Wrapping Layer Research Articles

Surface modification of LiFePO4 cathode enabled by highly Li+ mobility wrapping layer towards high energy and power density

Surface-modified cathode materials have been developed to achieve high-performance lithium secondary batteries with higher capacity, rate capability, and longer cycle performance than bulk active materials. In this study, a new surface-modified active material was explored through a low-temperature in situ-solution wrapping method (LiFePO4@Li4SiO4 composite). In addition, high Li-ion and electronic conductivity materials with amorphous nanostructures, in which the bulk LiFePO4 nanoparticles were covered with a Li4SiO4 layer, were demonstrated. In lithium-ion batteries, the LiFePO4@Li4SiO4 composite demonstrated enhanced charge transfer kinetics, which lowered the interfacial resistance between electrode and electrolyte and resulted in enhanced electrochemical performance when compared to that of bulk LiFePO4. Furthermore, Li4SiO4 is introduced as a surface stabilizer and effective Li-ion conductor to avoid side reactions and prevent the dissolution of active materials into the electrolyte. The designed cathode delivers a high specific discharge capacity of 171.8 mAh g-1 at 0.1 C with 99.76 % capacity retention after 150 cycles and a high capacity of 121.2 mAh g-1 at 10 C. Moreover, Li-ion full batteries employing LiFePO4@Li4SiO4 and graphite displayed a high specific energy density of 416.078 Wh kg-1 at a power density of 69.34 W kg-1 at 5 C. In summary, this paper reports a new strategy based on low-temperature in situ solution phase wrapping materials for developing active materials for high energy-power density energy storage devices.

K-Rich Spinel Interface of Air-Stable Layered Oxide Cathodes for Potassium-Ion Batteries.

Potassium-containing transition metal layered oxides (KxTmO2), although possessing high energy density and suitable operating voltage, suffer from severe hygroscopic properties due to their two dimensional (2D)layered structure. Their air sensitivity compromises structural stability during prolonged air exposure, therefore increasing the cost. The common sense for designing air-stable layered cathode materials is to avoid contact with H2Omolecules. In this study, it is surprisingly found that P3-type KxTmO2 forms an ultra-thin, potassium-rich spinel phase wrapping layer after simply water immersion, remarkedly reduces the reaction activity of the material's surface with air. Combined with Density Function Theory (DFT) calculations, this spinel phase is found to be able to effectively withstand air deterioration and preserving the crystal structure. Consequently, the water-treated material, when exposed to air, can largely maintain its good electrochemical performance, with capacity retention up to 99.15% compared to the fresh samples. Such an in situ surface phase transformation mechanism is also corroborated in other KxTmO2, underscoring its effectiveness in enhancing the air stability of P3-type layered oxides for K+ storage.

