bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability analysis method of competitive failure processes considering the coupling effect of multiple shock processes and degradation process
Authors: Bai Xiaoning , Li Yonghua , Gong Qi , Wang Denglong , Hu Chaoqun
Published: March 2024

During the operational phase, complex systems are subject to various shocks, both random and continuous degradation. This coupling effect poses significant challenges for reliability assessment. The proposed method aims to provide a clear and objective evaluation of the system's reliability. In this paper, we propose a competitive failure reliability analysis method that considers the coupling effect of multiple shock processes and degradation processes. The random shocks are subdivided into external and internal shocks. The degradation increment is mainly influenced by external shocks, whereas internal shocks affect the degradation rate. The combined effect of these two shock processes accelerates the failure processes. Additionally, two different shock models are combined to create an extreme‐cumulative shock model to assess the impact of various shock processes and the degradation process on system reliability. The analysis examines the coupling effect between the degradation process and shock processes to explore the influence law between hard failure and soft failure. Subsequently, the reliability modeling of competitive failure processes is completed. Finally, practical case studies demonstrate the effectiveness and practicality of the proposed method.
Quantum K‐Nearest Neighbor Classification Algorithm via a Divide‐and‐Conquer Strategy
Authors: Gong Li‐Hua , Ding Wei , Li Zi , Wang Yuan‐Zhi , Zhou Nan‐Run
Published: March 2024

The K‐nearest neighbor algorithm is one of the most frequently applied supervised machine learning algorithms. Similarity computing is considered to be the most crucial and time‐consuming step among the classical K‐nearest neighbor algorithm. A quantum K‐nearest neighbor algorithm is proposed based on the divide‐and‐conquer strategy. A quantum circuit is designed to calculate the fidelity between the test sample and each feature vector of the training dataset. The quantum K‐nearest neighbor algorithm has higher classification efficiency in high‐dimensional data processing. The classification accuracy of the proposed algorithm is equivalent to that of the classical K‐nearest neighbor algorithm under the IRIS dataset. In addition, compared with the typical quantum K‐nearest neighbor algorithms, the proposed classification method possesses higher classification accuracy with less calculation time, which has wide applications in the industrial field.
Preliminary investigation on the analysis of the whole components of Pogejiuxin decoction and its formulation pattern based on ultrahigh‐performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry
Authors: Zhang Qi , Xiang Jun , Fan Qian , Wu Pingping , Wang Qian , Xiao Xiji , Wu Aizhi , Rong Li , Wang Yumei , Zhang Cuixian
Published: March 2024

Rational

Pogejiuxin decoction (PGJXD) is one of the most important formulas for the treatment of heart failure. However, there is a great lack of research on the material basis of this formula, especially research on its compatibility laws, which restricts its clinical use. Studying the complete ingredients and compatibility rules of PGJXD has great significance for guiding clinical medication.

Methods

The entire formula, the major single herbs, the drug pairs and the disassembled formula were analyzed by ultrahigh‐performance liquid chromatography with quadrupole time‐of‐flight mass spectrometry (UHPLC/QTOFMS/MS), matching the chemical composition database and global natural product social molecular networking to explain the chemical composition as well as the combination pattern of PGJXD.

Results

A total of 1048 chemical constituents were fully analyzed from the major single herbs, the drug pairs and the disassembled formula and 188 chemical constituents, including 13 potential novel compounds, were firstly identified from the whole formula. We found that the chemical compositions were reduced after the single herbs were matched to the other herbs, especially the significant reduction of highly toxic diester alkaloids after compatibility, indicating that the medicines of PGJXD were interdependent and controlled by each other.

Conclusion

This study innovatively researches and compares the compositional differences between the entire formula of PGJXD, the single, paired and separated formulas, greatly extending our understanding of the chemical substance basis of these compounds, and preliminarily explores the compatibility laws of PGJXD, providing some theoretical guidance for clinical medication.
Metabolomic and microbiome analysis of cervicovaginal mucus in in vitro fertilization–embryo transfer: Toward predicting pregnancy success
Authors: Nishio Eiji , Iwata Aya , Kawasaki Rie , Kukimoto Iwao , Nishizawa Haruki , Fujii Takuma
Published: March 2024

Purpose

In the context of in vitro fertilization–embryo transfer (IVF–ET), factors other than egg quality may be key determinants of treatment success, in particular, maternal factors related to uterine endometrial receptivity and unidentified factors. We therefore aimed to analyze the metabolome and microbiome in IVF–ET patients who did and did not achieve pregnancy.

Methods

Cervicovaginal mucus was collected from patients undergoing IVF–ET. Metabolite analysis was conducted by liquid chromatography‐mass spectrometry and the microbiota were determined by the polymerase chain reaction using universal 16S‐rRNA gene bacterial primers by MiSeq sequencing. Patients were classified as pregnant (N = 10) or nonpregnant (N = 13). Metabolic pathways were examined by MetaboAnalyst.

Results

Three metabolic pathways, including alanine‐aspartate–glutamate metabolism, arginine biosynthesis, and cysteine‐methionine metabolism, were commonly decreased at the time of embryo transfer irrespective pregnant outcomes. Notably, pyruvate was decreased in the pregnant group. Amino acid metabolites showed inverse correlations with the presence of anaerobic microbiota in the nonpregnant group.

