Alkyl dimethyl betaine activates the low-temperature collection capacity of sodium oleate for scheelite

The impact of alkyl dimethyl betaine (ADB) on the collection capacity of sodium oleate (NaOl) at low temperatures was evaluated using flotation tests at various scales. The low-temperature synergistic mechanism of ADB and NaOl was explored by infrared spectroscopy, X-ray photoelectron spectroscopy, surface tension measurement, foam performance test, and flotation reagent size measurement.The flotation tests revealed that the collector mixed with octadecyl dimethyl betaine (ODB) and NaOl in a mass ratio of 4:96 exhibited the highest collection capacity. The combined collector could increase the scheelite recovery by 3.48% at low temperatures of 8–12℃. This is particularly relevant in the Luanchuan area, which has the largest scheelite concentrate output in China. The results confirmed that ODB enhanced the collection capability of NaOl by improving the dispersion and foaming performance. Betaine can be introduced as an additive to NaOl to improve the recovery of scheelite at low temperatures.

电化学法合成聚苯胺及其防腐蚀应用——“聚苯胺化学合成”实验的改进与创新设计

聚苯胺作为最受关注的导电高分子材料之一,在诸多领域均有广泛应用。聚苯胺的化学合成实验是材料化学及相关专业实验教学中的代表性实验,然而,该实验存在诸多不足,如产物性质对溶剂的选择、掺杂剂类型、反应时间、温度等条件高度敏感,表征手段单一,产率不稳定且重现性差等。本实验是对“聚苯胺化学合成”实验的改进,将原实验中化学合成法更改为电化学合成法,同时结合了仪器分析实验“循环伏安分析法”和开放性实验“防腐涂料的制备”等相关课程实验,巧妙地将其从一个验证性制备实验改进为一个集制备条件自主选择及防腐性质测试为一体的创新设计实验,使学生连贯地学习聚苯胺的合成、掺杂及相关的电化学知识,对导电高分子的广泛应用有更清晰的认识。本改进实验内容丰富,更贴合现代化学及材料学科发展,有助于学生将多门课程中的理论知识融会贯通,提升综合技能。

Tailoring Iron-Ion Release of Cellulose-Based Aerogel-Coated Iron Foam for Long-Term High-Power Microbial Fuel Cells

The presence of iron(Fe) has been found to favor power generation in microbial fuel cells(MFCs). To achieve long-term power production in MFCs, it is crucial to effectively tailor the release of Fe ions over extended operating periods. In this study, we developed a composite anode(A/IF) by coating iron foam with cellulose-based aerogel. The concentration of Fe ions in the anode solution of A/IF anode reaches 0.280 μg/mL(Fe^(2+) vs. Fe^(3+) = 61%:39%) after 720 h of aseptic primary cell operation. This value was significantly higher than that(0.198 μg/mL, Fe^(2+) vs. Fe^(3+) = 92%:8%) on uncoated iron foam(IF), indicating a continuous release of Fe ions over long-term operation. Notably, the resulting MFCs hybrid cell exhibited a 23% reduction in Fe ion concentration(compared to a 47% reduction for the IF anode) during the sixth testing cycle(600-720 h). It achieved a high-power density of 301 ± 55 mW/m^(2) at 720 h, which was 2.62 times higher than that of the IF anode during the same period. Furthermore, a sedimentary microbial fuel cell(SMFCs) was constructed in a marine environment, and the A/IF anode demonstrated a power density of 103 ± 3 mW/m^(2) at 3240 h, representing a 75% improvement over the IF anode. These findings elucidate the significant enhancement in long-term power production performance of MFCs achieved through effective tailoring of Fe ions release during operation.

