Robust, Self-Healing, and Multi-Use Poly(Urethane-Urea-Imide) Elastomer as a Durable Adhesive for Thermal Interface Materials.

Currently, research on thermal interface materials (TIMs) is primarily focused on enhancing thermal conductivity. However, strong adhesion and multifunctionality are also important characteristics for TIMs when pursing more stable interface heat conduction. Herein, a novel poly(urethane-urea-imide) (PUUI) elastomer containing abundant dynamic hydrogen bonds network and reversible disulfide linkages is successfully synthesized for application as a TIM matrix. The PUUI can self-adapt to the metal substrate surface at moderate temperatures (80 °C) and demonstrates a high adhesion strength of up to 7.39 MPa on aluminum substrates attributed its noncovalent interactions and strong intrinsic cohesion. Additionally, the PUUI displays efficient self-healing capability, which can restore 94% of its original mechanical properties after self-healing for 6 h at room temperature. Furthermore, PUUI composited with aluminum nitride and liquid metal hybrid fillers demonstrates a high thermal conductivity of 3.87 W m-1 K-1 while maintaining remarkable self-healing capability and adhesion. When used as an adhesive-type TIM, it achieves a low thermal contact resistance of 22.1 mm2 K W-1 at zero pressure, only 16.7% of that of commercial thermal pads. This study is expected to break the current research paradigm of TIMs and offers new insights for the development of advanced, reliable, and sustainable TIMs.

Analysis of ester-producing performance in high-yield ethyl hexanoate yeast and the effect on metabolites in bio- enhanced Daqu, the starter for Baijiu and other traditional fermented foods.

AIMS: Ethyl hexanoate, one of the key flavor compounds in strong-flavor Baijiu. To improve the content of ethyl hexanoate in strong-flavor Baijiu, a functional strain with high yield of ethyl hexanoate was screened and its ester-producing performance was studied. METHODS AND RESULTS: Upon identification, the strain was classified as Candida sp. and designated as ZY002. Under optimal fermentation conditions, the content of ethyl hexanoate synthesized by ZY002 can be as high as 170.56 mg L-1. A fermentation test was carried out using the ZY002 strain bioaugmented Daqu to verify the role of the strain applied to Baijiu brewing. It was found that strain ZY002 could not only improve the moisture and alcohol contents of fermented grains but also diminish the presence of reducing sugar and crude starch. Furthermore, it notably amplified the abundance of flavor compounds. CONCLUSION: In this study, Candida sp. ZY002 with a high yield of ethyl hexanoate provided high-quality strain resources for the actual industrial production of Baijiu.

Expression patterns and pathogenesis of Semaphorin class 4 subfamily proteins in solid tumors.

Semaphorins are originally described as regulators of nervous system development. Besides, members of the semaphorin family play important roles in the growth, metastasis, and angiogenesis of solid tumors. In contrast to the other semaphorin subclasses, semaphorin class 4 has both membrane-bound and active soluble forms. Soluble class 4 semaphorins in body fluids (blood and saliva) may serve as potential biomarkers for early diagnosis and prognosis prediction of specific cancers. The class 4 semaphorins also transduce signal in cancer cells in a cell membrane-bound form, thereby regulating cancer progression. In solid tumors, class 4 semaphorins can act as ligands in active soluble forms, regulating cancer progression via autocrine and paracrine to activate signal transduction in cancer cells or endothelial cells in the tumor microenvironment. Targeting class 4 semaphorins may be a novel strategy for specific cancer therapy. However, the expression of class 4 semaphorins in solid tumors and the responsive pathogenesis are still controversial. Therefore, this review summarizes the specific expression regulation of class 4 semaphorin members in different types of solid tumors and the mechanisms involved in cancer progression.

Comprehensive Analysis of the SUMO-related Signature: Implication for Diagnosis, Prognosis, and Immune Therapeutic Approaches in Cervical Cancer.

