First synthesis and characterization of SRR/RSS-Ezetimibe

The two stereoisomers, SRR-Ezetimibe 2 and RSS-Ezetimibe 3 are related substances of the cholesterol absorption inhibitor drug Ezetimibe 1. Herein, we present an efficient and practical synthesis approach to deliver these two stereoisomers for the first time, and a proof of SRR-Ezetimibe 2 by single-crystal X-ray analysis. Our research will be of immense help for organic chemists to study the impurity profile of Ezetimibe 1.     

Processing and characterization of LDPE/starch/PCL blends

Low-density polyethylene/plasticized starch/polycaprolactone blends were processed by conventional extrusion, injection molding, and film blowing techniques. The glass transition temperatures of plasticized starch were determined using differential scanning calorimetry. The blends were characterized by mechanical property measurements and scanning electron microscopy. The blend properties were found to depend not only on composition but also on the generated morphology. In films the fine dispersion of polycaprolactone phase in the polyethylene/starch matrix resulted in mechanical property increase, while in injection specimens there was property decrease due to phase coalescence. It appears that the different conditions existing at the two different shaping processes i.e. film blowing and injection molding could account for the final obtained morphology.     

TG/DSC/FTIR characterization of linear geranyl diesters

The synthesis, thermal behavior, and characterization of the decomposition products of linear geranyl diesters: digeranyl succinate, digeranyl glutarate, digeranyl adipinate, and digeranyl sebacinate were presented. The linear geranyl diesters were prepared in direct esterification process of a molar stoichiometric ratio of geraniol and suitable acidic reagent in solvent-free medium at 130 °C using butylstannoic acid as a catalyst. Their structure was confirmed based on FTIR, ¹H- and ¹³C-NMR spectra. It was proved that the use of tin catalyst allowed decreasing the reaction time and increasing the final conversion of substrates when compared to non-catalyzed process. It considerably simplifies the processing by reduction of the preparation cost and thus this new method of synthesis of aroma diesters may be attractive for practical applications. The thermal behavior of prepared compounds was studied by TG/DSC/FTIR coupled method. TG analysis showed that diesters are thermally stable up to temperatures above 200 °C. The DTG curves confirmed that these decomposition run as a single-stage process. The T _max1 were in the range of 294.5–313.8 °C depending on the aliphatic chain length (–CH₂–)_n in the structure of aroma diesters, which was in accordance with DSC data. The analysis of the gases evolved during heating of diesters in inert atmosphere indicated on the asymmetrical disrupt of their bonds. The cleavage of ester bond and O-geranyl bond was expected. It resulted in production of the mixture of derivatives of geraniol (acyclic and alicyclic monoterpene hydrocarbons) like myrcene, ocimene, or limonene as main decomposition products. In addition, the formation of anhydride, lactone, or ketone functionalities among the degradation products clearly confirmed the proposed degradation path of studied diesters.     

Thermal characterization of polypropylene/vermiculite composites

Vermiculite clay (VMT) was organically modified with a quaternary organic salt and added to polypropylene (PP). The compounds were prepared by melt intercalation using a twin extruder. The morphology of the composites was investigated through wide-angle X-ray diffraction (WAXD). The WAXD results suggested that exfoliation phenomena were found for the composites with modified clay. The thermal properties of the obtained composites were studied by means differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements. A variation in the crystallinity of PP was found. A significant increase of the thermal stability of PP was achieved in the presence of the modified VMT.     

Synthesis,bulk characterization,and surface characterization of p-hydroxystyrene/styrene copolymers

Styrene/p-hydroxystyrene copolymers were prepared from copolymers of styrene and p-benzyloxystyrene by cleavage of the ether bond. Nuclear magnetic resonance spectroscopy was used to characterize the polymers before and after the ether cleavage reaction. Reactivity ratios were calculated by applying the method of least squares to data generated from the Fineman–Ross equation (r₁ = 0.37, r₂ = 0.28). The surface chemistry of centrifugally cast films of the homopolymers and the copolymers was studied by using electron spectroscopy for chemical analysis (ESCA). The Zisman contact angle method was used to determine the critical surface tension in air for each polymeric surface. Water contents of hydrated films were determined gravimetrically. The polar character of the surface was shown to increase to a small degree with an increase in the p-hydroxystyrene component. Polymers with high p-hydroxystyrene contents did not exhibit pronounced hydrogel character.     