Conclusions

Metabolism decreased during embryo transplantation, with a notable decrease in pyruvate metabolism, particularly in patients who became pregnant. The behavior of metabolites in the pregnant and nonpregnant groups suggests that metabolome analysis in the cervicovaginal mucus may be a diagnostic marker for predicting pregnancy.
A Deep Dive into Cu2ZnSnS4 (CZTS) Solar Cells: A Review of Exploring Roadblocks, Breakthroughs, and Shaping the Future
Authors: Shah Usman Ali , Wang Ao , Irfan Ullah Muhammad , Ishaq Muhammad , Shah Imtiaz Alam , Zeng Yiyu , Abbasi Misbah Sehar , Umair Muhammad Ali , Farooq Umar , Liang Guang‐Xing , Sun Kaiwen
Published: March 2024

Renewable energy is crucial for sustainable future, and Cu2ZnSnS4 (CZTS) based solar cells shine as a beacon of hope. CZTS, composed of abundant, low‐cost, and non‐toxic elements, shares similarities with Cu(In,Ga)Se2 (CIGS). However, despite its promise and appealing properties for solar cells, CZTS‐based solar cells faces performance challenges owing to inherent issues with CZTS material, and conventional substrate structure complexities. This review critically examines these roadblocks, explores ongoing efforts and breakthroughs, providing insight into the evolving landscape of CZTS‐based solar cells research. Furthermore, as an optimistic turn in the field, the review first highlights the crucial need to transition to a superstrate structure for CZTS‐based single junction devices, and summarizes the substantial progress made in this direction. Subsequently, dive into the discussion about the fascinating realm of CZTS‐based tandem devices, providing an overview of the existing literature as well as outlining the possible potential strategies for enhancing the efficiency of such devices. Finally, the review provides a useful outlook that outlines the priorities for future research and suggesting where efforts should concentrate to shape the future of CZTS‐based solar cells.
Valorization of waste coffee silverskin as a source of antioxidant by extraction with agitation
Authors: Kulkarni Rajeswari M. , Mentha Spandana Samyukthalakshmi , R Aishwarya , Mascarenhas Errol Winston , Polavarapu Sanjana , Appaiah Takshak
Published: March 2024

Coffee is the second most traded commodity after petrol. The coffee industry produces about 23 million tonnes of waste every year. This implies that the unutilized portion of coffee carries a broad economic and environmental burden. The unutilized portion of coffee includes pulp, mucilage, parchment, husk, silver skin, and spent coffee grounds, each of which has its innate capacity to be reused for various industrial and domestic purposes. Coffee silverskin represents about 4.2% (w/w) of the coffee bean. Moreover, coffee silverskin contains phenolic compounds which have been studied extensively on account of their antioxidant properties. The main aim of the research is to convert coffee silver skin which is discarded as waste in coffee production, into a source of antioxidants that has wide application in the cosmetic and skincare industry. In this paper, conventional extraction methods for varying extraction temperatures (30–70°C), various solvents (n‐hexane, ethyl acetate, acetone, and ethanol) and extraction times (30, 60, and 90 min) were investigated to study their impact on the percentage of the coffee silverskin's antioxidant composition and the antioxidant property along with its total phenolic content (TPC) in coffee silverskin. It was found that ethanol was a suitable solvent and compared to the 50% ethanol‐water mixture, the 90% ethanol‐water mixture showed the highest extraction efficiency at the conditions of 70°C and 60 min for a TPC from coffee silverskin at 213 GAE mg/L.
Advanced analytical techniques for assessing and detecting microplastic pollution in water and wastewater systems
Authors: Özgenç Enes
Published: March 2024

The current study focuses on the sources and formations of microplastics (MPs) in receiving environments, addressing various analytical methods used for the detection and characterization of MPs in water and wastewater, including particle size distribution analysis, FTIR, Raman, SEM‐EDS, thermo analytical methods (Pyro GC‐MS, TGA‐MS, TED‐GC‐MS, TGA‐SPE/TDS‐GC‐MS) and combine techniques (Tagging method, Liquid chromatography, SEM dispersive X‐ray spectrometer). The study fills a gap in the literature by evaluating the advantages and limitations of advanced analytical methods, in addition to commonly used methods like FTIR, Raman, and SEM, providing a perspective on other significant analytical approaches. By examining and comparing different analytical methods used to identify and detect MPs in water and wastewater environments, the research guides scientists in making informed choices when selecting a specific method. A better understanding of these methods will inform future research and facilitate more effective management of potential environmental impacts and human health risks. This study also contributes significantly to preserving water resources, human health, and establishing a sustainable environment by encouraging the generation of actionable information to assess the potential risks of MPs in water and wastewater sources and to develop strategies for reducing their presence.
Identification of rice varieties specialties in Vietnam using Raman spectroscopy
Authors: Giang Le Truong , Trung Pham Quoc , Yen Dao Hai
Published: March 2024

The characteristics and quality of rice are significantly affected by its variety. However, discrimination between varieties is an urgent but difficult and time‐consuming effort in Vietnam. In this study, an effective and reliable identification method was established by Raman spectroscopy (RS). Total Raman spectra of 32 rice samples were acquired from 400 to 1600 cm‐1 and the sensitive fundamental vibrations of less polar groups and bonds in rice were analyzed. Initially, the raw Raman spectra were processed by standard normal variety (SNV) combined with Savitzky Golay (SG) smoothing algorithm. The positive influence of SNV‐SGD2 on the ability to classify rice varieties has been confirmed by principal component analysis (PCA). Next, multivariate analysis methods included PCA, hierarchical cluster analysis (HCA), and K‐nearest neighbor (KNN), that have been compared with each other on the ability to classify rice varieties. All three methods give the ability to classify four rice varieties very well. The PCA method identifies four main factors were starch chains, amylose, amylopectin, and protein contents which are used to distinguish among four rice varieties. While HCA only distinguishes well between rice with high and low amylopectin content and does not provide the main components.
Study on furfural conversion into aromatics over Zn/HZSM‐5 and Fe/HZSM‐5 catalysts
Authors: Van Nam Huynh , Tam Truong Thanh , Tho Van Dinh Son
Published: March 2024

