One step method to synthesize flower-like hydroxyapatite architecture using mussel shell bio-waste as a calcium source

Mussel shell, a calcium-rich resource, is found plenty in nature. We have developed a novel and facile method to convert mussel shell bio-waste into hydroxyapatite (HAp) biomaterial using microwave irradiation with the aid of ethylenediaminetetraacetic acid (EDTA) as chelating agent. The obtained HAp had flower-like morphology which can be a potential candidate for developing biomaterial for orthopedic applications. Moreover, the developed method has the potential to recover the bio-waste and reduce environment pollution.     

Alcohol-assisted rapid growth of vertically aligned carbon nanotube arrays

Millimeter-to-centimeter scale vertically aligned carbon nanotube (VACNT) arrays are widely studied because of their immense potential in a range of applications. Catalyst control during chemical vapor deposition (CVD) is key to maintain the sustained growth of VACNT arrays. Herein, we achieved ultrafast growth of VACNT arrays using Fe/Al₂O₃ catalysts by ethanol-assisted two-zone CVD. One zone was set at temperatures above 850 °C to pyrolyze the carbon source and the other zone was set at 760 °C for VACNT deposition. By tuning synthesis parameters, up to 7 mm long VACNT arrays could be grown within 45 min, with a maximal growth rate of ∼280 μm/min. Our study indicates that the introduction of alcohol vapor and separation of growth zones from the carbon decomposition zone help reduce catalyst particle deactivation and accelerate the carbon source pyrolysis, leading to the promotion of VACNT array growth. We also observed that the catalyst film thickness did not significantly affect the CNT growth rate and microstructures under the conditions of our study. Additionally, the ultralong CNTs showed better processability with less structural deformation when exposed to solvent and polymer solutions. Our results demonstrate significant progress towards commercial production and application of VACNT arrays.     

多点热式气体质量流量测试方法实验研究

在已研制单点热式气体质量流量计的基础上,针对目前大口径或不规则管道气体质量流量测量中存在的问题,提出了基于多点测量的热式气体质量流量测试方法.文章对敏感元件(热膜探头)温度特性和以热膜探头为测点的多点测试方法进行了大量的试验研究.实验结果表明:多点测试方法中,以对数线性法最好;多点热式气体质量流量测试方法可以明显改善某些单点测量中出现的较大偏差,测量精度可以达到1.5%,扩展不确定度小于3.4%.     

The effect of temperature on the growth of Ag2O nanoparticles and thin films from bis(2-hydroxy-1-naphthaldehydato)silver(I) complex by the thermal decomposition of spin–coated films

Bis(2-hydroxy-1-naphthaldehydato)silver(I) complex (Ag-HNA) was prepared through the reaction of the ligand and silver nitrate. Silver oxide nanoparticles were synthesized via thermal decomposition at different temperatures by calcinating Ag complex inside a ceramic boat. The same metal precursor was used to prepare Ag₂O thin films at different temperatures by spin coating onto a glass substrate. The prepared silver complex was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, nuclear magnetic resonance (NMR) and thermogravimetric (TGA) analysis. The effects of decomposition temperatures (150, 200, 250 and 300 °C) and of the annealing temperatures for the films at 200, 250, 300 and 350 °C were studied. The surface morphologies, structural and optical properties of the nanoparticles and films were investigated. The results shows that the temperature plays a significant role in controlling nature of the nanoparticles and thin films. The X-Ray diffraction patterns of Ag₂O nanoparticles and the prepared thin films prepared revealed the face-centred cubic structures.     

Artificial neural network approach for fault detection in rotary system

The detection and diagnosis of faults in technical systems are of great practical significance and paramount importance for the safe operation of the plant. An early detection of faults may help to avoid product deterioration, performance degradation, major damage to the machinery itself and damage to human health or even loss of lives. The centrifugal pumping rotary system is considered for this research. This paper presents the development of artificial neural network-based model for the fault detection of centrifugal pumping system. The fault detection model is developed by using two different artificial neural network approaches, namely feed forward network with back propagation algorithm and binary adaptive resonance network (ART1). The training and testing data required are developed for the neural network model that were generated at different operating conditions, including fault condition of the system by real-time simulation through experimental model. The performance of the developed back propagation and ART1 model were tested for a total of seven categories of faults in the centrifugal pumping system. The results are compared and the conclusions are presented.     

