Enhancing fly ash utilization in backfill materials treated with CO_(2)carbonation under ambient conditions

The environmental concerns resulting from coal-fired power generation that produces large amounts of CO_(2)and fly ash are of great interest.To mitigate,this study aims to develop a novel carbonated CO_(2)-fly ash-based backfill(CFBF)material under ambient conditions.The performance of CFBF was investigated for different fly ash-cement ratios and compared with non-CO_(2)reacted samples.The fresh CFBF slurry conformed to the Herschel-Bulkley model with shear thinning characteristics.After carbonation,the yield stress of the fresh slurry increased significantly by lowering fly ash ratio due to gel formation.The setting times were accelerated,resulting in approximately 40.6%of increased early strength.The final strength decreased when incorporating a lower fly ash ratio(50%and 60%),which was related to the existing heterogeneous pores caused by rapid fluid loss.The strength increased with fly ash content above 70%because additional C-S(A)-H and silica gels were characterized to precipitate on the grain surface,so the binding between particles increased.The C-S(A)-H gel was developed through the pozzolanic reaction,where CaCO_(3)was the prerequisite calcium source obtained in the CO_(2)-fly ash reaction.Furthermore,the maximum CO_(2)uptake efficiency was 1.39 mg-CO_(2)/g-CFBF.The CFBF material is feasible to co-dispose CO_(2)and fly ash in the mine goaf as negative carbon backfill materials,and simultaneously mitigates the strata movement and water lost in post-subsurface mining.

Controllable and large-area growth of ZnO nanosheet arrays under ambient condition as superior anodes for scalable aqueous batteries

Two-dimensional(2D)oxides have been the focus of substantial research interest recently,owing to their fascinating physico-chemical properties.However,fabrication of large-area 2D oxide materials in a controlled manner under mild conditions still remains a formidable challenge.Herein,we develop a facile and universal strategy based on the sonochemistry approach for controllable and large-area growth of quasi-aligned single-crystalline ZnO nanosheets on a Zn substrate(Zn@SC-ZnO)under ambient conditions.The obtained ZnO nanosheets possess the desired exclusively exposed(001)facets,which have been confirmed to play a critical role in significantly reducing the activation energy and facilitating the stripping/plating processes of Zn.Accordingly,the constructed Zn@SC-ZnO||Zn@SC-ZnO symmetric cell has very low polarization overpotential down to~20 mV,with limited dendrite growth and side reactions for Zn anodes.The developed Zn@SC-ZnO//MnO_(2)aqueous Zn-ion batteries(ZIBs)show a voltage efficiency of 88.2%under 500 mA g^(-1)at the stage of 50%depth of discharge,which is state of the art for ZIBs reported to date.Furthermore,the as-assembled large-size cell(5 cm×5 cm)delivers an open circuit potential of 1.648 V,and can be robustly operated under a high current of 20 mA,showing excellent potential for future scalable applications.

Porous LaFeO3 nanofiber with oxygen vacancies as an efficient electrocatalyst for N2 conversion to NH3 under ambient conditions

Electrocatalytic N2 reduction to NH3 under ambient conditions is an eco-friendly and sustainable alternative to the traditional Haber-Bosch process. However, inhibited by the high activation barrier of N2, this process needs efficient electrocatalysts to adsorb and activate the N2, enabling the N2 reduction reaction(NRR). Herein, we report that porous LaFeO3 nanofiber with oxygen vacancies acts as an efficient NRR electrocatalyst with abundant active sites to enhance the adsorption and activation of N2. When tested in 0.1 M HCl, such electrocatalyst achieves a high Faradaic efficiency of 8.77% and a large NH3 yield rate of 18.59 μg h–1 mgcat–1.at-0.55 V versus reversible hydrogen electrode. This catalyst also shows high long-term electrochemical stability and excellent selectivity for NH3 formation. Density functional theory calculations reveal that, by introducing oxygen vacancy on LaFeO3, the subsurface metallic ions are exposed with newly localized electronic states near the Fermi level, which facilitates the adsorption and activation of N2 molecules as well as the subsequent hydrogenation reactions.

