bluuebunny/crossref_metadata_2025_split huggingface dataset:
An efficient synthesis of acridine‐aza‐anthraquinone hybrid compounds under microwave irradiation
Authors: Anh Dang Thi Tuyet , Giang Le Nhat Thuy , Van Tuyen Nguyen , Giang Nguyen Thi Quynh , Thanh Nguyen Ha 
Published: March 2024

AbstractThe efficient synthesis of 12‐substituted‐3,4,4a,5,12,12a‐hexahydrobenzo[b]acridine‐1,6,11(2H)‐triones starting from 2‐amino‐1,4‐naphthoquinone, 1,3‐cyclohexanedione, and different (hetero)aromatic aldehydes was developed. These reactions were carried out in acetic acid under microwave irradiation in the presence of p‐toluenesulfonic acid as catalyst. The structure of the newly synthesized compounds were confirmed employing spectroscopic data as well as elemental analysis. The plausible mechanism of these three‐component domino reactions was also described.
Secondary metabolites from leaves of Knema pachycarpa possessing cytotoxic and acetylcholinesterase inhibitory activities
Authors: Thanh Le Nguyen , Giap Tran Huu , Oanh Vu Thi Kim , Hue Vu Thi , Phuong Diep Thi Lan , Thuc Dinh Ngoc , Cong Nguyen Thanh , Vuong Nguyen Quoc 
Published: March 2024

AbstractPhytochemical study of Knema pachycarpa leaves led to the isolation of ten compounds. Their chemical structures were determined as (7”R, 8”R)‐hydnocarpin D (1), (7”R, 8”R)‐hydnocarpin (2), sinaicitin (3), (‐)‐globulol (4), β‐caryolanol (5), phytol (6), biochanin A (7), chrysoeriol (8), tanoside II (9) and astragalin (10) using NMR and MS spectral data. Among the isolates, (7”R, 8”R)‐hydnocarpin (2) showed good cytotoxic activity against KB, HepG‐2, Lu and MCF‐7 cancer cell lines with IC50 values from 13.99±0.62 μg/mL to 30.65±1.44 μg/mL. Compound 4 showed selective cytotoxicity against LU cancer cell line and significant acetylcholinesterase (AChE) inhibition with IC50 values of 12.31±0.51 μg/mL and 5.12±0.22 μg/mL, respectively.
Synthesis of yellow and green phosphors based on zinc orthosilicate doped by manganese at low temperature by impregnation – coprecipitation method
Authors: Thanh Nguyen Thi , Thanh Le Xuan 
Published: March 2024

AbstractThis work studies the influence of magnesium concentration, sintering temperature, boric and acetic acid to synthesize yellow and green phosphors based on zinc orthosilicate doped by manganese at low temperature by a novel approach, the impregnation ‐ coprecipitation method. The samples were investigated by thermal analysis, luminescence spectroscopy, XRD, SEM and EDS. The results showed that the single‐phase zinc magnesium orthosilicate/borosilicate phosphors doped by manganese with rhombo. H. axes structure of α‐Zn2SiO4 were successfully synthesized when sintering corresponding precursors at 900°C for 45 minutes. Their luminescence efficiency is higher than that of the control samples prepared by coprecipitation method. The magnesium content for the maximum luminescence efficiency is 20 mol % per mol of metal ions. The highest luminescence product consists of spheroidal and relatively uniform particles with sizes around 0.6‐1.0 μm. The variation of the precipitated precursor with temperature, the influence of sintering temperature on structure and luminescence, the mineralization role of boric acid and the chemical reactions that occur with generation of precipitated precursors and upon heating to give luminescent solid solution products are mentioned.
HO● ‐ initiated oxidation of isoleucine amino acid in the aqueous phase
Authors: Lan Nguyen Thi Huong , Hieu Truong Dinh , Chinh Ngo Thi , Le Anh Nguyen Thi , Nhi Pham Thi Yen , Quang Dao Duy 
Published: March 2024

