To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient ...To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient treatment.Because clinical treatment requires a proton beam current in the∼nA range,nondestructive beam current monitors(BCMs)are preferred to minimize the degradation of beam quality.However,this poses significant challenges in accurately monitoring such extremely low beam intensities.This study proposes a cavity-type BCM equipped with a dielectric plate to reduce its dimensions and achieve sufficient measurement sensitivity for practical requirements.A prototype cavity BCM was fabricated,and off-line testing was performed using a metal wire to simulate the beam to study its performance.Both the simulation and experi-mental results showed that the cavity BCM could measure ultralow proton beam currents with a resolution up to 0.03 nA.展开更多
There is now little doubt that PEGylation is useful and is in widespread use because it provides a prolonged half-life,a higher stability and a lowerimmunogenicity[1].However,it is of concern that PEGylation may affec...There is now little doubt that PEGylation is useful and is in widespread use because it provides a prolonged half-life,a higher stability and a lowerimmunogenicity[1].However,it is of concern that PEGylation may affect the physicochemical and pharmacokinetic characteristics of protein-encapsulated liposome.Thus,we prepared the bovine serum albumin(BSA)-encapsulated liposome(BSA-liposome)with or without PEG and then compared their physicochemical and pharmacokinetic characteristics(Fig.1).BSA-liposomes were prepared by the thin-film hydration method.展开更多
It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work,the Au–O interactions in various surroundings were...It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work,the Au–O interactions in various surroundings were investigated by DFT calculations and compared with the Ag–O interactions. We have found the three points.First,only Au–O bond can be significantly strengthened by the linear O–Au–O structure. Second,the Au–O bond is always stronger than the Ag–O bond when the bonds are embedded in common surroundings. Third,the Au–O bond becomes weaker than the Ag–O bond when the number of neighboring Au atoms becomes large,because the Au–O interactions are suppressed by the presence of neighboring gold atoms. The origin of these three points can be attributed to wider spatial extension of d orbitals of gold,induced by strong relativistic effects. The strong relativistic effects make nanogold with smaller coordinate numbers highly active due to the ease in forming strong Au–O bonds,especially for the O–Au–O bond,whereas gold atoms in bulk with larger coordination numbers chemically inert due to the strong suppression by neighboring gold atoms destabilizing the O–Au–O bond.展开更多
The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate f...The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.展开更多
Currently, hepatitis B virus(HBV), upon attaching to human hepatocytes, is considered to interact first with heparan sulfate proteoglycan(HSPG) via an antigenic loop of HBV envelope S protein. Then, it is promptly tra...Currently, hepatitis B virus(HBV), upon attaching to human hepatocytes, is considered to interact first with heparan sulfate proteoglycan(HSPG) via an antigenic loop of HBV envelope S protein. Then, it is promptly transferred to the sodium taurocholate cotransporting polypeptide(NTCP) via the myristoylated N-terminal sequence of pre-S1 region(from Gly-2 to Gly-48, HBV genotype D), and it finally enters the cell by endocytosis. However, it is not clear how HSPG passes HBV to NTCP and how NTCP contributes to the cellular entry of HBV. Owing to the poor availability and the difficulty of manipulations, including fluorophore encapsulation, it has been nearly impossible to perform biochemical and cytochemical analyses using a substantial amount of HBV. A bio-nanocapsule(BNC), which is a hollow nanoparticle consisting of HBV envelope L protein, was efficiently synthesized in Saccharomyces cerevisiae. Since BNC could encapsulate payloads(drugs, genes, proteins) and specifically enter human hepatic cells utilizing HBV-derived infection machinery, it could be used as a model of HBV infection to elucidate the early infection machinery. Recently, it was demonstrated that the N-terminal sequence of pre-S1 region(from Asn-9 to Gly-24) possesses low p H-dependent fusogenic activity, which might play a crucial role in the endosomal escape of BNC payloads and in the uncoating process of HBV. In this minireview, we describe a model in which each domain of the HBV L protein contributes to attachment onto human hepatic cells through HSPG, initiation of endocytosis, interaction with NTCP in endosomes, and consequent provocation of membrane fusion followed by endosomal escape.展开更多
