Oxidation-induced starch molecular degradation:A comprehensive kinetic investigation using NaClO/NaBr/TEMPO system

Starch degradation often coincides with its chemical modification, and understanding how chemical modification influences starch degradation is vital for determining the properties of the resultant modified products. This work investigates the effect of oxidation on starch molecular degradation, examining factors such as oxidation degree, reaction kinetics, and degradation patterns during 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated starch oxidation under varying conditions, including reaction time, pH, temperature, and concentrations of NaBr, TEMPO, and NaClO. Results emphasize that extended reaction durations primarily lead to β-elimination, causing α-1,4 linkage cleavages. pH 8.5 favored non-selective oxidation, while pH 11 enhanced β-elimination, both slowing the reaction rate and severely damaging starch chains (Mw of 8.8 × 105 g/mol and 7.2 × 105 g/mol, respectively). Elevated temperature from 0 to 30 °C significantly expedited both selective and non-selective oxidation, dramatically reducing molecular mass to 8.1 × 105 g/mol. Increasing concentrations of NaBr and TEMPO boost the reaction rate with minimal impact on molecular mass. Meanwhile, increasing NaClO concentration from 0.2 to 2.2 mmol/g-starch not only affects the reaction rate but also reinforces β-elimination, enhancing molecular degradation. This study is insightful for starch modification to achieve desired oxidation levels and chain lengths by controlling reaction conditions, offering potential advancements in oxidized starch-based materials like nano micelles

Genetic testing and microstructure characterization of biological crusts on the rammed soil surface at the Shanhaiguan great wall in China

Protection of cultural relics and sites is of great significance. In this study, the new gray-green thin-layer biological crust on the rammed soil surface at the Shanhaiguan Great Wall in China was found. The emergence of this material has substantially improved the resistance of the rammed Earth Great Wall to rain erosion. 16S rRNA gene sequencing on the surface crusts of rammed Earth was performed. Results show the biological crusts were mainly algae-based composite crusts containing fungi. At the genus level, microalgae and Sphingomycetes were predominant. Under scanning electron microscopy (SEM), algae filaments dominated by filamentous algae overlapped and intertwined with each other. Furthermore, polysaccharide organic matter secreted by algae formed a covering film. The two formed a complex spatial network structure to envelop soil particles, which enhances erosion resistance. The conformable biological crusting is expected to be used as a new civil engineering material for the protection of rammed Earth sites in the future

A CsI hodoscope on CSHINE for Bremsstrahlung {\gamma}-rays in Heavy Ion Reactions

Bremsstrahlung $\gamma$ production in heavy ion reactions at Fermi energies carries important physical information including the nuclear symmetry energy at supra-saturation densities. In order to detect the high energy Bremsstrahlung $\gamma$ rays, a hodoscope consisting of 15 CsI(Tl) crystal read out by photo multiplier tubes has been built, tested and operated in experiment. The resolution, efficiency and linear response of the units to $\gamma$ rays have been studied using radioactive source and $({\rm p},\gamma)$ reactions. The inherent energy resolution of $1.6\%+2\%/E_{\gamma}^{1/2}$ is obtained. Reconstruction method has been established through Geant 4 simulations, reproducing the experimental results where comparison can be made. Using the reconstruction method developed, the whole efficiency of the hodoscope is about $2.6\times 10^{-4}$ against the $4\pi$ emissions at the target position, exhibiting insignificant dependence on the energy of incident $\gamma$ rays above 20 MeV. The hodoscope is operated in the experiment of $^{86}$Kr + $^{124}$Sn at 25 MeV/u, and a full $\gamma$ energy spectrum up to 80 MeV has been obtained.Comment: 9 pages, 19 figure

The Sihailongwan Maar Lake, northeastern China as a candidate Global Boundary Stratotype Section and Point for the Anthropocene Series

Sihailongwan Maar Lake, located in Northeast China, is a candidate Global boundary Stratotype Section and Point (GSSP) for demarcation of the Anthropocene. The lake’s varved sediments are formed by alternating allogenic atmospheric inputs and authigenic lake processes and store a record of environmental and human impacts at a continental-global scale. Varve counting and radiometric dating provided a precise annual-resolution sediment chronology for the site. Time series records of radioactive (239,240Pu, 129I and soot 14C), chemical (spheroidal carbonaceous particles, polycyclic aromatic hydrocarbons, soot, heavy metals, δ13C, etc), physical (magnetic susceptibility and grayscale) and biological (environmental DNA) indicators all show rapid changes in the mid-20th century, coincident with clear lithological changes of the sediments. Statistical analyses of these proxies show a tipping point in 1954 CE. 239,240Pu activities follow a typical unimodal globally-distributed profile, and are proposed as the primary marker for the Anthropocene. A rapid increase in 239,240Pu activities at 88 mm depth in core SHLW21-Fr-13 (1953 CE) is synchronous with rapid changes of other anthropogenic proxies and the Great Acceleration, marking the onset of the Anthropocene. The results indicate that Sihailongwan Maar Lake is an ideal site for the Anthropocene GSSP

Literature analysis on asparagus roots and review of its functional characterizations

