We demonstrate a passively Q-switched Yb：LSO laser based on tungsten disulphide （WS2） saturable absorber op- erating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating me...We demonstrate a passively Q-switched Yb：LSO laser based on tungsten disulphide （WS2） saturable absorber op- erating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 gs with a repetition rate of 76.9 kHz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 mW, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS2 nanoplatelets.展开更多
Lithium-ion batteries(LIBs)are excellent electrochemical energy sources,albeit with existing challenges,including high costs and safety concerns.Magnesium-ion batteries(MIBs)are one of the potential alternatives.Howev...Lithium-ion batteries(LIBs)are excellent electrochemical energy sources,albeit with existing challenges,including high costs and safety concerns.Magnesium-ion batteries(MIBs)are one of the potential alternatives.However,the performance of MIBs is poor due to their sluggish solid-state Mg^(2+) diffusion kinetics and severe electrode polarizability.Rechargeable magnesium-ion/lithium-ion(Mg^(2+)/Li^(+))hybrid batteries(MLHBs)with Mg^(2+) and Li+as the charge carriers create a synergy between LIBs and MIBs with significantly improved charge transport kinetics and reliable safety features.However,MLHBs are yet to reach a reasonable electrochemical performance as expected.This work reports a composite electrode material with highly defective two-dimensional(2D)tin sulphide nanosheets(SnS_(x))encapsulated in three-dimensional(3D)holey graphene foams(HGF)(SnS_(x)/HGF),which exhibits a specific capacity as high as 600 mAh g^(−1) at 50 mA g^(−1) and a compelling specific energy density of~330 Wh kg^(−1).The excellent electrochemical performance surpasses previously reported hybrid battery systems based on intercalation-type cathode materials under comparable conditions.The role played by the defects in the SnS_(x)/HGF composite is studied to understand the origin of the observed excellent electrochemical performance.It is found that it is closely related to the defect structure in SnS_(x),which offers percolation pathways for efficient ion transport and increased internal surface area assessable to the charge carriers.The defective sites also absorb structural stress caused by Mg^(2+) and Li+insertion.This work is an important step towards realizing high-capacity cathode materials with fast charge transport kinetics for hybrid batteries.展开更多
A novel disulphide derivatised deuteroporphyrin 2,7,12,18-tetramethyl-13,17-（propionylaminoethyldithioethyl amino-formy-lethyl） -29,34-bis-（methoxyformyl）porphyrin（PDTEP,3） and its cobalt（Ⅱ） complex（Co（II）...A novel disulphide derivatised deuteroporphyrin 2,7,12,18-tetramethyl-13,17-（propionylaminoethyldithioethyl amino-formy-lethyl） -29,34-bis-（methoxyformyl）porphyrin（PDTEP,3） and its cobalt（Ⅱ） complex（Co（II）PDTEP,4） were conveniently synthesized. The disulphide functional group of 4 allowed its stable immobilization on gold electrodes.The modified electrode was characterized by IR and confirmed electrochemically and showed good stability and catalytic activity toward the electro-catalyzed reduction of hydrogen peroxide.展开更多
A novel thiol-derivative porphyrin[2,7,12,18-tetramethyl-13,17-di（3-disulfidepropyl）porphyrin]bearing the symmetrical disulphide bond and its metal complexes have been successfully prepared by means of modification ...A novel thiol-derivative porphyrin[2,7,12,18-tetramethyl-13,17-di（3-disulfidepropyl）porphyrin]bearing the symmetrical disulphide bond and its metal complexes have been successfully prepared by means of modification on naturally easily derived heme.The results are described by MS-MS and UV-vis spectroscopy.展开更多
The study describes chemo-enzymatic synthesis of organic disulphide compounds. The reaction was initiated by hydrolysis of thiol acetates using hydrolytic enzyme lipase (PPL) immobilized on to magnetic nanoparticles a...The study describes chemo-enzymatic synthesis of organic disulphide compounds. The reaction was initiated by hydrolysis of thiol acetates using hydrolytic enzyme lipase (PPL) immobilized on to magnetic nanoparticles and subsequent formation of organic disulphide compounds. Lipase was immobilized on to the magnetic nanoparticles by co-precipitation method via epichlorohydrin chitosan cross-linking, under mild and eco-friendly conditions. The immobilized lipase enzyme exhibited broad range of substrate specificity in synthesizing disulphide compounds, which involves both intra and inter-molecular disulphide bond formation under anaerobic conditions. The disulphide compounds synthesized also show a promising antimicrobial activity.展开更多
Objectives. Cancer is a very widespread disorder known in world wide since long, but its biochemical features remain unclear. Thyroid carcinomas are the most common endocrine cancer and its frequency continues to esca...Objectives. Cancer is a very widespread disorder known in world wide since long, but its biochemical features remain unclear. Thyroid carcinomas are the most common endocrine cancer and its frequency continues to escalate. There is evidence that the serum concentration of TSH is an unreliant predictor for the diagnosis of thyroid cancer. The formation of the plasma thiol pool from low and large molecular weight proteins suggests that thiol/disulfide balance is important in cancerous cases. The aim of this study was to investigate an oxidative stress marker (thiol/disulphide homeostasis) and IMA (Ischemia modified albumin), Albumin, CEA (Carcinoembryonic antigen), TSH (Thyroid stimulate hormone), thyroxine (T4), free thyroxine (FT4), triiodothyronine (T3) and free triiodothyronine (FT3) in patients with thyroid cancer and compare the results with healthy controls for the first time in literature. Materials-Methods: A total of 43 participants including 23 patients with thyroid cancer and 20 healthy individuals were included in the study. Serum levels of TSH, T4, FT4, T3 and FT3 have been measured during treatment and follow-up of patients with thyroid carcinoma. Serum levels of TSH, T4, FT4, T3 and FT3, IMA, Albumin, CEA, Native thiol (-SH), disulfide (-S-S) and total thiol (TT) as well as disulphide/native thiol and disulphide/total thiol ratios were compared between the groups. Native thiol, disulfide and total thiol concentrations were measured with a novel automated method (Roche, cobas 501, Mannheim, Germany). Results and conclusion: This paper discusses an oxidative stress marker (thiol/disulphide homeostasis) and tumor markers IMA, Albumin, CEA, TSH, T4, FT4, T3 and FT3 in patients with thyroid cancer and compare the results with healthy controls. Mean age at participant was 41.73 years for thyroid cancer patients (21 females/2 males). A control group of 20 participants was included the study (19 females/1 male, mean age 51.75).展开更多
Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two...Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two-dimensional material of group-IV transition metal dichalcogenides. For the first time, we demonstrate a simple and cost-effective method to grow layered belt-like nanocrystals of HfS2 with a notably large interlayer spacing followed by their chemical exfoliation. Various microscopic and spectroscopic techniques confirm that these as-grown crystals exfoliate into single or multiple layers in a few minutes using solvent assisted ultrasonification method in N-cyclohexyl-2- pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against surface degradation. Furthermore, we demonstrate that these nanosheets hold potential for electronic applications by fabricating a field-effect transistor based on few-layered HfS2, exhibiting a field-effect mobility of 0.95 cm2/（V.s） with a high on/off current modulation ratio of 10,000 in ambient conditions. The method is scalable and has a potential significance for both academic and industrial purposes.展开更多
Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because ofits severe adhesive wear tendency.The surface modifications through texturing and surface coa...Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because ofits severe adhesive wear tendency.The surface modifications through texturing and surface coating were used to enhance the surfaceproperties of the titanium alloy substrate.Hard and wear resistant coatings such as TiAlN and AlCrN were applied over texturedtitanium alloy surfaces with chromium as interlayer.To improve the friction and wear resisting performance of hard coatings further,solid lubricant,molybdenum disulphide(MoS2),was deposited on dimples made over hard coatings.Unidirectional sliding weartests were performed with pin on disc contact geometry,to evaluate the tribological performance of coated substrates.The tests wereperformed under three different normal loads for a period of40min at sliding velocity of2m/s.The tribological behaviours ofmulti-layer coatings such as coating structure,friction coefficient and specific wear rate were investigated and analyzed.The lowerfriction coefficient of approximately0.1was found at the early sliding stage,which reduces the material transfer and increases thewear life.Although,the friction coefficient increased to high values after MoS2coating was partially removed,substrate was stillprotected against wear by underlying hard composite layer.展开更多
Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter t...Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.展开更多
The isolation of the first two-dimensional material, graphene-a monolayer of carbon atoms arranged in a hexagonal lattice-opened new exciting opportunities in the field of condensed matter physics and materials. Its i...The isolation of the first two-dimensional material, graphene-a monolayer of carbon atoms arranged in a hexagonal lattice-opened new exciting opportunities in the field of condensed matter physics and materials. Its isolation and subsequent studies demonstrated that it was possible to obtain sheets of atomically thin crystals and that these were stable, and they also began to show its outstanding properties, thus opening the door to a whole new family of materials, known as two-dimensional materials or 2D materials. The great interest in different 2D materials is motivated by the variety of properties they show, being candidates for numerous applications.Additionally, the combination of 2D crystals allows the assembly of composite, on-demand materials, known as van der Waals heterostructures, which take advantage of the properties of those materials to create functionalities that otherwise would not be accessible. For example, the combination of 2D materials, which can be done with high precision, is opening up opportunities for the study of new challenges in fundamental physics and novel applications. Here we review the latest fundamental discoveries in the area of 2D materials and offer a perspective on the future of the field.展开更多
Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evoluti...Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction(HER)occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed.Therefore,efficient platinum group metals(PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded.In this scenario,molybdenum disulfide(MoS_(2))owing to efficacious structural attributes and optimum hydrogen-binding free energy(ΔG_(H*))is emerging as a reliable alternative to PGMs.However,the performance of MoS_(2)-based electrocatalysts is still far away from the benchmark performance.The HER activity of MoS_(2)can be improved by engineering the structural parameters i.e.,doping,defects inducement,modulating the electronic structure,stabilizing the 1 T phase,creating nanocomposites,and altering the morphologies using appropriate fabrication pathways.Here,we have comprehensively reviewed the majority of the scientific endeavors published in recent years to uplift the HER activity of MoS_(2)-based electrocatalysts using different methods.Advancements in the major fabrication strategies including hydrothermal synthesis methods,chemical vapor deposition,exfoliation techniques,plasma treatments,chemical methodologies,etc.to tune the structural parameters and hence their ultimate influence on the electrocatalytic activity in acidic and/or alkaline media have been thoroughly discussed.This study can provide encyclopedic insights about the fabrication routes that have been pursued to improve the HER performance of MoS_(2)-based electrocatalysts.展开更多
