The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has be...The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has been found to be quite significant,indicating poor corrosion resistance in acetic acid.The maximum corrosion rate has been observed in 25% acetic acid solution at all three experimental temperatures.The decrease in corrosion rate after attaining a maximum value has been attributed to the deposition of corrosion product on the surface.Anodic polarization curves exhibit active behaviour at each concentration and temperature with a shift towards higher current density region and increased corrosion rates at higher temperatures.The cathodic polarization curves are almost identical irrespective either of the concentration of acetic acid or temperature.The results obtained by both the techniques are in good agreement,while the surface studies support the conclusions drawn from the weight loss method.展开更多
Calix resorcinarenes bearing four hydrophobic side chains ( Ar-Rn, Ar-Ph, and Ar-N) orient stably on water oil interface and show high solubilization capacities for organic compounds, such as long chain alcohols...Calix resorcinarenes bearing four hydrophobic side chains ( Ar-Rn, Ar-Ph, and Ar-N) orient stably on water oil interface and show high solubilization capacities for organic compounds, such as long chain alcohols, benzene, toluene and dyes. The capacities are high even near the cmc of polyalkylated calix resorcinarenes, but the solubilities of organic compounds(solubilizates) decrease with the increase of the size of the solubilizates. Ar-R 6, with a chain length of six carbons, is the most effective among Ar-R n , Ar-Ph, and Ar-N; 11 fold mol of hexanol is dissolved in 2×10 -3 mol/L Ar-R 6. Moreover, Ar-R n bearing four alkyl side chains solubilizes the chain alcohols of the same chain length mostly. The solubilization capacities are presumably brought by inclusion in a large cavity of the polyalkylated calix resorcinarenes and by an efficient orientation of the solubilizates.展开更多
In this study, the oxidative damage of α-terthienyl （α-T） to the Spodoptera litura （SL） cell and its mechanism were investigated. MTT was used to compare the toxicity of α-T and rotenone to the SL cell. The out...In this study, the oxidative damage of α-terthienyl （α-T） to the Spodoptera litura （SL） cell and its mechanism were investigated. MTT was used to compare the toxicity of α-T and rotenone to the SL cell. The output of malondialdehyde and relative content of glutathione were determined with 2-thiobarbituric acid （TBA） and 5, 5＇-dithio-bis （2-nitrobenzoic acid） （DTNB）, respectively. Transmission electron microscope （TEM） was employed to observe the influence of α-T on the membrane and organelle of the SL cell. The result showed that the IC50 value of α-T to the SL cell was 0.21 μg mL^-1, whereas the corresponding dose of rotenone was 12.25 μg mL^-1. The output of MDA had the same changing tendency with the concentration of α-T, whereas the content of GSH had the negative correlation with it. According to TEM, the cell membrane and karyotheca swelled and couldn＇t retain integrity, the intracellular substances leaked out, unidentified granules appeared in the SL cell. The mitochondria expanded, and the membrane and subcellular organelle were damaged severely. In this study, it was found that after oxidative damage induced by α-T, the output of MDA increased notably, whereas the relative content of GSH decreased. This indicated that the antioxidant ability of cell weakened. The result of TEM implied that the SL cell suffered from oxidative damage under the appointed dose.展开更多
The title compound,（E）-ethyl 2-（5-（3-methyl-2-butenyloxy）-2-（3-（4-（3-methyl-2-butenyloxy）phenyl） acryloyl） phenoxy）acetate（1）,has been synthesized and characterized by FT-IR and 1H-NMR spectroscopy,ESI-M...The title compound,（E）-ethyl 2-（5-（3-methyl-2-butenyloxy）-2-（3-（4-（3-methyl-2-butenyloxy）phenyl） acryloyl） phenoxy）acetate（1）,has been synthesized and characterized by FT-IR and 1H-NMR spectroscopy,ESI-MS,and X-ray single-crystal diffraction.FT-IR,1H-NMR and ESI-MS confirm the functional groups,particularly the ethyl groups in the ester moiety,of the compound.The single-crystal X-ray diffraction has revealed a monoclinic structure,space group P21/n with a = 14.6832（14）,b = 7.7581（7）,c = 23.075（2）,β = 101.670（2）o,V = 2574.2（4） ？3,Z = 4,Dc = 1.235 g/cm,μ = 0.085 mm-1,and F（000） = 1024.The skeleton of chalcone in the molecular structure is coplanar.展开更多
Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate capacitors.In the present investigation biopolyo...Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate capacitors.In the present investigation biopolyol was synthesized from Latvia-grown rapeseeds’oil by the transesterification method with triethanolamine,in an environmentally friendly process,without emission of harmful substances,at temperatures 175℃±5℃.Rigid,closed-cell rapeseed oil polyol polyurethane biofoams and petrochemical foams were made ensuring content of the renewable rapeseed oil polyol in ready foams 27 wt.%–29 wt.