bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of laccol‐modified epoxy on fracture toughness of carbon fabric reinforced biobased epoxy composite
Authors: Trung Dang Huu , Dieu Tran Vinh , Oanh Doan Thi Yen , Hai Trinh Thi
Published: March 2024

Laccol is a main component of Vietnamese lacquer sap (Rhus succedanea), it is a natural phenol with two hydroxyl groups in octo‐position and unsaturated side chains. The laccol‐modified epoxy was directly dispersed in the epoxy resin and then the modified matrices were cured with cyanethyl‐diethylenetriamine (CEDETA) as a curing agent. The reaction of the epoxy epikote 828 with the laccol was studied using mid FT‐IR spectroscopic techniques. Effects of laccol contents in the epoxy matrix and carbon fabric/epoxy (CF/EP) composites on the izod impact strength and mode‐I interlaminar fracture toughness were investigated. The obtained testing results showed that the izod impact strength of epoxy matrix significantly increased by 35 % when 20 wt.% laccol was dispersed in the epoxy matrix. In addition, the mode‐I interlaminar fracture toughness of CF/EP composites at crack initiation (GIC) and propagation (GIP) were also improved by 59 % and 43 %, respectively, by using 20 wt.% laccol. Damaged surfaces of fractured samples were investigated using scanning electron microscopy (SEM) techniques. The overall results have shown that it is possible to obtain excellent impact strength and mode I interlaminar fracture toughness with the use of laccol as a toughness agent for the epoxy resins.
Diterpenoids from Rosmarinus officinalis L. and their nitric oxide inhibitory activity
Authors: Huyen Le Thi , Oanh Le Thi
Published: March 2024

One icetexane diterpenoid, demethylsalvicanol (1) and four abietane diterpenoids, sageone (2), 20‐deoxocarnosol (3), 11,12,20‐trihydroxy‐abieta‐8,11,13‐triene (4), and 7αα‐ethoxyrosmanol (5) were isolated from the n‐hexane layer of the leaves and twigs of Rosmarinus officinalis L. Chemical structures of compounds were identified by ESI‐MS, 1D‐, 2D‐NMR spectra and by comparison of the spectral data in the literature. Compounds 1‐5 were evaluated anti‐inflammatory activity by inhibitory NO production, LPS stimulated on RAW 264.7 cells. At a concentration of 100 μM, compound 4 exhibited inhibitory percentage of 34.7±1.8 %, meanwhile compounds 1‐3 and 5 showed cytotoxic effect. After dilution to concentration of 20 μM, except compound 1 and 2, compounds 3‐5 did not show cytotoxic effect. Their NO inhibitory productions were ranging from 20.5±2.4 % to 26.7±1.9 %. Compounds 1, 3 and 4 have been reported for the first time from the Rosmarinus genus.
Validation of the method for determination of Phenolphthalein and Sibutramine in weight‐loss functional foods from Viet Nam by UPLC‐MS/MS
Authors: Hieu Tran Quang , Vi Phan Pham Huynh , Phuong Pham Kim , Bien Lai Thi Kim , Tan Nguyen Thanh
Published: March 2024

A rapid, selective, and sensitive method by using ultra‐performance liquid chromatography‐tandem mass spectrometry (UPLC‐MS/MS) for the simultaneous determination of phenolphthalein (PP) and sibutramine (SB) in weight‐loss functional foods was developed. The optimal conditions of liquid chromatographic separation and mass spectroscopy of PP and SB have also been examined. The linear ranges for both PP and SB detected by the method were 0.20÷10.0 ng/mL, and corresponding correlation coefficients of 0.9991 and 0.9992, respectively. Mean recoveries of both analytes in the weight‐loss functional foods at three spike levels (low, medium, and high) were within the range of 98.5÷102.5 % (n = 11). LOD, LOQ values of PP were 0.12 and 0.36 ng/mL, respectively, while SB's LOD and LOQ were 0.09 ng/mL and 0.28 ng/mL. The impact of the matrix effect on the accuracy, repeatability, and recovery of the process was negligible. The recommended approach was applied to determine the content of the two substances in ten weight‐loss drug capsules and nine weight‐loss herbal teas, which were purchased in Ho Chi Minh City Viet Nam in 2019. PP was found in 5 of 19 samples, and SB was detected in 6 of 19 samples.
Antimicrobial and computational investigation of two 2,3‐dihydro‐1H‐inden‐1‐one derived fluorinated chalcone motifs
Authors: Shinde Rahul Ashok , Adole Vishnu Ashok , Jagdale Bapu Sonu
Published: March 2024

In this work, we report the anti‐microbial and computational study of two 2,3‐dihydro‐1H‐inden‐1‐one derived fluorinated chalcone scaffolds. The (E)‐2‐(4‐(trifluoromethyl)benzylidene)‐2,3‐dihydro‐1H‐inden‐1‐one (TFMBD‐1) and (E)‐2‐(4‐(trifluoromethoxy)benzylidene)‐2,3‐dihydro‐1H‐inden‐1‐one (TFMBD‐2) were synthesized by Claisen‐Schmidt reaction. The in‐depth structural analysis of optimized molecular structures, bond lengths and bond angles has been discussed by using density functional theory (DFT) with B3LYP/6‐311++G(d,p) basis set. The geometrical parameters, frontier molecular orbitals, global reactivity parameters, and MESP surfaces were all predicted using the same basis set on completely optimized geometries. Ionization potential, electron affinity, electronegativity, chemical hardness, global softness, global electrophilicity, and chemical potential were calculated using HOMO and LUMO energy values. Besides, the synthesized compounds were screened for their in‐vitro antibacterial and antifungal study. Antibacterial activity was screened against two Gram‐negative bacteria, E. coli and P. vulgaris, as well as against two Gram‐positive bacteria, S. aureus and B. subtilis, and antifungal activity was evaluated against A. niger and C. albicans. The TFMBD‐1 was revealed to be a more effective antibacterial and antifungal agent than TFMBD‐2.
Synthesis, spectral and thermal studies of new Schiff base copper(II) complexes with their biological effect on Entomopathogenic nematodes
Authors: El‐Boraey Hanaa A. , Abdel‐Rahman Randa M. , Atia Ensaf M. , EL‐Gammal Ohyla A.
Published: March 2024