ZSM‐5 zeolite material (Si/Al ratio = 25) was synthesized with silica source of TEOS and TPAOH template. The zeolite is modified into proton form (HZSM‐5) with 343 m2/g of BET surface area, 324 m2/g of micropore area, 0.1491 cm3/g of micropore volume and 5.77 nm of BJH adsorption average pore width. Zinc oxide and iron oxide are dispersed onto HZSM‐5 catalyst surface with different contents by wet impregnation method. The results of HZSM‐5, Zn/HZSM‐5, Fe/HZSM‐5 catalyst materials still retain the micropore structure of ZSM‐5 zeolite. These materials are used as catalysts for furfural pyrolysis in the inert atmosphere (N2) with the temperatures ranged from 400 to 700 °C. The conversion of furfural to aromatic hydrocarbons on catalysts is evaluated by furfural conversion, conversion into aromatics and aromatic hydrocarbons selectivity. Result shows that 3 %Zn/HZSM‐5 and 2 %Fe/HZSM‐5 catalyst favor for furfural pyrolysis at 600 oC. The furfural conversion, the conversion into BTXN and the BTXN selectivity are respectively 48.36 %, 21.18 %, 16.18 % with 3 %Zn/HZSM‐5 catalyst and 64.41 %, 16.47 %, 26.81 % with 2%Fe/HZSM‐5 catalyst. These results are the basic research for the upgrade of pyrolysis oil into fuels.
Determination of organophosphate ester flame retardants in indoor dust and their potential health exposure risk
Authors: Ha Trinh Thu , Cuong Nguyen Duc , Huyen Le Thi , Giang Le Truong
Published: March 2024

This study was conducted to determine organophosphate ester compounds in indoor dust in Hanoi ‐ a populated city in Vietnam. In the study, the concentration and distribution of fifteen organophosphate esters (OPEs) were analyzed in indoor dust specimen. In general, the recorded total concentrations of OPEs in dust ranged from 2.7 to 14.1 μg/g and the average quantities varied from 0.2 to 1.0 μg/g. Particular, 100 % of survey samples were detected signals of OPEs, indeed, tris‐(2‐chloroisopropyl) phosphate (TCPP) and tris(2‐butoxyethyl)phosphate (TBEP) were two of the OPE substances, which their content accounted for the most in 15 analyzed compounds. OPE emission sources in indoor dust could be from locally used wide variety of consumer products and building materials in Hanoi houses. Moreover, tri‐m‐cresyl phosphate (TMCP) was practically observed in survey dust samples, and thus effects of traffic activities on OPEs contamination were not significant. Estimating human exposure to OPEs through directly absorbing foods was implemented and illustrated that this absorption route did not substantially affected adult and children health.
Effect of arc current on SiC fabrication from rice husk ash and diatomite in electric arc discharge furnace
Authors: Van Trung Trinh
Published: March 2024

Silicon carbide (SiC) was synthesized from Vietnamese rice husk ash and diatomite via the Acheson process in a graphite electric arc furnace. In this type of furnace, arc current generates temperature and therefore effect on the formation of SiC. The influence of arc current at 100, 150 and 200 A was investigated. Scanning electron microscopy and energy dispersive spectroscopy, XRD and Raman spectroscopy were performed to analyze the formation of SiC materials. Results showed the weight percentage of SiC in the synthesized product increased as the arc current increased.
Substituent effects on the antioxidant capacity of monosubstituted diphenylamines: a DFT study
Authors: Thao Pham Thi Thu , Thong Nguyen Minh , Vo Quan V. , Van Bay Mai , Quang Duong Tuan , Nam Pham Cam
Published: March 2024

There are undesirable effects leading to considerable changes in the properties of polymers and plastics since exposing to oxygen undergo oxidative degradation. Therefore, investigation of the bond dissociation enthalpies (BDEs) of N‐H bond for a series of monosubstituted diphenylamines is great interest. In this study, DFT‐based method B3P86/6‐311G was employed to perform this task. In comparison with the available experimental data, this method could reproduce the BDE(N‐H)s values more accuracy. Effects of substituents and substitution positions on the BDE(N‐H)s were also examined. Moreover, there is a good correlation of BDE(N‐H)s with the Hammett's substituent constants. Depending on the nature of substituents, electron withdrawing groups increase the BDE(N‐H)s but electron donating ones reduce the BDE(N‐H)s. The hydrogen atom transfer processes from N‐H bond of these diphenylamines to the peroxyl radical (CH3OO•) were also analyzed via potential energy surfaces and kinetic calculations.
A new xanthone from the lichen Parmotrema praesorediosum (Parmeliaceae)
Authors: Chi Huynh Bui Linh , Phung Nguyen Kim Phi
Published: March 2024

Two xanthone compounds, praesorexanthone A (1) and praesorexanthone B (2), were isolated from the lichen Parmotrema praesorediosum (Nyl.) Hale (Parmeliaceae). Among them, praesorexanthone B is a new natural compound. Their chemical structures were unambiguously determined by the analysis of 1D and 2D NMR and high resolution ESI mass spectroscopic data, as well as by comparison of their NMR data with the ones in the literature.
Development of Green protocols for the synthesis of 1H‐benzo[d]imidazolo aryl amide derivatives and evaluation of their biological activity
Authors: Laxminarayana E. , Srinivasa Reddy B. , Venkata Ramana Reddy Ch.
Published: March 2024

Benzimidazole scaffold containing chemical derivatives show superior biological activity. In view of this, we synthesized a combination of benzimidazole and aryl amides. The target compounds (6a‐j) were synthesized using ethyl 3‐iodobenzoate and benzimidazole as starting materials under microwave conditions. The synthesized compounds were screened against gram (+ve) and gram (‐ve) bacteria as well as for their anti‐oxidant activity. Compound 6a was proved to be most active in inhibiting the DPPH free radical.
A green process PEG‐600 mediated on‐pot, alternative synthesis of 3‐methyl‐2‐(((1‐methyl‐1H‐benzimidazole‐2‐YL) sulfonyl) methyl) quinazolin‐4(3H)‐one
Authors: Bireddy Srinivasa Reddy , Konkala Veera Swamy , Dubey Pramod Kumar
Published: March 2024