Electrical and spectroscopic characterization of metal/monolayer/Si devices

A simple technique for vibrational spectroscopy of metal/monolayer/silicon structures is applied to study the interaction of Au, Al, and Ti with alkane monolayers, either assembled onto thin oxides or directly attached to Si. The results are correlated with current-voltage and capacitance-voltage measurements. Alkane films on oxides are found to be robust with respect to the deposition of Au and Al and are partially consumed during the deposition of Ti. In contrast, alkoxy films directly attached to H-terminated Si via an ether linkage are displaced by all three metals. The vibrational data are positively correlated with the electrical data to establish an improved understanding of the interactions at the buried metal/monolayer interface. The results demonstrate extreme sensitivity of the monolayer/metal reactivity to the nature of the film/substrate bonding.     

ATR/FTIR characterization of Steinernema glaseri and Heterorhabditis indica

The use of Fourier transform mid-infrared spectroscopy with attenuated total reflection for characterizing entomopathogenic nematodes is evaluated for the first time. The resulting spectra of Steinernema glaseri and Heterorhabditis indica were compared with the spectrum of Caenorhabditis elegans. In the absorption spectra generated by the nematodes samples, the absorption bands were assigned to the molecular species and some important components were identified including triglycerides, trehalose, glycogen and collagen. Also, the use of star diagrams for the fingerprint section of nematode spectra for separating genera is discussed.     

Synthesis and characterization of polycyanurate/montmorillonite nanocomposites

The advantages of cyanate esters (CEs) versus competitor systems such as epoxies and polyimides, as well as the great reinforcing potential of organoclays properly dispersed into a polymeric matrix, have been examined in a series of polycyanurate (PCN)/montmorillonite (MMT) nanocomposites prepared under appropriate polymerization conditions. The curing schedule applied resulted in gradual propagation of polymerization. Through this procedure, the intragallery curing rate becomes comparable to the extragallery one, allowing intercalation before gelation. Systems with clay loadings from 1 to 3% per weight were synthesized, and their morphology and mechanical properties were studied by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), wide angle X‐ray scattering (WAXS), dynamic mechanical analysis (DMA), and tensile tests. Microscopy investigations revealed better dispersion for the 3 wt % system compared to smaller concentrations, in which aggregation and, in some cases, agglomeration were the conspicuous features. Roughness and area analyses revealed more homogeneous dispersion for this nanocomposite. Topology and 3D‐phase images further suggested considerable reduction of the average particle diameters. WAXS analysis showed that the interlayer spacing of nanocomposites was increased compared to pristine MMT, indicating the formation of intercalated structures. On the other hand, tensile strength and elongation at break values displayed abrupt diminution with MMT addition, while Young's modulus exhibited a slight but systematic increment with MMT content. The decreasing glass transition tendency observed for small clay loadings was reversed in the case of 3 wt %, while secondary transitions were practically unaffected by the presence of MMT. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1036–1049, 2008     

Thermal characterization of usnic acid/collagen-based films

The purpose of this study was to evaluate the physical–chemical properties of collagen (CL) and usnic acid/collagen-based (UAC) films, using differential thermal analysis (DTA), thermogravimetry (TG/DTG), infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Both films were prepared by casting process using polyethylene glycol 1500 (PEG 1500) as plasticizer. In the spectrum of UAC, similar bands of the usnic acid are observed, indicating that the polymerization (film formation) did not affect the stability of the drug. Distinctly, DTA curve of UAC did not show an endothermic peak at 201 °C, indicative that the drug was incorporated into the polymeric system. These results were corroborated by the scanning electron microscopy (SEM). The TG/DTG curves of UAC presented a different thermal decomposition profile compared to the individual compounds and CL. These findings suggest the occurrence of molecular dispersion or solubilization of the drug in the collagen film.     

