To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ me...To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ method for synthesising Au nanoparticles on ZIF-67.In this study,an Au@ZIF-67 composite humidity-sensitive material was combined with flexible polyethylene terephthalate interdigitated electrodes to create an Au@ZIF-67 flexible humidity sensor.The prepared samples were characterised using X-ray diffraction,X-ray photoelectron spectroscopy,and transmission electron microscopy.The humidity-sensitive properties of the sensor were investigated,and its monitoring capabilities in applications involving respiration,gestures,skin,and baby diapers were tested.The experimental results indicate that compared with a pure ZIF-67 humidity sensor,the Au@ZIF-67(0.1Au@Z)flexible humidity sensor exhibits a 158.07%decrease in baseline resistance and a 51.66%increase in sensitivity to 95%relative humidity,and the hysteresis,response time,and recovery time are significantly reduced.Furthermore,the sensor exhibits excellent characteristics such as high resolution,repeatability,and stability.The obtained results regarding the material properties,humidity sensitivity,and practical application of non-contact humidity monitoring demonstrate that the prepared sensors exhibit excellent and comprehensive performance,indicating their broad prospects in wearable medical devices,wireless Internet of Things,humidity detection in complex environments,and intelligent integrated systems.展开更多
Bio-silica issued from diatom, a microalgae, is attracted increasing attention in material science thanks to its peculiar nanoarchitecture and related properties with versatile applications. The present work is a deep...Bio-silica issued from diatom, a microalgae, is attracted increasing attention in material science thanks to its peculiar nanoarchitecture and related properties with versatile applications. The present work is a deep analysis on morphological and chemical properties of bio-silica issued from fossil origin (diatomaceous earth) and living one (algal paste). An optimization in purification protocol was performed to obtain multiparous bio-silica from its raw media with keeping its original shape entirely. Multiple characterization methods as scanning electronic microscopy (SEM), infrared spectroscopy, x-ray diffraction (DRX), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption and inverse gas chromatography (IGC), were used to check the purification protocol efficiency as well as to gather accurate information on morphology and chemical composition of diatom material obtained in large amount.展开更多
Unialgal explants from Luminaria digitata, and from a variety of red algae were obtained by hand removing the visible epiphytes, and stirring the tissue in the presence of glass beads. Two antibiotic mixtures were fou...Unialgal explants from Luminaria digitata, and from a variety of red algae were obtained by hand removing the visible epiphytes, and stirring the tissue in the presence of glass beads. Two antibiotic mixtures were found to be efficient in removing the contaminating fungi and bacteria from the algae. The procedure proved suitable as a primary step in the tissue culture of the investigated species.展开更多
A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） i...A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） in a simulation chamber.Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone.Three HCHO ro-vibrational line intensities （at 2909.71,2912.09 and 2914.46 cm-1） possibly used by TDLAS were calibrated by FT-IR spectra simultaneously recorded in the 1600–3200 cm-1 domain during ethene ozonolysis,enabling the on-line deduction of the varying concentration for HCHO in formation.The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database.In addition,the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated.The TDLAS performances were also assessed,leading to a 2σ detection limit of 88 ppt in volume mixing ratio with a response time of 60 sec at 30 Torr and 294 K for 112 m optical path.As part of this work,the room-temperature rate constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.展开更多
The rate constants for the C1 atom reaction with three branched ketones have been measured at 298 ± 2 K and 760 Torr using the relative rate method in the absence of NO. The rate constants values obtained （in un...The rate constants for the C1 atom reaction with three branched ketones have been measured at 298 ± 2 K and 760 Torr using the relative rate method in the absence of NO. The rate constants values obtained （in units of 10^-10 cm^3/（molecule.sec）） are： k（2-methyl-3-pentanone） = 1.07 ± 0.26, k（3-methyl-2-pentanone） =1.21 ± 0.26, and k（4-methyl-2-pentanone） = 1.35 ± 0.27. Combining the chemical kinetic data obtained by this study with those reported for other ketones, a revised Structure Activity Relationship （SAR） parameter and R group reactivity （kR of R（O）R＇ and CHx （x = 1, 2, 3） group reactivity （kCHx） toward C1 atoms were proposed. In addition, the products from the three reactions in the presence of NO were also identified and quantified by using PTR-ToF-MS and GC-FID, and the yields of the identified products are： acetone （39% ± 8%） ＋ ethanal （78% ± 12%）, 2-butanone （22% ± 2%） ＋ ethanal （75% ± 10%） ＋ propanal （14% ± 1%） and acetone （26% ± 3%） ＋ 2-methylpmpanal （24% ± 2%）, for C1 atoms reaction with 2-methyl-3-pentanone, 3-methyl-2-pentanone and 4-methyl-2-pentanone, respectively. Based on the obtained results, the reaction mechanisms of C1 atoms with these three ketones are proposed.展开更多
