Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have ...Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have largely hampered their applications in these areas.This study outlines the fabrication of hybrid CNF@MOF aerogels by a stepwise assembly approach involving the coating and cross-linking of cellulose nanofibers(CNFs)with continuous nanolayers of MOFs.The cross-linking gives the aerogels high mechanical strength but superelasticity(80%maximum recoverable strain,high specific compression modulus of^200 MPa cm3 g−1,and specific stress of^100 MPa cm3 g−1).The resultant lightweight aerogels have a cellular network structure and hierarchical porosity,which render the aerogels with relatively low thermal conductivity of^40 mW m−1 K−1.The hydrophobic,thermally stable MOF nanolayers wrapped around the CNFs result in good moisture resistance and fire retardancy.This study demonstrates that MOFs can be used as efficient thermal insulation and flame-retardant materials.It presents a pathway for the design of thermally insulating,superelastic fire-retardant nanocomposites based on MOFs and nanocellulose.展开更多
Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfection strategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxyl radicals (&...Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfection strategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxyl radicals (&8226OH), superoxide radicals () and hydrogen peroxide (H2O2), generated in the photocatalytic reaction process are considered to be the active components prompting the bactericidal effect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidis and specific contributions of •OH, and H2O2 to the bactericidal process were studied using two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfaces and suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with a layer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficient ROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-step behavior with an initial region having a lower disinfection rate followed by a higher rate region after 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria and photocatalytic TiO2 nanoparticles, •OH and H2O2 showed equal significance in the bacterial inactivation having a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate. The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalytic disinfection that are essential for designing specific antibacterial applications of photocatalytic materials.展开更多
Upsalite®is a mesoporous magnesium carbonate synthesized without using surfactants and therefore highly attractive from environmental and production economy points of view. The material has recently been sugge...Upsalite®is a mesoporous magnesium carbonate synthesized without using surfactants and therefore highly attractive from environmental and production economy points of view. The material has recently been suggested as drug delivery vehicle and as topical bacteriostatic agent. In order to continue exploring these and other bio-related applications of the material, primary biocompatibility studies are needed. Herein we present the first in vivo acute systemic toxicity and skin irritation analyses as well as in vitro cytotoxicity evaluations of Upsalite®. The material was found to be non-toxic for human dermal fibroblasts cells up to a concentration of 1000 μg/ml and 48 h exposure in contrast to the mesoporous silica material SBA-15, used as reference, which significantly affected cell viability at particle concentration of 500 and 1000 μg/ml after the same exposure time. Topical application of Upsalite®resulted in negligible cutaneous reactions in a rabbit skin irritation model and no evidence of significant systemic toxicity was found when saline extracts of Upsalite®were injected in mice. Injection of sesame oil extract, however, resulted in transient weight loss, most likely due to injection of particles, and not toxic leachables. The presented results form the basis for future development of Upsalite®and similar mesoporous materials in biomedical applications and further toxicity as well as biocompatibility studies should be directed towards specific areas of use.展开更多
When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics (CFD) software provides high accuracy but with a very high computational cost, and in operational, mod...When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics (CFD) software provides high accuracy but with a very high computational cost, and in operational, moderate sea states, linear potential flow theories may be sufficient to model the hydrodynamics. In this paper, a model is built in COMSOL Multiphysics to solve for the hydrodynamic parameters of a point-absorbing wave energy device. The results are compared with a linear model where the hydrodynamical parameters are computed using WAMIT, and to experimental results from the Lysekil research site. The agreement with experimental data is good for both numerical models.展开更多
