The effect of laser surface melting on the corrosion resistance of AZ31 Mg alloy in 0.1 M NaCl solution was investigated using different laser processing conditions(energy densities of 14 and 17 J cm^(-2)).Laser treat...The effect of laser surface melting on the corrosion resistance of AZ31 Mg alloy in 0.1 M NaCl solution was investigated using different laser processing conditions(energy densities of 14 and 17 J cm^(-2)).Laser treatment induced rough surfaces primarily composed of oxidized species of Mg.XPS analysis revealed that the surface concentration of Al increased significantly as a consequence of LSM.Electrochemical impedance spectroscopy showed that the laser treatment remarkably increased the polarization resistance of the AZ31 Mg alloy and induced a passive-like region of about 100 mV,as determined by potentiodynamic polarization.Analysis of the results obtained provide solid evidence that within the immersion times used in this study,LSM treatment increased the corrosion resistance of AZ31 Mg alloy under open circuit conditions and anodic polarization.展开更多
Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much ...Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much simpler and cost effective.In this work,LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength.Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer.The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres.In first case,the oxygen pressure within the sputtering chamber was chosen to be high(3×10^–2 mbar)whereas it was one order of magnitude lower in second case(2.1×10^–3 mbar).In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films,respectively.The increase in photocatalytic activity is attributed to the enlargement of effective surface area.In comparative study,the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ^TM.展开更多
During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on...During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on the gas physical parameters, including the temperature, velocity and volume density of gas. It was found that, even in the case of optimized deposition parameters, the space distributions of gas parameters were heterogeneous due primarily to the thermal blockage come from the hot filaments and cryogenic pump effect arisen from the cold reactor wall. The distribution of volume density agreed well with the thermal round-flow phenomenon, one of the key obstacles to obtaining high growth rate in HFCVD process. In virtue of isothermal boundary with high temperature or adiabatic boundary condition of reactor wall, however, the thermal roundflow was profoundly reduced and as a consequence, the uniformity of gas physical parameters was considerably improved, as identified by the experimental films growth.展开更多
The characteristics of an innovative configuration of multiple radiofrequency(RF)coils immersed in a large metallic chamber are presented.Water-cooled copper coils were mounted within the slits of double-walled glass ...The characteristics of an innovative configuration of multiple radiofrequency(RF)coils immersed in a large metallic chamber are presented.Water-cooled copper coils were mounted within the slits of double-walled glass tubes,which were immersed into a stainless-steel chamber.The coils were connected in parallel to a gamma-type matching network,powered by an RF generator operating at industrial frequency.Adjustable leads enabled optimisation of the line impedances and thus uniformly distributed RF power across the four coils.Transitions from E-to H-mode and vice versa were measured for all coils at various oxygen pressures between 5 and 25 Pa.A uniform plasma was sustained in H-mode at the absorbed power threshold,which increased monotonously with increasing pressure in the metallic chamber.All coils exhibit the same E-to H-mode transition hysteresis and need the same amount of power for transitioning from E-to H-mode.The setup enables maintaining uniform plasma in virtually any number of coils at high power without the risk of arcing and without the dead volume typical for a classical configuration with coils mounted outside the metallic chamber.展开更多
Ion beam methods for modification of nanohardness of surface nanolayers of the titanium alloy Ti6AI4V were applied. After deposition of carbon nanolayers by electron beam evaporation, the ion implantation of nitrogen ...Ion beam methods for modification of nanohardness of surface nanolayers of the titanium alloy Ti6AI4V were applied. After deposition of carbon nanolayers by electron beam evaporation, the ion implantation of nitrogen into samples was carried out. The chemical composition of the modified surface area was investigated by AES （auger electron spectroscopy）. The nanohardness of resulted ion beam modified surface nanolayers were investigated by nanoindentation testing. The measured concentration profiles indicate the atomic mixing of carbon into the substrate. It was found that the modified samples had a markedly higher nanohardness than the unmodified samples. The increased nanohardness is attributed to the newly created phases in the surface area.展开更多