New Schiff base ligands; (Z)‐1,5‐diphenyl‐2‐((thiophen‐2‐ylmethylene)amino)‐1H‐pyrrole‐3‐carbonitrile (L1); or (Z)‐2‐((2,4‐dihydroxybenzylidene)amino)‐1,5‐diphenyl‐1H‐pyrrole‐3‐carbonitrile (H2L2) and their Cu(II) complexes have been isolated and characterized using elemental analysis, spectral (FT‐IR, 1H NMR, UV/vis, EPR), molar conductivity and magnetic moment measurements, in addition to thermal techniques. FT‐IR spectra established that the Schiff base L1 coordinates as neutral bidentate or tridentate ligand. While the Schiff base H2L2 ligates as neutral or monobasic bidentate ligand. The EPR spectra indicated covalent nature of complexes [CuL1(OH)]Cl.2H2O (1), [CuL1(OH)(H2O)2]NO3.2H2O (2), [Cu(H2L2)Cl(H2O)3]Cl.H2O (5) and [Cu(HL2)NO3(H2O)3].H2O (6). The biological effect of Cu(II) ions, current ligands and complexes (1, 5) on the mortality and rate of reproduction of Entomopathogenic nematodes (Heterorhabditis bacteriophora and Steinernema carpocapsae) was studied. The results showed that, the obtained Schiff base ligands and their Cu(II) complexes make detoxification of the lethal effect of Cu(II) ions on the beneficial Entomopathogenic nematodes and complex (1) scored the highest reproduction potential.
Thermodynamic excess functions in organic ternary mixture ‐ Statistical approach (Cibulka expansion)
Authors: Sasikumar P. , Thiyagarajan R. , Mohammed M. K. A. , Nagaraj G. , Revathy M. S. , Palaniappan L. , Nithiyanantham S.
Published: March 2024

Acoustic velocity (U), viscosity (η), and density (ρ) characteristics were conducted for different ternary blends of aniline + toluene mixed with some 1‐alcohols at 303 K. Acoustical quantities such as adiabatic compressibility (β), free length (Lf), free volume (Vf), and internal pressure (πi) are acquired from the obtained results for all the blends, with a perspective to study the nature of molecular interaction. These parameters were analyzed along with their excess values (AE) and are found to be useful in evaluating the strength and magnitude of interaction in the blends. The measurement reveals that the interaction between the aniline‐alcohol complexes predominant the other interaction. The excess parameters are fitted to polynomial‐kind Cibulka formula and the coefficient of the fitting are found to be corroborate this work.
In silico screening for inhibitory potentiality towards protein structure tyrosine phosphatase 1B of sulfonylureas derivatives
Authors: Bui Thanh Q. , Thoi Bui Thi , Quy Phan Tu , Nguyen Nguyen Phuong Dai , Thao Tran Thi Phuong , Van Chien Tran , Van Loc Tran , Nhung Nguyen Thi Ai
Published: March 2024

Sulfonylureas derivatives were demonstrated to be effective inhibitors towards α‐glucosidase, thus also expected possessing inhibitory potentiality towards tyrosine phosphatase structure 1B. Five new sulfonylureas derivatives (S1‐S5), exhibiting α‐glucosidase inhibition activity, were selected for in silico screening for inhibitability towards UniProtKB‐PTP1B structure. Density functional theory confirms their existence; natural bond orbital analysis infers their stability; electronic transferability suggests their capability regarding intermolecular interaction. Docking‐based investigation interprets the inhibitory potentiality of the compounds into the order of complexes: S3‐PTP1B > S4‐PTP1B > S1‐PTP1B > S5‐PTP1B > S2‐PTP1B. QSARS‐based analysis specifies S4 as the most physicochemically and pharmaceutically compatible candidate for the general application as a protein inhibitor (Molecular mass: 213.9 amu; Dispersion coefficient: LogP 4.01; DSaverage: 11.9 kcal.mol‐1). The computer‐based findings encourage further confirmation from experiment‐based researches and development for a versatile inhibitor towards diabetes‐related protein structures (aka. α‐glucosidase and tyrosine phosphatase structure 1B).
Facile synthesis of hydroxyapatite from bovine bone and gelatin/chitosan‐hydroxyapatite scaffold for potential tissue engineering application
Authors: Anh Nguyen Thi Hong , Trinh Tra Phuong , Tan Le Van , Tho Nguyen Thi Mai , Van Cuong Nguyen
Published: March 2024

Here, hydroxyapatite was obtained from bovine bones by thermal decomposition at temperatures from 550 to 850°C at the time of 5 hours. The physical characterization showed that all organic components in the bovine bones were eliminated and produced the clean hydroxyapatite. Composite scaffolds were made of the gelatin (G), chitosan (C), and hydroxyapatite (HAp) in various gelatin/chitosan‐HAp mass ratios by the freeze‐drying method. The FT‐IR, SEM, XRD, and EDX techniques were used to examine the structures of synthetic HAp and composite scaffolds. XRD showed three main peaks at 2θ = 31.8, 33.1, and 40.1o, which resembled the characteristic peaks of hydroxyapatite and approved the formation of HAp at 850°C. FT‐IR results at 1360 and 1554 cm‐1 confirmed the formation of –C=N‐ bond of the interaction between chitosan and gelatin to form a 3D interconnected network in scaffolds. The swelling and in‐vitro degradation of composite scaffolds were carried out in PBS and 10 %FBS + PBS solutions. All composite scaffolds demonstrated the cell viability of L929 was above 95 %. These results indicated that the composite showed a potential application in tissue engineering.
Design and synthesis of two Strychnidin‐oxiran‐naphthalenol derivatives and their theoretical evaluation as noradrenaline and serotonin reuptake inhibitors
Authors: Lauro Figueroa‐Valverde , Francisco Díaz‐Cedillo , Ricardo Gobato , Heidari Alireza , Rosas‐Nexticapa  , Marcela  , Maria López‐Ramos , Virginia Mateu‐Armad Maria , Magdalena Alvarez‐Ramirez , Tomas Lopez‐Gutierrez
Published: March 2024

