Stable Cycling of All-Solid-State Lithium Metal Batteries Enabled by Salt Engineering of PEO-Based Polymer Electrolytes

Poly(ethylene oxide)(PEO)-based polymer electrolytes show the prospect in all-solid-state lithium metal batteries;however,they present limitations of low room-temperature ionic conductivity,and interfacial incompatibility with high voltage cathodes.Therefore,a salt engineering of 1,1,2,2,3,3-hexafluoropropane-1,3-disulfonimide lithium salt(LiHFDF)/LiTFSI system was developed in PEO-based electrolyte,demonstrating to effectively regulate Li ion transport and improve the interfacial stability under high voltage.We show,by manipulating the interaction between PEO matrix and TFSI^(-)-HFDF^(-),the optimized solid-state polymer electrolyte achieves maximum Li+conduction of 1.24×10^(-4)S cm^(-1)at 40℃,which is almost 3 times of the baseline.Also,the optimized polymer electrolyte demonstrates outstanding stable cycling in the LiFePO_(4)/Li and LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li(3.0-4.4 V,200 cycles)based all-solid-state lithium batteries at 40℃.

Two innovative equivalent statements of the third law of thermodynamics

It is found from textbooks and literature that there are three different statements for the third law of thermodynamics,i.e., the Nernst theorem, the unattainability statement of absolute zero temperature, and the heat capacity statement. It is pointed out that such three statements correspond to three thermodynamic parameters, which are, respectively, the entropy,temperature, and heat capacity, and can be obtained by extrapolating the experimental results of different parameters at ultralow temperatures to absolute zero. It is expounded that because there is no need for additional assumptions in the derivation of the Nernst equation, the Nernst theorem should be renamed as the Nernst statement. Moreover, it is proved that both the Nernst statement and the heat capacity statement are mutually deducible and equivalent, while the unattainability of absolute zero temperature is only a corollary of the Nernst statement or the heat capacity statement so that it is unsuitably referred to as one statement of the third law of thermodynamics. The conclusion is that the Nernst statement and the heat capacity statement are two equivalent statements of the third law of thermodynamics.

Core-Shell Semiconductor-Graphene Nanoarchitectures for Efficient Photocatalysis:State of the Art and Perspectives

Semiconductor photocatalysis holds great promise for renewable energy generation and environment remediation,but generally suffers from the serious drawbacks on light absorption,charge generation and transport,and structural stability that limit the performance.The core-shell semiconductorgraphene(CSSG)nanoarchitectures may address these issues due to their unique structures with exceptional physical and chemical properties.This review explores recent advances of the CSSG nanoarchitectures in the photocatalytic performance.It starts with the classification of the CSSG nanoarchitectures by the dimensionality.Then,the construction methods under internal and external driving forces were introduced and compared with each other.Afterward,the physicochemical properties and photocatalytic applications of these nanoarchitectures were discussed,with a focus on their role in photocatalysis.It ends with a summary and some perspectives on future development of the CSSG nanoarchitectures toward highly efficient photocatalysts with extensive application.By harnessing the synergistic capabilities of the CSSG architectures,we aim to address pressing environmental and energy challenges and drive scientific progress in these fields.

Stable Cycling of All-Solid-State Lithium Batteries Enabled by Cyano-Molecular Diamond Improved Polymer Electrolytes

The interfacial instability of the poly(ethylene oxide)(PEO)-based electrolytes impedes the long-term cycling and further application of all-solid-state lithium metal batter-ies.In this work,we have shown an effective additive 1-adaman-tanecarbonitrile,which con-tributes to the excellent per-formance of the poly(ethylene oxide)-based electrolytes.Owing to the strong interaction of the 1-Adamantanecarboni-trile to the polymer matrix and anions,the coordination of the Li^(+)-EO is weakened,and the binding effect of anions is strengthened,thereby improving the Li^(+)conductivity and the electrochemical stability.The diamond building block on the surface of the lithium anode can sup-press the growth of lithium dendrites.Importantly,the 1-Adamantanecarbonitrile also regulates the formation of LiF in the solid electrolyte interface and cathode electrolyte interface,which contributes to the interfacial stability(especially at high voltages)and protects the electrodes,enabling all-solid-state batteries to cycle at high voltages for long periods of time.Therefore,the Li/Li symmetric cell undergoes long-term lithium plating/stripping for more than 2000 h.1-Adamantanecarbonitrile-poly(ethylene oxide)-based LFP/Li and 4.3 V Ni_(0.8)Mn_(0.1)Co_(0.1)O_(2)/Li all-solid-state batteries achieved stable cycles for 1000 times,with capacity retention rates reaching 85%and 80%,respectively.

