Search

Carbon paper is one of the most widely used gas diffusion layer substrate materials due to its stable performance, relatively low cost, and easy for subsequent processing. Water-soluble phenolic resin, which is more ecologically friendly than alcohol-soluble phenolic resin, was used to prepare carbon paper as the precursor of the carbon matrix. And the effect of different resin solution concentrations on the properties of carbon paper was explored. The results showed that the graphitization, electrical conductivity and mechanical properties of carbon paper increased with the increase of resin solution concentration. When the concentration of resin solution was 20 wt%, the performance of carbon paper was relatively optimal. The graphitization of the carbon paper reached 65.45%, the porosity reached 80.74%, the resistance value at 1 MPa pressure was only 7.61 mΩ cm2, the tensile strength was 1.57 MPa, and the elastic modulus was 1210.98 MPa. [ABSTRACT FROM AUTHOR]

Enzymes derived from microbial sources have gained increasing popularity in industrial applications over the past decades. Despite the high production cost, alkaline proteases have wide applications in industries such as tanneries, food production, and detergents. In recent years, there has been a shift towards utilizing natural carbon sources for cultivating microorganisms and extracting proteases in order to reduce production costs. This study aimed to investigate the biochemical and kinetic properties of protease enzymes obtained from Aspergillus niger cultivated in a paper waste medium and compare with the enzyme produced in a basal medium. Glucose is a more favorable carbon source compared to cellulose, so paper waste was pretreated with cellulose-degrading bacteria to convert cellulose into smaller carbohydrates. After the growth of A. niger in basal and combinational media, the enzymatic properties were compared between the extracted enzymes by using casein as substrate. The results demonstrated that A. niger could produce protease enzymes in the paper waste medium similar to the basal medium with more than 5-fold cost saving. The specific activity of the enzymes isolated from the basal and paper waste media was calculated to be 184.95 ± 10.56 U ml−1 and 169.88 ± 11.05 U ml−1, respectively. Carbon sources did not affect the optimum pH and temperature of the protease enzyme, which were found to be 8 and 37 °C, respectively. This study provides valuable insights into the production of alkaline protease from A. niger using a combinational medium (paper waste pretreated by cellulose-degrading bacteria), offering a cost-effective approach for industrial applications. [ABSTRACT FROM AUTHOR]

Despite incredible growth in systems of care and rapidly expanding therapeutic options for people with inflammatory bowel disease, there are significant barriers that prevent patients from benefiting from these advances. These barriers include restrictions in the form of prior authorization, step therapy, and prescription drug coverage. Furthermore, inadequate use of multidisciplinary care and inflammatory bowel disease specialists limits patient access to high-quality care, particularly for medically vulnerable populations. However, there are opportunities to improve access to high-quality, patient-centered care. This position statement outlines the policy and advocacy goals that the American Gastroenterological Association will prioritize for collaborative efforts with patients, providers, and payors. [ABSTRACT FROM AUTHOR]

Bibliometric analysis of highly cited papers facilitates researchers in formulating strategic research possibilities and addressing gaps in specific domains. In this context, a bibliometric analysis was conducted to identify published papers on "oral mucosal lesions in COVID-19" within medical literature. A comprehensive search was performed in the Scopus database in July 2023. Relevant articles were retrieved, reviewed, and data for the bibliometric analysis was recorded. Network visualization of authors, countries, and keywords was generated using VOSviewer software. The analyzed articles were published over the last three years, from 2020 to 2023, with the highest output observed in 2021. The citation count for individual papers ranged from 1 to 340, with a mean of 22.325 ± 58.93 citations. A total of 37 journals were involved in publishing papers on this topic, and five authors each contributed three papers. Notably, Brazil made the highest number of contributions with eight papers. Among the 40 papers, 19 were review papers and 16 were articles discussing various aspects of oral mucosal lesions in COVID-19 patients. Additionally, six papers were identified as systematic reviews, designated with a high level of evidence. This study presents a comprehensive bibliometric analysis of papers published on "oral mucosal lesions in COVID-19." The findings will assist researchers in identifying impactful papers, understanding the prevailing research trends, and guiding future research directions in this domain. The insights gained from this analysis can contribute significantly to advancing knowledge and improving patient care in this critical area of study. • First comprehensive bibliometric analysis on "oral mucosal lesions in COVID-19" in medical literature. • Offers valuable insights to researchers for strategic planning and further exploration in this domain. • Thoroughly examined articles from 2020 to 2023, with a peak in output observed in 2021. • Six systematic reviews among 40 papers, indicating high-quality evidence-based studies. • Brazil emerged as the top contributor with eight papers on the subject. [ABSTRACT FROM AUTHOR]