Defect and interface engineering for electrochemical nitrogen reduction reaction under ambient conditions

Electrochemical nitrogen reduction reaction(e-NRR)under ambient conditions is an emerging strategy to tackle the hydrogen-and energy-intensive operations for traditional Haber-Bosch process in industrial ammonia(NH_(3))synthesis.However,the e-NRR performance is currently impeded by the inherent inertness of N_(2) molecules,the extremely slow kinetics and the overwhelming competition from the hydrogen evolution reaction(HER),all of which cause unsatisfied yield and ammonia selectivity(Faradaic efficiency,FE).Defect and interface engineering are capable of achieving novel physical and chemical properties as well as superior synergistic effects for various electrocatalysts.In this review,we first provide a general introduction to the NRR mechanism.We then focus on the recent progress in defect and interface engineering and summarize how defect and interface can be rationally designed and functioned in NRR catalysts.Particularly,the origin of superior NRR catalytic activity by applying these approaches was discussed from both theoretical and experimental perspectives.Finally,the remaining challenges and future perspectives in this emerging area are highlighted.It is expected that this review will shed some light on designing NRR electrocatalysts with excellent activity,selectivity and stability.

Theoretical analysis of the surface temperature regulation of an infrared false target subjected to periodical ambient conditions

Infrared false target is an important mean to induce the infrared-guided weapons,and the key issue is how to keep the surface temperature of the infrared false target to be the same as that of the object to be protected.One-dimensional heat transfer models of a metal plate and imitative material were established to explore the influences of the thermophysical properties of imitative material on the surface temperature difference（STD） between the metal plate and imitative material which were subjected to periodical ambient conditions.It is elucidated that the STD is determined by the imitative material’s dimensionless thickness（dim*,） and the thermal inertia(Pim).When dim* is above 1.0,the STD is invariable as long as Pim is a constant.And if the dimensionless thickness of metal plate（d,m*） is also larger than 1.0,the STD approaches to zero as long as Pimis the same as the thermal inertia of metal plate（Pm）.When dim* is between 0.08 and 1,the STD varies irregularly with Pim and dim*.However,if dm* is also in the range of 0.08-1,the STD approaches to zero on condition that Pim=Pm and dim*= dm*.If dim*,is below 0.08,the STD is unchanged when Pimdim* is a constant.And if dm* is also less than 0.08,the STD approaches to zero as long as Pimdim* = Pmdm*.Furthermore,an applicationoriented discussion indicates that the imitative material can be both light and thin via the application of the phase change material with a preset STD because of its high specific heat capacity during the phase transition process.

Improvement on the performance of perovskite solar cells by doctor-blade coating under ambient condition with hole-transporting material optimization

Numerous fabrication methods have been developed for high-efficiency perovskite solar cells(PSCs). However, these are limited to spin-coating processes in a glove box and are yet to be commercialized. Therefore, there is a need to develop a controllable and scalable deposition technique that can be carried out under ambient conditions. Even though the doctor-blade coating technique has been widely used to prepare PSCs, it is yet to be applied to high-efficiency PSCs under ambient conditions(RH ~45%, RT ~25 °C). In this study, we conducted blade-coating fabrication of modified high-efficiency PSCs under such conditions. We controlled the substrate temperature to ensure phase transition of perovskite and added dimethyl sulfoxide(DMSO) to the perovskite precursor solution to delay crystallization, which can facilitate the formation of uniform perovskite films by doctor-blade coating. The as-prepared perovskite films had large crystal domains measuring up to 100 μm. Solar cells prepared from these films exhibited a current density that was enhanced from 17.22 to 19.98 m A/cm^2 and an efficiency that was increased from 10.98% to 13.83%. However, the open-circuit voltage was only 0.908 V, probably due to issues with the hole-transporting layer. Subsequently, we replaced poly(3,4-ethylenedioxythiophene) polystyrene sulfonate(PEDOT:PSS) with Ni O x as the hole-transporting material and then prepared higher-quality perovskite films by blade-coating under ambient conditions. The as-prepared perovskite films were preferably orientated and had large crystal domains measuring up to 200 μm;The open-circuit voltage of the resulting PSCs was enhanced from 0.908 to 1.123 V, while the efficiency increased from 13.83% to 15.34%.

