bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinetics and isotherm studies for adsorption of arsenic on ferric hydroxide by potentiostatic electrocoagulation
Authors: Binh Phan Thi , Van Anh Nguyen Thi , Thuy Mai Thi Thanh , Xuan Mai Thi 
Published: February 2020

AbstractThe potentiostatic electrocoagulation (PEC) using iron (CT3 steel) for anode material was applied to removal of arsenic from well water. Some parameters such as potential, electrolysis time, and initial arsenic concentrations were varied for research in this article. The arsenic concentrations before and after PEC processing were analysed by AAS method. The mass of ferric hydroxide was calculated via Faraday's law. The results showed that the residual arsenic concentration in water samples from initial arsenic concentration until 800 ppb is smaller than that of WHO requirement (10 ppb). The adsorption of arsenic on ferric hydroxide fitted well into pseudo second‐order kinetic equation, where its equilibrium adsorption capacity was linearly depended on the initial adsorption rate with R2 of 0.9864. The Langmuir parameters Nmax and KL were 23.58 mg/g and 1060 L/mg with correlation constant (R2) of 0.827, respectively.
Pregnane glycosides from Gymnema sylvestre
Authors: Yen Duong Thi Hai , Thu Vu Kim , Tai Bui Huu , Yen Pham Hai , Nhiem Nguyen Xuan , Kiem Phan Van 
Published: February 2020

AbstractThree pregnane glycosides, gymnepregoside F (1), 12‐O‐(E)‐cinnamoylgymnepregoside F (2), and stephanoside I (3) were isolated from the leaves of Gymnema sylvestre (Retz.) R.Br. ex Schult. Their structures were identified on the basis of spectroscopic evidences and in comparison with those reported in the literature. All these compounds were reported from this genus Gymnema for the first time.
Rapid and efficient treatment of wastewater from fish sauce‐manufacturing factories by using the electrochemical oxidation process
Authors: Minh Bui Quang , Long Nguyen Nghia , Van Hien Pham , Dung Nguyen Tuan 
Published: February 2020

AbstractWastewater from fish sauce‐manufacturing Phung Hung Ltd. Company with high salinity has been treated applying the electrochemical oxidation process, using a Ti/CeO2‐Pt anode and different cathodes: copper, stainless steel and copper‐zinc alloy. The pH value and the applied current density have been also examinated. All three cathodes can be used for the organic pollutant electro‐oxidation, however Cu/Zn cathode exhibits a higher efficiency on by‐product nitrate removal. The investigation on the pH and current density showed that the electro‐oxidation process was favorably occurred at pH8 and 30 mA/cm2. After 60 min of electrolysis, ammonia, total nitrogen and COD can be discharged into the A column level of QCVN/11‐2015/BTNMT.
Effect of heating treatment on structure and bioactivity of sol‐gel bio‐glass
Authors: Vuong Bui Xuan 
Published: February 2020

AbstractThe purpose of this work is to investigate the effect of heating treatment on the structure and bioactivity of the 58S bio‐glass. Phase composition analyzed by XRD and FTIR techniques indicates that the sample heated at 700°C produced an amorphous state while the ones heated at 900 and especially 1100°C resulted in two crystalline phases of CaSiO3 and Ca3(PO4)2. The in vitro experiment was carried out for the 58S bio‐glass sample heated at 1100°C by soaking the powder sample in the SBF solution at different times. The XRD result confirms that the heating treatment inhibited the bioactivity through the slower formation of hydroxyapatite layer on the surface of sample after immersion. The specific area and surface morphology of heating sample were also evaluated by BET and SEM measurements.
Study on the interaction between [Pt(μ‐Cl)(isopropyl eugenoxyacetate‐1H)]2 and 1,3‐diisopropylbenzimidazolium bromide
Authors: Thong Pham Van , Thang Nguyen Manh , Chi Nguyen Thi Thanh 
Published: February 2020

