Effects of Organic Acids on the Extraction and Properties ofAcid-soluble Collagen from Tilapia Skin

The effects of three organic acids, namely, acetic acid (AA), tartaric acid (TA), and citric acid (CA), on the structure and properties of acid-soluble collagen (ASC) from tilapia skin were compared in this study. The secondary structure of the collagen samples was analyzed by circular dichroism (CD) spectrometry and Fourier transform infrared spectroscopy (FTIR). The thermal stability of the collagen samples was determined by differential scanning calorimetry (DSC), and the fibroblast ability of ASC was analyzed. Results showed that, the extraction yields of AA-ASC, TA-ASC and CA-ASC were 15.87%, 17.69%, and 28.63%, respectively. The content of triple helical conformation of AA-ASC was similar to that of CA-ASC, which was higher than that of TA-ASC. The FTIR data showed that AA-ASC had the highest hydrogen bond content, followed by CA-ASC and TA-ASC. No significant difference was found in the thermal transition temperature (Tm) of the extracted three collagens, but the enthalpy values of AA-ASC, TA-ASC, and CA-ASC were 1.18, 0.73, and 0.35 J/g, respectively. The fibrogenesis experiment revealed that AA-ASC had the highest fibril-forming rate and absorbance, followed by CA-ASC and TA-ASC. The results of this study suggest that the number and dissociation constant of carboxylic acids may play an important role in the effect of organic acids on the extraction and properties of collagen from tilapia skin

Anti-parity-time topologically undefined state

We constructed an anti-parity-time-symmetric photonic lattice by using perturbations. The results show the topological state will appear when the waveguide coupling constants $\kappa_1<\kappa_2$; Interestingly, a state with undefined winding numbers occurs when $\kappa_1=\kappa_2$, in which the light distributes only in the wide waveguides with equal magnitude distribution. Further studies show that the edge state will be strengthened by introducing defect for the topologically non-trivial case, while it will not affect the equal intensity transmission for the topologically undefined state. Our work provides a new way to realize the topological state and equally divided light transmission and might be applicable in optical circuits and optical interconnect

Bibliometric and visual analysis of RAN methylation in cardiovascular disease

BackgroundRNA methylation is associated with cardiovascular disease (CVD) occurrence and development. The purpose of this study is to visually analyze the results and research trends of global RNA methylation in CVD.MethodsArticles and reviews on RNA methylation in CVD published before 6 November 2022 were searched in the Web of Science Core Collection. Visual and statistical analysis was performed using CiteSpace 1.6.R4 advanced and VOSviewer 1.6.18.ResultsThere were 847 papers from 1,188 institutions and 63 countries/regions. Over approximately 30 years, there was a gradual increase in publications and citations on RNA methylation in CVD. America and China had the highest output (284 and 259 papers, respectively). Nine of the top 20 institutions that published articles were from China, among which Fudan University represented the most. The International Journal of Molecular Sciences was the journal with the most studies. Nature was the most co-cited journal. The most influential writers were Zhang and Wang from China and Mathiyalagan from the United States. After 2015, the primary keywords were cardiac development, heart, promoter methylation, RNA methylation, and N6-methyladenosine. Nuclear RNA, m6A methylation, inhibition, and myocardial infarction were the most common burst keywords from 2020 to the present.ConclusionsA bibliometric analysis reveals research hotspots and trends of RNA methylation in CVD. The regulatory mechanisms of RNA methylation related to CVD and the clinical application of their results, especially m6A methylation, are likely to be the focus of future research

Multiple organ infection and the pathogenesis of SARS

After >8,000 infections and >700 deaths worldwide, the pathogenesis of the new infectious disease, severe acute respiratory syndrome (SARS), remains poorly understood. We investigated 18 autopsies of patients who had suspected SARS; 8 cases were confirmed as SARS. We evaluated white blood cells from 22 confirmed SARS patients at various stages of the disease. T lymphocyte counts in 65 confirmed and 35 misdiagnosed SARS cases also were analyzed retrospectively. SARS viral particles and genomic sequence were detected in a large number of circulating lymphocytes, monocytes, and lymphoid tissues, as well as in the epithelial cells of the respiratory tract, the mucosa of the intestine, the epithelium of the renal distal tubules, the neurons of the brain, and macrophages in different organs. SARS virus seemed to be capable of infecting multiple cell types in several organs; immune cells and pulmonary epithelium were identified as the main sites of injury. A comprehensive theory of pathogenesis is proposed for SARS with immune and lung damage as key features

