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1.
Due to the structure of acylhydrazones both by the pharmacophore –CO–NH–N= group and by the different substituents present in the molecules of compounds of this class, various pharmacological activities were reported, including antitumor, antimicrobial, antiviral, antiparasitic, anti-inflammatory, immunomodulatory, antiedematous, antiglaucomatous, antidiabetic, antioxidant, and actions on the central nervous system and on the cardiovascular system. This fragment is found in the structure of several drugs used in the therapy of some diseases that are at the top of public health problems, like microbial infections and cardiovascular diseases. Moreover, the acylhydrazone moiety is present in the structure of some compounds with possible applications in the treatment of other different pathologies, such as schizophrenia, Parkinson’s disease, Alzheimer’s disease, and Huntington’s disease. Considering these aspects, we consider that a study of the literature data regarding the structural and biological properties of these compounds is useful.  相似文献   

2.
用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.  相似文献   

3.
M. Remko 《Chemical Papers》2007,61(2):133-141
Computational chemical methods have been used to correlate the molecular properties of the 10 ACE inhibitors (captopril, enalapril, perindopril, lisinopril, ramipril, trandolapril, quinapril, fosinopril, benazepril, and cilazapril) and some of their active metabolites (enalaprilat, perindoprilat, ramiprilat, trandolaprilat, quinaprilat, fosinoprilat, benazeprilat, and cilazaprilat). The computed pK a values correlate well with the available experimental values. In the dicarboxylic ACE inhibitors, the carboxyalkyl carboxylate group of the ACE inhibitors studied is more acidic than the C-terminal carboxylate. However, at physiological pH = 7.4 both carboxyl groups of ACE inhibitors are completely ionized and the dicarboxyl-containing ACE inhibitors behave as strong acids. The available experimental partition coefficients of these ACE inhibitors investigated are well reproduced by the neural network-based ALOGPs and the fragment-based KoWWiN methods. All parent drugs (and prodrugs), with the exception of fosinopril, are compounds with low lipophilicity. Calculated pK a, lipophilicity, solubility, absorption, and polar surface area of the most effective ACE inhibitors for the prevention of myocardial infarction, perindopril and ramipril, were found similar. Therefore, it is probable that the experimentally observed differences in the survival benefits in the first year after acute myocardial infarction in patients 65 years of age or older correlate closely to the physicochemical and pharmacokinetic characteristics of the specific ACE inhibitor that is used.  相似文献   

4.
田圆  赵倩莹  胡靖  周辰  缪灵  江建军 《化学进展》2012,24(4):512-522
大面积高质量石墨烯的制备对石墨烯电子特性及石墨烯基纳器件相关研究有重要意义。本文综述了近几年来衬底上制备石墨烯的相关实验以及衬底与石墨烯相互作用研究的重要进展。目前,采用化学气相沉积、外延生长等方法可在衬底表面上制备出较大面积、高质量的石墨烯材料。衬底与石墨烯相互作用和界面间晶格匹配、原子成键及电荷转移等密切相关,其对吸附石墨烯的几何结构、能带结构及电子特性等产生明显影响。实验与理论计算的结合可望加深衬底与石墨烯作用机理的理解,指导衬底上石墨烯制备及改性的进一步研究。  相似文献   

5.
Seventy-three samples of alcoholic beverages and juices that were purchased on the Polish market and home-made were analyzed for their elemental profiles. The levels of 23 metals were determined by ICP-MS (Ag, Ba, Bi, Cd, Co, Cr, Li, Mn, Ni, Pb, Sr and Tl), ICP-OES (Al, B, Ca, Cu, Fe, K, Mg, Na, Ti and Zn) and CVAAS (Hg) techniques in twenty-five samples of ciders widely available on the Polish market; six samples of home-made ciders; two samples of juices used in the production of these ciders; and forty samples of low-percentage, flavored alcoholic beverages based on beer. The gathered analytical data confirmed that the final elemental fingerprint of a product is affected by the elemental fingerprint of the ingredients used (apple variety) as well as the technology and equipment used by the producer, and in the case of commercial ciders, also the impact of type of the packaging used was proven. These factors are specific to each producer and the influence of the mentioned above parameters was revealed as a result of the performed analysis. Additionally, the inclusion of the home-made ciders in the data set helped us to understand the potential origin of some elements, from the raw materials to the final products. The applied statistical tests revealed (Kruskal–Wallis and ANOVA) the existence of statistically significant differences in the concentration of the following metals: Ag, Al, B, Bi, Co, Cr, Cu, Fe, K, Li, Mg, Na, Ni, Ti and Zn in terms of the type of cider origin (commercial and home-made). In turn, for different packaging (can or bottle) within one brand of commercial cider, the existence of statistically significant differences for Cu, Mn and Na was proved. The concentrations of all determined elements in the commercial cider from the Polish market and home-made cider samples can be considered as nontoxic, because the measured levels of elements indicated in the regulations were lower than the allowable limits. Moreover, the obtained results can be treated as preliminary for the potential authentication of products in order to distinguish the home-made (fake) from the authentic products, especially for premium-class alcoholic beverages.  相似文献   

