Fitting Spheres to Range Data From 3-D Imaging Systems

Two error functions used for nonlinear least squares (LS) fitting of spheres to range data from 3-D imaging systems are discussed: the orthogonal error function and the directional error function. Both functions allow unrestricted gradient-based minimization and were tested on more than 40 data sets collected under different experimental conditions (e.g., different sphere diameters, instruments, data density, and data noise). It was found that the orthogonal error function results in two local minima and that the outcome of the optimization depends on the choice of starting point. The centroid of the data points is commonly used as the starting point for the nonlinear LS solution, but the choice of starting point is sensitive to data segmentation and, for some sparse and noisy data sets, can lead to a spurious minimum that does not correspond to the center of a real sphere. The directional error function has only one minimum; therefore, it is not sensitive to the starting point and is more suitable for applications that require fully automated sphere fitting.     

Refractive index changes in AlGaN/GaN heterostructure field-effect transistors

Using the envelope wavefunction approximation and the compact density matrix formalism, we have investigated theoretically the linear and nonlinear refractive index changes in AlGaN/GaN quantum well heterostructures aimed for designing electro-optical modulators. The confining potential in the heterostructures is assumed to be semiparabolic. Simulated results reveal that the refractive index changes strongly depend on both the Al composition and the delta-doping concentration. On the other hand an applied electric field further enhances the refractive index changes. Compared with AlGaAs/GaAs heterostructures and quantum dots, the amount of the refractive index is larger in the AlGaN/GaN quantum well heterostructures studied. The fact to have a large refractive index change leads to the use of relatively weaker incident beam intensities.     

Peptic hydrolysis of bovine beta‐lactoglobulin under microwave treatment reduces its allergenicity in an ex vivo murine allergy model

In this study, the in vivo allergenicity of bovine beta‐lactoglobulin (BLG) in peptic whey protein hydrolysates generated during microwave and conventional heating treatments was assessed. The allergenicity of the hydrolysates was explored by studying the reaction of the murine jejunum from previously immunised Balb/c mice to treated BLG in an Ussing chamber. Intestinal anaphylactic reactions after stimulation of the gut‐associated immune system are a good indicator of potential in vivo allergenicity of whey hydrolysates. Fifty‐two per cent of BLG was hydrolysed by pepsin after only 3 min of microwave irradiation at 200 watts (W), yet it remained intact under conventional heating. Far‐ and near‐UV circular dichroism spectra indicated significant changes in BLG secondary and tertiary structures with microwave irradiation at 200 W. Pepsin whey protein hydrolysates obtained with microwave irradiation at 200 W for 3 min did not stimulate secretion of chloride in the Ussing chamber, as shown by the intensity of the short current values recorded (27.86 μA cm^?2), compared to the conventional pepsin hydrolysates (68.21 μA cm^?2). This demonstrates the low allergenicity of whey protein hydrolysates generated in this manner. These results confirm that microwave treatment combined with peptic hydrolysis could be applied to produce low allergenicity milk peptides.     

A Comparative First-Principles Study of Fe-, Co- and FeCo-Doped ZnO with Wurtzite and Zinc Blende Structures

First-principles study of the electronic and magnetic properties of zinc-blende and wurtzite structures of Fe-, Co-, and FeCo-doped ZnO is presented. It is found that after doping, this diamagnetic material becomes ferromagnetic and half-metallic. It is also shown that the half-metallicity may be obtained for ZnFeO, ZnCoO, and ZnFeCoO. The analysis of the spin density reveals that the ferromagnetic phase is due to the ferromagnetic coupling between the p?Cd states. The effects of Fe on the magnetic properties of ZB and WZ Fe-doped ZnO compound have been investigated with the GGA calculations. In order to understand the role of Fe atom in the ferromagnetism, the density of states both in the presence and absence of Co doping, were calculated. The obtained results show the presence of coupling between Co and Fe atoms through the spin-split impurity band exchange mechanism. More importantly, the calculations show that the magnetic moment changes sensitively with the type of structure of ZnO, zinc-blende, or wurtzite. A discussion by comparing the results obtained in this study and the experimental results reported in the literature of similar systems show a very good agreement.     

Pile-clayey soil interaction analysis by boundary element method

This paper is an attempt to solve the soil-pile interaction problems using the boundary element method(BEM).A computer package called PGroupN,which deals mainly with the analysis of the pile group problem,is employed in this study.Parametric studies are carried out to assess the impacts of the pile diameter,pile length,ratio of spacing to diameter and the thickness of soil stratum.The external load is applied incrementally and,at each increment,a check is made that the stress state at the pile-soil interfaces does not violate the yield criteria.This is achieved by specifying the limited stresses of the soil for the axial pile shaft capacity and end-bearing resistance.The elements of the pile-soil interface yielded can take no additional load,and any increase in load is therefore redistributed between the remaining elements until all elements have failed.Thus,by successive application of loading increments,the entire load-displacement relationship for the pile group is determined.It is found that as the applied load reaches the ultimate bearing capacity of the pile group,all the piles will share the same amount of load.An exception to this case is for the center pile in a group of 9 piles embedded in clay,which is not consistent with the behaviors of the other piles in the group even if the load reaches the ultimate state.For the 4 piles group embedded in clay,the maximum load carried by the base does not exceed 8% of the load carried by each pile with different diameters.This low percentage ascertains that the piles embedded in cohesive soils carry most of the load throughout their shafts.     