AbstractProtein damage by the direct oxidative attack on amino acid side chains is considered the main cause of human aging and diseases. Therefore, a better understanding of the oxidation process is necessary for screening and designing new drugs. In this work, the oxidation of L‐isoleucine (Ile) by HO● radical was mechanistically and kinetically studied using M05‐2X/6‐311++G(3df,3pd)//M05‐2X/6‐311++G(d,p) level of theory. All possible hydrogen transfer (HT) and single electron transfer (SET) reactions are considered in the aqueous phase. The results showed that the overall diffusion‐controlled rate constant is equal to 4.82×109 M‐1s‐1 at 298.15K. The zwitterionic form is the main existing form that plays an essential role in the HO● ‐ initiated oxidation of Ile (99.98%). The most preponderant reactions are found at C6‐H (36.19%) and C8‐H (37.77%) positions. Finally, the influence of temperature on the overall rate is also evaluated.
Improving corrosion resistance of pure titanium by simple and controlled oxidation for biomedical applications
Authors: Linh Nguyen Thi Truc , Tung Mai Thanh , Tuan Phan Dinh 
Published: March 2024

AbstractIn this study, the TiO2 passive layer was formed on a pure titanium substrate by simple oxidation in an aqueous solution of H2O2 35 wt.%. In order to determine the appropriate time for the oxidation of the pure titanium substrate, the corrosion rate of the metal in the solution of H2O2 was investigated. The electrochemical behaviour of the TiO2 passive layer on the Ti substrate was investigated in Hank's solution at 37.5°C. The results show that Tafel‐plot extrapolations from the potentiodynamic curves revealed a substantial improvement in the corrosion potentials for the TiO2 coatings. According to the theory calculation, to obtain the optimal surface roughness values, around 100 nm to 300 nm, the oxidation time in H2O2 35 wt.% solution is controlled in the range of 2‐5 hours. The results were explained by considering the effects of crystal morphology and roughness. The results indicated that the controlled oxidation‐prepared TiO2 coatings have attractive prospects for use in biomedical applications since better corrosion protection of pure Ti can be expected.
Effect of silane‐modified SiO2@Ce3+ nanoparticles on the mechanical property and anti‐corrosion for steel of the epoxy coating
Authors: Huu Nguyen The , Tam Dam Thi , Vy Do Truc , Anh Nguyen Tuan , Lu Le Trong , Lam Tran Dai , Vuong Nguyen Thien 
Published: March 2024

AbstractIn this work, nano‐SiO2 have been used as nanocarriers for loading Ce(III) ions (SiO2@Ce3+). After loading, silane coupling agent has been used to modify these nanocarriers (m‐SiO2@Ce3+). Then, these modified nanocarriers were added as green inhibitors into the inner epoxy coating matrix, which was based on the epoxy resin (DER 671X75) and hardener (polyamide Epicure 3125). Morphological study by FE‐SEM showed that the spherical nanoparticles (m‐SiO2@Ce3+) were in size < 100 nm and dispersed rather homogeneously into the polyme matrix. In addition, the addition of nanocarriers at a concentration of 2.5 wt.% into the epoxy polymer matrix enhanced significantly its mechanical property. Besides, the anticorrosion performance of the epoxy polymer matrix due to the presence of m‐SiO2@Ce3+ (at 2.5 wt. %) was proved by EIS analysis and salt spray tests.
Matrix removal and enrichment of cadmium atnd lead in mineral‐rich samples using liquid‐liquid extraction and analysis by flame atomic absorption spectrometry
Authors: Thien Vo Hoang , Van Dong Nguyen 
Published: March 2024