In recent years, the research pertaining to speech recognition technology in the Kazakh language has gained significant importance. This is due to the increasing demand for natural language processing applications in the region where Kazakh is predominantly spoken. Thus, there exists an urgent requirement for precise and dependable speech recognition systems. The research study examines the application of sophisticated deep learning methodologies, such as Natural Language Processing (NLP) and Hidden Markov Model (HMM), in facilitating speech recognition for the Kazakh language. Additionally, the investigation delves into how various techniques, including data preprocessing, acoustic modeling, and language modeling, can aid in devising effective speech recognition systems. The article deliberates on the feasible uses of speech recognition technology in the geographic area where Kazakh language is spoken and outlines its future research prospects. The investigation underscores the significance of persistent inquiry in this realm to confront distinctive obstacles encountered in creating speech recognition systems for languages with restricted resources. [ABSTRACT FROM AUTHOR]

This paper describes the fabrication and characterization of porous SiC ceramics derived from highly-filled preceramic papers. The SiC ceramics were obtained by spark plasma sintering of stacked preceramic papers at temperatures of 2100 and 2200 °C under pressures of 5–60 MPa for 10 min. The microstructure and phase composition were analyzed by scanning electron microscopy and X-ray diffraction, respectively. Gas permeation tests were performed using hydrogen permeation cell at room temperature. It is revealed that the porosity of sintered SiC can be varied from 9 to 45 % depending on the sintering parameters. The shrinkage of the materials during spark plasma sintering occurs in four stages. The linear shrinkage value of the material increases from 7 to 47 % at 2100 °C and from 20 to 50 % for the samples sintered at 2100 and 2200 °C, respectively. Correlation dependencies between porosity and mechanical properties of the fabricated SiC were established. The obtained porous SiC ceramics exhibit high bending strength of 165 MPa and gas permeation flux of 78 molH 2 /m2/s at the porosity of 36 % that make it suitable for ceramic-based membranes. [ABSTRACT FROM AUTHOR]

Aerogel composites reinforced by fibers have found extensive applications in the field of thermal insulation and energy conservation. However, the composites are hindered by their high infrared radiation transmittance and weak interface adhesion in practical applications. Herein, we designed and prepared a novel thin composite called 'fiber/whisker/aerogel paper' (SWAP) with a thickness of less than 1 mm. The SWAP integrated SiC nanowhiskers (SiC nw) as opacifiers and ultrafine SiO 2 fibers as reinforcement, fabricated through wet manufacturing and sol-gel process. The 'fiber/aerogel paper' (SAP) and SWAP exhibited low thermal conductivity at room temperature, measuring 0.025 W/(m·K) and 0.033 W/(m·K), respectively. Additionally, they exhibited low densities of 0.195 g/cm3 and 0.225 g/cm3, respectively. Notably, SWAP exhibited excellent high-temperature insulation performance, primarily due to its low infrared transmittance (50% at 3 μm). The incorporation of SiC nw and ultrafine SiO 2 fibers collectively enhanced the interfacial adhesion with the aerogel matrix even amidst rigorous testing (weight loss less than 3%). SWAP also demonstrated flexibility, high thermal stability, hydrophobicity, and flame resistance. Furthermore, a comprehensive investigation into the performance variations and influencing g factors of the material was conducted under different heat treatment conditions. This research provides guidance for the application of such materials under high temperatures. [ABSTRACT FROM AUTHOR]

