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Image texture features and details are extremely important in image super-resolution. Meanwhile, preserving image texture features and details with less running time is also a significant problem to be solved. This paper proposes an image super-resolution method based on polynomial exponential function and non-uniform rectangular partition to restore the image structure and the details of edges and textures. The algorithm performs least-squares fitting according to the image grayscale to divide the low-resolution image into several different rectangular regions. By substituting the coordinates into each regional polynomial exponential function, the approximated regional high-resolution sub-image can be obtained to form the final whole high-resolution image. The proposed method can better represent the image textures in complex regions and effectively preserve edge details and suppress artifacts. The experimental results demonstrate that the proposed method is significantly superior to the state-of-the-art methods in the terms of subjective vision, objective quantitative evaluation, and execution time. [ABSTRACT FROM AUTHOR]

The sliding electrical contact (SEC) between rails and armature is a focus in electromagnetic rail launchers. The extreme conditions, such as high current density, high temperature, and high contact pressure, influence SEC performance. In this article, the segmented rails were used to study the effects of launch mass on SEC. Two groups of experiments, armatures with and without launch mass, were carried out. The mass difference of rail parts was measured, the macro- and micromorphology of rails surface were observed, and the driving current and muzzle voltage were obtained. Three conclusions are obtained: 1) the mass difference of rail parts in shooting with launch mass is greater than that without launch mass, due to the high temperature of armature contact surfaces; 2) because of the electron migration, the mass difference of the cathode rail is larger than the anode rail; and 3) the contact resistance between rails and armature without launch mass is lower than that with launch mass, result from the large contact area. Moreover, the current density and the temperature of the armature and rails were calculated. Results show that the temperature of surface of armature with launch mass is higher than that without launch mass. In a word, based on the results from experiments and simulations, the launch mass improves the sliding electric contact performance. [ABSTRACT FROM AUTHOR]

The strong temperature dependence of the contribution of nitrogen to diamond growth enhancement by microwave plasma chemical vapor deposition (MPCVD) have been firstly reported and systematically studied. Generally, an enhanced hydrogen desorption from the growing surface induced by the incorporated nitrogen atoms in diamond sublayer has been successfully used to explain the weak temperature depended growth enhancement of diamond by nitrogen addition, but cannot be employed to explain the observed strong temperature dependence of nitrogen contribution to diamond growth enhancement observed in this work. This indicates a significant change of surface kinetics of diamond growth induced by nitrogen addition should be occurred around 700 °C where a maximum value achieved. At this relative low temperature, the growing surface sites should be almost fully covered with hydrogen atoms with relative low nitrogen incorporated in the diamond. The adsorbed nitrogen may then make a contribution to promote hydrogen desorption, which is believed to play a dominant role in affecting the contribution of nitrogen. Experimental and calculation results do show that both the nitrogen adsorbed on the growing surface and incorporated in the sublayer may have different contribution to the growth rate enhancement, resulting in strong and weak temperature dependence, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Armature ejecta, which erodes the insulator and reduces surface dielectric strength, has been considered as a threat to solid-armature launchers. Two series of experiments were carried out in a small caliber launcher (SCL) to investigate the sources of armature ejecta and degradation mechanisms of the insulator. In first series of experiment, the ejection of armature was imaged by a high-speed camera. The influence of linear current density on ejection was studied in second series of experiment. Mass difference of insulator samples was used to evaluate the output of armature ejecta. Insulation performance was judged from the surface flashover voltage. And the degradation mechanism resulted from armature ejecta was analyzed based on the process of surface flashover. Results show that the local breakdown at armature–rail interfaces is one of the sources of armature ejecta. The amount of ejecta on samples increased with linear current density. Average flashover voltages decreased when ejecta increased in Zone A (0–200 mm) and Zone B (200–600 mm). And there was little difference of average flashover voltages in Zone C (600–900 mm). The discharge channel of the post-shot sample was composed of arcs and ejecta. The distortion of the surface electric field and the shorten of creepage distance are degradation mechanisms of bore insulators in solid-armature launchers. [ABSTRACT FROM AUTHOR]

