Mobility-Aware Caching Strategy in an SDN-Based Cooperative Caching Network

The upsurge of mobile multimedia traf-fic puts a heavy burden on the cellular network,and wireless caching has emerged as a powerful tech-nique to overcome the backhaul bottleneck and al-leviate the network burden.However,most previ-ous works ignored user mobility,thus not reaping the caching gain from user mobility and having lim-ited practical applications.In this paper,a mobility-aware caching strategy for the software-defined net-work(SDN)-based network is studied.Firstly,since typical mobile user(MU)has multiple opportunities to connect with the nearby MUs and Small-base stations(SBSs),the contact times between MUs as well as be-tween MU and SBSs are derived as the Poisson distri-bution and Gamma distribution.Secondly,we propose a two-tier cooperative caching strategy,where SBSs cache the rateless Fountain code encoded video blocks probabilistically and nonrepeatedly while MUs just store the whole encoded video received last time.The corresponding four-stage transmission process is ana-lyzed,where the key intermediate step is the deriva-tion of the service and the failing probabilities of each transmission manner.Finally,we derive the success-ful offloading rate and average data offloading ra-tio(ADOR)as performance metrics.A system op-timization problem based on ADOR is formulated,and two solutions are proposed,namely,derivativebased solution(DB-Solution)and long-tail distribution approximation(LTD-Approximation).Simulation results demonstrate that the effectiveness of LTDApproximation is similar to the DB-Solution,and the proposed caching strategy can achieve quasi-optimal performance compared with other contrast schemes.

Source of major ions from an ice core of the No.12 Glacier in Laohugou Valley,Qilian Mountain

In June 2006,a 20.12 m shallow ice core was recovered from an elevation of 5,040 m in the northern branch firn basin of No.12 Glacier,Great Snow Mountain,in the western part of Qilian Mountain,China.Isotopes(δ 18 O),major soluble ions,and radionuclide(β-activity) measurements from the ice core revealed a 46-year record(1960-2006).In this paper,the method of sea-salt ion tracer,correlation analysis and trend analysis were used in this research to confirm the source of the chemical composition.The correlation analysis and HYSPLIT backward trajectory analysis suggests that atmospheric soluble dust species dominate the chemical signature.

Enhancement in the Hg^(0) oxidation efficiency and sulfur resistance of CuCl_(2)-modified MnO_(x)-CeO_(x) nanorod catalysts

In this study,a series of CuCl_(2)-modified MnO_(x)-CeO_(x)nanorods were synthesized for the oxidation of Hg^(0).The addition of CuCl_(2)resulted in an enhancement in the catalyst’s Hg^(0)oxidation ability,and Hg^(0)oxidation efficiency reached>97%from 150 to 250°C.In the MnO_(x)-CeO_(x)catalysts,Mn^(4+)played the role of the active species for Hg^(0)oxidization,but in the CuCl_(2)-doped catalysts Cl−also contributed to Hg^(0)oxidation,conferring the superior performance of these samples.The introduction of SO_(2) led to a decrease in the availability of Mn^(4+),and the Hg^(0)oxidation efficiency of MnO_(x)-CeO_(x)decreased from about 100%to about 78%.By contrast,CuCl_(2)-promoted samples maintained a Hg^(0)oxidation efficiency of about 100%during the SO_(2) deactivation cycle due to the high reactivity of Cl−.

Mechanistic investigation on the Hg^(0)elimination ability of MnO_(x)-CeO_(x)nanorod adsorbents:effects of Mn/Ce molar ratio