This work investigates the impact of biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapatite (HA) coated fixation pins during their insertion into synthetic bone. Stainless steel fixation ...This work investigates the impact of biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapatite (HA) coated fixation pins during their insertion into synthetic bone. Stainless steel fixation pins are coated with crystalline TiO2 by cathodic arc evaporation forming the bioactive layer for biomimetic deposition of Tobramycin containing HA. Tobramycin is either introduced by co-precipitation during HA formation or by adsorption-loading after HA deposition. The samples containing antibiotics are inserted into bone mimicking polyethylene foam after which the drug release is monitored using high performance liquid chromatography. This analysis shows that HA coating wear and delamination significantly decrease the amount of drug released during initial burst, but only marginally influence the sustained release period. Spalled coating fragments are found to remain within the synthetic bone material structure. The presence of HA within this structure supports the assumption that the local release of Tobramycin is not only expected to eliminate bacteria growth directly at the pin interface but as well at some distance from the implant. Furthermore, no negative effect of gamma sterilization could be observed on the drug release profile. Overall, the observed results demonstrate the feasibility of a multifunctional implant coating that is simultaneously able to locally deliver clinically relevant doses of antibiotics and an HA coating capable of promoting osteoconduction. This is a potentially promising step toward orthopaedic devices that combine good fixation with the ability to treat and prevent post-surgical infections.展开更多
Increasing interest in the role of ions such as calcium and strontium in bone formation has called for the investigation of multifunctional ion-doped implant coatings. Mesoporous titania coatings incorporating calcium...Increasing interest in the role of ions such as calcium and strontium in bone formation has called for the investigation of multifunctional ion-doped implant coatings. Mesoporous titania coatings incorporating calcium or strontium enabled a unique pore morphology and potential for drug delivery. Coatings were produced on titanium by an evaporation induced self-assembly method with the addition of calcium or strontium to the sol causing a shift in morphology from a hexagonally-packed to a worm-like porous network. Pore sizes ranged from 3.8 - 5 nm and coatings exhibited high surface areas between 181 - 215.5 m2/g, as measured by N2 adsorption-desorption. Coatings were loaded with 1 mg/ml Cephalothin, and showed sustained release of the antibiotic over one week in vitro. Cell studies confirmed that the ion addition had no toxic effect on human-like osteoblastic SaOS-2 cells. The results of this study suggest the potential for mesoporous coatings with calcium or strontium incorporation for direct bone-interfacing and combined drug delivery implant applications.展开更多
Herein, we show that incorporation of ions during biomimetic coating deposition may be utilized to tailor the drug loading capacity of hydroxyapatite (HA) coatings. Pure biomimetic HA (HA-B) and Si-doped equivalents (...Herein, we show that incorporation of ions during biomimetic coating deposition may be utilized to tailor the drug loading capacity of hydroxyapatite (HA) coatings. Pure biomimetic HA (HA-B) and Si-doped equivalents (SiHA-B) where deposited by a biomimetic process onto titanium dioxide covered titanium substrates. The antibiotic Cephalothin was incorporated into the coatings by adsorptive loading and the release was studied in-vitro. SiHA-B coatings exhibited superior drug incorporation capacity compared to pure HA-B coatings, resulting in a drug release profile dominated by an initial 10 min burst effect while a more prolonged 10 hour release was observed from HA-B coatings. The results emphasize the possibility to impact the drug release kinetics from implant coatings by selective doping elements and the use of thin, biomimetic HA-coatings as drug delivery vehicles. Functionalizing metal implants with SiHA-B coatings presents an interesting strategy towards creating synergetic effects through ion- and antibiotic release and, hence, contributing both towards preventing post-surgical infections while at the same time enhancing the bone-bonding ability.展开更多