Muzzle arc is a general phenomenon when the armature leaves the muzzle, and it is also a reason for the complexity of intermediate ballistic of electromagnetic launchers. In this article, a 3-D model has been developed to investigate muzzle arc flow field in a smaller caliber launcher. The coupled interaction of electromagnetic, flow, and thermal fields is realized by the magnetohydrodynamic (MHD) theory in conjunction with a renormalization group (RNG) $k$ - $\varepsilon $ turbulence model. The arc boundary conditions, arc root radius, and time-dependent current density are reasonably set on the basis of the experimental data and physical process. Simulation results reveal the relationship between muzzle arc and muzzle voltage. The rising edge of muzzle voltage corresponds to the arc expansion stage. The falling edge corresponds to the muzzle breakdown stage. And the turning point from rising edge to falling edge is the moment of muzzle breakdown. The flat section corresponds to the arc extinguishing stage. The muzzle blowback is the consequence of the arc expansion which produces a compression wave moving toward the breech. The velocity of blowback flow decreases from 670 to 270 m/s during the arc expansion stage. Then, it increases to about 350 m/s and tends to be stable due to the muzzle breakdown. [ABSTRACT FROM AUTHOR]

The blowback caused by the separation of rail and armature at muzzle is an important factor for the degradation of bore insulator. A small caliber launcher was modified by the transparent material of polycarbonate for capturing the process of blowback in inner bore with a high-speed camera. Three groups of experiments with the same peak linear current density and various muzzle currents were carried out. Nesting insulator samples were used to reduce the measurement error in cutting samples after experiments. Insulation performance of postshot samples was conducted from surface morphology, surface flashover voltage, and partial surface conductivity. Results show that the effects of blowback are related to muzzle current. With the increases of muzzle current, the average flashover voltage of samples in the region of 300–600 mm (600–900 mm) decreases from 9.98 kV/cm (5.37 kV/cm) to 3.59 kV/cm (3.01 kV/cm). Moreover, the number of samples that the flashover voltage is less than 9 kV/cm (half value of the original samples) increases from 7 to 12, which indicates that the damage area caused by blowback is gradually expanding with the muzzle current. Correspondingly, the partial surface conductivity of samples in 300–900 mm region increases with muzzle current. The increase of surface conductivity should be the main reason for the sharply decrease of surface flashover voltage. [ABSTRACT FROM AUTHOR]

As an important part of pulsed high-current launcher, insulator takes the functions of electrical insulation and support. Surveys were conducted after multishot to analysis matrix damage and insulation performance of insulator based on a medium-caliber and high linear current density launcher. Mechanical damage of matrix is mainly related to local current. The most serious damage located at zone of flattop and initial decline stage. In addition, serious damage may be caused by sprayed molten aluminum rather than high-temperature plasma. Metal contamination is dominated by local current and contact condition of rail–armature. There are more metal deposits on surface of high current and high muzzle voltage zones, and corresponding flashover voltages decrease significantly. Considering the effect of different damage forms and the operation conditions, the main damage form is matrix ablation located at the contact position of rail–insulator rather than the degradation of electrical insulation. Moreover, the main damage form of bore insulators is different for variety of caliber and linear current density launchers. Insulation damage may be considered mainly in small-caliber and low linear current density launcher, while mechanical damage may be considered mainly in large-caliber launcher and high linear current density launcher. [ABSTRACT FROM AUTHOR]

Surface modification of polytetrafluoroethylene (PTFE) is performed by nitrogen ion implantation for improving the PTFE surface flashover voltage in vacuum. In this paper, nitrogen ions are produced by an electron cyclotron resonance ion source. The properties of the samples are investigated with X-ray photoelectron spectroscopy, electrometer, microhardness tester, surface potential measurement, and surface flashover system. The Stopping and Range of Ions in Matter software is used to simulate the ion implantation. Experimental results show that the surface flashover voltage of treated samples improves remarkably and increases with the injection energy. After ion implantation, the content of fluorine in the treated samples decreases, and the content of oxygen increases. The surface conductivity increases from $1.15\times 10^{{-15}}$ to 1.36 10−13 S/m, the surface potential decreases faster, and the trap density and energy increase with the implantation energy. The process of electron avalanche and the accumulation of surface charges have been suppressed, thus hindering the development of flashover and improving the surface flashover voltage. [ABSTRACT FROM AUTHOR]

