Effect of synthesis methods for mesoporous zirconia on its structural and textural properties

Zirconia was synthesized by sol–gel and post-hydrothermal treatment under autogenous pressure in order to study the effect of synthesis methods on its structural and textural properties. On the basis of thermal analysis, in situ X-ray diffraction and Raman spectroscopy techniques, the synthesis processes exhibit similar thermal behavior and zirconia phase transformation. The effect of in situ calcination temperature on the crystallization behavior, crystal phase transition, and crystallite size analysis was studied. The results obtained revealed that amorphous zirconia transformed into tetragonal phase above 400 °C and thermally stabilized up to 700 °C. A biphasic mixture of tetragonal and monoclinic zirconia was formed at 750 °C. Activation energy of sintering due to grain growth mechanism predicted that the zirconia phase transformation is due to the increase in the crystallite size of tetragonal phase above its critical size. The post-hydrothermal treatment resulted in the formation of high surface area mesoporous zirconia (213 m² g^?1). Upon increasing the calcination temperature, a pronounced decrease in the specific surface area of zirconia samples due to sintering process and phase transformation.     

重新认识物理化学的地位和教学改革的必要性

针对物理化学被削弱的现状,本文着重从理论高度和具体实践阐明该学科在经济振兴、科技腾飞、造才育帅中的战略地位,并以实践能力和创新精神的培养为目标,论述了该课程在化学教学中的重要地位,存在的问题,进行教学改革的必要性.     

New Frontiers in Monoclonal Antibodies for the Targeted Therapy of Acute Myeloid Leukemia and Myelodysplastic Syndromes

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) represent an unmet clinical need whose prognosis is still dismal. Alterations of immune response play a prominent role in AML/MDS pathogenesis, revealing novel options for immunotherapy. Among immune system regulators, CD47, immune checkpoints, and toll-like receptor 2 (TLR2) are major targets. Magrolimab antagonizes CD47, which is overexpressed by AML and MDS cells, thus inducing macrophage phagocytosis with clinical activity in AML/MDS. Sabatolimab, an inhibitor of T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3), which disrupts its binding to galectin-9, has shown promising results in AML/MDS, enhancing the effector functions of lymphocytes and triggering tumor cell death. Several other surface molecules, namely CD33, CD123, CD45, and CD70, can be targeted with monoclonal antibodies (mAbs) that exert different mechanisms of action and include naked and conjugated antibodies, bispecific T-cell engagers, trispecific killer engagers, and fusion proteins linked to toxins. These novel mAbs are currently under investigation for use as monotherapy or in combination with hypomethylating agents, BCL2 inhibitors, and chemotherapy in various clinical trials at different phases of development. Here, we review the main molecular targets and modes of action of novel mAb-based immunotherapies, which can represent the future of AML and higher risk MDS treatment.     

哒嗪与联苯胺的新型共轭共聚物的合成及其表征

报道了联苯二胺在二价镍配合物存在下直接与3,6-二氯哒嗪的格氏(Grignard)试剂共聚合成了联苯二胺与哒嗪共聚物,新合成方法所得的共聚物通过红外光谱(FT IR),核磁共振谱(1H NMR)等进行了表征。该合成方法所得聚合物收率为60%。该类聚合物的紫外-可见吸收光谱中在313 nm处观察到最大吸收峰。根据聚合物的粉末X-射线衍射谱(XRD),热重分析(TG)对所得聚合物的结晶性和热稳定性进行了分析。     

Floating ring journal bearings: theory, design and optimization

The performance characteristics and design data for journal bearings with a precise floating ring inserted between the rotating journal and a rigid housing are investigated theoretically. Based on convenient boundary conditions, a theory has been developed to predict the floating ring behaviour. Performance charts are presented with curves provided with optimum design areas to help in practical design applications. Induced ring speed, hydrodynamic behaviour, oil film variation, load capacity and frictional drag could thus be analytically or graphically determined. Results indicate that the ring dimensions are a dominant factor in deciding the final bearing behaviour and that the oil film thickness between the ring and the housing is much thinner than that between the journal and the ring. The floating ring bearing showed less frictional power loss than a fixed sleeve bearing, but this may have been achieved at the expense of the load capacity.     