Biocomposite films prepared with melt compounding and film blowing have become a new trend in plastic research to deliver more eco-friendly packages.Polylactic acid(PLA)was melt compounded with minimally processed dat...Biocomposite films prepared with melt compounding and film blowing have become a new trend in plastic research to deliver more eco-friendly packages.Polylactic acid(PLA)was melt compounded with minimally processed date palm leaf fiber(DPLF)and converted into films by blown film extrusion.The compounding was done in order to enhance the film mechanical properties in one hand,and to decrease the film production cost in the other hand.In this present study,a reference PLA film and films with 1%,2%,and 5%of DPLF(weight%)were produced with different process parameters.The spatial variations in films thickness and lay flat width indicate that the addition of DPLF up to 2%enhances the bubble stability for the tested process parameters.However,the composite with 5%DPLF shows nearly the same processability window as the neat PLA.The structural and mechanical characterizations of films suggest a reinforcing effect of the PLA matrix up to 2%of fiber(with an optimum at 1%).Larger DPLF loading leads to depressed and more anisotropic mechanical properties,related to an increased density of defects at the fiber-PLA fragile interface and to a DPLF-induced enhanced PLA thermal degradation and amorphous phase orientation.展开更多
Rate coefficients for the reaction of N03 radicals with 6 unsaturated volatile organic compounds(VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate metho...Rate coefficients for the reaction of N03 radicals with 6 unsaturated volatile organic compounds(VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method.The resulting rate coefficients were determined for isoprene,2-carene,3-carene,methyl vinyl ketone(MVK),methacrolein(MACR)and crotonaldehyde(CA),as(6.6±0.8)×10-13,(1.8±0.6)×10-11,(8.7±0.5)×10-12,(1.24±1.04)×10-16,(3.3±0.9)×10-15 and(5.7±1.2)×10-15 cm3/(molecule·sec),respectively.The experiments indicate that NO3 radical reactions with all the studied unsaturated VOGs proceed through addition to the olefinic bond,however,it indicates that the introduction of a carbonyl group into unsaturated VOGs can deactivate the neighboring olefinic bond towards reaction with the NO3 radical,which is to be expected since the presence of these electronwithdrawing substituents will reduce the electron density in the π orbitals of the alkenes,and will therefore reduce the rate coefficient of these electrophilic addition reactions.In addition,we investigated the product formation from the reactions of 2-carene and 3-carene with the NO3 radical.Qualitative identification of an epoxide(C10H16OH+),caronaldehyde(C10H16O2 H+) and nitrooxy-ketone(C10H16O4 NH+) was achieved using a proton transfer reaction time-of-flight mass spectrometer(PTR-TOF-MS) and a reaction mechanism is proposed.展开更多
Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability dis...Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.展开更多
Strontium-britholites whose chemical formula was Sr10-xLax（PO4）6-x（SiO4）xF2, where x=0, 1, 2, and 4 were prepared by solid state reaction. The structural refinement carried out using the Rietveld method indicated ...Strontium-britholites whose chemical formula was Sr10-xLax（PO4）6-x（SiO4）xF2, where x=0, 1, 2, and 4 were prepared by solid state reaction. The structural refinement carried out using the Rietveld method indicated that La^3＋ ions were located into the two sites with a strong preference for metal （2） sites especially for low contents. A progressive shift of the F position along the c-axis outside the centre of the triangle formed by metal （2）-atoms was observed with the increase of x. The infrared and Raman spectra exhibited the characteristic vibration modes of PO4 and SiO4groups confirming the incorporation of this last group into the apatite structure. The 295i MAS-NMR spectra exhibited one resonance peak confirming the data obtained by X-ray diffraction, indicating that P and Si were located in the same crystallographic site.展开更多
We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanopart...We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanoparticles.These specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ content.The YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 matrix.The decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional supercooling.Furthermore,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved oxygen.Finally,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.展开更多
