Convective Initiation by Topographically Induced Convergence Forcing over the Dabie Mountains on 24 June 2010

The initiation of convective cells in the late morning of 24 June 2010 along the eastward extending ridge of the Dabie Mountains in the Anhui region, China, is studied through numerical simulations that include local data assimilation. A primary convergence line is found over the ridge of the Dabie Mountains, and along the ridge line several locally enhanced convergence centers preferentially initiate convection. Three processes responsible for creating the overall convergence pattern are identified. First, thermally-driven upslope winds induce convergence zones over the main mountain peaks along the ridge, which are shifted slightly downwind in location by the moderate low-level easterly flow found on the north side of a Mei-yu front. Second, flows around the main mountain peaks along the ridge create further convergence on the lee side of the peaks. Third, upslope winds develop along the roughly north-south oriented valleys on both sides of the ridge due to thermal and dynamic channeling effects, and create additional convergence between the peaks along the ridge. The superposition of the above convergence features creates the primary convergence line along the ridge line of the Dabie Mountains. Locally enhanced convergence centers on the primary line cause the initiation of the first convection cells along the ridge. These conclusions are supported by two sensitivity experiments in which the environmental wind （dynamic forcing） or radiative and land surface thermal forcing are removed, respectively. Overall, the thermal forcing effects are stronger than dynamic forcing given the relatively weak environmental flow.

A Case Study of the Initiation of Parallel Convective Lines Back-Building from the South Side of a Mei-yu Front over Complex Terrain

Parallel back-building convective lines are often observed extending to the southwest of some mesoscale convective systems(MCSs)embedded in the mei-yu front in China.The convective lines with echo training behavior can quickly develop into a stronger convective group of echoes,resulting in locally heavy rainfall within the mei-yu front rainband.The initiation mechanism of the back-building convective lines is still unclear and is studied based on high-resolution numerical simulation of a case that occurred during 27−28 June 2013.In the present case,the new convection along the convective lines was found to be forced by nonuniform interaction between the cold outflow associated with the mei-yu front MCSs and the warm southerly airflow on the south side of the mei-yu front,which both are modified by local terrain.The mei-yu front MCSs evolved from the western to the eastern side of a basin surrounded by several mesoscale mountains and induced cold outflow centered over the eastern part of the basin.The strong southwest airflow ahead of the mei-yu front passed the Nanling Mountains and impacted the cold outflow within the basin.The nonuniform interaction led to the first stage of parallel convective line formation,in which the low mountains along the boundary of the two airflows enhanced the heterogeneity of their interaction.Subsequently,the convective group quickly developed from the first stage convective lines resulted in apparent precipitation cooling that enhanced the cold outflow and made the cold outflow a sharp southward windshift.The enhanced cold outflow pushed the warm southerly airflow southward and impacted the mountains on the southeast side of the basin,where the roughly parallel mountain valleys or gaps play a controlling role in a second stage formation of parallel convective lines.

γ⁃Fe2O3@carboxymethyl Cellulose as Potential Oral Nanomedicine for Iron Deficiency Anemia Treatment on Rats

Oral iron supplements such as ferrous iron salts are major treatment agents for iron deficiency anemia(IDA)due to the convenience of large dose administration and good patient compliance.However,the gastrointestinal adverse impact caused by Fe2+stimulus and low bioavailability severely impedes its therapeutic effects.In recent years,it has been found that nano iron⁃based nanoparticles with high surface⁃to⁃volume ratio and low iron ion leakage can alleviate the toxic effect and improve the gastrointestinal absorbance.For further clinical development,nano materials need to meet the pharmaceutical quality demand.Carboxymethyl cellulose(CMC)is a significant pharmaceutical ingredient applied in approved drug formulations,and polyglucosorbitol carboxymethylether(PSC)has been utilized in iron⁃based nanomedicine ferumoxytol synthesis,both of which can be firmly anchored on iron oxide by carboxyl chelation.In this work,iron oxide nanoparticles(NPs)modified with CMC were designed and synthesized,and the structure composition and physicochemical properties were distinctly characterized.Oral supplement effects on rat IDA were investigated and compared with other recently reported iron supplements including NPs modified with PSC.Results show that the oral nano iron supplement achieved the recovery of hemoglobin and serum iron level in only two weeks with high safety.The nano iron oxide modified with pharmaceutical excipients provides new potential approach for oral iron supplement available in clinics.

