bluuebunny/crossref_metadata_2025 huggingface dataset:
Heuristic reoptimization of time‐extended multi‐robot task allocation problems
Authors: Bischoff Esther , Kohn Saskia , Hahn Daniela , Braun Christian , Rothfuß Simon , Hohmann Sören
Published: March 2024

Providing high quality solutions is crucial when solving NP‐hard time‐extended multi‐robot task allocation (MRTA) problems. Reoptimization, that is, the concept of making use of a known solution to an optimization problem instance when the solution to a similar problem instance is sought, is a promising and rather new research field in this application domain. However, so far no approximative time‐extended MRTA solution approaches exist for which guarantees on the resulting solution's quality can be given. We investigate the reoptimization problems of inserting as well as deleting a task to/from a time‐extended MRTA problem instance. For both problems, we can give performance guarantees in the form of an upper bound of 2 on the resulting approximation ratio for all heuristics fulfilling a mild assumption. We furthermore introduce specific solution heuristics and prove that smaller and tight upper bounds on the approximation ratio can be given for these heuristics if only temporal unconstrained tasks and homogeneous groups of robots are considered. A conclusory evaluation of the reoptimization heuristic demonstrates a near‐to‐optimal performance in application.
Highly thermally conductive and EMI shielding composite fabricated via free‐radical polymerization of poly acrylic acid assisted by expanded graphite with liquid metal‐grafted MXene
Authors: Cho Jangwoo , Kim Jooheon
Published: March 2024

Polymer composites offer numerous benefits, including low cost, easy processability, and diverse applications. In this work, we fabricated a composite material with high thermal conductivity and electromagnetic interference (EMI) shielding performance using EGaIn, a liquid metal (referred to as LM in this paper), MXene (MX), and expanded graphite (EG) as multifunctional fillers, along with polyacrylic acid (PAA). LM was used to exfoliate MX under the effect of shear force, which not only reduced the size of MX but also increased the aspect ratio of the 2D‐structured MX. MX was filled into the pores of EG to make a heat transfer path, thereby enhancing its thermal conductivity, mechanical properties, and EMI SE properties. LM served as the initiator of free‐radical polymerization to convert acrylic acid (AA) into PAA. Finally, the LMMX/EG/PAA composite was hot‐pressed to make the heat‐transfer path dense. As a result, the LMMX/EG/PAA composite exhibited a thermal conductivity of 1.88 W/m·K and an EMI shielding effect of 52 dB.
N‐DMBI Doping of Carbon Nanotube Yarns for Achieving High n‐Type Thermoelectric Power Factor and Figure of Merit
Authors: Suzuki Hiroo , Kametaka Jun , Nakahori Shinya , Tanaka Yuichiro , Iwahara Mizuki , Lin Haolu , Manzhos Sergei , Kyaw Aung Ko Ko , Nishikawa Takeshi , Hayashi Yasuhiko
Published: March 2024

The application of carbon nanotube (CNT) yarns as thermoelectric materials for harvesting energy from low‐grade waste heat including that generated by the human body, is attracting considerable attention. However, the lack of efficient n‐type CNT yarns hinders their practical implementation in thermoelectric devices. This study reports efficient n‐doping of CNT yarns, employing 4‐(1, 3‐dimethyl‐2, 3‐dihydro‐1H‐benzimidazole‐2‐yl) phenyl) dimethylamine (N‐DMBI) in alternative to conventional n‐dopants, with o‐dichlorobenzene emerging as the optimal solvent. The small molecular size of N‐DMBI enables highly efficient doping within a remarkably short duration (10 s) while ensuring prolonged stability in air and at high temperature (150 °C). Furthermore, Joule annealing of the yarns significantly improves the n‐doping efficiency. Consequently, thermoelectric power factors (PFs) of 2800, 2390, and 1534 µW m−1 K−2 are achieved at 200, 150, and 30 °C, respectively. The intercalation of N‐DMBI molecules significantly suppresses the thermal conductivity, resulting in the high figure of merit (ZT) of 1.69×10−2 at 100 °C. Additionally, a π‐type thermoelectric module is successfully demonstrated incorporating both p‐ and n‐doped CNT yarns. This study offers an efficient doping strategy for achieving CNT yarns with high thermoelectric performance, contributing to the realization of lightweight and mechanically flexible CNT‐based thermoelectric devices.
A modeling strategy for the shear and flexural performance prediction of SFRC beams without stirrups accounting for the variability of properties
Authors: Benedito André Vitor , Vanalli Leandro , Krahl Pablo Augusto , Martins Carlos Humberto , de Andrade Silva Flávio
Published: March 2024

The behavior of steel fiber reinforced concrete (SFRC) is highly dependent on mix design, where the properties of its components, such as cementitious matrix and fibers, impact the physical and mechanical properties of the composite. Incorporating steel fibers into concrete modifies its physical properties, potentially leading to fiber segregation and resulting in a nonuniform distribution of the fibers within the material. In experimental studies, an increase in fiber volume has been found to change the failure mode of SFRC beams from shear to flexure, and numerical investigations have shown that randomness in fiber distribution can significantly influence the behavior of the composite. Therefore, this study aims to develop a numerical model that considers variations in material properties to simulate the change in the failure mode of SFRC beams due to variations in fiber volume. The failure and yielding parameters were initially established and integrated into the concrete damaged plasticity (CDP). Subsequently, the response of both steel and concrete to tension or compression stresses was ascertained. Finally, the appropriate meshes and finite elements were chosen for the simulation. In the final approach, two methods were employed to introduce randomness into the beam. One divided the beam into different vertical segments: 30, 45, and 90, and the other combined vertical and horizontal segments: 30 vertical with 4 horizontal, 45 vertical with 5 horizontal, and 90 vertical with 10 horizontal. A script was developed in Python to automatically insert the properties. The numerical model successfully captured the change in failure mode from shear to flexure resulting from fiber volume increase. Vertical and horizontal segments increased toughness due to crack deviation, better predicting cracking pattern and loading capacity for the highest fiber contents.
Chemical study of the stem bark of Phyllanthus emblica (Phyllanthaceae)
Authors: Khoa Phan Thanh , Quy Pham Bao , Lien Do Thi My , Phung Nguyen Kim Phi , Tuyet Nguyen Thi Anh
Published: March 2024