Ambient-Condition Strategy for Production of Hollow Ga_(2)O_(3)@rGO Crystalline Nanostructures Toward Efficient Lithium Storage

Crystallineγ-Ga_(2)O_(3)@rGO core-shell nanostructures are synthesized in gram scale,which are accomplished by a facile sonochemical strategy under ambient condition.They are composed of uniformγ-Ga_(2)O_(3)nanospheres encapsulated by reduced graphene oxide(rGO)nanolayers,and their formation is mainly attributed to the existed opposite zeta potential between the Ga_(2)O_(3)and rGO.The as-constructed lithium-ion batteries(LIBs)based on as-fabricatedγ-Ga_(2)O_(3)@rGO nanostructures deliver an initial discharge capacity of 1000 mAh g^(-1)at 100 mA g^(-1)and reversible capacity of 600 mAh g^(-1)under 500 mA g^(-1)after 1000 cycles,respectively,which are remarkably higher than those of pristineγ-Ga_(2)O_(3)with a much reduced lifetime of 100 cycles and much lower capacity.Ex situ XRD and XPS analyses demonstrate that the reversible LIBs storage is dominant by a conversion reaction and alloying mechanism,where the discharged product of liquid metal Ga exhibits self-healing ability,thus preventing the destroy of electrodes.Additionally,the rGO shell could act robustly as conductive network of the electrode for significantly improved conductivity,endowing the efficient Li storage behaviors.This work might provide some insight on mass production of advanced electrode materials under mild condition for energy storage and conversion applications.

陕西省环境气象条件评估指数时空变化特征研究

基于陕西省10地市2015—2020年PM_(2.5)浓度实况监测数据和气象条件评估指数EMI,统计分析EMI和PM_(2.5)相关性及近年EMI的时空分布特征,定量评估气象条件变化及综合治理措施对陕西环境空气质量的影响。结果表明:陕西省2015—2020年EMI可较好地表征和评估气象条件变化导致的PM_(2.5)浓度变化。2015—2020年EMI呈线性降低趋势,气象条件持续向好。月EMI均呈明显的单谷分布特征,EMI冬半年大,夏半年小。各区域EMI总体上呈关中高、陕南次之、陕北最低的分布特点,关中中部、东部EMI最大。EMI正距平百分比高值区主要分布在关中地区,各年关中均有60%以上面积正距平,其中2016年冬季关中83.0%面积正距平,37.5%面积正距平超过100%。2020年陕西省各区域环境空气质量较2015—2019年均有明显改善,全省PM_(2.5)浓度较前5 a平均降低24.8%,全省气象条件改善使PM2.5浓度较近5 a降低16.4%,排放变化使得PM_(2.5)浓度较前5 a平均下降9.4%,可见,近年陕西省大气污染综合治理措施成果显著,环境质量明显改善。