Mutation in a non-force-bearing region of protein L influences force-dependent unfolding behavior

Single-molecule magnetic tweezers(MTs) have revealed multiple transition barriers along the unfolding pathway of several two-state proteins, such as GB1 and Csp. In this study, we utilized MTs to measure the force-dependent folding and unfolding rates of both protein L(PLWT) and its Y47W mutant(PLY47W) where the mutation point is not at the force-bearing β-strands. The measurements were conducted within a force range of 3–120 pN. Notably, the unfolding rates of both PLWT and PWY47W exhibit distinct force sensitivities below 50 pN and above 60 pN, implying a two-barrier free energy landscape. Both PLWT and PLY47W share the same force-dependent folding rate and the same transition barriers,but the unfolding rate of PLY47W is faster than that of PLWT. Our finding demonstrates that the residue outside of the force-bearing region will also affect the force-induced unfolding dynamics.

Influence of shale reservoir properties on shale oil mobility and its mechanism

Given the tremendous potential for continental shale oil in China,many oilfields in the central and eastern parts of the country are involved in the exploration and development of shale oil resources.Besides engineering factors,shale oil mobility is the key to determining its commercial viability.This study explores the Hetaoyuan Formation in the Biyang Depression as an example to determine the influence of reservoir properties on the movable oil volume and its mechanisms.Multiple techniques were used,including displacement nuclear magnetic resonance(NMR),low-temperature nitrogen adsorption(LTNA),X-ray diffraction(XRD)bulk mineral analysis,and scanning electron microscopy(SEM),and the results suggest that large average pore diameter,high throat to pore ratio,single pore morphology,and small specific surface area can weaken the boundary layer effect and reduce the amount of adsorbed oil.Our observations reveal that compared to the dissolution pores and intergranular pores in brittle minerals,the intercrystalline pores in terrigenous clastic clay minerals are more affected by compaction.Furthermore,authigenic clay minerals notably block the intergranular pores in the interbedded sandstones.Clay minerals are identified as the main contributor to the specific surface area,with high clay mineral content enhancing the pore heterogeneity of the reservoir.Thus,positive shale oil mobility occurs in shale with a weak boundary layer effect,which is attributed to the high brittle mineral content,large average pore diameter,small specific surface area,single pore morphology,and reservoir homogeneity.

PRELIMINARY STUDY OF FEASIBILITY OF WHOLE BODY DIFFUSION WEIGHTED IMAGING IN DIAGNOSIS OF METASTASIS OF TUMOR

Objective To evaluate the feasibility of whole body diffusion weighted imaging (DWI) in the diagnosis of metastatic tumor. Methods Fifty-six patients (40 males and 16 females, age ranging from 29 to 84 years with a mean age of 57 years) with a variety of primary tumors were investigated by whole body DWI combined with computed tomography (CT) and/or conventional magnetic resonance imaging (MRI) scans. Twelve patients underwent positron emission tomography. The final diagnosis was made on the basis of CT or high resolution CT result for lung lesion and MRI or CT result for skull, abdomen and other parts. All tumors were classified into four groups by their diameter: below 1.0 cm, 1.0-1.9 cm, 2.0-2.9 cm, and above 3.0 cm. The sensitivity and specificity of whole body DWI in the detection of metastatic tumor were analyzed. Results The sensitivities of whole body DWI for screening metastasis of the four groups were 38%, 75%, 97%, and 100%, respectively. Whole body DWI showed the highest sensitivity and specificity for detecting metastasis of the skeletal system. It was difficult to find metastatic tumor whose diameter was below 1.0 cm, or lymph nodes located in the pelvis with diameter below 2.0 cm. Conclusions Whole body DWI is a promising method in the diagnosis of metastastic tumors. With the perfection of scanning parameter, whole body DWI should be a new effective whole body technique for tumor detection.

Structural Stabilities and Electronic Structures of Ga Atomic Chains

The structural stabilities and electronic structures of Ga atomic chains are studied by the first-principles plane wave pseudopotential method based on the density functional theory. The present calculations show that gallium can form planar chains in linear-, zigzag- and ladder-form one-dimensional structures. The most stable one among the studied structures is the zigzag chain with a unit cell rather close to equilateral triangles with four nearest neighbors, and all the other structures are metastable. The relative structural stability, the energy bands and the charge densities are discussed based on the ab initio calculations and the Jahn-Teller effect.