Novel Phononic-Like Crystal Wave Barrier Structure for Vibration Isolation

As an efficient, environmentally friendly, and economical urban public transportation tool, the subway has significant advantages compared to other urban public transportation tools and plays an irreplaceable role in the urban rail transit system. While the subway brings many conveniences to people, its operation has also brought a series of problems to urban development and residents’ lives, especially the vibration and noise problems generated by the subway have become unavoidable and urgent problems to be solved. The traditional wave barriers have a certain effect on attenuating and suppressing the vibration generated by the subway, but it has shortcomings in terms of the width and quantity of elastic wave bandgap (BG), so its application in low-frequency vibration reduction and isolation of subway systems is greatly limited. In order to broaden the elastic BG width and quantity of the wave barrier, this paper designs a novel phononic-like crystal subway wave barrier (PLCSWB) for subway vibration isolation based on locally resonant theory. Firstly, the dispersion curves of the novel PLCSWB are calculated using the improved plane wave expansion method and finite element method (FEM), and compared with the dispersion curves of traditional phononic crystal (PC) wave barriers. Secondly, the frequency response function of the novel PLCSWB is calculated using FEM to evaluate its attenuation effect on vibration, and the energy distribution characteristics at its BG boundary are analyzed. Then, the main factors affecting the BG of the novel PLCSWB are analyzed, and a spring–mass system equivalent model of the novel PLCSWB is established to theoretically estimate its BG range. Finally, the vibration data of the tunnel wall monitored on site are used to analyze and verify the vibration isolation effect of the novel PLCSWB. The results show that the novel PLCSWB opens five low-frequency BGs in the 200[Formula: see text]Hz frequency band, which increased the total width of the opened BGs by 49% compared to traditional PC wave barriers. In the frequency range of the BG, the attenuation value of the novel PLCSWB to vibration is mostly above 30[Formula: see text]dB, and the energy distribution inside the structure is mainly concentrated in the primitive cell that controls the BG, indicating good attenuation and control effects on vibration. The main factors affecting the BG of the novel PLCSWB are the density of the scatterer material, the elastic modulus, and the thickness of the wrapping layer material. Moreover, during subway operation, the novel PLCSWB has a good attenuation effect on the vibration transmitted from the tunnel wall to the soil. Among them, the maximum vibration acceleration amplitude of the novel PLCSWB with nine rows is reduced by 47%, and the vibration isolation performance is remarkable. The relevant research results of this paper provide a novel approach and method for the study of subway vibration reduction and isolation, and can also provide specific references for the design and development of wave barriers.

Comprehensive analysis of band gap modulation of hexagonal fan blade and optimized ligament structure in the low-frequency range

This paper proposed a meta material model with low-frequency wide band gap and band gap tunability, optimized its structure as a multibranch chain structure, and analyzed the band gap relationship of above two models based on Brag's theorem and finite element method. Among them, the fan base structure has a band gap of 65.92 % within 20,000 Hz, and the band gap is optimized to low-frequency after the structure is optimized, and the band gap reaches 75.94 % within 10,000 Hz. The effects of the ligament width and the thickness of the center parcel layer on the band gap distribution of the structure are also discussed, and the wave transmission characteristics in the structure are explored by group and phase velocities to verify the acoustic performance of the structure. The results show that the smaller the ligament thickness is, the lower the first band gap opening frequency of the structure is; when the thickness of the central wrapping layer is increased, the structure develops the band gap at the center frequency of 3000 Hz to a lower frequency and generates an ultra-wide band gap at the center frequency of 6000 Hz. These findings can provide a new idea for low-frequency vibration isolation and noise reduction.

Surface-enhanced Raman scattering-fluorescence dual-mode probes for target imaging of tumors, organoids and cancerous cells

A dual-mode nanoprobe (DMNP) overcomes the limitations of single probes and offers superior performance by combining their advantages. Herein, we report a DMNP design that features a gold nanosphere core and two layers of silica wrapping. The gold core surface is coated with 4-mercaptobenzoic acid(4-MBA), which serves as a Raman reporter. After the initial silica encapsulation, fluorophores in the form of conjugated polymer nanoparticles (CPNs) are applied to the surface. Finally, the encapsulation process is completed by adding the second layer of silica. The probe has dual-mode capabilities, including surface-enhanced Raman scattering (SERS) with a Raman enhancement factor of 134.1, and metal-enhanced fluorescence (MEF) with a fluorescence enhancement factor of 1.42. When modified with glycoprotein-3 (GPC3) antibody, the DMNPs probe shows excellent performance in fluorescence and SERS imaging for HepG2 liver cancer cells. When DMNP is conjugated with the breast tumor-specific antibody CA153, the DMNPs-AbCA153 probe enables imaging and induces apoptosis of breast cancer cells. These probes can serve as a platform for visualizing the distribution of cancer cell surface markers by modifying antibodies to recognize the cell surface. They have also shown significant potential as probes for oncology diagnosis and treatment monitoring.