%.Dielectric permittivity of the polyurethane foams and the underlying monolithic petrochemical-origin polyurethane and biopolyurethane was measured with a non-destructive dielectric spectrometer equipped with a capacitive sensor of one-side access type at 16 discrete frequencies distributed geometrically over the band 10 Hz,…,330 kHz.Permittivity value of the gaseous phase in the closed-cells was estimated to beεg≈1.001 that corresponds to the values,characteristic for the most of gases.Dielectric permittivity of petrochemical polyurethane foams and the mentioned biofoams was compared with permittivity of polyurethane foams from industrial producers Sika JSC and General Plastics Manufacturing Co.Polyurethane foams of the developed formulation exhibit competitive,low dielectric permittivity,not exceeding that of the foams from industrial producers:petrochemical foams up to 550 kg/m^(3) and the mentioned biofoams,comprising the renewable rapeseed oil polyol,up to densities 230–250 kg/m^(3).Considering petrochemical-origin polyurethane foams as a heterogeneous media“Polymer—gaseous phase”,the applicability of the rule of mixture and Maxwell–Garnett equation to model mathematically the dependence of effective dielectric permittivity on the volume fraction of phases was showed.展开更多
BaTiO3∶Mn0.006Smx(x=0.001, 0.002, 0.003, 0.004, 0.006 respectively) ceramics were prepared by using sol-gel method and their resistivities at different temperatures were measured. The results showed that Mn element m...BaTiO3∶Mn0.006Smx(x=0.001, 0.002, 0.003, 0.004, 0.006 respectively) ceramics were prepared by using sol-gel method and their resistivities at different temperatures were measured. The results showed that Mn element may enhance the PTC characteristics of BaTiO3 ceramics. But the doped Mn element deteriorated the room temperature resistivities of the modified BaTiO3 ceramics which were greater than 105 Ω·m. Then, rare earth element Sm was penetrated into BaTiO3∶Mn0.06Smx ceramics in gaseous state, which largely decreased the room temperature resistivity to 3.20 Ω·m, and appeared as a NTC effect instead of PTC effect. The forming mechanism of NTC effect was explored through analyses of SEM and electric properties of Sm-penetrated BaTiO3∶Mn0.006Smx ceramics.展开更多
The correlation between shape and size of linear chains on the simple cubic lattice is investigated using a dynamicMonte Carlo technique. A positive correlation between the asphericity parameter A and the square of th...The correlation between shape and size of linear chains on the simple cubic lattice is investigated using a dynamicMonte Carlo technique. A positive correlation between the asphericity parameter A and the square of the end-to-end distanceR^2, as well as that between A and the square of the radius of gyration S^2, is found for both RW and SAW chains, indicatingthat a chain conformation of small size is usually more spherical than one of large size. The result can explain why the shapeof the SAW chain deviate much more from a sphere than that of the RW chain, and can also explain the similar dependenceof size and shape on chain stiffness and on the distance of the first bead of a chain from an infinitely large flat surface.展开更多
A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colo...A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.展开更多
A wavelength-dependent three-dimensional(3D)superlocalization imaging method on gold nanoislands(GNIs)chip was developed as a supersensitive single-molecule thyroid-stimulating hormone(TSH)nanobiosensor.Scattered and ...A wavelength-dependent three-dimensional(3D)superlocalization imaging method on gold nanoislands(GNIs)chip was developed as a supersensitive single-molecule thyroid-stimulating hormone(TSH)nanobiosensor.Scattered and fluorescent signals from gold nanoislands on the substrate and quantum dots(QDs)nanoprobes were simultaneously isolated and acquired within an evanescent field layer generated by total internal reflection(TIR)of incident light using a dual-view device.The 3D TIR fluorescence images of TSH-bound QDs on the GNIs were obtained using z-axis optical sectioning at 10nm intervals before/after immunoreaction to identify the optimal conditions for detection.The localized centroid position of QD nanoprobes and GNI were distinguished at a subdiffraction limit resolution using 3D Gaussian fitting to the point spread function.The QD TSH nanobiosensor using wavelength-dependent 3D TIR fluorescence-based single-molecule localization microscopy(3D TIRF-SLM)imaging technique showed an excellent detection limit of 90 yoctomoles(~54 molecules)and a wide linear dynamic range of 1.14 zmol/L-100 pmol/L for TSH.The detection sensitivity was about 4.4×10^(9)times higher than conventional enzyme-linked immunosorbent assay and could successfully quantify TSH in human serum.The wavelength-dependent 3D TIRF-SLM technique may emerge as a reliable platform for ultrahigh-sensitive nanobiosensors at the single-molecule level and early diagnosis with quantification of disease-related ultra-tracebiomolecules.展开更多