Condensation of 2‐((1H‐benzo[d]imidazol‐2‐yl)thio)acetic acid (1) with anthranilamide (2) in PEG‐600 (polyethylene glycol), at 100 oC for 3hr. gave 2‐(((1H‐benzo[d]imidazol‐2‐yl)thio)methyl)quinazolin‐4(3H)‐one (3). Treatment of 3 with DMS, DES and Ph‐CH2‐Cl, individually in PEG‐600, at RT for 1 hr. without using any base, followed by easy process resulted in 4 (a‐c). The later on reaction with H2O2 in PEG‐600, for 3 hr, without using any base, followed by simple processing resulted in 5 (a‐c). Alternatively, 5 (a‐c) the sequence of reactions could be prepared by tandem procedure with good yields. Thus novel quinazolinone products have been prepared with new synthetic routes and strategies by using PEG‐600 as solvent, in polyethylene glycol (PEG‐600) in four routes. i.e. (tandem‐1, tandem‐2, stepwise‐1 and stepwise‐2) Probably, this is the first case of four variable but identical end‐products‐ giving tandem syntheses, under green conditions, of 5 (a‐c). Obviously, as figures pointed out, tandem‐1 route gave good yields compared to the stepwise routes. In this process PEG‐600 recycled and reused.
Highly effective photocatalyst of TiO2 nanoparticles dispersed on carbon nanotubes for methylene blue degradation in aqueous solution
Authors: Quyen Nguyen Duc Vu , Khieu Dinh Quang , Tuyen Tran Ngoc , Tin Dang Xuan , Diem Bui Thi Hoang , Dung Ho Thi Thuy
Published: March 2024

In the present study, titania nanoparticles are highly dispersed on carbon nanotubes via hydrolysis process of tetra‐isopropyl‐orthotitanate Ti[OCH(CH3)2]4 (TPOT). The obtained composite (TiO2/CNTs) is characterized by modern methods. The anatase‐TiO2 phase is realized based on X‐ray diffraction spectrum at different pHs of hydrolysis solution. The band gap of TiO2/CNTs (Eg) is calculated by Tauc method using diffuse reflectance spectroscopy (DRS). The TiO2/CNTs composite plays as an active photocatalyst for methylene blue (MB) decomposition in aqueous solution. The effect of time to photocatalytic ability of TiO2/CNTs composite is described using Langmuir‐Hinshelwood kinetic model. The values of enthalpy variation (ΔH), entropy change (ΔS) and Gibbs free energy variation (ΔG) of the decomposition of MB are determined from thermodynamic study. In the range temperature from 283 K to 323 K, the positive values of ΔH and negative value of ΔG confirms endothermic and spontaneous nature of MB degradation. With the increase of temperature, the reaction occurs more easily, which is proved by more negative values of Gibbs free energy calculated from Van't Hoff equation.
Characterization of liquid deproteinized natural rubber prepared via oxidative degradation
Authors: Thuong Nghiem Thi , Manh Nguyen Duc , Tue Nguyen Ngoc
Published: March 2024

In the present work, liquid deproteinized natural rubber (LDPNR) was prepared by oxidative depolymerization of deproteinized natural rubber using hydrogen peroxide (H2O2) and sodium nitrite (NaNO2) as oxidizing reagents. Structural characterization of LDPNRs was performed using FT‐IR, 1H‐NMR, 13C‐NMR, and Heteronuclear Multiple Quantum Coherence (HMQC) spectroscopy. After degradation, the intensity of vibration mode at 1660 cm‐1 (νC=C) decreased, indicating the decrease in the number of C=C bonds in the NR chain. 1H‐NMR signals at 1.6 ppm and 13C‐NMR signals at 40.0 ppm appeared in the NMR spectra of LDPNR prepared in acidic condition suggesting the occurrence of isomerization from cis‐1,4‐isoprene units to trans‐1,4‐isoprene units. Epoxidation also occurred during degradation of DPNR as a side reaction. End groups of LDPNRs were found to depend on pH of reacted latex. LDPNR prepared in pH 5‐6 contains aldehyde end group, while LDPNR prepared at pH 8‐9 has a hydroxyl end group. The gel content of LDPNRs was found to reduce compared to that of DPNR, significantly. GPC was employed to determine molecular weight of LDPNRs. The results show that the degradation in acidic medium behaves more effectively in comparison to in alkaline medium.
Morphology and properties of polybutylene succinic and cassava starch blend: Effect of esterification catalysts on graft copolymer formation
Authors: Duc Vu Minh , Giang Nguyen Chau
Published: March 2024

The purpose of this research is to produce of esterified thermoplastic starch (ETPS) for reactive extrusion melt‐blending with polybutylene succinate (PBS) in film blowing application. Esterification TPS named M‐TPS and T‐TPS were prepared from cassava starch, glycerol (plasticizer), and maleic anhydride (MA), tartaric acid (TA) as reactive compatibilizers in a twin extruder, respectively. FTIR results showed that esterification reactions were successfully formed between both MA and TA with cassava starch. The esterified TPSs was then melt blended with PBS in the presence of four kinds of esterification catalysts. The effect of compatibilizer contents on the blend properties was studied in terms of tensile properties, melt flow index (MFI), and electron scanning microscopy (SEM). The results show that TA induced better compatibilization effect than MA did, as evidenced by the PBS/T‐TPS blend possessing higher strength than these of PBS/M‐TPS, although SEM images showed structural morphology of both blends is similar. The effect of the esterification catalyst type and contents on properties of the PBS/T‐TPS blend was also studied. The results from the Molau test confirmed the formation of graft‐copolymer (PBSgT‐TPS) at the interface of two phases of the blend when compatibilizers were added in the presence of an organotin compound catalyst.
Solar light‐driven photocatalyst‐enzyme attached artificial photosynthetic system for regeneration and production of 1,4‐NADH and L‐glutamate
Authors: Singh Chandani , Kumar Abhishek , Yadav Rajesh K. , Gole Vitthal L. , Dwivedi D. K.
Published: March 2024