6.
Fructus Corni (FC), as a promising Chinese medicinal herb, has aroused considerable interest. Generally, FC needs to be processed according to the limited standard policy in China before clinical application, while the investigations on the specific processing methods (such as wine steaming or high-pressure wine steaming) are unclear. A comprehensive metabolomics strategy based on integrated non-targeted metabolomics and targeted glycomics in this paper was implemented to investigate the influences of the different processing technologies such as steaming, wine steaming, high-pressure steaming, high-pressure wine steaming, wine immersion, and wine stir-frying on FC, respectively. UHPLC-Q-TOF-MS/MS was employed for identifying and distinguishing the secondary metabolites. A total of 85 components were identified in all groups. The results of PCA score plots showed that the crude and processed samples had a complete separation, and wine steamed and high-pressure wine steamed samples could be a category, indicating that the two processed products had a similar quality. Multiple chromatography including HPLC (C18)-PDA, HPLC (NH2)-ELSD, and HPGPC-ELSD was used for determining the molecular weight distributions, the monosaccharide compositions of polysaccharides, and the contents of free monosaccharides and oligosaccharides. The results indicated that the content and composition of saccharides were different in crude and different processed FC. The polysaccharides were composed of fucose, arabinose, galactose, glucose, galacturonic acid, mannose and rhamnose, and the free monosaccharides were composed of fucose, arabinose, galactose, glucose, mannose, rhamnose and fructose in all FC samples. The PCA score plots of the glycomics indicated that the crude and high-pressure wine steamed FC could be a category, showing that the two groups had similar chemical compositions. Ultimately, the simulation processing experiments indicated that the transformation of morroniside, polysaccharides, oligosaccharides, fructose, and glucose to 5-HMF through the reactions of dehydration and deglycosylation was the potential mechanism of enhancing the effects by processing. Conclusionly, the saccharides should be investigated as thoroughly as the secondary metabolites, and the high-pressure wine steamed FC could be an alternative to wine steamed FC.  相似文献   

7.
This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed.  相似文献   

8.
The diffusion coefficients of a series of symmetrical tetraalkyltins (tetramethyltin, tetraethyltin, tetrapropyltin, tetrabutyltin, tetradodecyltin) of the gases argon, krypton, xenon, methane, and tetramethylmethane and of carbon tetrachloride and tetraethylmethane in hexane, decane, and tetradecane at 25°C have been determined using the Taylor dispersion technique. Diffusion coefficients for the gases in acetone, 2-propanol, 1-butanol, and 1-octanol were also determined. Deviations from the predictions of Stokes' law were found to be large, and the magnitude of the deviation can be directly related to solute size. The predictions of the Hubbard-Onsager equation were tested using the diffusion data.  相似文献   

9.
宋锐 《高分子科学》2006,(5):515-528
Thin films of incompatible polymer blends can form a variety of structures during preparation and subsequent annealing process. For the polymer blend system consisting of polystyrene and poIy(styrene-co-p-bromo-styrene), i.e., PS/PBrxS, its compatibility could be adjusted by varying the degree of bromination and the molecular weight of both components comprised, in this paper, surface chemical compositions of the cast and the annealing films were investigated by X-ray photoelectron spectroscopy (XPS) and contact angle measurement; meanwhile, surface topographical changes are followed by atomic force microscopy (AFM). In addition, substantial attention was paid to the effect of annealing on the morphologic variations induced by phase separation and/or dewetting of the thin film. Moreover, the influences of the molecular weight, Aw, as well as the brominated degree, x%, on the sample surface are explored systematically, and the corresponding observations are explained in virtue of the Flory-Huggins theory, along with the dewetting of the polymer thin film.  相似文献   