This article deals with the study of the viscoelastic and thermal properties of polyurethane (PU) rigid foamsfrom biobased and recycled components. Rapeseed oil (RO) and recycled poly(ethylene terephthalate)(PET) were...This article deals with the study of the viscoelastic and thermal properties of polyurethane (PU) rigid foamsfrom biobased and recycled components. Rapeseed oil (RO) and recycled poly(ethylene terephthalate)(PET) were used to synthesize PU polyols. Addition of adipic acid (ADA) to polyol resulted in improvedthermal and viscoelastic properties of foam materials. ADA content was varied from 1 to 6 wt%. Results ofthe dynamic mechanical spectra indicate an increase of the storage modulus E′ and the loss modulus E″ inthe whole temperature range for specimens with higher loading of ADA. In addition, damping factor shiftedto higher temperatures, but damping intensity remained almost unaffected by the compositions. Scanningelectron microscopy of the foams’ cross sections testified that the average cells’ size of 110 mm was unaffectedby the ADA content in polyol.展开更多
The widespread precatalyst (prepared in-situ or ex-situ) (arene) RuTsDPEN advocated for highly effectual asymmetric transfer hydrogenation (ATH) reactions with 2-propanol as hydrogen donor at ambient conditions, is pr...The widespread precatalyst (prepared in-situ or ex-situ) (arene) RuTsDPEN advocated for highly effectual asymmetric transfer hydrogenation (ATH) reactions with 2-propanol as hydrogen donor at ambient conditions, is proven to be unstable under the strong reducing conditions prevailing in the reaction mixtures (blend of alcohol and a base such as KOH). We assert that the true catalysts are the ruthenium metal nanoclusters formed swiftly under the reducing conditions of these systems. The TsDPEN ligand plays a critical role in the generation and formatting of the active catalyst including wreaking chiral properties to the so formed catalytic nanoparticles. Kinetic measurements, NMR, UV-visible spectroscopy, circular dichroism (CD) and TEM analyses corroborate this argument.展开更多
Precise fluorescence imaging of single l-DNA molecules for base pair distance analysis requires a superresolution technique, as these distances are on the order of diffraction limit. Individual l-DNA molecules interca...Precise fluorescence imaging of single l-DNA molecules for base pair distance analysis requires a superresolution technique, as these distances are on the order of diffraction limit. Individual l-DNA molecules intercalated with the fluorescent dye YOYO-1 were investigated at subdiffraction spatial resolution by direct stochastic optical reconstruction microscopy（d STORM）. Various dye-to-DNA base pair ratios were imaged by photoswitching YOYO-1 between the fluorescent state and the dark state using two laser sources. The acquired images were reconstructed into a super-resolution image by applying Gaussian fitting to the centroid of the point spread function. By measuring the distances between localized fluorophores, the base pair distances in single DNA molecules for dye-to-DNA base pair ratios of 1：50,1：100, and 1：500 were calculated to be 17.1 0.8 nm, 34.3 2.2 nm, and 170.3 8.1 nm[17_TD$IF], respectively,which were in agreement with theoretical values. These results demonstrate that intercalating dye in a single DNA molecule can be photoswitched without the use of an activator fluorophore, and that super-localization precision at a spatial resolution of 17 nm was experimentally achieved.展开更多
Fluorescent dye （YOYO-I） intercalated with single DNA molecules were investigated via bindingactivated localization microscopy （BALM） at sub-diffraction limit resolutions. Various dye-to-DNA base pair （bp） ratio...Fluorescent dye （YOYO-I） intercalated with single DNA molecules were investigated via bindingactivated localization microscopy （BALM） at sub-diffraction limit resolutions. Various dye-to-DNA base pair （bp） ratios were imaged using the blinking property of YOYO-1 dye under optimum BALM switching buffer conditions. Individual DNA molecules exhibited regular/irregular intercalating phenomena with respect to dye-to-DNA bp ratio. The acquired images were reconstructed into super-resolution images by applying a Gaussian fit to the centroid of the point spread function. The YOYO-1 intercalated with λ-DNA possessed a non-homogeneous region due to the different binding modes of YOYO-1 with λ-DNA. Each binding mode was imaged at the sub-diffraction limit super-resolution. The distance between homogenously localized intercalating dyes within the DNA molecules was measured to be 34nm （n= 10; dye：DNAbp= 1：100） without photocleavage in 50mmol/L β-mercaptoethylamine buffer. The results were similar to those of the theoretical values without photocleavage in the base pairs of single DNA molecules below the diffraction limit. The results paved the way for an in-depth microscopic analysis of molecular variation with single λ-DNA molecules. With this method, it should be possible to analyze the exact base pair breakdown during various stages of cell apoptosis.展开更多
The synthesis and properties of the title complex CH3OCOCH2CH2SnCl3. 2-HOC6H4CH+= NC6H4-3-CH3 are described. It crystallizes from benzene' in the monoclinic space group P2/n with Unit cell dimensions a= 10. 326 (3...The synthesis and properties of the title complex CH3OCOCH2CH2SnCl3. 2-HOC6H4CH+= NC6H4-3-CH3 are described. It crystallizes from benzene' in the monoclinic space group P2/n with Unit cell dimensions a= 10. 326 (3) .b=6. 815(8). c=12. 931 (6) A,β=111. 52(3)°, V=2088. 7(1),A3, Z=4, F(000)= 1040, μ= 16. 31cm-1. Dc =1. 67g/cm3 final R factor is 0. 037 for 3177 observed reflections, I≥3σ(I。). The tin atom in the structure of tile complex exists in a dis tored octahedral geomelry defined by three CI atoms, the C and O atoms of a chelating methoxycarbonylethyl group as well as an O atom derived from the Schiff base ligand.展开更多
