patients as an adjunct to diet and exercise to improve glycaemic control. It is contraindi- cated in patients with type 1 diabetes mellitus, and for the treatment of diabetic ketoacidosis. Prescription trends from zone is also used for other of-label indications the Netherlands also declined afer regulatory (Table 1. No information was available to the Working Group on the potential pioglitazone number of workers exposed. Te production and medicinal use of pioglitazone pioglitazone may contaminate the environment through various waste streams (Pubchem, 2013). Name: 2,4- methanol (O’Neil, 2006) Tiazolidinedione, 5-[[4-[2-(methyl-2-pyrid- Melting point: Rosiglitazone: 151–155 °C inylamino)ethoxy]phenyl]methyl]-, (2Z)-2- (O’Neil, 2006) butenedioate (1:1) (SciFinder, 2013) 3 Density: 1. Selected non-compendial methods are (b) Rosiglitazone maleate presented in Table 1. Other analytical methods for detection in human urine include square-wave adsorptive stripping voltammetry method (Al-Ghamdi & 1. Te compound obtained • Succinate impurity or 2-(5-(4-(2-(methyl- (pyridin-2-yl)amino)ethoxy)benzyl) is dissolved in dioxane and hydrogenated at -2,4-dioxothiazolidin-3-yl)succinic acid room temperature and atmospheric pressure. Since the marketing authorization for cations such as polycystic ovarian syndrome and rosiglitazone was suspended, rosiglitazone is no insulin resistance syndrome. Side-efects include fuid retention, conges- Prescriptions for rosiglitazone have also declined tive heart failure, and liver disease (Pubchem in several other countries across Asia, such as Substance, 2013).

Oncological diseases are responsible for the failure of the body to produce a complete immune response against the tumor due to its lack of immunogenicity generic 50 mg viagra soft. Most of the currently available methods of cancer treatment (surgery discount 50mg viagra soft with mastercard, chemotherapy buy generic viagra soft 50mg online, radiation therapy) also induce cell immunosuppression 50 mg viagra soft mastercard, which contributes to recurrence of cancer. Understanding the role of oncogenes and their products in the malignant transformation of cells, the mechanisms underlying the anti-tumor immunity failure, the biological nature of drug resistance necessitates the implementation of methods that can strengthen endogenous mechanisms of antineoplastic defense. Carry out an analytical review of the most promising methods of biotherapy of oncological diseases. Immune system is the main point of biotherapy application, which is based on the activation of protective mechanisms or introduction of natural polymer molecules (cytokines, growth factors, etc. Currently, the main hope of biotherapy in cancer is associated with vaccine therapy, gene therapy, virotherapy (oncolytic viruses), the use of cytokines and monoclonal antibodies. At that the use of viruses as anticancer agents is considered to be a highly promising method. Scientists discovered a new facet of biological features of viruses, which have always been regarded as disease-causing agents, namely their vector, immunomodulating and anti-tumor functions. Researchers suggest mainly natural attenuated strains of viruses as therapeutic agents against cancer, such as viruses of influenza, Newcastle disease, herpes and various recombinant viruses, derived from natural ones by genetic engineering. Such manifestations of viral infections as cytolytic activity, induction of new or modifications of existing antigens of the tumor cells, viral immunogenesis reproduction of viruses by budding (transfer of tumor antigen), interferonogenesis, increase in the sensitivity of tumor cells to therapeutic effects and endogenous antitumor mechanisms that allow us to consider the use of virotherapy a promising approach to immunotherapeutic effect on tumor growth. It is known that one of the universal elements of tissue injure during pathological processes is oxidative stress. The use of antioxidants for the treatment of wound healing, ensures prevention of secondary necrosis and stimulate regeneration Aim. The aim of this study was to investigate the intensity of peroxidation protein in rats with burn wounds in the treatment of gel containing silver nanoparticles stabilized polyvinylpyrrolidone, that corresponding 0. Nanocomposite of silver, that experimental gel contained, obtained at the Institute of Electric them. Blood sampling for analysis performed in two periods: 7 days of treatment, when the scabs began to withdraw and for 21 days (complete healing of all animals). Results processed using program "Statistica", used for nonparametric data the criterion Mann- Whitney (p>0. In recent years it was accumulated a considerable amount of material on the relationship of various deficiency of certain micronutrient with diabetes risk – first of all it is chromium, magnesium, zinc, vitamin A and vitamin D. Today, vitamin D deficiency is associated with obesity, high body mass index, insulin resistance, adverse effects on insulin secretion and with glucose tolerance. Theoretical studying the role of vitamin D deficiency in the development of diabetes. In patients, which suffer from diabetes mellitus and metabolic syndrome, indices of insulin resistance are growing. Thus, depressed