In this work,we evaluated the effect of the counter-body material(the same or dissimilar)and contact configuration(moving or stationary body),at similar contact tribological conditions,on the tribochemical and nanotop...In this work,we evaluated the effect of the counter-body material(the same or dissimilar)and contact configuration(moving or stationary body),at similar contact tribological conditions,on the tribochemical and nanotopography characteristics of adsorbed surface films.Zinc dialkyldithiophosphate(ZDDP),the best performing anti-wear additive,was used in self-mated steel/steel and DLC/DLC contacts,which were compared with mixed steel/DLC and DLC/steel contacts in 1-h and 6-h sliding tests.The macroscale(tribometer)and nanoscale(atomic force microscopy)friction,thickness,topography,and chemical(attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy)properties of the tribofilms were studied.The results revealed unexpectedly large differences in all the studied tribofilm parameters;this is because all the tribofilms are completely different;this includes the chemical composition,which is known to have a crucial effect on the nano-and macro-scale tribological properties.These results clearly demonstrate that the surface material,additives,and common contact operating parameters,that is,pressure,velocity,and temperature,crucially affect the ZDDP tribofilm as well as the position of the moving or stationary surface within the contact,and the material of the moving/stationary bodies.展开更多
Synchronous chemotherapy and radiotherapy,termed chemoradiation therapy,is now an important standard regime for synergistic cancer treatment.For such treatment,nanoparticles can serve as improved carriers of chemother...Synchronous chemotherapy and radiotherapy,termed chemoradiation therapy,is now an important standard regime for synergistic cancer treatment.For such treatment,nanoparticles can serve as improved carriers of chemotherapeutics into tumors and as better radiosensitizers for localized radiotherapy.Herein,we designed a Schottky-type theranostic heterostructure,Bi_(2)S_(3)-Au,with deep level defects(DLDs)in Bi_(2)S_(3) as a nano-radiosensitizer and CT imaging contrast agent which can generate reactive free radicals to initiate DNA damage within tumor cells under X-ray irradiation.Methotrexate(MTX)was conjugated onto the Bi_(2)S_(3)-Au nanoparticles as a chemotherapeutic agent showing enzymatic stimuli-responsive release behavior.The designed hybrid system also contained curcumin(CUR),which cannot only serve as a nutritional supplement for chemotherapy,but also can play an important role in the radioprotection of normal cells.Impressively,this combined one-dose chemoradiation therapeutic injection of co-drug loaded bimetallic multifunctional theranostic nanoparticles with a one-time clinical X-ray irradiation,completely eradicated tumors in mice after approximately 20 days after irradiation showing extremely effective anticancer efficacy which should be further studied for numerous anti-cancer applications.展开更多
The chloromethyl groups have been introduced into commercial S/DVB copolymer matrixes via interpenetratingpolymer networks (IPN) synthesis. The procedure involves impregnation of the Amberlite XAD-4 adsorbent,with use...The chloromethyl groups have been introduced into commercial S/DVB copolymer matrixes via interpenetratingpolymer networks (IPN) synthesis. The procedure involves impregnation of the Amberlite XAD-4 adsorbent,with use of the vinylbenzyl chloride (VBC) and divinylbenzene (DVB) monomers mixture, and suspensionpolymerization process. The syntheses were evaluated by FT-IR spectra and SEM analyses and furthermore bychlorine content determination as well as characterization of porous structure by nitrogen adsorption at liquid nitrogentemperature. Designed synthesis approach allowed determining organic and water phases composition. Furthermore,impact of an excess of the organic phase removal method has been investigated. Basing on the obtainedresults it could be stated that the chloromethyl groups, derived from VBC monomer, were successfully introducedinto the XAD-4 structure. Captured SEM images revealed significant changes in the beads’ surface morphology afterpolymerization processes. The presented studies reveal designed and executed synthesis processes, which involvethe use of a proper water phase and excess of organic phase removal. Observed changes in the beads’ morphologysuggest that introduced functionalities are concentrated on the porous surface of the XAD-4 adsorbent.展开更多