The significance of graphene and its two-dimensional(2D)analogous inorganic layered materials especially as hexagonal boron nitride(h-BN)and molybdenum disulphide(MoS2)for“clean energy”applications became apparent o...The significance of graphene and its two-dimensional(2D)analogous inorganic layered materials especially as hexagonal boron nitride(h-BN)and molybdenum disulphide(MoS2)for“clean energy”applications became apparent over the last few years due to their extraordinary properties.In this review article we study the current progress and selected challenges in the syntheses of graphene,h-BN and MoS2 including energy storage applications as supercapacitors and batteries.Various substrates/catalysts(metals/insulator/semiconducting)have been used to obtain graphene,h-BN and MoS2 using different kinds of precursors.The most widespread methods for synthesis of graphene,h-BN and MoS2 layers are chemical vapor deposition(CVD),plasma-enhanced CVD,hydro/solvothermal methods,liquid phase exfoliation,physical methods etc.Current research has shown that graphene,h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries.This review article also contains the discussion on the opportunities and perspectives of these materials(graphene,h-BN and MoS2)in the energy storage fields.We expect that this witen review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene,h-BN and MoS2 layers based materials.展开更多
1 Results The unique structure of chiral ferrocenes allows one to design a variety of chiral phosphine ligands,which are useful tools for metal catalyzed asymmetric reactions.Although some useful chiral ferrocenyl pho...1 Results The unique structure of chiral ferrocenes allows one to design a variety of chiral phosphine ligands,which are useful tools for metal catalyzed asymmetric reactions.Although some useful chiral ferrocenyl phosphine ligands have already been reported,it is still an challenging subject tocreate new ferrocenyl phosphine ligands in order to cover asymmetric reactions in which conventional ligands do not effectively work[1].We happned to discover that 1,5-dilithiation of o-TMS blocked ferrocene 1 pr...展开更多
Microplastics are an emerging threat and a big challenge for the environment.The presence of microplastics(MPs)in water is life-threatening to diverse organisms of aquatic ecosystems.Hence,the scientific community is ...Microplastics are an emerging threat and a big challenge for the environment.The presence of microplastics(MPs)in water is life-threatening to diverse organisms of aquatic ecosystems.Hence,the scientific community is exploring deeper to find treatment and removal options of MPs.Various physical,chemical and biological methods are researched for MPs removal,among which few have shown good efficiency in the laboratory.These methods also have a few limitations in environmental conditions.Other than finding a suitable method,the creation of legal restrictions at a governmental level by imposing policies against MPs is still a daunting task in many countries.This review is an effort to place all effectual MP removal methods in one document to compare the mechanisms,efficiency,advantages,and disadvantages and find the best solution.Further,it also discusses the policies and regulations available in different countries to design an effective global policy.Efforts are also made to discuss the research gaps,recent advancements,and insights in the field.展开更多
Ultrafine powder of CaCu_(2.80)Zn_(0.20)Ti_(4)O_(12)ceramic was prepared using a novel semi-wet method.DTA/TG analysis of dry powder gives pre-information about formation offinal product around 800℃.The formation of ...Ultrafine powder of CaCu_(2.80)Zn_(0.20)Ti_(4)O_(12)ceramic was prepared using a novel semi-wet method.DTA/TG analysis of dry powder gives pre-information about formation offinal product around 800℃.The formation of single phase was confirmed by X-ray diffraction analysis.The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm,respectively.Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic.Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.展开更多
文摘The kinetics of mild steel corrosion in aqueous acetic acid solution has been investigated by weight loss and polarization techniques at 25,35 and 45℃.The weight loss of mild steel at room temperature （25℃） has been found to be quite significant,indicating poor corrosion resistance in acetic acid.The maximum corrosion rate has been observed in 25% acetic acid solution at all three experimental temperatures.The decrease in corrosion rate after attaining a maximum value has been attributed to the deposition of corrosion product on the surface.Anodic polarization curves exhibit active behaviour at each concentration and temperature with a shift towards higher current density region and increased corrosion rates at higher temperatures.The cathodic polarization curves are almost identical irrespective either of the concentration of acetic acid or temperature.The results obtained by both the techniques are in good agreement,while the surface studies support the conclusions drawn from the weight loss method.