Self-Assembly of Bacteria in Alternating-Current Electric Fields

Self-assembly of bacteria in electric fields is a promising route to fabricate biomaterials with reversible and specific structures.However,due to relatively less studies,our understanding of the self-assembly of bacteria in electric fields is still incomplete.Particularly,how different bacterial species behave differently in their fieldmediated self-assembly behavior remains to be disclosed.In this study,we choose four bacterial species,including Shewanella oneidensis,Pseudomonas aeruginosa,Bacillus subtilis and Lactococcus lactis as model systems,and investigate their self-assembly behavior in alternating-current(AC)electric fields for both diluted and concentrated suspensions.The phase diagrams in the plane of applied field strength vs frequency are obtained.The results show that in diluted suspensions,a transition sequence of isotropic–paranematic–string–columnar phases is observed in all strains as the field strength increases.Details of the assembled structures are quantitatively differentiated among different strains.In concentrated suspensions,besides the isotropic and paranematic phases,a higher ordered phase with interdigitating rectangular crystal domains(OIR)and an ordered phase with smectic A liquid crystal domains are observed for S.oneidensis and P.aeruginosa,respectively.Our findings shed new light on fabricating potential biomaterials by assembling cells of appropriately chosen bacterial species that have desired surface properties under AC electric fields.

Investigation and Analysis of Main Diseases of Landscape Plants in the Main Urban Area of Lu'an City

To figure out the disease occurrence of landscape plants in the main urban area of Lu'an City,the author investigated the disease occurrence of landscape plants in park green space,residential green space,unit attached green space and main road in the area under administration.The survey results showed that there were 29 species of urban landscape plant diseases,mainly powdery mildew and spot diseases.According to the characteristics of the diseases,the causes and problems of the diseases were analyzed,and the corresponding prevention and control measures were put forward.

基于DIC技术的高温后混凝土变形性能

基于DIC(数字图像相关)技术,对经历20,200,400,600和800℃后的混凝土在单轴受压过程中的全场位移进行采集,分析了混凝土在不同温度下、不同受力阶段应变云图的变化特征和变形参数的变化规律.结果表明:400℃是混凝土横向应变集中区域与纵向应变压缩量最大区域匹配的临界温度;横向应力应变曲线原点至上升段0.4fcθ(fcθ为温度θ下的峰值应力)时对应的斜率Gr-H对温度的响应要比弹性模量Eθ对温度的响应更加敏感;高温损伤会导致混凝土在较低应力比下产生较大的体积压缩.

DIC技术分析玄武岩纤维混凝土单轴受压应力应变曲线研究

基于DIC技术对玄武岩纤维混凝土在单轴受压过程中的全场位移和应变进行采集,分析混凝土在不同纤维掺量、不同受力阶段下应变云图的变化特征和变形参数的变化规律,并拟合出玄武岩纤维混凝土单轴受压的应力应变曲线。结果表明:掺入玄武岩纤维可减小混凝土的变形,0.2%纤维掺量的混凝土整体变形性能更好。不同玄武岩纤维掺量混凝土的应力-应变曲线上升段几乎重合,下降段表现出不同的变形性能。掺入纤维可以降低峰值应变到极限应变下降斜率,掺入0.2%玄武岩纤维更有利于提高本试验条件下混凝土的延性性能。

压力与温度对炭黑填充丁苯橡胶复合材料动静态性质影响的分子模拟

采用分子动力学模拟研究了不同压力与温度对炭黑填充丁苯橡胶复合体系动静态性能的影响。结果表明,复合体系的玻璃化转变温度随着压力升高呈现线性上升;体系自由体积与分子链尺寸随着压力上升或温度下降而减小,这也导致了分子链平动扩散与旋转动力学的降低。通过计算材料储能模量、损耗模量与损耗因子,发现材料储能模量与损耗模量随着压力上升或温度下降而上升,而材料损耗因子随着压力上升或温度下降而逐渐减小。这些结果为理解水声材料在大压力宽温域环境下的性能演变提供了微观机理。

Biosynthesis of poly-3-hydroxybutyrate with a high molecular weight by methanotroph from methane and methanol