AbstractThe interaction between the dinuclear chelate ring complex [Pt(μ‐Cl)(iPrEug)]2 (1) (iPrEug: deprotonated isopropyl eugenoxyacetate) and 1,3‐diisopropylbenzimidazolium bromide (iPr2‐bimy·HBr) has been studied for the first time. The result shows that the chloride bridges in 1 are easily cleaved by the iPr2‐bimy in the present of base to form a mixture (Phh) of two complexes [PtBr(iPrEug)(iPr2‐bimy)] (2) and [PtCl(iPrEug)(iPr2‐bimy)] (3), and the molar ratio of 2:3 in Phh depends on the used base Ag2O or Na2CO3/NaOOCCH3/NaHCO3/NaOH. The reaction of Phh with NaBr afforded complex 2 with high yield. The structure of 2 was determined by weight method, ESI‐MS, IR, 1H NMR, 13C NMR, HSQC spectroscopies and single‐crystal X‐ray diffraction. The NMR and XRD studies also reveal that the introdution of iPr2‐bimy leads to a weakening of the Pt‐(C9=C10) bond and strengthening of the Pt‐C5 bond in 2.
Possible detection of antibiotic residue using molecularly imprinted polyaniline‐based sensor
Authors: Vu Van‐Phu , Tran Quang‐Thinh , Pham Duc‐Thanh , Tran Phu‐Duy , Thierry Benjamin , Chu Thi‐Xuan , Mai Anh‐Tuan 
Published: February 2020

AbstractMolecular imprinted polymer (MIP) nanowires were deposited on a gold electrode by electro‐polymerization using aniline monomer as reagent and chloramphenicol (CAP) as template molecules. The molecular template was then electrochemically removed to generate the cavities on the polyaniline matrix that enables a specific recognition of CAP. The morphology, structure and electrochemical properties of the MIP were characterized by SEM, FT‐IR and cyclic voltammetry. The initial results show that the MIP sensor can detect 10‐7 mM of CAP and the limit of detection could be lower by performing recommended study.
Polyoxygenated polyketides from the marine‐derived fungus Aspergillus micronesiensis
Authors: Luyen Nguyen Dinh , Huong Le Mai , Ha Tran Thi Hong , Cuong Le Huu , Yen Duong Thi Hai , Tai Bui Huu , Nhiem Nguyen Xuan , Van Kiem Phan 
Published: February 2020

AbstractUsing combined chromatographic methods, seven compounds as epicoccolide A (1), epicoccolide B (2), 2‐O‐methylbutyrolactone II (3), NC3B (4), epicoccone B (5), (22E,24R)‐5α,8α‐epidioxy‐24‐methyl‐cholesta‐6,22‐dien‐3β‐ol (6), and 4‐hydroxybenzaldehyde (7) were isolated from the marine‐derived fungus Aspergillus micronesiensis. Their chemical structures were determined by extensive analysis of HR‐ESI‐MS and NMR spectroscopy and comparison with those reported in the literature. All these compounds were isolated from Aspergillus micronesiensis for the first time. The seven compounds were assayed for their cytotoxic activity included Hep‐G2, LU‐1 and Vero cells. Compounds 1, 2, and 4 showed meaningful cytotoxic activity with the IC50 values ranging from 3.97 to 4.71 μg/mL against three tested cell lines comparing to the IC50 values ranging from 0.29 to 0.31 μg/mL of the positive control compound ellipticine.
Four flavonols form the whole plant of Nervilia aragoana
Authors: Mai Tran Thi Ngoc , Vy Do Phuong , Phat Nguyen Tan , Minh Phan Nhat , Tri Mai Dinh , An Tran Nguyen Minh , Huy Duong Thuc , Luan Tran Cong 
Published: February 2020

AbstractFour flavonols, including rhamnazin (1), nervilifordizin A, B (2, 3) and nervilifordin B (4) were isolated from the whole plant of Nervilia aragoana. All the compounds (1‐4) were found for the first time from this species. Their structures were elucidated by 1D, 2D‐NMR and compared with published data.
Sesquiterpenes from Fissistigma pallens (Fin. & Gagn.) Merr.
Authors: Thinh Ngo Sy , Thu Nguyen Thi Bich , Trang Do Thi , Van Kiem Phan , Tai Bui Huu , Nhiem Nguyen Xuan 
Published: February 2020