From the ethyl acetate extract of the stem bark of Phyllanthus emblica, a mixture of triterpene glycosides (1) and six compounds (2‐7) were isolated. The structure of these compounds were established as 3‐O‐α‐L‐arabinopyranosyloleanolic acid (1a), 3‐O‐α‐L‐arabinopyranosylursolic acid (1b), 16‐dehydropregnenolone (2), periplogenin (3), betulin (4), phyllanthol (5), gallic acid (6) and methyl gallate (7) by 1D, 2D NMR spectroscopies, and high resolution ESI‐MS analysis, as well as comparison with those reported in the literature. The compounds (1a), (1b), (2) and (3) were found for the first time from this genus.
Spinel‐layered Li2MnTiO4+z cathode material for Li‐ion batteries prepared by a sol‐gel method
Authors: Hung Vu Ngoc , Van‐Duong Dao , Trang Tran Thi
Published: March 2024

Herein, the sol‐gel method is conducted to synthesize the spinel‐layered Li2MnTiO4+z (0.5LiMnTiO4•0.5Li2Mn0.5Ti0.5O3) nanoparticles as a cathode material for Li‐ion batteries. The structural and electrochemical properties of the material are investigated by means of X‐ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, and charge‐discharge tests. The obtained sample shows a high capacity of 200 mAh g‐1 with a capacity retention of 90 % after 60 cycles at C/5.
Synthesis of furfural from Acacia mangium wood sawdust‐derived xylose by continuous distillation method using sulfonated carbonaceous catalyst from the same source
Authors: Chung Nguyen Hoang , Hoai Nguyen Thi Thu , Dien Le Quang
Published: March 2024

In this study, the hydrolysate containing ~15 g/L of xylose, which was obtained from Acacia mangium wood sawdust was used for the synthesis of xylose by a continuous distillation method. The synthesis was conducted at 150 °C for 7 h using a carbon‐based sulfonated catalyst (CBSC) from the same biomass source with an acid density of about 4.0 mmol/g. The CBSC showed its efficient catalytic activity in the dehydration of xylose to furfural. Under the optimal catalyst dosage of 20 wt% over xylose, the yield of furfural was 20.4 mol% and 34 wt% of xylose was transformed to furfural. The results presented a successful utilization of a wood‐derived solid acid catalyst for production of furfural from the same biomass source as a sustainable production of furans for biofuel additives.
Pyrolysis of cashew nut shell: A parametric study
Authors: Nam Nguyen Hong , Anh Khuong Duy , Truc Le Gia Thanh , Ha Truong An , Ha Vu Thi Thu
Published: March 2024

Cashew nut shell, a waste from cashew nut production, could become a potential biomass feedstock for gasification. In this study, a complete parametric study of cashew nut shell was conducted in pyrolysis conditions that are relevant to industrial processes. The effects of temperature, heating rate and residence time on the shrinkage, char yield, char energy, as well as characteristics of cashew nut shell (ash content, volatile matter, fixed carbon content, and heating value) have been deeply investigated. The study results suggest ideas for the development of advanced pyrolysis techniques to better control the char product characteristics, hence serving for multiple purposes, such as energy or activated carbon production.
Chemical constituents from the leaves of Styrax annamensis Guill
Authors: Tra Nguyen Thanh , Anh Tran Dang , Van Cuong Pham , Ha Nguyen Thi Thu , Anh Le Thi Tu , Cham Ba Thi , Son Ninh The
Published: March 2024

A phytochemical study of the ethyl acetate extract (EtOAc) of Styrax annamensis leaves resulted in the isolation and determination of six known compounds, including three nor‐neolignans type 2‐phenylbenzofurans egonol (1), egonoic acid (2) and (–)‐machicendiol (3), two lignans styraxin (4) and vladinol D (5), and a triterpenoid pomolic acid (6). The chemical structures of these compounds were determined by NMR spectroscopies, and MS data. This is the first time to isolate these compounds from S. annamensis species. Compounds 3 and 5 have also been observed from genus Styrax for the first time.
Chemical constituents of Launaea sarmentosa roots
Authors: Hanh Le Hong , Dung Phung Duc , Huy Lieu Dieu , Duong Ngo Thi Thuy , Wacharasindhu Sumrit , Phung Nguyen Kim Phi , Chi Huynh Bui Linh
Published: March 2024

By investigating the chemical constituents of the roots of Launaea sarmentosa, collected at Can Gio beach, Can Gio district, Ho Chi Minh city, nine compounds were isolated including α‐amyrin acetate (1), β‐amyrin acetate (2), lupeol acetate (3), ψ‐taraksasterol acetate (4), luteolin (5), 4‐allyl‐2,6‐dimethoxyphenol glucopyranoside (6), scorzoside (7), ixerisoside D (8) and 9α‐hydroxypinoresinol (9). To the best of our knowledge, all compounds were reported in other species, but this is the first time they were known in L. sarmentosa. Four compounds (1‐4) from the n‐hexane extract were identified by 4‐dimethylaminopyridine‐catalyzed benzoylation. Their chemical structures were elucidated by means of 1D and 2D NMR, HR‐ESI‐MS data analysis and compared with those reported in the literature.
Diterpene glycosides and phenolic compounds from the fruits of Xanthium strumarium
Authors: Van Kiem Phan , Hoang Nguyen Huy , Thu Vu Kim , Tai Bui Huu , Nhiem Nguyen Xuan
Published: March 2024