Experimental study on performance of reinforced concrete short columns repaired and strengthened with Basalt fiber ultra-high-performance concrete (BF-UHPC)

To explore the reinforcement effectiveness of basalt fiber UHPC repair materials on concrete structures, this study designed four types of wrapping materials for C40 concrete short columns (inner columns), and formed four types of composite short columns. Axial compression tests were conducted on these specimens to analyze the effects of wrapping material type, wrapping material thickness, and protective layer thickness on bearing capacity. Additionally, a model for axial compressive bearing capacity of short column specimens, based on the Mander model and relevant parameter modifications, was established. The results show that: (1) All designed short column specimens showed brittle failure in the experiment, and the brittle failure phenomenon during the experiment is like that of ordinary concrete short columns constrained by stirrups. (2) The type of wrapping material and the thickness of the wrapping layer are important factors affecting the axial compressive bearing capacity of the entire short column. (3) Adding an appropriate amount of basalt fiber and nano-silica significantly enhances the reinforcing and repairing capabilities of the repair material, thereby improving the load-bearing capacity of the repaired concrete columns. (4) Based on the Mander model and the correction of correlation coefficients, a model for axial compressive bearing capacity of short column specimens was established.

Visualization and Experimental Characterization of Wrapping Layer Using Planar Laser-Induced Fluorescence.

Droplets on nanotextured oil-impregnated surfaces have high mobility due to record-low contact angle hysteresis (∼1-3°), attributed to the absence of solid-liquid contact. Past studies have utilized the ultralow droplet adhesion on these surfaces to improve condensation, reduce hydrodynamic drag, and inhibit biofouling. Despite their promising utility, oil-impregnated surfaces are not fully embraced by industry because of the concern for lubricant depletion, the source of which has not been adequately studied. Here, we use planar laser-induced fluorescence (PLIF) to not only visualize the oil layer encapsulating the droplet (aka wrapping layer) but also measure its thickness since the wrapping layer contributes to lubricant depletion. Our PLIF visualization and experiments show that (a) due to the imbalance of interfacial forces at the three-phase contact line, silicone oil forms a wrapping layer on the outer surface of water droplets, (b) the thickness of the wrapping layer is nonuniform both in space and time, and (c) the time-average thickness of the wrapping layer is ∼50 ± 10 nm, a result that compares favorably with our scaling analysis (∼50 nm), which balances the curvature-induced capillary force with the intermolecular van der Waals forces. Our experiments show that, unlike silicone oil, mineral oil does not form a wrapping layer, an observation that can be exploited to mitigate oil depletion of nanotextured oil-impregnated surfaces. Besides advancing our mechanistic understanding of the wrapping oil layer dynamics, the insights gained from this work can be used to quantify the lubricant depletion rate by pendant droplets in dropwise condensation and water harvesting.

Effect of the Wrapping Layers Number and Length on the Flexural Properties of Chestnut Beams Reinforced with Basalt-FRP

Effect of the Wrapping Layers Number and Length on the Flexural Properties of Chestnut Beams Reinforced with Basalt-FRP

Augmentation of ACL Autograft Reconstruction With an Amnion Collagen Matrix Wrap and Bone Marrow Aspirate Concentrate: A Pilot Randomized Controlled Trial With 2-Year Follow-up.