In artificial photosynthesis process the photocatalyst‐enzyme attached system is a best strategy to utilize solar energy for solar chemical/fuels production. Herein, we prepared a solar light active graphene‐based photocatalyst received by the covalent attachment of 9‐aminoanthracene (AA) chromophore with chemically converted graphene (CCG) for highly efficient 1,4‐NADH regeneration (79.9 %) and conversion of α‐ketoglutarate (α‐KG) in to L‐glutamate (L‐GM) (88.3 %) in 2 hrs. The present result is a benchmark example of highly selective solar light active enzyme based artificial photosynthetic system for selective formation of L‐GM from α‐KG.
Preparation of CaCO3 nano and microparticles from phosphogypsum of Dinh Vu DAP plant, Viet Nam
Authors: Phuong Dang Ngoc , Chi Ngo Kim , Le Minh Tran , Luat Hoang Huu , Truyen Chu Quang , Lam Tran Dai
Published: March 2024

This study reports creating CaCO3 nanoparticle (NPs) and microparticles (MPs) from treated phosphogypsum of Dinh Vu Diamon phosphate plant in Vietnam. In this research, CaCO3 NPs and MPs were received in the system of Ca(OH)2 ‐ CO2 gas ‐ H2O by aeration method. The research samples are characterized by ultraviolet visible spectrophotometry (UV‐vis), scanning electron microscopy (SEM), X‐ray diffraction (XRD) and dynamic light scattering (DLS). The study investigated the conditions for obtaining calcium carbonate NPs and MPs when changing the aeration speed of CO2 from 40 to 120 ml/min, the concentration of Ca(OH)2 from 0.04 M to 0.5 M, the temperature from 28 to 60 oC. This research showed that the clear influence of Ca(OH)2 concentration and reaction temperature on the CaCO3 particle size in the CO2‐Ca(OH)2 system. CaCO3 morphological structure has the form of calcite with rhombohedral block (rhomboid cylindrical box).
Simultaneous determination of acepromazine and atropine residues in porks, livers, kidneys by Ultra‐High‐Performance Liquid Chromatography‐Tandem Mass Spectrometry
Authors: Hieu Tran Quang , Phuong Pham Kim , Tan Nguyen Thanh , Thang Nguyen Quoc
Published: March 2024

A method for determining the tranquilizers Acepromazine (ACP) and Atropine(ATP) in pig tissues (kidneys, livers, and porks) by using UPLC‐MS/MS has been developed. The liquid chromatographic separation and mass spectroscopy of the two substances have also been optimized. The justification data of the methods were: limit of detection (LOD) and limit of quantification (LOQ) 0.15 and 0.50 ng/mL for ATP, 0.16 and 0.5 ng/mL for ACP in all matrix samples. Calibration curves exhibited linearity in concentration varieties from LOQ to 12 ng/mL for ACP and LOQ to 20 ng/mL for ATP. Recovery, intra‐day precision, and inter‐day precision were determined at spiked analytes concentration of 2.0, 5.0, and 10 ng/mL for ACP and at analyte concentrations of 2.0, 6.0, 15.0 ng/mL for ATP. Recovery ranged from 98.26 to 119.43 % for ACP and 97.45 to 118.44 % for ATP. The effect of the matrix sample of the technique was found to be insignificant. The confirmed method has been applied to ascertain the content of two substances in the porks, kidneys, and livers of 16 pigs, injected Prozil Fort ‐ Veterinary Medicine (contained ACP and ATP) at different intervals. This work supplied a new method for scientists, which could be applied to determine the tranquilizers Acepromazine (ACP) and Atropine(ATP) in pig tissues.
Oxidation‐reduction reactions in geochemistry
Authors: Biswas Salah Uddin , Karmakar Kripasindhu , Saha Bidyut
Published: March 2024

There are more than hundred elements in the periodic table and many of them are associated with various geochemical processes. Most of the elements can show more than one oxidation states, therefore, reactions involving oxidation and reduction are of very much importance in geochemistry. Since every change (chemical or physical) is associated with the change of energy, hence for every single process, there should be a reliable way for quantitative measurement of energy change. In case of any redox process, the energy change can be quantitatively expressed in terms of reduction potential of that process. For better understanding of a geochemical process, previously known reduction potentials can be used. The main importance of reduction potentials in geochemistry is for understanding the frequent concentration and enrichment of various elements in deposits formed under extremely reducing or oxidizing conditions.
TD‐DFT benchmark for UV‐Vis spectra of coumarin derivatives
Authors: Van Bay Mai , Hien Nguyen Khoa , Tran Phan Thi Diem , Tuyen Nguyen Tran Kim , Oanh Doan Thi Yen , Nam Pham Cam , Quang Duong Tuan
Published: March 2024

The predictive performances for maximum absorption wavelength of the PBE, BP86, PBE0, B3LYP, M06, M06‐2X, CAM‐B3LYP, LC‐wPBE, APDF, wB97XD, and PW6B9D3 functionals have been benchmarked through comparison of maximum absorption wavelength values between calculation and experiment of 21 coumarin derivatives. For the results obtained from direct calculation by these functionals, the predictive performance decreases gradually in the following order: B3LYP > APDF > M06 > PW6B9D3 > PBE0 > BP86 > PBE > M06‐2X > CAM‐B3LYP > wB97XD > LC‐wPBE. B3LYP functional gives the best predictive performance, with the smallest value of the mean absolute error (MAE = 15 nm) and the root mean square deviation (RMSD=19 nm). When using the results obtained through correction based on the linear correlation, the predictive performance decreases gradually in the following order: M06‐2X > PBE0, M06, PW6B9D3 > B3LYP, APDF > CAM‐B3LYP, LC‐wPBE, wB97XD > PBE and BP86. M06‐2X functional gives the best predictive performance, with the smallest values of MAEfix (7 nm) and RMSDfix (9nm). The correction is very necessary because the values of the corrected maximum absorption wavelengths are closer to the experimental maximum absorption wavelengths. The values of MAEfix and RMSDfix are much smaller than those of MAE and RMSD.
Lipid, fatty acid composition and molecular species of betaine lipid in the green algae Halimeda incrassata Lamx. collected from Truong Sa archipelago
Authors: Hue Pham Thu , Anh Nguyen Van Tuyen , Trung Do Thi Thanh , Long Pham Quoc , Tien Dam Duc , Van Tran Thi Thanh , Thanh Le Tat
Published: March 2024