Seven compounds including two diterpene glucosides atractyloside (1), carboxyatractyloside (2), and five phenolic compounds as 5‐O‐caffeoylquinic acid (3), 1,5‐di‐O‐caffeoylquinic acid (4), 2,3‐dihydroxy‐1‐(4(hydroxy‐3‐methoxyphenyl)‐propan‐1‐one (5), (erythro)‐1,2‐bis(4‐hydroxy‐3‐methoxyphenyl)‐1,3‐propandiol (6), and p‐hydroxybenzaldehyde (7) were isolated from the fruits of Xanthium strumarium. Their chemical structures were determined using ESI‐MS, 1D NMR, and 2D NMR spectra as well as by comparison of the spectral data with those reported in the literature. Compounds 4 and 5 were reported from Xanthium genus for the first time. To our best knowledge, all these compounds were firstly reported from X. strumarium growing in Vietnam.
A Review of some catalysts and promoters used in organic transformations
Authors: Acharjee Animesh , Saha Bidyut
Published: March 2024

Catalytic processes are indeed greener modification as they completes in much shorter time with minimizing the need of external energy source with atom economy and high selectivity. In this article we presented a short review on utlisation of different catalysts such as ionic liquids, transition metal ions, nano particles, surfactants, amino acids etc. for C‐C coupling reactions to oxidation reactions. Stereoselective and regioselective transformations are also carried out using catalyst in organic synthesis. Use of catalyst in rate enhancement of oxidation reaction is of immense interest and a surplus rate increment is obtained by use of promoters.
A study on the application of Fenton process followed by coagulation for treatment of landfill leachate
Authors: Dung Nguyen Trung , Van Thanh Bui , Huy Nguyen Nhat
Published: March 2024

In this study, leachate from Quang Hanh landfill (Quang Ninh) was treated by a combination of Fenton and coagulation processes. The experiment was conducted with various Fenton (i.e., pH, H2O2/Fe(II) ratio and dosage, and reaction time) and coagulation (i.e., dosage, aeration time, and flocculant concentration) conditions to determine the best condition for treatment of the leachate. Regarding Fenton process, under the best condition, the COD removal efficiency of around 80 % with an inlet concentration of 624±80 mg/L, meeting QCVN 25:2009/BTNMT (Column B2) while 75 % of color, 25 % of ammonia, and 12 % of TSS were removed, creating favorable conditions for the next stage of treatment by coagulation. In terms of coagulation, CaO and polyaluminum chloride (PAC) were sequentially used for treating the leachate after Fenton process. After treatment with CaO (6 g/L, 180 min), PAC (1,500 mg/L), and A101 (2 mg/L), the removal efficiencies achieved 85 %, 99 %, 99‐99.5 %, and 88 % for COD, color, ammonia, and TSS, respectively, and the effluent can meet the treatment requirement by the discharge standards.
Compatibility of epoxidized natural rubber and polyaniline blend
Authors: Ha Nguyen Thu , Hoa Nguyen Thi , Van Tung Vu , Anh Nguyen Lan , Thuy Tran Thi , Ougizawa Toshiaki
Published: March 2024

The compatibility of binary blend of epoxidized natural rubber and polyaniline was investigated. Epoxidized natural rubber with 25 mol% of epoxy group content was prepared through epoxidation of deproteinized natural rubber in latex stage. Blends of epoxidized natural rubber and polyaniline with various ratios were prepared. The compatibility of the blends was examined through differential scanning calorimetry measurement and scanning electron microscopy observation. Obtained result showed that the presence of epoxy group significantly improved the compatibility of binary blends of epoxidized natural rubber and polyaniline blends. The compatibility significantly enhanced the electrical conductivity of epoxidized natural rubber/polyaniline blends.
Effect of stabilizing and brightening agents and some operated conditions on electroplating kinetics of NiCu alloys from citrate‐sulfate solutions
Authors: Van Vy Uong , Thang Le Ba , Huong Nguyen Thi Thanh , Que Le Xuan
Published: March 2024

The effect of stabilizing and brightening additives, temperature and stirring on electrodeposited kinetics of NiCu alloy has been studied by the linear polarization method. The additives almost do not affect on the electrochemical reduction rate of Cu2+ ions, however it has a much affect on the reduction rate of Ni2+ ions. The presence of boric acids, saccharin or 1,4‐butynediol have increased cathode polarization, inhibited precipitation alloy and shifted discharge potential of Ni2+ about 100 to 150 mV towards more negative. The solution temperature strongly affected on the polarization curve over the full range of investigated electrode potential, the cathode current increased about 1.5 times when the temperature increases from 30 to 50 oC. The stirring did not increase the discharge current of Ni2+ ions, on the contrary, it significantly increased the discharge current of Cu2+ ions, increasing from 2 to 3 times compared to when did not stir.
A New Approach for the Synthesis of Sotolon in Racemic and Enantioenriched Forms
Authors: Trang Bui Thuy , Thuong Cao Hai , Thao Pham Xuan , Mac Dinh Hung , Grée Rene
Published: March 2024

Sotolon (3‐hydroxy‐4,5‐dimethyl‐2(5H)‐furanone) has been synthezised both in racemic and enantioenriched forms by a short sequence involving intramolecular tandem isomerization‐aldolisation and tandem izomerization/Mannich reactions as key steps. Optically active Sotolon has been obtained by using (S)‐N‐tert‐butane sulfinimine as a chiral starting material.
Dye removal using cashew nut shell activated carbon
Authors: Khang Dinh Sy , Hai Tran Duy , Thi Ta Dinh , Tuan Phan Dinh
Published: March 2024

Activated carbon prepared from agricultural byproducts and wastes could be used as an absorbent for dye removal from aqueous solution. Moreover, Vietnam has presently become one of the world's biggest cashew processing countries. Cashew nut shell has been considered as a hazardous solid waste. The wasted cashew nut shell should be used as a low cost source of activated carbon absorbent. The main approaches of this study are to optimize the conditions of activated carbon production from cashew nut shell and understand the adsorption mechanism of how the dye absorb onto cashew nut shell activated carbon. The absorption model developed in this study could be useful guide for assessing the independent impacts as well as the interactions between the impact parameters and give a good idea to enhance the absorption capacity. The experimental data was fitted well to the pseudo‐first and pseudo‐second order as well as the Elovich model at different initial MB concentrations. The inconsistence of the best‐fit‐kinetic model might result in difficulties in comprehensive understanding of adsorption mechanism. Other impacts, such as competitions of components, particle size could be included in next studies to develop the absorption models of the specific activated carbon prepared from cashew nut shell.
Directly Purification of Ostruthin from Paramignya trimera roots by CPC (centrifugal partition chromatography)
Authors: An Tran Chieu , Ngoc Pham Hong , Sang Pham Minh , Truc Pham Ngoc , Tien Nguyen Huynh Thuy , Nhu Tran Phan Huynh , Tam Phan Thi Thanh , Hung Le Ngoc , Van Trung Phung
Published: March 2024