level of 25- hydroxycholecalciferol (25(ОН)D) in blood serum correlates with simultaneous presence of cardio-metabolic risk factors at diabetes mellitus. Among patients with low concentrations of 25(ОН)D in serum there is increased risk of metabolic syndrome on 70 %. Level of vitamin D in plasma influence on concentration of glycozilated hemoglobin (HbA1c) – long-term index of glucose tolerance. At the same time at higher concentrations of 25(ОН)D the decrease of HbA1c was observed. There is an opinion that formation and accumulation of final products of glycosylation affects on metabolism in bone and its solidity. Especially, diabetic neuropathy can lead to exacerbation of bone resorption process, and macro- and microangiopaties –can disturb blood inflow to bones. On pancreatic β-cells, as well as on cells of immune system special vitamin D and vitamin D-binding protein receptors are present. In studies on rats with induced diabetes the decrease of vitamin D-binding protein level on 62% comparing to healthy animals was established. Likewise, it is considered that vitamin D can contribute to maintenance and stimulation of insulin secretion. However tropism existing analeptics, varying degrees of influence on specific brain structures, a narrow range of therapeutic effects, toxicity narrows the scope of their application. The analysis of the pharmaceutical market in the last 50 years has shown that the amount of analeptic drugs has not changed and has less than a dozen, which makes creation of original domestic analeptic perepativ actual problem of modern pharmacy and medicine. The aim – focused search of the original substance with analeptic and anti anesthesial action. To optimize search of analeptic substances were used methods of descriptive and statistical computer modeling. Assessment and analeptic and anti anesthesial action promising substances was conducted on mice in accordance with accepted standards. The initial screening of original pharmacological substances for the analeptic action performed on the model of ketamin anesthesia, after which was set optimal effective dose and acute toxicity (intravenously intraperitoneally and oral) of substances leader. Study features analeptic action of the given substance scheduled in comparison with caffeine niketamid, sulfokamfokayin and other substances in various models of anesthesia (viadril, tiopental, hexenal) and the model of alcohol intoxication. Further experiments include determining the best mode of application, installation dose dependency, regimen in a single system and use the most effective substance. The research helped to choose the leader of the substance with a pronounced awakening effect. Derivatives of sulfur and nitrogen-containing heterocyclic were looking to find new analeptics. The class of peptidergic neuroprotector and nootropic drugs attracts particular attention. Previous research allowed to reveal their neuroprotectivе and nootropic properties. The study is aimed to found st nd rd the influence of neuropeptides on the 1 , 2 and 3 memory stages in mice. Amnesia has been reproduced by scopolamine intraperitoneal injection at a dose of 1. The anti-amnestic activity (AaA) of neuropeptides was calculated with the Battler formula. All neuropeptides and reference drug semax show statistically significant influence on the amnesia caused by scopolamine administration. It st nd appear in the improving of memory encoding (1 memory stage), storage (2 rd memory stage) and retrieval (3 memory stage). At the conditions of scopolamine-induced amnesia investigated rd neuropeptides stimulates 3 memory stage too. This activity increases in the sequence semax < КК-10 = КК-1 < КК-2 < КК-3 = КК-5. The statistical analysis indicates a lack of significant difference between anti-amnestic activity of neuropeptides. The ability of investigated neuropeptides to stimulate of mice‘s mnemonic functions at conditions of m-cholinoblocker scopolamine- induced amnesia witness about their expressive nootropic properties. The mechanism of it perhaps consist in a positive influence on the brain cholinergic transmission. The obtained results demonstrate absent of peculiarity of investigated neuropeptides influence on the memory stages. It different the neuropeptides from known nootropic drugs as well as piracetam, which influences st only on the memory encoding (1 memory stage) and used in higher doses. In recent years, the role of melatonin in the human body attracts attention of doctors and scientists. This is due to multiple effects of melatonin in the normal functioning of the body: antioxidant, immunomodulatory, and influence at the reproductive system. In mammals the epiphysis is a source of melatonin, the so- called pineal melatonin. The rhythm of the production of melatonin by the pineal gland is the circadian character. It is known that in the first years of life synthesis of melatonin in apps increases, and then throughout life is gradually and slowly reduced. The rate of decrease concentration of melatonin in the body is directly correlated with indicators of longevity. It is known that the elderly with deficiency of melatonin have more disease of cardiovascular, nervous, endocrine and other systems with severe course.