不同暖箱湿度对早产儿体重的影响

目的:探讨不同暖箱湿度对早产儿体重的影响。方法:2022年3月-2023年9月选取本院出生的100例早产儿(<孕37周),随机数表法分为两组各50例,分别给予不同暖箱内环境湿度护理(出生后1周内暖箱湿度达85%~90%为观察组、常规55%~65%湿度为对照组)。记录早产儿出生后1周内体重变化、恢复时间和并发症的发生情况,并对比新生儿皮肤状况评分表(NSCS)得分。结果:观察组早产儿出生后第3d体重减少量(32.8±10.3g)小于对照组(43.1±13.8g),出生后第7d体重增加量(40.6±12.7g)大于对照组(30.5±9.0g),NSCS量表中皮肤干燥度(1.45±0.31分)、皮肤损伤(1.20±0.37分)及总分(3.83±1.02分)均小于对照组(1.70±0.25分、1.40±0.28分、4.43±0.95分),早产儿住院期间体重日均增加值(19.1±5.7g)大于对照组(15.6±4.2g),恢复至出生体重时间(6.00±1.45d)、住院时间(15.60±5.13 d)均短于对照组(7.39±1.50 d、18.67±5.97 d)(均P<0.05)。两组早产儿肺炎、上呼吸道感染、皮肤感染、腹泻、鹅口疮等发生率以及院内感染总发生率均无差异(P>0.05)。结论:适当增加婴儿暖箱内环境湿度可减缓早产儿早期体重降低、促进早产儿体重增长,降低皮肤损伤风险,且不会增加感染风险,有利于生长发育。

不同环境温度条件酿制的传统黄酒的滋味特征差异分析

传统黄酒是中华酿造技艺之瑰宝,而其半开放的酿造环境易受环境温度条件等影响而导致产品风味品质不稳定。本研究以不同环境温度条件酿制的传统黄酒为研究对象(前性酒(S1)、中性酒(S2和S3)、后性酒(S4)),采用定量描述感官评价分析4批次传统黄酒的静态滋味强度差异,采用时间-强度感官评价和动态主导属性测试分析饮用过程中滋味特征的动态变化及不同批次间的差异,采用电子舌技术分析味觉风味轮廓差异,并结合偏最小二乘法建立滋味预测模型。结果表明:S2和S3的滋味和谐饱满,鲜味突出,苦味和后苦味强度弱;4批次传统黄酒的主导滋味属性按时间先、后均为酸味、苦味和鲜味,S3的苦味优势属性结束最早(85 s),S4的苦味消逝时间最久(110 s),S3的鲜味占据主导优势的时间最早,其次为S2、S1和S4。电子舌响应信号与酸、苦和后苦味感官评分具有较好的相关性,后苦味模型最稳健,模型的相关系数r为0.976。静态和动态感官评价结合电子舌可全面评价传统黄酒滋味特征差异,环境温度条件对传统黄酒苦味及后苦味具有重要影响。

机器人使用与职业伤害——理论机制与中国证据

党的二十大报告指出要把保障人民健康放在优先发展的战略位置,与此同时工业机器人的广泛应用对职业伤害的影响日益受到关注。基于全国人口普查数据、国际机器人联合会数据、区域层面工伤数据与中国劳动力动态调查数据,系统地考察了机器人使用对职业伤害的影响效果与作用机制。研究发现,机器人使用显著减少了职业伤害,结论在内生性处理、替换被解释变量、排除国际贸易的影响和排除某些行业趋势的影响等一系列稳健性检验下仍然成立。异质性分析表明,机器人使用能够显著降低工作场所内和机器人使用后期的职业伤害,但对工作场所外和机器人使用前期的影响不显著。相较于在制造业就业比例较低的地区,机器人使用对职业伤害的影响在制造业就业比例较高地区的作用更大。机制分析发现,任务的重新分配和工作条件的改善是机器人使用影响职业伤害的重要渠道。具体而言,机器人使用一方面可以取代高体力、高风险任务,推动这些工人从事体力强度较低、受伤风险较低的任务和职业;另一方面有助于减少工作时长、降低工作强度和优化工作环境,从而改善工作条件。研究为通过智能制造转型提升劳动者职业健康提供了中国的经验证据,为“健康中国”战略目标的实现提供了可行的路径。