Over 70%of the treated contaminated water at the Fukushima Daiichi Nuclear Power Station contains radionuclides beyond the regulatory standard for discharge that need to be re-purified.Technetium-99(^(99)Tc),mainly in...Over 70%of the treated contaminated water at the Fukushima Daiichi Nuclear Power Station contains radionuclides beyond the regulatory standard for discharge that need to be re-purified.Technetium-99(^(99)Tc),mainly in the form of pertechnetate Tc(VII)O_(4)^(-),is one of the main sources of long-term radiotoxicity that jeopardizes the environment and human health.Herein,we used a series of dicationic pyridinium(DCP)derivative groups(–Py^(+)C_(n)H_(2n)N^(+)Me_(3),n=2,3,and 5)to modify commercial Reillex 425 resins containing tertiary pyridyl groups to improve the adsorption performance of rhenium(Re,an analog of radioactive Tc)and Tc.As the quaternary pyridinium and ammonium sites in one DCP group can adsorb ReO_(4)^(-) simultaneously,DCP-modified Reillex 425(Reillex-Cn)exhibited high maximum adsorption capacities for Re under neutral conditions.Adsorption capacities reached 344.8,416.7,and 588.2 mg g^(-)1 for Reillex 425-C2,Reillex 425-C3,and Reillex 425-C5,respectively.Intraparticle diffusion of ReO_(4)^(-)/TcO_(4)^(-) in Reillex 425-Cn was verified to be the rate-limiting step of adsorption.However,adsorption can be adjusted by the length of the alkyl spacers between the two positively charged N sites in DCP.–Py^(+)C_(2)H_(4)N^(+)Me_(3) significantly enhanced intraparticle diffusion compared to–Py^(+)C_(5)H_(10)N^(+)Me_(3).The two positive sites in–Py^(+)C_(2)H_(4)N^(+)Me_(3) would be laterally distributed,leading to a smaller steric hindrance for ReO_(4)–/TcO_(4)^(-) transport inside the microporous channels.Meanwhile,the longer alkyl spacers in–Py^(+)C_(5)H_(10)N^(+)Me_(3) formed hydrophobic microphases,repulsing the hydrated ReO_(4)–/TcO_(4)^(-) anions.Thus,the adsorptions of both ReO_(4)^(-) and TcO_(4)^(-) on Reillex 425-C2 were faster than those on Reillex 425-C5.Moreover,Reillex 425-Cn exhibited an exothermic nature,good selectivity,excellent reusability,and strong salinity tolerance.This study provides a simple strategy to enhance the Tc removal performance of adsorbents containing abundant micropores,which implies enormous environmental and economic benefits.展开更多
Transparent electrode based on silver nanowires(Ag NWs) emerges as an outstanding alternative of indium tin oxide film especially for flexible electronics. However, the conductivity of Ag NWs transparent electrode is ...Transparent electrode based on silver nanowires(Ag NWs) emerges as an outstanding alternative of indium tin oxide film especially for flexible electronics. However, the conductivity of Ag NWs transparent electrode is still dramatically limited by the contact resistance between nanowires at high transmittance. Polyvinylpyrrolidone(PVP) layer adsorbed on the nanowire surface acts as an electrically insulating barrier at wire–wire junctions, and some devastating post-treatment methods are proposed to reduce or eliminate PVP layer, which usually limit the application of the substrates susceptible to heat or pressure and burden the fabrication with high-cost, time-consuming, or inefficient processes. In this work, a simple and rapid pre-treatment washing method was proposed to reduce the thickness of PVP layer from 13.19 to0.96 nm and improve the contact between wires. Ag NW electrodes with sheet resistances of 15.6 and 204 X sq-1have been achieved at transmittances of 90 and 97.5 %, respectively. This method avoided any post-treatments and popularized the application of high-performance Ag NW transparent electrode on more substrates. The improved Ag NWs were successfully employed in a capacitive pressure sensor with high transparency, sensitivity, and reproducibility.展开更多
Ordered metal oxides superstructures have attracted much more attention in the fields of fuel generation and environmental purification owing to their unique physiochemical characteristics such as large surface area, ...Ordered metal oxides superstructures have attracted much more attention in the fields of fuel generation and environmental purification owing to their unique physiochemical characteristics such as large surface area, fine pore structure, efficient electronic mobility, and good stability. Very recently, TiOmesocrystals（TMCs） having superstructures self-assembled by TiOnanoparticle building blocks, are of considerable interest in current research and application ranging from UV to visible light attributed to their efficient charge separation and superior photocatalytic activity. In this review, we describe the common procedures to prepare unique TMCs and overview of recent developments of TMCs during last 3 years, especially the structure-related or electronic-effected mechanism in photocatalytic reaction. Further, we introduce the characterization and fundamental properties of modified TMCs by the means of single-particle fluorescence microscopy for unraveling the charge transport and photocatalytic properties of individual TMCs and time-resolved diffuse reflectance spectroscopy（TDR） for monitoring the charge transfer dynamics. Finally, various aspects on TMCs are discussed for the future developments of energy and environmental fields.展开更多
A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University.The laser pulse is used for excitation of the photocathode and for generation of white lig...A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University.The laser pulse is used for excitation of the photocathode and for generation of white light,which is used for analyzing light in the pulse radiolysis.展开更多
Van der Waals coupling with different stacking configurations can significantly affect the optical and electronic properties of ultrathin two-dimensional(2D)materials,which is an effective way to tune device performan...Van der Waals coupling with different stacking configurations can significantly affect the optical and electronic properties of ultrathin two-dimensional(2D)materials,which is an effective way to tune device performance.Herein,we report a salt-assisted chemical vapor deposition method for the synthesis of bilayer V-doped MoS_(2) with 2H and 3R phases,which are demonstrated by the second harmonic generation and scanning transmission electron microscopy.Notably,the mobility of the 3R phase V-doped MoS_(2) is 6.2%higher than that of the 2H phase.Through first-principles calculations,we further reveal that this particular behavior is attributed to the stronger interlayer coupling of 3R compared to the 2H stacking configuration.This research can be further generalized to other transition metal chalcogenides and will contribute to the development of electronic devices based on 2D materials in the future.展开更多
