bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThe 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

AbstractPanax 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

AbstractFrom 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

AbstractA 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

AbstractIn 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

AbstractA 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

AbstractThis 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

AbstractDecolorization 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

AbstractIn 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

AbstractThis 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

AbstractWe 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

AbstractElectrotactile 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

AbstractClinical 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

AbstractThe 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

AbstractVariants 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.