碳化硅复合镍磷合金涂层的组织结构、显微硬度及腐蚀性能研究

镍基复合涂层是一项有望替代电镀铬涂层的先进绿色环保表面处理技术。本文在铝合金表面制备了纯Ni、NiP及其与SiC复合涂层,利用SEM、EDS和XRD研究了Ni、NiP及其复合涂层的微观形貌、成分与组织结构,利用显微硬度计与电化学工作站研究了其硬度与耐腐蚀性能。研究结果表明:SiC复合电镀纯镍涂层的表面较为粗糙,SiC复合电镀镍磷合金涂层中晶粒轮廓明显;电沉积镍磷合金涂层的相结构包括晶体Ni_(2)P、Ni_(12)P_(5)和非晶NiP。铝合金基体表面Ni-P合金涂层的显微硬度显著高于纯Ni涂层,引入SiC纳米颗粒形成复合涂层可提高其显微硬度;SiC颗粒有助于提高复合涂层在氯化钠溶液中的腐蚀电位,降低腐蚀电流密度,提高其耐蚀性能。

Computer Platform Adaptive Interference Cancellation Using Higher-Order Statistics

Broadband wireless interference in a computer platform is the result of multiple dynamic electromagnetic emission sources. This interference is non-Gaussian and a receiver design based on the Gaussian assumption will yield suboptimal performance. In fact, it has a double-sided K-distribution and needs to be treated differently in the design process. When dealing with this type of interference in the presence of white Gaussian noise, traditional interference/noise cancellation schemes do not produce satisfactory results. In this paper, we present an interference mitigation method which improves BER performance. We do this by using the cross-cumulant as the criterion of goodness. Specifically, our algorithm is based on higher order statistics (HOS) and is designed to reconstruct and to cancel the interference in a recursive fashion. The algorithm is tested on both BPSK and OFDM communication environments. We compare performance in terms of BER against other cancellation methods.

Passive Ubiquitous Perception System Oriented to Aerospace-Ground Internet of Things Communication

Because the aerospace-ground Internet no longer relies on deploying infrastructure such as base stations,it has the advantage of all-weather full coverage services that traditional terrestrial networks do not have.However,the traditional global navigation satellite system does not support communication services.The newly developing aerospace network system is still in the construction stage,and there is no applicable solution yet.Passive communication technology is an important method to solve the contradiction between the low battery capacity of the Internet of things(IoT)node and the high energy consumption of communication.It is the development trend of the IoT.However,the current passive technology based on Wi-Fi and other signals cannot achieve arbitrary communication due to the excitation signal acquisition problem.To solve the above two major problems,this paper proposes a passive system design for aerospace-ground IoT communication.The system can use the global navigation signal as excitation signal for backscatter communication.Because the global navigation signal has the characteristics of all-weather and full coverage,this design solves the carrier acquisition problem in previous work.In addition,this paper also proposes a low-power signal detection technology that can detect navigation signals with high precision on passive devices.We evaluate system performance through simulation experiments.The experimental results show that the backscatter system based on global navigation satellite signals can realize efficient communication of IoT nodes.

Review of Inductance Identification Methods Considering Inverter Nonlinearity for PMSM

Permanent magnet synchronous motors(PMSMs)are widely used in high-power-density and flexible control methods.Generally,the inductance changes significantly in real-time machine operations because of magnetic saturation and coupling effects.Therefore,the identification of inductance is crucial for PMSM control.Existing inductance identification methods are primarily based on the voltage source inverter(VSI),making inverter nonlinearity one of the main error sources in inductance identification.To improve the accuracy of inductance identification,it is necessary to compensate for the inverter nonlinearity effect.In this study,an overview of the PMSM inductance identification and the related inverter nonlinearity self-learning methods are presented.

Magnetic iron oxide nanoparticles accelerate osteogenic differentiation of mesenchymal stem cells via modulation of long noncoding RNA INZEB2

Nanomaterials are increasingly used for biomedical applications; thus, it is important to understand their biological effects. Previous studies suggested that magnetic iron oxide nanoparticles （IONPs） have tissue-repairing effects. In the present study, we explored cellular effects of IONPs in mesenchymal stem cells （MSCs） and identified the underlying molecular mechanisms. The results showed that our as-prepared IONPs were structurally stable in MSCs and promoted osteogenic differentiation of MSCs as whole particles. Moreover, at the molecular level, we compared the gene expression of MSCs with or without IONP exposure and showed that IONPs upregulated long noncoding RNA INZEB2, which is indispensable for maintaining osteogenesis by MSCs. Furthermore, overexpression of INZEB2 downregulated ZEB2, a factor necessary to repress BMP/Smad- dependent osteogenic transcription. We also demonstrated that the essential role of INZEB2 in osteogenic differentiation was ZEB2-dependent. In summary, we elucidated the molecular basis of IONPs＇ effects on MSCs; these findings may serve as a meaningful theoretical foundation for applications of stem cells to regenerative medicine.