The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound ...The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound has been characterized by UV-vis., IR, MSI MS and 1H NMR spectroscopy. The UV-vis data and especially the proton NMR results, for the isolated product, indicated that complex 1 is a Co(II) mesoporphyrin derivative.The X-ray molecular structure of the title compound bis(2-aminophenol) (tetraphenylporphyrinato) cobalt(II) has been determined. This structure is the first one reported of a metalloporphyrin with a 2-aminophenol axial ligand species. The central metal is hexacoordinated by the four nitrogen atoms of the pyrrole rings and the nitrogen atoms of the two Hon trans axial ligands.展开更多
The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm&...The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of ther- mal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.展开更多
Recent studies have demonstrated a new role for Klf10, a Krüppel-like transcription factor, in skeletal muscle, specifically relating to mitochondrial function. Thus, it was of interest to analyze additional tiss...Recent studies have demonstrated a new role for Klf10, a Krüppel-like transcription factor, in skeletal muscle, specifically relating to mitochondrial function. Thus, it was of interest to analyze additional tissues that are highly reliant on optimal mitochondrial function such as the cerebellum and to decipher the role of Klf10 in the functional and structural properties of this brain region. In vivo (magnetic resonance imaging and localized spectroscopy, behavior analysis) and in vitro (histology, spectroscopy analysis, enzymatic activity) techniques were applied to comprehensively assess the cerebellum of wild type (WT) and Klf10 knockout (KO) mice. Histology analysis and assessment of locomotion revealed no significant difference in Klf10 KO mice. Diffusion and texture results obtained using MRI revealed structural changes in KO mice characterized as defects in the organization of axons. These modifications may be explained by differences in the levels of specific metabolites (myo-inositol, lactate) within the KO cerebellum. Loss of Klf10 expression also led to changes in mitochondrial activity as reflected by a significant increase in the activity of citrate synthase, complexes I and IV. In summary, this study has provided evidence that Klf10 plays an important role in energy production and mitochondrial function in the cerebellum.展开更多
Both the primed in situ(PRINS)and the peptide nucleic acid-fluorescence in situ hybridization(PNA-FISH) techniques constitute alternatives to the conventional(fluorescence in situ hybridization,FISH)procedure for chro...Both the primed in situ(PRINS)and the peptide nucleic acid-fluorescence in situ hybridization(PNA-FISH) techniques constitute alternatives to the conventional(fluorescence in situ hybridization,FISH)procedure for chro- mosomal investigations.The PRINS reaction is based on the use of a DNA polymerase and labeled nucleotide in an in situ primer extension reaction.Peptide nucleic acid probes are synthetic DNA analogs with uncharged polyamide backbones.The two procedures present several advantages(specificity,rapidity and discriminating ability)that make them very attractive for cytogenetic purposes.Their adaptation to human spermatozoa has allowed the development of new and fast procedures for the chromosomal screening of male gametes and has provided efficient complements to FISH for in situ assessment of aneuploidy in male gametes.(Asian J Androl 2006 Jul;8:387-392)展开更多
Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance i...Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance imaging(MRI)and photodynamic therapy(PDT).The complexes Mn-1,Mn-2,and Mn-3 are highly water-soluble,and their relaxivities range between 10 and 15 mM^(-1) s^(-1),at 20-80 MHz and 298 K,2-3 times higher than that of commercial Gd(III)-based agents.The complexes containing carboxylate(Mn-2)or alcoholic(Mn-3)side chains in the para position are endowed with higher relaxivities and have also shown efficient photoinduced DNA cleavage and singlet oxygen(^(1)O_(2))generation.Mn-3 with stronger photoinduced DNA cleavage has also revealed stabilizing and binding activities for G4 DNA,at a similar level as the known G4 binder Mn-TMPyP4.Nevertheless,the G4-binding activity of Mn-3 was nonspecific.Preliminary tests evidenced photocytotoxicity of Mn-3 on HeLa cells without a significant effect in the absence of light.Altogether,these results underline the potential of such water-soluble Mn(III)-porphyrins for the development of multimodal approaches combining MRI and PDT.展开更多