A microwave-assisted solid phase synthesis for endothelin 1 is presented.Reduced endothelin 1 was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.The who...A microwave-assisted solid phase synthesis for endothelin 1 is presented.Reduced endothelin 1 was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.The whole peptide was cleaved from the resin and two disulphide bridges were formed under air oxidation at room temperature.The purity and efficiency of synthesizing the peptide is much higher than other methods used before.展开更多
Human urotension-Ⅱ was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy. Disulphide bridge was formed on solid phase with the irradiation of microwave, t...Human urotension-Ⅱ was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy. Disulphide bridge was formed on solid phase with the irradiation of microwave, then the whole peptide was cleaved from the resin. The purity of crude peptide cyclized under microwave irradiation was higher than that under room temperature.展开更多
During liquefaction of the ejaculate, the semen coagulum proteins semenogelin I （SEMG1） and semenogelin Ⅱ （SEMG2） are degraded to low molecular mass fragments by kallikrein-related peptidase 3 （KLK3）, also know...During liquefaction of the ejaculate, the semen coagulum proteins semenogelin I （SEMG1） and semenogelin Ⅱ （SEMG2） are degraded to low molecular mass fragments by kallikrein-related peptidase 3 （KLK3）, also known as prostate-specific antigen. Semenogelin molecules initiate their own destruction by chelating Zn^2＋ that normally would completely inhibit the proteolytic activity of KLK3. In a similar way, semenogelins might regulate the activity of kallikrein-related peptidases in the epididymis, something that might be of importance for the maturation of spermatozoa or generation of anti-bacterial peptides. Studies on the evolution of semen coagulum proteins have revealed that most of them carry an exon that displays a rapid and unusual evolution. As a consequence, homologous proteins in rodents and primates show almost no conservation in primary structure. Further studies on their evolution suggest that the progenitor of the semen coagulum proteins probably was a protease inhibitor that might have displayed antimicrobial activity. The semenogelin locus on chromosome 20 contains at least 17 homologous genes encoding probable protease inhibitors with homology to semen coagulum proteins. All of these are highly expressed in the epididymis where they, similar to the semenogelins, could affect the maturation of spermatozoa or display antibacterial properties. （Asian J Androl 2007 July; 9： 540-544）展开更多
γ-Gliadins are an important component of wheat seed storage proteins. Four novel γ-gliadin genes （Gli-ngl to Gli-ng4） were cloned from wheat （Triticum aestivum） and Aegilops species. The novel γ-gliadins were m...γ-Gliadins are an important component of wheat seed storage proteins. Four novel γ-gliadin genes （Gli-ngl to Gli-ng4） were cloned from wheat （Triticum aestivum） and Aegilops species. The novel γ-gliadins were much smaller in molecular size when compared to the typical γ-gliadins, which was caused by deletion of the non-repetitive domain, glutamine-rich region, 3＂ part of the repetitive domain, and 5＇ part of the C-terminal, possibly due to illegitimate recombination between the repetitive domain and the C-terminal. As a result, Gli-ngl and Gli-ng4 only contained two and three cysteine residues, respectively. Gli-ngl, as the representative of novel γ-gliadin genes, has been sub-cloned into an Escherichia coli expression system. SDS- PAGE indicated that the both cysteine residues of Gli-ngl could participate in the formation of intermolecular disulphide bonds in vitro. Successful cloning of Gli-ngl from seed cDNA of T. aestivum cv. Chinese Spring suggested that these novel γ-gliadin genes were normally transcribed during the development of seeds. Phylogenic analysis indicated that the four novel γ-gliadin genes had a closer relationship with those from the B （S） genome of wheat.展开更多
This article intends to illustrate the Darcy flow and melting heat transmission in micropolar liquid.The major advantage of micropolar fluid is the liquid particle rotation through an independent kinematic vector name...This article intends to illustrate the Darcy flow and melting heat transmission in micropolar liquid.The major advantage of micropolar fluid is the liquid particle rotation through an independent kinematic vector named the microrotation vector.The novel aspects of the Cattaneo-Christov(C-C)heat flux and Joule heating are incorporated in the energy transport expression.Two different nanoparticles,namely,MoS2 and MgO,are suspended into the base-fluid.The governing partial differential equations(PDEs)of the prevailing problem are slackening into ordinary differential expressions(ODEs)via similarity transformations.The resulting mathematical phenomenon is illustrated by the implication of fourth-fifth order Runge-Kutta-Fehlberg(RKF)scheme.The fluid velocity and temperature distributions are deliberated by using graphical phenomena for multiple values of physical constraints.The results are displayed for both molybdenum disulphide and magnesium oxide nanoparticles.A comparative benchmark in the limiting approach is reported for the validation of the present technique.It is revealed that the incrementing material constraint results in a higher fluid velocity for both molybdenum disulphide and magnesium oxide nanoparticle situations.展开更多
Reaction of CuBr2 with TabHPF6/Et3N in methanol followed by dissolving the resulting precipitate in hydrobromic acid yielded purple blocks of the title complex [Tab-Tab][CuBr4] 1 （C18H26CuBraN2S2）. 1 crystallizes in...Reaction of CuBr2 with TabHPF6/Et3N in methanol followed by dissolving the resulting precipitate in hydrobromic acid yielded purple blocks of the title complex [Tab-Tab][CuBr4] 1 （C18H26CuBraN2S2）. 1 crystallizes in the monoclinic system, space group P2 1/n with a = 9.686（3）, b = 19.257（5）, c = 13.399（4） ,A, β= 93.610（9）°, V= 2494.2（13） ,A^3, Z= 4, Dc = 1.911 g/cm^3, T= 193（2） K, Mr = 717.71, F（000） = 1396,μ = 74.58 cm^-1, S = 1.126, R = 0.0748 and wR = 0.1736 for 2921 observed reflections with 1 〉 2σ（I）. The structure of 1 contains a discrete [CuBr4]^2- dianion and a [Tab-Tab]^2＋ dication. In the dianion, the Cu atom is coordinated to four Br atoms forming a distorted tetrahedral coordination geometry. The bromides of the dianion interact with the H atoms of the phenyl and methyl groups of the dications to form a 1D hydrogen-bonded chain.展开更多