In this study, lipid classes, fatty acid composition, and molecular species of betaine lipid of the green algae Halimeda incrassata Lamx., collected from Truong Sa archipelago, have been identified. Five lipid classes including Pol, ST, FFA, TG, HW have detected on TLC chromatography. In the total lipid, 21 fatty acids have been indicated, in which, 4 fatty acids belonging to the PUFAs group with the valuable bioactivities and the high content are ALA, GLA, AA, EPA. From Halimeda incrassata, this is the first time 17 betaine lipid molecular species have been identified by HPLC‐HRMS technique. Interestingly, all of these molecular species belong to the diacylglyceryl‐N,N,N‐trimethylhomoserine group, which is the characteristic composition of the non‐flower plant.
Study on fabrication of MnO2/CNTs composite by electrolysis in neutral solution and its applicability as cathode materials in Mg‐ion batteries
Authors: Van Vy Uong , Que Le Xuan
Published: March 2024

Effects of electrolysis conditions such as Mn2+ ions, and CNTs concentration, temperature, and solution stirring on electrochemical precipitation of MnO2/CNTs composite on SS 304 stainless steel anode electrodes were studied by cyclic voltammetry (CV) method. Results show that the MnO2/CNTs was fabricated at the electrode potential was more positive than 0.8 V/SCE with a suitable solution composition of 0.5 M Na2SO4, 0.4 M MnSO4 and CNTs 0.2 g/L, at 80 oC, and stirring speed ranging from 100 to 200 rpm. The obtained MnO2/CNTs composite materials contained a crystalline phase of MnO2 akhtenskite. The presence of CNTs in the composite was observed by FESEM image. Electrochemical properties of the MnO2/CNTs composites were studied by CV method and galvanostatic charge‐discharge. The composite materials have good discharge capacity, its specific capacity was 92 mAh/g, after 35 charge‐discharge cycles the specific capacity of the material decreased to 69.2 mAh/g, equal to 75 % of the first cycle.
Synthesis and alpha ‐ inhibitory activity of lupane type С2‐benzylidene‐ triterpenoids
Authors: Khusnutdinova Elmira F. , Ha Nguyen Thi Thu , Giniyatullina Gulnara V. , Anh Le Thi Tu , Poptsov Alexander I. , Kazakova Oxana B.
Published: March 2024

A series of novel and previously synthesized lupane type С2‐benzylidene derivatives was evaluated on α‐glucosidase enzyme inhibition. Most of the tested compounds exhibited significantly better activity (1.8‐700 times higher) than the standard drug acarbose. The structure‐activity relationship indicated that the type of benzylidene moiety and C28‐substituent of lupane core plays an important influence on the activity. Methyl 2‐furfurylidene betulonate, m‐iodo‐benzylidene betulonic acid and 3‐pyridinylideno‐betulonic acid hydrazide have been founded as effective α‐glucosidase inhibitors and deserve further attention.
Molecular species of glycolipid and anti‐inflammation activity of lipid fractions in the green algae Halimeda incrassata Lamx. collected from Truong Sa, Viet Nam
Authors: Thanh Le Tat , Anh Nguyen Van Tuyen , Hue Pham Thu
Published: March 2024

In this study, 40 glycolipid molecular forms have been identified belonging to 3 groups of MGDG (12), DGDG (11), SQDG (17). The MGDG molecular forms count for a high concentration in the PUFA fatty acid component such as C18:2, 18:3, 20:4. The DGDG forms mainly contain saturated fatty acids and 1 double‐bonded while the SQDG forms have the intertwine between saturated fatty acids and super long and long‐chain HUFA fatty acids (over 20C and 4 double bonds) such as C20:4, 20:5 and 22:6. Results of biological activity test for three lipid fractions of Halimeda incrassata Lamx. seaweed have showed that they have anti‐inflammatory activities from 32.57±5.75 to 41.66±1.95 μg/mL, of which the highest is the polar lipid fraction. This showed that this is a potential source to continue screening for bioactive compositions to apply on the medicine and pharmacy.
A computational approach to explore the binding mechanism of secondary metabolites of Hamigera ingelheimensis with AgrA quorum sensing proteins
Authors: Basak Hriday Kumar , Paswan Uttam , Chatterjee Abhik
Published: March 2024

Bacterial resistance to existing antibacterials can be handled by focusing on the bacterial communication system, specifically bacterial quorum sensing system. Inhibiting AgrA‐DNA binding is an effective strategy for reducing the expression of diverse genes involved with the secretion of virulence factors by the Agr quorum sensing system. Hamigera ingelheimensis, a common soil fungus, produces several bioactive secondary metabolites including avellanin C which is a well‐recognised and deeply studied quorum sensing inhibitor. Among the several metabolites, we selected ten metabolites and other metabolites have been rejected either some of them were exhaustively studied or during primary docking screening, they did not show promising docking scores. These ten metabolites were docked with template protein (PDB ID: 4G4K) and with five homologies modelled AgrA proteins using AutoDock tool. Avellanin A, avellanin B and PF1171B showed a promising binding score with all the proteins with binding free energy less than ‐8.00 kcal.mol‐1. Molecular dynamics simulations suggest that their docked complexes are stable. These three metabolites have drug‐likeness features and thus have the tremendous prospect to be used as the AgrA inhibitors.
Hepatoprotective effect of water extract formulation from Stixis suaveolens and Pandanus tonkinensis against liver injury induced by acetaminophen and in vitroCCl4‐induced toxicity
Authors: Tung Bui Thanh , Hai Nguyen Thanh , Anh Duong Hong , Viet Pham Hung , Schmitz Oliver J. , Van Tuyen Nguyen , Anh Ngo Quoc
Published: March 2024