In recent years,(0001)twist grain boundaries(BTGBs)located in primary α grain clusters were identified as fatigue crack nucleation sites in different Ti alloys.In the present study,crack initiation was investigated i...In recent years,(0001)twist grain boundaries(BTGBs)located in primary α grain clusters were identified as fatigue crack nucleation sites in different Ti alloys.In the present study,crack initiation was investigated in a bimodal Ti-5Al-4 V alloy subjected to low-cycle fatigue and dwell-fatigue loadings at room temperature.The low fraction of primary α grains was not associated with a lack of sensitivity to BTGB cracking.Transmission electron microscopy and electron back-scattered diffraction were used to characterize BTGBs in the initial microstructure.The fatigue mechanisms were then analyzed with a focus on dislocation activity.α_(p) grains adjacent to cracked BTGBs contained a high dislocation density.It was primarily composed of planar slip bands of <a> dislocations.In addition,<c+a>dislocations were noticed in the vicinity of cracked BTGBs.They supposedly pertain to crack tip plasticity during growth,and no evidence of a role of an incoming slip event in crack nucleation was obtained.Also,basal slip bands extending across adjacent grains were found to emerge from BTGBs.This feature provides an easier path for crack extension when growth along the grain boundary becomes difficult owing to a deviation from the basal plane.Atom probe tomography analyses evidenced V and Fe segregation at a grain boundary with a significant deviation from the BTGB configuration.This suggests a possible contribution of local solute segregation to the high cracking resistance of general α_(p)/α_(p) grain boundaries.This work provides new insights into the mechanisms involved in cracking of BTGB in Ti alloys subjected to cyclic loadings.展开更多
Despite numerous efforts from numerical approaches to complement experimental measurements,several fundamental challenges have still hindered one’s ability to truly provide an atomistic picture of the nucleation proc...Despite numerous efforts from numerical approaches to complement experimental measurements,several fundamental challenges have still hindered one’s ability to truly provide an atomistic picture of the nucleation process in nanocrystals.Among them,our study resolves three obstacles:(1)Machinelearning force fields including long-range interactions able to capture the finesse of the underlying atomic interactions,(2)Data-driven characterization of the local ordering in a complex structural landscape associated with several crystal polymorphs and(3)Comparing results from a large range of temperatures using both brute-force and rare-event sampling.Altogether,our simulation strategy has allowed us to study zinc oxide crystallization from nano-droplet melt.Remarkably,our results show that different nucleation pathways compete depending on the investigated degree of supercooling.展开更多
基金supported by the Natural Science Project of Zhengzhou Science and Technology Bureau(No.21ZZXTCX12)the Key Research and Development Program of Henan Province(No.221111220300)+1 种基金the Key Program of the National Natural Science Foundation of China(No.62333013)the Youth Backbone Teacher Training Program of Henan University of Technology(No.21420154).
文摘To facilitate real-time monitoring and recording of humidity in the environment and to satisfy the requirement for strain performance in certain applications(such as wearable devices),this paper proposes an in-situ method for synthesising Au nanoparticles on ZIF-67.In this study,an Au@ZIF-67 composite humidity-sensitive material was combined with flexible polyethylene terephthalate interdigitated electrodes to create an Au@ZIF-67 flexible humidity sensor.The prepared samples were characterised using X-ray diffraction,X-ray photoelectron spectroscopy,and transmission electron microscopy.The humidity-sensitive properties of the sensor were investigated,and its monitoring capabilities in applications involving respiration,gestures,skin,and baby diapers were tested.The experimental results indicate that compared with a pure ZIF-67 humidity sensor,the Au@ZIF-67(0.1Au@Z)flexible humidity sensor exhibits a 158.07%decrease in baseline resistance and a 51.66%increase in sensitivity to 95%relative humidity,and the hysteresis,response time,and recovery time are significantly reduced.Furthermore,the sensor exhibits excellent characteristics such as high resolution,repeatability,and stability.The obtained results regarding the material properties,humidity sensitivity,and practical application of non-contact humidity monitoring demonstrate that the prepared sensors exhibit excellent and comprehensive performance,indicating their broad prospects in wearable medical devices,wireless Internet of Things,humidity detection in complex environments,and intelligent integrated systems.
文摘Bio-silica issued from diatom, a microalgae, is attracted increasing attention in material science thanks to its peculiar nanoarchitecture and related properties with versatile applications. The present work is a deep analysis on morphological and chemical properties of bio-silica issued from fossil origin (diatomaceous earth) and living one (algal paste). An optimization in purification protocol was performed to obtain multiparous bio-silica from its raw media with keeping its original shape entirely. Multiple characterization methods as scanning electronic microscopy (SEM), infrared spectroscopy, x-ray diffraction (DRX), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), nitrogen adsorption and inverse gas chromatography (IGC), were used to check the purification protocol efficiency as well as to gather accurate information on morphology and chemical composition of diatom material obtained in large amount.
