First Report on the Occurrence and Antibiotic Resistance Profile of Colistin-Resistant Escherichia coli in Raw Beef and Cow Feces in Vietnam.

Colistin-resistant Escherichia coli (COE) has been recently recognized as a serious threat to animal and human health. This study aimed to determine the prevalence and antibiotic resistance profile of COE isolated from raw beef and cow feces in Vietnam. Our results showed that 16% (16/100) and 32% (32/100) of raw beef and cow feces samples were positive for COE, respectively. A total of 48 COE strains were isolated, with 16 originating from raw beef and 32 from cow feces samples. The antibiotic susceptibility test revealed that the COE isolates were highly resistant to ampicillin, tetracycline, florfenicol, trimethoprim/sulfamethoxazole, streptomycin, and nalidixic acid, with resistance rates ranging from 66.67% to 87.5%. In addition, 87.5% of the isolates were identified to be multidrug-resistant strains. Further molecular characterization indicated that all COE isolates carried the mcr-1 gene, with 16 of them also harboring blaCTX-M-55 genes. Taken together, the findings in this study demonstrate that raw beef and cow feces are important sources of COE, which can be potentially transmitted to humans through the food chain.

Stress Wave Propagation in a Rayleigh-Love Rod with Sudden Cross-Sectional Area Variations Impacted by a Striker Rod.

This paper presents an in-depth study of the stress wave behavior propagating in a Rayleigh-Love rod with sudden cross-sectional area variations. The analytical solutions of stress waves are derived for the reflection and transmission propagation behavior at the interface of the cross-sectional area change in the rod, considering inertia and Poisson's effects on the rod material. Examples solved using the finite element method are provided to verify the correctness of the analytical results. Based on the forward analysis of Rayleigh-Love wave propagation in a rod impacted by a striker rod, an impact-echo-type nondestructive testing (NDT) method is proposed to conduct defect assessment in rod-type structural components with sudden cross-sectional area changes within a cover medium. This proposed NDT method can identify the location, extension, and cross-sectional area drop ratios of an irregular zone in the rod to be inspected.

Prevalence, Molecular Characterization, and Antimicrobial Resistance Profiles of Shiga Toxin-Producing Escherichia coli Isolated from Raw Beef, Pork, and Chicken Meat in Vietnam.

Shiga toxin-producing Escherichia coli (STEC) is one of the most important foodborne pathogens, and the rise of antibiotic resistance to it is a significant threat to global public health. The purpose of this study is to investigate the prevalence, molecular characterization, and antibiotic resistance of STEC isolated from raw meat in Vietnam. The findings in this study showed that the prevalence of STEC in raw beef, pork, and chicken meat was 9.72% (7/72), 5.56% (4/72), and 1.39% (1/72), respectively. The STEC isolates were highly resistant to ampicillin (91.67%) and tetracycline (91.67%), followed by trimethoprim/sulfamethoxazole (83.33%), streptomycin (75%), and florfenicol (66.67%). The incidence of STEC virulence-associated genes, including stx1, stx2, eae, and ehxA, was 8.33% (1/12), 91.67% (11/12), 33.33% (4/12), and 58.33% (7/12), respectively. STEC serogroups O157, O26, and O111 were detected in 3 out of 12 STEC isolates. Two isolates were found to be ESBL producers carrying the blaCTX-M-55 gene, and three isolates were colistin-resistant strains harboring the mcr-1 gene. Notably, a STEC O111 isolate from chicken meat harbored both the blaCTX-M-55 and mcr-1 genes.

Synthesis and crystal structures of three organoplatinum(II) complexes bearing natural aryl-olefin and quinoline derivatives.