It is theorized that the lack of a synovial lining after anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) contributes to slow ligamentization and possible graft failure. Whether graft maturation and incorporation can be improved with the use of a scaffold requires investigation. To evaluate the safety and efficacy of wrapping an ACL autograft with an amnion collagen matrix and injecting bone marrow aspirate concentrate (BMAC), quantify the cellular content of the BMAC samples, and assess 2-year postoperative patient-reported outcomes. Randomized controlled trial; Level of evidence, 2. A total of 40 patients aged 18 to 35 years who were scheduled to undergo ACLR were enrolled in a prospective single-blinded randomized controlled trial with 2 arms based on graft type: bone-patellar tendon-bone (BTB; n = 20) or hamstring (HS; n = 20). Participants in each arm were randomized into a control group who underwent standard ACLR or an intervention group who had their grafts wrapped with an amnion collagen matrix during graft preparation, after which BMAC was injected under the wrap layers after implantation. Postoperative magnetic resonance imaging (MRI) mapping/processing yielded mean T2* relaxation time and graft volume values at 3, 6, 9, and 12 months. Participants completed the Single Assessment Numeric Evaluation Score, Knee injury and Osteoarthritis Outcome Score, and pain visual analog scale. Statistical linear mixed-effects models were used to quantify the effects over time and the differences between the control and intervention groups. Adverse events were also recorded. No significant differences were found at any time point between the intervention and control groups for BTB T2* (95% CI, -1.89 to 0.63; P = .31), BTB graft volume (95% CI, -606 to 876.1; P = .71), HS T2* (95% CI, -2.17 to 0.39; P = .162), or HS graft volume (95% CI, -11,141.1 to 351.5; P = .28). No significant differences were observed between the intervention and control groups of either graft type on any patient-reported outcome measure. No adverse events were reported after a 2-year follow-up. In this pilot study, wrapping a graft with an amnion collagen matrix and injecting BMAC appeared safe. MRI T2* values and graft volume of the augmented ACL graft were not significantly different from that of controls, suggesting that the intervention did not result in improved graft maturation. NCT03294759 (ClinicalTrials.gov identifier).

Cost effective synthesis hetero-structured N-doped C-coated Ni9S8/Ni3S2/NiS1.03 nanoparticles attached on 3D reduced graphene oxide anode to exceptional Li-ion performance

In this study, nitrogen all-doped carbon-coated Ni9S8/Ni3S2/NiS1.03 (NixSy) particles with homogeneous bonds to 3D reduced graphene oxide sheets (N-NixSy@C/G) were synthesized via a using the facile hydrothermal, freeze-drying and subsequent calcination method. In this structure, the carbon layer derived from glucose was highly uniformly dispersed in an Ar atmosphere, such that the structural stability is enhanced and the volume expansion of NixSy is effectively mitigated. The Ni9S8, Ni3S2 and NiS1.03 nanoparticles were formed effectively facilitated under the existence of glucose. In situ nitrogen doping was achieved by the presence of urea containing nitrogen, such as electron conductivity was increased and fast ion intercalation was facilitated. The structural stability and cyclability can be ensured for the high flexibility and structural strength of the reduced graphene oxide wrapping layer. Under the synergistic effect exerted by the three modules, N-NixSy@C/G was further endowed with high electrical conductivity, large specific surface area as well as abundant electrochemical reaction sites. On that basis, the N-NixSy@C/G anode that was employed in the lithium-ion batteries exhibited superior rate capability and ultra-high reversible capacity (826.3 mAh g−1 at 0.5 A g−1). The capacity was kept at 703 mAh g−1 and the coulombic efficiency reached 100% after 1000 cycles at a current density of 2 A g−1. This study may contribute to the creation of a distinctive avenue for designing quick and high-capacity metal sulfide anodes and boost the growth of high-performance lithium batteries.

Low Frequency Attenuation Characteristics of Two-Dimensional Hollow Scatterer Locally Resonant Phonon Crystals.

The finite element method (FEM) was applied to study the low frequency band gap characteristics of a designed phonon crystal plate formed by embedding a hollow lead cylinder coated with silicone rubber into four epoxy resin short connecting plates. The energy band structure, transmission loss and displacement field were analyzed. Compared to the band gap characteristics of three traditional phonon crystal plates, namely, the square connecting plate adhesive structure, embedded structure and fine short connecting plate adhesive structure, the phonon crystal plate of the short connecting plate structure with a wrapping layer was more likely to generate low frequency broadband. The vibration mode of the displacement vector field was observed, and the mechanism of band gap formation was explained based on the spring mass model. By discussing the effects of the width of the connecting plate, the inner and outer radii and height of the scatterer on the first complete band gap, it indicated that the narrower the width of the connecting plate, the smaller the thickness; the smaller the inner radius of the scatterer, the larger the outer radius; and the higher the height, the more conducive it is to the expansion of the band gap.