SUMOylation, an important post-translational protein modification, plays a critical role in cancer development and immune processes. This study aimed to construct diagnostic and prognostic models for cervical cancer (CC) using SUMOylation-related genes (SRGs) and explore their implications for novel clinical therapies. We analyzed the expression profiles of SRGs in CC patients and identified 15 SRGs associated with CC occurrence. After the subsequent qPCR verification of 20 cases of cancer and adjacent tissues, 13 of the 15 SRGs were differentially expressed in cancer tissues. Additionally, we identified molecular markers associated with the prognosis and recurrence of CC patients, based on SRGs. Next, a SUMOScore, based on SRG expression patterns, was generated to stratify patients into different subgroups. The SUMOScore showed significant associations with the tumor microenvironment, immune function features, immune checkpoint expression, and immune evasion score in CC patients, highlighting the strong connection between SUMOylation factors and immune processes. In terms of immune therapy, our analysis identified specific chemotherapy drugs with higher sensitivity in the subgroups characterized by high and low SUMOScore, indicating potential treatment options. Furthermore, we conducted drug sensitivity analysis to evaluate the response of different patient subgroups to conventional chemotherapy drugs. Our findings revealed enrichment of immune-related pathways in the low-risk subgroup identified by the prognostic model. In conclusion, this study presents diagnostic and prognostic models based on SRGs, accompanied by a comprehensive index derived from SRGs expression patterns. These findings offer valuable insights for CC diagnosis, prognosis, treatment, and immune-related analysis.

Application of Situational Simulation Teaching Method in Respiratory and Cardiac Arrest Induced by Aspiration in Elderly Patients.

Background: Elderly hospitalized patients often have dysphagia, which can cause a variety of complications, the most common being aspiration. Early detection and timely treatment by nurses are needed in the clinic. Objective: To assess the effect of the situational simulation teaching method in respiratory and cardiac arrest induced by aspiration in elderly patients. Design: This was a retrospective study. Setting: This study was performed in the Department of Geriatrics, The Third Hospital of Hebei Medical University. Participants: Fifty patients with aspiration-induced respiratory and cardiac arrest who were hospitalized in our hospital were chosen and divided into 2 groups according to the composition of rescue nursing staff, and each group had 25 cases. Interventions: The patients who were rescued by nurses without scenario simulation training were the control group (routine emergency nursing group). The patients who were rescued by nurses trained via the scenario simulation teaching method were the experimental group. Primary Outcome Measures: (1) Emergency rescue time, (2) survival rate, (3) duration of adverse events, and (4) nursing satisfaction of patients. Results: Compared to the control group, the emergency rescue time, the duration of asphyxia, duration of respiratory and cardiac arrest, and the duration of malignant arrhythmias caused by cardiac arrest in the experimental group was lower (P < .05), while the survival rate and nursing satisfaction of patients in the experimental group was higher (P < .05). Conclusion: The application of situational simulation teaching method in the rescue of patients with respiratory and cardiac arrest has outstanding effects, which can effectively improve the efficiency of first aid, significantly improve the efficiency and standardization of first aid, and control or prevent the occurrence of poor prognosis, which is worth popularizing.

Evolution of fermented grain yeast communities in strong-flavored baijiu and functional validation of yeasts that produce superior-flavored substances.

BACKGROUND: Baijiu is a well-known alcoholic beverage in China and the quality is determined by various microorganisms during the fermentation process. Yeast is one of the most important microorganisms in the fermentation of baijiu. It has a strong esterification capacity and also affects the aroma. RESULTS: High-throughput sequencing results showed that the fermented grains (jiupei) during baijiu production were mainly composed of eight highly abundant yeast species. The species and abundance of yeasts changed significantly with the fermentation process. The flavor of 30 yeast strains in the jiupei was determined by a sniffing test and gas chromatography-mass spectrometry (GC-MS). The strain with the highest flavor substance content (2.34 mg L-1), named YX3205, was identified as Clavispora lusitaniae. Tolerance results showed that C. lusitaniae YX3205 can tolerate up to 15% (v v-1) ethanol. In a solid-state simulated fermentation experiment, the content of 24 flavor substances was significantly increased in the fortified group, and the total ester content reached 4240.73 µg kg-1, which was 2.8 times higher than that of the control group. CONCLUSION: The present study demonstrated the potential of C. lusitaniae YX3205 to enhance the flavor of baijiu, thereby serving as a valuable strain for the improvement of the flavor quality of baijiu. © 2024 Society of Chemical Industry.