These reflections are also present in the snapshot of (A) where a double-diffraction path that leads to the (222) re¯ ¯ flection over (113) and (111) is marked¯ ¯ ¯ by arrows purchase viagra soft with amex. Note that the overall intensity distribution in (B) and (C) is far from the “nearly leveled out” intensity distribution that may be caused by strong multiple scattering effects in experimental electron diffraction patterns cheap 100mg viagra soft free shipping. In addition order 100mg viagra soft with visa, both figures have essentially the same intensity ordering between the strongest and weakest reflections buy discount viagra soft on-line. To appreciate a beneficial side effect of the precessing primary electron beam, note that all electron diffraction patterns arise from the same nanocrystal area in the same crystallographic orientation. Systematic dynamical interactions along such rows are not suppressed by the precession movement of the primary electron beam. More reflections allow for least-squares fits to larger sys- tems of inhomogeneous linear equations. This results in more precise determina- tions of projected reciprocal lattice geometries. To appreciate a side effect of the precessing primary beam, note that all of the electron diffraction patterns of this figure arise from the same nanocrystal area with the same initial beam tilt misalignment with respect to the optical axis of the transmission electron microscope. The reflections are kinematically forbidden for silicon, but they are rather strong in all diffraction patterns [Figs. The special term “pertur- bation reflections” has been suggested (79) for such reflections and their intensity is due to an electron diffraction equivalent of the Renninger (“Umweganregungs”) effect of X-ray diffraction. The subsequent diffraction of the (113) beam on the (111)¯ ¯ ¯ net plane results, for example, in the (222) reflection. This can partly be explained by the precession geometry, which tends to excite whole systematic rows at once. As demonstrated in Figures 5 to 7, kinematically forbidden reflections, for example, ± and or reflections of silicon, are frequently present in electron diffraction patterns as a result of multiple dynamical scattering. The ±(002) reflections in the [110] orientation of silicon arise mainly from the double scattering by the ±(111)¯ ¯ and ±(111)¯ reflections. Since these ±(111)¯ ¯ and ±(111)¯ reflections possess the largest net plane spacing, the effect of the geometri- cal part of the Lorentz factore on their intensities will be rather significant for low Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope 291 Zero precession 1. All diffraction patterns were recorded close to the amorphized edge region of the sample that borders on the vacuum region within the microscope. The concentric rings in all diffraction patterns arise from the above-mentioned amorphized edge region. The effect of the geometrical part of the Lorentz factore seems to dominate over its structure–thickness- dependent part for this thin crystal and may explain the initial absolute increase of the intensity of the kinematically forbidden ±(002) reflections with precession angle. One member of this pair of reflections is marked by an arrow in each diffraction pattern. Figure 8 provides a comparison of the effect of the precession angle on the intensity of the ±(002), ±(111), and ±(111) reflections for the 6-nm thin silicon nanocrystal of Figure 7 with the corresponding dependency of the thickest silicon nanocrystal of that range, that is, the 56-nm thick silicon nanocrystal of Figure 6. Principally different dependencies of the integrated intensities of kinematically for- bidden and “allowed” reflections on the precession angle for both thicknesses are revealed in Figure 8. While there is an exponential decay of the intensities for the ±(002) reflections of the thick crystal and an analogous decay with nearly the same slope between 1. These principally different dependencies may allow for a quite unambigu- ous identification of some of the kinematically forbidden reflections and could be utilized for advanced structural fingerprinting. The normalization was performed by dividing the maximal peak intensity of the reflections by the maximal peak intensity of the primary beam. The relative large difference in the intensities of members of the two Friedel pairs in (A) is due to the recording of the diffraction patterns close to the amorphized edge region of the sample, bordering on the vacuum region in the microscope (see caption of Fig. The program “Space Group Determinator” from the Calidris companyf supports such identifi- cations (82). This effect is also demonstrated by the integrated peak intensities of the ±(111) Friedel pair reflections in Figure 8(B). Dorset’s correction scheme (37) may, therefore, be developed on the basis of two experimental data sets that differ with respect to their “effec- tive curvature” of the Ewald sphere but are recorded successively from the same crystalline sample area. The extraction of information on the projected reciprocal lattice geometry is very similar for both sources of structural data. One of these parameters 294 Moeck and Rouvimov is the distance of the reflection to the reflection 000, in other words, the length of the reciprocal lattice vector of this reflection. The other parameter is the acute angle this reflection makes with another reflection. The remaining parameter is the length of the other