Fourier transform infrared spectroscopy(FTIR)is one of the most widely used vibrational diagnostic techniques to investigate gas-phase reactive oxygen and nitrogen species(RONS).However,the technique carries intrinsic...Fourier transform infrared spectroscopy(FTIR)is one of the most widely used vibrational diagnostic techniques to investigate gas-phase reactive oxygen and nitrogen species(RONS).However,the technique carries intrinsic challenges,particularly in relation to interfering peaks in the spectral data.This study explores the interfacial processes that occur when reactive oxygen and nitrogen species generated by a non-equilibrium air plasma interact with the metal halide windows of an FTIR gas cell,leading to the appearance and evolution of spurious absorption peaks which complicate spectral interpretation.Raman spectroscopy,X-ray photoelectron spectroscopy,time of flight secondary ion mass spectrometry and attenuated total reflectance-FTIR spectroscopy were used to elucidate the origin of spurious absorption peaks spanning the 1400-1300 cm^(-1)spectral range as a result of KBr exposure to plasma generated species.It was found that plasma exposed KBr contained a lower atomic fraction of Br which was replaced by the NO3nitrate group,the main absorbance peak of which progressively evolved with plasma exposure and affected the window transparency over the corresponding FTIR region.A correlation was revealed between KNO_(3)formation,plasma power and exposure time to a growth and change in molecular vibrational energies corresponding to asymmetric NO3stretching vibrations in the KNO_(3)structure.展开更多
基金the State Research Agency(Ministry of Science and Innovation of Spain),the Spanish National Research Council(CSIC)and the European Regional Development Fund(ERDF)for the support under the project RYC2019-027006-I(AEI/FEDER/UE)。
文摘The effect of laser surface melting on the corrosion resistance of AZ31 Mg alloy in 0.1 M NaCl solution was investigated using different laser processing conditions(energy densities of 14 and 17 J cm^(-2)).Laser treatment induced rough surfaces primarily composed of oxidized species of Mg.XPS analysis revealed that the surface concentration of Al increased significantly as a consequence of LSM.Electrochemical impedance spectroscopy showed that the laser treatment remarkably increased the polarization resistance of the AZ31 Mg alloy and induced a passive-like region of about 100 mV,as determined by potentiodynamic polarization.Analysis of the results obtained provide solid evidence that within the immersion times used in this study,LSM treatment increased the corrosion resistance of AZ31 Mg alloy under open circuit conditions and anodic polarization.
基金Deutsche Forschungsgemeinschaft (DFG), Germany (Grant number GR 1782/12)Science and Engineering Research Board (SERB), India (Grant number EMR/2015/001175)
文摘Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much simpler and cost effective.In this work,LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength.Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer.The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres.In first case,the oxygen pressure within the sputtering chamber was chosen to be high(3×10^–2 mbar)whereas it was one order of magnitude lower in second case(2.1×10^–3 mbar).In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films,respectively.The increase in photocatalytic activity is attributed to the enlargement of effective surface area.In comparative study,the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ^TM.
基金This work was partially supported by the National Natural Science Foundation of China （NSFC） under Contract No. 59292800 the Science and Technology Committee of Liaoning Province.
文摘During the growth of the hot filament chemical vapor deposition （HFCVD） diamond films, numerical simulations in a 2-D mathematical model were employed to investigate the influence of various deposition parameters on the gas physical parameters, including the temperature, velocity and volume density of gas. It was found that, even in the case of optimized deposition parameters, the space distributions of gas parameters were heterogeneous due primarily to the thermal blockage come from the hot filaments and cryogenic pump effect arisen from the cold reactor wall. The distribution of volume density agreed well with the thermal round-flow phenomenon, one of the key obstacles to obtaining high growth rate in HFCVD process. In virtue of isothermal boundary with high temperature or adiabatic boundary condition of reactor wall, however, the thermal roundflow was profoundly reduced and as a consequence, the uniformity of gas physical parameters was considerably improved, as identified by the experimental films growth.