文摘Unialgal explants from Luminaria digitata, and from a variety of red algae were obtained by hand removing the visible epiphytes, and stirring the tissue in the presence of glass beads. Two antibiotic mixtures were found to be efficient in removing the contaminating fungi and bacteria from the algae. The procedure proved suitable as a primary step in the tissue culture of the investigated species.
基金supported by the European Commission through the 7th Framework Programme under the grant agreement #228335 (EUROCHAMP-2 Project)by the French CNRS-INSU Programme National de Chimie Atmosphrique
文摘A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） in a simulation chamber.Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone.Three HCHO ro-vibrational line intensities （at 2909.71,2912.09 and 2914.46 cm-1） possibly used by TDLAS were calibrated by FT-IR spectra simultaneously recorded in the 1600–3200 cm-1 domain during ethene ozonolysis,enabling the on-line deduction of the varying concentration for HCHO in formation.The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database.In addition,the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated.The TDLAS performances were also assessed,leading to a 2σ detection limit of 88 ppt in volume mixing ratio with a response time of 60 sec at 30 Torr and 294 K for 112 m optical path.As part of this work,the room-temperature rate constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.
基金supported by Labex Voltaire (ANR-10-LABX-100-01), ARD PIVOTS program (supported by the Centre-Val de Loire regional council)the European Union's Horizon 2020 Research and Innovation Programme through the EUROCHAMP2020 Infrastructure Activity under grant agreement No. 730997+1 种基金the China Scholarship Council for the financial supportsupported by the Natural Science Foundation of China (No. 41305124)
文摘The rate constants for the C1 atom reaction with three branched ketones have been measured at 298 ± 2 K and 760 Torr using the relative rate method in the absence of NO. The rate constants values obtained （in units of 10^-10 cm^3/（molecule.sec）） are： k（2-methyl-3-pentanone） = 1.07 ± 0.26, k（3-methyl-2-pentanone） =1.21 ± 0.26, and k（4-methyl-2-pentanone） = 1.35 ± 0.27. Combining the chemical kinetic data obtained by this study with those reported for other ketones, a revised Structure Activity Relationship （SAR） parameter and R group reactivity （kR of R（O）R＇ and CHx （x = 1, 2, 3） group reactivity （kCHx） toward C1 atoms were proposed. In addition, the products from the three reactions in the presence of NO were also identified and quantified by using PTR-ToF-MS and GC-FID, and the yields of the identified products are： acetone （39% ± 8%） ＋ ethanal （78% ± 12%）, 2-butanone （22% ± 2%） ＋ ethanal （75% ± 10%） ＋ propanal （14% ± 1%） and acetone （26% ± 3%） ＋ 2-methylpmpanal （24% ± 2%）, for C1 atoms reaction with 2-methyl-3-pentanone, 3-methyl-2-pentanone and 4-methyl-2-pentanone, respectively. Based on the obtained results, the reaction mechanisms of C1 atoms with these three ketones are proposed.
文摘Biocomposite films prepared with melt compounding and film blowing have become a new trend in plastic research to deliver more eco-friendly packages.Polylactic acid(PLA)was melt compounded with minimally processed date palm leaf fiber(DPLF)and converted into films by blown film extrusion.The compounding was done in order to enhance the film mechanical properties in one hand,and to decrease the film production cost in the other hand.In this present study,a reference PLA film and films with 1%,2%,and 5%of DPLF(weight%)were produced with different process parameters.The spatial variations in films thickness and lay flat width indicate that the addition of DPLF up to 2%enhances the bubble stability for the tested process parameters.However,the composite with 5%DPLF shows nearly the same processability window as the neat PLA.The structural and mechanical characterizations of films suggest a reinforcing effect of the PLA matrix up to 2%of fiber(with an optimum at 1%).Larger DPLF loading leads to depressed and more anisotropic mechanical properties,related to an increased density of defects at the fiber-PLA fragile interface and to a DPLF-induced enhanced PLA thermal degradation and amorphous phase orientation.
