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Parasitic nematodes are important and abundant parasites adapted to live a parasitic lifestyle, with these adaptations all aimed at facilitating their survival and reproduction in their hosts. The recently sequenced genomes of four Strongyloides species, gastrointestinal parasites of humans and other animals, alongside transcriptomic and proteomic analysis of free-living and parasitic stages of their life cycles have revealed a number of protein families with a putative role in their parasitism. Many of these protein families have also been associated with parasitism in other parasitic nematode species, suggesting that these proteins may play a fundamental role in nematode parasitism more generally. Here, we review key protein families that have a putative role in Strongyloides’ parasitism – acetylcholinesterases, astacins, aspartic proteases, prolyl oligopeptidases, proteinase inhibitors (trypsin inhibitors and cystatins), SCP/TAPS and transthyretin-like proteins – and the evidence for their key, yet diverse, roles in the parasitic lifestyle.
Recently, compact and high-resolution camera modules with auto-focusing (AF) function have been integrated into cell phones in order to capture sharp photographs. Consumer demands AF camera modules in cell phones to have high performance with low cost. Accordingly, the present study proposes a new electromagnetic design of miniature AF voice coil motor (VCM) actuator with closed-loop control for cell phone camera modules to satisfy the requirements. The structure of the proposed AF VCM actuators was designed by using simulation methods. The performance of the proposed AF VCM actuators was demonstrated by a laboratory-built prototype. The experimental results have shown that the proposed AF VCM actuator has excellent performance with lower power consumption, higher positioning repeatability, and lower cost, when compared to previous AF VCM actuators with open-loop control or closed-loop control.
Concentration of a diffusing substance in a medium was derived in various cases of uni-dimensional diffusion, including in a semi-infinite medium and a plate-shaped medium. Multi-dimensional diffusion involves boundary conditions in each coordinate direction. The algorithm dealing with uni-dimensional case becomes very complicated in multi-dimensional cases. This study proposes an algorithm, which is called the complementary method, that combines complementary functions of the normalized solution in uni-dimensional diffusion case by multiplication to solve those in various multi-dimensional diffusion cases with dramatically simplified mathematics. Besides, the complementary method is used to solve various kinds of boundary conditions for multi-dimensional diffusion.
The notion of inside dynamics of traveling waves has been introduced in the recent paper
. Assuming that a traveling wave
u(t,x) = U(x − ct)
is made of several components υi ≥ 0
(i ∈ I ⊂ N), the inside dynamics of the wave is then
given by the spatio-temporal evolution of the densities of the components
υi. For reaction-diffusion equations of the
∂tu(t,x) = ∂xxu(t,x) + f(u(t,x)),
where f is of monostable or bistable type, the results in  show that traveling waves can be classified into
two main classes: pulled waves and pushed waves. Using the same framework, we study the
pulled/pushed nature of the traveling wave solutions of delay equations
∂tu(t,x) = ∂xxu(t,x) + F(u(t −τ,x),u(t,x))
We begin with a
review of the latest results on the existence of traveling wave solutions of such
equations, for several classical reaction terms. Then, we give analytical and numerical
results which describe the inside dynamics of these waves. From a point of view of
population ecology, our study shows that the existence of a non-reproductive and
motionless juvenile stage can slightly enhance the genetic diversity of a species
colonizing an empty environment.
We carried out a computational study of propagation speeds of
reaction-diffusion-advection fronts in three dimensional (3D) cellular and
Arnold-Beltrami-Childress (ABC) flows with Kolmogorov-Petrovsky-Piskunov(KPP)
nonlinearity. The variational principle of front speeds reduces the problem to a principal
eigenvalue calculation. An adaptive streamline diffusion finite element method is used in
the advection dominated regime. Numerical results showed that the front speeds are
enhanced in cellular flows according to sublinear power law
p ≈ 0.13, δ the flow intensity. In ABC flows however,
the enhancement is O(δ) which can be attributed to the
presence of principal vortex tubes in the streamlines. Poincaré sections are used to
visualize and quantify the chaotic fractions of ABC flows in the phase space. The effect
of chaotic streamlines of ABC flows on front speeds is studied by varying the three
parameters (a,b,c) of the ABC flows. Speed enhancement along
x direction is reduced as b (the parameter controling
the flow variation along x) increases at fixed
(a,c) > 0, more rapidly as the corresponding ABC streamlines become
In this study, a novel procedure has been developed for predicting the notched strengths of composite plates each with a center hole. In this approach, the stress distribution of a composite plate with a center hole is first obtained by a finite element analysis, in which the experimental notched strength is applied at the boundary of the finite element model. Secondly, the point stress criterion (PSC) is used to find the characteristic length for each plate with different size of hole by an interpolation of the finite element analysis results. The characteristic length is then expressed as an empirical function of the hole size as well as the width of the plate. Finally, the notched strengths of composite plates are predicted based on the empirical function and the finite element analysis results incorporated with the principle of superposition in elasticity. For validation, three different cases from the literatures are adopted for comparison. It is shown that the predicted notched strengths by this new methodology agree well with both the experimental results and the results from analytical solutions based PSC.