With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,t...With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,the foreseeable harsh operating environment such as heavy thermal-load or extremely temperature cycle required more reliable interconnection technology[4,7-9].展开更多
Pristine and Bi-doped lanthanum titanium oxide(La_(2)Ti_(2)O_(7))nanosheets have been synthesized as photocatalysts for overall solar water splitting.The surface hole trap is a critical factor that limits the photocat...Pristine and Bi-doped lanthanum titanium oxide(La_(2)Ti_(2)O_(7))nanosheets have been synthesized as photocatalysts for overall solar water splitting.The surface hole trap is a critical factor that limits the photocatalytic activity of pristine La_(2)Ti_(2)O_(7)-Deposition of cobalt phosphate(Co-Pi)and platinum(Pt)nanoparticles on La_(2)Ti_(2)O_(7) cannot remove the surface traps although they are essential for enabling the oxygen and hydrogen evolution reactions.It is interesting that doping bismuth(Bi)into La_(2)Ti_(2)O_(7) nanosheets has eliminated the surface traps due to surface enrichment of Bi.The Co-Pi/Bi-La_(2)Ti_(2)O_(7)/Pt nanosheets exhibit increasing photocatalytic activity toward overall water splitting with increasing the Bi-dopant level up to 5 at.%.Further increasing the Bi-dopant level leads to the formation of localized states above the valence band,leading to the lifetime reduction of photogenerated charge-carriers,and jeopardizing the photocatalytic activity.This work proposes an effective strategy to address the surface trapping and surface catalysis issues in the nanostructured metal oxide photocatalysts.展开更多
First principles density functional theory calculations have been performed for the chemisorption of formate adsorption on some metal surfaces. For the most stable adsorption site of short-bridge, the calculated forma...First principles density functional theory calculations have been performed for the chemisorption of formate adsorption on some metal surfaces. For the most stable adsorption site of short-bridge, the calculated formate adsorption energy follows the order of Au(110) < Ag(110) < Cu(110) < Pd(110) < Pt(110) < Ni(110) < Rh(110) < Fe(100) < Mo(100), and a clear linear correlation exists between the adsorption energy and the corresponding heat of formation of metal oxides. Moreover, it has been found that the formate adsorption energy for the transition metals can be correlated well with its d-band center (εd), and the IB Group metals can be described by the coupling matrix element square (Vad2).展开更多
Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heatt...Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heattreatment at about 200 ℃ which forms connecting junctions between AgNWs. Such a heating process is, however, one of the drawbacks of the fabrication of AgNW electrodes on heat-sensitive substrates. Here it has been demonstrated that the electrical conductivity of AgNW electrodes can be improved by mechanical pressing at 25 MPa for 5 s at room temperature. This simple process results in a low sheet resistance of 8.6 Ω/square and a transparency of 80.0%, equivalent to the properties of the AgNW electrodes heated at 200 ℃. This technique makes it possible to fabricate AgNW transparent electrodes on heat-sensitive substrates. The AgNW electrodes on poly（ethylene terephthalate） films exhibited high stability of their electrical conductivities against the repeated bending test. In addition, the surface roughness of the pressed AgNW electrodes is one-third of that of the heat-treated electrode because the AgNW junctions are mechanically compressed. As a result, an organic solar cell fabricated on the pressed AgNW electrodes exhibited a power conversion as much as those fabricated on indium tin oxide electrodes. These findings enable continuous roll-to-roll processing at room temperature, resulting in relatively simple, inexpensive, and scalable processing that is suitable for forthcoming technologies such as organic solar cells, flexible displays, and touch screens.展开更多
Silver nanowires （AgNWs） have emerged as a promising nanomaterial for next generation stretchable electronics. However, until now, the fabrication of AgNW- based components has been hampered by complex and time-cons...Silver nanowires （AgNWs） have emerged as a promising nanomaterial for next generation stretchable electronics. However, until now, the fabrication of AgNW- based components has been hampered by complex and time-consuming steps. Here, we introduce a facile, fast, and one-step methodology for the fabrication of highly conductive and stretchable AgNW/polyurethane （PU） composite electrodes based on a high-intensity pulsed light （HIPL） technique. HIPL simultaneously improved wire-wire junction conductivity and wire-substrate adhesion at room temperature and in air within 50 μs, omitting the complex transfer-curing-implanting process. Owing to the localized deformation of PU at interfaces with AgNWs, embedding of the nanowires was rapidly carried out without substantial substrate damage. The resulting electrode retained a low sheet resistance （high electrical conductivity） of 〈10 Ω/sq even under 100% strain, or after 1,000 continuous stretching-relaxation cycles, with a peak strain of 60%. The fabricated electrode has found immediate application as a sensor for motion detection. Furthermore, based on our electrode, a light emitting diode （LED） driven by integrated stretchable AgNW conductors has been fabricated. In conclusion, our present fabrication approach is fast, simple, scalable, and cost- efficient, making it a good candidate for a future roll-to-roll process.展开更多