Silicon vacancies in diamond, one of the most promising single photon sources, is difficult to be achieved in a controlled and reproducible way due to complicated doping behavior of silicon in diamond by microwave plasma CVD. In this work, the underneath mechanism of silicon vacancies formed by unintentional silicon (The silicon source is SiO 2 from the microwave plasma CVD quartz window) doping in diamond was investigated from the view of growing surface kinetics through a series of experiments. During deposition, the addition of N 2 to the CH 4 -H 2 reaction gas mixture is beneficial to the formation of silicon vacancies in diamond from unintentional silicon doping, and the addition of a minor amount of oxygen will enhance the plasma etching. The increased number of the dangling bonds is beneficial to the formation of silicon vacancies and nitrogen vacancies in diamond, while excessive oxygen will passivation the dangling bonds and thus inhibit the formation of vacancies. Finally, the vertical distributions of the surface topography, growth rate, intensity of photoluminescence of NV and SiV color centers doped in the diamond film, are measured with high spatial resolution on growth surface, which are also related to the plasma electron temperature and density. These findings are of importance for searching of optimal growth regimes of NV and SiV doped single crystals by microwave plasma CVD. • The addition of nitrogen to the growth gas is beneficial to the formation of SiV−. • A minor amount of oxygen promotes while excessive oxygen inhibits the formation of NV− and SiV−. • The growth and distribution of NV− and SiV− in diamonds are related to the plasma on the surface of the substrate. [ABSTRACT FROM AUTHOR]

Rapid urbanization has made road construction and maintenance imperative, but detecting road diseases has been time-consuming with limited accuracy. To overcome these challenges, we propose an efficient YOLOv7 road disease detection model. Our approach involves integrating MobilieNetV3 as the backbone feature extraction network to reduce the network's parameters and computational requirements. Additionally, we introduce the BRA attention module into the spatial pyramid pooling module to eliminate redundant information and enhance the network's feature representation capability. Moreover, we utilize the F-ReLU activation function in the backbone network, expanding the convolutional layers' receptive field range. To optimize the model's boundary loss, we employ the Wise-IoU loss function, which places more emphasis on the quality of ordinary samples and enhances the overall performance and generalization ability of the network. Experimental results demonstrate that our improved detection algorithm achieves a higher recall rate and mean average precision (mAP) on the public dataset (RDD) and the NJdata dataset in Nanjing's urban area. Specifically, compared to YOLOv7, our model increases the recall rate and mAP on RDD by 3.3% and 2.6%, respectively. On the NJdata dataset, our model improves the recall rate and mAP by 1.9% and 1.3%, respectively. Furthermore, our model reduces parameter and computational requirements by 30% and 22.5%, respectively, striking a balance between detection accuracy and speed. In conclusion, our road disease detection model presents an effective solution to address the challenges associated with road disease detection in urban areas. It offers improved accuracy, efficiency, and generalization capabilities compared to existing models. [ABSTRACT FROM AUTHOR]

A pH-responsive MOF@Levo/LBL coating is developed on titanium implant surface for effectively inhibiting bacteria and enhancing osseointegration in vivo. • The MOF@Levo/LBL coating is fabricated on titanium implants. • The coating displays pH-response, while then inducing alkaline microenvironment. • The surface coated titanium implants show strong antibacterial activity in vivo. • The fabricated biocompatible titanium implants enhance bone formation in vivo. Bone implant-associated infection is one of the major concerns in orthopedics, and may even result in implant failure. To this end, we developed a strategy for the fabrication of an antibacterial coating on titanium (Ti) implants with pH-response to combat bacteria-mediated acidification of the local microenvironment. It includes three steps: first, we synthesized levofloxacin (Levo)-loaded zeolitic imidazolate framework-8 (ZIF-8@Levo) nanoparticles; second, the nanoparticles were loaded onto the collagen-modified Ti substrates by the cathode electrophoresis deposition (EPD) method; third, gelatin (Gel) and chitosan (Chi) multilayers were spin-coated on the modified Ti substrates, since the chelating effect of Gel and Chi would reduce the hydrolysis of ZIF-8@Levo for a sustained release of Levo and Zn2+. The fabricated samples of MOF@Levo/LBL promoted in vitro adhesion, proliferation, and differentiation of osteoblasts. Moreover, the MOF@Levo/LBL samples exhibited strong antibacterial ability against Escherichia coli and Staphylococcus aureus through hydrolysis of ZIF-8 nanoparticles, thereby creating a marginally alkaline microenvironment. Furthermore, in vivo implantation in a femur-infected rat model revealed that MOF@Levo/LBL implants effectively inhibited bacterial adhesion, apart from significantly improving osseointegration of the Ti implants. The study provides a promising alternative for fabricating multifunctional Ti implants with strong antibacterial capacity and enhanced bone formation for potential orthopedic application. [ABSTRACT FROM AUTHOR]

