Dry sliding tribological behavior of Zr-based bulk metallic glass

The tribological behavior of a Zr-based bulk metallic glass（BMG） was investigated using pin-on-disk sliding measurements in two different environments,i.e.,air and argon,against an yttria-stabilized zirconia counterface.It was found that the wear of the Zr-based BMG was reduced by more than 45% due to the removal of oxygen from the test environment at two different loads,i.e.,16 N and 23 N.The wear pins were examined using X-ray diffractometry,differential scanning calorimetry,scanning electron microscopy and optical surface profilometry.A number of abrasive particles and grooves presented on the worn surface of the pin tested in air,while a relatively smooth worn surface was observed in the specimens tested in argon.The wear mechanism of the pin worn in air was dominated by abrasive wear compared with an adhesive wear controlled process in the tests performed in argon.

Observation and modelling of snow and sea ice mass balance and its sensitivity to atmospheric forcing during spring and summer 2007 in the Central Arctic

Snow depth and sea ice thickness were observed applying an ice mass balance buoy(IMB)in the drifting ice station Tara during the International Polar Year in 2007.Detailed in situ observations on meteorological variables and surface fluxes were taken during May to August.For this study,the operational analyses and short-term forecasts from two numerical weather prediction(NWP)models(ECMWF and HIRLAM)were extracted for the Tara drift trajectory.We compared the IMB,meteorological and surface flux observations against the NWP products,also applying a one-dimensional thermodynamic sea ice model(HIGHTSI)to calculate the snow and ice mass balance and its sensitivity to atmospheric forcing.The modelled snow depth time series,controlled by NWP-based precipitation,was in line with the observed one.HIGHTSI reproduced well the snowmelt onset,the progress of the melt,and the first date of snow-free conditions.HIGHTSI performed well also in the late August freezing season.Challenges remain to model the“false bottom”observed during the melting season.The evolution of the vertical temperature profiles in snow and ice was better simulated when the model was forced by in situ observations instead of NWP results.During the melting period,the nonlinear ice temperature profile was successfully modelled with both forcing options.During spring and the melting season,total sea ice mass balance was most sensitive to uncertainties in NWP results for the downward longwave radiation,followed by the downward shortwave radiation,air temperature,and wind speed.

Effects of Different Pretreatment Modes on the Enzymatic Digestibility of Corn Leaf and Corn Stalk

Corn leaf and corn stalk were pretreated with only hot water and 0.1% sulfuric acid at 160℃ or 200℃, respectively. For hot water pretreatment, the pH of corn stalk hydrolysate decreased more rapidly than that of corn leaf as the reaction time increased. On the contrary, the pH of corn leaf hydrolysate increased more than that of corn stalk with diluted acid addition. Increasing temperature enhanced the xylose dissolution rate and increased cellulose digestibility. Compared with hot water, 0.1% sulfuric acid addition improved the xylan removal and the enzymatic hydrolysis of both corn leaf and corn stalk residue. Much less xylan must be removed to achieve the same cellulose digestibility for the corn leaf as that for the corn stalk; 55% digestibility was obtained when only 32% xylan was removed from corn leaf, whereas corn stalk required removal of about 50% of the xylan to achieve the same di- gestibility. Overall, the descending order of enzymatic digestibility was: dilute acid hydrolysate of corn leaf > dilute acid hydrolysate of corn stalk > water-only hydrolysate of corn leaf > water-only hydrolysate of corn stalk. Finally, one separate pretreatment strategy was developed to transfer corn leaf and corn stalk to fermentable sugars for fur- ther bioenergy production.

MR-GUIDED PULSE OXIMETRY IMAGING OF BREAST IN VIVO

A near-infrared(NIR)tomography system with spectrally-encoded sources in two wavelength bands was built to quantify the temporal oxyhemoglobin and deoxyhemoglobin contrast in breast tissue at a 20 Hz bandwidth.The system was integrated into a 3T magnetic resonance(MR)imaging system through a customized breast coil interface for simultaneous optical and MRI acquisition.In this configuration,the MR images provide breast tissue structural information for NIR spectroscopy of adipose andfibro-glandular tissue in breast.Spectral characterization performance of the NIR system was verified through dynamic phantom experiments.Normal human subjects were imaged withfinger pulse oximeter(PO)plethysmogram synchronized to the NIR system to provide a frequency-locked reference.Both the raw data from the NIR system and the recovered absorption coefficients of the breast at two wavelengths showed the same frequency of about 1.3 Hz as the PO output.The frequency lock-in approach provided a practical platform for MR-localized recovery of small pulsatile variations of oxyhemoglobin and deoxyhemoglobin in the breast,which are related to the heartbeat and vascular resistance of the tissue.