High-efficiency recycling of copper-cadmium slag by ozonation with ultrasonic catalysis

Copper-cadmium slag, a kind of hazardous metallurgical solid waste, has attracted attention in the fields of environmental protection and resource recovery because of its high output and richness of valuable metals. However, it is difficult to separate and recycle efficiently due to its oxidation resistance and strong wrapping property. To address this challenge, the ozonation with ultrasonic catalysis method is proposed for leaching of copper-cadmium slag in this work. Mechanical and cavitation effects of ultrasound can break wrapping layer and renew reaction interfaces. The active free radicals produced by ultrasonic/ozone can enhance the oxidation of reaction system and cause the inert metal copper to oxidize more easily. The leaching percentage of copper is 99.3%, which is 45.7% higher than that of conventional condition. Diffusion is proved to be the restrictive link in the copper dissolution process via kinetic experiment with a low activation energy of 3.71 kJ/mol under ultrasonic/ozone condition. The hydroxyl radical is detected by electron paramagnetic resonance and confirmed that it is beneficial to increase the recovery rate of metal in slag by quenching experiment. This study illustrates the value of ozonation with ultrasonic catalysis technology in efficient and green economy separation and recovery of various metals from hazardous waste.

Effects of mineral admixture on properties of cement-based foam material developed for preventing coal spontaneous combustion

This study investigated the cement-based foam material (CBFM) used in mine fire-extinguishing materials by using a self-made compound foaming agent, water, cement, mineral admixture included fly ash (FA), blast furnace slag (BFS) and silica fume (SF), etc. The effects of mineral admixture type, dosage, foam content and water-binder ratio on the properties of CBFM were analyzed using the orthogonal tests, further determining the optimal ratio of CBFM. Moreover, the influence of mineral admixture type on the performance of the CBFM was analyzed by comparing the scanning electronic microscope and X-ray diffraction test. As a result, when the BFS content was 20%, the foam content was 2 times that of the cementitious slurry, and the water-binder ratio is 0.5, the overall performance of CBFM could be optimized. The surface morphology and mineral component investigation exhibited that CBFM with BFS as a mineral admixture had the more uniform closed-cell structure than FA and SF. Moreover, the novel material had the inhibitory effect on the transformation of calcium aluminate hydrate and hydrated calcium sulfoaluminate, which in turn could maintain the strength of the composite. The experimental results showed that the fire extinguishing and cooling effect of CBFM was better than that of traditional fly ash foam, and it could quickly cool down the temperature burning coal pile within 30 min. In addition, the solidification products of CBFM would form a wrapping layer on the surface of the loose coal pile, inhibiting the contact between coal and air, further preventing coal spontaneous combustion effectively.

Unique Device Identification–Based Linkage of Hierarchically Accessible Data Domains in Prospective Surgical Hospital Data Ecosystems: User-Centered Design Approach