Evidence for an Excitonic Insulator State in Ta2_2Pd3_3Te5_5

The excitonic insulator (EI) is an exotic ground state of narrow-gap semiconductors and semimetals arising from spontaneous condensation of electron-hole pairs bound by attractive Coulomb interaction. Despite research on EIs dating back to half a century ago, their existence in real materials remains a subject of ongoing debate. In this study, through systematic experimental and theoretical investigations, we provide evidence for the existence of an EI ground state in a van der Waals compound Ta$_2$Pd$_3$Te$_5$. Density-functional-theory calculations suggest that it is a semimetal with a small band overlap, whereas various experiments exhibit an insulating ground state with a clear band gap. Upon incorporating electron-hole Coulomb interaction into our calculations, we obtain an EI phase where the electronic symmetry breaking opens a many-body gap. Angle-resolved photoemission spectroscopy measurements exhibit that the band gap is closed with a significant change in the dispersions as the number of thermally excited charge carriers becomes sufficiently large in both equilibrium and nonequilibrium states. Structural measurements reveal a slight breaking of crystal symmetry with exceptionally small lattice distortion in the insulating state, which cannot account for the significant gap opening. Therefore, we attribute the insulating ground state with a gap opening in Ta$_2$Pd$_3$Te$_5$ to exciton condensation, where the coupling to the symmetry-breaking electronic state induces a subtle change in the crystal structure.Comment: 10 pages, 5 figure

Facile synthesis of Bi2Fe4O9@C composite as new high-performance anode materials for lithium-ion batteries

Faced with the increasing demand for energy density of lithium-ion batteries in the market, exploring new electrode materials is an effective way to pursue higher energy density of lithium-ion batteries. Herein, Bi2Fe4O9@C is prepared by solid state reaction in combination with mechanical ball milling. The morphology, microstructure and properties of the negative electrode Bi2Fe4O9@C of lithium ion battery were studied. As expected, the electrochemical performance of Bi2Fe4O9@C is enhanced by composite with graphite. Electrochemical tests show that the reversible charging capacity of Bi2Fe4O9@C is 743 mAh g(-1) after 80 cycles at a current density of 100 mA g(-1), while the pure Bi2Fe4O9 compound retains only 142 mAh g(-1). Especially, the reversible delithiation capacity of Bi2Fe4O9@C composite is up to 551 mAh g(-1) at 2 A g(-1). This study demonstrates the potential application of Bi2Fe4O9@C composite in anode materials for lithium-ion batteries

Carbon-coated BiVO4 prepared by molten salt method combined with ball milling for high-performance lithium-ion battery anode

Because of its high theoretical capacity, BiVO4 is expected to be employed in lithium-ion battery anodes. Herein, carbon-coated BiVO4 (BiVO4@C) nano-composite was prepared through molten salt method accompanied by high-energy planetary milling and investigated as an anode material for Li-ion batteries. X-ray diffraction, scan electron microscopy, and transmission electron microscope were used to study the crystallization and microstructure of the samples. Moreover, compared with pure BiVO4, the BiVO4@C electrode shows competitive electrochemical performance with a reversible capacity of 700 mAh g(-1) over 200 cycles at 100 mA g(-1). It also exhibits stable long cycle life with delithiation capacity of 531 mAh g(-1) after 500 cycles at 200 mA g(-1) and 340 mAh g(-1) after 1200 cycles at 500 mA g(-1). The molten salt method combined with ball milling can be used as a new method to synthesize BiVO4@C anode material for lithium-ion batteries

Opportunistic maintenance policies for multi-machine production systems with quality and availability improvement

International audienceEffective maintenance policies can improve the production system performance by alleviating product quality degradation and increasing system reliability and availability. However, reliability, product quality degradation, and availability are conflicting optimization objectives and are rarely considered together in maintenance policy optimization. Aiming at optimizing these three objectives simultaneously, this paper proposes a joint model for opportunistic maintenance (OM), and product quality and availability improvement of a series multi-machine production system (MMPS). First, a condition index (CI) is developed to characterize the condition of individual machines based on monitoring data, and the corresponding threshold functions are developed to realize maintenance decision-making for individual machines. Then, considering maintenance dependence in the MMPS, based on the CI, the dual dynamic threshold functions are introduced: the preventive maintenance (PM) and the OM threshold functions, and a novel dual-dynamic-thresholds-based OM policy is developed. Whenever the CI of a machine reaches its PM threshold, all the other machines whose CI reaches the OM zone will be maintained together with this machine. Finally, a case study and comparisons are performed to show that the proposed model can simultaneously provide good production economic performance, high quality, and availability