Ostruthin was successfully isolated from the extract of Paramignya trimera (Oliver) Burkill roots by centrifugal partition chromatography (CPC) in one run. The two‐phase solvent system composed of n‐hexane‐ethyl acetate‐methanol‐water (2:1:2:1 v/v) in ascending mode (the upper organic phase was the mobile phase), with flow rate of 8.0 (mL/min) and rotation speed of 1600 rpm, was used. The purity of the ostruthin after isolation is 97.5 % confirmed by HPLC‐DAD at 320 nm. The present study highlights the ability of a CPC system to obtain high purity ostruthin directly from the P. trimera roots ethyl acetate extract.
Synthesis of 2‐(3‐methyl‐5‐oxo‐4,5‐dihydro‐1H‐pyrazol‐1‐yl) quinazolin‐4(3H)‐one derivatives
Authors: Bireddy Srinivasa Reddy , Rafeeq Mohammad , Chittireddy Venkata Ramana Reddy
Published: March 2024

A simple, synthesis of 2‐(3‐methyl‐5‐oxo‐4, 5‐dihydro‐1h‐pyrazol‐1‐yl) quinazolin‐4(3H)‐one 6(a‐d) derivatives, an easy, clean, and economical methodology has been defined. The development of a new pathway for the preparation of substituted derivatives of Quinazoline Pyrazole is highlighted in this report. The mild, inexpensive polyphosphoric acid has proven to be an effective catalyst for excellent yields in the above multi‐component reaction. Widely available and mostly benign catalyst and easy purification are among the several attractive features.
Optimization of silver nanowire synthesis for flexible transparent conductive electrodes
Authors: Nhan Nguyen Thanh , Linh Pham Duy , Dat Doan Tien , Cho Min Ju , Choi Dong Hoon , Ha Hoang Mai
Published: March 2024

In this work, a range of factors was investigated for the synthesis of silver nanowires. Nickel chloride showed to be a promising controlling agent for the scale‐up synthesis of silver nanowires. Other factors such as reaction temperature, concentrations of surfactant, precursor, controlling agent, and the effect of degassing were studied and optimized. The synthesized silver nanowire sample was applied for flexible electrode fabrication. The fabricated electrode showed to have high transparency (90 %), low sheet resistance (26 Ω/sq), low surface roughness (Rq = 6 nm), and high bending stability (withstand 100 bending cycles at bending radius of 4 mm), which satisfied the requirement for applications in flexible optoelectronic device.
Effect of different polarity solvents on the anti‐inflammatory activity of Symplocos cochinchinensis leaves and correlation with total polyphenol content
Authors: Trieu Ly Hai , Trang Le Vu Khanh , Minh Nguyen Thai , Dao Phan Thi Anh
Published: March 2024

Symplocos cochinchinensis leaves known as Vietnamese traditional herbal medicines which have been utilized anciently to support the medication of infirmities. The study aimed to explore the correlation of total polyphenol content (TPC) with anti‐inflammatory activity of S. cochinchinensis leaves. S. cochinchinensis leaf extracts (ethanol extract, chloroform, ethyl acetate, n‐butanol, aqueous fractions) was determined the TPC by Folin‐Ciocalteu reagent, anti‐inflammatory proficiency by in vitro protein denaturation and membrane lysis assays. The correlation between TPC and anti‐inflammatory activities was analyzed in silico by Pearson's method. Results illustrated that the TPC was arranged in sort of descending order as ethyl acetate fraction > n‐butanol fraction > ethanol fraction > aqueous fraction > chloroform fraction. S. cochinchinensis leaf extracts exhibited anti‐inflammatory effect via their protein denaturation inhibition capacity as well as hemolysis by heat and hypotonicity, which was better than the standard drug diclofenac sodium. There was a significantly negative correlation between TPC in S. cochinchinensis leaf extracts with their IC50 inhibition of protein denaturation, hemolysis by heat and hypotonicity with Pearson's correlation coefficient (r) of ‐0.6302, ‐0.7241, and ‐0.9101, respectively. It was suggested that S. cochinchinensis leaves have great potential for anti‐inflammatory activity during the high total polyphenol content. Hence, polyphenol compounds of S. cochinchinensis leaves should be considered since they can have good effects when in pure form.
Chrysin flavonoid adsorbed on B12N12 nanocage ‐ A novel antioxidant nanomaterial
Authors: Khalili Atefeh , Baei Mohammad T. , Ghaboos Seyed Hossein Hosseini
Published: March 2024

Antioxidative activity of chrysin (CYS) on the B12N12 nanocage has been evaluated by density functional theory with B3PW91‐D3 and M06‐2X‐D3 methods. Adsorption behavior and study of topologies demonstrated that the CYS has chemisorbed to the nanocage and shows notable changes in the electronic properties of B12N12. The antioxidant properties of the CYS and CYS/B12N12 systems have been studied in the different environments by the M06‐2X‐D3 method. The findings demonstrated that in the vacuum phase and water, benzene, and ethanol solvents, the BDE (5O‐H), PDE, PA values of CYS/B12N12 are smaller than those of CYS system. The current study implied that B12N12 nanocage can increase the antioxidative properties of the CYS.
Triterpenoids from Macrosolen bidoupensis Tagane & V.S. Dang whole plant
Authors: Hung Le Kieu , Chi Huynh Bui Linh , Tuyen Pham Nguyen Kim , Trang Nguyen Thi Thuy , Van Son Dang , Mai Tran Thi Ngoc , Ky Nguyen Diep Xuan , Dat Bui Trong , Minh Phan Nhat , Tri Mai Dinh , Phat Nguyen Tan
Published: March 2024