基金funded by the Slovenian Research Agency,project No.L2-9235(Innovative configuration of inductively coupled gaseous plasma sources for up-scaling to industrialsize reactors)core funding P2-0082(thin-film structures and plasma surface engineering)。
文摘The characteristics of an innovative configuration of multiple radiofrequency(RF)coils immersed in a large metallic chamber are presented.Water-cooled copper coils were mounted within the slits of double-walled glass tubes,which were immersed into a stainless-steel chamber.The coils were connected in parallel to a gamma-type matching network,powered by an RF generator operating at industrial frequency.Adjustable leads enabled optimisation of the line impedances and thus uniformly distributed RF power across the four coils.Transitions from E-to H-mode and vice versa were measured for all coils at various oxygen pressures between 5 and 25 Pa.A uniform plasma was sustained in H-mode at the absorbed power threshold,which increased monotonously with increasing pressure in the metallic chamber.All coils exhibit the same E-to H-mode transition hysteresis and need the same amount of power for transitioning from E-to H-mode.The setup enables maintaining uniform plasma in virtually any number of coils at high power without the risk of arcing and without the dead volume typical for a classical configuration with coils mounted outside the metallic chamber.
文摘Ion beam methods for modification of nanohardness of surface nanolayers of the titanium alloy Ti6AI4V were applied. After deposition of carbon nanolayers by electron beam evaporation, the ion implantation of nitrogen into samples was carried out. The chemical composition of the modified surface area was investigated by AES （auger electron spectroscopy）. The nanohardness of resulted ion beam modified surface nanolayers were investigated by nanoindentation testing. The measured concentration profiles indicate the atomic mixing of carbon into the substrate. It was found that the modified samples had a markedly higher nanohardness than the unmodified samples. The increased nanohardness is attributed to the newly created phases in the surface area.
基金The authors acknowledge the financial support from the Slovenian Research Agency ARRS(research core funding No.P2-0231 Tribology and research project No.J2-7115 Nanoscale engineering of the contact interfaces for green lubrication technology).The authors also acknowledge F.Meunier from Oerlikon Balzers for providing the DLC coatings used in this work.
文摘In this work,we evaluated the effect of the counter-body material(the same or dissimilar)and contact configuration(moving or stationary body),at similar contact tribological conditions,on the tribochemical and nanotopography characteristics of adsorbed surface films.Zinc dialkyldithiophosphate(ZDDP),the best performing anti-wear additive,was used in self-mated steel/steel and DLC/DLC contacts,which were compared with mixed steel/DLC and DLC/steel contacts in 1-h and 6-h sliding tests.The macroscale(tribometer)and nanoscale(atomic force microscopy)friction,thickness,topography,and chemical(attenuated total reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy)properties of the tribofilms were studied.The results revealed unexpectedly large differences in all the studied tribofilm parameters;this is because all the tribofilms are completely different;this includes the chemical composition,which is known to have a crucial effect on the nano-and macro-scale tribological properties.These results clearly demonstrate that the surface material,additives,and common contact operating parameters,that is,pressure,velocity,and temperature,crucially affect the ZDDP tribofilm as well as the position of the moving or stationary surface within the contact,and the material of the moving/stationary bodies.
基金This work was supported by the Deputy of Research of Zanjan University of Medical Sciences(grant no.A-12-430-42,ethical code:IR.ZUMS.REC.1399.129)MB acknowledges the financial support of the Scientific and Technological Research Council of Turkey for Material Characterization(TUBITAK,217Z069).