The early fixation of bone screws after surgical implantation still remains a challenge in the field of traumatology. Whilst hydroxyapatite (HA) coatings are known to enhance the fixation of implants;their removal at ...The early fixation of bone screws after surgical implantation still remains a challenge in the field of traumatology. Whilst hydroxyapatite (HA) coatings are known to enhance the fixation of implants;their removal at a later time-point may be problematic. An HA coating has been developed to demonstrate that both implant fixation and safe removal are feasible in the same design. Accordingly the aim of this study was to compare the In-Vivo performance of thin biomimetic HA coated titanium screws to uncoated counterparts used as control after bilateral implantation in the femoral condyle of 36 New Zealand White Rabbits. The screws were analysed macroscopically, by histology, micro-CT and biomechanically at both two and six weeks post-implantation. The HA coated screws demonstrated excellent biocompatibility. At two weeks the HA coated screws demonstrated a significant increase in removal torque values as well as a strong trend towards higher pull-out forces. In addition histology confirmed a higher degree of osseointegration and direct bone to implant contact. At six weeks no difference in pull-out force and removal torque could be detected. SEM images confirmed the absence of any residual HA coating indicating a fast coating degradation In-Vivo. The low level of removal torque after full osseointegration at 6 weeks supports the feasibility of safe and easy removal of the implant. The HA coating under study appears to offer a unique characteristic of enhanced fixation with a minimal increase in removal torque after full osseointegration. This may be of value in clinical applications where it is necessary to assure both screw fixation and later removal.展开更多
Nanotopographical features are found to have significant effects on bone behavior. In the present study, nanoporous aluminas with different pore sizes (20, 100 and 200 nm in diameter), were evaluated for their osteoin...Nanotopographical features are found to have significant effects on bone behavior. In the present study, nanoporous aluminas with different pore sizes (20, 100 and 200 nm in diameter), were evaluated for their osteoinductive and drug eluting properties. W20-17 marrow stromal cells were seeded on nanoporous alumina with and without the addition of BMP-2. Although cell proliferation was not affected by pore size, osteogenic differentiation was 200 nm as compared to 20 and 100 nm pores induced higher alkaline phosphatase activity (ALP) and osteocalcin expression levels, thus indicating osteoblastic differentiation. Cell morphology revealed that cells cultured on 20 nm pores adopted a rounded shape, while larger pores (200 nm) elicited an elongated morphology. Furthermore, ALP expression levels were consistently higher on BMP-2 loaded nanoporous alumina surfaces compared to unloaded surfaces, indicating that not only is nanoporous alumina osteoinductive, but also has the potential to be used as a drug eluting bone-implant coating.展开更多
A series of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3)(0≤x≤0.08)crystals doped with different concentrations of Eu^(2+)were grown using the Bridgman-Stockbarger method.The work describes the influence of Eu^(2+)concentrat...A series of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3)(0≤x≤0.08)crystals doped with different concentrations of Eu^(2+)were grown using the Bridgman-Stockbarger method.The work describes the influence of Eu^(2+)concentration on the luminescent and kinetic properties of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3) crystals,as well as on their scintillation performance.The maximum in the radioluminescence spectra of these crystals shifts from 439 to446 nm with increasing europium concentration.The scintillation decay times of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3) lengthen with the Eu^(2+)content.The best light output of 33600photons/MeV is obtained for Cs_(0.2)Rb_(0.8)Ca_(0.93)Eu_(0.07)Br_(3),and the best energy resolution of 6.9%is found for Cs_(0.2)Rb_(0.8)Ca_(0.94)Eu_(0.06)Br_(3).展开更多
Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of...Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family,the structure and initial formation of the Ru^(Ⅲ)-bda aqua complex are still controversial.Herein,we challenge this often overlooked step by designing a pocketshape Ru-based complex 1.The computational studies showed that 1 possesses the crucial hydrophobicity at the Ru^(V)(O)state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts.Through characterization of single-crystal structures at the Ru^(Ⅱ) and Ru^(Ⅲ) states,a pseudo seven-coordinate“ready-togo”aqua ligand with Ru^(Ⅲ)…O distance of 3.62A was observed.This aqua ligand was also found to be part of a formed hydrogen-bonding network,providing a good indication of how the Ru^(Ⅲ)-OH_(2)complex is formed.展开更多
