Cobalt ferrite nanoparticles prepared by microwave hydrothermal synthesis and adsorption efficiency for organic dyes: Isotherms,thermodynamics and kinetic studies

Magnetic nanoferrites (MFe₂O₄, M = Co, Ni) were successfully synthesised through microwave-hydrothermal route, characterised and used for adsorption of Eriochrome Black T (EBT) and Bromophenol Blue (BRB) dyes from their aqueous solution. The powder XRD patterns confirmed the formation of cubic spinel structure for both the ferrites. Under identical conditions, the adsorption efficiency of CoFe₂O₄ was found relatively higher than the corresponding NiFe₂O_4. Further characterisations revealed that CoFe₂O₄ sample was nearly spherical in size (8–9 nm) with narrow size distribution. The sample showed superparamagnetic behaviour with saturation magnetization (M_s) value (66.4 emu/g). BET surface area calculated for the synthesized cobalt ferrite as 70.9 m²/g. Batch adsorption experiments as a function of initial dye concentration, pH, contact time and adsorbent dose showed the adsorption of dyes depends on pH. Equilibrium adsorption data were well explained by both Langmuir and Freundlich isotherm models. The maximum monolayer adsorption capacities (Q_o) were found to be 82.6 and 25.6 mg/g for EBT and BRB dyes, respectively. Kinetics of the adsorption was best described by pseudo-second-order model. Various thermodynamic parameters such as ΔG, ΔH and ΔS derived from adsorption data over the temperature range 20–50 °C, accounted for a favourable, spontaneous, endothermic physisorption process. The materials showed potential for repeated use without significant decrease in adsorption capacity after proper regeneration.     

织物表面导电线路喷射打印起始端凸起形成过程研究

为提高织物表面微滴喷射打印导电线路的成形质量,针对导电线路喷射打印过程中线路沉积形貌的起始端凸起现象,利用高速相机对线路成形过程进行采集,研究微滴间融合振荡过程中左右接触角的动态变化,微滴与线路融合以及液体向线路起始端的输送过程,提出线路起始端凸起的消除方案并进行实验。结果表明:在融合振荡过程中,微滴向起始端的振荡趋势始终大于向另一侧的振荡趋势,导致打印线路起始端的织物基板润湿区域不断扩大;微滴与线路接触后,其中一部分液体润湿织物基板拓展线路长度,一部分通过线路以恒定速度输送至起始端,在线路起始端形成凸起;利用抗坏血酸溶液润湿织物表面后,成形线路起始端凸起现象得到消除,整体线路路径均匀,沉积形貌良好。     

PAM-粉煤灰体系在煤泥水絮凝沉降过程中的作用及机理

以煤泥水COD、SS、动电位、污泥比阻为切入点,分析了煤泥水的特点及难以絮凝沉降的原因,并研究了PAM-粉煤灰体系在混凝沉降作用中的机理。研究结果表明:PAM-粉煤灰法在最优条件下,清水分离率47%、沉降速度0.357 mm/s;上清液:pH=7.35,SS=55.57 mg/L,COD=37.72 mg/L;污泥比阻为0.062×10^15 m/kg,满足煤泥水循环标准。     

β-环糊精修饰Ni/SFCC强化C9石油树脂催化加氢性能

以废弃的流化催化裂化催化剂（简称SFCC）为载体、β-环糊精为金属络合剂、硝酸镍为镍源，采用湿法浸渍法制备β-环糊精修饰的Ni/SFCC催化剂（简称Ni/SFCC-CD催化剂），考察其对C9石油树脂的催化加氢性能。通过BET比表面积测试、H2程序升温还原、X射线光电子能谱等手段对催化剂的物相结构进行表征，研究β-环糊精的作用机理及其对催化剂加氢性能的影响。研究结果表明：在反应温度为260 ℃、反应压力为7 MPa、反应时间为2.0 h的最优条件下，采用Ni/SFCC-CD催化C9石油树脂加氢，可制得溴值为1.45 gBr/（100 g）、色号（加纳德）小于1的水白色氢化C9石油树脂，催化剂循环使用4次后仍保持良好活性；β-环糊精的作用机理是：β-环糊精与硝酸镍产生络合作用，抑制硝酸镍的分解、控制NiO的结晶过程和增强活性组分Ni与载体之间的相互作用力，从而提高了Ni/SFCC-CD的催化活性和稳定性。     

耦合效应下压力型锚索锚固机理的近似理论分析

为了更加精确地研究压力型锚索的锚固机理,基于锚索预应力与岩土体蠕变的耦合效应推导了锚索预应力方程。在此基础上根据Mindlin问题解,推导了耦合效应作用下锚索砂浆体的压应力和剪应力近似解,并考虑锚索预应力与岩土体蠕变之间的耦合效应进行了案例分析。研究结果表明:锚索预应力和砂浆体受到的应力峰值均按反幂函数随时间逐渐衰减并稳定;承压板的长宽比与压应力峰值之间存在正相关关系,与剪应力峰值之间存在负相关关系;岩土体的泊松比与应力峰值之间存在正相关关系。该成果丰富了压力型锚索锚固机理的理论研究,可为边坡锚固设计提供一定的理论依据。     