The ZrO 2 fiber paper exhibits excellent thermal insulation properties, however, its limited mechanical strength and insufficient thermal stability hinder its widespread applications. The composite fiber papers, using mullite fibers possessing a high aspect ratio and exceptional thermal stability combined with ZrO 2 fibers, were fabricated via a vacuum-assisted filtration method. This method involved the successive stacking of composite fibers with alumina sol, using vacuum-induced directed water flow to create a layered structure reminiscent of nacre. The layered structure of the nacre, which demonstrates remarkable strength and hardness, has also served as a source of inspiration for the architectural design of the fiber paper. The tensile strength of pure ZrO 2 fiber paper was significantly enhanced by the addition of 7 wt% mullite fibers, resulting in a remarkable increase to 0.1805 kN/m. The paper exhibited exceptional resistance to bending, maintaining 96 % of its bending strength even after undergoing 100 cycles. The thermal shrinkage of the composite paper, containing 15 wt% mullite fibers, was reduced from 17.75 % observed in pure ZrO 2 fiber paper to a mere 1.32 % after undergoing heat treatment at a temperature of 1300 °C for 2 h. The composite paper, measuring 5 mm in thickness and consisting of 7 wt% compositions, displayed exceptional thermal insulation properties when exposed to a hot side temperature of 1370 °C. It effectively insulated temperatures up to approximately 1000 °C. [ABSTRACT FROM AUTHOR]

[Display omitted] • Designing materials using rice-leaf-mimetic paper as a substrate. • Engineering rice-leaf-mimetic paper with hydrochromic dyes or biolubricants. • Processes based on mass-producible papermaking unit operations. Biomimetics has revolutionized materials innovation by drawing inspiration from biological systems. Cellulosic paper, a sustainable biomaterial, offers immense potential for biomimetic research. Paper-based biomimetic materials, which replicate the structures and functionalities of natural materials by utilizing the cellulosic fiber network as a substrate or skeleton, provide customizable functional properties, thereby enabling advanced applications. Here, we introduce rice-leaf-mimetic paper, inspired by the leaf's microstructure and biowax-based cuticle. This paper exhibits self-cleaning superhydrophobicity and showcases possibilities for additional functionalities, including antibacterial properties and food preservation, as evidenced in our prior research. We propose its utilization as a substrate for rewritable and biolubricant-infused surfaces. These somehow distinct surfaces draw inspiration from the chemistry and microstructure of the rice leaf. Although incorporating hydrochromic dyes enables rewritability, controlling the retention time of colors remains challenging. The biowaxy structure of the paper prolongs color maintenance by inhibiting water evaporation. Moreover, the hierarchically rough microstructure of rice-leaf-mimetic paper effectively stores biolubricant molecules, reducing friction and enhancing slipperiness. Surface microcavity ratio analysis provides insights into the paper's biolubricant-storability. The surface engineering of rice-leaf-mimetic paper using hydrochromic dyes or biolubricants holds potential for designing novel materials. Unveiling the vast potential of easily scalable papermaking processes alongside biomimetics and surface engineering opens new avenues for materials innovation. [ABSTRACT FROM AUTHOR]

• Liquid water saturation in carbon paper is measured • Quantifies the capillary trapping effect of isolated water drops in carbon papers • Proposes a model describing liquid water drops transport In previous macroscopic average models of proton exchange membrane fuel cells (PEMFCs), liquid water was assumed to be continuous throughout the carbon paper. The transport of disconnected water drops in carbon paper has long been neglected in these models, which tend to underestimate water saturation in carbon paper. This study proposes a two-phase flow model that considers the transport of disconnected water drops to simulate the air-water transport in carbon paper. The proposed model was established based on the relationship between capillary force and liquid water saturation, and this relationship was obtained by conducting centrifuge experiments. In the centrifuge experiment, initially, the water saturation inside the carbon paper sample was one, and the centrifugal acceleration was zero. As the centrifugal acceleration increased, the water saturation decreased owing to the centrifugal force. After twenty seconds, the water saturation no longer decreases because the centrifugal force on the liquid water is balanced by the capillary force. Centrifugal acceleration was used to evaluate the capillary force. When the centrifugal acceleration was 185 m s − 2 , the saturation of the water drops in the balanced state was 32.0%. As the centrifugal acceleration increases to 739 m s − 2 , the saturation decreases to 6.5%. According to the experimental results, a function correlating the saturation and centrifugal acceleration, that is, the capillary force, was established. Finally, the results show that the centrifugal acceleration is more than 18.5 times that of the gravitational acceleration, indicating that the effect of gravity on the motion of water drops is negligible. [Display omitted] [ABSTRACT FROM AUTHOR]