基金supported by Labex Voltaire(No.ANR-10-LABX100-01)the French National Research Agency(Agence Nationale de la Recherche)and the Research Grants Council(ANR-RGC)program(project ANR-16-CE01-0013)+2 种基金ARD PIVOTS program(Ambition Recherche Développement Plateformes d’Innovation,de Valorisation,d’Optimisation,Technologiques environnmentale S,supported by the centre-Val de Loire regional council)funding from the European Union’s Horizon 2020 research and innovation program through the EUROCHAMP-2020 Infrastructure Activity(No.730997)the Marie Sk?odowska Curie Actions Programme(No.690958)(MARSU)
文摘Rate coefficients for the reaction of N03 radicals with 6 unsaturated volatile organic compounds(VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method.The resulting rate coefficients were determined for isoprene,2-carene,3-carene,methyl vinyl ketone(MVK),methacrolein(MACR)and crotonaldehyde(CA),as(6.6±0.8)×10-13,(1.8±0.6)×10-11,(8.7±0.5)×10-12,(1.24±1.04)×10-16,(3.3±0.9)×10-15 and(5.7±1.2)×10-15 cm3/(molecule·sec),respectively.The experiments indicate that NO3 radical reactions with all the studied unsaturated VOGs proceed through addition to the olefinic bond,however,it indicates that the introduction of a carbonyl group into unsaturated VOGs can deactivate the neighboring olefinic bond towards reaction with the NO3 radical,which is to be expected since the presence of these electronwithdrawing substituents will reduce the electron density in the π orbitals of the alkenes,and will therefore reduce the rate coefficient of these electrophilic addition reactions.In addition,we investigated the product formation from the reactions of 2-carene and 3-carene with the NO3 radical.Qualitative identification of an epoxide(C10H16OH+),caronaldehyde(C10H16O2 H+) and nitrooxy-ketone(C10H16O4 NH+) was achieved using a proton transfer reaction time-of-flight mass spectrometer(PTR-TOF-MS) and a reaction mechanism is proposed.
基金the program "Small Systems Nonequilibrium Fluctuations,Dynamics and Stochastics,and Anomalous Behavior" of the Kavli Institute for Theoretical Physics China at the Chinese Academy of Sciences(KITPC),held in Bejing in July 2013funded by the French Institut de la Recherche M'edicale,under Grant MICROMEGAS PC201104+1 种基金the French Institut National du Cancer,under Grant INCa-5960the French Agence Nationale de la Recherche under Grant No.ANR-13-BSV5-0010-03.UPMC belongs to Sorbonne Universit'es
文摘Investigating average thermodynamic quantities is not sufficient to understand conformational transitions of a finite-size polymer. We propose that such transitions are better described in terms of the probability distribution of some finite-size order parameter, and the evolution of this distribution as a control parameter varies. We demonstrate this claim for the coil-globule transition of a linear polymer and its mapping onto a two-state model. In a biological context, polymer models delineate the physical constraints experienced by the genome at different levels of organization,from DNA to chromatin to chromosome. We apply our finite-size approach to the formation of plectonemes in a DNA segment submitted to an applied torque and the ensuing helix-coil transition that can be numerically observed, with a coexistence of the helix and coil states in a range of parameters. Polymer models are also essential to analyze recent in vivo experiments providing the frequency of pairwise contacts between genomic loci. The probability distribution of these contacts yields quantitative information on the conformational fluctuations of chromosome regions. The changes observed in the shape of the distribution when the cell type or the physiological conditions vary may reveal an epigenetic modulation of the conformational constraints experienced by the chromosomes.
基金the Ministry of Higher Education, Scientific Research and Technology (Tunisian)
文摘Strontium-britholites whose chemical formula was Sr10-xLax（PO4）6-x（SiO4）xF2, where x=0, 1, 2, and 4 were prepared by solid state reaction. The structural refinement carried out using the Rietveld method indicated that La^3＋ ions were located into the two sites with a strong preference for metal （2） sites especially for low contents. A progressive shift of the F position along the c-axis outside the centre of the triangle formed by metal （2）-atoms was observed with the increase of x. The infrared and Raman spectra exhibited the characteristic vibration modes of PO4 and SiO4groups confirming the incorporation of this last group into the apatite structure. The 295i MAS-NMR spectra exhibited one resonance peak confirming the data obtained by X-ray diffraction, indicating that P and Si were located in the same crystallographic site.