Sequence-Dependent Nanofiber Structures of Phenylalanine and Isoleucine Tripeptides

The molecular design of short peptides to achieve a tailor-made functional architecture has attracted attention during the past decade but remains challenging as a result of insufficient understanding of the relationship between peptide sequence and assembled supramolecular structures. We report a hybrid-resolution model to computationally explore the sequence–structure relationship of self-assembly for tripeptides containing only phenylalanine and isoleucine. We found that all these tripeptides have a tendency to assemble into nanofibers composed of laterally associated filaments. Molecular arrangements within the assemblies are diverse and vary depending on the sequences. This structural diversity originates from (1) distinct conformations of peptide building blocks that lead to different surface geometries of the filaments and (2) unique sidechain arrangements at the filament interfaces for each sequence. Many conformations are available for tripeptides in solution, but only an extended β-strand and another resembling a right-handed turn are observed in assemblies. It was found that the sequence dependence of these conformations and the packing of resulting filaments are determined by multiple competing noncovalent forces, with hydrophobic interactions involving Phe being particularly important. The sequence pattern for each type of assembly conformation and packing has been identified. These results highlight the importance of the interplay between conformation, molecular packing, and sequences for determining detailed nanostructures of peptides and provide a detailed insight to support a more precise design of peptide-based nanomaterials.     

Effects of Synthesis Conditions on the Formation of Si-Substituted Alpha Tricalcium Phosphates

Powders of α-TCP containing various amounts of silicon were synthesized by two different methods: Wet chemical precipitation and solid-state synthesis. The obtained powders were then physico–chemically studied using different methods: Scanning and transmission electron microscopy (TEM and SEM), energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffractometry (PXRD), infrared and Raman spectroscopies (FT-IR and R), and solid-state nuclear magnetic resonance (ssNMR). The study showed that the method of synthesis affects the morphology of the obtained particles, the homogeneity of crystalline phase and the efficiency of Si substitution. Solid-state synthesis leads to particles with a low tendency to agglomerate compared to the precipitation method. However, the powders obtained by the solid-state method are less homogeneous and contain a significant amount of other crystalline phase, silicocarnotite (up to 7.33%). Moreover, the microcrystals from this method are more disordered. This might be caused by more efficient substitution of silicate ions: The silicon content of the samples obtained by the solid-state method is almost equal to the nominal values.     

Extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins: part I – Effect of moisture content

This study investigated the effects of moisture content (MC) on the physicochemical properties of extruded meat alternatives made from Maillard-reacted beef bone hydrolysate and plant proteins. Samples were extruded at 170 °C (maximum barrel temperature), at 3.6 kg h⁻¹ (liquid feed rate) and at 1.8, 2.2, 2.6 and 3.0 kg h⁻¹ (dry feed rates) to obtain MC of 60%MC, 56%MC, 52%MC and 49%MC, respectively. Meat alternatives at 52%MC showed the greatest degree of texturisation. However, meat alternatives at 49%MC were the closest in terms of both textural and microstructural properties to reference sample, boiled chicken breast. Results from protein solubility suggested that a large amount of aggregated proteins were associated with hydrogen bonds, while disulphide bonds were the main contributor in the formation of fibrous structure in meat alternatives. Results showed that the change in MC as process parameter played an important role in the formation of fibrous structure in extruded meat alternatives.     

The effect of traffic data source on deterioration rates of heavy-duty flexible pavements

The purpose of this study is to assess the effect of traffic data source (estimated vs. actual) on predicted progression rates of roughness and rutting for heavy-duty flexible pavements of rural freeways. Progression rates are predicted using calibrated HDM-4 models. The assessment is performed in terms of variations in maintenance intervention timing associated with the variations in progression rates. Time series pavement condition data (covering 3–5 years) have been collected for 7 sections of rural freeways for use in calibrating HDM-4 deterioration models. They range in length from 10 to 60.8 km and cover different traffic volumes, climate zones and subgrade soil types. For these sections, estimated annual average daily traffic (AADT), growth factors and assumed loading have been extracted from relevant database. Only six segments of these sections have Weigh-in-Motion (WIM) sites so relevant actual AADT, growth factors and axle load distributions have been extracted from WIM reports. The results of running the calibrated HDM-4 deterioration models using different traffic data show that actual traffic data from WIM sites result in higher rates of deterioration to that of estimated data for four sites, resulting in earlier intervention timing and higher present value agency cost. The other two sites have lower rates with actual data due to lower traffic loading than estimated.