Laser lift-off technique and the re-utilization of GaN-based LED films grown on sapphire substrate

A thin GaN LED film, grown on 2-inch-diameter sapphire substrates, is separated by laser lift-off. Atom force microscopy （AFM） and the double-crystal X-ray diffraction （XRD） have been employed to characterize the performance of Gan before and after the lift-off process. It is demonstrated that the separation and transfer processes do not alter the crystal quality of the GaN films obviously. InGaN/GaN multi-quantum-wells （MQW＇s） structure is grown on the separated sapphire substrate later and is compared with that grown on the conventional substmte under the same condition by using PL and XRD spectrum.

Quasiparticle Band Structure of BaS

We calculate the band structure of BaS using the local density approximation and the GW approximation （ G WA ）, i.e. in combination of the Green function G and the screened Coulomb interaction W, The Ba 4d states are treated as valence states. We find that BaS is a direct band-gap semiconductor, The result shows that the GWA band gap （Eg-Gw = 3.921 eV） agrees excellently with the experimental result （Eg-EXPT = 3.88 eV or 3.9eV）.

Design and fabrication of 10-kV silicon–carbide p-channel IGBTs with hexagonal cells and step space modulated junction termination extension

10-kV 4 H–SiC p-channel insulated gate bipolar transistors(IGBTs) are designed, fabricated, and characterized in this paper. The IGBTs have an active area of 2.25 mm^2 with a die size of 3 mm× 3 mm. A step space modulated junction termination extension(SSM-JTE) structure is introduced and fabricated to improve the blocking performance of the IGBTs.The SiC p-channel IGBTs with SSM-JTE termination exhibit a leakage current of only 50 nA at-10 kV. To improve the on-state characteristics of SiC IGBTs, the hexagonal cell(H-cell) structure is designed and compared with the conventional interdigital cell(I-cell) structure. At an on-state current of 50 A/cm^2, the voltage drops of I-cell IGBT and H-cell IGBT are10.1 V and 8.3 V respectively. Meanwhile, on the assumption that the package power density is 300 W/cm^2, the maximum permissible current densities of the I-cell IGBT and H-cell IGBT are determined to be 34.2 A/cm^2 and 38.9 A/cm^2 with forward voltage drops of 8.8 V and 7.8 V, respectively. The differential specific on-resistance of I-cell structure and H-cell structure IGBT are 72.36 m?·cm^2 and 56.92 m?·cm^2, respectively. These results demonstrate that H-cell structure silicon carbide IGBT with SSM-JTE is a promising candidate for high power applications.

Valence Offsets of Three Series of Alloy Heterojunctions

Electron structure of three series of alloy heterojunctions(GaAs)_(x)(Ge_(2))_(1-x)/Ge,(AlAs)_(x)(Ge2)_(1-x)/Ge and Al_(x)G_(1-x)As/Ge are calculated by linear muffin-tin orbital method with atomic-sphere approximation using the average-bond-energy theory in conjunction with a cluster expansion method.The results indicate the variations ofΔE_(v)(x)at heterojunctions(GeAs)_(x)(Ge2)_(1-x)/Ge and(AlAs)_(x)(Ge2)_(1-x)/Ge are nonlinear,which are very different from that of Al_(x)Ga_(1-x)As/Ge.

Influence of barrier thickness on the structural and optical properties of InGaN/GaN multiple quantum wells

The structural and optical properties of InGaN/GaN multiple quantum wells （MQWs） with different barrier thick-nesses are studied by means of high resolution X-ray diffraction （HRXRD）, a cross-sectional transmission electron mi-croscope （TEM）, and temperature-dependent photoluminescence （PL） measurements. HRXRD and cross-sectional TEM measurements show that the interfaces between wells and barriers are abrupt and the entire MQW region has good periodic- ity for all three samples. As the barrier thickness is increased, the temperature of the turning point from blueshift to redshift of the S-shaped temperature-dependent PL peak energy increases monotonously, which indicates that the localization po- tentials due to In-rich clusters is deeper. From the Arrhenius plot of the normalized integrated PL intensity, it is found that there are two kinds of nonradiative recombination processes accounting for the thermal quenching of photoluminescence, and the corresponding activation energy （or the localization potential） increases with the increase of the barrier thickness. The dependence on barrier thickness is attributed to the redistribution of In-rich clusters during the growth of barrier layers, i.e., clusters with lower In contents aggregate into clusters with higher In contents.