基金financially supported by the Ministry of Trade,Industry&Energy(MOTIE),Korea Institute for Advancement of Technology(KIAT)[grant number-N0002609]the National Research Foundation(NRF)of Korea[grant number 2020R1A2C2008416]。
文摘We report on the microstructure and the strengthening mechanisms of additively manufactured parts fabricated by directed energy deposition of Ti-6Al-4V(Ti64)powders blended with yttria-stabilized zirconia(YSZ)nanoparticles.These specimens showed refined microstructures as compared to bare as-deposited Ti64,where theαand columnar priorβgrain sizes decreased with increasing YSZ content.The YSZ nanoparticles decomposed during the deposition process and led to the formation of yttrium oxide and some excess oxygen in the Ti64 matrix.The decrease in the sizes of the priorβgrains could be attributed to the increasing amount of dissolved oxygen and yttrium,which promoted constitutional supercooling.Furthermore,the reduction in the size of theαgrains could be ascribed to a shift of the onset of theβ→α+βtransformation to a higher temperature and shorter time with increasing concentration of dissolved oxygen.Finally,the contributions of the underlying strengthening mechanisms for the as-deposited specimens were quantitatively determined.
文摘The reaction of the cobalt(II) meso-tetraphenylporphyrin (TPP) starting material with an excess of 2-aminophenol (Hon) in organic solvents, yields the cobalt(II) porphyrin species [CoII(TPP)(Hon)2] (1). This compound has been characterized by UV-vis., IR, MSI MS and 1H NMR spectroscopy. The UV-vis data and especially the proton NMR results, for the isolated product, indicated that complex 1 is a Co(II) mesoporphyrin derivative.The X-ray molecular structure of the title compound bis(2-aminophenol) (tetraphenylporphyrinato) cobalt(II) has been determined. This structure is the first one reported of a metalloporphyrin with a 2-aminophenol axial ligand species. The central metal is hexacoordinated by the four nitrogen atoms of the pyrrole rings and the nitrogen atoms of the two Hon trans axial ligands.
基金supported by the National Natural Science Foundations of China (10972020,11061130550)Fundamental Research Funds for the Central UniversitiesNational Agency for Research of France (International project T-shock)
文摘The formation strength plateau of ceramics is addressed. A set of of 99A1203 are conducted, mechanism of the residual subjected to thermal shock thermal shock experiments where the thin specimens of 1 mm× 10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of ther- mal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.
文摘Recent studies have demonstrated a new role for Klf10, a Krüppel-like transcription factor, in skeletal muscle, specifically relating to mitochondrial function. Thus, it was of interest to analyze additional tissues that are highly reliant on optimal mitochondrial function such as the cerebellum and to decipher the role of Klf10 in the functional and structural properties of this brain region. In vivo (magnetic resonance imaging and localized spectroscopy, behavior analysis) and in vitro (histology, spectroscopy analysis, enzymatic activity) techniques were applied to comprehensively assess the cerebellum of wild type (WT) and Klf10 knockout (KO) mice. Histology analysis and assessment of locomotion revealed no significant difference in Klf10 KO mice. Diffusion and texture results obtained using MRI revealed structural changes in KO mice characterized as defects in the organization of axons. These modifications may be explained by differences in the levels of specific metabolites (myo-inositol, lactate) within the KO cerebellum. Loss of Klf10 expression also led to changes in mitochondrial activity as reflected by a significant increase in the activity of citrate synthase, complexes I and IV. In summary, this study has provided evidence that Klf10 plays an important role in energy production and mitochondrial function in the cerebellum.
文摘Both the primed in situ(PRINS)and the peptide nucleic acid-fluorescence in situ hybridization(PNA-FISH) techniques constitute alternatives to the conventional(fluorescence in situ hybridization,FISH)procedure for chro- mosomal investigations.The PRINS reaction is based on the use of a DNA polymerase and labeled nucleotide in an in situ primer extension reaction.Peptide nucleic acid probes are synthetic DNA analogs with uncharged polyamide backbones.The two procedures present several advantages(specificity,rapidity and discriminating ability)that make them very attractive for cytogenetic purposes.Their adaptation to human spermatozoa has allowed the development of new and fast procedures for the chromosomal screening of male gametes and has provided efficient complements to FISH for in situ assessment of aneuploidy in male gametes.(Asian J Androl 2006 Jul;8:387-392)
基金supported in part by SNF Strategic Japanese-Swiss Science and Technology Program(IZLJZ2_183660,YY)JSPS,under the Joint Research Program implemented in association with SNF(20191508,H.M.and N.Y.-S),SNF Project Funding(205321_173018,Y.Y.)+4 种基金ETH Research Grants(ETH-21_15-2ETH-36_20-2,Y.Y.)JSPS KAKENHI(Grant-in-Aid for Scientific Research[A],6251004,H.M.Grants-in-Aid for Scientific Research on Innovative Areas,21H00264,22H04707,H.M.Grant-in-Aid for Scientific Research[C],15K07164,N.Y.-S).