From the whole plants of Macrosolen bidoupensis Tangane & V.S. Dang, five triterpenoids, 24‐methylenecycloartanol (1), (23Z)‐cycloart‐23‐en‐3β,25‐diol (2), mollic acid (3), ursolic acid (4), 3β‐hydroxyurs‐11‐en‐28,13‐olide (5), together with two compounds, one C11‐norisoprenoid, loliolide (6), and one lignan, syringaresinol (7) were determined by using HR‐ESI‐MS, and NMR assignments. For the first time all compounds except 2 were clarified from the genus Macrosolen, whereas, compound 2 was verified from this species.
Overview on biodiesel market
Authors: Datta Indukamal , Ghosh Aniruddha , Acharjee Animesh , Rakshit Atanu , Saha Bidyut
Published: March 2024

The abundance of fossil fuel resources has been steadily declining since it was emerged on the Earth. As a renewable energy source, great importance has been provided to biodiesel and consequence to the factor it gains from the ascending fossil fuel price and its potential environmental amenities. The present report concerns some of the interesting spectacular studies for the global biodiesel market to ameliorate as an alternative fuel, while describing many advantages, challenges and future aspects of the biodiesel market.
Highly efficient in‐situ sulfur doped graphitic carbon nitride nanoplates as an artificial photosynthetic system for NADH regeneration
Authors: Gupta Sarvesh Kumar , Gupta Abhishek Kumar , Yadav Rajesh Kumar , Singh Ajeet , Yadav B. C.
Published: March 2024

Photocatalysis reduces the challenges associated with power activities by the conversion of solar energy into chemical energy. Herein, sulfur‐doped graphitic carbon nitride nanoplate (S‐g‐CN‐NP) via polycondensation and vapor oxidative treatment methods as a promising solar light‐reactive photocatalyst has been designed. The photo‐mediated reduction of NAD+ is used to facilitate the extremely efficient solar light‐driven photocatalytic selective production of nicotinamide adenine dinucleotide (NADH). The S‐g‐CN‐NP photocatalyst shown excellent optical and photoelectrical properties, supporting an NADH yield of (97±0.010 %), which was 1.5 folds higher than that of S‐g‐CN powder (65±0.012 %). Through the transformation of S‐g‐CN powder to nanoplates, the improvement of photocatalytic in S‐g‐CN‐NP was primarily ascribed to the growth of active sites of the nanoplates. The current study focuses on the creation and use of an S‐g‐CN‐NP photocatalyst for direct selective NADH regeneration under solar light.
Study on effects of isocyanate on some properties of epoxy varnish
Authors: Thanh Nguyen Trung
Published: March 2024

This article presents effect of toluene diisocyanate (TDI) as a curing agent on mechanical properties, drying time, chemical resistance, thermal oxidation stability of epoxy varnish coating. When TDI content raises from 3 to 11 weight percent (wt.%), relative hardness increases from 0.45 to 0.74 while adhesion, flexural strength, impact resistance down from 1 point, 2 mm, 200 Kg.cm to 2 points, 4 mm and 180 Kg.cm respectively. TDI content increases from 3 to 11 wt.%, grade 3 drying time of coating decreases rapidly, however, when TDI content reaches 11 wt.%, air bubbles appear. In addition, influence of TDI on chemical conditions, thermal oxidation stability of coating was also introduced.
Evaluating natural product compound inhibitors of SARS‐CoV‐2 main protease and spike protein target by molecular docking approach
Authors: Tung Bui Thanh , Nhung Nguyen Hong , Hang Ta Thi Thu , Linh Vu Khanh , Ngoc Le Minh
Published: March 2024

Spike protein plays a significant role in viral transmission, while main protease's role is in the replication of the virus. In this study, we screened in silico natural products compounds activity to inhibit two targets of spike proteins and main proteases. Our data were compared with hydroxychloroquine and X77, which have been demonstrated inhibitory activity of these targets, respectively. Our results showed that 12/59 compounds have a higher ability to inhibit main protease than X77 and 59/59 compounds have a higher ability to inhibit spike protein than hydroxychloroquine. Notably, four compounds with the most strongly inhibitory activity of main protease are amentoflavone, punigluconin, amarogentin, emblicanin A. We found seven compounds with the most powerful inhibitory ability of spike protein are amentoflavone, hesperidin, rutin, glycyrrhizin, myricitrin, puerarin, daidzein. Among these compounds, ADMET profile and Lipinski's rule of five criterion analysis suggested four compounds including amentoflavone, myricitrin, purerarin and daidzein have drug‐likeness properties. Interestingly, amentoflavone is the natural compound with the highest inhibitory ability for main protease and spike protein, which may be further explored as anti‐SARS‐CoV‐2 agents.
In‐situ prepared S‐doped covalent melem framework as a photocatalyst with improved photocatalytic responses under solar light illumination
Authors: Singh Chandani , Yadav Rajesh K. , Kim Tae Wu
Published: March 2024

Melem (M) is an emergent metal‐free material due to its nature abundance and easy preparation. Synergetic escalation of band gap generation and charge transfer of M to increase solar chemical synthesis ability remains a hot challenging topic yet. Herein, we designed first time in‐situ prepared sulfur‐doped covalent melem‐based frameworks (S‐CMFs) photocatalyst for NAD(P)H regeneration and 1,3‐oxathiolane‐2‐thiones production under solar light irradiation. S‐CMFs photocatalyst shows excellent photocatalytic stability and activity over the pristine CMFs and M. The presence of sulfur in frameworks drastically improved the photocatalytic efficiency of S‐CMFs due to its unique properties such as enhanced the solar light adsorption ability, molar extinction coefficient, slow charge recombination, fast charge separation and transportation of solar light to generate electrons‐holes. Hence, S‐CMFs photocatalyst has a vital role in the regeneration of NADH and NADPH with 54.84 and 51.05 % catalytic efficiencies and ~ 99 % for yields and selectivity of 1,3‐oxathiolane‐2‐thiones under solar light. This study demonstrates that the Z‐scheme hetero junction and photocatalytic reaction using S‐CMFs would be a suitable route for the production of solar fuel via artificial photosynthetic system.
Extraction of cynarine and chlorogenic acid from Artichoke leaves (Cynara scolymus L.) and evaluation of antioxidant activity, antibacterial activity of extract
Authors: Thang Nguyen Quoc , Hoa Vo Thi Kim , Van Tan Le , Tho Nguyen Thi Mai , Hieu Tran Quang , Phuong Nguyen Thi Kim
Published: March 2024

