Combustion Chemistry and Decomposition Kinetics of Forest Fuels

AbstractA brief review is given of the studies in combustion chemistry and decomposition kinetics of forest fuels (FF). The methods used in the study to investigate the FF pyrolysis kinetics and the combustion of the Siberian forests are described. The experiments on FF pyrolysis were conducted at high heating rates (150K/s) in a flow reactor by the method of differential mass-spectrometric thermal analysis (DMSTA) in situ using probe molecular-beam mass spectrometry, and at low heating rates (0.17K/s) by the thermogravimetric method. The kinetic parameters of Siberian FF pyrolysis have been determined for oxidative and inert media and simulation of FF pyrolysis has been conducted using the multi-component devolatilization mechanism. The flame structure of a pine branch has been studied by probe molecular-beam mass spectrometry. Species have been identified in the dark and luminous flame zones; the width of the flame zone has been measured

Frequency-Domain-Based Function Generation Synthesis for Planar Multi-Loop Mechanisms

This paper presents a novel frequency-domain-based approach for function generation synthesis in planar multi-loop mechanisms featuring two independent kinematic loops. To our knowledge, this is the first extension of frequency-domain-based synthesis to planar multi-loop mechanisms. Leveraging the Orthogonality of Trigonometric Functions, the system of equations is derived using a frequency-domain physical interpretation, and reformulated into an optimization problem that balances constraint accuracy and numerical stability. This formulation enables the direct acquisition of multiple, defect-free solutions. Unlike time-domain methods, the proposed approach greatly reduces circuit and branch defects without requiring complex singularity or defect analysis. In contrast to existing frequency-domain methods limited to four-bar mechanisms with full-cycle crank inputs, it supports both revolute and prismatic joints and allows motion profiles such as trapezoidal or S-curve planning. The method also avoids explicit trajectory specification for each loop by treating the Fourier coefficients of the shared passive joint as unknowns, while using linear constraints and coefficient symmetry to reduce complexity. Its effectiveness is demonstrated through two novel multi-loop finger mechanisms, the Watt II mechanism, and a comparison with a time-domain method, highlighting its practicality and broad applicability

Efficient Black-box Checking of Snapshot Isolation in Databases

Snapshot isolation (SI) is a prevalent weak isolation level that avoids the performance penalty imposed by serializability and simultaneously prevents various undesired data anomalies. Nevertheless, SI anomalies have recently been found in production cloud databases that claim to provide the SI guarantee. Given the complex and often unavailable internals of such databases, a black-box SI checker is highly desirable. In this paper we present PolySI, a novel black-box checker that efficiently checks SI and provides understandable counterexamples upon detecting violations. PolySI builds on a novel characterization of SI using generalized polygraphs (GPs), for which we establish its soundness and completeness. PolySI employs an SMT solver and also accelerates SMT solving by utilizing the compact constraint encoding of GPs and domain-specific optimizations for pruning constraints. As demonstrated by our extensive assessment, PolySI successfully reproduces all of 2477 known SI anomalies, detects novel SI violations in three production cloud databases, identifies their causes, outperforms the state-of-the-art black-box checkers under a wide range of workloads, and can scale up to large-sized workloads.Comment: 20 pages, 15 figures, accepted by PVLD

Analysis of the sulfate permease family in Bursaphelenchus xylophilus in the nematode development and stress adaptation

IntroductionPine wilt disease (PWD), caused by the pine wood nematode (PWN) Bursaphelenchus xylophilus, poses a significant threat to global pine forests. The sulfate permease (SULP) family is essential for sulfate transport, sulfur assimilation and cellular homeostasis, yet it remains uncharacterized in B. xylophilus. This study aimed to comprehensively identify all members of the SULP family in B. xylophilus and to elucidate their roles in nematode development and stress adaptation.MethodsThrough genomic data analysis, we identified 10 members of the SULP family in B. xylophilus and conducted a comprehensive characterization of their physicochemical properties, conserved motifs, protein structures, and gene expression profiles across different developmental stages.ResultsThe results revealed Bx-sulps were located on 5 chromosomes of B. xylophilus. Phylogenetic analysis unveiled both conserved and divergent evolutionary patterns of these proteins compared to counterparts in other nematodes. Expression analysis demonstrated upregulation of Bx-sulps during the dauer third-instar larva (D3) stage, suggesting their involvement in stress response and diapause. Moreover, certain Bx-sulps exhibited high expression levels in adult stages, indicating a potential role in reproductive processes.DiscussionThe study presents the first comprehensive examination of BxSULP family, shed light on its significance in nematode development and stress adaptation. These findings provide the groundwork for further functional investigations and may aid in the development of targeted strategies for managing PWD

Delta/Lambda Chirality: From Enantiomers to Diastereomers in Heterometallic Complexes with Chelating Ligands