Three organoplatinum(II) complexes bearing natural aryl-olefin and quinoline derivatives, namely, [4-meth-oxy-5-(2-meth-oxy-2-oxoeth-oxy)-2-(prop-2-en-1-yl)phen-yl](quinolin-8-olato)platinum(II), [Pt(C13H15O4)(C9H6NO)], (I), [4-meth-oxy-5-(2-oxo-2-propoxyeth-oxy)-2-(prop-2-en-1-yl)phen-yl](quinoline-2-carboxy-l-ato)platinum(II), [Pt(C15H19O4)(C10H6NO2)], (II), and chlorido-[4-meth-oxy-5-(2-oxo-2-propoxyeth-oxy)-2-(prop-2-en-1-yl)phen-yl](quinoline)-plat-inum(II), [Pt(C15H19O4)Cl(C9H7N)], (III), were synthesized and structurally characterized by IR and 1H NMR spectroscopy, and by single-crystal X-ray diffraction. The results showed that the cyclo-platinated aryl-olefin coordinates with PtII via the carbon atom of the phenyl ring and the C=Colefinic group. The deprotonated 8-hy-droxy-quinoline (C9H6NO) and quinoline-2-carb-oxy-lic acid (C10H6NO2) coordinate with the PtII atom via the N and O atoms in complexes (I) and (II) while the quinoline (C9H7N) coordinates via the N atom in (III). Moreover, the coordinating N atom in complexes (I)-(III) is in the cis position compared to the C=Colefinic group. The crystal packing is characterized by C-H⋯π, C-H⋯O [for (II) and (III)], C-H⋯Cl [for (III) and π-π [for (I)] inter-actions.

Antibiotic Resistance Profile and Bio-Control of Multidrug-Resistant Escherichia coli Isolated from Raw Milk in Vietnam Using Bacteriophages.

E. coli is an important zoonotic pathogen capable of causing foodborne illness and bovine mastitis. Bacteriophages have been increasingly considered a promising tool to control unwanted bacteria. The aim of this study is to determine the antibiotic resistance profile of E. coli isolated from raw milk and the efficacy of phage in controlling multidrug-resistant E. coli in raw milk. Antibiotic susceptibility testing showed the highest resistance rates of E. coli isolates to co-trime (27.34%) and ampicillin (27.34%), followed by streptomycin (25.18%), tetracycline (23.02%), and the lowest resistance rates to ciprofloxacin, gentamycin, and ceftazidime, all at a rate of 2.16%. All isolates were susceptible to meropenem. Of the 139 E. coli isolates, 57 (41.01%) were resistant to at least one antibiotic, and 35 (25.18%) were classified as MDR strains. Molecular characterization indicated that 5 (3.6%) out of the 139 isolates were STEC strains carrying stx1 gene. Seven (5.04%) isolates were phenotypically identified as ESBLEC, and four isolates (2.88%) were resistant to colistin. The results of the genotypic test revealed that four out of seven ESBLEC strains carried both blaTEM and blaCTX-M-1, two harbored blaTEM, and one possessed blaCTX-M-1, while mcr-1 was detected in all four colistin-resistant E. coli isolates. In particular, one isolated E. coli strain (EM148) was determined to be a multidrug-resistant strain simultaneously carrying blaTEM, blaCTX-M-1, and mcr-1. A total of eight phages were successfully recovered from raw milk. The application of phage PEM3 significantly reduced viable counts of multidrug-resistant host EM148 in raw milk by at least 2.31 log CFU/mL at both 24 °C and 4 °C.

Comparing the accuracy of two machine learning models in detection and classification of periapical lesions using periapical radiographs.