10.
多极性基有机添加物对非离子表面活性剂溶液雾点的影响   总被引:1,自引:0,他引:1  
吴锦屏  顾惕人 《化学学报》1995,53(10):958-960
测定了甲酸、乙酸、草酸、甲醇、乙醇、丙醇、乙二醇、丙三醇和葡萄糖对非离子表面活性剂Triton X-100和Triton X-114水溶液雾点的影响。低级脂肪酸和醇能使雾点升高, 升高的程度随酸或醇的碳氢链的增长而增加。但若在增加分子碳氢链长或碳氢部分的同时引入更多的羧基或羟基, 则雾点升高的效应将受到抑制。当极性基数目较多时, 可导致雾点显著下降。  相似文献   

11.
Despite unifloral honeys from Sardinia, Italy, being appreciated worldwide for their peculiar organoleptic features, their elemental signature has only partly been investigated. Hence, the principal aim of this study was to measure the concentration of trace and toxic elements (i.e., Ag, As, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Sb, Sn, Sr, Te, Tl, V, and Zn) in four unifloral honeys produced in Sardinia. For this purpose, an original ICP-MS method was developed, fully validated, and applied on unifloral honeys from asphodel, eucalyptus, strawberry tree, and thistle. Particular attention was paid to the method’s development: factorial design was applied for the optimization of the acid microwave digestion, whereas the instrumental parameters were tuned to minimize the polyatomic interferences. Most of the analytes’ concentration ranged between the relevant LoDs and few mg kg−1, while toxic elements were present in negligible amounts. The elemental signatures of asphodel and thistle honeys were measured for the first time, whereas those of eucalyptus and strawberry tree honeys suggested a geographical differentiation if compared with the literature. Chemometric analysis allowed for the botanical discrimination of honeys through their elemental signature, whereas linear discriminant analysis provided an accuracy level of 87.1%.  相似文献   

12.
Although noble metals are still widely used in electroanalysis, a plethora of different nonconventional metals is now enriching the panorama of materials acting as the electrochemical transducer in sensing systems. In particular, Ti, Cu, Co, Fe, Mo, Ta, W, Rh, Bi, Sb, Te and Pb are discussed here in view of their peculiar physicochemical properties and of the interesting electrocatalytic activities ascribable to these elements and to the relevant metal oxide ultrathin films that spontaneously form at the electrode–solution interface. This behaviour, exploitable in electroanalysis for the detection of a number on analytes, is often accompanied by low price and high resistance to corrosion and to abrasion characterising these materials. These peculiarities encourage the possible use of the cited metals in a wide number of analytical frames, ranging from process control to bioimplantable sensing systems.  相似文献   

13.
锂硫电池具有理论能量密度高等优势,被认为是最有前景的一类新型二次电池.硫正极存在硫和硫化锂的导电性差、可溶性多硫化物的扩散/穿梭、循环过程中硫的体积膨胀以及氧化还原过程慢等问题,严重制约着电池的活性和循环稳定性.设计“蛋黄-蛋壳”结构纳米反应器应用于锂硫电池正极,可通过调控其“蛋黄”、“蛋壳”和“空腔”结构缓解充放电过程中电极的体积变化,为离子/电子输运提供快速通道,强化对多硫化物的吸附和催化转换作用等,进而提高电极的活性和循环性能,有利于推进锂硫电池的商业化进程.本文总结了“蛋黄-蛋壳”结构纳米反应器的设计和调控策略,包括单核-单壳、单核-多壳、多核-单壳以及多核-多壳等,并结合锂硫电池的工作特点和目前应用存在的问题,对未来发展前景进行了展望.  相似文献   