AbstractSeven sesquiterpenes, alismol (1), 4β,12‐dihydroxyguaian‐6,10‐diene (2), spathulenol (3), alismoxide (4), 10‐O‐methyl‐alismoxide (5), 1αH,5βH‐aromandendrane‐4β,10α‐diol (6), and 15‐hydroxy‐α‐cadinol (7) were isolated from the methanol extract of the leaves of Fissistigma pallens (Fin. & Gagn.) Merr. Their chemical structures were determined using NMR spectra as well as in comparison with the reported data. Compounds 1‐2 and 4‐7 were isolated from Fissistigma genus for the first time.
Secondary metabolites from marine actinomycete Streptomyces sp. G330
Authors: Van Hieu Tran , Ngan Truong Bich , Huong Doan Thi Mai , Quyen Vu Thi , Minh Le Thi Hong , Murphy Brian T , Van Cuong Pham 
Published: February 2020

AbstractEight compounds, 2,4‐dichloro phenyl 2,4‐dichloro benzoate (1), cyclo‐(Pro‐Trp) (2), cyclo‐(Pro‐Leu) (3), cyclo (Trp‐Ser) (4), cyclo (Trp‐Ala) (5), indol 3‐acetic acid (6), 3‐hydroxyacetylindol (7) and indol‐3‐carboxylic acid (8) were isolated and characterized from the culture broth of the marine actinomycete Streptomyces sp. G330 strain. Their structures were determined by spectroscopic analysis including MS, 1D and 2D NMR, as well as by comparison with reported data in literature.
Purification of titanium tetrachloride from titania slag chlorination
Authors: Hung Ly Cam , Hai Tran Duy , Khoa Tran Anh , Vien Le Minh , Tuan Phan Dinh 
Published: February 2020

AbstractPurification of titanium tetrachloride (TiCl4) is an important step in the titanium process. After chlorination, impurities in the gained crude TiCl4 such as V, Al, Fe, Si, etc. were removed by distillation technique following the chemical pre‐treatment method. Simple distillation, distillation with bubbled N2 and distillation in presence of copper metal were tested. Effect of copper metal, diethyl malonate and acetylacetone on the impurities removal was evaluated. Obtained results showed that the chemical pre‐treatment method exhibited a higher efficiency for TiCl4 purification than the distillation method. Acetylacetone was shown to be a suitable agent for impurities removal, resulting low content of V, Zr, Al, Fe and Si in the final purified TiCl4 product. Crude TiCl4 purification in distillation tower of a pilot scale was successfully operated.
Adsorption characteristics of hydantoin derivatives on mild steel surface in acidic medium: An experimental approach
Authors: Deepakumari H. N. , Revanasiddappa H. D. , Prasad K. N. N. 
Published: February 2020

AbstractHydantoin compounds tagged 3‐(3,3‐diethylureido)‐N‐(4‐hydroxyphenyl)‐2,4‐dioxoimi dazolidine‐1‐carbothioamide (3a) and N‐(4‐aminophenyl)‐3‐(3,3‐diethylureido)‐2,4‐dioxoimidazolidine‐1‐carbothioamide (3d) were studied for their ability to inhibit mild steel corrosion in 0.5 M HCl using gravimetric, potentiodynamic polarization, and electrochemical impedance techniques. Various thermodynamic parameters for the adsorption of these inhibitors on mild steel was computed and discussed. Scanning Electron Microscopy (SEM) analysis were carried out to characterize the surface film.
Influence of the weight ratio of an epoxy resin modified by castor oil and an epoxidiacrylate oligomer on photocrosslinking and properties of UV‐cured coatings
Authors: Hien Le Xuan , Thanh Do Minh , Tai Nguyen Huu 
Published: February 2020