AbstractThe present work aimed to study matrix removal and enrichment of cadmium and lead in samples containing highly mineral‐rich using liquid‐liquid extraction. Cadmium and lead were extracted by sodium diethyldithiocarbamate (DDTC) and ammonium pyrrolidine dithiocarbamate (APDC) in pH 5.0 buffer solution (acetic acid/acetate) to chloroform. Cd and Pb in chloroform were re‐extracted to the aqueous phase by 1.5 M HNO3 and subsequently determined by flame atomic absorption spectrometry (F–AAS). Mineral‐rich samples (soil, sediment, sea salt, etc.) containing various concentrations of interferent elements (Fe (8‐25%), Al (5‐20%), Cu (400‐500 ppm), Zn (300‐400 ppm), NaCl (up to ⁓100%)) were used to determine the effectiveness of matrix removal. Fe was found to form an undissolved complex with APDC and co‐extracted with Cd and Pb, deteriorating the extraction and following analysis manipulation. 8‐hydroxyquinoline was successfully used as a masking reagent to reduce the co‐extraction of Fe, Al, and other elements with Cd and Pb in the form of dithiocarbamate complexes. In this study, enrichment factors of 5 – 10 could be achieved (from 50 to 5 mL). The recoveries of Cd2+ and Pb2+ ions from spiked agricultural soil, tea–planted soil, basalt soil, forestry soil, livestock feed, and sea salt were 97‐101 % and 87‐92% for DDTC and APDC reagents, respectively. The detection limits of cadmium and lead in soil are 0.0069 and 0.072 μgg−1; in livestock feed, 0.0085 and 0.082 μgg−1; in sea salt, 0.0075 and 0.076 μgg−1, respectively The quantification limit of cadmium and lead in a soil sample is 0.023 and 0.24 μgg−1; in livestock feed of 0.028 and 0.27 μgg−1; and in sea salt of 0.025 and 0.25 mgKg−1, respectively. The proposed approach for matrix removal and pre‐concentration of cadmium and lead can also be applied for mineral‐rich samples with better analytical performances when higher sensitivity and multi‐element detection techniques such as inductively coupled plasma optical emission spectrometry or inductively coupled plasma mass spectrometry are used.
Studying the influence of current density and solution pH on corrosion properties of obtained Zn‐nano SiO2 electroplating layers
Authors: Huong Nguyen Thi Thanh , Thang Le Ba , Bao Le Duc , Hieu Truong Minh , Nam Truong Thi , Giang Pham Thi Thu , Van Vy Uong 
Published: March 2024

AbstractThe influence of fabrication conditions on the corrosion properties of obtaining Zn‐SiO2 plating was studied by electrochemical measurement methods and salt spray acceleration test. In which the current density is changed from 1.5 to 3.5 A/dm2 and the solution pH is adjusted from 4.5 to 6.2. The obtained results show that the coating with the best corrosion resistance is obtained when applying the following manufacturing conditions: current density of 2 A/dm2, solution pH of 5.2‐5.4 at room temperature, stirring speed of 14 cycles/min.
Synthesis and antimicrobial activity of new glucosamine derivatives
Authors: Anh Le Duc , Bao Ninh Duc , Duc Le Viet , Van Chinh Luu , Cuong Nguyen Manh , Thuy Dinh Thi Thu , Hung Truong Ngoc 
Published: March 2024

AbstractIn this study, a series of reactions were used to protect and deprotect hydroxyl and amine groups of D‐glucosamine which was obtained by the hydrolysis of chitin in concentrated HCl. Amidation of this protected monomer with aromatic and heteroaromatic acids was carried out in dichloromethane in the presence of DCC as a coupling reagent to produce new amides in good yields. Their structures were determined by NMR and MS spectra while their antifungal and antibacterial activities were screened.
Determination of saturated fat, unsaturated fat, and trans fat in commercial instant noodles based on the analysis of fatty acid composition by gas chromatography
Authors: Hung Nguyen Khanh , Trang Nguyen Phuong , Du Nguyen Huy 
Published: March 2024

AbstractIn the food processing sector, it is crucial to identify the composition and fat content of items that have undergone heat‐processing. The total fat content is the primary factor used to determine the fat content of instant noodle products. As a result, a technique must be developed to identify fat content by determination of fatty acid composition, particularly trans fatty acids. In this study, we used the reliable GC‐FID/MS technique to analyze the methyl ester derivatives of 37 different kinds of fatty acids. The results showed that high saturated fat concentration in all samples was mostly palmitic acid, whereas the low unsaturated fatty acid content in the cis form was primarily oleic acid and linoleic acid. The amount of monounsaturated and polyunsaturated fats is quite low. Trans fat level was almost non‐existent in all samples. The amounts of palmitic acid and oleic acid in the samples ranged from 4.10% to 12.84% and 2.62% to 7.65%, respectively, as did linoleic acid and stearic acid. Monounsaturated and polyunsaturated fatty acid concentration ranged from 2.62% to 7.82% and 0.52 to 1.81%, respectively. The proportion of polyunsaturated fat to saturated fat was quite low. Therefore, it is essential to have procedures in place to keep an eye on the saturated fatty acid level, which has a negative impact on consumers' health. The findings of experimental research demonstrated that trans fatty acids were not present in instant noodle products. It revealed that the food processing sector has advanced favorably and catered to the demands of both the domestic and international markets.
Nanostructured lubricant additives for titanium alloy: Lubrication by the solid-liquid interface with Coulomb repulsion
Authors: Duan Linlin , Jia Dan , Li Jian , Liu Jianfang , Duan Haitao 
Published: March 2024