reciprocal lattice vector that was used in order to define the (acute) “interfringe angle. Experimen- tal plots of projected reciprocal lattice geometry are thus independent of this orien- tation. Another advantage of this definition of the position parameters of reflections is connected to the ways in which lattice centering and space group symmetry ele- ments with glide component that result in kinematically forbidden reflections are dealt with in such plots. For now, it suffices to say that the experimental plots will represent the whole projected reciprocal lattice geometry in a consistent manner. The latter plots can be calculated “on the fly” over the Internet from our mainly inorganic subset (15) of the Crystallography Open Database (16–18) and contain all of the data points for all of the zone axes of a crystalline material up to a predefined resolution in reciprocal space. Identifying a crystal from its projected reciprocal lattice geometry is, thus, frequently equivalent to finding the 2D data points of the experimental plot within the theoretical lattice-fringe fingerprint plot. Figure 9 shows the theoretical lattice-fringe fingerprint plot for the mineral rutile for a 0. Screw axes and glide planes result in systematic absences of reflections in 2D projections of the reciprocal lattice geometry and are revealed in “kinematic lattice-fringe fingerprint plots” by missing rows [compare Figs. The so-called “Gjønnes and Moodie dynamically forbidden reflections” (83) are shown in dynamical lattice-fringe fingerprint plots [Fig. The other type of system- atic absences of reflections in 2D projections of reciprocal lattice geometries, which are due to 3D Bravais lattice centerings, results in systematic absences of entire rows in lattice-fringe fingerprint plots independent of the “kinematic” or “dynamic” type of these plots. While there are two data points in lattice-fringe fingerprint plots for reflections with different spacings, the crossing of two symmetrically reflections results in just one data point (because the latter possess by symmetry the same spacing). All of the resolvable lattice fringes and reflections up to the appropriate resolution will be included for a certain crystal Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope 295 Lattice-fringe fingerprint plot for rutile; Ti O2 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 0 3. Note the (Gjønnes and Moodie) dynamically forbidden reflections, for example, in the case of rutile in the exact [001] orientation, are included in the (two-beam) dynamic diffraction limit plot. Note the characteristically different distribution of the two-dimensional data points in both plots and that the abscissas are on different length scales. Structural Fingerprinting of Nanocrystals in the Transmission Electron Microscope 297 structure into these plots. The appearance of lattice-fringe fingerprint plots is, thus, both crystalline material and reciprocal space resolution specific (Figs. Figure 10(A) shows a theoretical lattice-fringe fingerprint plot that has been calculated for vanadium oxide nanotubes, a crystalline material that did not give a characteristic X-ray powder diffraction fingerprint (Fig. Due to the rather large unit cell dimensions of the vanadium oxide nanotubes (29), an older transmission electron microscope with a very modest Scherzerb resolution of 0. A modern analytical transmission electron microscope with a Scherzerb resolution of 0. Figure 10(B) shows a theoretical lattice-fringe fingerprint plot for the min- eral pseudo-brookite, for which a characteristic X-ray powder diffraction fingerprint was shown as Figure 1. From the comparison of Figures 10(A) and 10(B), one can conclude that lattice-fringe fingerprinting works for both types of crystalline mate- rials, those that do not (Fig. An initial search in a database of theoretical lattice-fringe fingerprints that is based on the 2D positions of data points in lattice-fringe fingerprint plots alone may result in several candidate structures. In the following steps, the search can be made more discriminatory both by trying to match crystallographic indices to the 2D positions and by determining the projected symmetry. Because one will always project along one zone axis, all indices of the reflec- tions must be consistent with a certain family of zone axes. As far as the lattice- fringe fingerprint plots are concerned, this follow-up search is equivalent to assign- ing crystallographic indices to the 2D data points. Each (vertical) column of data points in a lattice-fringe fingerprint plot corresponds to one family of reflections (net planes). Discrete points on a second x-axis in a lattice-fringe fingerprint plot can, therefore, be labeled with the respective Miller indices, , of a family of reflections. Each (horizontal) row of data points in a plot such as Figures 9 and 10, on the other hand, belongs to a family of zone axes. Discrete points on a second y-axis of such a plot can, thus, be labeled with the respective Miller indices, , of a family of zone axes. The cross product of the Miller indices of two data points from two different columns (representing two different reciprocal spacings) that are also located within the same row (representing one interfringe angle) gives the zone axis symbol, = × . While each family of reflections will show up only once on such a second x-axis, the same family of zone axis symbols may be showing up multiple times on such a second y-axis.