Enhanced wear resistance,antibacterial performance,and biocompatibility using nanotubes containing nano-Ag and bioceramics in vitro

A good Ti-based joint implant should prevent stress shielding and achieve good bioactivity and anti-infection performance.To meet these requirements,the low-elastic-modulus alloy—Ti–35Nb–2Ta–3Zr—was used as the substrate,and functional coatings that contained bioceramics and Ag ions were prepared for coating on TiO_(2)nanotubes(diameter:(80±20)nm and(150±40)nm)using anodization,deposition,and spin-coating methods.The effects of the bioceramics(nano-β-tricalcium phosphate,microhydroxyapatite(micro-HA),and meso-CaSiO_(3))and Ag nanoparticles(size:(50±20)nm)on the antibacterial activity and the tribocorrosion,corrosion,and early in vitro osteogenic behaviors of the nanotubes were investigated.The tribocorrosion and corrosion results showed that the wear rate and corrosive rate were highly dependent on the features of the nanotube surface.Micro-HA showed great wear resistance with a wear rate of(1.26±0.06)×10^(−3)mm^(3)/(N·m)due to adhesive and abrasivewear.Meso-CaSiO_(3)showed enhanced cell adhesion,proliferation,and alkaline phosphatase activity.The coatings that contained nano-Ag exhibited good antibacterial activity with an antibacterial rate of≥89.5%against Escherichia coli.These findings indicate that hybrid coatings may have the potential to accelerate osteogenesis.

Enhanced corrosion resistance,antibacterial properties and osteogenesis by Cu ion optimized MgAl-layered double hydroxide on Mg alloy

Magnesium(Mg)and its alloys have similar densities and elastic moduli to natural bone,making them an excellent choice for orthopedic implants.However,Mg alloys are prone to electrochemical corrosion,which often leads to implant failure and hinders the further development of Mg alloys due to bacterial infection around the implant.This work aims to enhance the corrosion resistance of Mg alloys,and provide theoretical guidance for solving the problem that Mg-based orthopedic implants are susceptible to bacterial infection and,thus,implant failure.In order to solve the corrosion problem,the Mg alloy AZ91D was used as the substrate,and a compact and uniform MgAlCu-layered double hydroxide(Mg(Cu)-LDH)was prepared on its surface using a hydrothermal method.The Mg(Cu)-LDH provides a barrier between the AZ91D and corrosive liquid,which effectively protects the Mg substrate from being corroded.The Mg(Cu)-LDH shows great cell viability for MC3T3-E1 cells.The Cu2+and Mg2+in the coating also endow the Mg(Cu)-LDH/AZ91D with antibacterial properties,showing strong antibacterial effects on both E.coli and S.aureus with antibacterial rates over 85%.Finally,in vivo results indicated that a LDH-coated implant had no systemic effects on the hearts,livers,spleens,lungs or kidneys.It was shown that 4 weeks after surgery the ratio of bone volume to tissue volume(BV/TV)of the LDH implant was 24%,which was 1.7 times that observed for AZ91D.

微粒对多晶冰流变行为的影响——(Ⅱ)滞弹性行为

用反相直接加载的方法研究了微粒对多晶冰滞弹性的影响.结果表明:在较高频率时(1Hz和10-1Hz),滞弹性应变与应力峰值呈线性关系;在较低频率时(10-2Hz),其应力/应变偏离线性关系.微粒在高频时(1Hz)通过阻碍晶界滑移对晶界弛豫产生重要影响,增加了模量和降低了内耗.但微粒对低频时的位错弛豫没有明显的影响.通过滞弹性实验计算了非线性弛豫模型的两个重要参数,计算表明K值约为0.07Pa,α值约为0.54.