Background: Diffusion tensor imaging (DTI) is an effective method to identify subtle changes to normal-appearing white matter (WM). Here we analyzed the DTI data with other examinations, including motor evoked potentials (MEPs), histopathological images, and behavioral results, to reflect the lesion development in different degrees of spinal cord injury (SCI) in acute and subacute stages.Method: Except for 2 Sprague -Dawley rats which died from the anesthesia accident, the rest 42 female rats were randomized into 3 groups: control group (n = 6), moderate group (n = 18), and severe group (n = 18). Moderate (a 50-g aneurysm clip with 0.4-mm thickness spacer) or severe (a 50-g aneurysm clip with no spacer) contusion SCI at T8 vertebrae was induced. Then the electrophysiological assessments via MEPs, behavioral deterioration via the Basso, Beattie, and Bresnaha (BBB) scores, DTI data, and histopathology examination were analyzed.Results: In this study, we found that the damage of WM myelin, MEPs amplitude, BBB scores and the decreases in the values of fractional anisotropy (FA) and axial diffusivity (AD) were more obvious in the severe injury group than those of the moderate group. Additionally, the FA and AD values could identify the extent of SCI in subacute and early acute SCI respectively, which was reflected in a robust correlations with MEPs and BBB scores. While the values of radial diffusivity (RD) showed no significant changes.Conclusions: Our data confirmed that DTI was a valuable in ex vivo imaging tool to identify damaged white matter tracts after graded SCI in rat, which may provide useful information for the early identification of the severity of SCI. [ABSTRACT FROM AUTHOR]

Insulators between conductive rails assume a leading role in electrical insulation and support fixation. Failure of insulating materials during continuous repetitive launches has been found in experiments, the performance changes of insulators will directly affect efficiency and lifetime in repetitive electromagnetic launcher system. Many factors may influence the insulating performance because of complicated working condition, such as strong pulse stress and high temperature. A multishot minor-caliber launcher was designed for the study of the insulating performance. The length of the launcher is 890 mm with a caliber size of 10~\text mm \times 10 mm. C-shaped aluminum alloy armatures and glass-reinforced polymer insulator G10 are used. The muzzle speed is above 2 km/s. After the multishot experiments, the surface topography and surface resistivity of the insulators were measured by megger and digital microscope. The experimental and testing results show that the surface resistivity of G10 reduces gradually with the increase of experiment times, also the surface resistivity of different locations changes. Some pits and cracks appear at individual locations on the G10 surface, the phenomena of resin wear and fiber exposed are observed. Metal deposition is also found on the insulator surface by different types at different positions. Surface flashover voltage is measured after ablation. [ABSTRACT FROM AUTHOR]

The injectable micro-nano hydrogel we developed can be administered into articular cavities using a minimally invasive puncture needle. It undergoes degradation facilitated by MMP13, leading to the controlled release of celecoxib. This property effectively mitigates the inflammatory response and precisely reverses the OA process. [Display omitted] • The significance of MMP13 in osteoarthritis precise interventions was discussed. • Adapting to inflammatory levels and MMP13 changes, the microsphere achieves a responsive release of celecoxib. • This controllable drug delivery system holds promise for precise therapeutic interventions in diverse degenerative diseases. Osteoarthritis (OA) is characterized by cartilage degradation, inflammatory responses, and osteophyte formation. Matrix metalloproteinase 13 (MMP13) is a hallmark of OA development, and increased MMP13 expression is closely associated with extracellular matrix degradation. MMP13 expression varies significantly at different stages of OA progression. While cyclooxygenase 2 (COX-2) inhibitors are commonly used to treat OA, their long-term systemic administration increases the risks of adverse effects. Therefore, with the aim of achieving localized and responsive delivery of the COX-2 inhibitor celecoxib, the current study investigated an innovative MMP13-responsive micro-nano hydrogel microsphere system. Celecoxib-loaded cationic liposomes are non-covalently attached within the microsphere, enabling controlled drug release for OA treatment. In an OA environment with elevated MMP13 expression, the system is degraded via the action of MMP13 substrate peptide (MMP13sp), facilitating accelerated release of drug-loaded liposomes to improve the inflammatory microenvironment and treat OA rapidly. Compared to a phosphate-buffered saline solution with hyaluronidase (HAase), the prepared hyaluronic acid methacrylate microspheres HAMA/MMP13sp/Lipo@celecoxib exhibited rapid degradation in a solution containing a physiological concentration of MMP13/HAase, demonstrating specific enzyme responsiveness for precise anti-inflammatory drug release. The MMP13-responsive hydrogel microsphere system achieves intelligent and controllable drug release in OA, effectively decelerating disease progression and promoting articular cartilage repair. [ABSTRACT FROM AUTHOR]

