The Studies on α-Pinene Oxidation over the TS-1. The Influence of the Temperature, Reaction Time, Titanium and Catalyst Content

The work presents the results of studies on α-pinene oxidation over the TS-1 catalysts with different Ti content (in wt%): TS-1_1 (9.92), TS-1_2 (5.42), TS-1_3 (3.39) and TS-1_4 (3.08). No solvent was used in the oxidation studies, and molecular oxygen was used as the oxidizing agent. The effect of titanium content in the TS-1 catalyst, temperature, reaction time and amount of the catalyst in the reaction mixture on the conversion of α-pinene and the selectivities of appropriate products was investigated. It was found that it is most advantageous to carry out the process of α-pinene oxidation in the presence of the TS-1 catalyst with the titanium content of 5.42 wt% (TS-1_2), at the temperature of 85 °C, for 6 h and with the catalyst TS-1 content in the reaction mixture of 1 wt%. Under these conditions the conversion of α-pinene amounted to 34 mol%, and the selectivities of main products of α-pinene oxidation process were: α-pinene oxide (29 mol%), verbenol (15 mol%) and verbenone (12 mol%). In smaller quantities also campholenic aldehyde, trans-pinocarveol, myrtenal, myrtenol, L-carveol, carvone and 1,2-pinanediol were also formed. These products are of great practical importance in food, cosmetics, perfumery and medicine industries. Kinetic studies were also performed for the studied process.

On the extraordinary low quench sensitivity of an AlZnMg alloy

The scope of this work was to investigate the quench sensitivity of a high-purity wrought aluminum alloy Al6Zn0.75 Mg (in this work called 7003pure). This is compared to a similar alloy with the additions of Fe, Si, and Zr at a sum less than 0.3 at.% (in this work called 7003Fe,Si,Zr). Differential scanning calorimetry (DSC) was used for an in situ analysis of quench induced precipitation in a wide range of cooling rates varying between 0.0003 and 3 K/s. In 7003pure, three main precipitation reactions were observed during cooling, a medium temperature reaction with a distinct double peak between 325 and 175 °C and a very low temperature reaction starting at about 100 °C. An additional high temperature reaction related to the precipitation of Mg2Si starting at 425 °C has been observed for 7003Fe,Si,Zr. In terms of hardness after natural as well as artificial aging, alloy 7003pure shows a very low quench sensitivity. Hardness values on the saturation level of about 120 HV1 are seen down to cooling rates of 0.003 K/s. The as-quenched hardness (5 min of natural aging) shows a maximum at a cooling rate of 0.003 K/s, while slower and faster cooling results in a lower hardness. In terms of hardness after aging, 0.003 K/s could be defined as the technological critical cooling rate, which is much higher for 7003Fe,Si,Zr (0.3–1 K/s). The physical critical cooling rates for the suppression of any precipitation during cooling were found to be about 10 K/s for both variants.

Effects of phosphogypsum whiskers modification with calcium stearate and their impacts on properties of bleached softwood paper sheets

By combining the structural properties and characteristics of phosphogypsum whiskers, a preliminary study on the modification of phosphogypsum whiskers and their application in papermaking was carried out. The effects of reaction temperature, reaction time, and reaction concentration on the solubility and retention of modified phosphogypsum whiskers and the effects of phosphogypsum whiskers on the physical properties of paper under different modified conditions were explored. The research results show that, after the phosphogypsum whiskers are modified with calcium stearate, a coating layer will be formed on the surface of the whiskers, which effectively reduces the solubility of the phosphogypsum whiskers. The best modification conditions are: the amount of calcium stearate relative to the absolute dry mass of the phosphogypsum whisker is 2.00%; the modification time is 30 min, and the modification temperature is 60°C. The use of modified phosphogypsum whiskers for paper filling will slightly reduce the whiteness, folding resistance, burst resistance, and tensile strength of the paper, but the tearing degree and retention of the filler will be increased to some extent.