BACKGROUND: Previous deep learning-based studies were mainly conducted on detecting periapical lesions; limited information in classification, such as the periapical index (PAI) scoring system, is available. The study aimed to apply two deep learning models, Faster R-CNN and YOLOv4, in detecting and classifying periapical lesions using the PAI score from periapical radiographs (PR) in three different regions of the dental arch: anterior teeth, premolars, and molars. METHODS: Out of 2658 PR selected for the study, 2122 PR were used for training, 268 PR were used for validation and 268 PR were used for testing. The diagnosis made by experienced dentists was used as the reference diagnosis. RESULTS: The Faster R-CNN and YOLOv4 models obtained great sensitivity, specificity, accuracy, and precision for detecting periapical lesions. No clear difference in the performance of both models among these three regions was found. The true prediction of Faster R-CNN was 89%, 83.01% and 91.84% for PAI 3, PAI 4 and PAI 5 lesions, respectively. The corresponding values of YOLOv4 were 68.06%, 50.94%, and 65.31%. CONCLUSIONS: Our study demonstrated the potential of YOLOv4 and Faster R-CNN models for detecting and classifying periapical lesions based on the PAI scoring system using periapical radiographs.

Temozolomide promotes matrix metalloproteinase 9 expression through p38 MAPK and JNK pathways in glioblastoma cells.

Glioblastoma (GBM) is a highly aggressive and deadly brain cancer. Temozolomide (TMZ) is the standard chemotherapeutic agent for GBM, but the majority of patients experience recurrence and invasion of tumor cells. We investigated whether TMZ treatment of GBM cells regulates matrix metalloproteinases (MMPs), which have the main function to promote tumor cell invasion. TMZ effectively killed GL261, U343, and U87MG cells at a concentration of 500 µM, and surviving cells upregulated MMP9 expression and its activity but not those of MMP2. TMZ also elevated levels of MMP9 mRNA and MMP9 promoter activity. Subcutaneous graft tumors survived from TMZ treatment also exhibited increased expression of MMP9 and enhanced gelatinolytic activity. TMZ-mediated MMP9 upregulation was specifically mediated through the phosphorylation of p38 and JNK. This then stimulates AP-1 activity through the upregulation of c-Fos and c-Jun. Inhibition of the p38, JNK, or both pathways counteracted the TMZ-induced upregulation of MMP9 and AP-1. This study proposes a potential adverse effect of TMZ treatment for GBM: upregulation of MMP9 expression potentially associated with increased invasion and poor prognosis. This study also provides valuable insights into the molecular mechanisms by which TMZ treatment leads to increased MMP9 expression in GBM cells.

Prevalence and Antibiotic Resistance Profile of Clostridium perfringens Isolated from Pork and Chicken Meat in Vietnam.

Clostridium perfringens is one of the most important zoonotic pathogens as it can cause food poisoning in humans and necrotic enteritis in both animals and humans. Meat, especially pork and chicken meat, is considered the main vehicle for the transmission of C. perfringens from animals to humans. The purpose of this study was to determine the prevalence, toxinotype, and antimicrobial resistance profile of C. perfringens isolated from pork and chicken meat sold in Vietnam. The isolation results showed that 15/50 (30%) of pork samples and 8/50 (16%) of chicken meat samples were contaminated with C. perfringens. The isolates exhibited their highest resistance rate to tetracycline (21/23; 91.30%) and clindamycin (10/23; 43.48%). On the contrary, their lowest resistance rates were observed in response to imipenem (2/23; 8.70%) and cefoxitin (1/23; 4.35%). In particular, 34.78% (8/23) of C. perfringens isolates were identified to be multidrug-resistant strains. The results of toxin genotyping indicated that all isolates were positive for the cpa gene and belonged to type A.

Employer branding, organization's image and reputation, and intention to apply: the moderating role of the availability of organizational information on social media.

The topics of employer branding and organization's image and reputation have been well-researched in the literature. However, most empirical studies were conducted in Europe, Australia, or the United States, but very few were conducted in Asia, especially in Vietnam. In addition, the interaction of image and reputation with the availability of information on social media is poorly understood. Using signaling theory for building a research model, we collected data from 206 Generation Z respondents from the logistics sector in Vietnam. Our findings show that (i) employer branding has positively and significantly related to an organization's image and reputation; (ii) the organization's image and reputation had a significant effect on job seekers' intention to apply; and (iii) the interaction of image and reputation with availability of information on social media to predict the job seeker's intention to apply. The paper also presented implications for both researchers and practitioners as well as recommendations for future research.