The outstanding thermal,optical,electrical and mechanical properties of molybdenum disolphide(MoS_(2))heterostructures make them exceptional candidates for an extensive area of applications.Nevertheless,despite consid...The outstanding thermal,optical,electrical and mechanical properties of molybdenum disolphide(MoS_(2))heterostructures make them exceptional candidates for an extensive area of applications.Nevertheless,despite considerable technological and academic interest,there is presently a fewinformation regarding the mechanical properties of these novel two-dimensional(2D)materials in the presence of the defects.In thismanuscript,we performed extensive molecular dynamics simulations on pre-cracked and pre-notched all-molybdenum disolphide(MoS_(2))heterostructure systems using ReaxFF force field.Therefore,we study the influence of several central-crack lengths and notch diameters on the mechanical response of 2H phase,1T phase and composite 2H/1T MoS_(2) monolayers with different concentrations of 1T phase in 2H phase,under uniaxial tensile loading at room temperature.Our ReaxFF models reveal that larger cracks and notches decrease the strength of all 2D MoS_(2) single-layer heterostructures.Additionally,for all studied crack and notch sizes,2H phase of MoS_(2) films exhibits the largest strength.Maximum tensile stress of composite 2H/1T MoS_(2) nanosheet with different concentrations are higher than those for the equivalent 1T phase,which implies that the pre-cracked composite structure is remarkably stronger than the equivalent 1T phase.The comparison of the results for cracked and notched all-MoS_(2) nanosheet heterostructures reveal that the load bearing capacity of the notched samples of monolayerMoS_(2) are higher than the cracked ones.展开更多
MoSx (x = 1.79 ￣ 2.34) films of 200 nm thickness are deposited onto brass and C20 steel substrates by the ion beam assisted technique, respectively. Structures and compositions of these films, and changes in valence ...MoSx (x = 1.79 ￣ 2.34) films of 200 nm thickness are deposited onto brass and C20 steel substrates by the ion beam assisted technique, respectively. Structures and compositions of these films, and changes in valence states of the Mo element are examined by XRD and XPS before and after wear. The lubrication properties and wear resistances for two kinds of samples are evaluated using a pin-on-disk installation in atmosphere at the room temperature. Tribo-wear behaviours and the microstructures between two kinds of samples exhibit obvious differences.展开更多
Background:Cholangiocarcinoma(CCA)is a cancer type that builds in the bile ducts that carry digestive fluid,bile.These ducts connect the liver to the gallbladder and the small intestine.The disease is often diagnosed ...Background:Cholangiocarcinoma(CCA)is a cancer type that builds in the bile ducts that carry digestive fluid,bile.These ducts connect the liver to the gallbladder and the small intestine.The disease is often diagnosed at an advanced stage,resulting in a low 5-year survival rate.This study aims to evaluate the concentrations of serum thiol/disulfide in CCA patients and healthy volunteers and investigate the association between oxidative activity and clinical and pathological characteristics in CCA patients.By examining the relationship between reduced thiol/disulfide measures and tumorigenesis of the disease,we can potentially identify an unfavourable prognosis in CCA patients.Methods:To assess the status of thiol/disulfide in the blood of Cholangiocarcinoma patients using a novel automated homeostasis assay,we recruited 55 individuals for this study(CCA patients,n=27;healthy volunteers,n=28).We measured the levels of serum total thiol(TT)(–SH+–S-S–),native thiol(NT)(–SH),and disulfide(DD)(–S-S–)in both the CCA group and the control group.Additionally,we calculated the ratio of thiol/disulfide(–SH/–S-S–).Results:We explored the relationship between oxidative activity and clinical and pathological characteristics in CCA patients.The study found no significant differences in age and sex between CCA patients and controls.NT and TT levels were higher in the control group compared to the CCA group.However,the disulfide level did not significantly differ between the two groups.Pearson's correlation matrix analysis revealed positive correlations between TT and NT levels and negative correlations between NT/TT%,DD level,and DD/TT%.Conclusion:Our findings suggest a statistical difference in serum thiol/disulfide parameters.As a marker of total oxidant status,thiol and disulfide levels have decreased in patients with CCA.However,no correlation was found between the tumour markers CEA and CA19-9 and thiol levels.A decrease in blood thiol and disulfide concentrations or the ratio of thiol to disulfide may indicate an increase in oxidative stress and decreased antioxidant capacity.As an indication of the prognosis of cholangiocarcinoma disease in the early period,it may be used to determine the effectiveness of medical interventions.The NT/TT%,disulfide/native thiol percentage,and DD/TT%ratios did not significantly change between the groups.Therefore,measuring serum thiol levels could be a helpful marker for assessing prognosis in the early stages of CCA.Nevertheless,further studies must validate these results and investigate the underlying mechanisms.展开更多
基金Project supported by the National Scientific Research Project of China(Grant No.61177047)Beijing Municipal Natural Science Foundation+1 种基金China(Grant No.1102005)the Basic Research Foundation of Beijing University of Technology,China(Grant No.X3006111201501)
文摘We demonstrate a passively Q-switched Yb：LSO laser based on tungsten disulphide （WS2） saturable absorber op- erating at 1034 nm and 1056 nm simultaneously. The saturable absorbers were fabricated by spin coating method. With low speed, the WS2 nanoplatelets embedded in polyvinyl alcohol could be coated on a BK7 glass substrate coated with high-refractive-index thin polymer. The shortest pulse width of 1.6 gs with a repetition rate of 76.9 kHz is obtained. As the pump power increases to 9 W, the maximum output power is measured to be 250 mW, corresponding to a single pulse energy of 3.25 μJ. To the best of our knowledge, this is the first time to obtain dual-wavelength Q-switched solid-state laser using few-layer WS2 nanoplatelets.