Diabetes mellitus affects the treatment outcomes of drug-resistant tuberculosis: a systematic review and meta-analysis.

BACKGROUND: Both tuberculosis (TB) and diabetes mellitus (DM) are major public health problems threatening global health. TB patients with DM have a higher bacterial burden and affect the absorption and metabolism for anti-TB drugs. Drug-resistant TB (DR-TB) with DM make control TB more difficult. METHODS: This study was completed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline. We searched PubMed, Excerpta Medica Database (EMBASE), Web of Science, ScienceDirect and Cochrance Library for literature published in English until July 2022. Papers were limited to those reporting the association between DM and treatment outcomes among DR-TB and multidrug-resistant TB (MDR-TB) patients. The strength of association was presented as odds ratios (ORs) and their 95% confidence intervals (CIs) using the fixed-effects or random-effects models. This study was registered with PROSPERO, number CRD: 42,022,350,214. RESULTS: A total of twenty-five studies involving 16,905 DR-TB participants were included in the meta-analysis, of which 10,124 (59.89%) participants were MDR-TB patients, and 1,952 (11.54%) had DM history. In DR-TB patients, the pooled OR was 1.56 (95% CI: 1.24-1.96) for unsuccessful outcomes, 0.64 (95% CI: 0.44-0.94) for cured treatment outcomes, 0.63 (95% CI: 0.46-0.86) for completed treatment outcomes, and 1.28 (95% CI: 1.03-1.58) for treatment failure. Among MDR-TB patients, the pooled OR was 1.57 (95% CI: 1.20-2.04) for unsuccessful treatment outcomes, 0.55 (95% CI: 0.35-0.87) for cured treatment outcomes, 0.66 (95% CI: 0.46-0.93) for treatment completed treatment outcomes and 1.37 (95% CI: 1.08-1.75) for treatment failure. CONCLUSION: DM is a risk factor for adverse outcomes of DR-TB or MDR-TB patients. Controlling hyperglycemia may contribute to the favorite prognosis of TB. Our findings support the importance for diagnosing DM in DR-TB /MDR-TB, and it is needed to control glucose and therapeutic monitoring during the treatment of DR-TB /MDR-TB patients.

Machine discovery of partial differential equations from spatiotemporal data: A sparse Bayesian learning framework.

This study presents a general framework, namely, Sparse Spatiotemporal System Discovery (S3d), for discovering dynamical models given by Partial Differential Equations (PDEs) from spatiotemporal data. S3d is built on the recent development of sparse Bayesian learning, which enforces sparsity in the estimated PDEs. This approach enables a balance between model complexity and fitting error with theoretical guarantees. The proposed framework integrates Bayesian inference and a sparse priori distribution with the sparse regression method. It also introduces a principled iterative re-weighted algorithm to select dominant features in PDEs and solve for the sparse coefficients. We have demonstrated the discovery of the complex Ginzburg-Landau equation from a traveling-wave convection experiment, as well as several other PDEs, including the important cases of Navier-Stokes and sine-Gordon equations, from simulated data.

An Investigation of Signal Preprocessing for Photoacoustic Tomography.