文摘Calix resorcinarenes bearing four hydrophobic side chains ( Ar-Rn, Ar-Ph, and Ar-N) orient stably on water oil interface and show high solubilization capacities for organic compounds, such as long chain alcohols, benzene, toluene and dyes. The capacities are high even near the cmc of polyalkylated calix resorcinarenes, but the solubilities of organic compounds(solubilizates) decrease with the increase of the size of the solubilizates. Ar-R 6, with a chain length of six carbons, is the most effective among Ar-R n , Ar-Ph, and Ar-N; 11 fold mol of hexanol is dissolved in 2×10 -3 mol/L Ar-R 6. Moreover, Ar-R n bearing four alkyl side chains solubilizes the chain alcohols of the same chain length mostly. The solubilization capacities are presumably brought by inclusion in a large cavity of the polyalkylated calix resorcinarenes and by an efficient orientation of the solubilizates.
基金Natural Science Foundation of Guangdong Province, China （36837） Financial Expenditure Item of Guangdong Province, China （2003C20520） Post-doctoral Science Fund of China （2005037586） for providing the financial support.
文摘In this study, the oxidative damage of α-terthienyl （α-T） to the Spodoptera litura （SL） cell and its mechanism were investigated. MTT was used to compare the toxicity of α-T and rotenone to the SL cell. The output of malondialdehyde and relative content of glutathione were determined with 2-thiobarbituric acid （TBA） and 5, 5＇-dithio-bis （2-nitrobenzoic acid） （DTNB）, respectively. Transmission electron microscope （TEM） was employed to observe the influence of α-T on the membrane and organelle of the SL cell. The result showed that the IC50 value of α-T to the SL cell was 0.21 μg mL^-1, whereas the corresponding dose of rotenone was 12.25 μg mL^-1. The output of MDA had the same changing tendency with the concentration of α-T, whereas the content of GSH had the negative correlation with it. According to TEM, the cell membrane and karyotheca swelled and couldn＇t retain integrity, the intracellular substances leaked out, unidentified granules appeared in the SL cell. The mitochondria expanded, and the membrane and subcellular organelle were damaged severely. In this study, it was found that after oxidative damage induced by α-T, the output of MDA increased notably, whereas the relative content of GSH decreased. This indicated that the antioxidant ability of cell weakened. The result of TEM implied that the SL cell suffered from oxidative damage under the appointed dose.
基金Supported by the Jiangxi Provincial Department of Education (GJJ08433)Jiangxi Provincial Department of Science and Technology (2008ZD06100)
文摘The title compound,（E）-ethyl 2-（5-（3-methyl-2-butenyloxy）-2-（3-（4-（3-methyl-2-butenyloxy）phenyl） acryloyl） phenoxy）acetate（1）,has been synthesized and characterized by FT-IR and 1H-NMR spectroscopy,ESI-MS,and X-ray single-crystal diffraction.FT-IR,1H-NMR and ESI-MS confirm the functional groups,particularly the ethyl groups in the ester moiety,of the compound.The single-crystal X-ray diffraction has revealed a monoclinic structure,space group P21/n with a = 14.6832（14）,b = 7.7581（7）,c = 23.075（2）,β = 101.670（2）o,V = 2574.2（4） ？3,Z = 4,Dc = 1.235 g/cm,μ = 0.085 mm-1,and F（000） = 1024.The skeleton of chalcone in the molecular structure is coplanar.