AbstractIn this work, the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid-liquid nanosized contact interface is taken, and the superior friction-reducing property of Cu3(PO4)2·3H2O (CuP) oil-based additives has been confirmed for titanium alloy. Three-dimensional (3D) CuP nanoflowers (CuP-Fs) with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil. Lubrication by CuP-Fs additives for titanium alloy, friction coefficient (COF) can be reduced by 73.68%, and wear rate (WR) reduced by 99.69%. It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid-liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules. However, any steric hindrance or connection between this repulsive solid-liquid interface will trigger the adhesion and increase the viscous shear force, for example, dispersant, hydrogen bondings, and shaky adsorbed water molecules. Besides, the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties. Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.
Are regime changes always bad economics? Evidence from daily financial data
Authors: Incerti Devin , Incerti Trevor 
Published: March 2024

AbstractPolitical instability is commonly thought to discourage investment and reduce economic growth. We challenge this consensus by showing that instability does not systematically depress investment. Using an event study approach, we examine daily returns of national financial indices in every country that experienced an irregular regime change subject to data availability. Returns following resignations are large and positive (+4 percent), while those following assassinations are negative and smaller in magnitude (−2 percent). The impact of coups tends to be negative (−2 percent), but we show that a pro-business coup results in large positive returns (+10 percent). We also find evidence that authoritarian or anti-business regime changes are more likely to lead to capital flight than democratic or pro-business changes. The immediate impact of political instability on investment is therefore dependent on the type of regime change and its expected impact on future growth.
Constitutionalizing Mass Surveillance in the EU: Civil Society Demands, Judicial Activism, and Legislative Inertia
Authors: Celeste Edoardo , Formici Giulia 
Published: March 2024

AbstractDespite the shock provoked by the Snowden revelations, mass surveillance is still a reality in the EU. However, over the past few years, it has been possible to observe a gradual constitutionalization of these practices. This Article maps the ongoing process of progressively defining the constitutional limits and societal affordances of mass surveillance in the EU by focusing on the three main actors who contribute to it. First, this Article presents civil society as the propeller of this trend. Civil society not only advocated for a ban on general surveillance systems in the aftermath of the Snowden revelations, but also promoted a series of strategic litigations to challenge state surveillance practices at national and EU levels. Second, it analyses CJEU case law as the main constitutionalizing engine of this process. The Court pragmatically ascertained that an absolute prohibition of mass surveillance did not appear to be a realistic solution and put significant effort into actively defining the legal boundaries of these practices by striving to find an equilibrium between Member State interests and citizens’ fundamental rights. Third, it considers the approaches taken by national legislators to be a slowing factor. States are still reluctant to incorporate the constitutional standards progressively developed by courts despite the now significant body of judicially created parameters in the field.
Development of a new magnetic mirror device at the Korea Advanced Institute of Science and Technology
Authors: Oh D. , Choe M. , Baek G. , Kim D. , Jung B. K. , Chung K. J. , Kourakis I. , Sung C. 
Published: March 2024

A new magnetic mirror machine named KAIMIR (KAIST mirror) has been designed and constructed at the Korea Advanced Institute of Science and Technology (KAIST) to study mirror plasma physics and simulate the boundary regions of magnetic fusion plasmas such as in a tokamak. The purpose of this paper is to introduce the characteristics and initial experimental results of KAIMIR. The cylindrical vacuum chamber has a length of 2.48 m and a diameter of 0.5 m and consists of three sub-chambers, namely the source, centre and expander chambers. A magnetic mirror configuration is achieved by electromagnetic coils with a maximum magnetic field strength of 0.4 T at the mirror nozzles and 0.1 T at the centre. The source plasma is generated by a plasma washer gun installed in the source chamber with a pulse forming network system. The typical discharge time is ~12 ms with a ~6 ms (1–7 ms) steady period. Initial results show that the on-axis electron density at the centre is 1019–20 m−3 and the electron temperature is 4–7 eV. Two parameters were varied in this initial phase, the source power and the mirror ratio, which is the ratio of highest to lowest magnetic field strength in the mirror-confined region. We observed that the increase of the electron density was mitigated for a source power above 0.2 MW. It was also found that the electron density increases almost linearly with the mirror ratio. Accordingly, the stored electron energy was also linearly proportional to the mirror ratio, similar to the scaling of the gas dynamic trap.
Temporal trend analysis of acute hepatitis B virus infection in China, 1990–2019
Authors: Han Ying , Li Yuansheng , Wang Shuyuan , Chen Jialu , Zhang Junhui 
Published: March 2024