Asparagus root (AR) is utilized globally as a traditional herbal medicine because it contains various bioactive compounds, such as polyphenols, flavonoids, saponins, and minerals. The composition profiles of AR are strongly affected by its botanical and geographical origins. Although minerals and heavy metals are minor constituents of AR, they play a crucial role in determining its quality and efficacy. A comprehensive classification of AR, its phytochemistry, and its pharmacology were reviewed and interpreted herein. Potentially eligible articles (in English) were identified through an electronic search of the Web of Science database (2010–2022) and Google (2001–2022). We used the primary search term “Asparagus roots” combined with the words “pharmacology,” “bioactive compounds,” “physicochemical properties,” and “health benefits” to find the relevant literature. We screened the titles, keywords, and abstracts of the publications obtained from the database. A full copy of the article was obtained for further assessment if deemed appropriate. Different asparagus species might potentially be used as herbal medicines and functional foods. Phytochemical studies have revealed the presence of various bioactive compounds as valuable secondary metabolites. The dominant class of bioactive compounds in AR is flavonoids. Furthermore, AR displayed significant pharmacological effects, such as antioxidant, antimicrobial, antiviral, anticancer, anti-inflammatory, and antidiabetic effects, as shown in animal and human studies. This review provides a valuable resource to enable a thorough assessment of the profile of Asparagus root as a functional ingredient for the pharmaceutical and food industries. In addition, it is anticipated that this review will provide information to healthcare professionals seeking alternative sources of critical bioactive compounds

Overexpression of MdARD4 Accelerates Fruit Ripening and Increases Cold Hardiness in Tomato

Ethylene plays an important role in stress adaptation and fruit ripening. Acireductone dioxygenase (ARD) is pivotal for ethylene biosynthesis. However, the response of ARD to fruit ripening or cold stress is still unclear. In this study, we identified three members of Malus ARD family, and expression profile analysis revealed that the transcript level of MdARD4 was induced during apple fruit ripening and after apple plants were being treated with cold stress. To investigate its function in cold tolerance and fruit ripening, MdARD4 was ectopically expressed in Solanum lycopersicum cultivar ‘Micro-Tom’, which has been considered as an excellent model plant for the study of fruit ripening. At the cellular level, the MdARD protein expressed throughout Nicotiana benthamiana epidermal cells. Overexpression of MdARD4 in tomato demonstrated that MdARD4 regulates the ethylene and carotenoid signaling pathway, increases ethylene and carotenoid concentrations, and accelerates fruit ripening. Furthermore, MdARD4 increased the antioxidative ability and cold hardiness in tomato. To conclude, MdARD4 may potentially be used in apple breeding to accelerate fruit ripening and increase cold hardiness

Interactions between Two Deformable Droplets in Tandem Fixed in a Gas Flow Field of a Gas Well

Knowing the droplet-deformation conditions, the droplet-breakup conditions, and the drag force in the interaction between two droplets with a high Reynolds number is of importance for tracking droplet movement in the annular flow field of a gas well. The interactions between two droplets with a high Reynolds number in a tandem arrangement fixed in flowing gas was investigated. The volume of fluid (VOF) method was used to model the droplets’ surface structure. Two different body forces were exerted on both droplets to hold them suspended at a fixed location, which eliminated the effect of droplet acceleration or deceleration on the drag and decreased the amount of computation required. The exerted body forces were calculated using the Newton iteration procedure. The interactions between the two droplets were analyzed by comparison with the simulation results of a single isolated droplet. The effect of the separation distance on the drag force was investigated by changing the separation spacing. The simulation results showed that for droplets with a small separating space between them, the dynamics of the downstream droplet were influenced significantly by the upstream droplet. The drag coefficient of the downstream droplet decreased considerably to a small, even negative, value, especially for droplets with higher Weber numbers and smaller initial separating spaces between them, while the drag force of the upstream droplet was influenced only slightly. In addition, a formula for predicting the final drag coefficient of the downstream droplet was devised

Enantioselective organocatalytic synthesis of axially chiral aldehyde-containing styrenes via SNAr reaction-guided dynamic kinetic resolution

Abstract The precise and efficient construction of axially chiral scaffolds, particularly toward the aryl-alkene atropoisomers with impeccably full enantiocontrol and highly structural diversity, remains greatly challenging. Herein, we disclose an organocatalytic asymmetric nucleophilic aromatic substitution (SNAr) reaction of aldehyde-substituted styrenes involving a dynamic kinetic resolution process via a hemiacetal intermediate, offering a novel and facile way to significant axial styrene scaffolds. Upon treatment of the aldehyde-containing styrenes bearing (o-hydroxyl)aryl unit with commonly available fluoroarenes in the presence of chiral peptide-phosphonium salts, the SNAr reaction via an exquisite bridged biaryl lactol intermediate undergoes smoothly to furnish a series of axially chiral aldehyde-containing styrenes decorated with various functionalities and bioactive fragments in high stereoselectivities (up to >99% ee) and complete E/Z selectivities. These resulting structural motifs are important building blocks for the preparation of diverse functionalized axial styrenes, which have great potential as efficient and privileged chiral ligands/catalysts in asymmetric synthesis