A new solar selective absorbing coating of Mo/NiAlN/NiAlON/SiO_2 multilayer was prepared on stainless steel(SS) substrates by magnetron sputtering for solar thermal power applications. The optical constants and thickn...A new solar selective absorbing coating of Mo/NiAlN/NiAlON/SiO_2 multilayer was prepared on stainless steel(SS) substrates by magnetron sputtering for solar thermal power applications. The optical constants and thickness of individual layers were simulated using the Scout software based on the experimentally measured reflectance and transmittance spectra of individual layers. The coating of Mo/NiAlN/NiAlON/SiO_2 with an ideal solar absorptance(α) of 0.945 in the solar spectrum range was designed via the optical constants of each layer in the Scout software. The Mo/NiAlN/NiAlON/SiO_2 coating was deposited via the optimized layer thickness. A good spectral selectivity with absorptance(α=0.936) and emittance(ε=0.09, T=80 ℃) was obtained. This method, which incorporates the optical simulation with the related experiments, provides a convenient approach to obtain the ideal solar selective absorbing coatings.展开更多
We report Pt deposition on a Si substrate by means of atomic layer deposition(ALD) using(methylcyclopentadienyl) trimethylplatinum(CH_3C_5H_4Pt(CH_3)_3) and O_2.Silicon substrates with both HF-last and oxidela...We report Pt deposition on a Si substrate by means of atomic layer deposition(ALD) using(methylcyclopentadienyl) trimethylplatinum(CH_3C_5H_4Pt(CH_3)_3) and O_2.Silicon substrates with both HF-last and oxidelast surface treatments are employed to investigate the influence of surface preparation on Pt-ALD.A significantly longer incubation time and less homogeneity are observed for Pt growth on the HF-last substrate compared to the oxide-last substrate.An interfacial oxide layer at the Pt-Si interface is found inevitable even with HF treatment of the Si substrate immediately prior to ALD processing.A plausible explanation to the observed difference of Pt-ALD is discussed.展开更多
Supramolecular self-assembly in water based on non-covalent bonding is attracting major attention due to the potential of hydrogels and aqueous polymers in biomedical applications.Although supramolecular polymerizatio...Supramolecular self-assembly in water based on non-covalent bonding is attracting major attention due to the potential of hydrogels and aqueous polymers in biomedical applications.Although supramolecular polymerization in organic solvents is well established,the key design features,the assembly mechanisms in water and achieving control over the aggregate structures remain challenging.Here,we present the assembly and disassembly of geometrical isomers of a stiff-stilbene bis-urea amphiphile(SA)in pure water.A remarkable feature of this system is that the(E)-isomer forms supramolecular polymers in both pure water and organic solvents.Taking advantage of this unique property,the hydrophobic effect was studied by comparing the supramolecular assembly in both systems.The assembly process inwater follows an enthalpy-driven nucleation-elongation(cooperative)supramolecular polymerization mechanism with a standard Gibbs free energy(ΔG°=−53 kJ mol^(−1))double the value of the one found in toluene.We attributed this distinctive feature to the hydrophobic effect in water.Furthermore,we discovered an isomer-dependent assembly process,which can be used to control aggregation in aqueous media.Due to the substantial geometric difference between(E)-SA and(Z)-SA,we compared their assembly in water to study the influence of different driving forces involved in the process.The supramolecular polymerization of(E)-SA was cooperatively influenced by hydrogen bonding,π-stacking,and hydrophobic effects,whereas the assembly of(Z)-SAwasmainly driven by hydrophobic effects.As a result,the fiber length of(E)-SA in water is much longer than that of(Z)-SA,presenting opportunities for geometrical control of aggregation in aqueousmedia.展开更多
文摘Metal–organic frameworks(MOFs)with high microporosity and relatively high thermal stability are potential thermal insulation and flame-retardant materials.However,the difficulties in processing and shaping MOFs have largely hampered their applications in these areas.This study outlines the fabrication of hybrid CNF@MOF aerogels by a stepwise assembly approach involving the coating and cross-linking of cellulose nanofibers(CNFs)with continuous nanolayers of MOFs.The cross-linking gives the aerogels high mechanical strength but superelasticity(80%maximum recoverable strain,high specific compression modulus of^200 MPa cm3 g−1,and specific stress of^100 MPa cm3 g−1).The resultant lightweight aerogels have a cellular network structure and hierarchical porosity,which render the aerogels with relatively low thermal conductivity of^40 mW m−1 K−1.The hydrophobic,thermally stable MOF nanolayers wrapped around the CNFs result in good moisture resistance and fire retardancy.This study demonstrates that MOFs can be used as efficient thermal insulation and flame-retardant materials.It presents a pathway for the design of thermally insulating,superelastic fire-retardant nanocomposites based on MOFs and nanocellulose.