Photoacoustic tomography (PAT) is increasingly being used for high-resolution biological imaging at depth. Signal-to-noise ratios and resolution are the main factors that determine image quality. Various reconstruction algorithms have been proposed and applied to reduce noise and enhance resolution, but the efficacy of signal preprocessing methods which also affect image quality, are seldom discussed. We, therefore, compared common preprocessing techniques, namely bandpass filters, wavelet denoising, empirical mode decomposition, and singular value decomposition. Each was compared with and without accounting for sensor directivity. The denoising performance was evaluated with the contrast-to-noise ratio (CNR), and the resolution was calculated as the full width at half maximum (FWHM) in both the lateral and axial directions. In the phantom experiment, counting in directivity was found to significantly reduce noise, outperforming other methods. Irrespective of directivity, the best performing methods for denoising were bandpass, unfiltered, SVD, wavelet, and EMD, in that order. Only bandpass filtering consistently yielded improvements. Significant improvements in the lateral resolution were observed using directivity in two out of three acquisitions. This study investigated the advantages and disadvantages of different preprocessing methods and may help to determine better practices in PAT reconstruction.

Electrochemically Determining Electronic Structure of ZnO Quantum Dots with Different Surface Ligands.

The electronic structure of quantum dots (QDs) including band edges and possible trap states is an important physical property for optoelectronic applications. The reliable determination of the energy levels of QDs remains a big challenge. Herein we employ cyclic voltammetry (CV) to determine the energy levels of three types of ZnO QDs with different surface ligands. Coupled with spectroscopic techniques, it is found that the onset potential of the first reductive wave is likely related to the conduction band edges while the first oxidative wave originates from the trap states. The determined specific energy levels in CV further demonstrates that the ZnO QDs without surface ligands mainly have oxygen interstitial defects whilst the ZnO QDs covered with ligands contain oxygen vacancies. The present electrochemical method offers a powerful and effective way to determine the energy levels of wide bandgap ZnO QDs, which will boost their device performance.

A handy imaging sensor array based on the phase transformation from CsPbBr3 to CsPb2Br5: highly sensitive and rapid detection of water content in ethanol.

Detection of the water content in ethanol has become very important in many fields; however, well-established methods usually require complex strategies and devices. Herein, a simple and non-instrument methodology was developed for the determination of the water content in ethanol. In this work, a CsPbBr3@PVA imaging array sensor was constructed based on the fluorescence on/off mechanism and applied to the detection of water content for the first time. When preparing CsPbBr3@PVA, the photoluminescence of CsPbBr3 was quenched by water in PVA due to the decomposition of CsPbBr3. By employing ethanol with fast volatilization to remove water, the decomposed composition recrystallized and formed luminescent CsPb2Br5. When the water content in ethanol was increased, the degree of the recovered fluorescence drastically reduced. To develop a portable and easily-operated methodology, the pictures of the sensor array were captured using a smartphone and quickly analyzed with ImageJ to read the gray-level values for each sample. The latter displayed a good linear relationship (R2 = 0.995) with the water content increasing from 0% to 7% in ethanol, and a low limit of detection of 0.006% was achieved. Moreover, the sensor array showed advantages like a fast response speed (5 s), strong selectivity and application potential in real samples. This method does not require expensive spectrometers and professional personnel to operate, having the virtues of low cost, fast detection and high sensitivity.

Direct growth of hBN/Graphene heterostructure via surface deposition and segregation for independent thickness regulation.

Hexagonal boron nitride/graphene (hBN/G) vertical heterostructures have attracted extensive attention, owing to the unusual physical properties for basic research and electronic device applications. Here we report a facile deposition-segregation technique to synthesize hBN/G heterostructures on recyclable platinum (Pt) foil via low pressure chemical vapor deposition. The growth mechanism of the vertical hBN/G is demonstrated to be the surface deposition of hBN on top of the graphene segregated from the Pt foil with pre-dissolved carbon. The thickness of hBN and graphene can be controlled separately from sub-monolayer to multilayer through the fine control of the growth parameters. Further investigations by Raman, scanning Kelvin probe microscopy and transmission electron microscope show that the hBN/G inclines to form a heterostructure with strong interlayer coupling and with interlayer twist angle smaller than 1.5°. This deposition-segregation approach paves a new pathway for large-scale production of hBN/G heterostructures and could be applied to synthesize of other van der Waals heterostructures.

An updated review on food-derived bioactive peptides: Focus on the regulatory requirements, safety, and bioavailability.