Several agents have been used as biogenic amine reuptake inhibitors for depression such as imipramine, fluoxetine, reboxetine, and others; however, some of these drugs can produce some secondary effects such as tiredness and psychomotor retardation. Analyzing these data, the aim of this study was to synthesize two Strychnidin‐oxiran‐naphthalenol derivatives using some chemical tools. Besides, the theoretical interaction of Strychnin‐oxiran‐naphthalenol derivatives (compounds 7 and 8) as noradrenaline and serotonin reuptake inhibitors was evaluated using two proteins (1ieo and 5i6z) as theoretical models in a docking model. The results showed a good yielding to synthesis of compounds 7 and 8. Other data suggest that either compounds 7 or 8 could interact with both 1ieo and 5i6z proteins surface, this phenomenon may be translated as changes in the biological activity of norepinephrine and serotonin reuptake. Therefore, compounds 7 and 8 could be considered two good candidates as antidepressants agents.
Nickel ferrite nanoparticles‐doped graphene oxide as a heterogeneous Fenton catalyst: Synthesis, characterization, and catalytic application
Authors: Thy Lu Thi Mong , Tuyen Nguyen Ngoc Kim , Viet Nguyen Duc , Huong Le Minh , Tinh Ninh Thi , Lin Tong Hoang , Son Nguyen Truong , Oanh Doan Thi Yen , Phong Mai Thanh , Hieu Nguyen Huu
Published: March 2024

In this study, nickel ferrite nanoparticles‐doped graphene oxide nanocomposite (NiFe2O4/GO or NG) was fabricated by impregnation method with five different mass ratios of NiFe2O4:GO, namely, 1:1, 3:7, 4:6, 7:3, and 6:4, corresponding to NG1, NG2, NG3, NG4, and NG5 samples. According to the catalytic efficiency of the Fenton reaction of methylene blue (MB), the NG3 sample was chosen as the most appropriate sample, which possessed the highest catalytic efficiency. The effects of volume of H2O2, reaction time, and MB concentration, on the catalytic efficiency of NG3, were also investigated. The results revealed that with the 0.5 mL H2O2, MB concentration of 150 mg/L, and 60 min, the NG3 sample exhibited the highest catalytic efficiency of more than 99 %. The characterization of NG3 was investigated by advanced analysis methods. The results indicated that NiFe2O4 possessed a sphere shape with the size of 10‐30 nm, which was uniformly distributed on the GO sheets. Additionally, NG3 possessed a high specific surface area and magnetism. The above results confirmed that NiFe2O4/GO can be potentially applied in the treatment of organic dyes in water.
Flavonoid from the aerial parts of Cardiospermum halicacabum L.
Authors: Linh Nguyen Thi Thuy , Cham Ba Thi , Anh Nguyen Thi Hoang , Quan Tran Duc , Nhung Le Thi Hong , Thang Le Quoc , Adorisio Sabrina , Delfino Domenico V , Thuy Trinh Thi
Published: March 2024

The first chemical investigation on Cardiospermum halicacabum L. growing in Vietnam led to the isolation and structural determination of nine flavonoid compounds, including quercetin 3‐O‐β‐D‐glucoside (1), quercetin 3‐O‐α‐L‐rhamnoside (2), quercetin (3), kaempferol 3‐O‐α‐L‐rhamnoside (4), kaempferol (5), apigenin 7‐O‐β‐D‐glucuronide butyl ester (6), apigenin 7‐O‐β‐D‐glucuronide methyl ester (7), apigenin (8), and luteolin (9). Their structures were established by using HR ESI MS, 1D and 2D NMR spectroscopic methods and comparison with those of the related published data. With exceptions to flavonoids 3 and 8, the rest seven compounds (1‐2, 4‐7, and 9) were found for the first time from this plant. Notably, two rare flavonoids (6 and 7) have not yet been reported from the Sapindaceae family before.
Chemical constituents of the roots of Vietnamese Panax pseudoginseng
Authors: Van Hung Hoang , Tan Luc Quang , Hoang Nguyen Huy , Tai Bui Huu , Van Kiem Phan
Published: March 2024

Panax pseudoginseng is very precious national medicinal plant in Vietnam. Phytochemical study on the methanol extract of the roots of this plant led to the isolation of ten dammarane‐type triterpene glycosides including (20S)‐sanchirhinoside (1), 6‐O‐(β‐D‐glucopyranosyl)‐20‐O‐(β‐D‐xylopyranosyl)‐3β,6α,12β,20(S)‐tetrahydroxydrammar‐24‐ene (2), chikusetsusaponin L5 (3), notoginsenoside R1 (4), ginsenoside Re (5), ginsenoside Rb1 (6), ginsenoside F2 (7), ginsenoside Rd (8), ginsenoside F1 (9), and ginsenoside Rg1 (10). Their structures identified by HR‐ESI‐MS, 1D and 2D NMR data in comparison with the reported data. All the isolates showed significant inhibitory effects on NO production in the LPS stimulated RAW 264.7 cells with the IC50 values ranging from 21.04±2.21 to 32.21±2.12 μM, compared to a value of 9.80±0.78 μM for the positive control compound, NG‐monomethyl‐L‐arginine (L‐NMMA). In addition, the HPLC‐DAD methods were developed for quantitative analysis of the P. pseudoginseng roots showed that compounds 4, 6, 8, and 10 are the main components with the corresponding content of 0.74, 3.02, 0.65, and 3.58 % of the dried sample. This developed HPLC‐DAD method provides an adequate linearity (R2 > 0.999). This validated method was also conducted to determine four main components of P. pseudoginseng roots.
Diketopiperazines from Rhabdastrella globostellata
Authors: Trang Do Thi , Dung Duong Thi , Hang Dan Thi Thuy , Dung Nguyen Viet , Linh Tran My , Mai Nguyen Chi , Yen Pham Hai , An Do Hoai , Nhiem Nguyen Xuan , Van Kiem Phan , Tai Bui Huu
Published: March 2024

