Effect of nanosilica addition on bioactivity and in vivo properties of calcium aluminate cement

This study aims at assessing the influence of nanosilica on the bioactivity and mechanical properties of calcium aluminate cement. For this purpose, nanosilica was applied as a replacement for calcium aluminate cement at 0, 2, 5 and 8 wt%. The main components were analyzed by scanning electron microscope coupled with surface imaging and elemental analysis, fourier transform infrared spectroscopy and X-ray diffraction analysis. To estimate the bioactivity of specimens, hydroxyapatite formation on the surface of cement paste was investigated in the simulated body fluid solution. In addition, in vivo evaluation of calcium aluminate cement was performed in subcutaneous tissue of rats. To investigate the mechanical properties, both compressive and flexural strengths were also measured. The results revealed that by increasing nanosilica up to 8 wt%, the strength enhanced. Moreover all cement paste samples with various amounts of nanosilica represented good bioactivity because of formation of bonelike apatite layer on the surface of specimens within 28 days after soaking in simulated body fluid. In vivo experiments indicated that the cement sample was absorbed by the tissue and there was no infection at the implant site. Based on the in vitro and in vivo results, the specimen with 2 wt% nanosilica represented the highest bioactivity.     

尾矿库排水管封堵技术及相关事故处理

当尾矿库库底排水管强度不能满足坝体加高的承载要求，且无法进行加固或在使用过程中出现损坏迹象时，均应对其进行封堵。排水管的封堵位置与封堵长度关系到尾矿库的安全运行，必须高度重视，防止留下安全隐患。该文结合某矿山工程事故案例，提出了排水管封堵技术要求以及因排水管承载能力不足导致的事故处理方法，为类似尾矿库工程提供参考。     

中医学视角下城市物质空间的生命要素探析

通过借鉴中医学整体观和生命观的相关理论,从认识城市有机体的生命属性入手,发现并提炼能够产生和传递城市运营所需各种能量的生命要素:廊道和功能体。阐释了其多层级、多性质和多形态的特点,提出了功能体有动力、廊道成系统、敏感点有活力的疏通策略,旨在促进城市各种能量的有机循环,从而维护城市的健康与安全,提高城市生活的效率与质量。     

Effects of different carbon sources and C/N values on nonvolatile taste components of Pleurotus eryngii

Pleurotus eryngii, the second largest industrial cultivation mushroom in China, is usually cultivated on substrates mainly consisting of sawdust and corncob. In this study, experiments were performed to determine the effects of different carbon sources and C/N values on nonvolatile taste components of P. eryngii. The effects of different carbon sources on nonvolatile taste components levels revealed that sawdust was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while corncob was beneficial to high contents of carbohydrate, polysaccharides and trehalose. At the similar C/N values, relatively higher sawdust content was beneficial to umami amino acid production, while relatively higher corncob content was beneficial to high contents of carbohydrate, polysaccharides and mannitol. Higher C/N value was beneficial to high levels of crude protein, amino acids, 5′‐nucleotides and equivalent umami concentration, while lower C/N value was beneficial to high contents of carbohydrate, polysaccharides and trehalose. These results provided information for P. eryngii fruit body industrial cultivation to obtain specific nonvolatile taste components with high levels.     

全尾砂和废石联合胶结充填体最佳配比及应用

针对红岭铅锌矿分级充填骨料来源不足、地表废石堆积污染环境的情况,提出将该矿选厂产生的全尾砂和地表废石作为充填骨料的联合胶结充填方案。分别测试了全尾砂和地表废石的物理化学性质,验证了碎石和全尾砂作为联合充填骨料的可行性。通过充填配比试验,分析了不同配比全尾砂废石充填体强度特性,得出了最佳充填配比。结果表明,充填试块的强度随灰砂比减小而减小,随养护龄期增加呈增大趋势,随充填料浆质量浓度增大而增大,最佳配比为: 胶结充填灰砂比1∶8、普通充填灰砂比1∶12,全尾砂∶废石配比4∶6,质量浓度78%。根据研究结果,在红岭铅锌矿进行了全尾砂废石充填技术工业应用,证实该技术可行。     

Separation of hematite from banded hematite jasper (BHJ) by magnetic coating

The separation of iron oxide from banded hematite jasper(BHJ) assaying 47.8% Fe, 25.6% Si O2 and 2.30%Al2O3 using selective magnetic coating was studied. Characterization studies of the low grade ore indicate that besides hematite and goethite,jasper, a microcrystalline form of quartzite, is the major impurity associated with this ore. Beneficiation by conventional magnetic separation technique could yield a magnetic concentrate containing 60.8% Fe with 51% Fe recovery. In order to enhance the recovery of the iron oxide minerals, fine magnetite, colloidal magnetite and oleate colloidal magnetite were used as the coating material. When subjected to magnetic separation, the coated ore produces an iron concentrate containing 60.2% Fe with an enhanced recovery of56%. The AFM studies indicate that the coagulation of hematite particles with the oleate colloidal magnetite facilitates the higher recovery of iron particles from the low grade BHJ iron ore under appropriate conditions.     