Food-derived bioactive peptides (BAPs) are recently utilized as functional food raw materials owing to their potential health benefits. Although there is a huge amount of scientific research about BAPs' identification, purification, characterization, and physiological functions, and subsequently, many BAPs have been marketed, there is a paucity of review on the regulatory requirements, bioavailability, and safety of BAPs. Thus, this review focuses on the toxic peptides that could arise from their primary proteins throughout protein extraction, protein pretreatment, and BAPs' formulation. Also, the influences of BAPs' length and administration dosage on safety are summarized. Lastly, the challenges and possibilities in BAPs' bioavailability and regulatory requirements in different countries were also presented. Results revealed that the human studies of BAPs are essential for approvals as healthy food and to prevent the consumers from misinformation and false promises. The BAPs that escape the gastrointestinal tract epithelium and move to the stomach are considered good peptides and get circulated into the blood using different pathways. In addition, the hydrophobicity, net charge, molecular size, length, amino acids composition/sequences, and structural characteristics of BAPs are critical for bioavailability, and appropriate food-grade carriers can enhance it. The abovementioned features are also vital to optimize the solubility, water holding capacity, emulsifying ability, and foaming property of BAPs in food products. In the case of safety, the possible allergenic and toxic peptides often exhibit physiological functions and could be produced during the hydrolysis of food proteins. It was also noted that the production of iso-peptides bonds and undesirable Maillard reaction might occur during protein extraction, sample pretreatments, and peptide synthesis.

Physicochemical and Colon Cancer Cell Inhibitory Properties of Theabrownins Prepared by Weak Alkali Oxidation of Tea Polyphenols.

Existing studies on the biological activity of theabrownins are not based on their free state but on the complexes of theabrownins, polysaccharides, proteins, and flavonoids. In this study, theabrownins (TBs-C) were prepared by weak alkali oxidation of tea polyphenols. The ultraviolet-visible scanning spectrum of TBs-C showed two characteristic absorption peaks at 203 and 270 nm. The zeta potential of the TBs-C aqueous solution was negative, and the values varied from - 6.26 to -19.55 mV with a solution pH of 3-9. Storage conditions of pH 5.0-7.0 and around 25 °C were beneficial for the physical and chemical stability of the TBS-C solution. Cells were treated with series concentrations and examined by MTT, HE staining, PI immunofluorescence staining, flow cytometry, and real-time PCR to investigate the antiproliferative effect of TBs-C on human colon cancer HT-29 cells. The results showed that TBs-C, particularly at 500 µg/mL, inhibited cell growth. TBs-C induced HT-29 cell apoptosis, as confirmed by morphological changes, nucleus propidium iodide staining, and distributions of the cell cycle. The apoptotic mechanism may be due to the intracellular redox imbalance induced by TBs-C.

Alfalfa (Medicago sativa L.) MsCML46 gene encoding calmodulin-like protein confers tolerance to abiotic stress in tobacco.

KEY MESSAGE: MsCML46 enhances tolerance to abiotic stresses through alleviating osmotic stress and oxidative damage by regulating the expression of stress-related genes to optimize osmolytes levels and antioxidant enzyme activity in transgenic tobacco. Abiotic stresses are major environmental factors that constraint crop productivity worldwide. Various stimuli regulate intracellular calcium levels and calcium-mediated signal transduction, and cellular responses. Ca2+ signals are perceived by different Ca2+ receptors. Calmodulin-like protein (CML) is one of the best-characterized Ca2+ sensors which shares sequence similarity with highly conserved calmodulin (CaM) ubiquitously expressed in plants. Currently, the molecular and physiological functions of CMLs are largely unknown. In this study, the MsCML46 was characterized in alfalfa (Medicago sativa cv. Zhaodong) under freezing stress. Results showed that MsCML46 was localized to the cytoplasm of Arabidopsis, and its expression was strongly elevated by cold, drought, salt, saline-alkali, and ABA treatments. Overexpressing MsCML46 in tobacco enhanced tolerance to freezing, drought, and salt stresses as evidenced by improved contents of osmotic regulatory solutes and antioxidant enzyme activity but decreased reactive oxygen species (ROS) accumulation. Furthermore, cold, drought, and salt stresses increased the expression of stress-related genes in transgenic tobacco. MsCML46 binds free Ca2+ to promote signal transduction and maintain higher K+/Na+ ratio. In this way, it protects intracellular homeostasis under sodium ion toxicity. These results suggest that MsCML46 plays a crucial role in resisting abiotic stresses and can be exploited in genetic engineering for crops.