文摘Early investigations of dielectric permittivity of rigid polyurethane foams at low frequencies were made on petrochemical-origin foams,mainly by means of parallel plate capacitors.In the present investigation biopolyol was synthesized from Latvia-grown rapeseeds’oil by the transesterification method with triethanolamine,in an environmentally friendly process,without emission of harmful substances,at temperatures 175℃±5℃.Rigid,closed-cell rapeseed oil polyol polyurethane biofoams and petrochemical foams were made ensuring content of the renewable rapeseed oil polyol in ready foams 27 wt.%–29 wt.%.Dielectric permittivity of the polyurethane foams and the underlying monolithic petrochemical-origin polyurethane and biopolyurethane was measured with a non-destructive dielectric spectrometer equipped with a capacitive sensor of one-side access type at 16 discrete frequencies distributed geometrically over the band 10 Hz,…,330 kHz.Permittivity value of the gaseous phase in the closed-cells was estimated to beεg≈1.001 that corresponds to the values,characteristic for the most of gases.Dielectric permittivity of petrochemical polyurethane foams and the mentioned biofoams was compared with permittivity of polyurethane foams from industrial producers Sika JSC and General Plastics Manufacturing Co.Polyurethane foams of the developed formulation exhibit competitive,low dielectric permittivity,not exceeding that of the foams from industrial producers:petrochemical foams up to 550 kg/m^(3) and the mentioned biofoams,comprising the renewable rapeseed oil polyol,up to densities 230–250 kg/m^(3).Considering petrochemical-origin polyurethane foams as a heterogeneous media“Polymer—gaseous phase”,the applicability of the rule of mixture and Maxwell–Garnett equation to model mathematically the dependence of effective dielectric permittivity on the volume fraction of phases was showed.
文摘BaTiO3∶Mn0.006Smx(x=0.001, 0.002, 0.003, 0.004, 0.006 respectively) ceramics were prepared by using sol-gel method and their resistivities at different temperatures were measured. The results showed that Mn element may enhance the PTC characteristics of BaTiO3 ceramics. But the doped Mn element deteriorated the room temperature resistivities of the modified BaTiO3 ceramics which were greater than 105 Ω·m. Then, rare earth element Sm was penetrated into BaTiO3∶Mn0.06Smx ceramics in gaseous state, which largely decreased the room temperature resistivity to 3.20 Ω·m, and appeared as a NTC effect instead of PTC effect. The forming mechanism of NTC effect was explored through analyses of SEM and electric properties of Sm-penetrated BaTiO3∶Mn0.006Smx ceramics.
基金This work was supported by the National Natural Science Foundation of China (No. 20076038 and No. 20204014).
文摘The correlation between shape and size of linear chains on the simple cubic lattice is investigated using a dynamicMonte Carlo technique. A positive correlation between the asphericity parameter A and the square of the end-to-end distanceR^2, as well as that between A and the square of the radius of gyration S^2, is found for both RW and SAW chains, indicatingthat a chain conformation of small size is usually more spherical than one of large size. The result can explain why the shapeof the SAW chain deviate much more from a sphere than that of the RW chain, and can also explain the similar dependenceof size and shape on chain stiffness and on the distance of the first bead of a chain from an infinitely large flat surface.
文摘A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Nos.2019R1A2C2002556 and 2020R1C1C1009668)supported by Nano-Material Technology Development Program through the NRF funded by the Ministry of Science,ICT and Future Planning(No.2009-0082580).
文摘A wavelength-dependent three-dimensional(3D)superlocalization imaging method on gold nanoislands(GNIs)chip was developed as a supersensitive single-molecule thyroid-stimulating hormone(TSH)nanobiosensor.Scattered and fluorescent signals from gold nanoislands on the substrate and quantum dots(QDs)nanoprobes were simultaneously isolated and acquired within an evanescent field layer generated by total internal reflection(TIR)of incident light using a dual-view device.The 3D TIR fluorescence images of TSH-bound QDs on the GNIs were obtained using z-axis optical sectioning at 10nm intervals before/after immunoreaction to identify the optimal conditions for detection.The localized centroid position of QD nanoprobes and GNI were distinguished at a subdiffraction limit resolution using 3D Gaussian fitting to the point spread function.The QD TSH nanobiosensor using wavelength-dependent 3D TIR fluorescence-based single-molecule localization microscopy(3D TIRF-SLM)imaging technique showed an excellent detection limit of 90 yoctomoles(~54 molecules)and a wide linear dynamic range of 1.14 zmol/L-100 pmol/L for TSH.The detection sensitivity was about 4.4×10^(9)times higher than conventional enzyme-linked immunosorbent assay and could successfully quantify TSH in human serum.The wavelength-dependent 3D TIRF-SLM technique may emerge as a reliable platform for ultrahigh-sensitive nanobiosensors at the single-molecule level and early diagnosis with quantification of disease-related ultra-tracebiomolecules.
