Removal of basic yellow dye from aqueous solution by sorption on green alga Caulerpa scalpelliformis

Dynamic batch experiments were carried out for the biosorption of basic yellow dye on to the green macroalgae Caulerpa scalpelliformis. The factors affecting the sorption process such as the initial concentration of the dye and pH of the solution, the adsorbent dosage and the time of contact were studied. The sorption kinetics followed pseudo-second order kinetic model. The Caulerpa species exhibited a maximum uptake of 27 mg of dye per gram of seaweed. The Boyd's plot confirmed the external mass transfer as the rate-limiting step. The average effective diffusion coefficient was found to be 2.47 x 10(-4)cm(2)/s. Sorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implies a heterogeneous sorption phenomenon. Various thermodynamic parameters such as enthalpy of sorption DeltaH degrees , free energy change DeltaG degrees and entropy DeltaS degrees were estimated. The negative value of DeltaH degrees and negative values of DeltaG degrees show the sorption process is exothermic and spontaneous. The negative value of entropy DeltaS degrees shows the decreased randomness at the solid-liquid interface during the sorption of dyes onto green seaweed.     

Application of fuzzy cognitive maps for crack categorization in columns of reinforced concrete structures

The detection of damage at an early stage that affects the supporting element of civil structures proves to be very significant to save invaluable human life and valuable possessions. In this research work, the severity of cracks in the supporting column is assessed using a new technique. This piece of research study uses the soft computing method of fuzzy cognitive map (FCM) to model the domain experts’ knowledge and the knowledge assimilated through relevant literature to grade the severity of cracks in supporting column. The FCM grading model is further improved by using the Hebbian learning algorithms. The presented work demonstrates the classification and prediction capabilities of FCM for the respective structural health monitoring application, using two well-known and efficient FCM learning approaches viz. nonlinear Hebbian learning (NHL) and data-driven nonlinear Hebbian learning (DD-NHL). The proposed crack severity grading model classifies the cracks in supporting column into three categories, namely fine crack, moderate crack and severe crack. The proposed model uses DD-NHL algorithm. DD-NHL is trained with 70 records and tested with 30 records and gives an overall classification accuracy of 96 %. The obtained results are better compared to other popular machine learning-based classifiers. The proposed method helps even the non-experts to find the possible causes of crack and reports them to structural engineers, to start maintenance in an appropriate stage, using various crack control techniques. Also, a software tool for crack categorization was developed based on the FCM method and its learning capabilities. Thus, it is easier for the users/civil engineers to use this software to make decisions in civil engineering domain and improve their knowledge about the health of the structure.

     

In vivo andin vitro evaluation of a biomachinable glassceramic

In this paper we describe the toxicological tests done on a machinable glassceramic, prepared at the Defence Metallurgical Research Laboratory. Tests show no toxicity and biocompatibility is inferred.     

Simplified synthesis of K<Subscript>2</Subscript>CO<Subscript>3</Subscript>-promoted hydrotalcite based on hydroxide-form precursors: Effect of Mg/Al/K<Subscript>2</Subscript>CO<Subscript>3</Subscript> ratio on high-temperature CO<Subscript>2</Subscript> sorption capacity

Hydrotalcite was synthesized from hydroxide-form precursors to prepare a novel high-temperature CO₂ sorbent, and the effect of Mg/Al ratio on CO₂ sorption was studied. To enhance the CO₂ sorption capacity of the sorbent, K₂CO₃ was coprecipitated during the synthetic reaction. X-ray diffraction analysis indicated that the prepared samples had a well-defined crystalline hydrotalcite structure, and confirmed that K₂CO₃ was successfully coprecipitated in the samples. The morphology of the hydrotalcite was confirmed by scanning electron microscopy, and N₂ adsorption analysis was used to estimate its surface area and pore volume. In addition, thermogravimetric analysis was used to measure its CO₂ sorption capacity, and the results revealed that the Mg: Al: K₂CO₃ ratio used in the preparation has an optimum value for maximum CO₂ sorption capacity.     

