Ultra-Wideband Technology: Characteristcs, Applications and Challenges

Ultra-wideband (UWB) technology is a wireless communication technology designed for short-range applications. It is characterized by its ability to generate and transmit radio-frequency energy over an extensive frequency range. This paper provides an overview of UWB technology including its definition, two representative schemes and some key characteristics distinguished from other types of communication. Besides, this paper also analyses some widely used applications of UWB technology and highlights some of the challenges associated with implementing UWB in real-world scenarios. Furthermore, this paper expands upon UWB technology to encompass terahertz technology, providing an overview of the current status of terahertz communication, and conducting an analysis of the advantages, challenges, and certain corresponding solutions pertaining to ultra-wideband THz communication

NKG2C+NKG2A− Natural Killer Cells are Associated with a Lower Viral Set Point and may Predict Disease Progression in Individuals with Primary HIV Infection

Natural killer (NK) cells are the first line of defense against pathogens of the immune system and also play an important role in resistance against HIV. The activating receptor NKG2C and the inhibitory receptor NKG2A co-modulate the function of NK cells by recognizing the same ligand, HLA-E. However, the role of NKG2A and NKG2C on viral set point and the prediction of HIV disease progression have been rarely reported. In this study, we determined the expression of NKG2C or NKG2A on the surface of NK cells from 22 individuals with primary HIV infection (PHI) stage and 23 HIV-negative normal control (NC) subjects. The CD4+ T cell count and plasma level of HIV RNA in the infected individuals were longitudinally followed-up for about 720 days. The proportion of NKG2C+NKG2A− NK cells was higher in subjects from the low set point group and was negatively correlated with the viral load. In addition, strong anti-HIV activities were observed in NKG2C+ NK cells from the HIV-positive donors. Furthermore, a proportion of NKG2C+NKG2A− NK cells >35.45%, and a ratio of NKG2C/NKG2A >1.7 were predictive for higher CD4+ T cell counts 720 days after infection. Collectively, the experimental results allow us to draw the conclusion that NKG2C+ NK cells might exert an antiviral effect and that the proportion of NKG2C+NKG2A− NK cells, and the ratio of NKG2C/NKG2A, are potential biomarkers for predicting HIV disease progression

Analysis on the buckling performance of embedded co-cured composite sandwich plates under uniaxial compression condition

The research aims at exploring the buckling behavior of embedded co-cured composite sandwich structure (ECCSS) under static load. In accordance with the research objective, an analytical model, which is based on the interlayer stress continuous theory to formulate governing differential equations for predicting the critical buckling loads of ECCSS, has been established. The theoretical solution that satisfies the boundary conditions is obtained using the principle of minimum potential energy. The results obtained by ANSYS software have been used to corroborate the correctness of the analytical model. In addition, effects of various structural parameters (such as ply angles and skin-to-core thickness ratio) on buckling behavior of ECCSS have been investigated

Low latency IP mobility management: protocol and analysis

Abstract Mobile IP is one of the dominating protocols that enable a mobile node to remain reachable while moving around in the Internet. However, it suffers from long handoff latency and route inefficiency. In this article, we present a novel distributed mobility management architecture, ADA (Asymmetric Double-Agents), which introduces double mobility agents to serve one end-to-end communication. One mobility agent is located close to the MN and the other close to the CN. ADA can achieve both low handoff latency and low transmission latency, which is crucial for improvement of user perceived QoS. It also provides an easy-to-use mechanism for MNs to manage and control each traffic session with a different policy and provide specific QoS support. We apply ADA to MIPv6 communications and present a detailed protocol design. Subsequently, we propose an analytical framework for systematic and thorough performance evaluation of mobile IP-based mobility management protocols. Equipped with this model, we analyze the handoff latency, single interaction delay and total time cost under the bidirectional tunneling mode and the route optimization mode for MIPv6, HMIPv6, CNLP, and ADA. Through both quantitative analysis and NS2-based simulations, we show that ADA significantly outperforms the existing mobility management protocols.</p

Water absorption rates and mechanical properties of material extrusion-printed continuous carbon fiber-reinforced nylon composites

Material extrusion (ME) is considered as an effective and economic method to process continuous carbon fiber (CCF)-reinforced polymer composites with complicated structures. In this investigation, water absorption tests and tensile tests were conducted on ME-printed CCF-reinforced polymer composites under hydrothermal conditions. The purpose is to meet the growing need of CCF-reinforced polymer composites for high-humidity and high-heat aerospace applications. In order to achieve optimal comprehensive performance, both the L16 (45) orthogonal array method and the fuzzy reasoning algorithm were employed to carry out multi-objective optimization of four selected input variables, including layup angle, nozzle temperature, fiber filling density, and layer thickness. Experimental results show that the comprehensive performance of composites obtained by inputting data into the fuzzy reasoning system was greater than that obtained from orthogonal test results. Specifically, the optimized input variables are 0° layup angle, 260 °C nozzle temperature, 80% fiber filling rate, and 0.6 mm layer thickness

Quantitative determination of zidovudine diaryl phosphate triester pro-drugs in rat plasma by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry

A rapid, simple, and sensitive high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method was developed and validated for quantitative analysis of 3'-azido-3'-deoxythyrmidine (zidovudine, AZT) diaryl phosphate triester pro-drugs, in rat plasma using 2',3'-dideoxy-2'3'-didehydrothymidine (d4T) as internal standard (IS). The analytes were extracted from rat plasma with methanol after protein precipitation. The compounds were separated by HPLC with gradient elution (on a Shim-pack VP-ODS C-18 analytical column using a mobile phase of methanol/10 mM ammonium acetate). All the analytes were detected in positive ion mode using multiple reaction monitoring (MRM). The method was validated and the specificity, linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries and stability were determined. LLOQs were 10 ng mL(-1) for M1, M2, M3, M4. and M5, respectively. Cori-elation coefficient (r)values for the linear range of 10-10,000 ng mL(-1) were greater than 0.999 for all the analytes. The intra-day and inter-day precision and accuracy were higher than 7.13%. The relative and absolute recovery was above 72% and no matrix effects were observed for all the analytes. This validated method provides a modern, rapid, and robust procedure for the pharmacokinetic studies of the pro-drugs after intravenous administration to rats. Some important results of AZT diaryl phosphate triester pro-drugs concerning chemical effect on pharmacokinetic performance are also studied. (C) 2008 Elsevier B.V. All rights reserved.Major Program of National Natural Science Foundation of China [20732004]; People's Republic of China [2006DFA43030