基金The Carl Trygger Foundation,The Goran Gustafsson Foundation,The Swedish Research Council,Vinnova and The Swedish Foundation for Strategic Research for financially supporting this work
文摘Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfection strategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxyl radicals (&8226OH), superoxide radicals () and hydrogen peroxide (H2O2), generated in the photocatalytic reaction process are considered to be the active components prompting the bactericidal effect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidis and specific contributions of •OH, and H2O2 to the bactericidal process were studied using two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfaces and suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with a layer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficient ROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-step behavior with an initial region having a lower disinfection rate followed by a higher rate region after 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria and photocatalytic TiO2 nanoparticles, •OH and H2O2 showed equal significance in the bacterial inactivation having a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate. The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalytic disinfection that are essential for designing specific antibacterial applications of photocatalytic materials.
基金The Swedish Research Council and the Swedish Energy Agency are gratefully acknowledged for financial supportthe China Scholarship Council(CSC)for financial support.
文摘Upsalite®is a mesoporous magnesium carbonate synthesized without using surfactants and therefore highly attractive from environmental and production economy points of view. The material has recently been suggested as drug delivery vehicle and as topical bacteriostatic agent. In order to continue exploring these and other bio-related applications of the material, primary biocompatibility studies are needed. Herein we present the first in vivo acute systemic toxicity and skin irritation analyses as well as in vitro cytotoxicity evaluations of Upsalite®. The material was found to be non-toxic for human dermal fibroblasts cells up to a concentration of 1000 μg/ml and 48 h exposure in contrast to the mesoporous silica material SBA-15, used as reference, which significantly affected cell viability at particle concentration of 500 and 1000 μg/ml after the same exposure time. Topical application of Upsalite®resulted in negligible cutaneous reactions in a rabbit skin irritation model and no evidence of significant systemic toxicity was found when saline extracts of Upsalite®were injected in mice. Injection of sesame oil extract, however, resulted in transient weight loss, most likely due to injection of particles, and not toxic leachables. The presented results form the basis for future development of Upsalite®and similar mesoporous materials in biomedical applications and further toxicity as well as biocompatibility studies should be directed towards specific areas of use.
基金supported by the Center for Natural Disaster Science(CNDS)the Swedish Research Council(VR,Grant Number 2015-04657)+1 种基金Lars Hiertas FoundationBengt Ingestrms scholarship fund
文摘When designing a wave power plant, reliable and fast simulation tools are required. Computational fluid dynamics (CFD) software provides high accuracy but with a very high computational cost, and in operational, moderate sea states, linear potential flow theories may be sufficient to model the hydrodynamics. In this paper, a model is built in COMSOL Multiphysics to solve for the hydrodynamic parameters of a point-absorbing wave energy device. The results are compared with a linear model where the hydrodynamical parameters are computed using WAMIT, and to experimental results from the Lysekil research site. The agreement with experimental data is good for both numerical models.
文摘This work investigates the impact of biomechanical wear and abrasion on the antibiotic release profiles of hydroxyapatite (HA) coated fixation pins during their insertion into synthetic bone. Stainless steel fixation pins are coated with crystalline TiO2 by cathodic arc evaporation forming the bioactive layer for biomimetic deposition of Tobramycin containing HA. Tobramycin is either introduced by co-precipitation during HA formation or by adsorption-loading after HA deposition. The samples containing antibiotics are inserted into bone mimicking polyethylene foam after which the drug release is monitored using high performance liquid chromatography. This analysis shows that HA coating wear and delamination significantly decrease the amount of drug released during initial burst, but only marginally influence the sustained release period. Spalled coating fragments are found to remain within the synthetic bone material structure. The presence of HA within this structure supports the assumption that the local release of Tobramycin is not only expected to eliminate bacteria growth directly at the pin interface but as well at some distance from the implant. Furthermore, no negative effect of gamma sterilization could be observed on the drug release profile. Overall, the observed results demonstrate the feasibility of a multifunctional implant coating that is simultaneously able to locally deliver clinically relevant doses of antibiotics and an HA coating capable of promoting osteoconduction. This is a potentially promising step toward orthopaedic devices that combine good fixation with the ability to treat and prevent post-surgical infections.