14.
Wine is one of the most popular alcoholic beverages. Therefore, the control of the elemental composition is necessary throughout the entire production process from the grapes to the final product. The content of some elements in wine is very important from the organoleptic and nutritional points of view. Nowadays, wine studies have also been undertaken in order to perform wine categorization and/or to verify the authenticity of products. The main objective of this research was to evaluate the influence of the chosen factors (type of wine, producer, origin) on the levels of 28 elements in 180 wine samples. The concentration of studied elements was determined by ICP-MS (Ag, B, Ba, Be, Bi, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Rb, Sb, Sn, Sr, Te, Tl, U, Zn), ICP-OES (Ca, Fe, K, Mg, Ti), and CVAAS (Hg) techniques in 79 red, 75 white, and 26 rose wine samples. In general, red wines contained higher values of mean and median of B, Ba, Cr, Cu, Mn, Sr and Zn in contrast to other wine types (white and rose). In white wines (when compared to red and rose wines) higher levels of elements such as Ag, Be, Bi, Cd, Co, Li, K and Ti were determined. In contrast, rose wines were characterized by a higher concentration of Fe and U. The study also revealed that in the case of 18 samples, the maximum levels of some metals (Cd—8 samples, Pb—9 samples, Cu—1 sample) were slightly exceeded according to the OIV standards, while for Zn and Ti in any wine sample the measured concentrations of these metals were above the permissible levels. Thus, it can be stated that the studied wines contained, in general, lower levels of heavy metals, suggesting that they should have no effect on the safety of consumption. The results also showed higher pH level for red wines as a consequence of the second fermentation process which is typically carried out for this type of wine (malolactic fermentation). The highest median value of pH was reported for Merlot-based wines, while the lowest was for Riesling. It is assumed that dry Riesling has a higher content of tartaric and malic acid than dry Chardonnay grown in the same climate. From all of the studied countries, wines from Poland seemed to present one of the most characteristic elemental fingerprints since for many elements relatively low levels were recorded. Moreover, this study revealed that also wine samples from USA and Australia can be potentially discriminated from the rest of studied wines. For USA the most characteristic metal for positive identification of the country of origin seems to be uranium, whereases for Australia – strontium and manganese. Based on the highly reduced set of samples, it was not possible to differentiate the studied wine products according to the grape variety other than Syrah, and partially Chardonnay. Since all the Syrah-based samples originated from the same country (Australia) thus, the observed grouping should be more related with the country of origin than the grape variety.  相似文献   

15.
To understand the influence of impurities and rare earth elements in nature on the intergranular corrosion of the zinc-aluminum alloys, taking efficient methods to retard the inter granular corrosion, the atomic cluster of α phase grain boundary including impurities (Pb, Sn, Cd), rare earth elements (La, Y) and phase grain was constructed by computer programming based on the coincidence-site lattice theory. The recursion method was used to calculate the charge transfer over the grain boundary of α phase, and discuss influence of impurities (Pb, Sn, Cd) and Rare Earth elements (La, Y) on the electrode-potential of Zn and Al. The results shows that impurity elements (Pb, Sn, Cd) can increase the charge transfer between atoms over the grain boundary, leading to the large difference of electrode-potential between Zn and Al. Therefore the eroding is speeding up, but the RE element can reduce the charge transfer between atom sover the grain boundary, and lower the difference of electrode-potential between Zn and Al. Thus RE element is of the role of restraining the inter granular corrosion of zinc-aluminum alloys.  相似文献   

16.
殷果  钱佩雯  李秋璠梓  金静  刘玲  张金专 《色谱》2022,40(5):401-408
火灾是影响公共安全最为常见的灾害之一,而放火更是严重威胁人民群众生命财产安全,属于典型的暴力犯罪.犯罪嫌疑人为了达到有效快速放火的目的,往往使用助燃剂实施放火,因而助燃剂的检验鉴定对于认定火灾性质起着至关重要的作用.然而火场情况复杂,容易对助燃剂物证检验鉴定产生较大干扰.在火灾发生发展的过程中,火场高温热环境会作用于已...  相似文献   

17.
The isothermal crystallizations of three kinds of commercial isotactic polypropylene have been studied by DSC and rheometric experiments, in a range of temperatures where the rate of crystallization is moderate. As the crystallization proceeds, volume contraction induces tensile force upon the parallel plates. The tensile force relaxed quickly in liquid states,but after a critical amount of the relative crystallinity, it starts to accumulate in the static test, that is, with the motionless parallel plates. A new method to determine the liquid-solid transition by the static tensile force is proposed and compared with two dynamic methods of detecting liquid-solid transition, that is, the power-law modulus theory and the yield modulus model. The tensile force method predicted considerably earlier transition than the dynamic methods, and the corresponding DSC data indicate relative crystallinity of larger than 0.2 at the transition times. The limitation of dynamic methods and other possible errors have been analyzed. While the dynamic methods are suitable for slow crystallization, the tensile force method is more appropriate for the crystallization of moderate rates. Moreover, it has the advantage of almost not disturbing the crystallizing materials before the transition.  相似文献   