基金supported by The Australian Research Council (Project ARC FL170100101)the Research Project Supported by Shanxi Scholarship Council of China (2021-128)Supported by the Fundamental Research Program of Shanxi Province (20210302124356).
文摘Lithium-ion batteries(LIBs)are excellent electrochemical energy sources,albeit with existing challenges,including high costs and safety concerns.Magnesium-ion batteries(MIBs)are one of the potential alternatives.However,the performance of MIBs is poor due to their sluggish solid-state Mg^(2+) diffusion kinetics and severe electrode polarizability.Rechargeable magnesium-ion/lithium-ion(Mg^(2+)/Li^(+))hybrid batteries(MLHBs)with Mg^(2+) and Li+as the charge carriers create a synergy between LIBs and MIBs with significantly improved charge transport kinetics and reliable safety features.However,MLHBs are yet to reach a reasonable electrochemical performance as expected.This work reports a composite electrode material with highly defective two-dimensional(2D)tin sulphide nanosheets(SnS_(x))encapsulated in three-dimensional(3D)holey graphene foams(HGF)(SnS_(x)/HGF),which exhibits a specific capacity as high as 600 mAh g^(−1) at 50 mA g^(−1) and a compelling specific energy density of~330 Wh kg^(−1).The excellent electrochemical performance surpasses previously reported hybrid battery systems based on intercalation-type cathode materials under comparable conditions.The role played by the defects in the SnS_(x)/HGF composite is studied to understand the origin of the observed excellent electrochemical performance.It is found that it is closely related to the defect structure in SnS_(x),which offers percolation pathways for efficient ion transport and increased internal surface area assessable to the charge carriers.The defective sites also absorb structural stress caused by Mg^(2+) and Li+insertion.This work is an important step towards realizing high-capacity cathode materials with fast charge transport kinetics for hybrid batteries.
基金supported by Jiangsu Natural Science Foundation(NoBK2009386)NUST research founding(No2010GJPY043)
文摘A novel disulphide derivatised deuteroporphyrin 2,7,12,18-tetramethyl-13,17-（propionylaminoethyldithioethyl amino-formy-lethyl） -29,34-bis-（methoxyformyl）porphyrin（PDTEP,3） and its cobalt（Ⅱ） complex（Co（II）PDTEP,4） were conveniently synthesized. The disulphide functional group of 4 allowed its stable immobilization on gold electrodes.The modified electrode was characterized by IR and confirmed electrochemically and showed good stability and catalytic activity toward the electro-catalyzed reduction of hydrogen peroxide.
基金support from Jiangsu Natural Science Foundation(No.BK2009386)Science and Technology Development Foundation of Nanjing University of Science and Technology(No.XKF 09008 and No.2010GJPY043)
文摘A novel thiol-derivative porphyrin[2,7,12,18-tetramethyl-13,17-di（3-disulfidepropyl）porphyrin]bearing the symmetrical disulphide bond and its metal complexes have been successfully prepared by means of modification on naturally easily derived heme.The results are described by MS-MS and UV-vis spectroscopy.
文摘The study describes chemo-enzymatic synthesis of organic disulphide compounds. The reaction was initiated by hydrolysis of thiol acetates using hydrolytic enzyme lipase (PPL) immobilized on to magnetic nanoparticles and subsequent formation of organic disulphide compounds. Lipase was immobilized on to the magnetic nanoparticles by co-precipitation method via epichlorohydrin chitosan cross-linking, under mild and eco-friendly conditions. The immobilized lipase enzyme exhibited broad range of substrate specificity in synthesizing disulphide compounds, which involves both intra and inter-molecular disulphide bond formation under anaerobic conditions. The disulphide compounds synthesized also show a promising antimicrobial activity.