文摘This article deals with the study of the viscoelastic and thermal properties of polyurethane (PU) rigid foamsfrom biobased and recycled components. Rapeseed oil (RO) and recycled poly(ethylene terephthalate)(PET) were used to synthesize PU polyols. Addition of adipic acid (ADA) to polyol resulted in improvedthermal and viscoelastic properties of foam materials. ADA content was varied from 1 to 6 wt%. Results ofthe dynamic mechanical spectra indicate an increase of the storage modulus E′ and the loss modulus E″ inthe whole temperature range for specimens with higher loading of ADA. In addition, damping factor shiftedto higher temperatures, but damping intensity remained almost unaffected by the compositions. Scanningelectron microscopy of the foams’ cross sections testified that the average cells’ size of 110 mm was unaffectedby the ADA content in polyol.
文摘The widespread precatalyst (prepared in-situ or ex-situ) (arene) RuTsDPEN advocated for highly effectual asymmetric transfer hydrogenation (ATH) reactions with 2-propanol as hydrogen donor at ambient conditions, is proven to be unstable under the strong reducing conditions prevailing in the reaction mixtures (blend of alcohol and a base such as KOH). We assert that the true catalysts are the ruthenium metal nanoclusters formed swiftly under the reducing conditions of these systems. The TsDPEN ligand plays a critical role in the generation and formatting of the active catalyst including wreaking chiral properties to the so formed catalytic nanoparticles. Kinetic measurements, NMR, UV-visible spectroscopy, circular dichroism (CD) and TEM analyses corroborate this argument.
基金supported by a grant from Kyung Hee University in 2015(No.KHU-20150618)
文摘Precise fluorescence imaging of single l-DNA molecules for base pair distance analysis requires a superresolution technique, as these distances are on the order of diffraction limit. Individual l-DNA molecules intercalated with the fluorescent dye YOYO-1 were investigated at subdiffraction spatial resolution by direct stochastic optical reconstruction microscopy（d STORM）. Various dye-to-DNA base pair ratios were imaged by photoswitching YOYO-1 between the fluorescent state and the dark state using two laser sources. The acquired images were reconstructed into a super-resolution image by applying Gaussian fitting to the centroid of the point spread function. By measuring the distances between localized fluorophores, the base pair distances in single DNA molecules for dye-to-DNA base pair ratios of 1：50,1：100, and 1：500 were calculated to be 17.1 0.8 nm, 34.3 2.2 nm, and 170.3 8.1 nm[17_TD$IF], respectively,which were in agreement with theoretical values. These results demonstrate that intercalating dye in a single DNA molecule can be photoswitched without the use of an activator fluorophore, and that super-localization precision at a spatial resolution of 17 nm was experimentally achieved.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science, and Technology(No. 2015R1A2A2A01003839)
文摘Fluorescent dye （YOYO-I） intercalated with single DNA molecules were investigated via bindingactivated localization microscopy （BALM） at sub-diffraction limit resolutions. Various dye-to-DNA base pair （bp） ratios were imaged using the blinking property of YOYO-1 dye under optimum BALM switching buffer conditions. Individual DNA molecules exhibited regular/irregular intercalating phenomena with respect to dye-to-DNA bp ratio. The acquired images were reconstructed into super-resolution images by applying a Gaussian fit to the centroid of the point spread function. The YOYO-1 intercalated with λ-DNA possessed a non-homogeneous region due to the different binding modes of YOYO-1 with λ-DNA. Each binding mode was imaged at the sub-diffraction limit super-resolution. The distance between homogenously localized intercalating dyes within the DNA molecules was measured to be 34nm （n= 10; dye：DNAbp= 1：100） without photocleavage in 50mmol/L β-mercaptoethylamine buffer. The results were similar to those of the theoretical values without photocleavage in the base pairs of single DNA molecules below the diffraction limit. The results paved the way for an in-depth microscopic analysis of molecular variation with single λ-DNA molecules. With this method, it should be possible to analyze the exact base pair breakdown during various stages of cell apoptosis.