Equilibrium folding and unfolding dynamics to reveal detailed free energy landscape of src SH3 protein by magnetic tweezers

Src SH3 protein domain is a typical two-state protein which has been confirmed by research of denaturant-induced unfolding dynamics.Force spectroscopy experiments by optical tweezers and atomic force microscopy have measured the force-dependent unfolding rates with different kinds of pulling geometry.However,the equilibrium folding and unfolding dynamics at constant forces has not been reported.Here,using stable magnetic tweezers,we performed equilibrium folding and unfolding dynamic measurement and force-jump measurement of src SH3 domain with tethering points at its N-and C-termini.From the obtained force-dependent transition rates,a detailed two-state free energy landscape of src SH3 protein is constructed with quantitative information of folding free energy,transition state barrier height and position,which exemplifies the capability of magnetic tweezers to study protein folding and unfolding dynamics.

Enhancement of thermal rectification by asymmetry engineering of thermal conductivity and geometric structure for multi-segment thermal rectifier

Thermal rectification is an exotic thermal transport phenomenon,an analog to electrical rectification,in which heat flux along one direction is larger than that in the other direction and is of significant interest in electronic device applications.However,achieving high thermal rectification efficiency or rectification ratio is still a scientific challenge.In this work,we performed a systematic simulation of thermal rectification by considering both efforts of thermal conductivity asymmetry and geometrical asymmetry in a multi-segment thermal rectifier.It is found that the high asymmetry of thermal conductivity and the asymmetry of the geometric structure of multi-segment thermal rectifiers can significantly enhance the thermal rectification,and the combination of both thermal conductivity asymmetry and geometrical asymmetry can further improve thermal rectification efficiency.This work suggests a possible way for improving thermal rectification devices by asymmetry engineering.

Structural optimization and segregation behavior of quaternary alloy nanoparticles based on simulated annealing algorithm

Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.

Direct Observation of NN Pairs Transfer in GaP1-xNx （x=0.12%）

Time-resolved photoluminescence （TRPL） was applied to investigate the transient process in GaP1-xNx （x = 0.12%） alloy. The filling, transferring and decay processes among nitrogen pairs are directly observed. The NN4 pair, either not present or only a small obscure peak under a proper excitation condition in the steady-state photoluminescence spectrum, is well resolved by TRPL.

Tuning Properties of External Cavity Violet Semiconductor Laser

A tunable grating-coupled external cavity(EC)laser is realized by employing a GaN-based laser diode as the gain device.A tuning range of 4.47 nm from 403.82 to 408.29 nm is achieved.Detailed investigations reveal that the injection current strongly influences the performance of the EC laser.Below the free-running lasing threshold,EC laser works stably.While above the free-running lasing threshold,a Fabry–Pérot(F-P)resonance peak in the emission spectrum and a smooth kink in the output power-injection current characteristic curve are observed,suggesting the competition between the inner F-P cavity resonance and EC resonance.Furthermore,the tuning range is found to be asymmetric and occurs predominantly on the longer wavelength side.This is interpreted in terms of the asymmetric gain distribution of GaN-based quantum well material.

Blind source separation of multichannel electroencephalogram based on wavelet transform and ICA

Combination of the wavelet transform and independent component analysis （ICA） was employed for blind source separation （BSS） of multichannel electroencephalogram （EEG）. After denoising the original signals by discrete wavelet transform, high frequency components of some noises and artifacts were removed from the original signals. The denoised signals were reconstructed again for the purpose of ICA, such that the drawback that ICA cannot distinguish noises from source signals can be overcome effectively. The practical processing results showed that this method is an effective way to BSS of multichannel EEG. The method is actually a combination of wavelet transform with adaptive neural network, so it is also useful for BBS of other complex signals.

Luminescence Properties of Ce^(3+)∶YAG Single Crystal Scintillator under Vacuum Ultraviolet Excitation

Ce (3+) doped Y_3Al_5O_(12) (Ce (3+)∶YAG) single crystal is an good scintillator due to its excellent thermal,mechanic and scintillant performances. In this paper,its vacuum ultraviolet and fluorescence spectra using the synchrotron radiation as the excitation source was studied. The ultraviolet-visible excitation and absorption spectra of Ce (3+)∶YAG were also measured. The excitation energy transfer process and the luminescent differences under direct excitation into the 5d bands of Ce (3+) and excitation of valence band in Ce (3+)∶YAG scintillator were studied.