Structural,magnetic and electrical properties of Ga-substituted NiCuZn nanocrystalline ferrite

In this work, we studied the substitution effect of iron by gallium on the structural, magnetic and electrical properties of the ferrite system; Ni_0.5Cu_0.25Zn_0.25Fe_2−xGa_xO₄ (x = 0–1.0), synthesized by using the urea combustion method. XRD patterns of the samples calcined at 700 °C show only cubic spinel ferrite with an average crystallite sizes in the range of 40–54 nm. The lattice parameters were slightly changed with increasing Ga content which can be explained on the basis of the relative ionic radii of Ga³⁺ and Fe³⁺ ions. FT-IR measurements show two fundamental absorption bands, assigned to the vibration of tetrahedral and octahedral complexes, which were slightly changed with increasing Ga content. Mössbauer measurements enable us to predict the possible cation distribution of the system. It was found that Ga³⁺ ion prefer to substitute Fe³⁺ ions located in the octahedral site. Superparamagnetic state was observed in the Mössbauer spectra of the samples with Ga content >0.5. The decrease of the magnetic hyperfine field with gallium concentration was explained on the basis of supertransferred hyperfine interaction. A semiconducting behavior was inferred for all samples and the conductivity values were found to decrease with increasing the Ga content. The conduction mechanism in the spinel ferrite compounds was explained in terms of the hopping conduction process. The dielectric constant measured as a function of frequency and temperature was found to be dependent on the Ga concentration. The determined transition temperature was found to decrease with increasing Ga content.     

Fatty acids,volatiles, sterols and triterpenic alcohols of six monovarietal Tunisian virgin olive oils

Fatty acids, volatiles, sterols, aliphatic and triterpenic alcohols of six monovarietal Tunisian virgin olive oils were analyzed. The results suggested that the compositional data concerning the above analytical fractions were effective in discriminating between varieties. The oils were found to contain high levels of oleic acid (up to 71.70% in the Oueslati variety). β‐Sitosterol (up to 85.46% in the Jdallou variety) and Δ5‐avenasterol (up to 30.97% in the El Hor variety) were the principal sterols in all samples; campesterol and stigmasterol were found at low levels. (E)‐2‐Hexenal was the main compound that characterizes the olive oil headspace of all samples. The other compounds identified were mainly C₆ aliphatic components.     

Equilibrium and kinetic studies of the cationic dye removal capability of a novel biosorbent Tamarindus indica from textile wastewater

In this paper, the use of tamarind hull biosorbent (Tamarindus indica) has been investigated to remove cationic dyes from textile eflluent. Basic Violet 6 and Basic Red 18 were used as cationic dye models. The surface characteristics of tamarind hull were investigated using Fourier Transform–infrared and scanning electron microscopy. The influence of process variables such as adsorbent dosage, initial dye concentration and pH were studied. The presence of fuctional groups such as hydroxy and amine groups onto the tamarind hull surface were proved by Fourier Transform–infrared analysis. Data were evaluated for compliance with the Langmuir and Freundlich isotherm models. The results indicated that the data for adsorption of Basic Violet 6 and Basic Red 18 onto tamarind hull fitted well with the Freundlich isotherm model. Also, the adsorption kinetics of Basic Violet 6 and Basic Red 18 on biosorbent was studied. The rates of sorption were found to conform to pseudo‐second‐order kinetics with good correlation. Results indicated that tamarind hull could be used as a biosorbent to remove cationic organics from contaminated watercourses.     

A model for improved solar irradiation measurement at low flux

Accurate measurement of solar radiation heat flux is important in characterizing the performance of CSP plants. Thermopile type Heat Flux Sensors (HFSs) are usually used for this purpose. These sensors are typically reasonably accurate at high heat fluxes. However measurement accuracy drops significantly as the measured radiation is below 1 kW/m², this often leads to underestimation of the actual flux. At the Masdar Institute Beam Down Solar Thermal Concentrator (BDSTC), measurement of fluxes ranging from 0 kW/m² to more than 100 kW/m² is required. To improve the accuracy of the sensors in the lower range around 1 kW/m², we have performed a test under ambient (not-concentrated) sunlight. Such low irradiation levels are experienced in characterizing the concentration quality of individual heliostats. It was found during the test that the measurement at this low range is significantly affected by ambient conditions and transients in the HFS cooling water temperature. A Root Mean Square Error (RMSE) of more than 100 W/m² was observed even though we kept the transients in water temperature to a minimum. Hence we devised a model to account for this measurement error at this flux range. Using the proposed model decreased the RMSE to less than 10 W/m². The application of the model on existing heat flux measurement installations is facilitated by the fact that it only employs easily measurable variables. This model was checked by using a test data set and the results were in good agreement with the training data set.     

Volatile compounds characterising Tunisian virgin olive oils: the influence of cultivar

In this work, the volatile profiles of four Tunisian virgin olive oils were established by headspace‐solid phase microextraction and gas chromatography, using flame ionisation and mass spectrometer detectors. More than eighty compounds were isolated and characterised, representing 97–99% of the total GC area. The main volatile compounds present in the oil samples were determined quantitatively, the major constituents were often aldehydes, particularly (E)‐2‐hexenal (48–90%). Significant differences in the content of volatile constituents were observed. These quantitative differences were used to distinguish between virgin olive oils from different varieties.