Light-activated nanotube-porphyrin conjugates as effective antiviral agents

Porphyrins have been used for photodynamic therapy (PDT) against a wide range of targets like bacteria, viruses and tumor cells. In this work, we report porphyrin-conjugated multi-walled carbon nanotubes (NT-P) as potent antiviral agents. Specifically, we used Protoporphyrin IX (PPIX), which we attached to acid-functionalized multi-walled carbon nanotubes (MWNTs). We decided to use carbon nanotubes as scaffolds because of their ease of recovery from a solution through filtration. In the presence of visible light, NT-P was found to significantly reduce the ability of Influenza A virus to infect mammalian cells. NT-P may be used effectively against influenza viruses with little or no chance of them developing resistance to the treatment. Furthermore, NT-P can be easily recovered through filtration which offers a facile strategy to reuse the active porphyrin moiety to its fullest extent. Thus NT-P conjugates represent a new approach for preparing ex?vivo reusable antiviral agents.     

Analysis and Development of Ka- and Q-Band Waveguide Impedance Standards

This paper reports the salient design features and performance analysis of a precision waveguide, standard mismatches of voltage standing wave ratios (VSWRs) 1.10, 1.20 and 1.30 at Ka-band frequencies. Also standard waveguide sections and flush shorts are developed at Ka-band and Q-band and these are analyzed based on their physical dimensions, respectively. The performances of precision waveguide and standard mismatches are observed based on their dimensions and compared with measured values using slotted line technique at Ka-band. The calibration results of mismatch set are found with good agreement for their designated VSWRs with expanded uncertainties <0.03 and their traceability is established through the precision waveguide. These standards will serve as transfer standards of impedance at Ka-band and Q-band ranges and to assign the accuracy of impedance measuring instruments.     

EasyPLL简化先进锁相环路的设计过程

引言电脑辅助设计工具不但可以大幅缩短锁相环路的设计时间,还可改善电路设计。通过电脑辅助设计工具,工程师可以更深入地了解设计背后的运作原理。若实际性能与理论预测相符,工程师对整个设计会更具信心。若理论模型预测的性能高于实际性能,问题很可能出在元件本身,例如元件过     

On the optimality of conditional expectation as a Bregman predictor

We consider the problem of predicting a random variable X from observations, denoted by a random variable Z. It is well known that the conditional expectation E[X|Z] is the optimal L/sup 2/ predictor (also known as "the least-mean-square error" predictor) of X, among all (Borel measurable) functions of Z. In this orrespondence, we provide necessary and sufficient conditions for the general loss functions under which the conditional expectation is the unique optimal predictor. We show that E[X|Z] is the optimal predictor for all Bregman loss functions (BLFs), of which the L/sup 2/ loss function is a special case. Moreover, under mild conditions, we show that the BLFs are exhaustive, i.e., if for every random variable X, the infimum of E[F(X,y)] over all constants y is attained by the expectation E[X], then F is a BLF.     

Monte Carlo study of Germanium n- and pMOSFETs

In this paper, we perform fullband Monte Carlo simulations of Ge bulk nand pMOSFETs and compare them with their Si counterparts. We consider transport in the presence of phonon, ionized impurity, surface roughness scattering, and impact ionization. Quantum confinement in the inversion layer is taken into account in the form of a modified potential. Germanium devices gave higher drive current when compared with Si devices for the device structures studied. Consistent with the arguments of Lundstrom, the performance enhancement of Ge MOSFETs lies between that which would be expected based on the higher mobility alone, and the much smaller advantage, if any, offered in the ballistic limit where transport is governed by thermal injection velocities from the source.     

GAS-NON-NEWTONIAN LIQUID FLOW THROUGH ELBOWS

Experimental investigations have been carried out to evaluate the two-phase pressure drop across different types of elbows in the horizontal plane for gas-non-Newtonian pseudoplastic liquid flow. A generalised correlation have been developed to predict The two-phase pressure drop as a function of various physical and dynamic variables of the system. Statistical analysis of the correlation suggests that the correlation is of acceptable accuracy.     

Study of thin film multilayers using X-ray reflectivity and scanning probe microscopy

We have presented new schemes to analyse grazing incidence specular X-ray reflectivity data to obtain structural and chemical information of thin films. Analysis of specular reflectivity data gives information along the depth of the film, whereas, analysis of non-specular data reveals the structural information across the film surface and interfaces. The schemes proposed are based on the Born approximation and the distorted wave born approximation (DWBA). Surface structural parameters such as, height–height correlation and roughness exponent of the film obtained from the analysis of X-ray reflectivity was compared with results obtained from atomic force microscopy     

Stability Analysis of the Continuous-Conduction-Mode Buck Converter Via Filippov's Method

To study the stability of a nominal cyclic steady state in power electronic converters, it is necessary to obtain a linearization around the periodic orbit. In many past studies, this was achieved by explicitly deriving the Poincare map that describes the evolution of the state from one clock instant to the next and then locally linearizing the map at the fixed point. However, in many converters, the map cannot be derived in closed form, and therefore this approach cannot directly be applied. Alternatively, the orbital stability can be worked out by studying the evolution of perturbations about a nominal periodic orbit, and some studies along this line have also been reported. In this paper, we show that Filippov's method - which has commonly been applied to mechanical switching systems - can be used fruitfully in power electronic circuits to achieve the same end by describing the behavior of the system during the switchings. By combining this and the Floquet theory, it is possible to describe the stability of power electronic converters. We demonstrate the method using the example of a voltage-mode-controlled buck converter operating in continuous conduction mode. We find that the stability of a converter is strongly dependent upon the so-called saltation matrix - the state transition matrix relating the state just after the switching to that just before. We show that the Filippov approach, especially the structure of the saltation matrix, offers some additional insights on issues related to the stability of the orbit, like the recent observation that coupling with spurious signals coming from the environment causes intermittent subharmonic windows. Based on this approach, we also propose a new controller that can significantly extend the parameter range for nominal period-1 operation.     

Construction of turbo code interleaves from 3-regular Hamiltonian graphs

In this letter, we present a new construction of interleavers for turbo codes from 3-regular Hamiltonian graphs. The interleavers can be generated using a few parameters, which can be selected in such a way that the girth of the interleaver graph (IG) becomes large, inducing a high summary distance. The size of the search space for these parameters is derived. The proposed interleavers themselves work as their de-interleavers.     

Lowering of thickness of boron-doped microcrystalline hydrogenated silicon film by seeding technique

By using a seeding technique it has been possible to reduce the thickness of p-μc-Si:H film to 230 Å, with an improved electrical conductivity (0.93 S cm⁻¹) and lower optical absorption compared to those of conventional p-μc-Si:H layers without a seed layer, for use at the tunnel junction and as the top layer of a double junction n–i–p structured a-Si solar cell. Undoped-μc-Si:H has been used as the seed layer. The layers were prepared by the radio frequency plasma-enhanced chemical vapour deposition (RF-PECVD) method (13.56 MHz) at 40 mW/cm² rf power density and low substrate temperature (200 °C). The ultrathin seed layer (30 Å) enhances the growth of microcrystallinity of the p-type μc-Si:H film as confirmed by the results of transmission electron microscopy (TEM) analysis and Raman spectroscopy.