The Δ/Λ chirality observed in octahedral molecules with chelating ligands represents the major group of “chiral-at-metal” complexes. Upon shifting from mononuclear to polynuclear systems with multiple (≥2) chiral centers, not only enantiomers but also diastereomers should be considered. We present the first, to the best of our knowledge, diastereomeric pairs Δ,Δ,Δ/Λ,Λ,Λ (1) and Δ,Δ,Λ/Λ,Λ,Δ (2) of the pentanuclear assembly [MnII(ptac)3–Na-CoIII(acac)3–Na-MnII(ptac)3] (ptac = 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionate; acac = acetylacetonate). Diastereomers 1 and 2 were isolated in pure form and found to exhibit distinctly different structural characteristics. Importantly, for compounds that are applied as single-source precursors for the quaternary oxide cathode material P2–Na0.67Mn0.67Co0.33O2, the diastereomers revealed different thermal behaviors in terms of volatility and thermal stability. Unambiguous assignment of the Mn and Co positions in both diastereomers has been confirmed by the synchrotron X-ray resonant diffraction technique. Oxidation states of metal ions have been verified by the synchrotron X-ray fluorescence spectroscopy. The diastereomerization between 1 and 2 is not taking place in the solid state (crystal-to-crystal), as well as in the gas phase. The transformation between two diastereomers was observed in the solutions of noncoordinating solvents and was related to the polarities of the solvents and diastereomeric molecules

Microplastics and nanoplastics in cardiovascular disease—a narrative review with worrying links

With the widespread use of plastic products and the increase in waste, microplastics and nanoplastics (MNPs) have become an important issue in global environmental pollution. In recent years, an increasing number of studies have shown that MNPs may have negative impacts on human health. This review aimed to explore the association between MNPs and cardiovascular disease and provide an outlook for future research. Research has shown that there may be a link between MNPs exposure and cardiovascular disease. Laboratory studies have shown that animals exposed to MNPs often exhibit abnormalities in the cardiovascular system, such as increased blood pressure, vascular inflammation, and myocardial damage. Epidemiological surveys have also revealed that people exposed to MNPs are more likely to suffer from cardiovascular diseases, such as hypertension and myocardial infarction. Although the specific impact mechanism is not fully understood, there are several possible pathways of action, including the effects of toxic substances on MNPs and interference with the endocrine system. In summary, MNPs exposure may have a negative impact on cardiovascular health, but further research is needed to confirm its specific mechanism and extent of impact to guide relevant public health and environmental policies

Heterometallic Molecular and Ionic Isomers

Numerous descriptions of structural isomerism in metal complexes do not list any molecular vs ionic isomers. At the same time, one of the most striking examples of structural isomerism in organic chemistry is molecular urea, which has the same atomic composition as the chemically distinct ionic ammonium cyanate. This iconic organic couple now meets its inorganic heterometallic counterpart. We introduce a new class of structural isomers, molecular vs ionic, that can be consummated in complex and coordinatively unsaturated polynuclear/heterometallic compounds. We report inorganic molecular and ionic isomers of the composition [NaCrFe (acac)3(hfac)3] (acac = acetylacetonate; hfac = hexafluoroacetylacetonate). Heterometallic molecular [CrIII(acac)3-Na-FeII(hfac)3] (1m) and ionic {[CrIII(acac)3-Na-CrIII(acac)3]+[FeII(hfac)3-Na-FeII(hfac)3]−} (1i) isomers have been isolated in pure form and characterized. While both ions are heterobimetallic trinuclear entities, the neutral counterpart is a heterotrimetallic trinuclear molecule. The two isomers exhibit distinctly different characteristics in terms of solubility, volatility, mass spectrometry ionization, and thermal behavior. Unambiguous assignment of the positions and oxidation/spin states of the Periodic Table neighbors, Fe and Cr, in both isomers have been made by a combination of characterization techniques that include synchrotron X-ray resonant diffraction, synchrotron X-ray fluorescence spectroscopy, Mössbauer spectroscopy, and DART mass spectrometry. The transformation between the two isomers that does take place in solutions of noncoordinating solvents has also been tested

Simplified methods for variance estimation in microbiome abundance count data analysis.

The complex nature of microbiome data has made the differential abundance analysis challenging. Microbiome abundance counts are often skewed to the right and heteroscedastic (also known as overdispersion), potentially leading to incorrect inferences if not properly addressed. In this paper, we propose a simple yet effective framework to tackle the challenges by integrating Poisson (log-linear) regression with standard error estimation through the Bootstrap method and Sandwich robust estimation. Such standard error estimates are accurate and yield satisfactory inference even if the distributional assumption or the variance structure is incorrect. Our approach is validated through extensive simulation studies, demonstrating its effectiveness in addressing overdispersion and improving inference accuracy. Additionally, we apply our approach to two real datasets collected from the human gut and vagina, respectively, demonstrating the wide applicability of our methods. The results highlight the efficacy of our covariance estimators in addressing the challenges of microbiome data analysis. The corresponding software implementation is publicly available at https://github.com/yimshi/robustestimates