Constructing B─N─P Bonds in Ultrathin Holey g-C3N4 for Regulating the Local Chemical Environment in Photocatalytic CO2 Reduction to CO.

The lack of intrinsic active sites for photocatalytic CO2 reduction reaction (CO2RR) and fast recombination rate of charge carriers are the main obstacles to achieving high photocatalytic activity. In this work, a novel phosphorus and boron binary-doped graphitic carbon nitride, highly porous material that exhibits powerful photocatalytic CO2 reduction activity, specifically toward selective CO generation, is disclosed. The coexistence of Lewis-acidic and Lewis-basic sites plays a key role in tuning the electronic structure, promoting charge distribution, extending light-harvesting ability, and promoting dissociation of excitons into active carriers. Porosity and dual dopants create local chemical environments that activate the pyridinic nitrogen atom between the phosphorus and boron atoms on the exposed surface, enabling it to function as an active site for CO2RR. The P-N-B triad is found to lower the activation barrier for reduction of CO2 by stabilizing the COOH reaction intermediate and altering the rate-determining step. As a result, CO yield increased to 22.45 µmol g-1 h-1 under visible light irradiation, which is ≈12 times larger than that of pristine graphitic carbon nitride. This study provides insights into the mechanism of charge carrier dynamics and active site determination, contributing to the understanding of the photocatalytic CO2RR mechanism.

Reference Value Fibrin Monomer in Healthy Children: A Cross-Sectional Study.

The objective of this study is to determine the fibrin monomer reference intervals in healthy children. This cross-sectional study was conducted in the Hematology Department at Vietnam National Children's Hospital (April 2023 to March 2024). Children without prior history of clotting disorders or anticoagulants use hospitalized in preparation for orthopedic surgery or inguinal hernia surgery were enrolled in the study. The fibrin monomer test method was the quantitative fibrin monomer test on the STA-R system (Diagnostica Stago™, France). Eighty-six children (58 males and 28 females) were enrolled in the study. The median (interquartile range, 2.5th-97.5th) fibrin monomer value of the study subjects was 2.56 (0.11-5.93) µg/mL, with no statistically significant difference in fibrin monomer values among the age groups of 1 month to 3 years, 3 years to 13 years, and 13 years to 18 years. This is the first study conducted in Vietnam to determine reference values of fibrin monomer in children. This information can help in the diagnosis and treatment of early hypercoagulation stage and disseminated intravascular coagulation in children.

Identification of novel phenylalanine derivatives bearing a hydroxamic acid moiety as potent quorum sensing inhibitors.

Phenylalanine derivatives are a well-known small moiety responsible for controlling the virulence factors of several bacteria. Herein, for the first time, we report novel structures of phenylalanine derivatives bearing a hydroxamic acid moiety which were designed, synthesized, and evaluated for use as quorum sensing inhibitors. Biological results reveal that six compounds showed good quorum sensing inhibitors properties with an IC50 ranging from 7.12 ± 2.11 µM-92.34 ± 2.09 µM (4NPO, a reference compound, IC50 = 29.13 ± 0.88 µM). In addition, three out of the six compounds (4a, 4c, 4h) showed strong anti-biofilm formation and CviR inhibitory activity when compared to that of 4NPO. These biological data were also confirmed by computational studies. In this series of compounds, 4h is the most promising compound for future drug development targeting quorum sensing. Our results concluded that the fragment-based drug design is a good approach for the discovery of novel quorum-sensing inhibitors in the future.

A facile paper-based chromatography coupled Au nanodendrite on nickel foam for application in separation and SERS measurement.