微粒对多晶冰及冰川流变行为的影响——(Ⅰ)基于位错的弛豫模型

为量化冰及冰川在流变过程中位错密度随流变应力的变化,发展了一个基于位错的非线性弛豫模型.模型的计算表明:在冰的指数蠕变阶段,滞弹性试验所形成的应力/应变滞后环的宽度与面积随流变应力的增加呈线性增加,位错密度随流变应力的增加呈平方增加;在冰的线性蠕变阶段,滞弹性试验所形成的应力/应变滞后环的宽度、面积和位错密度保持不变.

Enabling stable sodium metal cycling by sodiophilic interphase in a polymer electrolyte system

Enabling highly reversible sodium(Na) metal anodes in a polymer electrolyte(PE) system is critical for realizing next-generation batteries with lower cost,higher energy,and improved safety.However,the uneven Na deposition and high Na/PE interphase resistance lead to poor reversibility and short cycle life of Na metal anodes.To tackle these problems,here a variety of metal nanoparticles(M-np,M=Al,Sn,In or Au) are deposited onto copper(Cu) foils to synthesize binder-free M-np@Cu substrates for Na plating/stripping.Notably,the Au-np@Cu substrate provides abundant preferential nucleation/growth sites,decreasing Na nucleation barrier and thus promoting uniform Na deposition.Accordingly,stable Na metal anodes are achieved with high reversible capacities,long cycle life,and high usage of Na.With the Au-np@Cu/Na anode and PE,the full cell using a commercial bulk sulfur cathode exhibits a reversible capacity of>400 mAh g^(-1) with near-100% Coulombic efficiency over 200 cycles.

乳腺肿瘤新辅助化疗反应的断层漫散射频谱评价:肿瘤感兴趣区变化的病例研究

目的评价两种方法通过感兴趣区（ROI）分析总结的断层漫散射频谱（DOS）数据，鉴别进展期乳腺癌病人行新辅助治疗后完全反应和不完全反应，并估算这些方法对于未来大规模研究设计强力分析的标准差。材料和方法本研究经学术审核委员会通过，参试者符合HIPAA影像检查的要求，提供书面知情同意通知，并给与一定补偿。

Microstructural evolution,mechanical properties and corrosion mechanisms of additively manufactured biodegradable Zn-Cu alloys

Additively manufactured (AM) biodegradable zinc (Zn) alloys constitute an important branch of orthopedic implants because of their moderate degradation properties and bone-mimicking mechanical properties. In this paper, the microstructural evolution and corrosion mechanisms of zinc-copper (Zn-Cu) alloys prepared by the laser-powder-bed-fusion (L-PBF) additive manufacturing method were investigated. Alloying with Cu significantly increases the ultimate tensile strength (UTS) of unalloyed Zn, but the UTS and ductility of unalloyed Zn and Zn-2Cu decrease with increasing laser energy density. Unalloyed Zn has a dendritic microstructure, while Zn-2Cu alloy has a peritectic microstructure. The formation of round peritectic grains is due to the low-temperature gradient of unalloyed Zn during the AM. The Zn-2Cu samples exhibited higher corrosion rates, addressing the problem of slow degradation of unalloyed Zn. The grain size distribution influences the corrosion behavior of the material. It enhances the corrosion rates of materials with fine grains in a non-passivating environment. However, the 100% extracts of Zn-2Cu samples exhibited greater values of cellular activity compared to unalloyed Zn samples, thus confirming their better cytocompatibility. This work demonstrates the great potential to design and modulate biodegradable Zn alloys to fulfill clinical needs by using AM technology.

Erratum to “A gyroscope-based system for intraoperative measurement of tibia coronal plane alignment in total knee arthroplasty” [Med Nov Technol Dev, 13, 2022, 100112]

The publisher would like to include the Ethical approval and informed consent statement for this paper.This study did not involve human subjects or animal research,and was therefore not subject to institutional ethics approval and did not require informed consent.The single cadaveric specimen used in ex vivo evaluation was obtained from Science Care(https://www.sciencecare.com/)and was handled in accordance with applicable Science Care policy.