18.
Cannabis sativa L. is an annual species cultivated since antiquity for different purposes. While, in the past, hemp inflorescences were considered crop residues, at present, they are regarded as valuable raw materials with different applications, among which extraction of the essential oil (EO) has gained increasing interest in many fields. The aim of the present study is the evaluation of the yield and the chemical composition of the EO obtained by hydrodistillation from eleven hemp genotypes, cultivated in the same location for two consecutive growing seasons. The composition of the EOs was analyzed by GC–MS, and then subjected to multivariate statistical analysis. Sesquiterpenes represented the main class of compounds in all the EOs, both in their hydrocarbon and oxygenated forms, with relative abundances ranging from 47.1 to 78.5%; the only exception was the Felina 32 sample collected in 2019, in which cannabinoids predominated. Cannabinoids were the second most abundant class of compounds, of which cannabidiol was the main one, with relative abundances between 11.8 and 51.5%. The statistical distribution of the samples, performed on the complete chemical composition of the EOs, evidenced a partition based on the year of cultivation, rather than on the genotype, with the exception of Uso-31. Regarding the extraction yield, a significant variation was evidenced among both the genotypes and the years of cultivation.  相似文献   

19.
During pregnancy, women undergo metabolic and physiological changes, and their needs are higher, to maintain growth and development of the fetus. If the nutritional status of the expectant mother is not satisfactory, some maternal and neonatal complications can occur. In the second and third trimester of pregnancy, there is a reserve of nutrients in the fetus that can be utilized after birth; thereby, children present an accelerated growth in the first years of life, which is a proven response to the available nutrition pattern. However, if such a pattern is insufficient, there will be deficits during development, including brain function. Therefore, despite many recent published works about gestational nutrition, uncertainties still remain on the mechanisms of absorption, distribution, and excretion of micronutrients. Further elucidation is needed to better understand the impacts caused either by deficiency or excess of some micronutrients. Thus, to illustrate the contributions of minerals during prenatal development and in children, iodine, selenium, iron, zinc, calcium, and magnesium were selected. Our study sought to review the consequences related to gestational deficiency of the referred minerals and their impact on growth and development in children born from mothers with such deficiencies  相似文献   

20.
The acceleration of industrialization and the continuous upgradation of consumption structure has increased the atmospheric content of CO2 far beyond the past levels, leading to a serious global environmental problem. Photocatalytic reduction of CO2 is one of the most promising methods to solve the problem of rising atmospheric CO2 content. The core of this technology is to develop efficient, environment-friendly, and affordable photocatalysts. A photocatalyst is a semiconductor that can absorb photons from sunlight and produce electron-hole pairs to initiate a redox reaction. Owing to their low specific surface areas, significant electron-hole recombination, and less surface-active sites, bulk photocatalysts are not satisfactory. Ultrathin layered materials have shown great potential for photocatalytic CO2 reduction owing to their characteristics of large specific surface area, a large number of low-coordination surface atoms, short transfer distance from the inside to the catalyst surface, along with other advantages. Photoexcited electrons only need to cover a short distance to transfer to the nanowafer surface, and the speed of migrating electrons on the nanowafer surface is much higher than that in the layers or in the bulk catalyst. The ultrathin structure leads to significant coordinative unsaturation and even vacancy defects in the lattice structure of the atoms; while the former can be used as active sites for CO2 adsorption and reaction, the latter can improve the separation of the electron-hole pair. This review summarizes the latest developments in ultrathin layered photocatalysts for CO2 reduction. First, the photocatalytic reduction mechanism of CO2 is introduced briefly, and the factors governing product selectivity are explained. Second, the existing catalysts, such as g-C3N4, black phosphorus (BP), graphene oxide (GO), metal oxide, transition metal dichalcogenides (TMDCs), perovskite, BiOX (X = Cl, Br, I), layered double hydroxide (LDH), 2D-MOF, MXene, and two-dimensional honeycomb-like Ge―Si alloy compounds (gersiloxenes), are classified. In addition, the prevalent preparation methods are summarized, including mechanical stripping, gas stripping, liquid stripping, chemical etching, chemical vapor deposition (CVD), template method, self-assembly of surfactant, and the intermediate precursor method of lamellar Bi-oleate complex. Finally, we introduced the strategy of improving photocatalyst performance on the premise of maintaining its layered structure, including the factors of thickness adjustment, doping, structural defects, composite, etc. The future opportunities and challenges of ultrathin layered photocatalysts for the reduction of carbon dioxide have also been proposed.  相似文献   

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