Freeform OST-HMD system with large exit pupil diameter and vision correction capability

Compactness and light weight,large exit pupil diameter and distance,small distortion for virtual image,and see-through light paths are pivotal factors to achieve a better,wearable experience of optical see-through headmounted displays(OST-HMDs).In addition,light efficiency of the virtual image light path is an important factor for heat dissipation in HMD devices.This paper presents a new type of OST-HMD optical system that includes three wedge-shaped freeform prisms and two symmetric lenses.Based on a 0.71 in.microdisplay,an OST-HMD prototype with a diagonal field of view(FOV)of 45.3°,an F-number(F/#)of 1.8,an exit pupil size of 12 mm×8 mm,and an eye relief of 18 mm is demonstrated.The maximum value of distortion of the final system is 0.6%and 0.4%for virtual image and see-through light path,respectively.The overall dimension of the optical system per eye is no larger than 30 mm(width)×40 mm(height)×14 mm(thickness),and the weight of the optical module including lenses,holder,and microdisplay is 12.8 g.The light efficiency of the virtual image light path is up to 50%higher than those of other OST-HMD optical solutions.

Inflammation-induced inhibition of chaperone-mediated autophagy maintains the immunosuppressive function of murine mesenchymal stromal cells

Macroautophagy has been implicated in modulating the therapeutic function of mesenchymal stromal cells(MSCs).However,the biological function of chaperone-mediated autophagy(CMA)in MSCs remains elusive.Here,we found that CMA was inhibited in MSCs in response to the proinflammatory cytokines interferon-γ(IFN-γ)and tumor necrosis factor-α(TNF-α).In addition,suppression of CMA by knocking down the CMA-related lysosomal receptor lysosomal-associated membrane protein 2(LAMP-2A)in MSCs significantly enhanced the immunosuppressive effect of MSCs on T cell proliferation,and as expected,LAMP-2A overexpression in MSCs exerted the opposite effect on T cell proliferation.This effect of CMA on the immunosuppressive function of MSCs was attributed to its negative regulation of the expression of chemokine C-X-C motif ligand 10(CXCL10),which recruits inflammatory cells,especially T cells,to MSCs,and inducible nitric oxide synthase(iNOS),which leads to the subsequent inhibition of T cell proliferation via nitric oxide(NO).Mechanistically,CMA inhibition dramatically promoted IFN-γplus TNF-α-induced activation of NF-κB and STAT1,leading to the enhanced expression of CXCL10 and iNOS in MSCs.Furthermore,we found that IFN-γplus TNF-α-induced AKT activation contributed to CMA inhibition in MSCs.More interestingly,CMA-deficient MSCs exhibited improved therapeutic efficacy in inflammatory liver injury.Taken together,our findings established CMA inhibition as a critical contributor to the immunosuppressive function of MSCs induced by inflammatory cytokines nd highlighted a previously unknown function of CMA.

Design and manufacture AR head-mounted displays:A review and outlook

Augmented reality head-mounted displays(AR-HMDs)enable users to see real images of the outside world and visualize virtual information generated by a computer at any time and from any location,making them useful for various applications.The manufacture of AR-HMDs combines the fields of optical engineering,optical materials,optical coating,precision manufacturing,electronic science,computer science,physiology,ergonomics,etc.This paper primarily focuses on the optical engineering of AR-HMDs.Optical combiners and display devices are used to combine real-world and virtual-world objects that are visible to the human eye.In this review,existing AR-HMD optical solutions employed for optical combiners are divided into three categories:optical solutions based on macro-,micro-,and nanooptics.The physical principles,optical structure,performance parameters,and manufacturing process of different types of AR-HMD optical solutions are subsequently analyzed.Moreover,their advantages and disadvantages are investigated and evaluated.In addition,the bottlenecks and future development trends in the case of AR-HMD optical solutions are discussed.

Laboratory study on efficiency of three calcium carbonate scale inhibitors in the presence of EOR chemicals

Chemical flooding has been widely used in the oil industry since the 1980s for enhanced oil recovery(EOR)process.Previous studies have shown that the effectiveness of calcium carbonate scale inhibitors is affected by many factors,such as water composition,system pressure,temperature,production rates,pH etc.The breakthrough of the EOR chemicals in the production well could also affect scale formation process and interfere with the scale treatment program as well.However,the studies on the impacts of injected EOR chemicals to scale inhibitor performances are very limited.This paper presents the comprehensive laboratory study on the impacts of the EOR chemicals on CaCO3 scale formation and prevention using static bottle and dynamic tube blocking methods.The EOR chemicals used in this study are a combination of surfactants and polymers.Three different types of inhibitors were evaluated:triphosphonate,penta-phosphonate,and polyacrylate based chemicals.Inhibition(%)from the bottle test and minimum effective dose(MED)based on the tube blocking method were determined for each inhibitor at 160
F.Scale precipitates from the bottle tests were also characterized for morphology and polymorphs using environmental scanning electron(ESEM)and X-ray diffraction(XRD)techniques.Results suggest that the performance of scale inhibitors could be substantially affected by the EOR chemicals.In dynamic tube blocking tests,the MED values of inhibitors were increased roughly 10 times with the EOR chemicals.The static bottle tests showed considerable changes under the test conditions.The impact of EOR chemicals were also demonstrated by the remarkable ranges of crystal morphologies,changing from simple aragonite columns to nanorod,distorted spheroid,and flower-like superstructure in the presence of EOR chemicals and inhibitors.