Fe-Ni films with compositions of 73 wt% of Ni and 45 wt% of Ni were used as under bump metallization （UBM） in wafer level chip scale package, and their reliability was evaluated through electromigration （EM） test ...Fe-Ni films with compositions of 73 wt% of Ni and 45 wt% of Ni were used as under bump metallization （UBM） in wafer level chip scale package, and their reliability was evaluated through electromigration （EM） test compared with commercial Cu UBM. For Sn3.SAg0.7Cu（SAC）]Cu solder joints, voids had initiated at Cu cathode after 300 h and typical failures of depletion of Cu cathode and cracks were detected after 1000 h EM. While the SAC]Fe-Ni solder joints kept at a perfect condition without any failures after 1000 h EM. Moreover, the characteristic lifetime calculated by Weibull analysis for Fe-73Ni UBM （2121 h）, Fe-45Ni UBM （2340 h） were both over three folds to Cu UBM＇s （698 h）. The failure modes for Fe-Ni solder joints varied with the different growth behavior of intermetallic compounds （IMCs）, which can all be classified as the crack at the cathodic interface between solder and outer IMC layer. The atomic fluxes concerned cathode dissolution and crack initiation were analyzed. When Fe-Ni UBM was added, cathode dissolution was suppressed due to the low diffusivity of IMCs and opposite transferring direction to electron flow of Fe atoms. The smaller EM flux within solder material led a smaller vacancy flux in Fe-Ni solder joints, which can explain the delay of solder voids and cracks as well as the much longer lifetime under EM.展开更多
Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applicat...Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applications with PbTe for the development of high-performance IR photodetectors especially those working in the near-infrared regime.Although a great deal of effort had been made to prepare PbTe nanostructures for miniaturized detectors,it is difficult to synthesize high-quality two-dimensional(2D)PbTe crystals due to its rock-salt non-layered structure.Herein,a facile strategy for controllable synthesis of ultrathin crystalline PbTe nanosheets by van der Waals epitaxy is reported.With an optimized growth temperature,which determines the morphology transit from triangular pyramid islands to regular square 2D planars,PbTe nanosheets in lateral size of tens of microns with thickness down to~7 nm are achieved.Meanwhile,ultrasensitive near-infrared detectors(NIRDs)based on the as-grown 2D PbTe nanosheets have been demonstrated with an ultrahigh responsivity exceeding 3,847 A/W at the wavelength of 1,550 nm under room temperature.Our approach demonstrates that 2D PbTe nanosheets have great latent capacity of developing high-performance miniaturized IR optoelectronic devices.展开更多
In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of...In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of 300℃ in air atmospheric conditions.The relationship between the bonding strength and microstructure changes of sintered Ag under various bonding conditions was investigated in detail.The large-area bonded plate exhibits low porosity about 10%and low percentage of voids,which result in ultra-high bonding strength over 58 MPa.More importantly,the introduction of reducing agent formic acid(CH_(2)O_(2))and the low porosity successfully improve the anti-oxidation of novel Ag salt paste during sintering process,result in pure Cu-Ag-Cu bonding.The cross-section of the Ag joints was obtained to explain the bonding pattern,in which Cu was oxidized only at the edge of the sintering interface,and no Cu oxide generated in middle bonding section.The development of novel Ag salt paste successfully addresses the energy-intensive process and low bonding strength faced by large-scale sintering,which greatly promotes the high-temperature applications of power device.展开更多
Ionic gating is known as a powerful tool for investigation of electronic functionalities stemming from low voltage transistor operation to gate-induced electronic phase control including superconductivity.Two-dimensio...Ionic gating is known as a powerful tool for investigation of electronic functionalities stemming from low voltage transistor operation to gate-induced electronic phase control including superconductivity.Two-dimensional(2D)material is one of the archetypal channel materials which exhibit a variety of gate-induced phenomena.Nevertheless,the device simulations on such iongated transistor devices have never been reported,despite its importance for the future design of device structures.In this paper,we developed a drift-diffusion(DD)model on a 2D material,WSe2 monolayer,attached with an ionic liquid,and succeeded in simulating the transport properties,potential profile,carrier density distributions in the transistor configuration.展开更多
基金supported by the National Natural Science Foundation of China(No.12235005)the National Key Research and Development Program of China(No.2016YFC0105309).