基金supported by BIOMATCELL,VINN Excellence Center of Biomaterials and Cell Therapy,Gothenburg,Sweden and a VINNOVA VINNMER[grant 2010-01907]a STINT Institutional Grant for Younger Researchers.
文摘Increasing interest in the role of ions such as calcium and strontium in bone formation has called for the investigation of multifunctional ion-doped implant coatings. Mesoporous titania coatings incorporating calcium or strontium enabled a unique pore morphology and potential for drug delivery. Coatings were produced on titanium by an evaporation induced self-assembly method with the addition of calcium or strontium to the sol causing a shift in morphology from a hexagonally-packed to a worm-like porous network. Pore sizes ranged from 3.8 - 5 nm and coatings exhibited high surface areas between 181 - 215.5 m2/g, as measured by N2 adsorption-desorption. Coatings were loaded with 1 mg/ml Cephalothin, and showed sustained release of the antibiotic over one week in vitro. Cell studies confirmed that the ion addition had no toxic effect on human-like osteoblastic SaOS-2 cells. The results of this study suggest the potential for mesoporous coatings with calcium or strontium incorporation for direct bone-interfacing and combined drug delivery implant applications.
基金The Swedish Research Council,the Carl Trygger Foundation,the Goran Gustafsson Foundation,the Swedish Foundation for Strategic Research and Vinnova are acknowledged for financially supporting our research
文摘Herein, we show that incorporation of ions during biomimetic coating deposition may be utilized to tailor the drug loading capacity of hydroxyapatite (HA) coatings. Pure biomimetic HA (HA-B) and Si-doped equivalents (SiHA-B) where deposited by a biomimetic process onto titanium dioxide covered titanium substrates. The antibiotic Cephalothin was incorporated into the coatings by adsorptive loading and the release was studied in-vitro. SiHA-B coatings exhibited superior drug incorporation capacity compared to pure HA-B coatings, resulting in a drug release profile dominated by an initial 10 min burst effect while a more prolonged 10 hour release was observed from HA-B coatings. The results emphasize the possibility to impact the drug release kinetics from implant coatings by selective doping elements and the use of thin, biomimetic HA-coatings as drug delivery vehicles. Functionalizing metal implants with SiHA-B coatings presents an interesting strategy towards creating synergetic effects through ion- and antibiotic release and, hence, contributing both towards preventing post-surgical infections while at the same time enhancing the bone-bonding ability.
基金part of the 7^(th) Framework programme—BIODESIGN as well as the Swedish Science Council is gratefully acknowledged for financial support
文摘The early fixation of bone screws after surgical implantation still remains a challenge in the field of traumatology. Whilst hydroxyapatite (HA) coatings are known to enhance the fixation of implants;their removal at a later time-point may be problematic. An HA coating has been developed to demonstrate that both implant fixation and safe removal are feasible in the same design. Accordingly the aim of this study was to compare the In-Vivo performance of thin biomimetic HA coated titanium screws to uncoated counterparts used as control after bilateral implantation in the femoral condyle of 36 New Zealand White Rabbits. The screws were analysed macroscopically, by histology, micro-CT and biomechanically at both two and six weeks post-implantation. The HA coated screws demonstrated excellent biocompatibility. At two weeks the HA coated screws demonstrated a significant increase in removal torque values as well as a strong trend towards higher pull-out forces. In addition histology confirmed a higher degree of osseointegration and direct bone to implant contact. At six weeks no difference in pull-out force and removal torque could be detected. SEM images confirmed the absence of any residual HA coating indicating a fast coating degradation In-Vivo. The low level of removal torque after full osseointegration at 6 weeks supports the feasibility of safe and easy removal of the implant. The HA coating under study appears to offer a unique characteristic of enhanced fixation with a minimal increase in removal torque after full osseointegration. This may be of value in clinical applications where it is necessary to assure both screw fixation and later removal.