A herbal remedy formulation including Stixis suaveolens and Pandanus tonkinensis has been established to treat liver diseases in the North‐West region of Vietnam. This study aimed to provide in vitro as well as in vivo scientific evidences which illustrate the hepatoprotective effect of water extract of the above formulation. As a result, the highest oral dosage of water extract equivalent to 29.6 g/kg did not induce any toxic phenomena. Histopathological study showed that water extract formulation could reverse the damage caused by acetaminophen in mice. The water extract reduced significantly the level of ALT and AST enzyme, MDA, TNF‐α and IFN‐γ concentrations in mice treated with acetaminophen compared with control disease group. Furthermore, one of ten fractions from the formulation (F8) showed the strongest hepatoprotectivity in model of CCl4‐induced toxicity in HepG2 cells. Thus, the water extract formulation could be a potential candidate for the protection of liver from diseases.
Study on structural and electronic properties of rutile TiO2 using DFT + U approach
Authors: Thoa Tran Thi , Van Hung Hoang , Hue Nguyen Thi Minh
Published: March 2024

Effects of Hubbard parameters Ud, Up and Ud‐Up pairs on structural and electronic properties of rutile TiO2 have been investigated using the DFT + U method, wherein Ud, Up were applied to Ti 3d‐orbitals and O 2p‐orbitals, respectively. The Ud, Up parameters range from 3 to 10 eV. Calculations have shown that Up = 10 eV is the optimal value to describe both structural and electronic properties of rutile. For Ud, an increasing in value of Ud results in expansion of band gap. However, high values of Ud lead to discrepancy in lattice constants. The effect of Ud is in good agreement with previous works. The obtained results also indicated advantages of combination of Ud and the optimal Up. The combination not only decreases discrepancy in lattice constants but also enlarges band gap more than Ud correction. Thanks to the optimal Up, we have achieved a band gap of 2.92 eV only with Ud = 7 eV. The Ud‐Up pairs of 8‐10, 9‐10 and 10‐10 give band gaps which is suitable with the experimental value.
Utilization of natural surfactants: An approach towards sustainable universe
Authors: Mondal Subhodip , Acharjee Animesh , Saha Bidyut
Published: March 2024

A broad range of microorganisms produce biosurfactants, which are surface‐active compounds. They are molecules with both hydrophilic and hydrophobic domains that can lower the growth medium's surface tension and interfacial tension. Since they are nontoxic and biodegradable, biosurfactants can be used as a green substitute in various situations. Biosurfactants are also primarily used in the pharmaceutical and oil sectors, as well as in pollutant bioremediation. Aside from these, biosurfactants can be used in a wide range of food and agriculture industries, cosmetics, and skincare products. We sincerely hope that this review will help to understand the different applications of biosurfactants and their future potential.
In silico screening of natural antivirals as potential inhibitors of SARS‐CoV‐2 virus
Authors: Hang Ta Thi Thu , Khanh Do Thi Hong , Tung Bui Thanh
Published: March 2024

Coronavirus infectious disease 2019 (COVID‐19) is an infectious disease of the human respiratory tract caused by the SARS‐CoV‐2 virus. Spike protein is a class I glycoprotein trimeric TM involved in viral entry and infection. Four major targets to inhibit the SARS‐CoV‐2 virus are spike protein, angiotensin‐converting enzyme 2 (ACE2), main protease and the enzyme RNA‐dependent RNA polymerase (RdRp). In this study, we evaluated the inhibitory potential of natural antiviral compounds against spike protein, ACE2, main protease, RdRp targets by molecular docking and molecular dynamics simulations. Lipinski Rule of Five was used to evaluate the drug‐like properties of these compounds. The pkCSM tool was used to assess the pharmacokinetic parameters of prospective substances. Based on the ChemFaces database, we have collected 273 natural antiviral compounds. The results showed that the 7/273 compounds with the most potential to inhibit SARS‐CoV‐2 were: hinokiflavone, sotetsuflavone, mulberroside C, daphnoretin, morellic acid, digitoxin, and hypericin. Among them, sotetsuflavone is the most potent compound that inhibits four targets, with drug‐like properties, good intestinal absorption, and low toxicity. The molecular dynamics simulation results of the complexes are also relatively stable. As a results, in vitro and in vivo test should be carried out to verify the potential for COVID‐19 treatment of this compound.
Xestospongiene VN1, a new brominated polyunsaturated lipid from marine sponge Xestospongia testudinaria (Lamark, 1815)
Authors: Tai Bui Huu , Hang Dan Thi Thuy , Thung Do Cong , Trang Do Thi , Yen Pham Hai , Yen Duong Thi Hai , Huong Phan Thi Thanh , Dung Duong Thi , Cuong Ngo Cao , Thao Do Thi , Nhiem Nguyen Xuan , Van Kiem Phan
Published: March 2024

Phytochemical study on the methanol extract of the marine sponge Xestospongia testudinaria (Lamark, 1815) led to the isolation of one new ((6Z,8E,13E,15Z)‐6,14,16‐tribromo‐5,10‐dihydroxyhexadeca‐6,8,13,15‐tetraenoic acid named xestospongiene VN1, 1) and nine known brominated polyunsaturated compounds, xestospongiene z5 & z6 (2), xestospongiene z9 & z10 (3), xestospongiene S (4), xestospongic acid (5), xestospongic acid methyl ester (6), (13E,17E)‐18‐bromo‐octadeca‐13,17‐diene‐5,7,15‐triymoic acid (7), xestospongiene I & J (8), xestospongiene K & L (9), and xestospongiene C & D (10). The chemical structures of these compounds were elucidated by extensive spectroscopic analyses including HR‐ESI‐MS, 1D and 2D NMR, circular dichroism, and by comparison of the spectral data with those of previously reported data. This is the first report of these compounds from Vietnamese marine sponge X. testudinaria.
Constituents of Vernonia gratiosa Hance and their α‐glucosidase and xanthine oxidase inhibitory activities
Authors: Van Cong Pham , Van Hieu Ngo , Minh Bui Quang , Duc Ngo Viet , Trang Vu Thi , Hien Nguyen Thi Thu , Khanh Nguyen Viet , Anh Tran Thi Phuong , Dat Ton That Huu , Anh Le Tuan , Anh Hoang Le Tuan
Published: March 2024