Poly-3-hydroxybutyrate （PHB） can be produced by various species of bacteria. Among the possible carbon sources, both methane and methanol could be a suitable substrate for the production of PHB. Methane is cheap and plentiful not only as natural gas, but also as biogas. Methanol can also maintain methanotrophic activity in some conditions. The methanotrophic strain Methylosinus trichosporium IMV3011 can accumulate PHB with methane and methanol in a brief nonsterile process. Liquid methanol （0.1%） was added to improve the oxidization of methane. The studies were carried out using shake flasks. Cultivation was performed in two stages： a continuous growth phase and a PHB accumulation phase under the conditions short of essential nutrients （ammonium, nitrate, phosphorus, copper, iron （Ⅲ）, magnesium or ethylenediamine tetraacetate （EDTA）） in batch culture. It was found that the most suitable growth time for the cell is 144 h. Then an optimized culture condition for second stage was determined, in which the PHB concentration could be much increased to 0.6 g/L. In order to increase PHB content, citric acid was added as an inhibitor of tricarboxylic acid cycle （TCA）. It was found that citric acid is favorable for the PHB accumulation, and the PHB yield was increased to 40% （w/w） from the initial yield of 12% （w/w） after nutrient deficiency cultivation. The PHB produced is of very high quality with molecular weight up to 1.5 × 10^6Da.

Utilization of wastewater from zeolite production in synthesis of flotation reagents

The application of waste alkali liquids as a substitute of sodium hydroxide for the saponification to improve the collection performance of fatty acids was investigated by saponification reaction test and flotation test.The results of the saponification reaction test indicated that the optimal conditions for the saponification were stirring rate of 55 r/min,initial temperature of 40℃ and stirring time of 45 min.Meanwhile,the laboratory scale and industrial scale flotation experiments showed that the fatty acid salt synthesized by wastewater achieved an index comparable to fatty acid sodium synthesized by sodium hydroxide.As a consequence,it was feasible to replace sodium hydroxide with the wastewater from zeolite production for fatty acid saponification.The cross-border utilization of waste alkali liquids not only reduced environmental pollution,but also produced excellent economic benefits.

Abiotic-Biological Hybrid Systems for CO2 Conversion to Value-Added Chemicals and Fuels

Abiotic-biological hybrid systems that combine the advantages of abiotic catalysis and biotransformation for the conversion of carbon dioxide(CO2)to value-added chemicals and fuels have emerged as an appealing way to address the global energy and environmental crisis caused by increased CO2 emission.We illustrate the recent progress in this field.Here,we first review the natural CO2 fixation pathways for an in-depth understanding of the biological CO2 transformation strategy and why a sustainable feed of reducing power is important.Second,we review the recent progress in the construction of abiotic-biological hybrid systems for CO2 transformation from two aspects:(i)microbial electrosynthesis systems that utilize electricity to support whole-cell biological CO2 conversion to products of interest and(ii)photosynthetic semiconductor biohybrid systems that integrate semiconductor nanomaterials with CO2-fixing microorganisms to harness solar energy for biological CO2 transformation.Lastly,we discuss potential approaches for further improvement of abiotic-biological hybrid systems.

High T_(c) Superconductivity in Heavy Rare Earth Hydrides

Sulfur and lanthanum hydrides under compression display superconducting states with high observed critical temperatures.It has been recently demonstrated that carbonaceous sulfur hydride displays room temperature superconductivity.However,this phenomenon has been observed only at very high pressure.Here,we theoretically search for superconductors with very high critical temperatures,but at much lower pressures.We describe two of such sodalite-type clathrate hydrides,YbH6 and LuH6.These hydrides are metastable and are predicted to superconduct with T_(c)~145 K at 70 GPa and T_(c)~273 K at 100 GPa,respectively.This striking result is a consequence of the strong interrelationship between the f states present at the Fermi level,structural stability,and the final T_(c) value.For example,TmH6,with unfilled 4f orbitals,is stable at 50 GPa,but has a relatively low value of T_(c) of 25 K.The YbH6 and LuH6 compounds,with their filled f-shells,exhibit prominent phonon"softening",which leads to a strong electron-phonon coupling,and as a result,an increase in T_(c).

Bioengineered materials with selective antimicrobial toxicity in biomedicine

Fungi and bacteria afflict humans with innumerous pathogen-related infections and ailments.Most of the commonly employed microbicidal agents target commensal and pathogenic microorganisms without discrimination.To distinguish and fight the pathogenic species out of the microflora,novel antimicrobials have been developed that selectively target specific bacteria and fungi.The cell wall features and antimicrobial mechanisms that these microorganisms involved in are highlighted in the present review.This is followed by reviewing the design of antimicrobials that selectively combat a specific community of microbes including Gram-positive and Gram-negative bacterial strains as well as fungi.Finally,recent advances in the antimicrobial immunomodulation strategy that enables treating microorganism infections with high specificity are reviewed.These basic tenets will enable the avid reader to design novel approaches and compounds for antibacterial and antifungal applications.