From the methanol extract of the Vietnamese marine sponge Rhabdastrella globostellata (Carter, 1883), four diketopiperazines (1‐4) and one indol alkaloid (5) were isolated by various chromatographic methods. Their chemical structures were identified to be cyclo‐(L‐Pro‐L‐Ile) (1), cyclo‐(L‐Pro‐L‐Leu) (2), cyclo‐(D‐Pro‐L‐Ile) (3), cyclo‐(L‐Pro‐L‐Phe) (4), and tryptophol (5) by using a combination of ESI‐MS, 1D and 2D NMR spectral data as well as by comparison with previous literature. This is the first report of these compounds from Rhabdastrella globostellata.
MIL‐53(Fe)/rGO: A new material applied in an electrochemical sensor for detection of Cd(II) ions in aqueous solutions
Authors: Hue Dang Thi Minh , Luyen Tran Thi , Giang Hoang Thi Linh , Hoang Tran Vinh
Published: March 2024

A metal organic framework/reduced graphene oxide nanocomposite is fabricated using an effective two‐step protocol. X‐ray diffraction and scanning electron microscopy results demonstrate that the MIL‐53(Fe) is formed on the reduced graphene oxide's surface with an average particle size of 1.13 μm. A glassy carbon electrode modified with MIL‐53(Fe)/rGO is obtained by drop‐casting of the nanomaterial onto the GCE's surface, and this result is proven by electrochemical measurements. The glassy carbon electrode modified with MIL‐53(Fe)/rGO is used as an electrochemical sensor for detection of Cd2+ in aqueous solutions by a differential pulse voltammetry technique. The sensor shows outstanding merits including the ability of direct detection, a rapid detection time, and a quite high sensitivity. The relationship between the sensor's output signal and the concentration of Cd2+ ions is linear in the concentration range from 1.0 to 7.0 μM. The sensor has a detection limit of 698 nM.
Theoretical aspects of cooperativity and hydrogen bond in complexes of adenine and two formaldehyde molecules
Authors: Quyen Le Thi Tu , Nhu Vo Thi Kieu , Tri Nguyen Ngoc , Trung Nguyen Tien
Published: March 2024

In the present work, we use quantum chemical calculations to investigate the strength, origin and role of hydrogen bonds as well as their cooperativity in complexes of adenine with two formaldehyde molecules. Eight stable structures of complexes are determined on potential energy surface at the B3LYP/aug‐cc‐pVDZ level of theory. The interaction energies of complexes with ZPE and BSSE corrections range from ‐4.45 to ‐9.45 kcal.mol‐1. The NBO and AIM analyses indicate that the strength of complexes is mainly governed by the N‐H‧‧‧O hydrogen bonds predominating O=C‧‧‧O and C‐H‧‧‧O/N intermolecular interactions. Besides, the C‐H‧‧‧O/N contacts are blue shifting hydrogen bonds, while the red shift of N‐H stretching frequency occurs in N‐H‧‧‧O hydrogen bonds in the complexes investigated. Noticeably, it is found that the positive cooperativity makes an increase in the complex stability and the C‐H blue shift of stretching frequency in C‐H‧‧‧O hydrogen bonds upon complexation.
One‐pot synthesis of graphene oxide/poly(furfuryl alcohol) in deep eutectic solvent: A metal‐free electrocatalyst for non‐enzymatic glucose sensor application
Authors: Quynh Tran Ngan Thao , Phuong Cao Thanh , Khue Van Thanh , Hung Ngo Dai , Ngoc Dao Thi Bich , Tai Do Chiem , Thang Cao Xuan
Published: March 2024

A facile strategy is presented for the preparation of poly(furfuryl alcohol) functionalized graphene oxide (GO‐f‐PFA) by using Diels‐Alder (DA) click chemistry in deep eutectic solvent (DES), and its application in glucose sensing. The GO‐f‐PFA hybrid was obtained in a one‐pot procedure involving the polymerization reaction of furfuryl alcohol (FA) and subsequent DA reaction of poly(furfuryl alcohol) (PFA) with graphene oxide (GO). Both reactions were conducted in DES formed by the mixture of choline chloride: zinc chloride under assistance of ultrasonication without any catalyst. The highest percentage of grafted PFA in GO‐f‐PFA was 82.1 % at the DES/FA feeding weight ratio of 10. GO‐f‐PFA materials were analyzed by TGA, FTIR, XRD, Raman, SEM‐EDX and dispersion capacities were evaluated in various solvents such as water, ethanol, N,N’‐dimethylformamide, tetrahydrofuran, chloroform, and p‐xylene. GO‐f‐PFA was used as a free‐metal electrocatalytic material to fabricate the electrode for the recognition of glucose. The highest current density of GO‐f‐PFA was achieved to be 0.252 mA·cm‐2 using 10 mM glucose recorded at the potential of 0.7 V. These results have suggested the potential application of bio‐based materials for the fabrication of glucose biosensor.
Characteristics of organic titanate modified titanium dioxide nanoparticles and its dispersibility in acrylic emulsion coating
Authors: Chinh Nguyen Thuy , Mai Tran Thi , Hung Dao Phi , Hiep Nguyen Anh , Trang Nguyen Thi Thu , Trung Tran Huu , Thai Nguyen Xuan , Toan Dao Huu , Binh Dinh Thi My , Hoang Thai
Published: March 2024