文摘Synchronous chemotherapy and radiotherapy,termed chemoradiation therapy,is now an important standard regime for synergistic cancer treatment.For such treatment,nanoparticles can serve as improved carriers of chemotherapeutics into tumors and as better radiosensitizers for localized radiotherapy.Herein,we designed a Schottky-type theranostic heterostructure,Bi_(2)S_(3)-Au,with deep level defects(DLDs)in Bi_(2)S_(3) as a nano-radiosensitizer and CT imaging contrast agent which can generate reactive free radicals to initiate DNA damage within tumor cells under X-ray irradiation.Methotrexate(MTX)was conjugated onto the Bi_(2)S_(3)-Au nanoparticles as a chemotherapeutic agent showing enzymatic stimuli-responsive release behavior.The designed hybrid system also contained curcumin(CUR),which cannot only serve as a nutritional supplement for chemotherapy,but also can play an important role in the radioprotection of normal cells.Impressively,this combined one-dose chemoradiation therapeutic injection of co-drug loaded bimetallic multifunctional theranostic nanoparticles with a one-time clinical X-ray irradiation,completely eradicated tumors in mice after approximately 20 days after irradiation showing extremely effective anticancer efficacy which should be further studied for numerous anti-cancer applications.
文摘The chloromethyl groups have been introduced into commercial S/DVB copolymer matrixes via interpenetratingpolymer networks (IPN) synthesis. The procedure involves impregnation of the Amberlite XAD-4 adsorbent,with use of the vinylbenzyl chloride (VBC) and divinylbenzene (DVB) monomers mixture, and suspensionpolymerization process. The syntheses were evaluated by FT-IR spectra and SEM analyses and furthermore bychlorine content determination as well as characterization of porous structure by nitrogen adsorption at liquid nitrogentemperature. Designed synthesis approach allowed determining organic and water phases composition. Furthermore,impact of an excess of the organic phase removal method has been investigated. Basing on the obtainedresults it could be stated that the chloromethyl groups, derived from VBC monomer, were successfully introducedinto the XAD-4 structure. Captured SEM images revealed significant changes in the beads’ surface morphology afterpolymerization processes. The presented studies reveal designed and executed synthesis processes, which involvethe use of a proper water phase and excess of organic phase removal. Observed changes in the beads’ morphologysuggest that introduced functionalities are concentrated on the porous surface of the XAD-4 adsorbent.
基金financial support from the Public Agency for Research Activity of the Republic of Slovenia(awards J2-4490,J2-4451 and L2-4481)the UK Engineering and Physical Sciences Research Council(EPSRC)(awards EP/S025790/1 and EP/N021347/1)NATO(award G5814)
文摘Fourier transform infrared spectroscopy(FTIR)is one of the most widely used vibrational diagnostic techniques to investigate gas-phase reactive oxygen and nitrogen species(RONS).However,the technique carries intrinsic challenges,particularly in relation to interfering peaks in the spectral data.This study explores the interfacial processes that occur when reactive oxygen and nitrogen species generated by a non-equilibrium air plasma interact with the metal halide windows of an FTIR gas cell,leading to the appearance and evolution of spurious absorption peaks which complicate spectral interpretation.Raman spectroscopy,X-ray photoelectron spectroscopy,time of flight secondary ion mass spectrometry and attenuated total reflectance-FTIR spectroscopy were used to elucidate the origin of spurious absorption peaks spanning the 1400-1300 cm^(-1)spectral range as a result of KBr exposure to plasma generated species.It was found that plasma exposed KBr contained a lower atomic fraction of Br which was replaced by the NO3nitrate group,the main absorbance peak of which progressively evolved with plasma exposure and affected the window transparency over the corresponding FTIR region.A correlation was revealed between KNO_(3)formation,plasma power and exposure time to a growth and change in molecular vibrational energies corresponding to asymmetric NO3stretching vibrations in the KNO_(3)structure.