文摘To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells,it is essential to accurately monitor the proton beam current in real time during patient treatment.Because clinical treatment requires a proton beam current in the∼nA range,nondestructive beam current monitors(BCMs)are preferred to minimize the degradation of beam quality.However,this poses significant challenges in accurately monitoring such extremely low beam intensities.This study proposes a cavity-type BCM equipped with a dielectric plate to reduce its dimensions and achieve sufficient measurement sensitivity for practical requirements.A prototype cavity BCM was fabricated,and off-line testing was performed using a metal wire to simulate the beam to study its performance.Both the simulation and experi-mental results showed that the cavity BCM could measure ultralow proton beam currents with a resolution up to 0.03 nA.
文摘There is now little doubt that PEGylation is useful and is in widespread use because it provides a prolonged half-life,a higher stability and a lowerimmunogenicity[1].However,it is of concern that PEGylation may affect the physicochemical and pharmacokinetic characteristics of protein-encapsulated liposome.Thus,we prepared the bovine serum albumin(BSA)-encapsulated liposome(BSA-liposome)with or without PEG and then compared their physicochemical and pharmacokinetic characteristics(Fig.1).BSA-liposomes were prepared by the thin-film hydration method.
基金supported by Grant-in-Aid for Specially Promoted Research Grant no.19001005 from the Ministry of Education,Culture,Sports,Science and Technology of Japan (MEXT)supported by the Management Expenses Grants for National Universities Corporations from MEXTJapan Science and Technology Agency (JST),Core Research for Evolutional Science and Technology (CREST)
文摘It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work,the Au–O interactions in various surroundings were investigated by DFT calculations and compared with the Ag–O interactions. We have found the three points.First,only Au–O bond can be significantly strengthened by the linear O–Au–O structure. Second,the Au–O bond is always stronger than the Ag–O bond when the bonds are embedded in common surroundings. Third,the Au–O bond becomes weaker than the Ag–O bond when the number of neighboring Au atoms becomes large,because the Au–O interactions are suppressed by the presence of neighboring gold atoms. The origin of these three points can be attributed to wider spatial extension of d orbitals of gold,induced by strong relativistic effects. The strong relativistic effects make nanogold with smaller coordinate numbers highly active due to the ease in forming strong Au–O bonds,especially for the O–Au–O bond,whereas gold atoms in bulk with larger coordination numbers chemically inert due to the strong suppression by neighboring gold atoms destabilizing the O–Au–O bond.
基金supported by the Scientific and Technological Development Project of the Beijing Education Committee(No.KZ201710005009)
文摘The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.
文摘Currently, hepatitis B virus(HBV), upon attaching to human hepatocytes, is considered to interact first with heparan sulfate proteoglycan(HSPG) via an antigenic loop of HBV envelope S protein. Then, it is promptly transferred to the sodium taurocholate cotransporting polypeptide(NTCP) via the myristoylated N-terminal sequence of pre-S1 region(from Gly-2 to Gly-48, HBV genotype D), and it finally enters the cell by endocytosis. However, it is not clear how HSPG passes HBV to NTCP and how NTCP contributes to the cellular entry of HBV. Owing to the poor availability and the difficulty of manipulations, including fluorophore encapsulation, it has been nearly impossible to perform biochemical and cytochemical analyses using a substantial amount of HBV. A bio-nanocapsule(BNC), which is a hollow nanoparticle consisting of HBV envelope L protein, was efficiently synthesized in Saccharomyces cerevisiae. Since BNC could encapsulate payloads(drugs, genes, proteins) and specifically enter human hepatic cells utilizing HBV-derived infection machinery, it could be used as a model of HBV infection to elucidate the early infection machinery. Recently, it was demonstrated that the N-terminal sequence of pre-S1 region(from Asn-9 to Gly-24) possesses low p H-dependent fusogenic activity, which might play a crucial role in the endosomal escape of BNC payloads and in the uncoating process of HBV. In this minireview, we describe a model in which each domain of the HBV L protein contributes to attachment onto human hepatic cells through HSPG, initiation of endocytosis, interaction with NTCP in endosomes, and consequent provocation of membrane fusion followed by endosomal escape.
基金supported by the National Natural Science Foundation of China(Nos.51803205,11775214,and 21790371)China Scholarship Council(No.201906345006).