This work presents the characteristics of rutile TiO2 nanoparticles modified by isopropyl tri[di(octyl) phosphato] titanate (KR‐12) with the content of 3, 5 and 10 wt.% as compared to TiO2 nanoparticles weight. The infrared (IR) spectroscopy, scanning electron microscopy (SEM), dynamic light scattering (DLS), and thermal gravimetry analysis (TGA) methods were used to evaluate the surface modification efficiency of the TiO2 nanoparticles with KR‐12. The TGA and IR analysis results indicated that the organic coupling agent (KR‐12) was grafted to the surface of the nanoparticles. The TiO2 nanoparticles after modification could disperse stably in water easily. The modification caused the shift of surface charge of the TiO2 nanoparticles to more positive region. The average particle size of TiO2 nanoparticles modified with 0, 3, 5, and 10 wt.% of KR‐12 was 443.9 nm, 295.3 nm, 334.8 nm, and 392.3 nm, respectively. The hydrophobic ability of TiO2 nanoparticles was improved significantly after modification. The modified TiO2 nanoparticles could well disperse in acrylic emulsion coating with dispersed phase size of 200‐400 nm.
Study on catalytic activity of Co(II) in Rhodamine B decolorization by peroxymonocarbonate in aqueous solution
Authors: Hanh Nguyen Thi , Huyen Pham Thi , Thu Nguyen Hoai , Ngan Nguyen Bich , Duy Vu Ngoc , Viet Nguyen Thi Bich
Published: March 2024

Decolorization of Rhodamine B (RhB) by peroxymonocarbonate (HCO4–) in aqueous solution was investigated in this study. All experiments were conducted in a 50 mL batch reactor at room temperature (26 ± 1°C) and pH of 9.0. The oxidizing agent (peroxymonocarbonate) was prepared in‐situ by the reaction between hydrogen peroxide and bicarbonate (molar ratio of H2O2:HCO3– is 2:1). The catalytic effect of four metal ions including Co(II), Cu(II), Fe(II), Mn(II) on the decolorization by HCO4– was evaluated. Co(II), the metal ion giving the best catalytic effect, has been selected to study the stability of peroxymonocarbonate agent. To clarify the role of H2O2 and HCO4– in oxidizing RhB dye, a series of experiments were conducted at different concentrations of HCO3‐ and Co(II) catalyst. UV and ultrasound irradiations were also tested for enhancing the decolorization rate. The results revealed that in the presence of Co(II) ion, HCO4– becomes more reactive and a synergic effect on the RhB degradation has been observed when both Co(II) and HCO4– are present in the oxidation system. And under UV light, complete decolorization of RhB by peroxymonocarbonate agent could be obtained after only 20 minutes of irradiation.
Synthesis, spectral characterization, DFT studies, and computational screening of 4‐amino‐3‐mercapto‐5‐methyl‐1,2,4‐triazole and its cadmium(II) mixed ligands complexes as potential antimalaria drug
Authors: Eno Ededet A. , Okon Emmanuel E. D. , Louis Hitler , Obot Nsikanabasi U. , Adalikwu Stephen A. , Unimuke Tomsmith O. , Gber Terkumbur E. , Chukwu Udochukwu G. , Ekoja Paulworship , Ogar Joseph , Owen Aniekan E. , Offiong Offiong E.
Published: March 2024

In this research paper we report the detailed synthesis, spectral (1H‐NMR, FT‐IR, and UV‐Vis), crystal structure determination, DFT studies, and molecular modeling of 4‐amino‐3‐mercapto‐5‐methyl‐1,2,4‐triazole (L2) Schiff base ligand and its complexes of cadmium as suitable bioactive agents for the treatment of malaria. From the spectroscopic results, the synthesized Schiff base has potentialtridentate coordination with themetal ion via hydroxy naphthalinic‐O, azomethine‐N and sulphur atom of the thione group. First principle theoretical calculations within the framework of density functional theory (DFT) were conducted to scrutinize the stability, reactivity, energetics, and the nature of bonding interactions in the studied Schiff base and its complexes. In‐silico molecular simulation was also executed to comprehend the conformation of interaction of the studied compounds against malaria (1LS5) protein for possible treatment of the disease. The observed binding affinity for the ligand (L2), its mono‐ligand complex [CdL2Cl], mixed ligands complex [CdL2TH]Cl and the standard drug are ‐7.23, ‐7.63, ‐7.3, and ‐7.60 kcal/mol, respectively, indicating that the Schiff base and is Cd2+ complexes have the potential to be developed into therapeutic drug for the treatment of malaria.
Detection of financial bubbles using a log‐periodic power law singularity (LPPLS) model
Authors: Shu Min , Song Ruiqiang
Published: March 2024

This article provides a systematic review of the theoretical and empirical academic literature on the development and extension of the log‐periodic power law singularity (LPPLS) model, which is also known as the Johansen–Ledoit–Sornette (JLS) model or log‐periodic power law (LPPL) model. Developed at the interface of financial economics, behavioral finance and statistical physics, the LPPLS model provides a flexible and quantitative framework for detecting financial bubbles and crashes by capturing two salient empirical characteristics of price trajectories in speculative bubble regimes: the faster‐than‐exponential growth of price leading to unsustainable growth ending with a finite crash‐time and the accelerating log‐periodic oscillations. We also demonstrate the LPPLS model by detecting the recent bubble status of the S&P 500 index between April 2020 and December 2022, during which the S&P 500 index reaches its all‐time peak at the end of 2021. We find that the strong corrections of the S&P 500 index starting from January 2022 stem from the increasingly systemic instability of the stock market itself, while the well‐known external shocks, such as the decades‐high inflation, aggressive monetary policy tightening by the Federal Reserve, and the impact of the Russia/Ukraine war, may serve as sparks.