Background: Muscle denervation from trauma and motor neuron disease causes disabling morbidities. A limiting step in functional recovery is the regeneration of neuromuscular junctions (NMJs) for reinnervation. Stem cells have the potential to promote these regenerative processes, but current approaches have limited success, and the optimal types of stem cells remain to be determined. Neural crest stem cells (NCSCs), as the developmental precursors of the peripheral nervous system, are uniquely advantageous, but the role of NCSCs in neuromuscular regeneration is not clear. Furthermore, a cell delivery approach that can maintain NCSC survival upon transplantation is critical. Methods: We established a streamlined protocol to derive, isolate, and characterize functional p75+ NCSCs from human iPSCs without genome integration of reprogramming factors. To enhance survival rate upon delivery in vivo, NCSCs were centrifuged in microwell plates to form spheroids of desirable size by controlling suspension cell density. Human bone marrow mesenchymal stem cells (MSCs) were also studied for comparison. NCSC or MSC spheroids were injected into the gastrocnemius muscle with denervation injury, and the effects on NMJ formation and functional recovery were investigated. The spheroids were also co-cultured with engineered neuromuscular tissue to assess effects on NMJ formation in vitro. Results: NCSCs cultured in spheroids displayed enhanced secretion of soluble factors involved in neuromuscular regeneration. Intramuscular transplantation of spheroids enabled long-term survival and retention of NCSCs, in contrast to the transplantation of single-cell suspensions. Furthermore, NCSC spheroids significantly improved functional recovery after four weeks as shown by gait analysis, electrophysiology, and the rate of NMJ innervation. MSC spheroids, on the other hand, had insignificant effect. In vitro co-culture of NCSC or MSC spheroids with engineered myotubes and motor neurons further evidenced improved innervated NMJ formation with NCSC spheroids. Conclusions: We demonstrate that stem cell type is critical for neuromuscular regeneration and that NCSCs have a distinct advantage and therapeutic potential to promote reinnervation following peripheral nerve injury. Biophysical effects of spheroidal culture, in particular, enable long-term NCSC survival following in vivo delivery. Furthermore, synthetic neuromuscular tissue, or "tissues-on-a-chip," may offer a platform to evaluate stem cells for neuromuscular regeneration. [ABSTRACT FROM AUTHOR]

Change of biophysical factors in tissue microenvironment is an important step in a chronic disease development process. A mechanical and biochemical factor from cell living microniche can regulate cell epigenetic decoration and, therefore, further induce change of gene expression. In this review, we will emphasize the mechanism that biophysical microenvironment manipulates cell behavior including gene expression and protein decoration, through modifying histone amino acid residue modification. The influence given by different mechanical forces, including mechanical stretch, substrate surface stiffness, and shear stress, on cell fate and behavior during chronic disease development including tumorigenesis will also be teased out. Overall, the recent work summarized in this review culminates on the hypothesis that a mechanical factor stimulates the modification on histone which could facilitate disease detection and potential therapeutic target. [ABSTRACT FROM AUTHOR]