文摘Over 70%of the treated contaminated water at the Fukushima Daiichi Nuclear Power Station contains radionuclides beyond the regulatory standard for discharge that need to be re-purified.Technetium-99(^(99)Tc),mainly in the form of pertechnetate Tc(VII)O_(4)^(-),is one of the main sources of long-term radiotoxicity that jeopardizes the environment and human health.Herein,we used a series of dicationic pyridinium(DCP)derivative groups(–Py^(+)C_(n)H_(2n)N^(+)Me_(3),n=2,3,and 5)to modify commercial Reillex 425 resins containing tertiary pyridyl groups to improve the adsorption performance of rhenium(Re,an analog of radioactive Tc)and Tc.As the quaternary pyridinium and ammonium sites in one DCP group can adsorb ReO_(4)^(-) simultaneously,DCP-modified Reillex 425(Reillex-Cn)exhibited high maximum adsorption capacities for Re under neutral conditions.Adsorption capacities reached 344.8,416.7,and 588.2 mg g^(-)1 for Reillex 425-C2,Reillex 425-C3,and Reillex 425-C5,respectively.Intraparticle diffusion of ReO_(4)^(-)/TcO_(4)^(-) in Reillex 425-Cn was verified to be the rate-limiting step of adsorption.However,adsorption can be adjusted by the length of the alkyl spacers between the two positively charged N sites in DCP.–Py^(+)C_(2)H_(4)N^(+)Me_(3) significantly enhanced intraparticle diffusion compared to–Py^(+)C_(5)H_(10)N^(+)Me_(3).The two positive sites in–Py^(+)C_(2)H_(4)N^(+)Me_(3) would be laterally distributed,leading to a smaller steric hindrance for ReO_(4)–/TcO_(4)^(-) transport inside the microporous channels.Meanwhile,the longer alkyl spacers in–Py^(+)C_(5)H_(10)N^(+)Me_(3) formed hydrophobic microphases,repulsing the hydrated ReO_(4)–/TcO_(4)^(-) anions.Thus,the adsorptions of both ReO_(4)^(-) and TcO_(4)^(-) on Reillex 425-C2 were faster than those on Reillex 425-C5.Moreover,Reillex 425-Cn exhibited an exothermic nature,good selectivity,excellent reusability,and strong salinity tolerance.This study provides a simple strategy to enhance the Tc removal performance of adsorbents containing abundant micropores,which implies enormous environmental and economic benefits.
基金partly supported by Showa Denko Co. Ltd, Grant-in-Aid for Scientific Research (Kaken S, 24226017)COI Stream Projectfinancial support from China Scholarship Council
文摘Transparent electrode based on silver nanowires(Ag NWs) emerges as an outstanding alternative of indium tin oxide film especially for flexible electronics. However, the conductivity of Ag NWs transparent electrode is still dramatically limited by the contact resistance between nanowires at high transmittance. Polyvinylpyrrolidone(PVP) layer adsorbed on the nanowire surface acts as an electrically insulating barrier at wire–wire junctions, and some devastating post-treatment methods are proposed to reduce or eliminate PVP layer, which usually limit the application of the substrates susceptible to heat or pressure and burden the fabrication with high-cost, time-consuming, or inefficient processes. In this work, a simple and rapid pre-treatment washing method was proposed to reduce the thickness of PVP layer from 13.19 to0.96 nm and improve the contact between wires. Ag NW electrodes with sheet resistances of 15.6 and 204 X sq-1have been achieved at transmittances of 90 and 97.5 %, respectively. This method avoided any post-treatments and popularized the application of high-performance Ag NW transparent electrode on more substrates. The improved Ag NWs were successfully employed in a capacitive pressure sensor with high transparency, sensitivity, and reproducibility.
基金supported by a grant-in-aid for Scientific Research (Project 25220806 and others) from the Ministry of Education,Culture,Sports,Science and Technology (MEXT) of the Japanese Government
文摘Ordered metal oxides superstructures have attracted much more attention in the fields of fuel generation and environmental purification owing to their unique physiochemical characteristics such as large surface area, fine pore structure, efficient electronic mobility, and good stability. Very recently, TiOmesocrystals（TMCs） having superstructures self-assembled by TiOnanoparticle building blocks, are of considerable interest in current research and application ranging from UV to visible light attributed to their efficient charge separation and superior photocatalytic activity. In this review, we describe the common procedures to prepare unique TMCs and overview of recent developments of TMCs during last 3 years, especially the structure-related or electronic-effected mechanism in photocatalytic reaction. Further, we introduce the characterization and fundamental properties of modified TMCs by the means of single-particle fluorescence microscopy for unraveling the charge transport and photocatalytic properties of individual TMCs and time-resolved diffuse reflectance spectroscopy（TDR） for monitoring the charge transfer dynamics. Finally, various aspects on TMCs are discussed for the future developments of energy and environmental fields.
文摘A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University.The laser pulse is used for excitation of the photocathode and for generation of white light,which is used for analyzing light in the pulse radiolysis.
基金financially supported by the National Natural Science Foundation of China (Nos.62174013 and92265111)the Funding Program of Beijing Institute of Technology (Nos.3180012212214 and 3180023012204)。
文摘Van der Waals coupling with different stacking configurations can significantly affect the optical and electronic properties of ultrathin two-dimensional(2D)materials,which is an effective way to tune device performance.Herein,we report a salt-assisted chemical vapor deposition method for the synthesis of bilayer V-doped MoS_(2) with 2H and 3R phases,which are demonstrated by the second harmonic generation and scanning transmission electron microscopy.Notably,the mobility of the 3R phase V-doped MoS_(2) is 6.2%higher than that of the 2H phase.Through first-principles calculations,we further reveal that this particular behavior is attributed to the stronger interlayer coupling of 3R compared to the 2H stacking configuration.This research can be further generalized to other transition metal chalcogenides and will contribute to the development of electronic devices based on 2D materials in the future.