Pt@Ag/Pt复合型纳米颗粒的合成与表征

通过吸附在铂纳米颗粒表面的氢交替还原硝酸银和氯铂酸,得到了复合型纳米颗粒Pt@Ag／Pt,用紫外-可见吸收光谱（UV-Vis）、透射电子显微镜（TEM）、X-射线衍射（XRD）对其进行了表征。通过氢化催化苯甲醛反应,由于Pt与Ag双金属间的协同效应,其催化活性较纯铂好。     

Pd-Ag/PTFE复合膜的制备及表征

本文以不同孔径的聚四氟乙烯（PTFE）为基膜，采用化学镀法分别将Ag、Pd沉积到PIFE膜孔及膜面上，制得了镀层均匀、结合力较好的Pd-Ag／PTEE复合膜，并考察了PTFE基膜孔径对镀层结合力的影响，以及化学镀工艺对金属钯沉积速率、复合膜孔结构和截面电阻率的影响。结果表明，适当的基膜孔结构有利于提高镀层结合力；PTFE膜经化学镀修饰后，孔径减小，孔径分布变窄，孔隙率降低，膜截面电阻率降低10^6数量级，且孔径减小顺序与截面电阻率减小顺序一致。     

Preparation and characterization of titania/tetratitanate nanocomposites

Nanocomposite titania/tetratitanate particles were prepared by utilizing the electrostatic interaction of the colloidal tetratitanate nanosheets and TiO₂ powders through dispersing TiO₂ into tetratitanate solution at pH4. The samples were characterized by X-ray powder diffraction, transmission electron microscopy, chemical analysis, and photocatalytic activity measurement. The crystallites of Ti₄O₉^2? in the form of tetratitanate nanosheets have lateral size around 100 nm. The visible light responsive photocatalytic activity of rutile nanoparticles could be improved by forming nanocomposite with layered tetratitanate. The high specific surface area of this kind of composite and a certain amount of mesopores in nanocomposite powder could be responsible for better performance in the NO elimination.     

Preparation and characterization of NaCS-CMC/PDMDAAC capsules

A novel capsule system composed of sodium cellulose sulfate (NaCS), carboxymethyl cellulose (CMC) and poly[dimethyl(diallyl)ammonium chloride] (PDMDAAC) was prepared for improving the properties of NaCS/PDMDAAC capsules. The process parameters, such as CMC concentration (0, 2, 4, 6 and 8 g/L), NaCS concentration (20, 25, 30, 35 and 40 g/L), PDMDAAC concentration (20, 30, 40, 50, 60, 70 and 80 g/L), reaction time and temperature were investigated to understand their effects on the diameter, membrane thickness and mechanical strength of capsules. The optimum operation conditions for preparing NaCS–CMC/PDMDAAC capsules were determined as 6–8 g/L CMC, 35–40 g/L NaCS, 60 g/L PDMDAAC and polymerization for 30–40 min. Diffusion of substances with low molecular weight into capsules was investigated, and diffusion coefficients were calculated according to the developed model. The yeast of Candida krusei was chosen as representative cell to evaluate the effects of different cell loading on capsule mechanical strength. Meanwhile the encapsulated osmophilic C. krusei cells were cultured in 250 mL shaking flasks for 72 h to determine the cell leaking properties in short and long term.     