基金funded by Ollie och Elof Ericssons Stifelse for vetenskaplig forskning,Stiftelsen Lars Hiertas Minne and STINT(Stiftelsen for internationalisering av hogre utbildning och forskning).
文摘Nanotopographical features are found to have significant effects on bone behavior. In the present study, nanoporous aluminas with different pore sizes (20, 100 and 200 nm in diameter), were evaluated for their osteoinductive and drug eluting properties. W20-17 marrow stromal cells were seeded on nanoporous alumina with and without the addition of BMP-2. Although cell proliferation was not affected by pore size, osteogenic differentiation was 200 nm as compared to 20 and 100 nm pores induced higher alkaline phosphatase activity (ALP) and osteocalcin expression levels, thus indicating osteoblastic differentiation. Cell morphology revealed that cells cultured on 20 nm pores adopted a rounded shape, while larger pores (200 nm) elicited an elongated morphology. Furthermore, ALP expression levels were consistently higher on BMP-2 loaded nanoporous alumina surfaces compared to unloaded surfaces, indicating that not only is nanoporous alumina osteoinductive, but also has the potential to be used as a drug eluting bone-implant coating.
基金Project carried out in the frame of Crystal Clear Collaboration and supported by the National Academy of Sciences of Ukraine(0119U100764)。
文摘A series of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3)(0≤x≤0.08)crystals doped with different concentrations of Eu^(2+)were grown using the Bridgman-Stockbarger method.The work describes the influence of Eu^(2+)concentration on the luminescent and kinetic properties of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3) crystals,as well as on their scintillation performance.The maximum in the radioluminescence spectra of these crystals shifts from 439 to446 nm with increasing europium concentration.The scintillation decay times of Cs_(0.2)Rb_(0.8)Ca_(1-x)Eu_(x)Br_(3) lengthen with the Eu^(2+)content.The best light output of 33600photons/MeV is obtained for Cs_(0.2)Rb_(0.8)Ca_(0.93)Eu_(0.07)Br_(3),and the best energy resolution of 6.9%is found for Cs_(0.2)Rb_(0.8)Ca_(0.94)Eu_(0.06)Br_(3).
基金financially supported by the Swedish Research Council(2017-00935)the Knut and Alice Wallenberg Foundation(KAW 2016.0072)the China Scholarship Council(CSC).
文摘Isolation of RuⅢ-bda(17-electron specie)complex with an aqua ligand(2-electron donor)is challenging due to violation of the 18-electron rule.Although considerable efforts have been dedicated to mechanistic studies of water oxidation by the Ru-bda family,the structure and initial formation of the Ru^(Ⅲ)-bda aqua complex are still controversial.Herein,we challenge this often overlooked step by designing a pocketshape Ru-based complex 1.The computational studies showed that 1 possesses the crucial hydrophobicity at the Ru^(V)(O)state as well as similar probability of access of terminal O to solvent water molecules when compared with classic Ru-bda catalysts.Through characterization of single-crystal structures at the Ru^(Ⅱ) and Ru^(Ⅲ) states,a pseudo seven-coordinate“ready-togo”aqua ligand with Ru^(Ⅲ)…O distance of 3.62A was observed.This aqua ligand was also found to be part of a formed hydrogen-bonding network,providing a good indication of how the Ru^(Ⅲ)-OH_(2)complex is formed.
基金National Natural Science Foundation of China (No.51172012 and No.51472017)State Key Lab of Advance Metals and Materials (2014-ZD03)Foundation of Beijing Municipal Science & Technology Commission
文摘A new solar selective absorbing coating of Mo/NiAlN/NiAlON/SiO_2 multilayer was prepared on stainless steel(SS) substrates by magnetron sputtering for solar thermal power applications. The optical constants and thickness of individual layers were simulated using the Scout software based on the experimentally measured reflectance and transmittance spectra of individual layers. The coating of Mo/NiAlN/NiAlON/SiO_2 with an ideal solar absorptance(α) of 0.945 in the solar spectrum range was designed via the optical constants of each layer in the Scout software. The Mo/NiAlN/NiAlON/SiO_2 coating was deposited via the optimized layer thickness. A good spectral selectivity with absorptance(α=0.936) and emittance(ε=0.09, T=80 ℃) was obtained. This method, which incorporates the optical simulation with the related experiments, provides a convenient approach to obtain the ideal solar selective absorbing coatings.