文摘With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,the foreseeable harsh operating environment such as heavy thermal-load or extremely temperature cycle required more reliable interconnection technology[4,7-9].
基金supported by the National Natural Science Foundation of China(Nos.51972010 and 51472013)the Natural Science Foundation of Jiangsu Province(Youth Fund,Nos.BK20190640 and BK20190641)the Fundamental Research Funds for the Central Universities(No.2019XKQYMS11)。
文摘Pristine and Bi-doped lanthanum titanium oxide(La_(2)Ti_(2)O_(7))nanosheets have been synthesized as photocatalysts for overall solar water splitting.The surface hole trap is a critical factor that limits the photocatalytic activity of pristine La_(2)Ti_(2)O_(7)-Deposition of cobalt phosphate(Co-Pi)and platinum(Pt)nanoparticles on La_(2)Ti_(2)O_(7) cannot remove the surface traps although they are essential for enabling the oxygen and hydrogen evolution reactions.It is interesting that doping bismuth(Bi)into La_(2)Ti_(2)O_(7) nanosheets has eliminated the surface traps due to surface enrichment of Bi.The Co-Pi/Bi-La_(2)Ti_(2)O_(7)/Pt nanosheets exhibit increasing photocatalytic activity toward overall water splitting with increasing the Bi-dopant level up to 5 at.%.Further increasing the Bi-dopant level leads to the formation of localized states above the valence band,leading to the lifetime reduction of photogenerated charge-carriers,and jeopardizing the photocatalytic activity.This work proposes an effective strategy to address the surface trapping and surface catalysis issues in the nanostructured metal oxide photocatalysts.
基金Supported by the National Natural Science Foundation of China (Grants Nos. 20273034 & 20673063)
文摘First principles density functional theory calculations have been performed for the chemisorption of formate adsorption on some metal surfaces. For the most stable adsorption site of short-bridge, the calculated formate adsorption energy follows the order of Au(110) < Ag(110) < Cu(110) < Pd(110) < Pt(110) < Ni(110) < Rh(110) < Fe(100) < Mo(100), and a clear linear correlation exists between the adsorption energy and the corresponding heat of formation of metal oxides. Moreover, it has been found that the formate adsorption energy for the transition metals can be correlated well with its d-band center (εd), and the IB Group metals can be described by the coupling matrix element square (Vad2).
文摘Silver nanowires （AgNWs） surrounded by insulating poly（vinylpyrrolidone） have been synthesized by a polyol process and employed as transparent electrodes. The AgNW transparent electrodes can be fabricated by heattreatment at about 200 ℃ which forms connecting junctions between AgNWs. Such a heating process is, however, one of the drawbacks of the fabrication of AgNW electrodes on heat-sensitive substrates. Here it has been demonstrated that the electrical conductivity of AgNW electrodes can be improved by mechanical pressing at 25 MPa for 5 s at room temperature. This simple process results in a low sheet resistance of 8.6 Ω/square and a transparency of 80.0%, equivalent to the properties of the AgNW electrodes heated at 200 ℃. This technique makes it possible to fabricate AgNW transparent electrodes on heat-sensitive substrates. The AgNW electrodes on poly（ethylene terephthalate） films exhibited high stability of their electrical conductivities against the repeated bending test. In addition, the surface roughness of the pressed AgNW electrodes is one-third of that of the heat-treated electrode because the AgNW junctions are mechanically compressed. As a result, an organic solar cell fabricated on the pressed AgNW electrodes exhibited a power conversion as much as those fabricated on indium tin oxide electrodes. These findings enable continuous roll-to-roll processing at room temperature, resulting in relatively simple, inexpensive, and scalable processing that is suitable for forthcoming technologies such as organic solar cells, flexible displays, and touch screens.
文摘Silver nanowires （AgNWs） have emerged as a promising nanomaterial for next generation stretchable electronics. However, until now, the fabrication of AgNW- based components has been hampered by complex and time-consuming steps. Here, we introduce a facile, fast, and one-step methodology for the fabrication of highly conductive and stretchable AgNW/polyurethane （PU） composite electrodes based on a high-intensity pulsed light （HIPL） technique. HIPL simultaneously improved wire-wire junction conductivity and wire-substrate adhesion at room temperature and in air within 50 μs, omitting the complex transfer-curing-implanting process. Owing to the localized deformation of PU at interfaces with AgNWs, embedding of the nanowires was rapidly carried out without substantial substrate damage. The resulting electrode retained a low sheet resistance （high electrical conductivity） of 〈10 Ω/sq even under 100% strain, or after 1,000 continuous stretching-relaxation cycles, with a peak strain of 60%. The fabricated electrode has found immediate application as a sensor for motion detection. Furthermore, based on our electrode, a light emitting diode （LED） driven by integrated stretchable AgNW conductors has been fabricated. In conclusion, our present fabrication approach is fast, simple, scalable, and cost- efficient, making it a good candidate for a future roll-to-roll process.