文摘Objectives. Cancer is a very widespread disorder known in world wide since long, but its biochemical features remain unclear. Thyroid carcinomas are the most common endocrine cancer and its frequency continues to escalate. There is evidence that the serum concentration of TSH is an unreliant predictor for the diagnosis of thyroid cancer. The formation of the plasma thiol pool from low and large molecular weight proteins suggests that thiol/disulfide balance is important in cancerous cases. The aim of this study was to investigate an oxidative stress marker (thiol/disulphide homeostasis) and IMA (Ischemia modified albumin), Albumin, CEA (Carcinoembryonic antigen), TSH (Thyroid stimulate hormone), thyroxine (T4), free thyroxine (FT4), triiodothyronine (T3) and free triiodothyronine (FT3) in patients with thyroid cancer and compare the results with healthy controls for the first time in literature. Materials-Methods: A total of 43 participants including 23 patients with thyroid cancer and 20 healthy individuals were included in the study. Serum levels of TSH, T4, FT4, T3 and FT3 have been measured during treatment and follow-up of patients with thyroid carcinoma. Serum levels of TSH, T4, FT4, T3 and FT3, IMA, Albumin, CEA, Native thiol (-SH), disulfide (-S-S) and total thiol (TT) as well as disulphide/native thiol and disulphide/total thiol ratios were compared between the groups. Native thiol, disulfide and total thiol concentrations were measured with a novel automated method (Roche, cobas 501, Mannheim, Germany). Results and conclusion: This paper discusses an oxidative stress marker (thiol/disulphide homeostasis) and tumor markers IMA, Albumin, CEA, TSH, T4, FT4, T3 and FT3 in patients with thyroid cancer and compare the results with healthy controls. Mean age at participant was 41.73 years for thyroid cancer patients (21 females/2 males). A control group of 20 participants was included the study (19 females/1 male, mean age 51.75).
文摘Producing environmentally stable monolayers and few-layers of hafnium disulphide （HfS2） with a high yield to reveal its unlocked electronic and optoelectronic applications is still a challenge. HfS2 is a layered two-dimensional material of group-IV transition metal dichalcogenides. For the first time, we demonstrate a simple and cost-effective method to grow layered belt-like nanocrystals of HfS2 with a notably large interlayer spacing followed by their chemical exfoliation. Various microscopic and spectroscopic techniques confirm that these as-grown crystals exfoliate into single or multiple layers in a few minutes using solvent assisted ultrasonification method in N-cyclohexyl-2- pyrrolidone. The exfoliated nanosheets of HfS2 exhibit an indirect bandgap of 1.3 eV with high stability against surface degradation. Furthermore, we demonstrate that these nanosheets hold potential for electronic applications by fabricating a field-effect transistor based on few-layered HfS2, exhibiting a field-effect mobility of 0.95 cm2/（V.s） with a high on/off current modulation ratio of 10,000 in ambient conditions. The method is scalable and has a potential significance for both academic and industrial purposes.
文摘Titanium alloys are poor in wear resistance and it is not suitable under sliding conditions even with lubrication because ofits severe adhesive wear tendency.The surface modifications through texturing and surface coating were used to enhance the surfaceproperties of the titanium alloy substrate.Hard and wear resistant coatings such as TiAlN and AlCrN were applied over texturedtitanium alloy surfaces with chromium as interlayer.To improve the friction and wear resisting performance of hard coatings further,solid lubricant,molybdenum disulphide(MoS2),was deposited on dimples made over hard coatings.Unidirectional sliding weartests were performed with pin on disc contact geometry,to evaluate the tribological performance of coated substrates.The tests wereperformed under three different normal loads for a period of40min at sliding velocity of2m/s.The tribological behaviours ofmulti-layer coatings such as coating structure,friction coefficient and specific wear rate were investigated and analyzed.The lowerfriction coefficient of approximately0.1was found at the early sliding stage,which reduces the material transfer and increases thewear life.Although,the friction coefficient increased to high values after MoS2coating was partially removed,substrate was stillprotected against wear by underlying hard composite layer.
基金Financial assistance from Armament Research Board, New Delhi, India
文摘Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys,7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant Mo S2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.
基金financial support through the project Medium-Sized Centre programme R-723-000-001-281support from EU Flagship Programs (Graphene CNECTICT-604391 and 2D-SIPC Quantum Technology)European Research Council Synergy Grant Hetero2D, the Royal Society, EPSRC grants EP/N010345/1, EP/ P026850/1, EP/S030719/1.
文摘The isolation of the first two-dimensional material, graphene-a monolayer of carbon atoms arranged in a hexagonal lattice-opened new exciting opportunities in the field of condensed matter physics and materials. Its isolation and subsequent studies demonstrated that it was possible to obtain sheets of atomically thin crystals and that these were stable, and they also began to show its outstanding properties, thus opening the door to a whole new family of materials, known as two-dimensional materials or 2D materials. The great interest in different 2D materials is motivated by the variety of properties they show, being candidates for numerous applications.Additionally, the combination of 2D crystals allows the assembly of composite, on-demand materials, known as van der Waals heterostructures, which take advantage of the properties of those materials to create functionalities that otherwise would not be accessible. For example, the combination of 2D materials, which can be done with high precision, is opening up opportunities for the study of new challenges in fundamental physics and novel applications. Here we review the latest fundamental discoveries in the area of 2D materials and offer a perspective on the future of the field.