文摘Three water-soluble Mn(III)-porphyrin complexes with cationic pyridyl side groups bearing COOH-or OH-terminated carbon chains in the meta or para positions have been synthesized as probes for both magnetic resonance imaging(MRI)and photodynamic therapy(PDT).The complexes Mn-1,Mn-2,and Mn-3 are highly water-soluble,and their relaxivities range between 10 and 15 mM^(-1) s^(-1),at 20-80 MHz and 298 K,2-3 times higher than that of commercial Gd(III)-based agents.The complexes containing carboxylate(Mn-2)or alcoholic(Mn-3)side chains in the para position are endowed with higher relaxivities and have also shown efficient photoinduced DNA cleavage and singlet oxygen(^(1)O_(2))generation.Mn-3 with stronger photoinduced DNA cleavage has also revealed stabilizing and binding activities for G4 DNA,at a similar level as the known G4 binder Mn-TMPyP4.Nevertheless,the G4-binding activity of Mn-3 was nonspecific.Preliminary tests evidenced photocytotoxicity of Mn-3 on HeLa cells without a significant effect in the absence of light.Altogether,these results underline the potential of such water-soluble Mn(III)-porphyrins for the development of multimodal approaches combining MRI and PDT.
基金financially supported by the National Natural Science Foundation of China(No.U21A2050)support of the Chinese Scholarship Council(No.202006290165).
文摘In recent years,(0001)twist grain boundaries(BTGBs)located in primary α grain clusters were identified as fatigue crack nucleation sites in different Ti alloys.In the present study,crack initiation was investigated in a bimodal Ti-5Al-4 V alloy subjected to low-cycle fatigue and dwell-fatigue loadings at room temperature.The low fraction of primary α grains was not associated with a lack of sensitivity to BTGB cracking.Transmission electron microscopy and electron back-scattered diffraction were used to characterize BTGBs in the initial microstructure.The fatigue mechanisms were then analyzed with a focus on dislocation activity.α_(p) grains adjacent to cracked BTGBs contained a high dislocation density.It was primarily composed of planar slip bands of <a> dislocations.In addition,<c+a>dislocations were noticed in the vicinity of cracked BTGBs.They supposedly pertain to crack tip plasticity during growth,and no evidence of a role of an incoming slip event in crack nucleation was obtained.Also,basal slip bands extending across adjacent grains were found to emerge from BTGBs.This feature provides an easier path for crack extension when growth along the grain boundary becomes difficult owing to a deviation from the basal plane.Atom probe tomography analyses evidenced V and Fe segregation at a grain boundary with a significant deviation from the BTGB configuration.This suggests a possible contribution of local solute segregation to the high cracking resistance of general α_(p)/α_(p) grain boundaries.This work provides new insights into the mechanisms involved in cracking of BTGB in Ti alloys subjected to cyclic loadings.
基金supported by the French National Research Agency(ANR)in the framework of its“Jeunes chercheuses et jeunes chercheurs”program,ANR-21-CE09-0006.
文摘Despite numerous efforts from numerical approaches to complement experimental measurements,several fundamental challenges have still hindered one’s ability to truly provide an atomistic picture of the nucleation process in nanocrystals.Among them,our study resolves three obstacles:(1)Machinelearning force fields including long-range interactions able to capture the finesse of the underlying atomic interactions,(2)Data-driven characterization of the local ordering in a complex structural landscape associated with several crystal polymorphs and(3)Comparing results from a large range of temperatures using both brute-force and rare-event sampling.Altogether,our simulation strategy has allowed us to study zinc oxide crystallization from nano-droplet melt.Remarkably,our results show that different nucleation pathways compete depending on the investigated degree of supercooling.