Direct detection of a single[4Fe-4S]cluster in a tungsten-containing enzyme:Electrochemical conversion of CO_(2) into formate by formate dehydrogenase

The conversion of CO_(2) into fuels and valuable chemicals is one of the central topics to combat climate change and meet the growing demand for renewable energy.Herein,we show that the formate dehydrogenase from Clostridium ljungdahlii(ClFDH)adsorbed on electrodes displays clear characteristic voltammetric signals that can be assigned to the reduction and oxidation potential of the[4Fe-4S]^(2+/+)cluster under nonturnover conditions.Upon adding substrates,the signals transform into a specific redox center that engages in catalytic electron transport.ClFDH catalyzes rapid and efficient reversible interconversion between CO_(2) and formate in the presence of substrates.The turnover frequency of electrochemical CO_(2) reduction is determined as 1210 s^(-1) at 25℃ and pH 7.0,which can be further enhanced up to 1786 s^(-1) at 50℃.The Faradaic efficiency at−0.6 V(vs.standard hydrogen electrode)is recorded as 99.3%in a 2-h reaction.Inhibition experiments and theoretical modeling disclose interesting pathways for CO_(2) entry,formate exit,and OCN−competition,suggesting an oxidation-state-dependent binding mechanism of catalysis.Our results provide a different perspective for understanding the catalytic mechanism of FDH and original insights into the design of synthetic catalysts.

TEPS用EPS基板工艺参数与性能关系试验研究

为了研究工艺参数对可发性聚苯乙烯(expandable polystyrene,EPS)基板热学力学性能的影响,以蒸汽压力和一次发泡堆积密度作为工艺控制参数,通过导热系数、压缩强度试验和扫描电子显微镜(scanning electron microscope,SEM)分析研究EPS基板的热学力学性能及形成机理。结果表明:蒸汽压力上升,导热系数先降后升,压缩强度降低,蒸汽压力为0.08 MPa时,导热系数最低为0.0426 W/(m·K);一次发泡堆积密度增大,导热系数先降后升,压缩强度先升后降,一次发泡堆积密度为14.94 kg/m^(3)时,压缩强度最大为79 kPa。一次发泡堆积密度相同时,孔径增大,导热系数升高,升幅为3.05%;孔径相同时,孔分布越窄、越合理,导热系数越低。壁厚越薄,压缩强度越小,降幅为17.72%。

美育在大学生思想政治素质教育中的应用

分析美育对于提高大学生思想政治素质的价值:助力于大学生思想素质、政治素质、道德素质的提升。指出美育在大学生思想政治素质教育中的缺失:美育被作为美学专业,大学生审美能力缺失,大学生思想政治素质教育缺乏美育融入。提出把美育贯穿于思想政治教育全过程,提高思政课教师的美育素养和能力,提高大学生的美育素养和能力,营造良好的校园美育环境。

Three-Dimensional N-Doped Carbon Nanotube/Graphene Composite Aerogel Anode to Develop High-Power Microbial Fuel Cell

Optimizing the structure of electrode materials is one of the most effective strategies for designing high-power microbial fuel cells(MFCs).However,electrode materials currently suffer from a series of shortcomings that limit the output of MFCs,such as high intrinsic resistance,poor electrolyte wettability,and low microbial load capacity.Here,a three-dimensional(3D)nitrogen-doped multiwalled carbon nanotube/graphene(N-MWCNT/GA)composite aerogel is synthesized as the anode for MFCs.Comparing nitrogen-doped GA,MWCNT/GA,and N-MWCNT/GA,the macroporous hydrophilic N-MWCNT/GA electrode with an average pore size of 4.24μm enables high-density loading of the microbes and facilitates extracellular electron transfer with low intrinsic resistance.Consequently,the hydrophilic surface of N-MWCNT can generate high charge mobility,enabling a high-power output performance of the MFC.In consequence,the MFC system based on N-MWCNT/GA anode exhibits a peak power density and output voltage of 2977.8 mW m^(−2)and 0.654 V,which are 1.83 times and 16.3%higher than those obtained with MWCNT/GA,respectively.These results demonstrate that 3D N-MWCNT/GA anodes can be developed for high-power MFCs in different environments by optimizing their chemical and microstructures.