Mercury pollution is created by coal combustion processes in multi-component systems.Adsorbent injection was identified as a potential strategy for capturing Hg^(0)from waste gases,with adsorbents serving as the primary component.The hydro-thermal approach was used to synthesize a series of MnO_(x)-CeO_(x)nanorod adsorbents with varying Mn/Ce molar ratios to maximize the Hg^(0)capture capabilities.Virgin CeO,had weak Hg elimination activity;<8%Hg^(0)removal efficiency was obtained from 150℃to 250℃.With the addition of MnOr,the amount of surface acid sites and the relative concentration of Mn4+increased.This ensured the sufficient adsorption and oxidation of Hg while overcoming the limitations of restricted adsorbate-adsorbent interactions caused by the lower surface area,endowing MnO_(x)-CeO_(x)with increased Hg^(0)removal capac-ity.When the molar ratio of Mn/Ce reached 6/4,the adsorbent's Hg^(0)removal efficiency remained over 92%at 150℃and 200℃.As the molar ratio of Mn/Ce grew,the adsorbent's Hg^(0)elimination capacity declined due to decreased surface area,weakened acidity,and decreased activity of Mn^(4+);<75%Hg^(0)removal efficiency was reached between 150℃and 250℃for virgin MnOx.Throughout the overall Hg'elimination reactions,Mn4+and O.were in charge of oxidizing Hg^(0)to Hg^(0),with Ce^(4+)acting as a promoter to aid in the regeneration of Mn^(4+),Because of its limited adaptability to flue gas components,further optimization of the MnO_(x)-CeO_(x)nanorod adsorbent is required.

Concentrations and light absorption properties of PM_(2.5) organic and black carbon based on online measurements in Lanzhou, China

To elucidate the variations in mass concentrations of organic carbon(OC)and black carbon(BC)in PM_(2.5) and their light absorption characteristics in Lanzhou,we conducted one-year online measurements by using a newly developed total carbon analyzer(TCA08)coupled with an aethalometer(AE33)from July 2018 to July 2019.The mean OC and BC concentrations were 6.4±4.4 and 2.0±1.3μg/m^(3),respectively.Clear seasonal variations were observed for both components,with winter having the highest concentrations,followed by autumn,spring,and summer.The diurnal variations of OC and BC concentrations were similar throughout the year,with daily two peaks occurring in the morning and evening,respectively.A relatively low OC/BC ratio(3.3±1.2,n=345)were observed,indicating that fossil fuel combustion was the primary source of the carbonaceous components.This is further substantiated by relatively low biomass burning contribution(f_(biomass):27.1%±11.3%)to BC using aethalometer based measurement though f_(biomass) value which increased significantly in winter(41.6%±5.7%).We estimated a considerable brown carbon(BrC)contribution to the total absorption coefficient(b_(abs))at 370 nm(yearly average of 30.8%±11.1%),with a winter maximum of 44.2%±4.1%and a summer minimum of 19.2%±4.2%.Calculation of the wavelength dependence of total b_(abs) revealed an annual mean AAE_(370-520) value of 4.2±0.5,with slightly higher values in spring and winter.The mass absorption cross-section of BrC also exhibited higher values in winter,with an annual mean of 5.4±1.9 m^(2)/g,reflecting the impact of emissions from increased biomass burning on BrC concentrations.

Regulation of signaling pathways in hair follicle stem cells

Hair follicle stem cells(HFSCs)reside in the bulge region of the outer root sheath of the hair follicle.They are considered slow-cycling cells that are endowed with multilineage differentiation potential and superior proliferative capacity.The normal morphology and periodic growth of HFSCs play a significant role in normal skin functions,wound repair and skin regeneration.The HFSCs involved in these pathophysiological processes are regulated by a series of cell signal transduction pathways,such as lymphoid enhancer factor/T-cell factor,Wnt/β-catenin,transforming growth factor-β/bone morphogenetic protein,Notch and Hedgehog.The mechanisms of the interactions among these signaling pathways and their regulatory effects on HFSCs have been previously studied,but many mechanisms are still unclear.This article reviews the regulation of hair follicles,HFSCs and related signaling pathways,with the aims of summarizing previous research results,revealing the regulatory mechanisms of HFSC proliferation and differentiation and providing important references and new ideas for treating clinical diseases.