A simple paper-based chromatography coupling with nickel foam decorated Au nanodendrite (PP-AuND/NiF) was fabricated for simultaneous separation and surface-enhanced Raman scattering (SERS) detection of Rhodamine-6G (R6G) from a mixture of analytes. The three-dimensional porous nickel foam (NiF) was employed as a sampling diffusion platform, and AuND with a high surface active area beneficial for SERS efficiency was electro-deposited directly onto the NiF frame. The structure of AuND/NiF was characterized by X-ray diffraction and scanning electron microscopy. The AuND/NiF could detect R6G at 0.1 nM, and the enhancement factor was 1.84 x 106. The AuND/NiF was durable, with a slight signal decrease after 6 m of drop-testing. Also, upon three days of exposure to ambient air, the signal droped only 3.35 %. Subsequently, the PP-AuND/NiF was constructed by directly situating AuND/NiF on a paper strip, serving as a sample in and out to AuND/NiF. A mixture of two SERS active compounds, namely 2-Naphthalenethiol (2-NpSH) and Rhodamine 6G (R6G), was prepared in ethanol: water (1:1) solution to evaluate PP-AuND/NiF separation capability. Raman measurements along different distances of AuND/NiF were performed, and the signal of 2-NpSH was dismissed after 3.0 mm, while R6G's signals were observed throughout AuND/NiF. In general, the PP-AuND/NiF demonstrated effective separation and SERS measurement of analytes in a mixture, which could be applicable for more complex samples in the future, especially in clinical analysis.

Valorization of the treatment of antibiotic and organic contents generated from an in-situ-RAS-like shrimp farming pond by using graphene-quantum-dots deposited graphitic carbon nitride photocatalysts.

In this study, we investigated the possibility of a photocatalytic system that uses graphene-quantum-dot (GQD)-deposited graphitic carbon nitride (g-C3N4) to treat tetracycline (TC) and other organic compounds generated from an in-situ-recirculatory-aquaculture-system (RAS)-like shrimp farming pond. GQDs were successfully deposited on the exfoliated g-C3N4 base through a hydrothermal treatment. The results showed that the incorporation of GQDs into the g-C3N4 enhanced its porosity without aggregating its mesoporous structure. The GQDs-deposited g-C3N4 photocatalysts revealed sheet-like structures with nanopores on their surface that facilitate photocatalysis. More than 90% of the TC was removed by the photocatalysts under UV-LED irradiation. Low loadings of GQDs over g-C3N4 resulted in a faster and more effective photocatalysis of TC, mainly driven by.O2- radicals. The photocatalysts were also applicable in the degradation of organic compounds with 27% of the total organic compounds (TOC) being removed from the wastewater of a RAS-like shrimp farming pond.

Maternal and perinatal outcomes of hypertensive disorders in pregnancy: Insights from the National Hospital of Obstetrics and Gynecology in Vietnam.

INTRODUCTION: Hypertension is the common disorder encountered during pregnancy, complicating 5% to 10% of all pregnancies. Hypertensive disorders in pregnancy (HDP) are also a leading cause of maternal and perinatal morbidity and mortality. The majority of feto-maternal complications due to HPD have occurred in the low- and middle-income countries. However, few studies have been done to assess the feto-maternal outcomes and the predictors of adverse perinatal outcome among women with HDP in these countries. METHODS: A prospective cohort study was conducted on women with HDP who were delivered at National Hospital of Obstetrics and Gynecology, Vietnam from March 2023 to July 2023. Socio-demographic and obstetrics characteristics, and feto-maternal outcomes were obtained by trained study staff from interviews and medical records. Statistical analysis was performed using SPSS version 26.0. Bivariate and multiple logistic regressions were done to determine factors associated with adverse perinatal outcome. A 95% confidence interval not including 1 was considered statically significant. RESULTS: A total of 255 women with HDP were enrolled. Regarding adverse maternal outcomes, HELLP syndrome (3.9%), placental abruption (1.6%), and eclampsia (1.2%) were three most common complications. There was no maternal death associated with HDP. The most common perinatal complication was preterm delivery developed in 160 (62.7%) of neonates. Eight stillbirths (3.1%) were recorded whereas the perinatal mortality was 6.3%. On bivariate logistic regression, variables such as residence, type of HDP, highest systolic BP, highest diastolic BP, platelet count, severity symptoms, and birth weight were found to be associated with adverse perinatal outcome. On multiple logistic regression, highest diastolic BP, severity symptoms, and birth weight were found to be independent predictors of adverse perinatal outcome. CONCLUSION: Our study showed lower prevalence of stillbirth, perinatal mortality, and maternal complication compared to some previous studies. Regular antenatal care and early detection of abnormal signs during pregnancy help to devise an appropriate monitoring and treatment strategies for each women with HDP.

