Prevention of microbial colonization by advanced biochemical and biophysical methods

Bacterial-induced chronic infections remain a major clinical challenge, and especially biofilm-related diseases are still hard to be treated by existing means. As the workhorse against microorganism infections, antibiotics are hard to penetrate into biofilms, and the abuse of antibiotics caused the emergence of antimicrobial resistance (AMR) strains. Some infections are becoming challenging while the speed of identifying new antibiotics could not catch up with the speed of AMR bacterial strains generation. Thus, new materials with good activities of antibacterial and inhibit the formation of biofilm are necessary. Up to now, numerous methods have been used in applications against pathogens, while antibiotic treatment is the main mean. Meanwhile, scientists are still focusing on searching for other modes to replace the antibiotic treatment, such as biophysical decorations (changing the characteristics of the surface, such as the nature of the substrate, free energy of the surface, roughness, wettability, surface charge, and so on), electrochemical methods, photo-thermal therapies, and biomedical methods (antibiotic, metal elements, non-metal elements, organic compounds and so on). In this thesis, the antibacterial activities of different antimicrobial agents were tested, and various methods were jointly used to gain materials with satisfactory antibacterial properties. The thesis included analysis of eight antibacterial-related projects: 1) Mg discs (WE43), which had been reported to own antibacterial activity, were treated with DMEM and decorated with chitosan. Then, the silver-, copper-, and silicon-loaded bioglasses (Ag@BG, Cu@BG, and Si@BG) were coated onto the surface of the materials by the electrophoretic deposition (EPD) method. 2) Ti and Mg were mixed to form Ti-Mg metal composite (Ti-Mg MMC) alloys by spark plasma sintering (SPS) method. Furthermore, tannic acid (TA) was added to enhance the biocompatibility of Ti-Mg MMCs. 3) Chitosan (CS) was chelated with copper (II) as a complex material of Cu (II)-CS with antibacterial activity and metallic substrates were decorated with Cu (II)-CS nanoparticles by the electrophoretic deposition (EPD) method. 4) Mesoporous bioactive glass nanoparticles (MBGN) were synthesized and loaded with copper as an antibacterial element. As polyvinyl alcohols (PVA) are characterized by excellent physical properties, chemical resistance, biodegradability, biocompatibility, and non-toxicity, the formed Cu@MBGN were trapped in PVA to form a material with good antibacterial activity as a wound healing dressing. 5) Silver (Ag) nanoparticles were synthesized and loaded into mesoporous bioactive glass nanoparticles (MBGN). As reported, the strong antibacterial activity of Ag accompanies high cytotoxicity. The antibacterial property of Ag was proven in the experiment. Furthermore, bovine serum albumin (BSA), a serum albumin protein derived from cows, was added to the system to decrease the toxicity of Ag for further application. 6) Bacteriophages, bacteria-specific virues that can attach to bacterial host strains with high specificity, were conjugated onto synthesized mesoporous bioactive glass nanoparticles (MBGN) and aminopropyltriethoxysilane (APTES) modified MBGN (MBGN-APTES). The bound rates of phages with materials were measured and infective activities were tested. 7) Boron-doped diamond (BDD) electrodes were fabricated from niobium wires and assembled as a single instrument for implant cleaning against different microorganisms

Differential regulation of gastrulation and neuroectodermal gene expression by Snail in the Drosophila embryo

The initiation of mesoderm differentiation in the Drosophila embryo requires the gene products of twist and snail. In either mutant, the ventral cell invagination during gastrulation is blocked and no mesoderm-derived tissue is formed. One of the functions of Snail is to repress neuroectodermal genes and restrict their expressions to the lateral regions. The derepression of the neuroectodermal genes into the ventral region in snail mutant is a possible cause of defects in gastrulation and in mesoderm differentiation. To investigate such possibility, we analysed a series of snail mutant alleles. We found that different neuroectodermal genes respond differently in various snail mutant background. Due to the differential response of target genes, one of the mutant alleles, V2, that has reduced Snail function showed an intermediate phenotype. In V2 embryos, neuroectodermal genes, such as single-minded and rhomboid, are derepressed while ventral invagination proceeds normally. However, the differentiation of these invaginated cells into mesodermal lineage is disrupted. The results suggest that the establishment of mesodermal cell fate requires the proper restriction of neuroectodermal genes, while the ventral cell movement is independent of the expression patterns of these genes. Together with the data showing that the expression of some ventral genes disappear in snail mutants, we propose that Snail may repress or activate another set of target genes that are required specifically for gastrulation

Electrochemical Disinfection of Dental Implants Experimentally Contaminated with Microorganisms as a Model for Periimplantitis

