Study of TATP: Influence of Reaction Conditions on Product Composition

The influence of reaction conditions (temperature, catalyst type, catalyst concentration – represented as molar ratio catalyst/acetone n_c/n_a) on the composition of the product formed from the reaction of acetone and hydrogen peroxide (30%) under acid catalysis was studied. 3,3,6,6,9,9‐Hexamethyl‐1,2,4,5,7,8‐hexoxonane (TATP) was found to be the major product when the content of the catalyst in the reaction mixture is low (n_c/n_a ≤ 0.5). A single side product (peak 10.2) in an amount ranging from 1.5 to 8% of the total peak area was present in all the prepared samples. Three other side products were found when catalyzing by hydrochloric and nitric acids. Temperature and catalyst type did not have a significant influence on the composition of the product at low catalyst concentration. Increasing the catalyst concentration led to the formation of 3,3,6,6‐tetramethyl‐1,2,4,5‐tetroxane (DADP) either as a co‐product of TATP or as an exclusive product depending on the concentration of the catalyst.     

Two-Dimensional Modeling of Self-Propagating High-Temperature Synthesis of Strontium-Doped Lanthanum Manganate

A two-dimensional finite element model is developed to study the reaction kinetics and heat transfer during the self-propagating high-temperature synthesis of La_0.6Sr_0.4MnO₃, a cathode and interconnect material used in solid oxide fuel cells. The activation energy of La_0.6Sr_0.4MnO₃ formation was calculated from experimental temperature history. The calculated spatial-temporal temperature profile, heat generation rate, reaction conversion, and flow pattern of surrounding gas during the reaction are reported in this work. Hot spots are found at the corner near the ignition point shortly after the ignition. The model provided a simple and reliable way to design a large-scale production of La_0.6Sr_0.4MnO₃.     

Colorimetric method for phase evaluation

Measurements of very small phase changes in optical measurement techniques are usually performed with interferometric methods that are based on evaluation of interference patterns, which correspond to a phase change of the investigated wave field. If values of the phase change are small, it is difficult to determine accurately the phase values, and one needs very expensive measurement systems. We present a simple method for evaluation of small phase variations that uses the interference of polychromatic light. The phase change affects the color of the interference pattern, and the color of the interference pattern corresponds to a specific phase change that can be evaluated using colorimetric analysis. We describe and analyze our colorimetric phase evaluation method. The proposed method offers accurate results, and it may be suitable for practical utilization in the optical industry.     

Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry

Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature T(g). We apply ultrafast DSC to the phase-change material Ge(2)Sb(2)Te(5) (GST) and show that if the range of heating rates is extended to more than 10(4) K s(-1), the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near T(g) there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems.     

Merging high doxorubicin loading with pronounced magnetic response and bio-repellent properties in hybrid drug nanocarriers

Hybrid magnetic drug nanocarriers are prepared via a self-assembly process of poly(methacrylic acid)-graft-poly(ethyleneglycol methacrylate) (p(MAA-g-EGMA)) on growing iron oxide nanocrystallites. The nanocarriers successfully merge together bio-repellent properties, pronounced magnetic response, and high loading capacity for the potent anticancer drug doxorubicin (adriamicin), in a manner not observed before in such hybrid colloids. High magnetic responses are accomplished by engineering the size of the magnetic nanocrystallites (～13.5 nm) following an aqueous single-ferrous precursor route, and through adjustment of the number of cores in each colloidal assembly. Complementing conventional magnetometry, the magnetic response of the nanocarriers is evaluated by magnetophoretic experiments providing insight into their internal organization and on their response to magnetic manipulation. The structural organization of the graft-copolymer, locked on the surface of the nanocrystallites, is further probed by small-angle neutron scattering on single-core colloids. Analysis showed that the MAA segments selectively populate the area around the magnetic nanocrystallites, while the poly(ethylene glycol)-grafted chains are arranged as protrusions, pointing towards the aqueous environment. These nanocarriers are screened at various pHs and in highly salted media by light scattering and electrokinetic measurements. According to the results, their stability is dramatically enhanced, as compared to uncoated nanocrystallites, owing to the presence of the external protective PEG canopy. The nanocarriers are also endowed with bio-repellent properties, as evidenced by stability assays using human blood plasma as the medium.     

Dependence of Strehl ratio on f-number of optical system

Formulas for a minimum of wave aberration variance and a maximum of the Strehl ratio in the optimal image point are derived using the third- and fifth-order aberration theory. Moreover, relations for the calculation of the optimal value of f-number of the optical system were derived, which enabled us to theoretically analyze real optical systems and their image quality. The optimal f-number corresponds to such a value of f-number when the image quality of a real optical system is comparable to an aberration-free optical system. This value may also serve as an auxiliary criterion of the image quality of the optical system, for example, in photography.     

Investigation of Protein Composition of Barley by Gel Electrophoresis and MALDI Mass Spectrometry with Regard to the Malting and Brewing Process

The protein composition of barley partly determines its quality in terms of malting and brewing. For this reason, the water‐soluble proteins of two different barley cultivars were investigated by gel electrophoresis and matrix‐assisted laser desorption/ionization mass spectrometry. Mass spectra were obtained directly from barley extracts by using three matrices. According to the quality of the measured spectra, it was possible to establish which matrix was the most suitable for the analysis of water‐soluble proteins from barley. We found that the protein patterns did not differ significantly between Jersey and Tolar varieties. However, our results showed the influence of the malting process on the posttranslational modification of some water‐soluble barley proteins. These proteins also survive the brewing process and they are very important for the formation and stability of beer foam. Several barley proteins were also identified by proteomic analysis.     

制鞋工业中用于抑菌处理的甘油一酸酯(续)

3 RESULTS AND DISCUSSION 3.1 Testing the MAG antimycotic effectivity by micro titration method This method was used only for the yeasts Candida albicans and Candida parapsilosis.     

Thermal Conductivity Measurement of Bulk Solids

The coefficient of thermal conductivity of particulates and powders is of great importance in process engineering. The prediction of thermal properties of powders using empirical equations is still difficult due to the wide range of specific attributes. This article describes a new measurement methodology for a laboratory device that can be used to determine the thermal conductivity of bulk solids. The presented results show that the created device is highly applicable in industrial practice. It is possible to examine the coefficient of thermal conductivity depending on the sample temperature, the granulometry results and the morphological composition, the moisture content, the degree of consolidation, and other variables that may enter into the entire process and affect it significantly.