INO80 function is required for mouse mammary gland development, but mutation alone may be insufficient for breast cancer.

The aberrant function of ATP-dependent chromatin remodeler INO80 has been implicated in multiple types of cancers by altering chromatin architecture and gene expression; however, the underlying mechanism of the functional involvement of INO80 mutation in cancer etiology, especially in breast cancer, remains unclear. In the present study, we have performed a weighted gene co-expression network analysis (WCGNA) to investigate links between INO80 expression and breast cancer sub-classification and progression. Our analysis revealed that INO80 repression is associated with differential responsiveness of estrogen receptors (ERs) depending upon breast cancer subtype, ER networks, and increased risk of breast carcinogenesis. To determine whether INO80 loss induces breast tumors, a conditional INO80-knockout (INO80 cKO) mouse model was generated using the Cre-loxP system. Phenotypic characterization revealed that INO80 cKO led to reduced branching and length of the mammary ducts at all stages. However, the INO80 cKO mouse model had unaltered lumen morphology and failed to spontaneously induce tumorigenesis in mammary gland tissue. Therefore, our study suggests that the aberrant function of INO80 is potentially associated with breast cancer by modulating gene expression. INO80 mutation alone is insufficient for breast tumorigenesis.

A Cell-Adapted Live-Attenuated Vaccine Candidate Protects Pigs against the Homologous Strain VNUA-ASFV-05L1, a Representative Strain of the Contemporary Pandemic African Swine Fever Virus.

African swine fever (ASF) is a lethal and highly contagious transboundary animal disease with the potential for rapid international spread. Currently, there is no ASF vaccine commercially available. All infected animals must be isolated and culled immediately upon the confirmation of the presence of the virus. Studies leading to the rational development of protective ASF vaccines are urgently needed. Here, we generated a safe and efficacious live-attenuated vaccine (LAV) VNUA-ASFV-LAVL2 by serially passaging a field isolate (VNUA-ASFV-05L1, genotype II) in porcine alveolar macrophages (PAMs, 65 passages) and an immortalized porcine alveolar macrophage cell line (3D4/21, 55 passages). VNUA-ASFV-LAVL2 can efficiently replicate in both PAMs and 3D4/21 cells. It provides 100% protection, even with the low dose of 102 HAD50, to the vaccinated pigs against the challenge of contemporary pandemic ASFV field isolate. Pigs vaccinated with this LAV in a dose range of 102 to 105 HAD50 remained clinically healthy during both the 28-day observation period of immunization and the 28-day observation period of challenge. VNUA-ASFV-LAVL2 was eliminated from blood by 28 days post-inoculation (DPI), and from feces or oral fluids by 17 DPI. Although the vaccine strain in serum remained a safe and attenuated phenotype after five passages in swine, a reversion-to-virulence study using blood or tissue homogenates at peak viremia will be conducted in the future. ASFV-specific IgG antibodies and significant cellular immunity were detected in vaccinated pigs before the ASFV challenge. These results indicate that the VNUA-ASFV-LAVL2 strain is a safe and efficacious LAV against the genotype II ASFV strain responsible for current ASF outbreaks in Asia.

Determination of Methanol, Acetaldehyde, and Ethyl Acetate in Thousand Folds of Ethanol Sample by Headspace Gas Chromatography with Mass Spectrometry.