Despite several methods having been described for disinfecting implants affected by periimplantitis, none of these are universally effective and may even alter surfaces and mechanical properties of implants. Boron-doped diamond (BDD) electrodes were fabricated from niobium wires and assembled as a single instrument for implant cleaning. Chemo-mechanical debridement and air abrasion were used as control methods. Different mono-species biofilms, formed by bacteria and yeasts, were allowed to develop in rich medium at 37 ◦C for three days. In addition, natural multi-species biofilms were treated. Implants were placed in silicone, polyurethane foam and bovine ribs for simulating different clinical conditions. Following treatment, the implants were rolled on blood agar plates, which were subsequently incubated at 37 ◦C and microbial growth was analyzed. Complete electrochemical disinfection of implant surfaces was achieved with a maximum treatment time of 20 min for Candida albicans, Candida dubliniensis, Enterococcus faecalis, Roseomonas mucosa, Staphylococcus epidermidis and Streptococcus sanguinis, while in case of spore-forming Bacillus pumilus and Bacillus subtilis, a number of colonies appeared after BDD electrode treatment indicating an incomplete disinfection. Independent of the species tested, complete disinfection was never achieved when conventional techniques were used. During treatment with BDD electrodes, only minor changes in temperature and pH value were observed. The instrument used here requires optimization so that higher charge quantities can be applied in shorter treatment timesITI Foundation, Switzerlan

Value of Kyoto gastritis score and modified prediction model in diagnosing Helicobacter pylori infection status under gastroscopy in Chinese population

Objective: To validate the application value of Kyoto gastritis score in diagnosing Helicobacter pylori (Hp) infection status under gastroscopy in Chinses population, and to construct a modified prediction model to improve the diagnostic value of Hp infection. Methods: A total of 749 cases who underwent gastroscopy at the Digestive Endoscopy Center of the Ninth People's Hospital (North), Shanghai Jiao Tong University School of Medicine, from January 1, 2021 to June 1, 2023 were retrospectively collected. Patients were divided into Hp-positive group and Hp-negative group based on histopathological biopsy or 13C breath test results. The endoscopic mucosal manifestations were recorded according to the Kyoto classification of gastritis, including atrophy, intestinal metaplasia, fold enlargement, diffuse redness, nodularity, RAC, red streak, and other 18 manifestations to verify the diagnostic value of Kyoto gastritis score for Hp infection. The mucosal manifestations with significant differences in univariate analysis were included in binary Logistic regression, and a modified prediction model was constructed according to the regression coefficients. ROC analysis was used to analyze the diagnostic value of Kyoto gastritis score and the modified prediction model for Hp infection. Results: The Hp infection rate was 54.47%. Intestinal metaplasia, fold enlargement, nodularity, diffuse redness, spotty redness, and sticky mucus were independent predictors of Hp infection. RAC, red streak, white and flat elevated lesion were independent predictors of Hp non-infection. The area under the curve was 0.861 (95%CI was 0.835~0.887), the accuracy was 75.2%, and the sensitivity and specificity were 88.5% and 65.1%. Mucosal manifestations such as spotty redness, sticky mucus, and RAC were incorporated into the modified prediction model. The results showed that the specificity (85.9%), positive predictive value (88.2%), negative predictive value (85.4%) and AUC [0.929 (95%CI was 0.910-0.947)] of the modified prediction model for Hp infection were higher than those of Kyoto gastritis score [65.1%, 75.2%, 82.5% and 0.861 (95%CI was 0.835-0.887), respectively]. Conclusions: Kyoto gastritis score has a certain application value for Hp in the Chinese population, and the modified prediction model has a higher diagnostic value for Hp infection

Heterogeneous impact of artificial intelligence on carbon emission intensity: Empirical test based on provincial panel data in China

IntroductionEnergy conservation and emission reduction, as a major policy of China for a long time, has been put on the key strategic position. Based on the panel data of 30 provinces, cities and districts in China from 2006 to 2019.MethodsThis paper uses fixed effect model and spatial Durbin model to explore the effect and mechanism of artificial intelligence (AI) on regional carbon emission intensity (CEI).ResultsThe results show that: (1) there is a significant inverted U-shaped between AI and CEI, that is, with the deepening of the development of AI, CEI first increases and then decreases. (2) There is a significant spatial correlation between the development of AI and CEI in China. (3) AI has a significant spatial spillover effect on CEI of adjacent regions, and it shows an inverted U-shaped track-from promoting to restraining.DiscussionThe conclusion provides policy implications for the formulation of AI development strategy and so on during the specific period

The impact of new digital infrastructure on green total factor productivity

As a new engine driving economic development, new digital infrastructure plays a significant role in enhancing green total factor productivity. Based on 2011–2020 panel data covering 30 Chinese provinces, this study empirically investigates the effects and mechanisms of new digital infrastructure on green total factor productivity. The results show that new digital infrastructure can significantly improve regional green total factor productivity, and this conclusion remains valid after a series of robustness tests and regressions of instrumental variables. Further mechanism research shows that new digital infrastructure indirectly promotes the growth of green total factor productivity by improving capital misallocation and driving technological innovation, while there is no mediating mechanism of labor misallocation. In addition, there is significant heterogeneity in the impact of new digital infrastructure on green total factor productivity. Especially during periods of high government attention, in the eastern regions, and in areas with higher levels of human capital, the positive incentive effect of new digital infrastructure is more significant. This study provides empirical evidence and policy references for promoting and amplifying the green growth effects of new digital infrastructure

Unstructured road extraction and roadside fruit recognition in grape orchards based on a synchronous detection algorithm