数学概率问题解决学习中的测试效应及有效促进

研究通过3个实验,探讨了材料复杂度对数学概率问题解决中测试效应的影响,并在此基础上,进一步考察提取方式对学习者运用提取练习策略解决复杂概率问题的作用效果。结果发现:(1)相比于重学,通过提取练习策略学习简单数学概率问题时的后测成绩更佳,出现测试效应。在学习复杂数学概率问题时,通过提取练习和重学的后测成绩差异不显著,未出现测试效应;(2)相比于重学和自由回忆提取练习,通过线索提取学习复杂数学概率问题的后测成绩更高;(3)相比于重学和无反馈的自由回忆提取练习,通过加入反馈的自由回忆提取练习学习复杂数学概率问题的后测成绩更好。该结果表明,材料难度影响学习者运用提取练习策略学习问题解决任务的效果,并且线索提取练习方式和提供反馈的自由回忆提取练习方式均能有效促进学生学习复杂概率问题解决任务的效果。

地域与建筑类型对低环温空气源热泵减碳量定量评估的影响分析

针对低温空气源热泵减碳量定量评估方法缺失的问题,基于DeST与GB 55015—2021的规定得出该类机组的标准化年使用条件,并采用哈尔滨实测气象数据进行了验证。依据T/CECA-G 0164—2022的规定,提出了低温空气源热泵减碳量的评估方法。通过实验室的测试数据及自行编制的计算软件对2台样机进行了减碳量评估,结果表明:在不同建筑类型应用时,低环温空气源热泵减碳量差距最大为74%;不同城市的减碳量差距最大为28%;寒假的设置对学校建筑减碳量的影响为24%。研究结果对低温空气源热泵的应用具有参考价值。

工位送风空调系统在汽车工厂应用的探讨

结合实际工程案例,总结了国内若干汽车工厂车间工位送风空调系统的技术数据,通过CFD模拟及实际运行数据的分析,对比了工位局部通风空调系统和全车间空调系统在不同工位数量时的优缺点;通过分析送风口尺寸、布置间距对工位温度及风速的影响,为汽车工厂选择合理的空调降温方案提供了设计参考依据。

Ambient-condition strategy for rapid mass production of crystalline gallium oxide nanoarchitectures toward device application

Currently,the synthesis of nanostructures still encounters two grand challenges:one is the often-required high temperatures and/or high pressures,and the other is the scalable fabrication.Here,to break through such bottlenecks,we demonstrate an ambient-condition strategy for rapid mass production of fourthgeneration semiconductor Ga_(2)O_(3)nanoarchitectures assembled by single-crystalline nanosheets in a controlled manner based on sonochemistry.Their growth is fundamentally determined by the introduced ethanediamine in rationally designed source materials,which could not only protect the metal Ga against reacting with H_(2)O into GaOOH,but facilitate the reaction of Ga with OH·radicals for target crystalline Ga_(2)O_(3)nanostructures.As a proof of concept for applications,the as-fabricated Ga_(2)O_(3)nanoarchitectures exhibit superb performances for electromagnetic wave absorption with a reflection loss value of 52.2 dB at 8.1 GHz,and ammonia sensing with high sensitivity and selectivity at room temperature,representing their bright future to be commercially applied in modern devices.

Ultrafast metal oxide reduction at Pd/PdO_(2) interface enables onesecond hydrogen gas detection under ambient conditions

Here,we report a Pd/PdO_(x) sensing material that achieves 1-s detection of 4% H_(2) gas(i.e.,the lower explosive limit concentration for H_(2))at room temperature in air.The Pd/PdO_(x) material is a network of interconnected nanoscopic domains of Pd,PdO,and PdO_(2).Upon exposure to 4% H_(2),PdO and PdO_(2) in the Pd/PdO_(x) are immediately reduced to metallic Pd,generating over a>90% drop in electrical resistance.The mechanistic study reveals that the Pd/PdO_(2) interface in Pd/PdOx is responsible for the ultrafast PdO_(x) reduction.Metallic Pd at the Pd/PdO_(2) interface enables fast H_(2) dissociation to adsorbed H atoms,significantly lowering the PdO2 reduction barrier.In addition,control experiments suggest that the interconnectivity of Pd,PdO,and PdO2 in our Pd/PdO_(x) sensing material further facilitates the reduction of PdO,which would otherwise not occur.The 1-s response time of Pd/PdO_(x) under ambient conditions makes it an excellent alarm for the timely detection of hydrogen gas leaks.