The electronic health record (EHR) targets systematized collection of patient-specific, electronically stored health data. The EHR is an evolving concept driven by ongoing developments and open or unclear legal issues concerning medical technologies, cross-domain data integration, and unclear access roles. Consequently, an interdisciplinary discourse based on representative pilot scenarios is required to connect previously unconnected domains. We address cross-domain data integration including access control using the specific example of a unique device identification (UDI)-expanded hip implant. In fact, the integration of technical focus data into the hospital information system (HIS) is considered based on surgically relevant information. Moreover, the acquisition of social focus data based on mobile health (mHealth) is addressed, covering data integration and networking with therapeutic intervention and acute diagnostics data. In addition to the additive manufacturing of a hip implant with the integration of a UDI, we built a database that combines database technology and a wrapper layer known from extract, transform, load systems and brings it into a SQL database, WEB application programming interface (API) layer (back end), interface layer (rest API), and front end. It also provides semantic integration through connection mechanisms between data elements. A hip implant is approached by design, production, and verification while linking operation-relevant specifics like implant-bone fit by merging patient-specific image material (computed tomography, magnetic resonance imaging, or a biomodel) and the digital implant twin for well-founded selection pairing. This decision-facilitating linkage, which improves surgical planning, relates to patient-specific postoperative influencing factors during the healing phase. A unique product identification approach is presented, allowing a postoperative read-out with state-of-the-art hospital technology while enabling future access scenarios for patient and implant data. The latter was considered from the manufacturing perspective using the process manufacturing chain for a (patient-specific) implant to identify quality-relevant data for later access. In addition, sensor concepts were identified to use to monitor the patient-implant interaction during the healing phase using wearables, for example. A data aggregation and integration concept for heterogeneous data sources from the considered focus domains is also presented. Finally, a hierarchical data access concept is shown, protecting sensitive patient data from misuse using existing scenarios. Personalized medicine requires cross-domain linkage of data, which, in turn, require an appropriate data infrastructure and adequate hierarchical data access solutions in a shared and federated data space. The hip implant is used as an example for the usefulness of cross-domain data linkage since it bundles social, medical, and technical aspects of the implantation. It is necessary to open existing databases using interfaces for secure integration of data from end devices and to assure availability through suitable access models while guaranteeing long-term, independent data persistence. A suitable strategy requires the combination of technical solutions from the areas of identity and trust, federated data storage, cryptographic procedures, and software engineering as well as organizational changes.

QKPT: Securing Your Private Keys in Cloud With Performance, Scalability and Transparency

Private key (e.g., RSA key) protection is a significant issue for cloud but existing keyless or keyguard solutions suffer from performance, elasticity or applicability limitations. Recently, represented by Intel KPT, a novel keyguard architecture emerges to combine trusted platform module and crypto accelerator for achieving both security and performance. However, the straight use of KPT for private key protection may not be a good fit in cloud as it incurs challenges on protection capacity, key provisioning latency and transparency. Based on KPT-like hardware, we propose QKPT, a comprehensive key management system to bring your own private keys (BYOPK) into multi-tenant clouds. QKPT introduces a carefully-designed key wrapping layer to overcome these challenges. A small symmetric wrapping key (SWK) is generated for each tenant as the master key to resolve the former two challenges, while a special private key wrapping scheme is adopted to resolve the transparency limitation. Additionally, QKPT incorporates certificate trust to enhance the security of the SWK lifecycle and provides a hardened key server solution without expensive HSM. The evaluation shows that QKPT has a low runtime overhead ( <inline-formula><tex-math notation="LaTeX">$\leq$</tex-math></inline-formula> 1.2% for SSL/TLS handshakes) and still greatly outperforms the software baseline (3.5x-17x) owing to the crypto offloading.

Analysis of CFRP-confined CFST columns reinforced with steel angles under axial compression

To study the axial compression properties of specimens of concrete-filled steel tubes reinforced with steel angles, abbreviated as SRCFST, and of specimens of FRP-confined SRCFST, abbreviated as F-SRCFST, relevant finite element (FE) models were established using ABAQUS software. For verifying the accuracy of the proposed FE models, the axial load carried by each component of the specimen was first analysed and the distribution rules of the contact pressure between the steel tube and concrete as well as between the steel angles and concrete were analysed. In the second phase, the important parameters, such as the yield strength and wall thickness of the steel tube, the yield strength and cross-sectional area of the steel angles, the tensile strength and number of FRP wrapping layers were analysed. The third phase consisted of creating and proposing the design formulas for the SRCFST and F-SRCFST specimens on the basis of parametric analyses and numerical fitting method. The research results indicate that FRP has a minimal effect on the axial carrying capacity of the steel tube and the fundamental effect for the improved ultimate load is the indirect confinement effect by the FRP on the concrete. The proposed design formulas can accurately predict the ultimate load of SRCFST and F-SRCFST specimens, and the calculation error is generally within 10%.