Accurate road extraction and recognition of roadside fruit in complex orchard environments are essential prerequisites for robotic fruit picking and walking behavioral decisions. In this study, a novel algorithm was proposed for unstructured road extraction and roadside fruit synchronous recognition, with wine grapes and nonstructural orchards as research objects. Initially, a preprocessing method tailored to field orchards was proposed to reduce the interference of adverse factors in the operating environment. The preprocessing method contained 4 parts: interception of regions of interest, bilateral filter, logarithmic space transformation and image enhancement based on the MSRCR algorithm. Subsequently, the analysis of the enhanced image enabled the optimization of the gray factor, and a road region extraction method based on dual-space fusion was proposed by color channel enhancement and gray factor optimization. Furthermore, the YOLO model suitable for grape cluster recognition in the wild environment was selected, and its parameters were optimized to enhance the recognition performance of the model for randomly distributed grapes. Finally, a fusion recognition framework was innovatively established, wherein the road extraction result was taken as input, and the optimized parameter YOLO model was utilized to identify roadside fruits, thus realizing synchronous road extraction and roadside fruit detection. Experimental results demonstrated that the proposed method based on the pretreatment could reduce the impact of interfering factors in complex orchard environments and enhance the quality of road extraction. Using the optimized YOLOv7 model, the precision, recall, mAP, and F1-score for roadside fruit cluster detection were 88.9%, 89.7%, 93.4%, and 89.3%, respectively, all of which were higher than those of the YOLOv5 model and were more suitable for roadside grape recognition. Compared to the identification results obtained by the grape detection algorithm alone, the proposed synchronous algorithm increased the number of fruit identifications by 23.84% and the detection speed by 14.33%. This research enhanced the perception ability of robots and provided a solid support for behavioral decision systems

Mechanical response analysis of surrounding rock bearing structure of soft rock roadway based on full-length anchorage

A mechanical model of full-length anchoring bolt is established to study the stability of mechanical bearing structure of surrounding rock in high stress soft rock roadway after full-length anchoring bolt. The model considers the dilatancy characteristics of soft rock post-peak strength softening and the stress boundary conditions of full-length bolt, and the analytical formula of bolt stress is derived. Furthermore, the mechanical model of full-length anchored surrounding rock is established by equivalent the anchoring force to the form of volume force. From shallow to deep, it is divided into anchorage residual zone, anchorage plastic softening zone, non-anchorage plastic softening zone and elastic zone, and the stress expression of each zone is deduced. Combined with engineering examples, the influence of space effect, expansion coefficient, bolt length and tray reaction force on surrounding rock stress and bolt stress is analyzed. The results show that under the influence of spatial effect, the deformation and failure of roadway presents progressive development. The concept of ' anchorage control zone ' is proposed, that is, in the process of full-length bolt support, the virtual support force and anchoring force of surrounding rock are in a state of reciprocal growth and decline, thus inhibiting the transfer of surrounding rock stress to the deep and effectively reducing the plastic zone. The earlier the anchor bolt is installed, the greater the deformation of the surrounding rock acting on the rod body, and the easier it is to form a common bearing body with the surrounding rock. The axial force of the anchor bolt is proportional to the expansion coefficient. With the increase of the expansion coefficient, the growth rate of the anchoring force is significantly accelerated, which ensures the recovery effect of the anchor bolt on the radial stress of the surrounding rock. The axial force distribution and peak value of the rod body will increase with the increase of the length of the bolt and the bonding range of the surrounding rock/anchoring agent interface, and then the peak area of the tangential stress of the surrounding rock will shift to the direction of the tunnel wall. The effect of the reaction force of the full-length bolt tray is mainly reflected in improving the stress of the bolt, giving full play to the anchoring effect of the bolt and the ability to protect the surface, and having little effect on the boundary of the residual zone and the plastic zone

Probiotic Limosilactobacillus reuteri DSM 17938 Changes Foxp3 Deficiency-Induced Dyslipidemia and Chronic Hepatitis in Mice

The probiotic Limosilactobacillus reuteri DSM 17938 produces anti-inflammatory effects in scurfy (SF) mice, a model characterized by immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (called IPEX syndrome in humans), caused by regulatory T cell (Treg) deficiency and is due to a Foxp3 gene mutation. Considering the pivotal role of lipids in autoimmune inflammatory processes, we investigated alterations in the relative abundance of lipid profiles in SF mice (± treatment with DSM 17938) compared to normal WT mice. We also examined the correlation between plasma lipids and gut microbiota and circulating inflammatory markers. We noted a significant upregulation of plasma lipids associated with autoimmune disease in SF mice, many of which were downregulated by DSM 17938. The upregulated lipids in SF mice demonstrated a significant correlation with gut bacteria known to be implicated in the pathogenesis of various autoimmune diseases. Chronic hepatitis in SF livers responded to DSM 17938 treatment with a reduction in hepatic inflammation. Altered gene expression associated with lipid metabolism and the positive correlation between lipids and inflammatory cytokines together suggest that autoimmunity leads to dyslipidemia with impaired fatty acid oxidation in SF mice. Probiotics are presumed to contribute to the reduction of lipids by reducing inflammatory pathways