Green synthesis of stable silver nanoparticles by the main reduction component of green tea (Camellia sinensis L.)

Recently the use of medicinal plants potential in the production of nanoparticles has received serious attention. Here, the main component of Camellia sinensis L. (green tea) extract was detected by spectroscopy and the optimal conditions were determined for their performance in green synthesis of silver nanoparticles at room temperature. Epigallocatechin gallate was identified as the dominant component in the extract as determined by spectroscopy, and it was established that its oxidation was a function of the solution pH. Transmission electron microscopy, dynamic light scattering, and visible absorption spectroscopy (UV‐Vis) confirmed the reduction in silver ions to silver nanoparticles (Ag NPs). Controlling over Ag NPs shape and narrow size distribution was achieved with 10 ml green tea leaf extract solution and in different reaction pH. Spherical colloidal Ag NPs with well‐defined hydrodynamic diameters (with average hydrodynamic size of 27.9–50.2 nm) were produced. Silver nitrate concentrations used in this study were lower than that of reported in similar works, and synthesis efficiency was also higher. Nanoparticles were perfectly spherical and their uniformity, compared to similar studies, was much higher. These NPs showed higher degree of stability and were aqueously stable for >10 months in dark glasses at 4°C.Inspec keywords: hydrodynamics, nanoparticles, particle size, pH, visible spectra, ultraviolet spectra, reduction (chemical), transmission electron microscopy, silver, microorganisms, nanofabrication, colloids, biomedical materials, nanomedicine, drug delivery systemsOther keywords: transmission electron microscopy, dynamic light scattering, visible absorption spectroscopy, silver ions, narrow size distribution, silver nitrate concentrations, green synthesis, medicinal plants, solution pH, green tea leaf, hydrodynamic size, silver nanoparticles, Camellia sinensis L, drug delivery, reduction component, epigallocatechin gallate, UV‐visible spectra, hydrodynamic diameters, spherical colloidal Ag NPs, temperature 4.0 degC, Ag     

Preparation and properties of electroless Ni–Zn–P alloy films

Electroless deposition of Ni–Zn–P layers was studied on steel electrodes by varying the bath temperature (40–90°C), pH and chemical composition. The deposition parameters were optimized. Alloys containing 70–86 wt % Ni, 6–20 wt % Zn and 6–10 wt % P are obtained at 20 m h^–1 and 85°C. Corrosion measurements were performed in aerated 5% sodium chloride solution, the corrosion potential and current density are, respectively, –0.49 V/SCE and 2.6 A cm^–2.     

A review on pulsed flow in gas-solid fluidized beds and spouted beds: Recent work and future outlook

This paper reviews the application of pulsed flow in fluidized and spouted beds, widely used in various industries. A number of pulsing studies have been performed to improve the performance of these beds, enhance mixing and promote homogeneity. One effective way to increase the efficiency is to pulse the incoming flow, removing inactive or dead zones, thereby preventing agglomeration and settling. Although numerous studies have been carried out on conventional beds, little has been written on pulsed beds, in spite of their proven advantages. The role of pulsations in hydrodynamics, mixing, segregation, heat transfer, drying, and agglomeration are among the topics addressed. Future needs are identified and projected.     

Highly efficient dye-sensitized solar cells: A comparative study with two different system of solvent-free binary room-temperature ionic liquid-based electrolytes

In this work, novel redox electrolytes based on poly (ethylene oxide) (PEO) were prepared using binary ionic liquid 1-methyl-3-propylimidazolium iodide (MPII) with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI) or 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) to reduce the high viscosity of MPII. The addition of low viscosity ionic liquids is to overcome the low mass transportation of redox mediator faced by the single ionic liquid. Therefore, different ratios of ionic liquids were added, and their effect on the electrical properties of the ionic liquid-based gel polymer electrolytes (GPE) was observed. It was confirmed that all the system dominant by ions rather than electron. The binary ionic liquid system containing 37.5 wt.% of BMIMBF₄ showed the highest ionic conductivity of 24.2 mS cm⁻¹. Fourier-transform infrared and X-ray diffraction studies confirmed that complexation occurred between all materials. The combination of two alkyl side chain length has enhanced the efficiency of the DSSC with short-circuit current density (J_SC) of 26.81 mA cm⁻¹, open-circuit voltage (V_OC) of 0.67 V, fill factor of 44.5% and photovoltaic conversion efficiency (η) of 7.8%. This work has provided valuable insight for further stability of binary ionic liquid-based GPE compared to single ionic liquid electrolytes.