基金the Italian Ministry of University and Research(MUR)through the“Rita Levi Montalcini 2018”Fellowship(Grant number PGR18MAZLI)ENEA–UNIMIB PNRR agreement(Attività1.1.3 del PNRR POR H2)+1 种基金the Ministry of Science and Technology(State of Israel)and the Ministry of Foreign Affairs and International Cooperation–Directorate General for Cultural and Economic Promotion and Innovation(Italian Republic),respectively,within the bilateral project Italy-Israel(WE-CAT)the Italian ministry MUR for funding through the FISR 2019 project AMPERE(FISR2019_01294)。
文摘Hydrogen production via water electrolysis defines the novel energy vector for achieving a sustainable society.However,the true progress of the given technology is hindered by the sluggish and complex hydrogen evolution reaction(HER)occurring at the cathodic side of the system where overpriced and scarce Pt-based electrocatalysts are usually employed.Therefore,efficient platinum group metals(PGMs)-free electrocatalysts to carry out HER with accelerated kinetics are urgently demanded.In this scenario,molybdenum disulfide(MoS_(2))owing to efficacious structural attributes and optimum hydrogen-binding free energy(ΔG_(H*))is emerging as a reliable alternative to PGMs.However,the performance of MoS_(2)-based electrocatalysts is still far away from the benchmark performance.The HER activity of MoS_(2)can be improved by engineering the structural parameters i.e.,doping,defects inducement,modulating the electronic structure,stabilizing the 1 T phase,creating nanocomposites,and altering the morphologies using appropriate fabrication pathways.Here,we have comprehensively reviewed the majority of the scientific endeavors published in recent years to uplift the HER activity of MoS_(2)-based electrocatalysts using different methods.Advancements in the major fabrication strategies including hydrothermal synthesis methods,chemical vapor deposition,exfoliation techniques,plasma treatments,chemical methodologies,etc.to tune the structural parameters and hence their ultimate influence on the electrocatalytic activity in acidic and/or alkaline media have been thoroughly discussed.This study can provide encyclopedic insights about the fabrication routes that have been pursued to improve the HER performance of MoS_(2)-based electrocatalysts.
基金supported by the key project of Chinese Ministry of Education(No.109086)
文摘A microwave-assisted solid phase synthesis for endothelin 1 is presented.Reduced endothelin 1 was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.The whole peptide was cleaved from the resin and two disulphide bridges were formed under air oxidation at room temperature.The purity and efficiency of synthesizing the peptide is much higher than other methods used before.
文摘Human urotension-Ⅱ was synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy. Disulphide bridge was formed on solid phase with the irradiation of microwave, then the whole peptide was cleaved from the resin. The purity of crude peptide cyclized under microwave irradiation was higher than that under room temperature.
文摘During liquefaction of the ejaculate, the semen coagulum proteins semenogelin I （SEMG1） and semenogelin Ⅱ （SEMG2） are degraded to low molecular mass fragments by kallikrein-related peptidase 3 （KLK3）, also known as prostate-specific antigen. Semenogelin molecules initiate their own destruction by chelating Zn^2＋ that normally would completely inhibit the proteolytic activity of KLK3. In a similar way, semenogelins might regulate the activity of kallikrein-related peptidases in the epididymis, something that might be of importance for the maturation of spermatozoa or generation of anti-bacterial peptides. Studies on the evolution of semen coagulum proteins have revealed that most of them carry an exon that displays a rapid and unusual evolution. As a consequence, homologous proteins in rodents and primates show almost no conservation in primary structure. Further studies on their evolution suggest that the progenitor of the semen coagulum proteins probably was a protease inhibitor that might have displayed antimicrobial activity. The semenogelin locus on chromosome 20 contains at least 17 homologous genes encoding probable protease inhibitors with homology to semen coagulum proteins. All of these are highly expressed in the epididymis where they, similar to the semenogelins, could affect the maturation of spermatozoa or display antibacterial properties. （Asian J Androl 2007 July; 9： 540-544）
基金finically supported by the National Natural Science Foundation of China (31230053)
文摘γ-Gliadins are an important component of wheat seed storage proteins. Four novel γ-gliadin genes （Gli-ngl to Gli-ng4） were cloned from wheat （Triticum aestivum） and Aegilops species. The novel γ-gliadins were much smaller in molecular size when compared to the typical γ-gliadins, which was caused by deletion of the non-repetitive domain, glutamine-rich region, 3＂ part of the repetitive domain, and 5＇ part of the C-terminal, possibly due to illegitimate recombination between the repetitive domain and the C-terminal. As a result, Gli-ngl and Gli-ng4 only contained two and three cysteine residues, respectively. Gli-ngl, as the representative of novel γ-gliadin genes, has been sub-cloned into an Escherichia coli expression system. SDS- PAGE indicated that the both cysteine residues of Gli-ngl could participate in the formation of intermolecular disulphide bonds in vitro. Successful cloning of Gli-ngl from seed cDNA of T. aestivum cv. Chinese Spring suggested that these novel γ-gliadin genes were normally transcribed during the development of seeds. Phylogenic analysis indicated that the four novel γ-gliadin genes had a closer relationship with those from the B （S） genome of wheat.
文摘This article intends to illustrate the Darcy flow and melting heat transmission in micropolar liquid.The major advantage of micropolar fluid is the liquid particle rotation through an independent kinematic vector named the microrotation vector.The novel aspects of the Cattaneo-Christov(C-C)heat flux and Joule heating are incorporated in the energy transport expression.Two different nanoparticles,namely,MoS2 and MgO,are suspended into the base-fluid.The governing partial differential equations(PDEs)of the prevailing problem are slackening into ordinary differential expressions(ODEs)via similarity transformations.The resulting mathematical phenomenon is illustrated by the implication of fourth-fifth order Runge-Kutta-Fehlberg(RKF)scheme.The fluid velocity and temperature distributions are deliberated by using graphical phenomena for multiple values of physical constraints.The results are displayed for both molybdenum disulphide and magnesium oxide nanoparticles.A comparative benchmark in the limiting approach is reported for the validation of the present technique.It is revealed that the incrementing material constraint results in a higher fluid velocity for both molybdenum disulphide and magnesium oxide nanoparticle situations.