This article is categorized under:

Applications of Computational Statistics > Computational Finance

Algorithms and Computational Methods > Computational Complexity

Statistical Models > Nonlinear Models
Global Finite-Energy Solutions of the Compressible Euler–Poisson Equations for General Pressure Laws with Large Initial Data of Spherical Symmetry
Authors: Chen Gui-Qiang G. , Huang Feimin , Li Tianhong , Wang Weiqiang , Wang Yong
Published: March 2024

We are concerned with global finite-energy solutions of the three-dimensional compressible Euler–Poisson equations with gravitational potential and general pressure law, especially including the constitutive equation of white dwarf stars. In this paper, we construct global finite-energy solutions of the Cauchy problem for the Euler–Poisson equations with large initial data of spherical symmetry as the inviscid limit of the solutions of the corresponding Cauchy problem for the compressible Navier–Stokes–Poisson equations. The strong convergence of the vanishing viscosity solutions is achieved through entropy analysis, uniform estimates in $$L^p$$

L
p

, and a more general compensated compactness framework via several new ingredients. A key estimate is first established for the integrability of the density over unbounded domains independent of the vanishing viscosity coefficient. Then a special entropy pair is carefully designed via solving a Goursat problem for the entropy equation such that a higher integrability of the velocity is established, which is a crucial step. Moreover, the weak entropy kernel for the general pressure law and its fractional derivatives of the required order near vacuum ($$\rho =0$$

ρ
=
0

) and far-field ($$\rho =\infty $$

ρ
=
∞

) are carefully analyzed. Owing to the generality of the pressure law, only the $$W^{-1,p}_{\textrm{loc}}$$

W
loc

-
1
,
p

-compactness of weak entropy dissipation measures with $$p\in [1,2)$$

p
∈
[
1
,
2
)

can be obtained; this is rescued by the equi-integrability of weak entropy pairs which can be established by the estimates obtained above, so that the div-curl lemma still applies. Finally, based on the above analysis of weak entropy pairs, the $$L^p$$

L
p

compensated compactness framework for the compressible Euler equations with general pressure law is established. This new compensated compactness framework and the techniques developed in this paper should be useful for solving further nonlinear problems with similar features.
Encoding contact size using static and dynamic electrotactile finger stimulation: natural decoding vs. trained cues
Authors: Henrich Mauricio Carlos , Garenfeld Martin A. , Malesevic Jovana , Strbac Matija , Dosen Strahinja
Published: March 2024

Electrotactile stimulation through matrix electrodes is a promising technology to restore high-resolution tactile feedback in extended reality applications. One of the fundamental tactile effects that should be simulated is the change in the size of the contact between the finger and a virtual object. The present study investigated how participants perceive the increase of stimulation area when stimulating the index finger using static or dynamic (moving) stimuli produced by activating 1 to 6 electrode pads. To assess the ability to interpret the stimulation from the natural cues (natural decoding), without any prior training, the participants were instructed to draw the size of the stimulated area and identify the size difference when comparing two consecutive stimulations. To investigate if other “non-natural” cues can improve the size estimation, the participants were asked to enumerate the number of active pads following a training protocol. The results demonstrated that participants could perceive the change in size without prior training (e.g., the estimated area correlated with the stimulated area, p < 0.001; ≥ two-pad difference recognized with > 80% success rate). However, natural decoding was also challenging, as the response area changed gradually and sometimes in complex patterns when increasing the number of active pads (e.g., four extra pads needed for the statistically significant difference). Nevertheless, by training the participants to utilize additional cues the limitations of natural perception could be compensated. After the training, the mismatch in the activated and estimated number of pads was less than one pad regardless of the stimulus size. Finally, introducing the movement of the stimulus substantially improved discrimination (e.g., 100% median success rate to recognize ≥ one-pad difference). The present study, therefore, provides insights into stimulation size perception, and practical guidelines on how to modulate pad activation to change the perceived size in static and dynamic scenarios.
Spotlight on the real-world treatment of CML pts in Germany: a retrospective survey in private oncology practices
Authors: Franke Georg-Nikolaus , Loewe Gunnar , Reiser Marcel , Linde Hartmut , Josting Andreas , von der Heyde Eyck , Platzbecker Uwe , Weide Rudolf , Tesch Hans , Nusch Arndt , Dengler Jolanta , Jentsch-Ullrich Kathleen
Published: March 2024

Clinical trials in chronic myeloid leukemia (CML) are usually carried out in specialized centers whereas primary care for patients (pts) with CML is mainly provided by local oncology practices. The aim of this study was to assess treatment practices in pts with CML in the setting of private oncology practices in Germany. We collected data of 819 pts with a confirmed diagnosis (dx) of CML in 2013 or later from 43 practices. At dx, 84.2% (n=690) and 9.4% (n=77) of pts were in chronic or accelerated phase, 0.7% (n=6) had a blast crisis. Molecular monitoring was provided by EUTOS certified laboratories in 87.7% of pts. Typical BCR::ABL1 transcripts were detected in 86.6% (n=709). Molecular response was assessed after 2.8, 6.0, 9.4 and 12.9 m (mean) after start of treatment. Of the pts with available data, 11.1% did not achieve early molecular response and at 18 m, 83.7% had at least a major molecular response. 288 (35.2%) of pts switched to 2nd line (2L) treatment after a mean of 21.0 months. Reasons for 2L treatment were side effects in 43.4% and suboptimal response or failure in 31.4% of pts. 106 pts went on to third line (3L) treatment. 36.8 % of pts switched to and 92.8 % of pts still on 3L treatment achieved BCR::ABL1IS ≤1% at 12 m. In conclusion, in Germany pts with CML are routinely monitored by qPCR and good responses are achieved in the majority. Treatment changes are mainly due to adverse events rather than suboptimal responses.
(Re)packing Equal Disks into Rectangle
Authors: Fomin Fedor V. , Golovach Petr A. , Inamdar Tanmay , Saurabh Saket , Zehavi Meirav
Published: March 2024