Synthesis and characterization of tri-block fluorinated-n-alkanes

A series of triblock semifluorinated n-alkanes of general formula F(CF₂)_n(CH₂)_m(CF₂)_nF (n = 6, 8 and m = 4, 6, 8) have been synthesized and characterized. The synthesis of triblock compounds was performed in two different ways according to the length of the hydrogenated moiety. Coupling of two molecules of β-(perfluoro-n-alkyl)ethyl iodides leads to the triblock materials F(CF₂)₆(CH₂)₄(CF₂)₆F and F(CF₂)₈(CH₂)₄(CF₂)₈F. The synthesis of compounds with larger hydrogenated part is accomplished in two steps by the addition of perfluoro-n-alkyl iodide F(CF₂)_nI to 1,5-hexadiene and 1,7-octadiene, respectively to give the diiodo-adducts which are subsequently deiodinated to the final triblock products F(CF₂)₆(CH₂)₆(CF₂)₆F, F(CF₂)₆(CH₂)₈(CF₂)₆F, F(CF₂)₈(CH₂)₆(CF₂)₈F and F(CF₂)₈(CH₂)₈(CF₂)₈F. The obtained triblock semifluorinated n-alkanes are characterized by low surface free energies with good lubricant properties usable as additives in ski-wax formulations.     

Synthesis and first characterization of N-alkyldiaminoresorcinols

We report the synthesis and first characterization of N-alkyldiaminoresorcinols (or 4,6-bis-dialkylaminobenzene-1,3-diols C₆H₂(NHR)₂(OH)₂) (10a, R = CH₂-2-Py; 10b, R = CH₂-3-Py; 10c, R = CH₂-4-Py) which result from one-pot stepwise reactions: (i) air-oxidation of diaminoresorcinol 3, (ii) transamination reaction leading to the corresponding functional 6π+6π quinonemonoimine zwitterions C₆H₂(NHR)₂(O)₂ (9a, R = CH₂-2-Py; 9b, R = CH₂-3-Py; 9c, R = CH₂-4-Py), (iii) reduction and re-aromatization in the presence of the corresponding primary amine bearing a pyridine moiety.     

PMMA/SiO_2/OV-POSS杂化材料的制备与表征

以乙烯基三氯硅烷为原料水解制得八乙烯基多面体低聚倍半硅氧烷(OV-POSS),将其与经KH570改性的SiO2溶胶和甲基丙烯酸甲酯(MMA)混合均匀,采用热固化的方法制得PMMA/SiO2/OV-POSS杂化材料,通过透射电镜、红外谱图、差热分析和热重分析对材料的微观结构以及热性能进行表征,结果表明:杂化材料结构均匀,有机相和无机相之间通过双键聚合的方式形成了共价键;杂化材料耐热性好,玻璃化转变温度比纯PMMA提高约72℃,分解温度提高约121℃。     

Growth and characterization of Si/Sb superlattices

Summary Artificial Si_m/Sb₁ superlattices (m=15, 30, 60) were grown by molecular beam epitaxy at very low temperatures (200°C). Rutherford backscattering spectroscopy revealed the superlattices to be single crystalline with min values of less than 0.04. X-ray diffraction clearly showed the superlattice structure. However, residual surface segregation still activated at the low temperatures employed leads to a spread out of Sb atoms into the subsequently grown Si interspacing layers to an extent of about 2 nm.     

Synthesis and characterization of styrene/isoprene/ethylene oxide block copolymers

Poly(ethylene oxide/isoprene/styrene/isoprene/ethylene oxide) block copolymers were synthesized using potassium–napthalene catalyst in tetrahydrofuran. The dynamic and thermal properties and water absorption of these tri-block copolymers were determined and related to their bulk morphology.     

Identification and characterization of Podophyllum emodi by API-LC/MS/MS

An API-LC/MS/MS method was developed for the identification of the medicinal herb Podophyllum emodi based on the profile of its aryltetrahydronapthalene and related lignan marker compounds. This was done by matching the structural information from the tandem mass spectrometric data with those lignan marker compounds already reported for the herb. The method could be employed in the absence of reference standards for the markers and was particularly useful in view of the scarcity of supply of these chemical standards. It has been used successfully to differentiate Podophyllum emodi from two commonly used medicinal herbs of a different genus but having similar appearance, Radix clematidis and Radix gentiana, as well as a closely related herb, Podophyllum peltatum.