Polyvinyl Butyral Synthesis Process Based on Deep Eutectic Solvent as a Catalyst

Polyvinyl butyral (PVB) was prepared by the condensation reaction of polyvinyl alcohol (PVA) with n-butyraldehyde using a catalyst which is a kind of deep eutectic solvent (DES) made of dodecyltrimethylammonium chloride and p-toluenesulfonic acid. The raw materials and products were characterized by Fourier transform infrared spectroscopy (FT-IR). The effects of the following reaction conditions on the degree of PVB acetal, yield and agglomeration of the products were investigated: the mass ratio of n-butyraldehyde to PVA (mBA/mPVA) of 0.48-0.96, the mass ratio of catalyst to PVA (mcat/mPVA) of 0.16-0.64, the low temperature reaction temperature (5-20℃), and the low temperature reaction time (1-3h). The results showed that at mBA/mPVA =0.8, mcat/mPVA =0.32, low temperature reaction temperature of 15°C and low temperature reaction time of 2 hours, the obtained PVB was a homogeneous powder with the highest acetal degree of 73.85%.

EXPERIMENTATION COLOUR OF GLAZE USING A VARIOUS STONE IN SABAH

Ceramics are the oldest art objects ever produced by humans since prehistoric times. Ceramics are made from clay and will change character when exposed to high temperatures above 1200 degrees celsius. Ceramic product is covered with a layer of glass which is a glaze and has a high resistance to temperature or heat. This research aims to document the production of glaze color systematically using various types of stone in Sabah such as Sungai Moyog stone, Lombong Mamut stone, and stone in Sports Complex, Ranau on the surface of the specimen body produced using by kaolin. In addition, this research also aims to identify the response of experimental samples using a mixture of different percentages using the formula Triaxial Line Blend on the surface of kaolin involving aspects of the material, type of combustion, and decoration techniques. The production of glaze color using natural materials which is a Sungai Moyog stone, Lombong Mamut stone, and Sports Complex stone found around Ranau and Kota Kinabalu, Sabah is an innovation in the production of color sourced from natural materials as well as efforts to develop the ceramic industry in Malaysia. It is more to the production of natural materials that have undergone the production process to produce a new glaze color. Preliminary studies using samples from color agents which are Sungai Moyog stone, Lombong Mamut stone, and Ranau Sports Complex stone were conducted experimentally. The research includes the preparation and formulation of glaze using the material until it successfully produces color pigments according to the temperature reaction and the type of combustion that has been implemented. This research also aims to study the suitability of glaze color on the surface of ceramic products such as kaolin. In conclusion, through this research, we will better understand the processes and ways how to produce glaze color in the ceramic industry by using natural materials found in the environment. Through this research as well, it is possible to identify the minerals present in the experimental materials that influence the reaction in the production of ceramic glaze color.

The intensity of endogenous intoxication syndrome and methods of its therapy for the urinary system infection in children

Endogenous intoxication syndrome is one of the leading syndromes in high urinary system infection activity in children. The study of clinical and laboratory manifestations of endogenous intoxication syndrome with the aim of optimizing its methods of therapy is topical. The examination was conducted in 52 children aged 3–7 years, including 22 children with active forms of pyelonephritis and 30 almost healthy children (control group). Endogenous intoxication syndrome was determined by clinical signs and by the level of leukocyte index of intoxication and medium-sized molecular peptides in blood plasma. Statistical analysis was carried out on the basis of Student’s t-test (p<0.05), the frequency of symptom occurrence (q) in relation to the totality in the group taken for 1 and the coefficients (Q) of the ratio of the comparable indicators in groups. In the control group, the leukocyte intoxication index did not exceed 1.0, the average molecular peptides— 0.24 conditional units. Most patients (q-0.73) had a moderately severe course, expressed symptoms of intoxication, pain abdominal syndrome (q-0.73), dysuria (q-0.73), high temperature (q-0.73). In complex therapy, prebiotic (complex fructoolygosaccharides, inulin and maltodextrin) was prescribed in age dosage for three weeks. Detoxification therapy contributed, first of all, to the positive dynamics of clinical manifestations of the intoxication syndrome. During the first two days, the temperature reaction decreased; on the 4-5th day, the general condition improved, other symptoms of intoxication disappeared; highly reliable (p<0.001) positive changes in the studied indicators were found within 3 weeks. They were characterized by the normalization of the level of leukocyte index of intoxication and medium-sized molecular peptides, which justifies the use of prebiotic products in the complex therapy of urinary system infection in children.