For reconstructive surgeons, critically skeletal damage represents a major challenge. Growing evidence indicate that bone repair is dynamically regulated by the mesenchymal stem cell (MSC)‐macrophage interaction. Mechanical strain plays a fundamental role in bone repair and regeneration by influencing MSCs differentiation. Recently, a few findings indicate that macrophages may be mechanically sensitive and their phenotype can be regulated, in part, by mechanical cues. However, how macrophages subjected mechanical stretch influence the osteogenic differentiation of MSCs remain unclear. Thus, the purpose of this study is to explore the effect of macrophages stimulated with mechanical stretch on MSCs osteogenesis. By using a coculture system, we discover that macrophages efficiently induce osteogenic differentiation of MSCs under specific stretch conditions. A synergy mechanism between M2 polarization and YAP/BMP2 axis are identified through molecular and genetic analyses. Macrophages are activated by cyclic stretch and polarized to M2 phenotype that produce anti‐inflammatory cytokines such as IL‐10 and TGF‐β to regulate the local inflammatory microenvironment. Furthermore, mechanical stretch induces YAP activation and nuclear translocation, subsequently regulates downstream BMP2 expression to facilitate MSCs osteogenesis. These findings not only advance our understanding of the complex influence among the mechanical strain, macrophage inflammatory response as well as the osteogenic differentiation of MSCs, but also reveal a control system from mechanical signals to chemical response then to cell behaviors during bone repair and regeneration. [ABSTRACT FROM AUTHOR]

Mg-Zn-Sn-based alloys are widely used in the industrial field because of their low-cost, high-strength and heat-resistant characteristics. However, their application in the biomedical field has been rarely reported. In the present study, biodegradable Mg-1Zn-1Sn and Mg-1Zn-1Sn-0.2Sr alloys were fabricated. Their microstructure, surface characteristics, mechanical properties and bio-corrosion properties were carried out using an optical microscope (OM), X-ray diffraction (XRD), electron microscopy (SEM), mechanical testing, electrochemical and immersion test. The cell viability and morphology were studied by cell counting kit-8 (CCK-8) assay, live/dead cell assay, confocal laser scanning microscopy (CLSM) and SEM. The osteogenic activity was systematically investigated by alkaline phosphatase (ALP) assay, Alizarin Red S (ARS) staining, immunofluorescence staining and quantitative real time-polymerase chain reaction (qRT-PCR). The results showed that a small amount of strontium (Sr) (0.2 wt.%) significantly enhanced the corrosion resistance of the Mg-1Zn-1Sn alloy by grain refinement and decreasing the corrosion current density. Meanwhile, the mechanical properties were also improved via the second phase strengthening. Both Mg-1Zn-1Sn and Mg-1Zn-1Sn-0.2Sr alloys showed excellent biocompatibility, significantly promoted cell proliferation, adhesion and spreading. Particularly, significant increases in ALP activity, ARS staining, type I collagen (COL-I) expression as well as the expressions of three osteogenesis-related genes (runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (Bglap)) were observed for the Mg-1Zn-1Sn-0.2Sr group. In summary, this study demonstrated that Mg-Zn-Sn-based alloy has great application potential in orthopedics and Sr is an ideal alloying element of Mg-Zn-Sn-based alloy, which optimizes its corrosion resistance, mechanical properties and osteoinductive activity. [ABSTRACT FROM AUTHOR]

Generally, an excess of PbI 2 is used in the perovskite precursor solution to increase the crystallinity of the perovskite. However, excessive PbI 2 will form PbI 2 clusters during the annealing process of the perovskite film, which will cause the decomposition of perovskite solar cells (PSCs) and affect the stability of the device. Here we use 4-Difluoromethyl-Benzylamine Hydrochloride (4F 2 M-BACl) to do interfacial doping of the perovskite film to passivate the defects on the surface of the perovskite film and disperse the PbI 2 clusters through the interaction with PbI 2. Under the passivation effect of 4F 2 M-BACl, the power conversion efficiency (PCE) of PSCs was increased from 18.51% to 21.51%, and the hysteresis indicator (HI) was lower. In addition, the hydrophobic functional group F and benzene ring of 4F 2 M-BACl and the dispersing effect of 4F 2 M-BACl on PbI 2 have significantly improved the stability of the device. Unencapsulated devices with 4F 2 M-BACl modification were able to maintain over 85% of the initial PCE after 170 h at 80% relative humidity (RH). • Using 4-difluoromethyl-benzylamine hydrochloride to disperse PbI 2 clusters on the surface of thin films. • 4-difluoromethyl-benzylamine hydrochloride for surface passivation to reduce surface defects. • Large organic cations provide stability. [ABSTRACT FROM AUTHOR]