基金financially supported by the National Key Research and Development Program of China(Grant No.2017YFB0305501)the National Natural Science Foundation of China(Grant Nos.51401218 and 51171191)the Osaka University Visiting Scholar Program(Grant No.J135104902)
文摘Fe-Ni films with compositions of 73 wt% of Ni and 45 wt% of Ni were used as under bump metallization （UBM） in wafer level chip scale package, and their reliability was evaluated through electromigration （EM） test compared with commercial Cu UBM. For Sn3.SAg0.7Cu（SAC）]Cu solder joints, voids had initiated at Cu cathode after 300 h and typical failures of depletion of Cu cathode and cracks were detected after 1000 h EM. While the SAC]Fe-Ni solder joints kept at a perfect condition without any failures after 1000 h EM. Moreover, the characteristic lifetime calculated by Weibull analysis for Fe-73Ni UBM （2121 h）, Fe-45Ni UBM （2340 h） were both over three folds to Cu UBM＇s （698 h）. The failure modes for Fe-Ni solder joints varied with the different growth behavior of intermetallic compounds （IMCs）, which can all be classified as the crack at the cathodic interface between solder and outer IMC layer. The atomic fluxes concerned cathode dissolution and crack initiation were analyzed. When Fe-Ni UBM was added, cathode dissolution was suppressed due to the low diffusivity of IMCs and opposite transferring direction to electron flow of Fe atoms. The smaller EM flux within solder material led a smaller vacancy flux in Fe-Ni solder joints, which can explain the delay of solder voids and cracks as well as the much longer lifetime under EM.
基金the National Natural Science Foundation of China(Nos.61875223,61922082 and 61927813)the Natural Science Foundation of Hainan Province(No.117111)。
文摘Lead telluride(PbTe)is one of the reliable candidates for infrared(IR)optoelectronics with optimum band-gap as well as excellent photoelectric properties.Great interests had been paid on the growth and device applications with PbTe for the development of high-performance IR photodetectors especially those working in the near-infrared regime.Although a great deal of effort had been made to prepare PbTe nanostructures for miniaturized detectors,it is difficult to synthesize high-quality two-dimensional(2D)PbTe crystals due to its rock-salt non-layered structure.Herein,a facile strategy for controllable synthesis of ultrathin crystalline PbTe nanosheets by van der Waals epitaxy is reported.With an optimized growth temperature,which determines the morphology transit from triangular pyramid islands to regular square 2D planars,PbTe nanosheets in lateral size of tens of microns with thickness down to~7 nm are achieved.Meanwhile,ultrasensitive near-infrared detectors(NIRDs)based on the as-grown 2D PbTe nanosheets have been demonstrated with an ultrahigh responsivity exceeding 3,847 A/W at the wavelength of 1,550 nm under room temperature.Our approach demonstrates that 2D PbTe nanosheets have great latent capacity of developing high-performance miniaturized IR optoelectronic devices.
基金partly supported a project (JPNP14004) commissioned by the New Energy and Industrial Technology Development Organization (NEDO)the supporting from TOPPAN FORMS CO.,LTD,Japan
文摘In this paper,by proposing a novel and low-cost Ag salt paste,a robustly and large-area(35×35 mm^(2))bare Cu to Cu bonding was realized under a low sintering pressure of 0.8 MPa and a low sintering temperature of 300℃ in air atmospheric conditions.The relationship between the bonding strength and microstructure changes of sintered Ag under various bonding conditions was investigated in detail.The large-area bonded plate exhibits low porosity about 10%and low percentage of voids,which result in ultra-high bonding strength over 58 MPa.More importantly,the introduction of reducing agent formic acid(CH_(2)O_(2))and the low porosity successfully improve the anti-oxidation of novel Ag salt paste during sintering process,result in pure Cu-Ag-Cu bonding.The cross-section of the Ag joints was obtained to explain the bonding pattern,in which Cu was oxidized only at the edge of the sintering interface,and no Cu oxide generated in middle bonding section.The development of novel Ag salt paste successfully addresses the energy-intensive process and low bonding strength faced by large-scale sintering,which greatly promotes the high-temperature applications of power device.
基金This research was supported by Grant-in-Aid for Scientific Research(S)(no.19H05602)Grant-in-Aid for Scientific Research(C)(no.19K05201)from JSPS.
文摘Ionic gating is known as a powerful tool for investigation of electronic functionalities stemming from low voltage transistor operation to gate-induced electronic phase control including superconductivity.Two-dimensional(2D)material is one of the archetypal channel materials which exhibit a variety of gate-induced phenomena.Nevertheless,the device simulations on such iongated transistor devices have never been reported,despite its importance for the future design of device structures.In this paper,we developed a drift-diffusion(DD)model on a 2D material,WSe2 monolayer,attached with an ionic liquid,and succeeded in simulating the transport properties,potential profile,carrier density distributions in the transistor configuration.