Over the past decade, the PV industry has witnessed tremendous growth in manufacturing scale and technology advancement, with PV generated electricity cost ever approaching grid parity. Among them, Si based thin film technology has made substantial progress in demonstrating its inherent advantages in lower material cost, ease of manufacturing and higher energy yield, etc. More recently, reduced product prices and competing technologies from crystalline silicon and other thin film technologies have made amorphous and microcrystalline silicon based thin film technology very challenging, and requires further increase in module efficiency and decrease in manufacturing cost. As one of the few companies in the world with significant manufacturing capacity for tandem thin film Si PV products, Chint Solar (Astronergy) has been at the forefront of technology development for the mass production of large-scale (Gen. 5, 1.43m2) Si thin film solar modules in the last 5 years. We will review major technology advancements which have been mass production proven and led to the mass produced tandem silicon thin film module with 10.0% plus stabilized efficiency, along with the field performance of those modules.
We report on a direct measurement of electrical potential and field profiles across the n-i-p junction of hydrogenated nanocrystalline silicon (nc-Si:H) solar cells, using the nanometer-resolution potential imaging technique of scanning Kelvin probe force microscopy (SKPFM). It was observed that the electric field is nonuniform across the i layer. It is much higher in the p/i region than in the middle and the n/i region, illustrating that the i layer is actually slightly n-type. A measurement on a nc-Si:H cell with a higher oxygen impurity concentration shows that the nonuniformity of the electric field is much more pronounced than in samples having a lower O impurity, indicating that O is an electron donor in nc-Si:H materials. This nonuniform distribution of electric field implies a mixture of diffusion and drift of carrier transport in the nc-Si:H solar cells. The composition and structure of these nc-Si:H cells were further investigated by using secondary-ion mass spectrometry and Raman spectroscopy, respectively. The effects of impurity and structural properties on the electrical potential distribution and solar cell performance are discussed.
A solution based on an advancing model for the content of diffusion material in a cube of medium is derived. The cube is assumed to be surrounded by diffusion material, and the diffusion material penetrates through all six surfaces and diffuses toward the center of the cube. The model accounts for the interaction between the diffusions in the three principle coordinates of the Cartesian coordinate system. For the first time, an exact solution of the content of the diffusion material based on the advancing model is derived in a clean form for a three-dimensional case.
In this study, the mechanical properties of graphene and single walled carbon nanotubes (SWCNTs) were investigated based on molecular dynamics (MD) simulation. During the characterization of the mechanical properties, the atomistic interactions of the carbon atoms were described using the bonded and non-bonded energies. The bonded energy consists of four different interactions: Bond stretching, bond angle bending, dihedral angle torsion, and inversion. On the other hand, the non-bonded interaction between the carbon atoms within the cut-off ranges was regarded as the van der Waals (vdW) force. The effect of vdW force on the mechanical properties of graphene and SWCNTs would be mainly of concern. Simulation results indicated that the Young's modulus of the graphene with vdW force included is 15% higher than that without considering any vdW interaction. The same tendency also was observed in the armchair and zig-zag SWCNTs. Furthermore, it was revealed that the increment of moduli caused by the vdW force could be primarily attributed to the 1-4 vdW interaction. The influence of the vdW interactions on the mechanical properties of graphene and SWCNTs was then elucidated using the parallel spring concept.
Rose geranium (Pelargonium graveolens, Geraniaceae) has anti-cancer and anti-inflammatory properties, and promotes wound healing. Similarly, Ganoderma tsugae (Ganodermataceae), Codonopsis pilosula (Campanulaceae) and Angelica sinensis (Apiaceae) are traditional Chinese herbs associated with immunomodulatory functions. In the present study, a randomised, double-blind, placebo-controlled study was conducted to examine whether the Chinese medicinal herb complex, RG-CMH, which represents a mixture of rose geranium and extracts of G. tsugae, C. pilosula and A. sinensis, can improve the immune cell count of cancer patients receiving chemotherapy and/or radiotherapy to prevent leucopenia and immune impairment that usually occurs during cancer therapy. A total of fifty-eight breast cancer patients who received chemotherapy or radiotherapy were enrolled. Immune cell levels in patient serum were determined before, and following, 6 weeks of cancer treatment for patients receiving either an RG-CMH or a placebo. Administration of RG-CMH was associated with a significant reduction in levels of leucocytes from 31·5 % for the placebo group to 13·4 % for the RG-CMH group. Similarly, levels of neutrophils significantly decreased from 35·6 % for the placebo group to 11·0 % for the RG-CMH group. RG-CMH intervention was also associated with a decrease in levels of T cells, helper T cells, cytotoxic T cells and natural killer cells compared with the placebo group. However, these differences between the two groups were not statistically significant. In conclusion, administration of RG-CMH to patients receiving chemotherapy/radiotherapy may have the capacity to delay, or ease, the reduction in levels of leucocytes and neutrophils that are experienced by patients during cancer treatment.
