浅谈IMS和PSTN/CS网络的互通

IP多媒体子系统自从3GPP UMTS Release5后已经被加入到通用移动通信系统(UMTS)的核心网络中.现在,UMTS网络主要包含以下3个域:电路交换(CS)、分组交换(PS)和IP多媒体子系统(IMS).IMS需要同原有相对陈旧的网络电路交换(CS)网络及公用电话交换网(PSTN).本文主要针对IMS同PSTN/CS网络的互通进行了概述.     

硅基碲镉汞红外探测器表面钝化研究

碲镉汞(Mercury Cadmium Telluride, MCT)材料的表面钝化是红外探测器制备中的关键工艺之一。高性能MCT器件需要稳定且可重复生产的钝化表面和符合器件性能要求的界面。因此,探究MCT表面钝化技术具有重要意义。研究了MCT的分子束外延(Molecular Beam Epitaxy, MBE)原位钝化与磁控溅射钝化两种钝化技术。结果表明,MBE原位钝化膜层的致密性较好,钝化层表面的缺陷孔洞较小,钝化层与MCT的晶格匹配度较好,器件流片的电流-电压(I-V)特性要优于磁控溅射正常钝化。     

Bacteria-Responsive Self-Assembly of Antimicrobial Peptide Nanonets for Trap-and-Kill of Antibiotic-Resistant Strains

Bacterial trapping using nanonets is a ubiquitous immune defense mechanism against infectious microbes. These nanonets can entrap microbial cells, effectively arresting their dissemination and rendering them more vulnerable to locally secreted microbicides. Inspired by this evolutionarily conserved anti-infective strategy, a series of 15 to 16 residue-long synthetic β-hairpin peptides is herein constructed with the ability to self-assemble into nanonets in response to the presence of bacteria, enabling spatiotemporal control over microbial killing. Using amyloid-specific K114 assay and confocal microscopy, the membrane components lipoteichoic acid and lipopolysaccharide are shown to play a major role in determining the amyloid-nucleating capacity as triggered by Gram-positive and Gram-negative bacteria respectively. These nanonets displayed both trapping and killing functionalities, hence offering a direct improvement from the trap-only biomimetics in literature. By substituting a single turn residue of the non-amyloidogenic BTT1 peptide, the nanonet-forming BTT1-3A analog is produced with comparable antimicrobial potency. With the same sequence manipulation approach, BTT2-4A analog modified from BTT2 peptide showed improved antimicrobial potency against colistin-resistant clinical isolates. The peptide nanonets also demonstrated robust stability against proteolytic degradation, and promising in vivo efficacy and biosafety profile. Overall, these bacteria-responsive peptide nanonets are promising clinical anti-infective alternatives for circumventing antibiotic resistance.     

A NIR-II AIEgen-Based Supramolecular Nanodot for Peroxynitrite-Potentiated Mild-Temperature Photothermal Therapy of Hepatocellular Carcinoma

Compared to conventional photothermal therapy (PTT) which requires hyperthermia higher than 50 °C, mild-temperature PTT is a more promising antitumor strategy with much lower phototoxicity to neighboring normal tissues. However, the therapeutic efficacy of mild-temperature PTT is always restricted by the thermoresistance of cancer cells. To address this issue, a supramolecular drug nanocarrier is fabricated to co-deliver nitric oxide (NO) and photothermal agent DCTBT with NIR-II aggregation-induced emission (AIE) characteristic for mild-temperature PTT. NO can be effectively released from the nanocarriers in intracellular reductive environment and DCTBT is capable of simultaneously producing reactive oxygen species (ROS) and hyperthermia upon 808 nm laser irradiation. The generated ROS can further react with NO to produce peroxynitrite (ONOOˉ) bearing strong oxidization and nitration capability. ONOOˉ can inhibit the expression of heat shock proteins (HSP) to reduce the thermoresistance of cancer cells, which is necessary to achieve excellent therapeutic efficacy of DCTBT-based PTT at mild temperature (<50 °C). The antitumor performance of ONOOˉ-potentiated mild-temperature PTT is validated on subcutaneous and orthotopic hepatocellular carcinoma (HCC) models. This research puts forward an innovative strategy to overcome thermoresistance for mild-temperature PTT, which provides new inspirations to explore ONOOˉ-sensitized tumor therapy strategies.     

二氧化铪材料中Cu的最佳迁移路径

The movement of Cu in a HfO2-based resistive random access memory （RRAM） device is investigated in depth by first-principle calculations. Thermodynamics analysis shows that the dominant motion of Cu tends to be along the [001] orientation with a faster speed. The migration barriers along different routes are compared and reveal that the [001] orientation is the optimal migration route of Cu in HfO2, which is more favorable for Cu transportation. Furthermore, the preferable HfOz growth orientation along [100], corresponding to Cu migration along [001], is also observed. Therefore, it is proposed that the HfO2 material should grow along [100] and the operating voltage should be applied along [001], which will contribute to the improvement of the response speed and the reduction of power consumption of RRAM.     

