境内外原油期货价格动态关联性研究——兼论中国原油期货的市场影响力

基于DCC-GARCH模型和TVP-VAR-SV模型,考察上海原油期货与境外代表性原油期货价格之间的动态关联性。结果表明:境内外原油期货间的价格关联性具有显著的非对称性和时变特征。与新型冠状病毒感染暴发前相比,暴发后境内油价与境外油价间的关联性急剧上升,且前者对后者的冲击影响明显大于后者对前者的冲击影响;在此作用下,上海原油对阿曼原油的风险溢出具有长期性和持续性,而新型冠状病毒感染引致的上海原油与WTI和Brent原油间的风险溢出主要体现在短期、影响呈暂时性;境内外油价的互动影响在新型冠状病毒感染流行期大于暴发初期;总体而言,上海原油期货已具备相当的区域定价能力与一定的国际影响力,价格独立性初显,但其稳定性和抗风险能力还有待提升。

Cynodon dactylon andSida acuta extracts impact on the function of the cardiovascular system in zebrafish embryos

The aim of the present study was to screen cardioactive herbs from Western Ghats of India. The heart beat rate （HBR） and blood flow during systole and diastole were tested in zebrafish embryos. We found that Cynodon dactylon （C. dactylon） induced increases in the HBR in zebrafish embryos with a HBR of （3.968±0.344） beats/ s, which was significantly higher than that caused by betamethosone [（3.770±0.344） beats/s]. The EC50 value of C. dactylon was 3.738 μg/mL. The methanolic extract of Sida acuta （S. acuta） led to decreases in the HBR in zebrafish embryos [（1.877 ±0.079） beats/s], which was greater than that caused by nebivolol （positive control）. The EC50 value of Sida acuta was 1.195 μg/mL. The untreated embryos had a HBR of （2.685±0.160） beats/s at 3 d post fertilization （dpf）. The velocities of blood flow during the cardiac cycle were （2,291.667 ±72.169） μm/s for the control, （4,250± 125.000） μm/s for C. dactylon and （1,083.333±72.169） μm/s for S. acuta. The LC50 values were 32.6 μg/mL for C. dactylon and 20.9 μg/mL for S. acuta. In addition, the extracts exhibited no chemical genetic effects in the drug dosage range tested. In conclusion, we developed an assay that can measure changes in cardiac function in response to herbal small molecules and determine the cardiogenic effects by microvideography.

Isolation of a small molecule with anti-MRSA activity from a mangrove symbiont Streptomyces sp.PVRK-1 and its biomedical studies in Zebrafish embryos

Objective:The aim of the present study was to isolate the anti-MRSA(Methicillin Resistant Staphylococcus aureus)molecule from the Mangrove symbiont Streptomyces and its biomedical studies in Zebrafish embryos.Methods:MRSA was isolated from the pus samples of Colachal hospitals and confirmed by amplification of mecA gene.Anti-MRSA molecule producing strain was identified by!6s rRNA gene sequencing.Anti-MRSA compound production was optimized by Solid State Fermentation(SSF)and the purification of the active molecule was carried out by TLC and RP-HPLC.The inhibitory concentration and LC_(50)were calculated using Statistical software SPSS.The Biomedical studies including the cardiac assay and organ toxicity assessment were carried out in Zebraiish.Results:The bioactive anti-MRSA small molecule A,was purified by TLC with Rf value of 0.37 with 1.389 retention time at RP-HPLC.The Inhibitory Concentration of the purified molecule A_2 was 30μg/mL but,the inhibitory concentration of the MRSA in the infected embryo was 32-34μg/mL for TLC purified molecule A,with LC_(50)mean value was61.504μg/mL.Zebrafish toxicity was assessed in 48-60μg/mL by observing the physiological deformities and the heart beat rates(HBR)of embryos for anti MRSA molecule showed the mean of 41.33-41.67 HBR/15 seconds for 40μg/mL and control was 42.33-42.67 for 15 seconds which significantly showed that the anti-MRSA molecule A_2 did not affected the HBR.Conclusions:Anti-MRSA molecule from Streptomyces sp PVRK-I was isolated and biomedical studies in Zebrafish model assessed that the molecule was non toxic at the minimal inhibitory concentration of MRSA.