制浆造纸厂富铁污泥中Fe3+的电化学还原研究

采用电化学法将制浆造纸厂废水Fe^nton氧化产生的难处理富铁污泥中的Fe^3+还原为Fe^2+,以便于其再利用。研究表明,以不锈钢为阴极材料可较大幅度降低Fe^3+还原的过电位;当Fe^3+质量浓度为2000 mg/L时无需辅助电解质,在极水比为0.48 cm^2/mL,电流密度为0.65 mA/cm^2的条件下反应2 h,Fe^2+再生率可达60.1%,电流效率为92.1%。将酸处理后的富铁污泥溶液在上述条件下还原3 h,Fe^2+再生率达68.8%,电流效率近100%。电化学法是富铁污泥中Fe^3+再利用的可行方法。     

Molecular interactions of graphene with HIV-Vpr,Nef and Gag proteins: A new approach for treating HIV infections

Graphene draws considerable attention among biomedical researchers because of its unique physical, chemical and biological properties. The wide applications of graphene in the biomedical arena such as diagnostics, drug immobilization and drug delivery were well documented in the literature. However the therapeutic potential of the graphene towards retroviruses and the interactions of the graphene with receptors/proteins are still unexplored. Herein we report the antagonistic molecular interactions of graphene with the three key target proteins of HIV infections namely HIVVpr, Nef and Gag proteins. The docking investigations were performed to find the binding energy of the graphene ligands to the key target proteins of HIV. The high binding affinity of the graphene to these proteins indicates the antagonistic molecular interaction of graphene to the disease targets. The therapeutic potential of graphene was also studied by changing the size and the number of layers of the graphene. The experimental results confirm the good therapeutic potential of the graphene to combat HIV mediated retroviral infections.     

基于单层超表面的双频太赫兹波线偏振变圆偏振转换器

提出了一种基于单层超表面的双频太赫兹波线偏振变圆偏振转换器。该偏振转换器采用两个不同尺寸的十字型金属缝阵列结构形成两个线偏振变圆偏振转换频点,从而实现双频的太赫兹波线偏振变圆偏振转换。计算结果表明,设计的偏振转换器能在0.760THz和1.068THz将一束线偏振太赫兹波转换为圆偏振太赫兹波。该双频的线偏振变圆偏振转换器仅由单层的超表面组成,结构简单易于制备,因而为操控电磁波和设计新颖的太赫兹波器件提供了参照。     

Random Bit Extraction for Secret Key Generation in MANETs

Wireless Personal Communications - Various channel coding techniques have been used for free space optical (FSO) links to alleviate the effects of fading, induced due to turbulence. In this paper,...     

Comparison of thermal fatigue behaviour of ASTM A 213 grade T-92 base and weld tubes

Super-heater tubes are subjected to alternate heating and cooling in power plants causing them to crack and eventually fail. This phenomenon is referred to as “thermal fatigue.” In this paper, a laboratory simulation for reproducing the thermal fatigue phenomenon is developed to determine the number of cycles necessary before failure occurs in super-heater tubes. The temperature and strain distributions along the specimen were computed theoretically using ANSYS software for the applied temperature condition. The thermal fatigue test was conducted for both base and shielded metal arc (SMA) welded tubes separately and both passed in the non-destructive tests. These tubes were subjected to thermal cycles from 800°C (accelerated temperature) to room temperature. Oxy-acetylene heating setup was utilized as a heating source, and a water bath was utilized for quenching purposes. The tests were carried out until open cracks were identified. Surface cracks were identified in the base and weld tubes after 90 and 60 cycles respectively. This study reveals that heating and cooling cause thermal fatigue, initiate cracks in the tubes.     

碳纤维拉索缺陷的电磁层析成像有限元仿真

碳纤维复合材料具有高比强度、高比刚度、耐腐蚀和抗疲劳等优点,是大跨度结构拉索的理想型材料。本文基于电磁层析成像技术采用有限元方法对碳纤维拉索的断股和脱粘缺陷进行仿真研究,设计了一种8线圈圆周型传感器阵列,探究了传感器尺寸、激励电流大小与磁感应强度的关系,根据仿真电磁信号研究了LBP算法、Tikhonov算法和Landweber算法3种重建算法对不同拉索缺陷重建图像质量的影响。结果表明,在研究范围内随着传感器线圈直径的减小和激励电流的增大,磁感应强度逐渐增大,并在线圈直径为5 mm和激励电流为1 A时达到最大值;与其他图像重建方法相比,Tikhonov算法能够更好的平衡图像重建效果和成像质量,更适用于碳纤维拉索缺陷检测图像的重建过程。此外,在传感器阵列固定的情况下将拉索缺陷旋转,分析了不同投影角度对缺陷成像效果的影响。本研究旨在为实验条件下碳纤维拉索的传感器阵列设计和缺陷检测成像提供参考依据。