流量平衡法微型风扇气动性能测试技术研究

为了解决微型风扇气动性能测试系统中微小流量测量和流量自动调节问题,提出了基于流量平衡法的微型风扇气动性能测试技术.基于流量平衡法技术原理,分析了流量平衡法管路系统空气动力特性和流量调节特性.由于采用了流量平衡管路设计,在切换不同工作管道时,整个管路系统总体阻抗基本不变,可通过开启不同测量支路来组合调节流量;理论上并联测量支路根据阀门开关,其流量非"1"即"0",可以非常方便地组合出所需流量.针对所设计的实验装置进行了流量标定实验、流量调节性能实验和微型风扇气动性能试测,实验结果表明,组合流量调节性能符合预期,微型风扇测试中组合流量调节工作正常,证明了流量平衡法适用于微型风扇气动性能测试技术.     

Searching for Escherichia coli O157 in drinking and recreational waters in Northern Greece

Escherichia coli O157:H7 has been recognized in sporadic cases and outbreaks, as an important cause of bloody diarrhea and also a leading cause of acute renal failure in children. The purpose of this study was to investigate the presence of E. coli O157 in drinking and recreational water samples from Northern Greece. For this, a total of 1974 colonies of E. coli that were isolated from 1267 water samples were recultured on sorbitol-MacConkey agar. Out of them 121 were found non-sorbitol fermenting, but none had the somatic O157 antigen. This finding supports the hypothesis that drinking and recreational waters should not be considered possible routes of E. coli O157:H7 transmission in Northern Greece.     

PPD 气体层流元件设计和使用中几种情况分析

针对 PPD 层流流量传感元件在设计制作和使用中可能出现的 3 种非标准设计或非理想情况采用数值模拟进行研究。 对于两个支路中毛细管根数不同的非标准结构设计,数值仿真得到的压降曲线、差压-流量关系与标准结构相比差别微小,根据 压降计算得到流量与准确流量之间的相对偏差在±0. 4%以内;流量测量实验数据也验证了仿真结果,说明 PPD 原理适用于两 通道毛细管数量不同的结构设计。 对制作或使用中可能出现的毛细管进出口部分堵塞情况,计算发现,差压会出现非线性偏 差,根据不同堵塞位置,可能正偏差也可能负偏差。 当两支路中毛细管直径存在偏差时,两支路阻抗特性不再相同,两支路毛细 管中流量和流速不同导致进出口局部阻力不能完全抵消,差压-流量曲线将偏离理想曲线。 上述研究结果对于 PPD 层流流量 传感技术的实际应用有一定的参考价值。     

Preparation of Chinese mystery snail shells derived hydroxyapatite with different morphology using condensed phosphate sources

Chinese mystery snail is a popular aquatic food in China, resulting in tonnes of shells as waste every year. In present work, these shells were recycled as calcium source to prepare HA. Initially, shells were found to decompose within 860 °C to porous CaO. The calcined shells were then hydrothermally utilized to synthesize HA with the help of different phosphate sources (PO₄³⁻, P₂O₇⁴⁻, P₃O₁₀⁵⁻, and P₆O₁₈⁶⁻). Under hydrothermal processing, condensed phosphate ions could be hydrolyzed into PO₄³⁻ to react with Ca²⁺. The prepared HA was subsequently characterized by XRD, FTIR, SEM, EDX and TEM. It was found condensed phosphates could result in significant changes to the morphology of HA in comparison to orthophosphate. In particular, P₆O₁₈⁶⁻ related HA appeared to be mesoporous. The cytocompatibility of different phosphate source related HA was also investigated.     

Study on the parallel pressure differential type gas laminar flow sensing technique

Parallel pressure differential (PPD) type laminar flow sensing technique was invented several years ago to reduce nonlinear effect in a traditional laminar flow element (LFE). In this paper, the internal flow of each branch in a PPD LFE is numerically simulated for gas flow. The results show that the relative deviation of the pressure drops of the two branches in a PPD LFE is within ±0.05% as inlet mass flow being the same, indicating that the flow resistance characteristics of the two branches are consistent, which means that the hypothesis of a same flow rate for the two branches in a real PPD LFE is tenable. There is little difference, ±0.01%, in the local pressure losses of the two upstream capillaries outlet flows, which can be ignored in a real measurement, further verifying that the theoretical analysis of the PPD principle is reliable. Capillary length effect in a PPD LFE is also examined. The bigger capillary length, the higher measurement precision can be achieved for a certain length range. For instance, it is suggested that the length of the short components should not be shorter than the laminar flow dimensionless entrance length defined by X_e (L_e/d/Re, where L_e is the entrance length) = 0.035, for flow measurement uncertainty within ±1.0%. The simulation and experiment results of gas flow show that the suitable value of K_exp is 1, and in the flow range of (0.0256–5.2985) m³/h measurement error of a PPD LFE is within ±0.8% only with expansion correction, indicating that the PPD laminar flow measurement technique is suitable for the gas flow.