Octadecane filled bubble wrap as phase change material layers to smooth temperature variations of buildings during summer time. An experimental study

Phase change materials (PCM) have good potential to be used in passive thermal energy systems to mitigate the temperature variations of buildings. Octadecane wax, with a 28 °C solid/liquid transition temperature and high fusion/crystallization enthalpy of 240 J/g is a good PCM candidate to improve the thermal management of living spaces because the comfort temperature is typically between 25 °C and 30 °C. To validate experimentally the capacity of octadecane to smooth the temperature variations around the comfort temperature, polyethylene bubble wrap, a standard insulating layer found in building structures is used as octadecane container support. About 1.5 L of wax per square meter of bubble wrap can be retained in a single layer of this insulating film, giving about 260 kJ/m2 of latent energy. A true daily temperature cycle, corresponding to a typical summer day in Los Angeles, is used to study the temperature gaps and delays induced by the octadecane filled bubble wrap. Stacking several layers of this PCM wrap makes warming/cooling delays and temperature gaps to increase rapidly. Indeed, four layers give about 1000 kJ/m2 of latent energy and prevent the temperature on the back side of the stack to exceed the fusion temperature of octadecane for more than 10 h. When the « outside » temperature is at its maximum at midday, the temperature difference between the two faces of the stack reaches −2.8 °C. A comfortable 28 °C temperature is maintained during 12 h while, in the same time, the « outside » temperature moves from 30 °C to 22 °C with a peak over 32 °C. This work was performed using only bubble wrap layers, without considering a representative wall or roof structure. In this case, a lower amount of PCM wax would be needed for a similar impact because the other parts of the structure will also play an important role in the thermal dynamic of the building.

The Impact of Sterile Instrument Set Wrapping Defects on Trauma and Orthopaedic Surgery Theatre Lists.

Introduction Surgical site infections (SSIs) are a universally dreaded complication of any surgical procedure. The goal of this single-center study was to examine the issue of orthopaedic instrument wrapping defects with a focus on the importance of a high level of surveillance to enable identification of these defects in order to reduce the risk of instrument contamination. We also evaluated the impact on patient care, theatre staff, hospital finances and resource utilization during a defined study period in order to stimulate critical discussion and further research into potentially eliminating this problem via change in practice and advances in technology. To the best of our knowledge, this will be the first paper that looks at this problem from the above perspective within the United Kingdom National Health Service. Methods We conducted a prospective service evaluation project over a 30-week period from December 2021 to July 2022 across our three hospital sites within the United Kingdom National Health Service.We collated data on defects found in orthopaedic instrument wrappings as detected by visual inspection under ambient or theater lighting and the resulting surgical case cancellations. Defect types included in the study were all puncture holes, abrasions or tears visible to the naked eye irrespective of their size. Results A total of 601 orthopaedic sets were rejected during the study period due to defects identified in the sterile instrument wrappings. Of these, 437 were due to holes/tears in the wrapping, 129 were due to wet inner wrappings and 35 were due to insecure wrappings. This directly resulted in same-day cancellation of 13 surgical cases or 0.27% of booked cases with extra sets required for the other affected cases. These 13 cases could not proceed as they involved loan kits where no remedial action could be taken. Remedial action was required for the other 588 operation list cases affected by the sterile wrapping defects. The majority of the identified defects and resulting theatre case cancellations (61.5%) were in hip and knee arthroplasty surgery. The calculated potential financial loss due to these problems was £145,000 over the seven-month study period. This financial cost is equivalent to the best practice top-up tariff in England for treating approximately 108 hip fracture patientsbased on £1,335 per patient. Conclusion Our study identified defects in the sterile instrument wrappings affecting both the inner with or without involving theouter wrapping layerand resulting in cancellation of elective and trauma orthopaedic cases with resultant clinical and financial implications. There is a need to be more vigilant in identifying defects in drapes. Further research is warranted to improve ways of identifying defects in sterile wrappings and devise new protective mechanisms during sterilisation that can eliminate the use of sterile instrument wrappings.