A liquid phase anion-exchange approach to high-quality all-inorganic halide perovskite micro- and nanowires

All-inorganic halide perovskite nanowires (NWs) are promising materials due to they have broad application prospects in the field of optoelectronics, with mixed-halide perovskite nanowires can change the optoelectronic properties by adjusting the halide ratio. Here, we experimentally investigated the two-process governed anion-exchange reaction in single-crystalline CsPbX3 micro- and nanowires. The critical parameters affecting the outcome of the reaction are identified as the reaction temperature, reaction time, and precursor concentrations. Upon examining the photoluminescence and morphology of the NWs, high-quality NWs were obtained by optimizing these critical parameters. The bandgap of the NWs can be tuned over the entire visible spectra (430–700 nm). In addition, photodetectors incorporating single NWs were fabricated, which demonstrated excellent responsivity under illumination. Our results expand the validity of liquid-phase anion exchange to the microscale, and lay the basis for liquid-processed optoelectronics and displays.

Catalytic Dehydration of Fructose to 5-Hydroxymethylfurfural in Aqueous Medium over Nb2O5-Based Catalysts

The catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) in water was performed in the presence of pristine Nb2O5 and composites containing Nb and Ti, Ce or Zr oxides. In all experiments, fructose was converted to HMF using water as the solvent. The catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, N2 physical adsorption, infrared and Raman spectroscopy and temperature-programmed desorption of NH3. Experimental parameters such as fructose initial concentration, volume of the reacting suspension, operation temperature, reaction time and amount of catalyst were tuned in order to optimize the catalytic reaction process. The highest selectivity to HMF was ca. 80% in the presence of 0.5 g·L−1 of bare Nb2O5, Nb2O5-TiO2 or Nb2O5-CeO2 with a maximum fructose conversion of ca. 70%. However, the best compromise between high conversion and high selectivity was reached by using 1 g·L−1 of pristine Nb2O5. Indeed, the best result was obtained in the presence of Nb2O5, with a fructose conversion of 76% and a selectivity to HMF of 75%, corresponding to the highest HMF yield (57%). This result was obtained at a temperature of 165° in an autoclave after three hours of reaction by using 6 mL of 1 M fructose suspension with a catalyst amount equal to 1 g·L−1.

Numerical simulation of n-dodecane spray combustion based on OpenFOAM

For the purpose of providing the scientific insights to combustion characteristics of spray jet, numerical calculations of reacting and non-reacting spray cases are performed for ECN (engine combustion network) Spray A (n-dodecane spray combustion) which coupled finite chemistry combustion model PaSR and detailed chemical reaction kinetics based on OpenFOAM. The applicability and accuracy of the spray model is verified in the non-reacting spray case, and it is found that the predicted spray characteristics such as the penetration length of liquid and vapor and the mixture fraction are in good agreement with the test results. The two processes of low-temperature reaction and high-temperature ignition experienced by n-dodecane spray ignition are analyzed in reacting spray case, and it is found that the low-temperature reaction continues to exothermic before high-temperature ignition, and continues to proceed stably after high-temperature ignition, which promotes high-temperature ignition and flame stability. Finally, the effects of different fuel injection pressures on ignition delay time and flame lift-off length are studied.