Artichoke has been well known as a traditional medicine because of its phenolic compounds. In this study, solid‐liquid extraction, ultrasound‐assisted extraction, and enzyme‐assisted extraction were used to extract cynarine and chlorogenic acid from dry artichoke leaves. In the optimum experimental parameters: Enzyme concentration of 5.2 U/mL, pH of 4.6, and incubation of 29°C, the yield of cynarine and chlorogenic acid were determined to be 156.3 ± 2.3 mg/kg, and 19.8 ± 1.4 mg/kg of dry material, respectively, which were not significantly with the predicted value (154.5 mg/kg for cynarine, 19.4 mg/kg for chlorogenic acid). The artichoke leaves pectinase enzymes extract was studied antioxidant activity via DPPH and FRAP analysis. The IC50 was obtained in the artichoke extracts that showed the value of 30.0 mg/L for DPPH and 77.8 mg/L for FRAP. The artichoke extract was also studied antibacterial activity. The inhibition zones were 12 mm against Bacillus cereus at 50 mg/mL artichoke extract and 8 mm against Escherichia coli and Pseudomonas aeruginosa at 100 mg/mL artichoke extract. The artichoke extract using pectidase enzymes was high cynarine and chlorogenic acid which could have applications to diseases caused by oxidative damage and antibacterial damage.
Study on characteristics of thermoplastic starch based on Vietnamese arrowroot starch plasticized by glycerol
Authors: Van Khoi Nguyen , Tung Nguyen Thanh , Ha Pham Thi Thu , Trang Pham Thu , Duc Nguyen Trung , Thang Tran Vu , Phuong Hoang Thi , Huong Nguyen Thu , Phuong Nguyen Thi Lien
Published: March 2024

In this study, glycerol was used as plasticizer for the preparation of thermoplastic starch (TPS) from arrowroot starch (AS). Samples with different contents of glycerol (10, 20, 30 and 40 %wt) were prepared by extrusion technique. The properties of TPS were tested by analysis method. The FTIR, SEM and XRD data showed that the structure of arrowroot starch completely changed after extrusion process with the presence of glycerol at high temperatures. TPSs were plasticized and the relationship between plasticization degree and TPS properties was characterized and described by mechanical properties. The experimental results also showed that the tensile strength slightly decreased and the elongation at break significantly increased with the increase of the degree of plasticization.
Structural analysis and chemical descriptors analysis of 4‐aminopyridine adsorbed on M4 (M = Co, Ni, Cu) clusters: A DFT study
Authors: Pahuja Anushka , Jeyakumar Thayalaraj Christopher , Paularokiadoss Francixavier
Published: March 2024

The geometrical properties of 4‐Aminopyridine and the transition metal clusters M4 (M = Co, Ni and Cu) adsorbed 4‐Aminopyridine were examined using DFT/B3LYP/6‐31G*/LANL2DZ. The reactivity descriptors were thoroughly examined to determine which cluster had the best biological potential for adsorption. This molecule's bioactivity may be predicted using wavefunction‐dependent qualities such as the ones found in research such as the ones conducted using algorithms such as ALIEE, LOLE, LIE, ELF, RDG, and the NCI. The molecule has relevant adsorption energy on the surface of the metal clusters M4 (M = Co, Ni, and Cu).
Biological synthesis and characterization of zinc oxide nanoparticles (ZnONPs) from Anisomeles malabarica
Authors: Sekar Alagan , Murugan Palaniyapillai Jothi , Paularokiadoss Francisxavier
Published: March 2024

In nanotechnology, the economic and ecological friendly synthesis of novel nanoparticles of natural structures particularly extracts of plant parts has come to be a rising field. The leaf extract of Anisomeles malabarica was used as a novel reducing agent to make zinc oxide nanoparticles (ZnONPs) from zinc acetate dihydrate. This study has been employed for two different concentrations of plant extract (1 and 3mL) as starting precursors. The formation of NPs was studied using X‐ray diffraction, UV‐visible, and Fourier transformed infrared spectroscopy. The size distribution and morphology of the synthesised nanoparticles were studied using scanning electron microscopy. The peak at 350 nm in the UV‐Vis spectra indicates its high excitation binding strength. The AFM study aimed to determine the shape and size distribution of nanoparticles, while FTIR studies confirmed the existence of biomolecules.
Preparation of injectable free‐HRP‐mediated and self‐catalyzed gelatin‐tyramine hydrogel for biomedical applications
Authors: Nguyen Ngoc Hao , Bui Quynh Anh , Dang Le Hang , Nguyen Dinh Trung , Tran Ngoc Quyen
Published: March 2024

Approaches of synthesizing injectable hydrogels have drawn significant attention in several fields including drug delivery, tissue adhesion, and wound healing. Among them, injectable horseradish peroxidase‐mediated hydrogels have emerged as a prospective candidate in the development of biomedical materials. In the study, we prepared a hematin‐gelatin‐tyramine (HGT) polymer which could be exploited to prepare an injectable hydrogel in absence of Horseradish peroxidase (HRP). The chemical structure of HGT was characterized by UV‐Vis, 1H‐NMR spectroscopies. The HGT hydrogel could be formed in situ rapidly in presence of a small amount of H2O2 (3‐15 mM). Besides, HGT can catalyze pyrogallol and guaiacol like the enzyme HRP, and HGT has good biodegradability. Further studies on the biocompatibility of hydrogels will be investigated towards tissue regeneration.
Chemical constituents of marine sponge Ianthella basta (Pallas, 1766)
Authors: Hang Dan Thi Thuy , Thung Do Cong , Trang Do Thi , Yen Pham Hai , Cuc Nguyen Thi , Dung Duong Thi , Tai Bui Huu , Nhiem Nguyen Xuan , Van Kiem Phan
Published: March 2024