Size dependence of glutathione capped CdTe quantum dots (GSH-CdTe QDs) on the sensitivity and selectivity in the fluorometric detection of ferrous (II) ions (Fe2+) has been systematically investigated. Smaller-size QDs show higher sensitivity in the detection of Fe2+, resulting in higher quenching efficiency and red shift of the fluorescence peak of QDs. Stern–Volmer plots indicate that the charge transfer model can be employed to account for the observed fluorescence quenching effect. Fe2+ is bound to the surface of QDs by GSH and excited electrons are transferred from QDs to Fe2+, which facilitates a nonradiative recombination process and a decrease in the PL efficiency. In addition, the results from time resolved photoluminescence and a confocal scanning fluorescence microscope have shown that smaller-size QDs have a faster decrease in the fluorescence lifetime compared with that of larger-size QDs with Fe2+ addition, suggesting that the fast charge transfer in smaller-size QDs should be responsible for the observed fluorescence quenching effect. This Letter provides a comprehensive understanding of the mechanism of the fluorescence for the CdTe QDs quenched by Fe2+. [ABSTRACT FROM AUTHOR]

Graphic abstract SnO 2 incorporated in the surface film enhanced the anti-corrosion performance of Mg-4Zn-xSn alloys by the addition of Sn, the smooth surface of which displayed a poor bacterial adhesion (S. aureus) and strengthened the antibacterial property of the released metallic antibacterial ions like Zn2+ and Sn2+/Sn4+. Highlights • Sn decreased hydrogen release and improved antibacterial effect of Mg-4Zn alloy. • Mg-4Zn-1.5Sn alloy exhibited the best antibacterial property. • Antibacterial effect caused by Zn2+ and Sn2+/Sn4+ overwhelmed that by alkalization. Abstract Hydrogen release behavior and antibacterial property of Mg-4Zn- x Sn alloys (x = 0, 1.0, 1.5 wt%) were investigated by immersion tests, colony counting method and antibacterial adhesion, respectively. Results show that Sn-contained Mg-4Zn alloys have lower hydrogen release and better antibacterial property to Staphylococcus aureus (S. aureus) than that of Mg-4Zn alloy, for Sn incorporated in the surface film. Zn2+ and Sn2+/Sn4+ ions degraded from the alloys are the main cause for the high antibacterial effect. It provides an effective way to design materials to solve current shortcomings of biodegradable Mg alloys. [ABSTRACT FROM AUTHOR]

A weak negative thermal quenching (NTQ) effect of nitrogen vacancy centers in nitrogen-doped diamond is investigated by low-temperature photoluminescence technology. Results show that a weak NTQ phenomenon of the NV− centers was observed in the range of 10–40 K. Aiming to explain the observed NTQ effect, three hypotheses are proposed to classify the underlying physical mechanism, including (a) electron transfer from nitrogen atom to NV centers, (b) electron transfer between NV0 and NV− centers, and (c) the shallow traps of charge carriers in diamond. What is more, with incorporating sulfur, sulfur-nitrogen complex defects are formed with an impurity level of 0.65 eV below the conduction band. The activation energies of nonradiative recombination of NV− centers were obviously decreased with doping sulfur, which maybe related to the substitutional nitrogen (deep donor) replaced by sulfur-nitrogen complex structure defect (relatively shallow donor). The presented work provides a comprehensive understanding on the physical mechanism of NTQ effect of nitrogen vacancy centers in diamond, which would provide guidance for application of NV centers, especially in low temperatures. • A weak negative thermal quenching (NTQ) effect of NV- centers was observed. And the physical mechanism is investigated. • Sulfur-nitrogen complex defects are formed and behave like donors (impurity level is ∼0.65 eV below the conduction band). • The presented work provides a comprehensive understanding on the physical mechanism of NTQ effect in diamond. [ABSTRACT FROM AUTHOR]

Osteoporosis is one of the most prevalent age-related diseases worldwide, of which vertebral fracture is by far the most common osteoporotic fracture. Reduced bone formation caused by senescence is a main cause for senile osteoporosis, however, how to improve the osteogenic differentiation of osteoporotic bone marrow mesenchymal stem cells (BMSCs) remains a challenge. This study aimed to investigate the autophagic level changes in osteoporotic BMSCs derived from human vertebral body, and then influence osteogenesis through the regulation of autophagy. We found that hBMSCs from osteoporotic patients displayed the senescence-associated phenotypes and significantly reduced autophagic level compared to those derived from healthy ones. Meanwhile, the osteogenic potential remarkably decreased in osteoporotic hBMSCs, suggesting an inherent relationship between autophagy and osteogenic differentiation. Furthermore, rapymycin (RAP) significantly improved osteogenic differentiation through autophagy activatoin. However, the osteogenesis of hBMSCs was reversed by the autophagy inhibitor 3-methyladenine (3-MA). To provide more solid evidence, the hBMSCs pretreated with osteogenesis induction medium in the presence of 3-MA or RAP were implanted into nude mice. In vivo analysis showed that RAP treatment induced larger ectopic bone mass and more osteoid tissues, however, this restored ability of osteogenic potential was significantly inhibited by 3-MA pretreatment. In conclusion, our study indicated the pivotal role of autophagy for the osteo-differentiation hBMSCs, and offered novel therapeutic target for osteoporosis treatment. [ABSTRACT FROM AUTHOR]