AbstractThe influence of the weight ratio of a castor oil modified epoxy resin (CE) and an epoxidiacrylate resin (EDA) on photocrosslinking and properties of the coatings containing these resins, hexandioldiacrylate monomer (HDDA) and photoinitiator Darocur 1173 (D.1173) upon UV‐exposure have been studied. The variation of acrylate groups during the photoinitiated polymerization was evaluated by FTIR analysis. The crosslinking of the UV‐cured coatings was proved by gel fraction and swelling degree determinations. In addition, some of the properties of the UV‐cured coatings such as relative hardness, flexibility, impact resistance, adhesion onto steel plates and gloss have also been examined. It was shown that the increase of the CE/EDA ratio from 10/40 to 40/10 in investigated coatings led to the decrease of the conversion rate of acrylate groups, and significantly changed some properties of the cured coatings after 14.4 s of UV irradiation: Decrease of gel fraction from 96 to 61 %, but improved the flexibility from 10 to 3 mm, impact resistance from 40 to 140 kG.cm, adhesion from 5 to 2 points. The gloss of the coatings remained to be 100 % in all cases. Long hydrocarbon chains of castor oil residue in CE, lower reactivity of double bonds and radicals formed in the chains compared with those of acrylate groups have been attributed to the obtained relationship between the CE/EDA ratio and photocrosslinking, properties of the cured coatings.
Properties of polymer blends based on devulcanized waste rubber powder (d‐WRP)/EPDM/P
Authors: Dung Nguyen Tuan , Hanh Le Thi My , Lan Pham Thi , Minh Vu Xuan , Van Bien Tran 
Published: February 2020

AbstractIn this study, waste rubber powder (WRP) was devulcanized by ultrasonic in alkaline medium and blended with the different ratios of EPDM/PP and the coupling agent of dicumyl peroxide (DCP) to produce WRD/EPDM/PP polymer blends. With the concentration of 10 wt.% (by weight) WRP gived the mechanical properties of blends before and after accelerated weathering testing were approxiated with those of EPDM/PP 30/70 blends. The presence of DCP improved the tensile at strength and thermal resistance, caused by interaction beetwen EPDM and PP. The results of thermogravimetric analysis showed that the presence of 0.5 %DCP gaved the maximum thermal resistance of polymer blends up to 380°C.
Oleananesaponins from Gymnema sylvestre
Authors: Yen Duong Thi Hai , Van Toan Nguyen , Tai Bui Huu , Yen Pham Hai , Nhiem Nguyen Xuan , Van Kiem Phan 
Published: February 2020

AbstractBy using combined chromatographic methods, four oleananesaponins, namely, 3β‐O‐β‐D‐glucopyranosyl‐(1 → 6)‐β‐D‐glucopyranosyloleanolic acid 28‐O‐β‐D‐glucopyranosyl ester (1), gymnemoside‐W1 (2), 3β‐O‐β‐D‐xylopyranosyl‐(1 → 6)‐β‐D‐glucopyranosyl‐(1 → 6)‐β‐D‐glucopyranosyl oleanolic acid 28‐O‐β‐D‐glucopyranosyl ester (3), and alternoside XIX (4) were isolated from the methanol extract of the leaves of Gymnema sylvestre (Retz.) R.Br. ex Schult. Their structures were identified on the basis of spectroscopic evidence and in comparison with those reported in the literature.
Air disinfection and food preservation by ozone gas
Authors: Nghi Nguyen Hoang , Cuong Le Cao , Dieu Tran Vinh , Oanh Doan Thi Yen 
Published: February 2020

AbstractMost food spoilage is the result of bio‐chemical reactions between microorganisms such as bacteria, funguses, molds, yests and food as carbon based organic matters. Food preservation by ozone gas slows or prevents this biochemical reaction. Ozone consumed for these reactions causes its reduction or decomposition. The amylaceous food (bread and other) and some kinds of fruits were chosen for research. The shape of the ozone reduction curves, its rate and half life time (HLT) reflects the rate of reaction between ozone and microorganism on food. The bacteriobiological and photographic analysis of the samples before and after ozone treatment show that ozone gas can kill or prevent the growth of funguses and mould so this gas can be effectively used to preserve the food.
Evaluation of bioactive glass synthesized by alkali‐mediated sol‐gel process
Authors: Vuong Bui Xuan 
Published: February 2020