Phytochemical study on the methanol extract of the elephant ear sponge Ianthella basta (Pallas, 1766) led to the isolation of one new (named lanthebastanoside A, 1) and nine known compounds, holothurin A2 (2), desulfoechinoside A (3), echinoside B (4), holothurin A (5), holothurin B (6), adenine (7), adenosine (8), thymidine (9), and thymine (10). The chemical structures of compounds 1‐6 were elucidated by extensive spectroscopic analyses including HR‐ESI‐MS, 1D and 2D NMR, and by comparison of the spectral data with those of previously reported data. Compounds 7‐10 were identified by 1H NMR data and comparing their retention times with authentic samples by HPLC analysis. This is the first report of compounds 2‐6 from marine sponge.
DFT investigations on conformational analysis, solvation effects, reactivity studies, chemical descriptors and docking of two anti‐cancerous drugs, Lenvatinib and Regorafenib
Authors: Al‐Otaibi Jamelah S. , Ullah Zakir , Mary Y. Sheena , Mary Y. Shyma , Soman Sreejit , Thirunavukkarasu M. , Kwon Hyung Wook
Published: March 2024

Two anticancer drugs, lenvatinib (LNTB) and regorafenib (RGFB) are evaluated for their solvent effects, wavefunction reactivity properties and different chemical descriptors by means of theoretical methods. Potential energy surface scan studies about all possible rotable bonds are performed and lowest energy conformations of LNTB and RGFB are for the torsion angles C25‐C24‐C29‐N9 and C25‐N10‐C15‐C21. Reactive sites are O and N, H atoms, giving nucleophilic and electrophilic attacks for both the molecules. Solvation free energies are calculated in different solvents and all solvents are suitble except heptane. Electron densities of LNTB and RGFB show that closed‐shell interactions are in different regions. The intramolecular hydrogen bonds of the compounds LNTB and RGFB are found at O2‐H38, Cl1‐H37 & O5‐H47 and F2‐H38, N11‐H45, O7‐H35 & O7‐H37, respectively. Due to anticancer activities, LNTB and RGFB are docked with different proteins which give binding affinities from ‐8.4 to ‐10.5 for RGFB and ‐7.9 to ‐10.1 kcal/mol for LNTB.
A review of silver‐dopped graphene oxide nanocomposite: Synthesis and multifunctional applications
Authors: Thinh Doan Ba , Dat Nguyen Minh , Tuyen Nguyen Ngoc Kim , Tai Le Tan , Hai Nguyen Duy , Tinh Ninh Thi , Huong Le Minh , Do Dat Tran , Huong Quach Thi Thanh , Nam Nguyen Thanh Hoai , Oanh Doan Thi Yen , Phong Mai Thanh , Hieu Nguyen Huu
Published: March 2024

In recent years, the applications of nanomaterials are getting more common in commercial products. Amongst them, silver nanoparticles (AgNPs) are the most well‐known nanomaterials for their outstanding antibacterial properties and potential applications in the biomedical field. The agglomeration of AgNPs due to their high surface energy has diminished the actual antibacterial applications of these plasmonic nanoparticles. To tackle this problem, the AgNPs are grafted onto graphene oxide (GO) sheets (Ag/GO) to minimize the agglomeration of AgNPs and enhance the extraordinary antibacterial characteristics of AgNPs thanks to several outstanding features of GO. Ag/GO composite also exhibits other properties such as good optical sensitivity to trace heavy metal ions, adsorption affinity, and catalytic activity for the removal of organic compounds. With all the possibilities, Ag/GO can be considered a multifunctional nanocomposite that can be applied in various fields such as biomedical treatment and environmental remedy.
Enhancing radical scavenging activity of Cordyceps militaris extract by gamma irradiation
Authors: Quynh Tran Minh
Published: March 2024

Nowadays, irradiation treatment has been well‐known as an effective tool to eliminate the pathogenic and spoilage microorganisms existing in foods and food ingredients in order to ensure their hygiene and extend their shelf‐life. In the present study, the dried fruiting bodies of Cordyceps militaris were irradiated under gamma source at Hanoi Irradiation Center, then extracted to collect crude polysaccharides and to evaluate the effects of gamma ray on antioxidant properties and functional groups of bioactive components in the extract (CME). Our preliminary results showed the antioxidant ability of CME, which is presented by DPPH radical scavenging activity, increased with concentration and radiation dose. The concentration required to induce 50 % antioxidant activity or median inhibition concentration (IC50) of CME decreased with radiation dose, and the smallest SC50 obtained with the CME irradiated at 15 kGy. These results suggested that the antioxidant capacity of CME can be much improved by irradiation. However, gamma radiation insignificantly affected the functional groups of CME as analyzed with Fourier transform infrared (FT‐IR) spectroscopy although the intensities of some characteristic peaks were distorted by high dose radiation.
Phenolic glycosides from the peels of durian fruits Durio zibethinus L.
Authors: Cuong Dang Viet , Hanh Tran Thi Hong , Huong Nguyen Thi , Huong Pham Thi Mai , Quang Tran Hong
Published: March 2024