Seasonality of carbonaceous aerosol composition and light absorption properties in Karachi,Pakistan

Characteristics of carbonaceous aerosol(CA)and its light absorption properties are limited in Karachi,which is one of the most polluted metropolitan cities in South Asia.This study presents a comprehensive measurement of seasonality of CA compositions and mass absorption cross-section(MAC)of elemental carbon(EC)and water-soluble organic carbon(WSOC)in total suspended particles(TSP)collected from February 2015 to March 2017 in the southwest part of Karachi.The average TSP,organic carbon(OC),and EC concentrations were extremely high with values as 391.0±217.0,37.2±28.0,and 8.53±6.97μg/m3,respectively.These components showed clear seasonal variations with high concentrations occurring during fall and winter followed by spring and summer.SO42-,NO3-,K+,and NH4+showed similar variations with CA,implying the significant influence on atmospheric pollutants from anthropogenic activities.Relatively lower OC/EG ratio(4.20±2.50)compared with remote regions further indicates fossil fuel combustion as a primary source of CA.Meanwhile,sea salt and soil dust are important contribution sources for TSP.The average MAC of EC(632 nm)and WSOC(365 nm)were 6.56±2.70 and 0.97±0.37 m2/g,respectively.MACEC is comparable to that in urban areas but lower than that in remote regions,indicating the significant influence of local emissions.MACwsoc showed opposite distribution with EC,further suggesting that OC was significantly affected by local fossil fuel combustion.In addition,dust might be an important factor increasing MACwsoc particularly during spring and summer.

Excellent thermal shock resistance of NiCrAlY coatings on copper substrate via laser cladding

Coatings are widely used to protect substrates in extreme thermal environments(e.g., arc heaters), and thermal shock resistance is a crucial parameter for the coatings, which requires tight interlayer bonding between coatings and substrates. In this work, Ni Cr Al Y coatings were highly required for the pure copper substrate to restrict the electric arc in arc heaters. To overcome the bonding difculty of coating on the copper surface, the Ni Cr Al Y coatings were prepared by two laser cladding methods: conventional laser cladding(CLC) and high-speed laser cladding(HSLC). The microstructure, composition, and thermal shock resistance of Ni Cr Al Y cladding layers prepared by both methods were investigated. Benefitting from the high cooling rate and high energy density, the HSLC-layer has better composition uniformity and tighter interlayer bonding than the CLC-layer, achieving a 30%–45% improvement in thermal cycling lifetime. Besides, the Ni Cr Al Y layers prepared on copper substrate by both laser cladding methods exhibit3–10 times better thermal shock resistance than those Ni Cr Al Y layers prepared by conventional spraying methods. It further confirms the great effects of metallurgical bonding and composition uniformity on the thermal shock resistance of coatings. The Ni Cr Al Y layers fail in the form of internal cracking and interface peeling, and the corresponding failure mechanism is discussed.

Non-thermal plasma enhances performances of biochar in wastewater treatment and energy storage applications

Surface functionalization or modification to introduce more oxygen-containing functional groups to biochar is an effective strategy for tuning the physicochemical properties and promoting follow-up applications.In this study,non-thermal plasma was applied for biochar surface carving before being used in contaminant removal and energy storage applications.The results showed that even a low dose of plasma exposure could introduce a high number density of oxygen-functional groups and enhance the hydrophilicity and metal affinity of the pristine biochar.The plasma-treated biochar enabled a faster metal-adsorption rate and a 40%higher maximum adsorption capacity of heavy metal ion Pb^(2+).Moreover,to add more functionality to biochar surface,biochar with and without plasma pre-treatment was activated by KOH at a temperature of 800℃.Using the same amount of KOH,the plasma treatment resulted in an activated carbon product with the larger BET surface area and pore volume.The performance of the treated activated carbon as a supercapacitor electrode was also substantially improved by>30%.This study may provide guidelines for enhancing the surface functionality and application performances of biochar using non-thermal-based techniques.