某型涡扇发动机地面台架起动试验研究

为了分析大气环境温度对发动机起动过程的影响,采用三段积分法计算发动机起动特性,开展了不同大气环境温度条件下某型涡扇发动机地面起动试验研究。结果表明:冷态条件下,发动机的起动特性与理论计算结果一致,标准大气温度下发动机起动时间和脱开时间均为最短;热态条件下,发动机起动最快时的大气温度比理论计算温度低2 K左右,起动时间和脱开时间均快于冷态时间(约快2.9 s);热态起动比冷态起动的风扇、压气机转速出现时间早约0.5 s,热态供油压力、排气温度的建立更早;分析认为,热态试验结果比理论计算温度低的原因与大气温度变化引起的燃油粘度、滑油粘度、空气密度等变化及热态发动机焓值的变化有关。该试验研究结果可为地面起动试验提供参考。

An optimal scheduling algorithm based on task duplication

When the communication time is relatively shorter than the computation time for every task, the task duplication based scheduling (TDS) algorithm proposed by Darbha and Agrawal generates an optimal schedule. Park and Choe also proposed an extended TDS algorithm whose optimality condition is less restricted than that of TDS algorithm, but the condition is very complex and is difficult to satisfy when the number of tasks is large. An efficient algorithm is proposed whose optimality condition is less restricted and simpler than both of the algorithms, and the schedule length is also shorter than both of the algorithms. The time complexity of the proposed algorithm is O(v2), where v represents the number of tasks.

Partial Nitrification from Domestic Wastewater by Aeration Control at Ambient Temperature

The objective of this paper was to examine the feasibility of partial nitrification from raw domestic wastewater at ambient temperature by aeration control only. Airflow rate was selected as the sole operational pa-rameter. A 14L sequencing batch reactor was operated at 23℃ for 8 months, with an input of domestic wastewater. There was a programmed decrease of the airflow rate to 28L·h-1, the corresponding average dissolved oxygen (DO) was 0.32mg·L-1, and the average nitrite accumulation rate increased to 92.4% in 3 weeks. Subsequently, further in-crease in the airflow rate to 48L·h-1 did not destroy the partial nitrification to nitrite, with average DO of 0.60mg·L-1 and nitrite accumulating rate of 95.6%. The results showed that limited airflow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate and that this system showed relatively stability at higher airflow rate independent of pH and temperature. About 50% of influent total nitrogen was eliminated coupling with partial nitrification, taking the advantage of low DO during the reaction.

MMRGait-1.0:多视角多穿着条件下的雷达时频谱图步态识别数据集

步态识别作为一种生物识别技术,在实际生活中通常被认为是一项检索任务。然而,受限于现有雷达步态识别数据集的规模,目前的研究主要针对分类任务且局限于单一行走视角和相同穿着条件,这限制了基于雷达的步态识别在实际场景中的应用。该文公开了一个多视角多穿着条件下的雷达步态识别数据集,该数据集使用毫米波雷达采集了121位受试者在多种穿着条件下沿不同视角行走的时频谱图数据,每位受试者共采集8个视角,每个视角采集10组,其中6组为正常穿着,2组为穿大衣,2组为挎包。同时,该文提出一种基于检索任务的雷达步态识别方法,并在公布数据集上进行了实验,实验结果可以作为基准性能指标,方便更多学者在此数据集上开展进一步研究。