The link between operational practices and specific energy consumption in metal ore milling plants – Ontario experiences

An energy audit was conducted on a base metal milling facility where a top-down, bottom-up approach was presented to balance data measurements and estimates. The relation between throughput and specific electricity consumption, presented as a part-load efficiency curve for a milling operation, was established from the audit data. Unsurprisingly, the most efficient use of electricity occurred when the mill was operating at design capacity, but a survey of 14 metal mills operating in Ontario showed that 12 were operated under design capacity during 2012. For base metal flotation mills, 16–36% electricity cost savings could be realized by modification to the operating schedule, which would ensure that these facilities operated at design capacity even if plant operation was intermittent. With the Ontario electricity tariff arrangements, additional cost savings from strategic scheduling could reduce demand during coincident peak hours, which could provide financial benefit to these milling facilities.     

A new approach to detection of vortices using ultrasound

The measurement principle of vortex flowmeter is based on von Karman vortex shedding phenomenon. Frequency of vortices, behind the bluff body, is proportional to the mean flow velocity. There are different ways of detection of vortices, and different sensors are used (presser sensors, capacitive sensors, thermo-resistance sensors, ultrasonic sensors, etc.). Proposed method to vortex identification, presented in this paper is based on simultaneous detection of pair of vortices with opposite circulation, by means of two pairs of ultrasonic transducers. A beam of ultrasound, from ultrasonic transmitter to ultrasonic receiver is transmitted perpendicularly to the vortex street. The received ultrasonic signal is amplitude and phase modulated. Frequency of demodulated signal is equal to the frequency of vortices. This technique allows a number of advantages comparing to conventional solutions: reduction, or elimination of noises caused by installation vibration and disturbances in the flow, higher sensor sensitivity, which as a result leads to a possibility of a reduction of the bluff body size, i.e. reduction of the pressure drop on the flow meter, increase of the measurement range in the low flow region, the possibility of redundant operation of the flow meter, reduced measurement uncertainty, instrument technology improvements, improved reliability of the instrument, assured improved statement of complete uncertainty contributions, improved metrology of the equipment as such and calibration procedures that contribute to measuring capabilities etc. For experimental testing a prototype vortex flowmeter of a nominal inner diameter (ID) 50 mm is developed. A cylindrical bluff body for vortex shedding is used. Ultrasonic transducers based on piezo-crystal PZT-5A, inserted in the wall of the vortex meter casing are utilized. The testing of prototype ultrasonic vortex flowmeter is realized on the calibration station on the water. The results at the testing point to the possibility of measuring flow of liquid fluids at velocities less than 0.5 m/s, with an uncertainty better than ±1%.     

新人体(火用)分析模型在建筑热舒适评价中的应用

为探究人体■分析法在评估室内热环境状态中的应用,严格根据新陈代谢■的定义,在已有的两种■分析模型基础上,首先提出了更合理的新陈代谢■计算方法,建立了新的两节点■分析模型.然后利用ASHRAE数据库中的实验数据验证了所建立模型的可靠性.最后,揭示了人体■交换速率、■损失速率随室内、外环境参数的变化规律.研究结果表明:新的新陈代谢■计算方法能更准确地进行人体■分析;■损失速率比■交换速率占新陈代谢■率的比例大;操作温度25℃时,■交换速率主要包含辐射■率和对流■率;操作温度32℃时,蒸发■率和呼吸■率则是■交换速率的主要组成部分;人体■损失速率在操作温度较低或较高条件下均出现极值,将其单独用于人体热舒适评价不妥,结合■损失速率和■交换速率两者可更好地评价室内热环境状态;最小■损失速率和最小■交换速率在给定室内条件下,均在室外高温低湿工况下出现;室外温度比室外相对湿度更强烈地影响人体■损失速率和人体■交换速率.     

基于“天空地”一体化技术的安全监测系统建设与应用

西藏江达县白格村金沙江右岸于2018年10月11日和2018年11月3日先后发生2次大规模滑坡—堰塞湖堵江事件,溃堰洪水对下游拉哇库区不良地质体的稳定性造成不同程度的影响。为保障下游水电站建设安全,对拉哇库区主要不良地质体建立了基于星载InSAR技术、无人机技术和地面传感器实时监测的“天空地”一体化监测预警体系,以多维空间采集技术获取变形信息,通过智能监控平台对信息及时进行处理、分析和可视化呈现,利用平台、短信等方式向相关人员进行分级告警,取得了较好的应用效果。