Prognostic significance of preoperative Naples prognostic score on short-and long-term outcomes after pancreatoduodenectomy for ampullary carcinoma

Background:The Naples prognostic score(NPS)is an effective and objective tool to assess the immune-nutritional status of patients with malignant tumors.The aim of this study was to investigate the clinical significance of preoperative NPS on short-and long-term outcomes after pancreatoduodenectomy(PD)for ampullary carcinoma.Methods:We retrospectively analyzed 404 consecutive patients with ampullary carcinoma who underwent PD between January 2012 and June 2018.Preoperative NPS was calculated from serum albumin and total cholesterol concentrations,and the neutrophil-lymphocyte ratio and lymphocyte-monocyte ratio(LMR).Patients were then divided into three groups according to their NPS.Clinicopathological variables,postoperative outcomes,and survival data were compared between the three groups.Univariate and multivariate Cox analysis of overall survival(OS)and recurrence-free survival(RFS)were also conducted,and time-dependent receiver operating characteristic(ROC)curves were created to evaluate the discriminatory ability of the prognostic scoring systems.Results:Patients with higher NPS had worse prognosis,and significant OS difference(group 0 vs.1,P=0.02;group 1 vs.2,P<0.001;group 0 vs.2,P<0.001)and RFS difference(group 0 vs.1,P=0.088;group 1 vs.2,P<0.001;group 0 vs.2,P<0.001).Multivariate analysis revealed that NPS was an independent significant predictor of OS(grade 2 vs.grade 1 or 0,hazard ratio:3.067;P<0.001)and RFS(grade 2 vs.grade 1 or 0,hazard ratio:2.732;P<0.001).The time-dependent receiver operating curve analysis showed that NPS had better prognostic performance for OS and RFS than other prognostic models.Additionally,significant differences in the incidence of postoperative morbidity were observed between the three groups,and the NPS was an independent risk factor of overall postoperative complications(grade 2 vs.grade 1 or 0,odds ratio:1.692;P=0.02).Conclusions:The NPS was an independent predictor of overall-and RFS in patients undergoing PD for ampullary carcinoma,and was independently associated with the incidence of postoperative complications.

Structure and Roles of the Various Layers in the Shells of Conch Conus litteratus

Mollusc shells are renowned for their mechanical strength and toughness. To better understand the mineralization process of the shell, structure of the body whorl and base of Conus litteratus （Conus shell） were in detail investigated by using scanning electron microscopy. Three-point bending tests were taken to demonstrate that each layer of crossed-lamellar structures is indispensable to enhance the whole strength of the shells. The results show that the conch shell is composed of hierarchical structure from nano scale to macro scale, and the basic constituent is long rod-shaped aragonite. Different positions of the shell have varied structures, and the base is more complicated than the body whorl. The mechanical properties of Conus are highly anisotropic and the arrangement of middle layer has a great influence on the bending strength. The outer and inner layers are very thin but play a protective role for the middle layer.

Optimizing flow field in an SCR system of a 600 MW power plant:effects of static mixer alignment style

The fluid flow in a selective catalytic reduction(SCR)system of a 600 MW power station is optimized using the numerical simulation method in this work.Given that guide plates and straightening gratings are properly installed,the relative standard deviation(C_(v))of velocity related to the inlet of an ammonia injection grid(AIG)and catalysts satisfy the engineering demand of<15%,suggesting that a relatively uniform velocity field is obtained.The in-line arrangement of static mixers strengthens the disturbance of fluid,promoting the mixing of reductant NH_(3)with flue gas.The NH_(3)mole fraction C_(v)value correlated to the inlet of catalysts drops to ca.3.5%,which is lower than that in the cases when the mixers are aligned in a staggered style.These results indicate that a solid foundation is achieved for the effective abatement of NO_(x)in practical applications.

Flower-like Cu5Sn2S7/ZnS nanocomposite for high performance supercapacitor

Ternary nanocomposites of CuxZnySnzS(x+y+z)are considered as an emerging potential candidate as electrode materials for energy storage devices due to the considerable interlayer spaces and tunnels in its crystal structures with excellent conducting ability.Recently,this nanocomposite used as anode material for Li-ion battery has been reported,but there is lim让ed research on让s application in supercapacitors which is considered a complementary energy storage device to battery.In this work,flower-like Cu5Sn2S7/ZnS and pristine Cu5Sn2S7 nanocomposite were prepared via a facile hydrothermal method.The electrochemical tests showed that the Cu5Sn2S7/ZnS nanocomposite exhibited better performance than pristine Cu5Zn2S7,suggesting that the existence of ZnS could significantly enhance the electrochemical performance of Cu5Sn2S7,with the good capacitance of 200 F/g at the current density of 1 A/g.Furthermore 170 F/g was obtained at the large current density of 10 A/g.Supercapacitors demonstrated energy density of 11.08 Wh/kg with power density 461 W/kg or 9.67 Wh/kg at power density of 4615 W/kg.