Abstract
China faces challenges in meeting the World Health Organization (WHO)’s target of reducing hepatitis B virus (HBV) infections by 95% using 2015 as the baseline. Using Global Burden of Disease (GBD) 2019 data, joinpoint regression models were used to analyse the temporal trends in the crude incidence rates (CIRs) and age-standardized incidence rates (ASIRs) of acute HBV (AHBV) infections in China from 1990 to 2019. The age–period–cohort model was used to estimate the effects of age, period, and birth cohort on AHBV infection risk, while the Bayesian age–period–cohort (BAPC) model was applied to predict the annual number and ASIRs of AHBV infections in China through 2030. The joinpoint regression model revealed that CIRs and ASIRs decreased from 1990 to 2019, with a faster decline occurring among males and females younger than 20 years. According to the age–period–cohort model, age effects showed a steep increase followed by a gradual decline, whereas period effects showed a linear decline, and cohort effects showed a gradual rise followed by a rapid decline. The number of cases of AHBV infections in China was predicted to decline until 2030, but it is unlikely to meet the WHO’s target. These findings provide scientific support and guidance for hepatitis B prevention and control.
APPROXIMATE PRICING OF DERIVATIVES UNDER FRACTIONAL STOCHASTIC VOLATILITY MODEL
Authors: HAN Y. , ZHENG X. 
Published: March 2024

AbstractThis paper examines the issue of derivative pricing within the framework of a fractional stochastic volatility model. We present a deterministic partial differential equation system to derive an approximate expression for the derivative price. The proposed approach allows for the stochastic volatility to be expressed as a composition of deterministic functions of time and a fractional Ornstein–Uhlenbeck process. We apply this method to the European option pricing under the fractional Stein–Stein volatility model, demonstrating its feasibility and reliability through numerical simulations. Our numerical simulations also illustrate the impact of the parameters in the fractional stochastic volatility model on the option price.
Qualitative and quantitative comparisons of type 1 macular neovascularizations between pachychoroid neovasculopathy and neovascular age-related macular degeneration using optical coherence tomography angiography
Authors: Yanık Özge , Demirel Sibel , Özcan Gökçen , Batıoğlu Figen , Özmert Emin 
Published: March 2024

Abstract
Objectives
To compare qualitative and quantitative features of type 1 macular neovascularizations (MNV) in pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD).

Methods
Forty-three treatment-naive eyes of 41 PNV patients and 40 treatment-naive eyes of 38 patients with nAMD were included. The patients were classified as PNV or nAMD according to the presence of pachychoroid features and soft/reticular drusen. Presence of central trunk and maturity of the MNV were evaluated on optical coherence tomography angiography (OCTA) images. MNV area, vessel density (VD), total vessel length (VL), number of intersection points (IPs), fractal dimension (FD), and lacunarity (LAC) were calculated using ImageJ software and FracLac plugin.

Results
The mean age was 56.8 ± 8.7 years in PNV and 70.4 ± 8.8 years in neovascular AMD groups (p < 0.001). Compared to nAMD, the presence of central trunk was less frequent in PNV (48.8% vs 77.5%, p = 0.007). Immature MNV pattern was observed more frequently in PNV eyes than nAMD (41.9% vs 20.0%, p = 0.009). PNV cases had significantly lower median MNV area [0.913(1.115) vs 2.542(3.273) mm²], total VL [14.84 (20.46) vs 36.34 (44.68) mm], number of IPs [104(140) vs 335(417.3)], and FD [1.56(0.10) vs 1.59(0.11)] comparing to nAMD cases (p < 0.001, p = 0.001, p < 0.001, p = 0.043 respectively). However, the mean VD (42.4 ± 6.8 vs 42.9 ± 9.0%) and the median LAC values [0.42 (0.09) vs 0.42 (0.09)] did not differ significantly between groups (p = 0.776, p = 0.526, respectively).

Conclusion
Morphological and quantitative differences exist in type 1 neovascular lesions. Type 1 MNVs in the PNV group are characterized by a smaller and less complex structure.