基金project supported by the National Natural Scicnces Foundation of China
文摘The synthesis and properties of the title complex CH3OCOCH2CH2SnCl3. 2-HOC6H4CH+= NC6H4-3-CH3 are described. It crystallizes from benzene' in the monoclinic space group P2/n with Unit cell dimensions a= 10. 326 (3) .b=6. 815(8). c=12. 931 (6) A,β=111. 52(3)°, V=2088. 7(1),A3, Z=4, F(000)= 1040, μ= 16. 31cm-1. Dc =1. 67g/cm3 final R factor is 0. 037 for 3177 observed reflections, I≥3σ(I。). The tin atom in the structure of tile complex exists in a dis tored octahedral geomelry defined by three CI atoms, the C and O atoms of a chelating methoxycarbonylethyl group as well as an O atom derived from the Schiff base ligand.
基金R.K.acknowledges Japan Society for the Promotion of Science(JSPSStandard)for international postdoctoral fellowship(P18063)and this research work was supported by JSPS KAKENHI Grant No.18F18063.A.M.acknowledges the financial support from JSPS KAKENHI Grant JP-18H03841 and JSPS KAKENHI Grant JP-17K18985.R.K.and A.M.would like to thanks Toyohashi University of Technology,Toyohashi,Aichi,Japan for providing the necessarily support and facilities to complete this work.S.S.acknowledges DST-SERB,India for the national postdoctoral fellowship(NPDF File No.PDF/2017/000328).D.P.S.acknowledges with gratitude the financial support from Millennium Institute for Research in Optics(MIRO),CHILE.R.K.would like to dedicate this work to the memory of late Prof.Yoshiyuki Suda.
文摘The significance of graphene and its two-dimensional(2D)analogous inorganic layered materials especially as hexagonal boron nitride(h-BN)and molybdenum disulphide(MoS2)for“clean energy”applications became apparent over the last few years due to their extraordinary properties.In this review article we study the current progress and selected challenges in the syntheses of graphene,h-BN and MoS2 including energy storage applications as supercapacitors and batteries.Various substrates/catalysts(metals/insulator/semiconducting)have been used to obtain graphene,h-BN and MoS2 using different kinds of precursors.The most widespread methods for synthesis of graphene,h-BN and MoS2 layers are chemical vapor deposition(CVD),plasma-enhanced CVD,hydro/solvothermal methods,liquid phase exfoliation,physical methods etc.Current research has shown that graphene,h-BN and MoS2 layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries.This review article also contains the discussion on the opportunities and perspectives of these materials(graphene,h-BN and MoS2)in the energy storage fields.We expect that this witen review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene,h-BN and MoS2 layers based materials.
文摘1 Results The unique structure of chiral ferrocenes allows one to design a variety of chiral phosphine ligands,which are useful tools for metal catalyzed asymmetric reactions.Although some useful chiral ferrocenyl phosphine ligands have already been reported,it is still an challenging subject tocreate new ferrocenyl phosphine ligands in order to cover asymmetric reactions in which conventional ligands do not effectively work[1].We happned to discover that 1,5-dilithiation of o-TMS blocked ferrocene 1 pr...
文摘Microplastics are an emerging threat and a big challenge for the environment.The presence of microplastics(MPs)in water is life-threatening to diverse organisms of aquatic ecosystems.Hence,the scientific community is exploring deeper to find treatment and removal options of MPs.Various physical,chemical and biological methods are researched for MPs removal,among which few have shown good efficiency in the laboratory.These methods also have a few limitations in environmental conditions.Other than finding a suitable method,the creation of legal restrictions at a governmental level by imposing policies against MPs is still a daunting task in many countries.This review is an effort to place all effectual MP removal methods in one document to compare the mechanisms,efficiency,advantages,and disadvantages and find the best solution.Further,it also discusses the policies and regulations available in different countries to design an effective global policy.Efforts are also made to discuss the research gaps,recent advancements,and insights in the field.
文摘Ultrafine powder of CaCu_(2.80)Zn_(0.20)Ti_(4)O_(12)ceramic was prepared using a novel semi-wet method.DTA/TG analysis of dry powder gives pre-information about formation offinal product around 800℃.The formation of single phase was confirmed by X-ray diffraction analysis.The average particle size of sintered powder of the ceramic obtained from XRD and Transmission electron microscopy was found 59 nm and 102 nm,respectively.Energy Dispersive X-ray studies confirm the stoichiometry of the synthesized ceramic.Dielectric constant of the ceramic was found to be 2617 at room temperature at 1 kHz.