A symmetric MnO_2/MnO_2 flexible solid state supercapacitor operating at 1.6V with aqueous gel electrolyte

The demand of microelectronic devices postulated high energetic flexible energy storage devices. Flexible solid state supercapacitor is flawless possible candidate to fulfill the requirement of microelectronic devices. This investigation provides practical evidence of the use of flexible solid state supercapacitors based on MnOelectrodes with polyvinylpyrrolidone(PVP)-Li ClOgel electrolyte. Initially, different acid mediated growths of MnOhave been carried. Later, the electrochemical performances of MnOelectrodes have been carried out. Impressively, the fabricated symmetric flexible solid state supercapacitor(FSS-SC) device demonstrates the highest operating potential window of 1.6 V with extended cycling stability. Moreover, the cell exhibits high energy density of 23 Wh/kg at power density of 1.9 k W/kg. It is interesting to note that the device shows excellent flexibility upon bending at angle of 180° for number of times. These results clearly evidenced those symmetric FSS-SC devices based on MnOelectrodes are promising energy storage devices for microelectronic applications.

Additive engineering for stable halide perovskite solar cells

Halide perovskite solar cells(PSCs)have already demonstrated power conversion efficiencies above 25%,which makes them one of the most attractive photovoltaic technologies.However,one of the main bottlenecks towards their commercialization is their long-term stability,which should exceed the 20-year mark.Additive engineering is an effective pathway for the enhancement of device lifetime.Additives applied as organic or inorganic compounds,improve crystal grain growth enhancing power conversion efficiency.The interaction of their functional groups with the halide perovskite(HP)absorber,as well as with the transport layers,results in defect passivation and ion immobilization improving device performance and stability.In this review,we briefly summarize the different types of additives recently applied in PSC to enhance not only efficiency but also long-term stability.We discuss the different mechanism behind additive engineering and the role of the functional groups of these additives for defect passivation.Special emphasis is given to their effect on the stability of PSCs under environmental conditions such as humidity,atmosphere,light irradiation(UV,visible)or heat,taking into account the recently reported ISOS protocols.We also discuss the relation between deep-defect passivation,non-radiative recombination and device efficiency,as well as the possible relation between shallow-defect passivation,ion immobilization and device operational stability.Finally,insights into the challenge and criteria for additive selection are provided for the further stability enhancement of PSCs.

Emerging properties of non-crystalline phases of graphene and boron nitride based materials

We review recent developments on the synthesis and properties of two-dimensional materials which, although being mainly of an sp^(2) bonding character, exhibit highly disordered, non-uniform and structurally random morphologies. The emergence of such class of amorphous materials, including amorphous graphene and boron nitride, have shown superior properties compared to their crystalline counterparts when used as interfacial films. In this paper we discuss their structural,vibrational and electronic properties and present a perspective of their use for electronic applications.

Brain-derived neurotrophic factor as a potential biomarker of cognitive recovery in schizophrenia

Brain-derived neurotrophic factor(BDNF) has been proposed as a biomarker of schizophrenia and, more specifically, as a biomarker of cognitive recovery. Evidence collected in this review indicates that BDNF is relevant in the pathophysiology of schizophrenia and could play a role as a marker of clinical response. BDNF has been shown to play a positive role as a marker in antipsychotic treatment, and it has been demonstrated that typical antipsychotics decrease BDNF levels while atypical antipsychotics maintain or increase serum BDNF levels. Furthermore, BDNF levels have been associated with severe cognitive impairments in patients with schizophrenia. Consequently, BDNF has been proposed as a candidate target of strategies to aid the cognitive recovery process. There is some evidence suggesting that BDNF could be mediating neurobiological processes underlying cognitive recovery. Thus, serum BDNF levels seem to be involved in some synaptic plasticity and neurotransmission processes. Additionally, serum BDNF levels significantly increased in schizophrenia subjects after neuroplasticity-based cognitive training. If positive replications of those findings are published in the future then serum BDNF levels could be definitely postulated as a peripheral biomarker for the effects of intensive cognitive training or any sort of cognitive recovery in schizophrenia. All in all, the current consideration of BDNF as a biomarker of cognitive recovery in schizophrenia is promising but still premature.

Phase formation and thermoelectric properties of Zn_(1+x)Sb binary system

The phase formation and thermoelectric(TE)properties in the central region of the Zn−Sb phase diagram were analyzed through synthesizing a series of Zn_(1+x)Sb(x=0,0.05,0.1,0.15,0.25,0.3)materials by reacting Zn and Sb powders below the solidus line of the Zn−Sb binary phase diagram followed by furnace cooling.In this process,the nonstoichiometric powder blend crystallized in a combination of ZnSb andβ-Zn4Sb3 phases.Then,the materials were ground and hot pressed to form dense ZnSb/β-Zn4Sb3 composites.No traces of Sb and Zn elements or other phases were revealed by X-ray diffraction,high resolution transmission electron microscopy and electron energy loss spectroscopy analyses.The thermoelectric properties of all materials could be rationalized as a combination of the thermoelectric behavior of ZnSb andβ-Zn4Sb3 phases,which were dominated by the main phase in each sample.Zn1.3Sb composite exhibited the best thermoelectric performance.It was also found that Ge doping substantially increased the Seebeck coefficient of Zn1.3Sb and led to significantly higher power factor,up to 1.51 mW·m−1·K−2 at 540 K.Overall,an exceptional and stable TE figure of merit(ZT)of 1.17 at 650 K was obtained for Zn1.28Ge0.02Sb.

面向生态可持续的下一代通信网络架构与评价体系

随着新一代通信技术的迅猛发展和万物互联时代的到来,通信基础设施的新增部署和能源消耗增大,也带来了潜在的网络安全和生态环境影响等问题.面向第6代移动通信系统(6G)网络架构的研究应从对网络性能和用户体验的关注逐步扩展到对网络全方位可持续性发展的关注.在传统网络的基础上,探讨了面向6G的生态可持续网络架构设计,讨论了多层次的系统构建框架,并分析了6G网络与现实物理世界的动态交互.考虑到对网络可持续性能等方面的评估需求,设计了面向新型网络架构的综合评价体系.针对网络多维跨域可持续性能的分析,给出了基于机器学习的通信网络评价方法,为网络的生态可持续能力的构建和优化提供参考.

Toward integrated detection and graphene-based removal of contaminants in a lab-on-a-chip platform

A novel miniaturized microfluidic platform was developed for the simultaneous detection and removal of polybrominated diphenyl ethers （PBDEs）. The platform consists of a polydimethylsiloxane （PDMS） microfluidic chip for an immunoreaction step, a PDMS chip with an integrated screen-printed electrode （SPCE） for detection, and a PDMS-reduced graphene oxide （rGO） chip for physical adsorption and subsequent removal of PBDE residues. The detection was based on competitive immunoassay-linked binding between PBDE and PBDE modified with horseradish peroxidase （HRP-PBDE） followed by the monitoring of enzymatic oxidation of o-aminophenol （o-AP） using square wave anodic stripping voltammetry （SW-ASV）. PBDE was detected with good sensitivity and a limit of detection similar to that obtained with a commercial colorimetric test （0.018 ppb）, but with the advantage of using lower reagent volumes and a reduced analysis time. The use of microfluidic chips also provides improved linearity and a better reproducibility in comparison to those obtained with batch-based measurements using screen-printed electrodes. In order to design a detection system suitable for toxic compounds such as PBDEs, a reduced graphene oxide-PDMS composite was developed and optimized to obtain increased adsorption （based on both the hydrophobicity and rr-v~ stacking between rGO and PBDE molecules） compared to those of non-modified PDMS. To the best of our knowledge, this is the first demonstration of electrochemical detection of flame retardants and a novel application of the rGO-PDMS composite in a biosensing system. This system can be easily applied to detect any analyte using the appropriate immunoassay and it supports operation in complex matrices such as seawater.

Triple lines gold nanoparticle-based lateral flow assay for enhanced and simultaneous detection of Leishmania DNA and endogenous control

A novel triple lines lateral-flow assay （LFA） with enhanced sensitivity for the detection of Leishmania infantum DNA in dog blood samples was designed and successfully applied. The enhanced LFA methodology takes advantage of the gold nanoparticle tags （AuNPs） conjugated to polyclonal secondary antibodies, which recognize anti-FITC antibodies. The polyclonal nature of the secondary antibodies allows for multiple binding to primary antibodies, leading to enhanced AuNP plasmonics signal. Furthermore, endogenous control consisting of the amplified dog 18S rRNA gene was introduced to avoid false negatives. Using this strategy, 0.038 spiked Leishmania parasites per DNA amplification reaction （1 parasite/100 μL of DNA sample） were detected. Detection limit of LFA was found to be lower than that of the conventional techniques. In summary, our novel LFA design is a universal and simple sensing altemative that can be extended to several other biosensing scenarios.

Milliwatt terahertz harmonic generation from topological insulator metamaterials

Achieving effcient,high-power harmonic generation in the terahertz spectral domain has technological applications,for example,in sixth generation(6G)communication networks.Massless Dirac fermions possess extremely large terahertz nonlinear susceptibilities and harmonic conversion effciencies.However,the observed maximum generated harmonic power is limited,because of saturation effects at increasing incident powers,as shown recently for graphene.Here,we demonstrate room-temperature terahertz harmonic generation in a Bi_(2)Se_(3) topological insulator and topological-insulator-grating metamaterial structures with surface-selective terahertz field enhancement.We obtain a third-harmonic power approaching the miliwatt range for an incident power of 75 mW-an improvement by two orders of magnitude compared to a benchmarked graphene sample.We establish a framework in which this exceptional performance is the result of thermodynamic harmonic generation by the massless topological surface states,benefiting from ultrafast dissipation of electronic heat via surface-bulk Coulomb interactions.These results are an important step towards on-chip terahertz(opto)electronic applications.

Supergiant Barocaloric Effects in Acetoxy Silicone Rubber over a Wide Temperature Range:Great Potential for Solid-state Cooling

Solid-state cooling based on caloric effects is considered a viable alternative to replace the conventional vapor-compression refrigeration systems.Regarding barocaloric materials,recent results show that elastomers are promising candidates for cooling applications around room-temperature.In the present paper,we report supergiant barocaloric effects observed in acetoxy silicone rubber—a very popular,low-cost and environmentally friendly elastomer.Huge values of adiabatic temperature change and reversible isothermal entropy change were obtained upon moderate applied pressures and relatively low strains.These huge barocaloric changes are associated both to the polymer chain rearrangements induced by confined compression and to the first-order structural transition.The results are comparable to the best barocaloric materials reported so far,opening encouraging prospects for the application of elastomers in near future solid-state cooling devices.

Heterogeneous catalysts with programmable topologies generated by reticulation of organocatalysts into metal-organic frameworks:The case of squaramide

A well-established strategy to synthesize heterogeneous,metal-organic framework(MOF)catalysts that exhibit nanoconfinement effects,and specific pores with highly-localized catalytic sites,is to use organic linkers containing organocatalytic centers.Here,we report that by combining this linker approach with reticular chemistry,and exploiting three-dimensioanl(3D)MOF-structural data from the Cambridge Structural Database,we have designed four heterogeneous MOF-based catalysts for standard organic transformations.These programmable MOFs are isoreticular versions of pcu IRMOF-16,feu UiO-68 and pillared-pcu SNU-8X,the three most common topologies of MOFs built from the organic linker p.p'-terphenyldicarboxylic acid(tpdc).To synthesize the four squaramide-based MOFs,we designed and synthesized a linker,4,4’-((3,4-dioxocyclobut-1-ene-1,2-diyl)bis(azanedyil))dibenzoic acid(Sq_tpdc),which is identical in directionality and length to tpdc but which contains organocatalytic squaramide centers.Squaramides were chosen because their immobilization into a framework enhances its reactivity and stability while avoiding any self-quenching phenomena.Therefore,the four MOFs share the same organocatalytic squaramide moiety,but confine it within distinct pore environments.We then evaluated these MOFs as heterogeneous H-bonding catalysts in organic transformations:a Friedel-Crafts alkylation and an epoxide ring-opening.Some of them exhibited good performance in both reactions but all showed distinct catalytic profiles that reflect their structural differences.

Angular dependence of nanoparticle generation in the matrix assembly cluster source

The matrix assembly cluster source(MACS)represents a bridge between conventional instruments for cluster beam deposition(CBD)and thelevel of industrial production.The method is based on Ar^+ion sputtering of a pre-condensed Ar-M matrix(where M,is typically a metal such asAg).Each Ar^+ion produces a collision cascade and thus the formation of metal clusters is in the matrix,which are then sputtered out.Here wepresent an experimental and computational investigation of the cluster emission process,specifically its dependence on the Ar^+ion angle of in cidence and the cluster emission angle.We find the in cide nee angle strongly in flue nces the emerging cluster flux,which is assigned to thespatial location of the deposited primary ion energy relative to the cluster into the matrix.We also found an approximately constant anglebetween the incident ion beam and the peak in the emitted cluster distribution,with value between 99°and 109°.

Strain-induced spatially indirect exciton recombination in zinc-blende/wurtzite CdS heterostructures

Strain engineering provides an effective mean of tuning the fundamental properties of semiconductors for electric and optoelectronic applications. Here we report on how the applied strain changes the emission properties of hetero- structures consisting of different crystalline phases in the same CdS nanobelts. The strained portion was found to produce an additional emission peak on the low-energy side that was blueshifted with increasing strain. Furthermore, the additional emission peak obeyed the Varshni equation with temperature and exhibited the band-filling effect at high excitation power. This new emission peak may be attributed to spatially indirect exciton recombination between different crystalline phases of CdS. First-principles calculations were performed based on the spatially indirect exciton recombination, and the calculated and experimental results agreed with one another. Strain proved to be capable of enhancing the anti-Stokes emission, suggesting that the efficiency of laser cooling may be improved by strain engineering.

Waste Tire Rubber-based Refrigerants for Solid-state Cooling Devices

Management of discarded tires is a compelling environmental issue worldwide.Although there are several approaches developed to recycle waste tire rubbers,their application in solid-state cooling is still unexplored.Considering the high barocaloric potential verified for elastomers,the use of waste tire rubber(WTR)as a refrigerant in solid-state cooling devices is very promising.Herein,we investigated the barocaloric effects in WTR and polymer blends made of vulcanized natural rubber(VNR)and WTR,to evaluate its feasibility for solid-state cooling technologies.The adiabatic temperature changes and the isothermal entropy changes reach giant values,as well as the performance parameters,being comparable or even better than most barocaloric materials in literature.Moreover,pure WTR and WTR-based samples also present a faster thermal exchange than VNR,consisting of an additional advantage of using these discarded materials.Thus,the present findings evidence the encouraging perspectives of employing waste rubbers in solid-state cooling based on barocaloric effects,contributing to both the recycling of polymers and the sustainable energy technology field.

The elphbolt ab initio solver for the coupled electron-phonon Boltzmann transport equations

elphbolt is a modern Fortran (2018 standard) code for efficiently solving the coupled electron–phonon Boltzmann transport equations from first principles.Using results from density functional and density functional perturbation theory as inputs,it can calculate the effect of the non-equilibrium phonons on the electronic transport (phonon drag) and non-equilibrium electrons on the phononic transport (electron drag) in a fully self-consistent manner and obeying the constraints mandated by thermodynamics.It can calculate the lattice,charge,and thermoelectric transport coefficients for the temperature gradient and electric fields,and the effect of the mutual electron–phonon drag on these transport properties.The code fully exploits the symmetries of the crystal and the transport-active window to allow the sampling of extremely fine electron and phonon wave vector meshes required for accurately capturing the drag phenomena.The coarray feature of modern Fortran,which offers native and convenient support for parallelization,is utilized.The code is compact,readable,well-documented,and extensible by design.

Nanoparticles-based nanochannels assembled on a plastic flexible substrate for label-free immunosensing

A novel, cheap, disposable and single-use nanoparticles-based nanochannel platform assembled on a flexible substrate for label-free immunosensing is pre- sented. This sensing platform is formed by the dip-coating of a homogeneous and assembled monolayer of carboxylated polystyrene nanospheres （PS, 200 and 500 nm-sized） onto the working area of flexible screen-printed indium tin oxide/polyethylene terephthalate （ITO/PET） electrodes. The spaces between the self-assembled nanospheres generate well-ordered nanochannels, with inter-PS particles distances of around 65 and 24 nm respectively. The formed nanochannels are used for the effective immobilization of antibodies and subsequent protein detection based on the monitoring of [Fe（CN）6]^4- flow through diffusion and the decrease in the differential pulse voltammetric signal upon immunocomplex formation. The obtained sensing system is nanochannel-size dependent and allows human immunoglobulin G （IgG） （chosen as a model analyte） to be detected at levels of 580 ng/mL. The system also exhibits an excellent specificity against other proteins present in real samples and shows good performance with a human urine sample. The developed device represents an integrated and simple biodetection system which overcomes many of the limitations of previously reported nanochannels-based approaches and can be extended in the future to several other immuno and DNA detection systems.

Graphene quantum dots: From efficient preparation to safe renal excretion

Carbon nanomaterials offer excellent prospects as therapeutic agents,and among them,graphene quantum dots(GQDs)have gained considerable interest thanks to their aqueous solubility and intrinsic fluorescence,which enable their possible use in theranostic approaches,if their biocompatibility and favorable pharmacokinetic are confirmed.We prepared ultra-small GQDs using an alternative,reproducible,top-down synthesis starting from graphene oxide with a nearly 100%conversion.The materials were tested to assess their safety,demonstrating good biocompatibility and ability in passing the ultrafiltration barrier using an in vitro model.This leads to renal excretion without affecting the kidneys.Moreover,we studied the GQDs in vivo biodistribution confirming their efficient renal clearance,and we demonstrated that the internalization mechanism into podocytes is caveolae-mediated.Therefore,considering the reported characteristics,it appears possible to vehiculate compounds to kidneys by means of GQDs,overcoming problems related to lysosomal degradation.