Kinetic liquid metal synthesis of flexible 2D conductive oxides for multimodal wearable sensing

Transparent conducting oxides(TCOs)are crucial for high-performance displays,solar cells,and wearable sensors.However,their high process temperatures and brittle nature have hindered their use in flexible electronics.In this paper,we overturn these limitations by harnessing Cabrera-Mott oxidation to fabricate large-area,two-dimensional(2D)transparent electrodes via liquid metal printing.Our robotic,vacuum-free process deposits ultrathin(2–10 nm)indium tin oxide(ITO)with exceptional flexibility,transparency(>95%)and conductivity(>1300 S/cm)by utilizing hypoeutectic In-Sn alloys to print at<140℃.Detailed characterization reveals the efficacy of Sn-doping and high crystallinity with large,platelike grains.The ultrathin nature enhances bending strain tolerance and scratch resistance,exceeding durability of PEDOT and offering low contact impedance to skin comparable to Ag/AgCl.We implement 2D ITO in synchronous,multimodal electrocardiography(ECG)and pulse plethysmography(PPG)measurements.This order-of-magnitude improvement to printedTCOscould enable wearable biometrics and display-integrated sensors.

A review of non-noble metal-based electrocatalysts for CO_(2)electroreduction

The excessive emission of CO_(2) has caused many environmental issues and is severely threatening the eco-system.CO_(2) electroreduction reaction(CO_(2) RR) that driven by sustainable power is an ideal route for realizing the net reduction of CO_(2) and carbon recycle.Developing efficient electrocatalysts with low cost and high performance is critical for the wide applications of CO_(2) RR electrolysis.Among the various explored CO_(2) RR catalysts,non-noble metal(NNM)-based nanomaterials have drawn increasing attentions due to the remarkable performance and low cost.In this mini-review,the recent advances of NNM-based CO_(2) RR catalysts are summarized,and the catalysts are classified based on their corresponding reduction products.The preparation strategies for engineering the electrocatalysts are introduced,and the relevant CO_(2) RR mechanisms are discussed in detail.Finally,the current challenges in CO_(2) RR research are presented,and some perspectives are proposed for the future development of CO_(2) RR technology.This mini-review introduces the recent advances and frontiers of NNM-based CO_(2) RR catalysts,which should shed light on the further exploration of efficient CO_(2) RR electrocatalysts.

Interfacial structure design of MXene-based nanomaterials for electrochemical energy storage and conversion

2D transition metal carbides,carbonitrides,and nitrides known as MXenes possess high electrical conductivity,large redox active surface area,rich surface chemistry,and tunable structures.Benefiting from these exceptional chemical and physical properties,the applications of MXenes for electrochemical energy storage and conversion have attracted increasing research interests around the world.Notably,the electrochemical performances of MXenes are directly dependent on their synthesis conditions,interfacial chemistries and structural configurations.In this review,we summarize the synthesis techniques of MXenes,as well as the recent advances in the interfacial structure design of MXene-based nanomaterials for electrochemical energy storage and conversion applications.Additionally,we provide an in-depth discussion on the relationship between interfacial structure and electrochemical performance from the perspectives of energy storage and electrocatalysis mechanisms.Finally,the challenges and insights for the future research of interfacial structure design of MXenes are outlined.

A comparative study on microstructure,nanomechanical and corrosion behaviors of AlCoCuFeNi high entropy alloys fabricated by selective laser melting and laser metal deposition

The present study investigated the microstructure,nanomechanics,and corrosion behavior of AlCoCuFeNi high entropy alloys fabricated by selective laser melting(SLM)and laser metal deposition(LMD).The microstructure of SLM-processed specimens was mainly composed of columnar-grained BCC matrix(^90μm in width)and Cu-rich twinned FCC phase.The columnar grains grew epitaxially along the building direction and exhibited a strong{001}texture.In comparison,a coarse columnar-grained BCC matrix(^150μm in width)with a stronger<001>texture,rod-like B2 precipitates,and large core-shell structured FCC phases were formed in the LMD-processed specimens due to the higher heat accumulation effect.Consequently,the LMD-processed specimens showed a lower hardness,wear resistance,and corrosion resistance,but higher creep resistance and reduced Young's modulus than the SLM-processed specimens.Hot cracks occurred in both types of specimens,which could not be completely suppressed due to Cu segregation.

