Various 1,1-disubstituted terminal olefins have been investigated for asymmetric epoxidation using chiral ketone catalysts. Up to 88% ee has been achieved with a lactam ketone, and a planar ...transition state is likely to be a major reaction pathway.
populations exhibit genetic and phenotypic variations, particularly in terms of copper tolerance. Group I strains of
generally exhibit higher copper tolerance compared to group II strains. This study ...aims to identify genes involved in copper tolerance to better understand the differences in copper tolerance between group I and group II strains. Representative strains pslb65 (group I) and pslbtw14 (group II) were selected for comparison. Deletion mutants of putative copper-tolerance genes and their corresponding complementary strains were constructed. The copper tolerance of each strain was evaluated using the minimum inhibitory concentration method. The results showed that the
,
,
, and
genes played major roles in copper tolerance in
, while
-like,
-like, and
-like genes had minor effects. The different expression levels of copper-tolerance-related genes in pslb65 and pslbtw14 under copper stress indicated that they had different mechanisms for coping with copper stress. Overall, this study provides insights into the mechanisms of copper tolerance in
and highlights the importance of specific genes in copper tolerance.
Microbial populations and their relationship to bioconversion during lignocellulosic waste composting were studied by quinone profiling. Nine quinones were observed in the initial composting ...materials, and 15 quinones were found in compost after 50
days of composting. The quinone species Q-9(H2), Q-10 and Q-10(H2) which are indicative of certain fungi appeared at the thermophilic stage but disappeared at the cooling stage. Q-10, indicative of certain fungi, and MK-7, characteristic of certain bacteria, were the predominant quinones during the thermophilic stage and were correlated with lignin degradation at the thermophilic stage. The highest lignin degradation ratio (26%) and good cellulose degradation were found at the cooling stage and were correlated with quinones Q-9, MK-7 and long-chain menaquinones attributed to mesophilic fungi, bacteria and actinomycetes, respectively. The present findings will improve the understandings of microbial dynamics and roles in composting, which could provide useful references for development of composting technology.
Objective: As a frequent hypertensive disorder in pregnancy, preeclampsia causes 15% of all preterm deliveries. This study aims to understand its mechanism via analyzing gene expression and ...methylation data.
Methods: Human gene expression microarray data (GSE73374) and corresponding DNA methylation microarray data (GSE73375) of preeclamptic placental tissues (n = 19) and normotensive placental tissues (n = 17) were obtained from the Gene Expression Omnibus. Differentially expressed genes (DEGs), differentially methylated regions (DMRs) and CpG islands (DMIs) were identified and compared. Pathway enrichment analysis was performed, and the functional interactions were investigated.
Results: A total of 392 DEGs, 2667 DMRs, and 464 DMIs were found between the two groups, and a functional interaction network of DEGs was established. Then, 28 potential key genes were identified, which were oppositely regulated in preeclampsia regarding expression and methylation. Eight of the potential key genes had DMIs, among which ITGA5 interacted with FN1 and FOS. The 3 DEGs were up-regulated, and their DMIs were hypomethylated.
Conclusion: FN1, FOS, and ITGA5 might promote the development of preeclampsia via modulating differentiation/apoptosis/invasion of human extravillous trophoblasts, as well as focal adhesion, VEGFR3 signaling, β1 integrin cell surface interactions, α9β1/α4β1 integrin signaling, AP-1/ATF-2/HIF-1α transcription factor networks, and Fc-epsilon receptor I signaling in mast cells.
Chinese sturgeon was an endangered cartilaginous fish. The success of artificial breeding has promoted it to a food fish and it is now beginning to provide a new source of cartilage for the ...extraction of chondroitin sulfate (CS). However, the structural characteristics of sturgeon CS from different tissues remain to be determined in more detail. In this study, CSs from the head, backbone, and fin cartilage of Chinese sturgeon were individually purified and characterized for the first time. The molecular weights, disaccharide compositions, and oligosaccharide sulfation patterns of these CSs are significantly different. Fin CS (SFCS), rich in GlcUAα1-3GalNAc(4S), has the biggest molecular weight (26.5 kDa). In contrast, head CS (SHCS) has a molecular weight of 21.0 kDa and is rich in GlcUAα1-3GalNAc(6S). Most features of backbone CS (SBCS) are between the former two. Other glycosaminoglycan impurities in these three sturgeon-derived CSs were lower than those in other common commercial CSs. All three CSs have no effect on the activity of thrombin or Factor Xa in the presence of antithrombin III. Hence, Chinese sturgeon cartilage is a potential source for the preparation of CSs with different features for food and pharmaceutical applications.
Attention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental disorders in childhood. Numerous resting-state functional magnetic resonance imaging (rs-fMRI) studies in ...ADHD have been performed using traditional low-frequency bands (0.01–0.08 Hz). However, the neural activity patterns of frequency subbands in ADHD still require further investigation. The purpose of this study is to explore the frequency-dependent characteristics and neural activity patterns of ADHD subtypes. We selected the ADHD combined type (ADHD-C, N = 25), ADHD inattentive type (ADHD-I, N = 26) and typically developing (TD, N = 28) children from the ADHD-200 Consortium. