Using the data of conductivity-temperature-depth (CTD) intensive observations conducted during Oct.-Nov.2005,this study provides the first three-dimension quasi-synoptic description of the circulation in the western North Pacific.Several novel phenomena are revealed,especially in the deep ocean where earlier observations were very sparse.During the observations,the North Equatorial Current (NEC) splits at about 12°N near the sea surface.This bifurcation shifts northward with depth,reaching about 20°N at 1 000 m,and then remains nearly unchanged to as deep as 2 000 m.The Luzon Undercurrent (LUC),emerging below the Kuroshio from about 21°N,intensifies southward,with its upper boundary surfacing around 12°N.From there,part of the LUC separates from the coast,while the rest continues southward to join the Mindanao Current (MC).The MC extends to 2 000 m near the coast,and appears to be closely related to the subsurface cyclonic eddies which overlap low-salinity water from the North Pacific.The Mindanao Undercurrent (MUC),carrying waters from the South Pacific,shifts eastward upon approaching the Mindanao coast and eventually becomes part of the eastward undercurrent between 10°N and 12°N at 130°E.In the upper 2 000 dbar,the total westward transport across 130oE between 7.5oN and 18oN reaches 65.4 Sv (1 Sv=10-6 m3s-1),the northward transport across 18oN from Luzon coast to 130oE is up to 35.0 Sv,and the southward transport across 7.5oN from Mindanao coast to 130oE is 27.9 Sv.
Remarkable advances in fast magic-angle spinning(MAS)techniques significantly improve the resolution of^(1)H solid-state nuclear magnetic resonance(NMR)spectra.Here,we introduce a heteronuclear-filtered^(1)H homonuclear multi-quantum(MQ)correlation strategy available at a MAS rate of 100 kHz by combining^(1)H{X}heteronuclear-filtered methods and^(1)H homonuclear MQ correlation experiments.The proposed strategy was applied to selectively extract^(1)H signals of aluminum lactate(Al-Lac)in a mixture of Al-Lac and zinc lactate(Zn-Lac)using 27Al-filtered methods(i.e.,^(1)H{27Al}heteronuclear multiple quantum correlation(HMQC)or^(1)H{27Al}symmetry-based resonance-echo saturationpulse double-resonance(S-RESPDOR)).We demonstrate that incorporating these 27Al-filtered methods into two-dimensional(2D)^(1)He^(1)H double-quantum(DQ)/single-quantum(SQ),triple-quantum(TQ)/SQ,and even three-dimensional(3D)27Al/^(1)H(DQ)/^(1)H(SQ)experiments can facilitate the acquisition of spectra without signal overlap and targeted characterization of the^(1)H species surrounding 27Al sites.The proposed strategy is considered to efficiently extract key structural information from complex spin systems.
Mingji ZhengShuangqin ZengXiumei WangXiuzhi GaoQiang WangJun XuFeng Deng
Molecular dynamics simulations are employed to study the nanometric machining process of single crystal nickel. Atoms from different machining zones had different atomic crystal structures owing to the differences in the actions of the cutting tool. The stacking fault tetrahedral was formed by a series of dislocation reactions, and it maintained the stable structure after the dislocation reactions. In addition, evidence of crystal transition and recovery was found by analyzing the number variations in different types of atoms in the primary shear zone, amorphous region, and crystalline region. The effects of machining speed on the cutting force, chip and subsurface defects, and temperature of the contact zone between the tool and workpiece were investigated. The results suggest that higher the machining speed, larger is the cutting force. The degree of amorphousness of chip atoms and the depth and extent of subsurface defects increase with the machining speed. The average friction coefficient first decreases and then increases with the machining speed because of the temperature difference between the chip and machining surface.
Designing high efficacy photocatalysts is a promising way to improve solar fuel production efficiency.In this work,we prepared a core/shell composite of loose ZnCr layered double hydroxide nanosheets modified CdS nanorods for efficient visible light driven photocatalytic hydrogen production.The highest hydrogen production rate achieved 425.8μmol·h^(−1) without adding any noble metal cocatalyst under the visible light stimulus,which is 22.4 times that of 1 wt.%Pt-modified CdS.The corresponding apparent quantum yield is 13.9%at 420 nm.It is revealed that the synergistic actions of the interfacial redox shuttle of Cr^(3+)/Cr^(δ+)and the interfacial electric field enable the efficient separation of photoinduced charge carriers between two components via a Z-scheme energy band configuration.Meanwhile,with the hydrogen evolution contribution of Zn^(2+),a remarkable improvement in photocatalytic performance was achieved in contrast to bare CdS.This work provides an effective methodology to construct highly efficient and economically viable photocatalysts for solar H_(2)production and mechanistic study.
In modern microprocessors, the multi-port register file is one of the key modules which provides fast and multiple data access for instructions. As the number of access ports in register files increases, stability becomes a key issue due to the voltage fluctuation on bit lines. We propose to apply an isolated inverter to address the voltage fluctuation. To assess the register stability, we derive a closed-form expression of static noise margin(SNM) for our register file. The proposed SNM model can be used as a guideline to predict the impact of several register parameters on the stability and optimize register file designs. To validate the proposed SNM model, we fabricated a test chip of two-write-four-read(2W4R) 1024 bits register file in a TSMC 65 nm low-power CMOS technology.The experimental result shows that the stability of our register file cells with an isolated inverter improve the conventional cells by approximately 2.4 times. Also, the supply voltage causes a fluctuation of SNM of about 65%,while temperature and transistor mismatch cause a fluctuation of SNM of about 20%.
Despite progress over the past few years in developing efficient low-cost catalysts,precious metals are still the best catalysts for hydrogen evolution reaction(HER),oxygen evolution reaction(OER),and oxygen reduction reaction(ORR).However;the natural scarcity and high cost greatly hamper their large-scale commercialization.The combination of graphene shell with metal core could tune the electronic structure of carbon active sites.Recently,nitrogen doped graphene encapsulated metal or alloy(M@NG)has emerged as novel and fascinating electrocatalysts.In this review,we focus on some recent advances in designing M@NG electrocatalysts for HER,OER and ORR through tuning electronic structure and activity of carbon active sites.We have summarized some facile and universal strategy for synthesizing various M@NG via direct annealing of metal-organic frameworks(MOFs).With elaborated MOFs precursor design,careful control over the nitrogen doping level,metal element types and alloy structure,the electronic structure of carbon active sites can be rationally tuned to optimize activity for different electrochemical reactions.We hope this review can provide new insights into the design of M@NG with high catalytic activity.
Yang YangJianwei SuPeng JiangJitang ChenLin HuQianwang Chen
This paper puts forward a novel artificial immune response algorithm for op-timal approximation of linear systems. A quaternion model of artificial immune response is proposed for engineering computing. The model abstracts four elements, namely, antigen, antibody, reaction rules among antibodies, and driving algorithm describing how the rules are applied to antibodies, to simulate the process of immune response. Some reaction rules including clonal selection rules, immunological memory rules and immune regulation rules are introduced. Using the theorem of Markov chain, it is proofed that the new model is convergent. The experimental study on the optimal approximation of a stable linear system and an unstable one show that the approximate models searched by the new model have better performance indices than those obtained by some existing algorithms including the differential evolution algorithm and the multi-agent genetic algorithm.