The problem of packing of equal disks (or circles) into a rectangle is a fundamental geometric problem. (By a packing here we mean an arrangement of disks in a rectangle without overlapping.) We consider the following algorithmic generalization of the equal disk packing problem. In this problem, for a given packing of equal disks into a rectangle, the question is whether by changing positions of a small number of disks, we can allocate space for packing more disks. More formally, in the repacking problem, for a given set of n equal disks packed into a rectangle and integers k and h, we ask whether it is possible by changing positions of at most h disks to pack $$n+k$$

n
+
k

disks. Thus the problem of packing equal disks is the special case of our problem with $$n=h=0$$

n
=
h
=
0

. While the computational complexity of packing equal disks into a rectangle remains open, we prove that the repacking problem is NP-hard already for $$h=0$$

h
=
0

. Our main algorithmic contribution is an algorithm that solves the repacking problem in time $$(h+k)^{\mathcal {O}(h+k)}\cdot |I|^{\mathcal {O}(1)}$$

(
h
+
k
)

O
(
h
+
k
)

·

|
I
|

O
(
1
)

, where |I| is the input size. That is, the problem is fixed-parameter tractable parameterized by k and h.
Altered conformational dynamics contribute to species-specific effects of cytochrome c mutations on caspase activation
Authors: Chin Thomas C. , Wilbanks Sigurd M. , Ledgerwood Elizabeth C.
Published: March 2024

Variants in the gene encoding human cytochrome c (CYCS) cause mild autosomal dominant thrombocytopenia. Despite high sequence conservation between mouse and human cytochrome c, this phenotype is not recapitulated in mice for the sole mutant (G41S) that has been investigated. The effect of the G41S mutation on the in vitro activities of cytochrome c is also not conserved between human and mouse. Peroxidase activity is increased in both mouse and human G41S variants, whereas apoptosome activation is increased for human G41S cytochrome c but decreased for mouse G41S cytochrome c. These apoptotic activities of cytochrome c are regulated at least in part by conformational dynamics of the main chain. Here we use computational and in vitro approaches to understand why the impact of the G41S mutation differs between mouse and human cytochromes c. The G41S mutation increases the inherent entropy and main chain mobility of human but not mouse cytochrome c. Exclusively in human G41S cytochrome c this is accompanied by a decrease in occupancy of H-bonds between protein and heme during simulations. These data demonstrate that binding of cytochrome c to Apaf-1 to trigger apoptosome formation, but not the peroxidase activity of cytochrome c, is enhanced by increased mobility of the native protein conformation.
Incorporating changeability for value-robust product-service systems: an integrative review
Authors: Machchhar Raj J. , Bertoni Alessandro , Wall Johan , Larsson Tobias
Published: March 2024

The ongoing servitization journey of the manufacturing industries instills a through-life perspective of value, where a combination of products and services is delivered to meet expectations. Often described as a product-service system (PSS), these systems are poised with many complexity aspects, introducing uncertainties during the design phase. Incorporating changeability is one of the known strategies to deal with such uncertainties, where the system changes in the face of uncertainty to sustain value, thereby achieving value robustness. While the theme of dealing with multiple uncertainties has been discussed since the inception of PSS, changeability is still poorly addressed. To bridge this gap, an integrative literature review is performed to outline various complexities aspects and their link to uncertainty from a PSS perspective. Also, the state-of-the-art approach to achieving value robustness is presented via changeability incorporation. Subsequently, a reference framework is proposed to guide decision-makers in changeability incorporation in PSS, especially during the early design stages.
On the development and analysis of coupled surface–subsurface models of catchments. Part 3. Analytical solutions and scaling laws
Authors: Morawiecki Piotr , Trinh Philippe H.
Published: March 2024

The objective of this three-part work is to formulate and rigorously analyse a number of reduced mathematical models that are nevertheless capable of describing the hydrology at the scale of a river basin (i.e. catchment). Coupled surface and subsurface flows are considered. In this third part, we focus on the development of analytical solutions and scaling laws for a benchmark catchment model that models the river flow (runoff) generated during a single rainfall. We demonstrate that for catchments characterised by a shallow impenetrable bedrock, the shallow-water approximation allows a reduction of the governing formulation to a coupled system of one-dimensional time-dependent equations for the surface and subsurface flows. Asymptotic analysis is used to derive semi-analytical solutions for the model. We provide simple asymptotic scaling laws describing the peak flow formation, and demonstrate its accuracy through a comparison with the two-dimensional model developed in Part 2. These scaling laws can be used as an analytical benchmark for assessing the validity of other physical, conceptual or statistical models of catchments.
Unraveling Island Economies through Organic Residue Analysis: The Case of Mocha Island (Southern Chile)
Authors: Montalvo-Cabrera Javier A. , Colonese André C. , Campbell Roberto , Talbot Helen M. , Lucquin Alexandre , Admiraal Marjolein , Palma Gabriela , Craig Oliver E.
Published: March 2024

Biophysical conditions played a fundamental role in early human colonization of insular territories, particularly in food-producing societies dealing with limited resources and the challenges of maintaining a sustainable carrying capacity. Studies on past human colonization of small oceanic islands thus offer insights into economic plasticity, ecological impacts, and adaptation of early food-producing groups. On the coast of southern Chile, early evidence is dated to 950 cal BP of island colonization by coastal populations with mainland subsistence systems based on the exploitation of marine resources, along with gathering, managing, and cultivating plants and hunting terrestrial animals. Strikingly, the extent to which these mixed economies contributed to insular colonization efforts is largely unknown. Here we used organic residue analysis of ceramic artifacts to shed light on the subsistence of populations on Mocha Island in southern Chile. We extracted and analyzed lipids from 51 pottery sherds associated with the El Vergel cultural complex that flourished in southern Chile between 950 and 400 cal BP. Chemical and stable isotope analysis of the extracts identified a range of food products, including C3 and C4 plants and marine organisms. The results reveal the central role of mixed subsistence systems in fueling the colonization of Mocha Island.
Baiting not-owned dogs against Echinococcus granulosus: innovative tools for integrated control
Authors: Ciccone Elena , Bosco Antonio , Pepe Paola , Nocerino Martina , Lattero Nicola , Umhang Gerald , AbdElkarim Laatamna , Lahmar Samia , Said Yousra , Saralli Giorgio , Piegari Giuseppe , Alterisio Maria Chiara , Baka Rania , Sotiraki Smaragda , Boué Franck , Rinaldi Laura
Published: March 2024