Effects of aging on the quality of roasted sesame-like flavor Daqu.

BACKGROUND: Daqu, the saccharification, fermentation, and aroma-producing agents for Baijiu brewing, is prepared using a complex process. Aging is important for improving the quality of Daqu, but its impact has rarely been studied. This study investigated changes in the physicochemical properties, flavor compounds, and microbial communities during aging of Daqu with a roasted sesame-like flavor. RESULTS: The physicochemical properties changed continuously during aging to provide a high esterifying activity. Aging removed unpleasant flavor compounds and helped to stabilize the flavor compounds in mature Daqu. A high-throughput sequencing approach was used to analyze the changing composition of the microbial communities during aging. Aging helped to modify the microbial population to produce better Baijiu by eliminating low-abundance microbial communities and optimizing the proportion of predominant microbial communities. Nine genera of prokaryotic microbes formed the core microbiota in Daqu after aging. Regarding eukaryotic microbes, Zygomycota, the predominant community, increased in the first 2 months, then decreased in the third month of aging, while Ascomycota, the subdominant community, showed the opposite behavior. Absidia, Trichocomaceae_norank and Rhizopus were the predominant genera in the mature Daqu. CONCLUSIONS: Significant correlations between microbiota and physicochemical properties or flavor compounds were observed, indicating that optimizing microbial communities is essential for aging Daqu. This study provides detailed information on aging during Daqu preparation.

Alfalfa MsCBL4 enhances calcium metabolism but not sodium transport in transgenic tobacco under salt and saline-alkali stress.

KEY MESSAGE: MsCBL4 expression in tobacco enhanced its salt and saline-alkali stress tolerance by regulating calcium accumulation in roots, indicating the important role of calcium metabolism in plant saline-alkali stress tolerance The calcineurin B-like (CBL) family of proteins play important roles in plant abiotic stress tolerance and signal transduction. CBL4 is known to participate in the Salt Overly Sensitive pathway; however, little is currently known regarding the mechanisms underlying the response of CBL4 to saline-alkali stress. In this study, we cloned and characterized the alfalfa MsCBL4 gene. We found that MsCBL4 showed the highest expression in root tissues and was induced by salt and saline-alkali stress, with the latter causing higher induction. Overexpression of MsCBL4 in tobacco enhanced salt and saline-alkali stress tolerance and reduced the Na+/K+ ratio in roots of transgenic lines. Salt (30 and 300 mM NaCl) and saline-alkali (30 mM NaHCO3) stress assays performed for MsCBL4 transgenic tobacco lines revealed a substantial influx of sodium ions in roots under saline-alkali stress and indicated that the expression of MsCBL4 had little influence on sodium ion content reduction. In contrast, in roots subjected to saline-alkali stress, calcium accumulation occurred and was significantly enhanced by the overexpression of MsCBL4. Physiological and biochemical analyses indicated that MsCBL4 plays an important role in saline-alkali stress tolerance via its influence on the regulation of calcium transport and accumulation. These results provide novel insights into the saline-alkali stress tolerance mechanisms of plants.

Internet-Based Sharing Nurse Program and Nurses' Perceptions in China: Cross-Sectional Survey.