基金Project supported by the National S&T Major Project 02(No.2009ZX02035-003)the National Natural Science Foundation of China(No. 61176090)the Program for Professor of Special Appointment(Eastern Scholar) at Shanghai Institutions of Higher Learning
文摘We report Pt deposition on a Si substrate by means of atomic layer deposition(ALD) using(methylcyclopentadienyl) trimethylplatinum(CH_3C_5H_4Pt(CH_3)_3) and O_2.Silicon substrates with both HF-last and oxidelast surface treatments are employed to investigate the influence of surface preparation on Pt-ALD.A significantly longer incubation time and less homogeneity are observed for Pt growth on the HF-last substrate compared to the oxide-last substrate.An interfacial oxide layer at the Pt-Si interface is found inevitable even with HF treatment of the Si substrate immediately prior to ALD processing.A plausible explanation to the observed difference of Pt-ALD is discussed.
基金financially supported by Shenzhen Science and Technology Project(CYJ20180507182246321 and JCYJ20200109105825504)Swedish Research Council VR(2016-06959)financial support from the Doctoral Joint-Training Program of China Scholarship Council.
基金supported by the National Natural Science Foundation of China(NSFC,22002123 and U1862111)Sichuan Science and Technology Program(2020YFH0118,2021JDGD0029 and 2021YFH0055)+6 种基金the Open Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201802)the Independent Research Fund Denmark-Nature Sciences(DFF-FNU,DFF-7014-00302)the Independent Research Fund Denmark-Sapere Aude starting grant(7026-00037A)the Research Fund for International Young Scientists from NSFC(21950410515)Swedish Research Council VR Starting Grant(2017-05337)the financial support from China Scholarship Council(201806320345,201908440313,201706170017,and 201806460021)Support from Swedish Energy Agency。
基金Financial support from the Netherlands Organization for Scientific Research(NWO-CW)the European Research Council(ERC,advanced grant no.694345 to B.L.F.)+2 种基金the Dutch Ministry of Education,Culture and Science(Gravitation program no.024.001.035)the China Scholarship Council(CSC,no.201707040064 to F.X.)the Marie Skłodowska-Curie Actions(Individual Fellowships no.838280 to S.C.and no.793082 to L.P.)is gratefully acknowledged.
文摘Supramolecular self-assembly in water based on non-covalent bonding is attracting major attention due to the potential of hydrogels and aqueous polymers in biomedical applications.Although supramolecular polymerization in organic solvents is well established,the key design features,the assembly mechanisms in water and achieving control over the aggregate structures remain challenging.Here,we present the assembly and disassembly of geometrical isomers of a stiff-stilbene bis-urea amphiphile(SA)in pure water.A remarkable feature of this system is that the(E)-isomer forms supramolecular polymers in both pure water and organic solvents.Taking advantage of this unique property,the hydrophobic effect was studied by comparing the supramolecular assembly in both systems.The assembly process inwater follows an enthalpy-driven nucleation-elongation(cooperative)supramolecular polymerization mechanism with a standard Gibbs free energy(ΔG°=−53 kJ mol^(−1))double the value of the one found in toluene.We attributed this distinctive feature to the hydrophobic effect in water.Furthermore,we discovered an isomer-dependent assembly process,which can be used to control aggregation in aqueous media.Due to the substantial geometric difference between(E)-SA and(Z)-SA,we compared their assembly in water to study the influence of different driving forces involved in the process.The supramolecular polymerization of(E)-SA was cooperatively influenced by hydrogen bonding,π-stacking,and hydrophobic effects,whereas the assembly of(Z)-SAwasmainly driven by hydrophobic effects.As a result,the fiber length of(E)-SA in water is much longer than that of(Z)-SA,presenting opportunities for geometrical control of aggregation in aqueousmedia.