Average SER Performance of Distributed Antenna Systems Over Shadowed Generalized-Gamma Channels for Different Modulation Schemes

Recently, much attention has been drawn to distributed antenna systems (DAS), which are proposed to improve the performance of mobile communication systems. This paper focuses on the analysis of the average symbol error rate (SER) of DAS over a generic composite channel. Initially, a new composite channel model is considered for DAS, which is a mixture of path loss, lognormal shadowing and generalized-Gamma fast fading. This composite channel model is a generic model, which includes many well-known composite channel models as special cases. Based on the channel model, the cumulative distribution function of the output signal-to-noise ratio is obtained by employing selective transmission scheme. Moreover, by averaging the channel conditions and the positions of the MS in the cell, an approximate expression of the average SER is derived, which is a unified form of expression for many commonly used modulation schemes. Numerical results show that the derived expression of the average SER can provide sufficient precision for evaluating the SER performance of DAS under different modulation schemes.     

Electrocatalysis of Fe-N-C Bonds Driving Reliable Interphase and Fast Kinetics for Phosphorus Anode in Sodium-Ion Batteries

Phosphorus exhibits high capacity and low redox potential, making it a promising anode material for future sodium-ion batteries. However, its practical applications are confined by poor durability and sluggish kinetics. Herein, an innovative in-situ electrochemically self-driven strategy is presented to embed phosphorus nanocrystal (≈10 nm) into a Fe-N-C-rich 3D carbon framework (P/Fe-N-C). This strategy enables rapid and high-capacity sodium ion storage. Through a combination of experimental assistance and theoretical calculations, a novel synergistic catalytic mechanism of Fe-N-C is reasonably proposed. In detail, the electrochemical formation of Fe-N-C catalytic sites facilitates the release of fluorine in ester-based electrolyte, inducing Na⁺-conducting-enhanced solid-electrolyte interphase. Furthermore, it also effectively induces the dissociation energy of the P-P bond and promotes the reaction kinetics of P anode. As a result, the unconventional P/Fe-N-C anode demonstrates outstanding rate-capability (267 mAh g⁻¹ at 100 A g⁻¹) and cycling stability (72%, 10 000 cycles). Notably, the assembled pouch cell achieves high-energy density of 220 Wh kg⁻¹.     

BPA-Containing Polydopamine Nanoparticles for Boron Neutron Capture Therapy in a U87 Glioma Orthotopic Model

Boron neutron capture therapy (BNCT) is a promising therapy for refractory cancer based on the cytotoxic reaction of ¹⁰B (n, α) ⁷Li. Although two BNCT agents are clinically available, they are quickly metabolized and show modest enrichment in tumor sites, partially limiting BNCT widespread application. Consequently, novel agents that perform active targeting and show good biocompatibility have to be developed. Herein, boronophenylalanine-containing polydopamine (B-PDA) nanoparticles are easily fabricated by encapsulating boronophenylalanine (BPA) in polydopamine via nitrogen-boronate coordination. In this study, B-PDA achieves increased tumor accumulation and prolonged retention effects in the tumor site and superior antitumor activity post neutron irradiation in the orthotopic xenograft glioma model. In brief, this study offers a novel strategy for BPA delivery and may broaden the perspective on nanomedicine design for BNCT.     

Magnesium Gradient-Based Hierarchical Scaffold for Dual-Lineage Regeneration of Osteochondral Defect

Osteochondral regeneration remains a great challenge due to the limited self-healing ability and the complexity of its hierarchical structure and composition. Mg²⁺ and hypoxia are two effective modulators in boosting chondrogenesis. To this end, a double-layered scaffold (D) consisting of a hydrogel layer on a porous cryogel is fabricated to mimic the hierarchical structure of osteochondral tissue. An Mg²⁺ gradient is incorporated into the double-layered scaffold with hypoxia-mimicking deferoxamine (DFO) embedded in the hydrogel (D-Mg-DFO), which remarkably augments the dual-lineage regeneration of both cartilage and subchondral bone. The higher Mg²⁺ supplementation from the upper hydrogel, associated with its hypoxia-mimicking situation and small pore size, exhibits promotive effects on chondrogenic differentiation. The lower Mg²⁺ supplementation from the bottom cryogel, associated with its interconnected macroporous structure, achieves multiple contributions in stem cell migration from bone marrow cavity, matrix mineralization, and osteogenesis. Furthermore, rabbits’ trochlea osteochondral defects are established to evaluate the regenerative outcome. Compared to control scaffolds containing only Mg²⁺ or DFO, the D-Mg-DFO scaffold presents the best regenerative effect under the synergistic contribution of multiple factors. Overall, this work provides a new design of scaffold toward an effective repair of cartilage defect.     

一种单材料双功函数栅MOSFET解析模型

An analytical surface potential model for the single material double work function gate(SMDWG) MOSFET is developed based on the exact resultant solution of the two-dimensional Poisson equation. The model includes the effects of drain biases, gate oxide thickness, different combinations of S-gate and D-gate length and values of substrate doping concentration. More attention has been paid to seeking to explain the attributes of the SMDWG MOSFET, such as suppressing drain-induced barrier lowering(DIBL), accelerating carrier drift velocity and device speed. The model is verified by comparison to the simulated results using the device simulator MEDICI. The accuracy of the results obtained using our analytical model is verified using numerical simulations. The model not only offers the physical insight into device physics but also provides the basic designing guideline for the device.