Amorphous, polycrystalline, and single crystal nanometer dimension particles can be formed in a variety of substrates by ion implantation and subsequent annealing. Such composite colloidal materials exhibit unique optical properties that could be useful in optical devices, switches, and waveguides. However colloids formed by blanket implantation are not uniform in size due to the nonuniform density of the implant, resulting in diminution of the size dependent optical properties. The object of the present work is to form more uniform size particles arranged in a 2-dimensional lattice by using a finely focused ion beam to implant identical ion doses only into nanometer size regions located at each point of a rectangular lattice. Initial work is being done with a 30 keV Ga beam implanted into Si. Results of particle formation as a function of implant conditions as analyzed by Rutherford backscattering, x-ray analysis, atomic force microscopy, and both scanning and transmission electron microscopy will be presented and discussed.
Low-temperature crystallization of a-Si is important for display and Silicon-On- Insulator (SOT) technologies. We present optical characterization (Raman scattering and photoluminescence) of H2 and O2 plasma enhanced crystallization of a-Si:H films. H2 plasma treatment is shown to be the most efficient, leading to larger grain sizes, and both H2 and O2 plasma lead to visible photoluminescence (PL). Recently, the PL of re-crystallized a-Si films has been explained in terms of quantum confinement . The mean size of the crystallites in our re-crystallized films is determined by Raman scattering for different treatments parameters. No correlation between size and the photon energy of the visible emission is found. However, we can clearly distinguish between the PL from purely amorphous and re-crystallized a-Si:H films: Their PL temperature dependence and spectra are very different. The origin of the visible PL in re-crystallized thin Si films is discussed.
We have deposited thin B- and P-doped Si layers by electron cyclotron resonance CVD on c- Si (4 Ωcm, CZ) and on quartz glass substrates at T=325°C. Films grown on quartz glass are of microcrystalline nature with crystalline volume fractions of about 70 % and a resistivity ranging from 0.01 - 10 (Ωcm)−1 depending on doping concentration. The doping efficiency is close to unity with the carrier mobility being independent of doping concentration for both B- and Pdoping. Films grown on c-Si, on the other hand, exhibit perfect homoepitaxial morphology when the gas phase doping concentration exceeds 1000 ppm and 5000 ppm for P- and B-doping, respectively. The quality of the films is tested by preparing thin film emitter solar cells. We find efficiencies above 11 % for cells without ARC. The result are compared to cells with diffused emitters, otherwise prepared with the same technological steps.
New possibilities for modifying the phonon spectra of III-V compounds are evidenced by micro-Raman analysis of porous layers prepared by electrochemical anodization of (111 )Aoriented n-GaP substrates. In particular, a surface-related vibrational mode along with a porosity-induced decoupling between the longitudinal optical (LO) phonon and plasmon are observed. We prove that filling in the pores with other materials (aniline as a first approach) is a promising tool for controlling the surface phonon frequency.
Ion implantation is a versatile technique by which compound semiconductor nanocrystals may be synthesized in a wide variety of host materials. The component elements that form the compound of interest are implanted sequentially into the host, and nanocrystalline precipitates then form during thermal annealing. Using this technique, we have synthesized compound semiconductor nanocrystal precipitates of ZnS, CdS, PbS, and CdSe in a fused silica matrix. The resulting microstructures and size distributions were investigated by cross-sectional transmission electron microscopy. Several unusual microstructures were observed, including a band of relatively large nanocrystals at the end of the implant profile for ZnS and CdSe, polycrystalline agglomerates of a new phase such as γ-Zn 2SiO4, and the formation of central voids inside CdS nanocrystals. While each of these microstructures is of fundamental interest, such structures are generally not desirable for potential device applications for which a uniform, monodispersed array of nanocrystals is required. Methods were investigated by which these unusual microstructures could be eliminated.
We report a principle that allows writing visible light emitting semiconductor patterns of arbitrary shape down to the sub-micrometer scale. We demonstrate that porous semiconductor growth can be electrochemically initiated preferentially at surface defects created in an n-type substrate by Si++ focused ion beam bombardment. For n-type material in the dark, the electrochemical pore formation potential (Schottky barrier breakdown voltage) is significantly lower at the implanted locations than for an unimplanted surface. This difference in the threshold voltages is exploited to achieve the selectivity of the pore formation process. Visible light emitting patterns of porous Si and GaAs have been created in this way. At present, the size of the structures is limited only by the diameter of the writing ion beam, and pattern diameters in the 50–200-nm range are possible.
The use of nanoparticle precursors for electronic materials including sulfides, selenides, oxides and the elements has potentially wide ranging implications for improving device properties and substantially reducing the deposition costs. To realize this goal the complex interfacial chemistry of these small particles must be controlled. In this paper we present a number of cases demonstrating the complexity of this chemistry. These include CuInSe2 where the kinetics of phase formation dominate the sintering process; CdTe where sintering proceeds with and without the sintering enhancement of CdCl2, but produces materials different electronically than bulk materials; and the use of compound and elemental nanoparticles ( Ag, Al, Hg-Cu-Te and Sb-Te) for contacts to elemental and compound semiconductors (Si and CdTe).