Thiophene-Conjugated Porous C_(3)N_(4) Nanosheets for Boosted Photocatalytic Nicotinamide Cofactor Regeneration to Facilitate Solar-to-Chemical Enzymatic Reactions

The low catalytic efficiency of redox-active cofactor photoregeneration severely limits the performance of photoenzymatic hybrid systems. Herein, we synthesized thiophene-conjugated porous C3N4 nanosheets(CN-ATCN) exhibiting boosted photoregeneration activity of nicotinamide cofactors(NADH and NADPH), which are the most common redox cofactors of oxidoreductases, with regeneration rates of 59.00 μM/min for NADH and 40.99 μM/min for NADPH, ~ 84.3 and 24.7 times higher than those of bulk g-C3N4, respectively. The thin nanosheet structure of CN-ATCN facilitates the exposure of active sites to reactants and favors the diff usion of reactants and products. Upon conjugation of a thiophene moiety into the carbon nitride framework, the optical and photoelectric properties of CN-ATCN were considerably enhanced by an extended π-conjugation system in the frameworks and molecular type II heterojunctions formed between the incorporated and nonincorporated portions of CN-ATCN. Upon coupling NAD(P)H photoregeneration reaction by CN-ATCN with NAD(P)H-dependent enzymatic systems, sustainable synthesis of L-tert-leucine and styrene oxide was achieved with rates of 964 and 14.9 μM/h, respectively.

First-principles study on the conventional superconductivity of N-doped fcc-LuH_(3)

Recently,room-temperature superconductivity has been reported in a nitrogen-doped lutetium hydride at near-ambient pressure[Dasenbrock-Gammon et al.,Nature 615,244(2023)].The superconducting properties might arise from Fm3m-LuH_(3)−δNε.Here,we systematically study the phase diagram of Lu–N–H at 1 GPa using first-principles calculations,and we do not find any thermodynamically stable ternary compounds.In addition,we calculate the dynamic stability and superconducting properties of N-doped Fm3m-LuH_(3) using the virtual crystal approximation(VCA)and the supercell method.The R3m-Lu_(2)H_(5)N predicted using the supercell method could be dynamically stable at 50 GPa,with a T_(c) of 27 K.According to the VCA method,the highest T_(c) is 22 K,obtained with 1%N-doping at 30 GPa.Moreover,the doping of nitrogen atoms into Fm3m-LuH_(3) slightly enhances T_(c),but raises the dynamically stable pressure.Our theoretical results show that the T_(c) values of N-doped LuH_(3) estimated using the Allen–Dynes-modified McMillan equation are much lower than room temperature.

Strengthening and toughening of additively manufactured Ti-6Al-4V alloy by hybrid deposition and synchronous micro-rolling

To overcome the disadvantages of inhomogeneous microstructures and poor mechanical properties of additively manufactured Ti-6Al-4V alloys,a novel technique of hybrid deposition and synchronous micro-rolling is proposed.The micro-rolling leads to equiaxed prior β grains,thin discontinuous intergranular α,and equiaxed primary α,in contrast to the coarse columnar prior β grains without the application of micro-rolling.The recrystallization by micro-rolling results in discontinuous intergranular α via the mechanism of strain and interface-induced grain boundary migration.The evolution of α globularization,driven by a solute concentration gradient,starts from the sub-boundary until the formation of equiaxed primary α.Simultaneous strengthening and toughening are achieved,which means an increase in yield strength,ultimate tensile strength,fracture elongation,and work hardening rate.The formation of α recrystallization leads to more fine grain boundaries to strengthen the yield strength,and the improvement of ductility is due to the better-coordinated deformation ability of discontinuous intergranular α and equiaxed primary α.As a result,the fracture mode in micro-rolling changes from intergranular type to transgranular type.