Large-Area Hexagonal Boron Nitride Layers by Chemical Vapor Deposition: Growth and Applications for Substrates, Encapsulation, and Membranes

ConspectusHexagonal boron nitride (hBN) has emerged as a promising two-dimensional (2D) material because of its unique optical properties in the deep-UV region, mechanical robustness, thermal stability, and chemical inertness. Ultrathin hBN layers have gained significant scientific attention for various applications, including nanoelectronics, photonics, single photon emission, anticorrosion, and membranes. For example, the carrier mobility of graphene- and MoS2-based transistors can be improved by using an hBN encapsulation layer, which protects graphene or MoS2 from air and/or screens the charge trap site of a substrate. Moreover, deep-UV emitters and detectors have been developed on the basis of the large bandgap of hBN (∼6 eV), which exhibits a sharp absorption at approximately 200 nm. Additionally, oxidation of metal surfaces can be prevented by hBN encapsulation, and proton transport can be facilitated by hBN membranes with low gas permeability. Wafer-scale growth of hBN films is crucial to enable their industrial-scale applications. In this regard, chemical vapor deposition (CVD) is a promising method in which scalable high-quality films can be grown at reasonable cost. To date, considerable efforts have been made to develop continuous hBN thin films with high crystallinity, from those with large grains to single-crystal ones, and to realize thickness control of hBN films by CVD. However, the growth of wafer-scale high-crystallinity hBN films with precise thickness control has not been reported yet. The hBN growth is significantly affected by the substrate, in particular the type of metals, because the intrinsic solubilities of boron and nitrogen depend on the type of metal; moreover, control of the grain size and thickness of hBN is difficult. Although growth mechanisms for various substrates have been proposed using various control experiments, a precise growth mechanism has not yet been established through systematic studies. Thus, a deeper understanding of the CVD-based growth of hBN is critical.In this Account, state-of-the-art strategies adopted for growing wafer-scale, highly crystalline hBN are summarized, followed by the proposed mechanisms of hBN growth on catalytic substrates. Furthermore, various applications of the hBN thin films fabricated in our laboratory are demonstrated, including a dielectric layer, an encapsulation layer, a wrapping layer of gold nanoparticles for surface enhanced Raman scattering, a proton-exchange membrane, a template for growth of other 2D materials or nanomaterials, and a platform of fabricating in-plane heterostructures. Finally, the inherent challenges are summarized, and future research directions for the facile CVD-based growth of single-crystal hBN are proposed, including the development of a transfer method that is effective for various applications.

Morphological and functional characterizations of SnO2 electron extraction layer on transparent conductive oxides in lead-halide perovskite solar cells

Optimization of carrier extraction and/or transport layers is an important factor for the development of perovskite semiconductor devices. In particular, tin dioxide, SnO2, is being frequently used as an electron transport layer (ETL) in perovskite solar cells. However, a systematic study on preparation and characterization of the SnO2-ETL is still lacking, and thus, morphological and electronic-functional roles are not fully understood. In this paper, we systematically investigate the SnO2-ETL prepared on fluorine-doped tin oxide (FTO) substrates by a spin-coating technique. Using microscopic observations, we morphologically study how the SnO2 film covers the FTO surface with large unevenness. Optical characterizations are employed for investigating an electronic band alignment of the perovskite/SnO2 interface varied with the SnO2 concentration in a solution. Furthermore, we systematically evaluate photovoltaic properties of FTO-based solar cell devices. A major finding from these investigations is the fact that while the SnO2-ETL prepared at the adequate condition exhibits an ideal band alignment, the excessive SnO2 deposition causes a poor electron extraction and device performance degradation. Furthermore, we show that the spin-coated SnO2-ETL can cover the FTO surface as an ultrathin wrapping layer. These results highlight the importance of the SnO2-ETL and pave the way for optoelectronic device applications of perovskite materials.