In the present study, six phenolic glycosides, including one new durianol F (1) and five known compounds, durianol A (2), syringaresinol glucoside (3), 4‐O‐β‐glucopyranosyl sinapic acid methyl ester (4), quercetin‐3‐glucopyranoside (5), and quercetin‐3‐rhamnopyranoside (6) were isolated from a methanol extract of the peels of durian fruits (Durio zibethinus). Their chemical structures were elucidated using the NMR and MS spectroscopic analyses and comparision with the previously reported values. In addition, their cytotoxic effect against three human carcinoma cell lines, including liver (HepG2), breast (MCF7), and lung (SK‐LU‐1) was also evaluated.
Co2+ and Cr3+ ions removal from wastewater by using nanostructural hydroxyapatite
Authors: Phuong Nguyen Thu , Thom Nguyen Thi , Nam Pham Thi , Van Trang Nguyen , Huong Tran Thi Thu , Hai Do Thi , Thu Le Phuong , Osial Magdalena , Thanh Dinh Thi Mai
Published: March 2024

Due to the growing pollution of the environment, water purification methods have to be improved. One of the most effective solutions is the removal of heavy metal ions by porous materials, including hydroxyapatite. Lao Cai Province in Vietnam has a tremendous reservoir of apatite ore that can be a precursor for nanostructural materials. In this paper, we refer to the recent studies on removing heavy metal salts, including the cobalt and chromium ions, from the wastewater by the nanostructural hydroxyapatite obtained from the apatite ore gained in the Lao Cai Province. The measurements were performed according to the pH, mass of the adsorbent addition into the real wastewater solution, and time exposition onto the adsorbent; and the suitable condition is a dose of modified apatite of 1 g/L; contacting time of 60 minutes and 6 g/L and 15 minutes in the pH range from pH0 (3.76 and 6.57) to neutral pH corresponding to Cr3+ and Co2+. We show that just a small amount of the nanostructural hydroxyapatite can work efficiently to remove the chromium and cobalt ions from the solution with maximum adsorption capacity is 70.37 mg/g and 13.52 mg/g, respectively.
Green synthesis of pectin‐silver nanocomposite: Parameter optimization and physico‐chemical characterization
Authors: Nhi Tran Thi Y , Thien Do Truong , Cong Trinh Duc , Tung Ngo Trinh , Thuy Lai Thi , Thuc Nguyen Thi , Nu Tran Thi , Dat Nguyen Dang , Hileuskaya Kseniya , Kalatskaja Joanna , Kulikouskaya Viktoryia
Published: March 2024

In our present reports, an eco‐friendly approach of green‐synthesis of silver nanoparticles without using any toxic reducer or organic solvent was investigated. Pectin, a biopolymer, was used both as a reducing agent and a stabilizer. Response surface methodology (RSM) was carried out with four parameters: pectin concentration, AgNO3 concentration, temperature, and time to obtain the minimum mean particle size of silver nanoparticles (response Y). The optimal conditions were pectin concentration of 1.64 mg/ml, silver nitrate of 3.26 mM, temperature of 36.6°C and time of 9.6 h. A silver particle size of 6.82 nm was obtained by Design Expert Software and silver particle size obtained experimentally was 6.62 nm. The physico‐chemical properties of the pectin‐silver nanocomposite were characterized by combined techniques including visible ultraviolet spectroscopy (UV‐Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), infrared spectra (IR), and X‐ray diffraction.
Ethanolic extract of Chrysophyllum albidum leaves and peels as a green inhibitor for AISI 1015 carbon steel in 1M H2SO4 solution
Authors: Dauda K. T. , Owoeye T. F. , Fayomi O. S. I. , Akande I. G.
Published: March 2024

The degradation of mild steel has been an issue of concern in most industries. Because of this challenge, mild steel (AISI 1015 carbon steel) was inhibited using ethanolic extract from leaves and peels of Chrysophyllum albidum (C. albidum) in 1 M H2SO4 was investigated using gravimetric (weight loss), gasometric and potentiodynamic polarization (PP) methods. Samples of mild steel were placed in an acidic medium and tested at different concentrations of extract. The PP experiment indicated that the inhibition efficiency (I.E) of C. albidum ranges from 70.9‐85.9 % and 54.6‐89.1 %, for leaves and peels extract, respectively. The I.E increases with increase in concentration of the extracts due to the adsorption of their molecules on the mild steel surface. The leaves and peels 1.5 g/L extract inhibited mild steel sample exhibited a significant corrosion rate of 0.0821 mm/year and 0.0635 mm/year, respectively. The inhibitors exhibited mixed‐type corrosion inhibition tendencies. Moreover, the weight loss test revealed that the inhibitors lower the corrosion rate of the steel samples. The adsorption ability of the extracts was approximated through the Langmuir isotherm. The correlation regression coefficients (R2) values of 0.9960 and 0.9981 were observed for the leaves and peels extracts, respectively. This study has shown that C. albidum extracts reduced the rate at which mild steel corrodes in an acidic medium. It is therefore recommended for application in acidic media.
A new lignanamide from the stems of Derris elliptica (Wall.) Benth with antimicrobial and anti‐inflammatory activities
Authors: Trang Bui Thi Thu , Huong Phan Thi Thanh , Anh Nguyen Tuan , Huong Nguyen Thi , Linh Nguyen Thi Thuc , Van Kiem Phan , Nhiem Nguyen Xuan
Published: March 2024

A new lignanamide, named derristicine A (1), together with ten known compounds, dalbin (2), wistin (3), 3,5‐dimethoxy‐4‐hydroxy‐1‐O‐β‐D‐glucopyranoside (4), 3,4,5‐trimethoxyphenyl‐1‐O‐(4′‐sulfo)‐β‐D‐glucopyranoside (5), vanillic acid glucosyl ester (6), (9R)‐roseoside (7), (9S)‐roseoside (8), pumilaside A (9), (8R,8′R)‐secoisolariciresinol‐9‐O‐β‐D‐glucopyranoside (10), and (8S,8′S)‐secoisolariciresinol‐9‐O‐β‐D‐glucopyranoside (11) were isolated from Derris elliptica (Wall.) Benth stems. Their chemical structures were determined by analysis of HR‐ESI‐MS, NMR spectral data, as well as comparison with previous reports. Compounds 2‐3, 5‐8, and 10 showed potential inhibitory effect on the growth of Candida albicans strain with a MIC value of 37.5 μM. Compounds weakly inhibited NO production in LPS activated RAW264.7 cells.