Alcohol beverages have been widely consumed in several parts of the world. In this study, volatile organic compounds in alcoholic beverages including acetaldehyde, ethyl acetate, methanol, and higher ethanol were investigated and evaluated using a headspace gas chromatograph equipped with a mass spectrometer. This study evaluated the suitability of the chromatographic system, linearity, limit of detection, and limit of quantification, accuracy, and precision of the single and simultaneous determination of acetaldehyde, ethyl acetate, and methanol in thousand folds of ethanol. Results showed that the acetaldehyde concentration in local beer samples and local manual product liqueur samples ranged from 4.65 to 13.22 mg/L and from 5.55 to 75.96 mg/L, respectively, but in local industrial product liqueur samples, acetaldehyde was not detected. Methanol was only detected in a few local beer samples and locally manually produced liqueur samples within low concentrations. Ethyl acetate was only detected in all local beer samples, but it was not present in local industrial product liqueur samples.

Polymer-Based Hydrogels Applied in Drug Delivery: An Overview.

Polymer-based hydrogels are hydrophilic polymer networks with crosslinks widely applied for drug delivery applications because of their ability to hold large amounts of water and biological fluids and control drug release based on their unique physicochemical properties and biocompatibility. Current trends in the development of hydrogel drug delivery systems involve the release of drugs in response to specific triggers such as pH, temperature, or enzymes for targeted drug delivery and to reduce the potential for systemic toxicity. In addition, developing injectable hydrogel formulations that are easily used and sustain drug release during this extended time is a growing interest. Another emerging trend in hydrogel drug delivery is the synthesis of nano hydrogels and other functional substances for improving targeted drug loading and release efficacy. Following these development trends, advanced hydrogels possessing mechanically improved properties, controlled release rates, and biocompatibility is developing as a focus of the field. More complex drug delivery systems such as multi-drug delivery and combination therapies will be developed based on these advancements. In addition, polymer-based hydrogels are gaining increasing attention in personalized medicine because of their ability to be tailored to a specific patient, for example, drug release rates, drug combinations, target-specific drug delivery, improvement of disease treatment effectiveness, and healthcare cost reduction. Overall, hydrogel application is advancing rapidly, towards more efficient and effective drug delivery systems in the future.

A novel n-p heterojunction Bi2S3/ZnCo2O4 photocatalyst for boosting visible-light-driven photocatalytic performance toward indigo carmine.

An innovative p-n heterojunction Bi2S3/ZnCo2O4 composite was first fabricated via a two-step co-precipitation and hydrothermal method. By controlling the weight amount of Na2S and Bi(NO3)3 precursor, different heterogeneous xBi2S3/ZnCo2O4 were synthesized (x = 0, 2, 6, 12, and 20). The p-n heterojunction Bi2S3/ZnCo2O4 was characterized by structural, optical, and photochemical properties and the photocatalyst decoloration of indigo carmine. Mott-Schottky plots proved a heterojunction formed between n-Bi2S3 and p-ZnCo2O4. Furthermore, the investigation of the photocurrent response indicated that the Bi2S3/ZnCo2O4 composite displayed an enhanced response, which was respectively 4.6 and 7.3 times (4.76 µA cm-2) greater than that of the pure Bi2S3 (1.02 µA cm-2) and ZnCo2O4 (0.65 µA cm-2). Especially the optimized p-n Bi2S3/ZnCo2O4 heterojunction with 12 wt% Bi2S3 showed the highest photocatalyst efficacy of 92.1% at 40 mg L-1 solutions, a loading of 1.0 g L-1, and a pH of 6 within 90 min of visible light illumination. These studies prove that p-n Bi2S3/ZnCo2O4 heterojunction photocatalysts can greatly boost their photocatalytic performance because the inner electric field enhances the process of separating photogenerated electron-hole pairs. Furthermore, this composite catalyst showed good stability and recyclability for environmental remediation.