d -Form and l -form peptide nanofiber scaffolds can spontaneously form stable β-sheet secondary structures and nanofiber hydrogel scaffolds, and hold some promise in hemostasis and wound healing. We report here on the synthetic self-assembling peptide d -RADA16 and l -RADA16 are both found to produce stable β-sheet secondary structure and nanofiber hydrogel scaffolds based on circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM) and rheology analysis etc. d -RADA16 hydrogel and l -RADA16 hydrogel can enhance obvious bone repair in femoral condyle defects of the Sprague-Dawley (SD) rat model compared to PBS treatment. Based on micro-computed tomography (CT), it was revealed that d -RADA16 hydrogel and l -RADA16 hydrogel were capable to obtain the extensive bone healing. Histological evaluation also found that these two hydrogels facilitate the presence of more mature bone tissue within the femoral condyle defects. Additionally, d -RADA16 hydrogel showed some potential in storing and releasing basic-fibroblast growth factor (bFGF) which was able to further promote bone regeneration based on micro-CT analysis. These results indicate that d -form peptide nanofiber hydrogel have some special capacity for bone repair. [ABSTRACT FROM AUTHOR]

Abstract: Experimental efforts for understanding the mechanisms of electroacupuncture (EA) for opiate addiction are partially hampered by restraint stress. In unrestrained animals, it is difficult to perform EA stimulation at acupuncture points frequently selected on the four limbs. The present study was performed to evaluate the effect of EA at the acupuncture point Shen-Shu (BL.23) on morphine withdrawal signs and c-Fos expression of the amygdala in freely moving rats or restrained rats. We applied immunohistochemistry to detect c-Fos-positive nuclei. Corticosterone levels and behavioral responses were measured during EA stimulation. The needles were bilaterally inserted and fixed at BL.23, and 100-Hz electric stimulation was conducted 30 min before naloxone-precipitated withdrawal. In both freely moving rats and restrained rats, EA significantly reduced the signs of morphine withdrawal. Notably, EA stimulation in freely moving rats attenuated c-Fos expression in the central nucleus of the amygdala while EA in restrained animals increased this response. In addition, the restrained rats emitted greater levels of vocalization and facial expression than freely moving rats during EA stimulation. Corticosterone levels were also significantly higher in restrained animals after EA stimulation. The new EA paradigm demonstrated in the present study might help the analysis of certain physiological responses induced by EA that would otherwise have been hindered by restraint stress. [Copyright &y& Elsevier]

Bone plates have been applied to fix fractures for over a hundred years. Metal plates are the gold standard. However, an increasing number of clinical practices and animal experiments have shown that metal plates have had incidents of failure due to their rigid fixation and long‐term complications. Degradable composites present the advantages of a lower elastic modulus and absorbable properties but are unsuitable for load‐bearing applications. Nondegradable bone plates composed of a nanohydroxyapatite/polyamide 66/glass fiber (n‐HA/PA66/GF) composite are prepared, which have enough strength and a low elastic modulus for an internal fixation device. To better assess its function as a bone plate, animal experiments are conducted using a canine load‐bearing femur fracture model. The results show that the n‐HA/PA66/GF plate can fix fractures effectively. Gross observation, radiographic films, and histological analysis all show that the n‐HA/PA66/GF plate leads to a secondary (indirect) union with obvious callus formation, whereas the titanium plate leads to primary (direct) union due to rigid fixation. Furthermore, the histological results reveal that new bone grows at the interface and that the n‐HA/PA66/GF plate can integrate with native bone tissue. Consequently, the n‐HA/PA66/GF composite shows good potential as a bone plate to fix loading‐bearing bone fractures. [ABSTRACT FROM AUTHOR]