Eight compounds, including 11β,13‐dihydrovernolide (1), apigenin (2), kaempferol (3), quercetin 3‐O‐methyl ether (4), quercetin (5), syringaresinol‐β‐ᴅ‐glucoside (6), 3‐hydroxy‐1‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐[4‐(3‐hydroxy‐1‐(E)‐propenyl)‐2,6‐dimethoxyphenoxy]propyl‐β‐ᴅ‐glucopyranoside (7), and 5‐(methoxymethyl)‐1H‐pyrrole‐2‐carbaldehyde (8) were isolated from the aerial part of Vernonia gratiosa. Their chemical structures were identified by NMR experiments along with the comparison of their spectroscopic data with those reported in the literature. In addition, all compounds were evaluated for their inhibitory effects on α‐glucosidase and xanthine oxidase. Among them, only compound 7 showed the significant inhibition of α‐glucosidase with an IC50 value of 47.08 ± 3.98 μg/mL and xanthine oxidase activity with an IC50 value of 26.92 ± 1.04 μg/mL. Compounds 1‐5 were firstly isolated from V. gratiosa, while compounds 6‐8 were reported from the genus for the first time. This is the first study about this species growing in Vietnam.
Synthesis and characteristics of some new polythiophene containing α,β‐unsaturated carbonyl groups
Authors: Duong Tran Thi Thuy , Dua Nguyen Thi , Linh Nguyen Ngoc , Nguyet Le Thi , Tuyet Le Thi Minh , Hien Nguyen , Linh Duong Khanh , Hung Ha Manh , Oanh Doan Thi Yen , Chinh Nguyen Thuy , Oanh Vu Thi Ngoc , Ha Hoang Thu , Trung Vu Quoc
Published: March 2024

Some new polythiophenes with α,β‐unsaturated carbonyl groups were synthesized using a chemical oxidative coupling reaction. IR, 1H‐NMR, UV‐Vis and Raman spectra were used to confirm the expected structure of polymer which is suitable for the suggested synthetic route. Two of all synthesized polythiophenes were soluble well in DMSO and CHCl3 solvent. The morphology, thermal stability, photoluminescence properties and conductivity of polymers were studied. The trans‐configuration of α,β‐unsaturated carbonyl side chain improve featured properties of these polymers.
Electrophoresis deposition of Au‐nanoparticles on FTO electrode for As(III) detection
Authors: Thang Nguyen Canh Minh , Linh Lam Gia , Anh Nguyen Hoang , Nguyen Huynh Le Thanh , Hai Le Viet , Hoang Nguyen Thai
Published: March 2024

Gold nanoparticles (AuNPs) were synthesized via redox reaction, using EDTA as a protecting and reducing agent, with HAuCl4 as precursor and seed solution. The appropriate reaction condition was found out, with the ratio of EDTA:HAuCl4 = 10:1, 40 μL of seed solution and stirring time of 5 minutes. The UV‐Vis spectroscopy observed that the appearance of two absorption peaks were at 574 and 755.5 nm with the average size of AuNPs was 64.5 nm, the zeta potential was positive. The synthesized AuNPs were deposited on FTO electrode by electrophoresis deposition. The results of solid UV‐Vis and SEM images showed that the spherical AuNPs ranging from 40 to 60 nm were deposited onto FTO to fabricate the AuNPs/FTO electrodes. The electrochemical activity of AuNPs/FTO were investigated based on the redox reaction of hydroquinone; the CV results showed the electrode with applied potential at 20 V for 60 minutes has the superior performance. The analysis of As(III) were conducted by AS‐SWV technique. The results showed that AuNPs/FTO electrode enable to detect As(III) at the concentrations higher than 5 ppb that is suitable for the WHO standard of domestic water.
Phytochemistry of the Aerial parts of Magnolia coriacea collected in Ha Giang, Viet Nam
Authors: Ninh Pham Thi , Dung Nguyen Thi , Van Loc Tran , Ha Chu Thi Thu , Thao Tran Thi Phuong , Van Chien Tran
Published: March 2024

Nine compounds, including two sesquiterpenes [((+)‐spathulenol (1), caryophyllenol‐II (2)], five flavonol glycosides [rutin (3), quercitrin (4), rhamnocitrin 3‐rutinoside (5), oxytroflavoside G (6), curcucomoside D (7)], and two hydrocarbons [2‐phyten‐1‐yl‐caprylate (8) and tritriacontan‐1‐ol (9)] were reported for the first time from the leaves and twigs of Magnolia coriacea. Their detailed structures were confirmed by 1D and 2D NMR spectra analyses and compared to the published data.
The potential of 2,5‐dichloroaniline and ammonium thiosulphate and their combination as nitrification inhibitors
Authors: Mehmood Faisal , Khadim Zeeshan , Zaman Qamar Uz
Published: March 2024

In the current research, nitrification inhibitors such as 2,5‐dichloroaniline, ammonium thiosulphate, and their combination (1:1) were used to slow down the nitrification process to increase the nitrogen availability for crops. The various levels of 0.1, 0.25, and 0.5 % were used for each inhibitor on three types of soil. Leachates were collected from each treatment, add 1ml of 0.1 % chromotropic acid solution and 6 mL of concentrated sulfuric acid, swirled in the flask, and left at room temperature, yellow color was developed after 45 minutes. Then absorbance reading was noted for each sample by spectrophotometer at the wavelength of 430 nm. NO3‐ ‐N content was determined by the standard curve method. From inhibitors, the combination of both inhibitors shows minimum NO3‐ ‐N content as 154.29 and 112.83 ppm than other chemicals for 2nd and 14th days respectively. From soil, Sheikhupura soil shows minimum NO3‐ ‐N in the leachate as 176.26 (2nd day) and 105.03 ppm (14th day) as compared to other soils. From the levels, 0.25 % shows minimum NO3‐ ‐N as 118.05 (2nd day) and 63.18 ppm (14th day) as compared to other levels. The combination (1:1) and the level 0.25 % were found more suitable to reduce the nitrification process in Sheikhupura soil.