Cystic echinococcosis (CE), caused by the larval stage of the cestode Echinococcus granulosus, is one of the most widespread zoonoses in Mediterranean countries. Baiting not-owned dogs with praziquantel (PZQ), due to their key role in the maintaining the transmission of CE, currently appears to be the most effective way to limit the transmission of CE, as well as an important aspect to introduce for the control of this parasitic disease. Therefore, this study aims to test 3 types of PZQ-based baits by evaluating different parameters (integrity over time, attractiveness and palatability for dogs, and mechanical resistance after release to different altitudes) and the bait acceptance in field by target animals, i.e. not-owned dogs, by using camera traps. The double PZQ-laced baits (with a double layer of highly palatable chews) showed the greatest resistance in the environment while also preserving the attractiveness and palatability up to 10 days, also withstood heights of 25 m, thus resulting as the most suitable also for drone delivery. The results on the field showed that most of the baits were consumed by not-owned dogs (82.2%), while the remaining were consumed by wild boars (8.9%), foxes (6.7%), badgers (1.1%) and hedgehogs (1.1%), confirming the specific and high attractiveness of the double PZQ-laced baits for the target population and highlights how an anthelmintic baiting programme may be a viable tool for the management of E. granulosus among free-ranging dog populations in endemic rural areas.
Dimension in team semantics
Authors: Hella Lauri , Luosto Kerkko , Väänänen Jouko
Published: March 2024

We introduce three measures of complexity for families of sets. Each of the three measures, which we call dimensions, is defined in terms of the minimal number of convex subfamilies that are needed for covering the given family. For upper dimension, the subfamilies are required to contain a unique maximal set, for dual upper dimension a unique minimal set, and for cylindrical dimension both a unique maximal and a unique minimal set. In addition to considering dimensions of particular families of sets, we study the behavior of dimensions under operators that map families of sets to new families of sets. We identify natural sufficient criteria for such operators to preserve the growth class of the dimensions. We apply the theory of our dimensions for proving new hierarchy results for logics with team semantics. To this end we associate each atom with a natural notion or arity. First, we show that the standard logical operators preserve the growth classes of the families arising from the semantics of formulas in such logics. Second, we show that the upper dimension of
$k+1$
-ary dependence, inclusion, independence, anonymity, and exclusion atoms is in a strictly higher growth class than that of any k-ary atoms, whence the
$k+1$
-ary atoms are not definable in terms of any atoms of smaller arity.
Multi‐Spacecraft Magnetic Field Reconstructions: A Cross‐Scale Comparison of Methods
Authors: Broeren T. , Klein K. G. , TenBarge J. M.
Published: March 2024

Space plasma studies frequently use in situ magnetic field measurements taken from many spacecraft simultaneously. A useful data product of these measurements is the reconstructed magnetic field in a volume near the spacecraft observatory. We compare a standard Linear method of computing the magnetic field at arbitrary spatial points to two novel approaches: a Radial Basis Function interpolation and a time‐dependent 2D inverse distance weighted interpolation scheme called Timesync. These three methods, which only require in situ measurements of the magnetic fields and bulk plasma velocities at a sparse set of spatial points, are implemented on synthetic data drawn from a time‐evolving numerical simulation of plasma turbulence. We compare both the topology of the reconstructed field to the ground truth of the simulation and the statistics of the fluctuations found in the reconstructed field to those from the simulated turbulence. We conclude that the Radial Basis Function and Timesync methods outperform the Linear method in both topological and statistical comparisons.
Vertical Velocity Diagnosed From Surface Data With Machine Learning
Authors: He Jing , Mahadevan Amala
Published: March 2024

Submesoscale vertical velocities, w, are important for the oceanic transport of heat and biogeochemical properties, but observing w is challenging. New remote sensing technologies of horizontal surface velocity at O(1) km resolution can resolve surface submesoscale dynamics and offer promise for diagnosing w subsurface. Using machine learning models, we examine relationships between the three‐dimensional w field and remotely observable surface variables such as horizontal velocity, density, and their horizontal gradients. We evaluate the machine learning models' sensitivities to different inputs, spatial resolution of surface fields, the addition of noise, and information about the subsurface density. We find that surface data is sufficient for reconstructing w, and having high resolution horizontal velocities with minimal errors is crucial for accurate w predictions. This highlights the importance of finer scale surface velocity measurements and suggests that data‐driven methods may be effective tools for linking surface observations with vertical velocity and transport subsurface.
Magnetotail Variability During Magnetospheric Substorms
Authors: Kumar S. , Pulkkinen T. I. , Gjerloev J.
Published: March 2024

In this work, we present a statistical study of substorms covering a five‐year period 2016–2020. Substorm phases were identified from time series of the SuperMAG AL (SML) index using a list of 5,077 previously identified substorm onsets, the SML peak value marking transition from expansion to recovery phase, and the recovery identified as return to activity less than −100 nT in the SML index. Magnetic field observations from THEMIS, RBSP, and MMS missions were used to study the magnetotail characteristics during the substorm evolution. A superposed epoch analysis indicates that the substorm onset occurs almost simultaneously with a few minutes of uncertainty throughout the magnetotail, ranging from geostationary orbit to 20 RE. The onset in the transition region precedes the ground onset by a few minutes. The peak SML time coincides with the peak of the outer transition region ΔBZ, which suggests that the field‐aligned currents driving the SML activity arise from the outer transition region. Analysis of 2D maps of the tail magnetic field shows that the magnetotail current changes are limited to the center of the tail within |Y| < 10RE. The substorm recovery is fastest in the inner transition region and lasts longer when moving further out. We did not find major asymmetries in the substorm signatures associated with IMF BY or BZ.