基金The project was supported by the National Natural Science Foundation of China (No. 20525101), the NSF of Jiangsu Province (No. BK2004205), State Key Laboratory of Structural Chemistry (No. 030066) and Key Laboratory of Organic Synthesis of Jiangsu Province (No. JSK001)
文摘Reaction of CuBr2 with TabHPF6/Et3N in methanol followed by dissolving the resulting precipitate in hydrobromic acid yielded purple blocks of the title complex [Tab-Tab][CuBr4] 1 （C18H26CuBraN2S2）. 1 crystallizes in the monoclinic system, space group P2 1/n with a = 9.686（3）, b = 19.257（5）, c = 13.399（4） ,A, β= 93.610（9）°, V= 2494.2（13） ,A^3, Z= 4, Dc = 1.911 g/cm^3, T= 193（2） K, Mr = 717.71, F（000） = 1396,μ = 74.58 cm^-1, S = 1.126, R = 0.0748 and wR = 0.1736 for 2921 observed reflections with 1 〉 2σ（I）. The structure of 1 contains a discrete [CuBr4]^2- dianion and a [Tab-Tab]^2＋ dication. In the dianion, the Cu atom is coordinated to four Br atoms forming a distorted tetrahedral coordination geometry. The bromides of the dianion interact with the H atoms of the phenyl and methyl groups of the dications to form a 1D hydrogen-bonded chain.
基金The authors extend their appreciation to the Distinguished Scientist Fellowship Program(DSFP)at King Saud University for funding this work.
文摘The outstanding thermal,optical,electrical and mechanical properties of molybdenum disolphide(MoS_(2))heterostructures make them exceptional candidates for an extensive area of applications.Nevertheless,despite considerable technological and academic interest,there is presently a fewinformation regarding the mechanical properties of these novel two-dimensional(2D)materials in the presence of the defects.In thismanuscript,we performed extensive molecular dynamics simulations on pre-cracked and pre-notched all-molybdenum disolphide(MoS_(2))heterostructure systems using ReaxFF force field.Therefore,we study the influence of several central-crack lengths and notch diameters on the mechanical response of 2H phase,1T phase and composite 2H/1T MoS_(2) monolayers with different concentrations of 1T phase in 2H phase,under uniaxial tensile loading at room temperature.Our ReaxFF models reveal that larger cracks and notches decrease the strength of all 2D MoS_(2) single-layer heterostructures.Additionally,for all studied crack and notch sizes,2H phase of MoS_(2) films exhibits the largest strength.Maximum tensile stress of composite 2H/1T MoS_(2) nanosheet with different concentrations are higher than those for the equivalent 1T phase,which implies that the pre-cracked composite structure is remarkably stronger than the equivalent 1T phase.The comparison of the results for cracked and notched all-MoS_(2) nanosheet heterostructures reveal that the load bearing capacity of the notched samples of monolayerMoS_(2) are higher than the cracked ones.
文摘MoSx (x = 1.79 ￣ 2.34) films of 200 nm thickness are deposited onto brass and C20 steel substrates by the ion beam assisted technique, respectively. Structures and compositions of these films, and changes in valence states of the Mo element are examined by XRD and XPS before and after wear. The lubrication properties and wear resistances for two kinds of samples are evaluated using a pin-on-disk installation in atmosphere at the room temperature. Tribo-wear behaviours and the microstructures between two kinds of samples exhibit obvious differences.
文摘Background:Cholangiocarcinoma(CCA)is a cancer type that builds in the bile ducts that carry digestive fluid,bile.These ducts connect the liver to the gallbladder and the small intestine.The disease is often diagnosed at an advanced stage,resulting in a low 5-year survival rate.This study aims to evaluate the concentrations of serum thiol/disulfide in CCA patients and healthy volunteers and investigate the association between oxidative activity and clinical and pathological characteristics in CCA patients.By examining the relationship between reduced thiol/disulfide measures and tumorigenesis of the disease,we can potentially identify an unfavourable prognosis in CCA patients.Methods:To assess the status of thiol/disulfide in the blood of Cholangiocarcinoma patients using a novel automated homeostasis assay,we recruited 55 individuals for this study(CCA patients,n=27;healthy volunteers,n=28).We measured the levels of serum total thiol(TT)(–SH+–S-S–),native thiol(NT)(–SH),and disulfide(DD)(–S-S–)in both the CCA group and the control group.Additionally,we calculated the ratio of thiol/disulfide(–SH/–S-S–).Results:We explored the relationship between oxidative activity and clinical and pathological characteristics in CCA patients.The study found no significant differences in age and sex between CCA patients and controls.NT and TT levels were higher in the control group compared to the CCA group.However,the disulfide level did not significantly differ between the two groups.Pearson's correlation matrix analysis revealed positive correlations between TT and NT levels and negative correlations between NT/TT%,DD level,and DD/TT%.Conclusion:Our findings suggest a statistical difference in serum thiol/disulfide parameters.As a marker of total oxidant status,thiol and disulfide levels have decreased in patients with CCA.However,no correlation was found between the tumour markers CEA and CA19-9 and thiol levels.A decrease in blood thiol and disulfide concentrations or the ratio of thiol to disulfide may indicate an increase in oxidative stress and decreased antioxidant capacity.As an indication of the prognosis of cholangiocarcinoma disease in the early period,it may be used to determine the effectiveness of medical interventions.The NT/TT%,disulfide/native thiol percentage,and DD/TT%ratios did not significantly change between the groups.Therefore,measuring serum thiol levels could be a helpful marker for assessing prognosis in the early stages of CCA.Nevertheless,further studies must validate these results and investigate the underlying mechanisms.