AbstractThe main objective of this research is the elaboration of bioactive glass 58S by an alkali‐mediated sol‐gel method. In which, the ammonia solution was used to transfer sol to gel state, and then the gel was dried by using the free‐drying technique. The dried gel was heated at 700°C in 2 h to convert into glass powder. The XRD analysis confirmed the amorphous and glassy properties of synthetic bioglass. The specific surface area of 99.146 m2/g of this bioglass was identified by using a low‐temperature nitrogen adsorption technique. In vitro experiments were performed by soaking the powder samples in the simulated body fluid (SBF) at several times. The XRD patterns and SEM images high lighted the bioactivity of bioglass by the formation of a dense and visible hydroxyapatite layer on the glass's surface after only 2 days of in vitro assays. ICP‐OES spectrometry was also used to illustrate the ion exchange behaviors between the bioactive glass 58S and the SBF solution.
Molecular iodine‐catalyzed N‐benzylation of anilines substituted by electron withdrawing groups
Authors: Tram Nguyen Thi Thu , Dat Tong Ho , Phong Truong Hoai , Dam Nguyen Phuc , Tuan Nguyen Trong 
Published: February 2020

AbstractFourteen derivatives of N‐alkylated anilines bearing electron withdrawing group from available aryl alcohols and the parent N‐unsubstituted aniline using iodine‐catalyst were synthesized throughout a convenient and green protocol, in which three derivatives were previously unreported compounds. The structures of these compounds were elucidated by HRMS, NMR spectral data and in comparison with the literature.
Prospects of application of melanins as antiaging agents in elastomer compositions
Authors: Kablov Victor F. , Novopoltseva Oksana M. , Gracheva Natalya V. , Zheltobryukho Victor F. , Dao Pham Kim 
Published: February 2020

AbstractThe paper presents findings of a study of physical‐chemical properties of sunflower husk melanins, as well as their influence on the thermal oxidative aging resistance of elastomer compositions. It has been found that melanins reveal a high level of antioxidant activity and can be used as antiaging agents in elastomer compositions.
Several combustion behaviours of the whistling pyrotechnic based on potassium perchlorate and sodium benzoate
Authors: Sang Dam Quang , Van Tinh Nguyen , Van Bo Nguyen 
Published: February 2020

AbstractThis study reported the influence of oxidizer‐fuel content and particle size of the fuel on combustion characteristics of the whistling mixture based on potassium perchlorate and sodium benzoate such as heat of explosion, the specific volume of gaseous products, burning rate and intensity of whistling sound. From the analysis of theoretical prediction and experimental data, we selected an appropriate ingredient and particle sizes of components in order to archive the optimal intensity of the whistle. The whistling pyrotechnic has a relatively low sensitivity to friction and could be safely used for several military and civilian applications.
Feasibility of goethite nanoparticles for Pb(II) and Cd(II) removal from aqueous solution
Authors: Vinh Nguyen Dinh , Thao Pham Thi Phuong , Hanh Nguyen Thi 
Published: February 2020

AbstractIn this study, goethite nanoparticles were successfully synthesized by chemical precipitation approach with the assistance of microwave aimed to adsorb heavy metals from water. The phase and morphology of the obtained sample was characterized using XRD and SEM methods. The feasibility of goethite nanoparticles for Pb(II) and Cd(II) removal from aqueous solution was evaluated. The effects of pH, contact time, and initial heavy metals concentrations were investigated. The adsorption of Pb(II) and Cd(II) on goethite remarkably depended on the pH of the solution and contact time. Adsorption kinetics for both metals obeyed the pseudo‐second‐order and the adsorption data fit well with the Langmuir adsorption model. The maximum adsorption of Pb(II) and Cd(II) on goethite nanoparticles was 111.11 and 76.92 mg.g‐1 at pH 5.5 after 120 and 90 min of the contact time, respectively.
Navigating collinear superspace
Authors: Cohen Timothy , Elor Gilly , Larkoski Andrew J. , Thaler Jesse 
Published: February 2020