Efficient production of mannosylerythritol lipids by a marine yeast Moesziomyces aphidis XM01 and their application as self‑assembly nanomicelles

Mannosylerythritol lipids(MELs)are one of the most promising biosurfactants because of their excellent physicochemical properties,high environmental compatibility,and various biological functions.In this study,a mangrove yeast strain Moesziomyces aphidis XM01 was identified and used for efficient extracellular MEL production.The MEL titer reached 64.5±0.7 g/L at flask level within 7 days with the optimized nitrogen and carbon source of 2.0 g/L NaNO_(3) and 70 g/L soybean oil.Furthermore,during a 10-L two-stage fed-batch fermentation,the final MEL titer reached 113.6±3.1 g/L within 8 days,with prominent productivity and yield of 14.2 g·L^(−1)·day^(−1)and 94.6 g/g_((glucose and soybean oil)).Structural analysis indicated that the produced MELs were mainly MEL-A and its fatty acid profile was composed of only medium-chain fatty acids(C8–C12),especially C10 acids(77.81%).Further applications of this compound were evaluated as one-step selfassembly nanomicelles.The obtained MEL nanomicelles showed good physicochemical stability and antibacterial activity.In addition,using clarithromycin as a model hydrophobic drug,the MEL nanomicelles exhibited high loading capacity and could be used for the controlled and sustained drug release in low-pH environments.Therefore,M.aphidis XM01 is an excellent candidate for efficient MEL production,and the prepared MEL nanomicelles have broad application prospects in the pharmaceutical and cosmetic fields.

The Carbon Effects of the Urban Ecological Recreational System Based on Systems Simulation

As a major component of urban ecological systems, the urban ecological space is an important carbon pool in the urban carbon circulation. Meanwhile, its special recreational function adds to the complexity of its carbon effects. According to the carbon process and effects of the urban ecological recreational system, the Source-Leakage-Sink-Order(SLSO) framework is proposed as the basis of the four subsystems of the system model. Consisting of 63 parameters, the system dynamics model of urban ecological recreational system is constructed by using VENSIM PLE. Then the urban ecological recreational system in Shanghai under different scenarios is simulated, and the carbon sources and sinks of the system as well as the process of carbon effects such as carbon footprints are analyzed and predicted. Research shows that due to the imbalance of the spatial pattern of ecological recreational space, the carbon sink effects of the system are quite limited. The human carbon source is the main contributor of the system’s carbon sources and the carbon footprint deficit is striking. The management ability of ecological recreational space influences the carbon sink potentials of the system. In addition,the maintenance mode of ecological green space plays a non-trivial role in the composition of carbon sources.

New insights into the relationships between performance and physicochemical properties of FeO_(x)-NbO_(x)mixed oxide catalysts for the NH_(3)-SCR reactions

In this study,we prepared Fe_(2)O_(3)-Nb_(2)O_(5)binary mixed oxide catalysts using co-precipitation(CP),sol-gel(SG),and solid process(SR)methods and tested their performance.All the catalysts exhibited over 75%NO_(x)removal efficiency between 250℃and 400℃.Compared with the samples prepared by the SR method,catalyst synthesized using CP and SG methods possessed a larger specific surface area,which could compensate for the lower surface area-normalized reaction rate originat-ing from the insufficient reactive surface oxygen species,hence exhibiting a relatively high low-temperature apparent deNO_(x)activity.However,at a high-temperature region,limited amount of reactive surface oxygen species,together with abundant strong acid sites,facilitated the proceeding of NH_(3)reduction of NO_(x),which well explained the higher apparent activity of the catalyst prepared by SG method than the other two samples.It seemed that specific surface area had an important role to play in the low-temperature apparent performance of the catalysts,while chemical properties mainly decided the activity at an elevated temperature.