BACKGROUND: China is currently piloting a "Sharing Nurse" program that aims to increase the accessibility of nursing services to at-home patients by enabling patients to order nursing services using mobile apps or online platforms. OBJECTIVE: This study aims to assess nurses' perceptions of the Sharing Nurse program, including their acceptance, concerns, needs, and willingness to take part in the program. METHODS: A total of 694 nurses participated in the questionnaire survey. The survey collected their sociodemographic and work-related information and their perceptions of the Sharing Nurse program using a self-developed questionnaire. RESULTS: The 694 respondents agreed that the Sharing Nurse program could provide patients with better access to nursing care (n=483, 69.6%). Their main concerns about the program were unclear liability division when medical disputes occur (n=637, 90.3%) and potential personal safety issues (n=604, 87%). They reported that insurance (n=611, 88%), permits from their affiliated hospital (n=562, 81.0%), clear instructions concerning rights and duties (n=580, 83.6%), real time positioning while delivering the service (n=567, 81.7%), and one-key alarm equipment (n=590, 85.0%) were necessary for better implementation of the program. More than half of the respondents (n=416, 60%) had an optimistic attitude toward the development of the Sharing Nurse program in China. However, only 19.4% (n=135) of the respondents expressed their willingness to be a "shared nurse." Further analyses found that nurses with a master's degree or above (χ23=28.835, P<.001) or from tertiary hospitals (χ23=18.669, P<.001) were more likely to be aware of the Sharing Nurse program and that male nurses were more willing to be shared nurses (Z=-2.275, P=.02). CONCLUSIONS: The Chinese Sharing Nurse program is still in its infancy and many refinements are needed before it can be implemented nationwide. Generally, Chinese nurses are positive about the Sharing Nurse program and are willing to participate if the program is thoroughly regulated and supervised.

Mutagenesis of N-terminal residues confer thermostability on a Penicillium janthinellum MA21601 xylanase.

BACKGROUND: A mesophilic xylanase PjxA from Penicillium janthinellum MA21601 has high specific activity under acidic condition and holds great potential for applications in the animal feed industry. To enhance the thermostability of xylanase PjxA, two mutation strategies in the N-terminal region were examined and then integrated into the xylanase to further improvement. The recombinant xylanase PTxA-DB (The meaning of DB is disulfide-bridge.) was constructed by replacement of five residues in the mutated region in TfxA (T10Y, N11H, N12D, Y15F, N30 L), combined with an additional disulfide bridge in the N-terminal region. RESULTS: The Tm value of mutant PTxA-DB was improved from 21.3 °C to 76.6 °C, and its half-life was found to be 53.6 min at 60 °C, 107-fold higher than the wild type strain. The location of the disulfide bridge (T2C-T29C) was between the irregular loop and the ß-strand A2, accounting for most of the improvement in thermostability of PjxA. Further analysis indicated T2C, T29C, N30 L and Y15F lead to increase N-terminal hydrophobicity. Moreover, the specific activity and substrate affinity of PTxA-DB were also enhanced under the acidic pH values. CONCLUSIONS: These results indicated PTxA-DB could be a prospective additive to industrial animal feeds.

Sparse learning of partial differential equations with structured dictionary matrix.

This paper presents a "structured" learning approach for the identification of continuous partial differential equation (PDE) models with both constant and spatial-varying coefficients. The identification problem of parametric PDEs can be formulated as an ℓ1/ℓ2-mixed optimization problem by explicitly using block structures. Block-sparsity is used to ensure parsimonious representations of parametric spatiotemporal dynamics. An iterative reweighted ℓ1/ℓ2 algorithm is proposed to solve the ℓ1/ℓ2-mixed optimization problem. In particular, the estimated values of varying coefficients are further used as data to identify functional forms of the coefficients. In addition, a new type of structured random dictionary matrix is constructed for the identification of constant-coefficient PDEs by introducing randomness into a bounded system of Legendre orthogonal polynomials. By exploring the restricted isometry properties of the structured random dictionary matrices, we derive a recovery condition that relates the number of samples to the sparsity and the probability of failure in the Lasso scheme. Numerical examples, such as the Schrödinger equation, the Fisher-Kolmogorov-Petrovsky-Piskunov equation, the Burger equation, and the Fisher equation, suggest that the proposed algorithm is fairly effective, especially when using a limited amount of measurements.