AbstractWe introduce a new set of effective field theory rules for constructing Lagrangians with$$ \mathcal{N} $$N= 1 supersymmetry in collinear superspace. In the standard superspace treatment, superfields are functions of the coordinates$$ \left({x}^{\mu },{\theta}^{\alpha },{\theta}^{\dagger \overset{\cdot }{\alpha }}\right) $$xμθαθ†α⋅, and supersymmetry preservation is manifest at the Lagrangian level in part due to the inclusion of auxiliaryF- andD-term components. By contrast, collinear superspace depends on a smaller set of coordinates (xμ, η, η†), whereηis a complex Grassmann number without a spinor index. This provides a formulation of supersymmetric theories that depends exclusively on propagating degrees of freedom, at the expense of obscuring Lorentz invariance and introducing inverse momentum scales. After establishing the general framework, we construct collinear superspace Lagrangians for free chiral matter and non-Abelian gauge fields. For the latter construction, an important ingredient is a superfield representation that is simultaneously chiral, anti-chiral, and real; this novel object encodes residual gauge transformations on the light cone. Additionally, we discuss a fundamental obstruction to constructing inter- acting theories with chiral matter; overcoming these issues is the subject of our companion paper, where we introduce a larger set of superfields to realize the full range of interactions compatible with$$ \mathcal{N} $$N= 1. Along the way, we provide a novel framing of reparametrization invariance using a spinor decomposition, which provides insight into this important light-cone symmetry.
Leading singularities and classical gravitational scattering
Authors: Cachazo Freddy , Guevara Alfredo 
Published: February 2020

Abstract
In this work we propose to use leading singularities to obtain the classical pieces of amplitudes of two massive particles whose only interaction is gravitational. Leading singularities are generalizations of unitarity cuts. At one-loop we find that leading singularities obtained by multiple discontinuities in the t-channel contain all the classical information. As the main example, we show how to obtain a compact formula for the fully relativistic classical one-loop contribution to the scattering of two particles with different masses. The non-relativistic limit of the leading singularity agrees with known results in the post-Newtonian expansion. We also compute a variety of higher loop leading singularities including some all-loop families and study some of their properties.
Decomposition of graded local cohomology tables
Authors: De Stefani Alessandro , Smirnov Ilya 
Published: February 2020

AbstractLet R be a polynomial ring over a field. We describe the extremal rays and the facets of the cone of local cohomology tables of finitely generated graded R-modules of dimension at most two. Moreover, we show that any point inside the cone can be written as a finite linear combination, with positive rational coefficients, of points belonging to the extremal rays of the cone. We also provide algorithms to obtain decompositions in terms of extremal points and facets.
Differentiation of distal ureteral stones and pelvic phleboliths using a convolutional neural network
Authors: Jendeberg Johan , Thunberg Per , Lidén Mats 
Published: February 2020

AbstractThe objectives were to develop and validate a Convolutional Neural Network (CNN) using local features for differentiating distal ureteral stones from pelvic phleboliths, compare the CNN method with a semi-quantitative method and with radiologists’ assessments and to evaluate whether the assessment of a calcification and its local surroundings is sufficient for discriminating ureteral stones from pelvic phleboliths in non-contrast-enhanced CT (NECT). We retrospectively included 341 consecutive patients with acute renal colic and a ureteral stone on NECT showing either a distal ureteral stone, a phlebolith or both. A 2.5-dimensional CNN (2.5D-CNN) model was used, where perpendicular axial, coronal and sagittal images through each calcification were used as input data for the CNN. The CNN was trained on 384 calcifications, and evaluated on an unseen dataset of 50 stones and 50 phleboliths. The CNN was compared to the assessment by seven radiologists who reviewed a local 5 × 5 × 5 cm image stack surrounding each calcification, and to a semi-quantitative method using cut-off values based on the attenuation and volume of the calcifications. The CNN differentiated stones and phleboliths with a sensitivity, specificity and accuracy of 94%, 90% and 92% and an AUC of 0.95. This was similar to a majority vote accuracy of 93% and significantly higher (p = 0.03) than the mean radiologist accuracy of 86%. The semi-quantitative method accuracy was 49%. In conclusion, the CNN differentiated ureteral stones from phleboliths with higher accuracy than the mean of seven radiologists’ assessments using local features. However, more than local features are needed to reach optimal discrimination.