Is tumor cell specificity distinct from tumor selectivity in vivo?A quantitative NIR molecular imaging analysis of nanoliposome targeting

The significance and ability for receptor targeted nanoliposomes(tNLs)to bind to their molecular targets in solid tumors in vivo has been questioned,particularly as the efficiency of their tumor accumulation and selectivity is not always predictive of their efficacy or molecular specificity.This study presents,for the first time,in situ near-infrared(NIR)molecular imaging-based quantitation of the in vivo specificity of tNLs for their target receptors,as opposed to tumor selectivity,which includes influences of enhanced tumor permeability and retention.Results show that neither tumor delivery nor selectivity(tumor-to-normal ratio)of cetuximab and IRDye conjugated tNLs correlate with epidermal growth factor receptor(EGFR)expression in U251,U87,and 9L tumors,and in fact underrepresent their imaging-derived molecular specificity by up to 94.2%.Conversely,their in vivo specificity,which we quantify as the concentration of tNL-reported tumor EGFR provided by NIR molecular imaging,correlates positively with EGFR expression levels in vitro and ex vivo(Pearson’s r=0.92 and 0.96,respectively).This study provides a unique opportunity to address the problematic disconnect between tNL synthesis and in vivo specificity.The findings encourage their continued adoption as platforms for precision medicine,and facilitates intelligent synthesis and patient customization in order to improve safety profiles and therapeutic outcomes.

Color Cherenkov imaging of clinical radiation therapy

Color vision is used throughout medicine to interpret the health and status of tissue.Ionizing radiation used in radiation therapy produces broadband white light inside tissue through the Cherenkov effect,and this light is attenuated by tissue features as it leaves the body.In this study,a novel time-gated three-channel camera was developed for the first time and was used to image color Cherenkov emission coming from patients during treatment.The spectral content was interpreted by comparison with imaging calibrated tissue phantoms.Color shades of Cherenkov emission in radiotherapy can be used to interpret tissue blood volume,oxygen saturation and major vessels within the body.

A soft,high-density neuroelectronic array

Techniques to study brain activities have evolved dramatically,yet tremendous challenges remain in acquiring high-throughput electrophysiological recordings minimally invasively.Here,we develop an integrated neuroelectronic array that is filamentary,highdensity and flexible.Specifically,with a design of single-transistor multiplexing and current sensing,the total 256 neuroelectrodes achieve only a 2.3×0.3mm^(2)area,unprecedentedly on a flexible substrate.A single-transistor multiplexing acquisition circuit further reduces noise from the electrodes,decreases the footprint of each pixel,and potentially increases the device’s lifetime.The filamentary neuroelectronic array also integrates with a rollable contact pad design,allowing the device to be injected through a syringe,enabling potential minimally invasive array delivery.Successful acute auditory experiments in rats validate the ability of the array to record neural signals with high tone decoding accuracy.Together,these results establish soft,high-density neuroelectronic arrays as promising devices for neuroscience research and clinical applications.

Is clinically measured knee range of motion after total knee arthroplasty‘good enough?’:A feasibility study using wearable inertial measurement units to compare knee range of motion captured during physical therapy versus at home

Total knee arthroplasty is highly successful,in part due to range of motion(RoM)recovery.This is typically estimated goniometrically/visually by physical therapists(PTs)in the clinic,which is imprecise.Accordingly,a validated inertial measurement unit(IMU)method for capturing knee RoM was deployed assessing postoperative RoM both in and outside of the clinical setting.The study's objectives were to evaluate the feasibility of continuously capturing knee RoM pre-/post-op via IMUs,dividing data into PT/non-PT portions of each day,and comparing PT/non-PT metrics.We hypothesized IMU-based clinical knee RoM would differ from IMU-based knee RoM captured outside clinical settings.10 patients(3 M,69±13 years)completed informed consent documents following ethics board approval.A validated IMU method captured long duration(8–12 h/day,~50 days)knee RoM pre-/post-op.Post-op metrics were subdivided(PT versus non-PT).Clinical RoM and patient reported outcome measures were also captured.Compliance and clinical disruption were evaluated.ANOVA compared post-op PT and non-PT means and change scores.Maximum flexion during PT was less than outside PT.PT stance/swing RoM and activity level were greater than outside PT.No temporal variable differences were found PT versus non-PT.IMU RoM measurements capture richer information than clinical measures.Maximum PT flexion was likely less than non-PT due to the exercises completed(i.e.high passive RoM vs.low RoM gait).PT gait flexion likely exceed non-PT because of‘white coat effects’wherein patients are closely monitored clinically.This implies data captured clinically represents optimum performance whereas data captured non-clinically represents realistic performance.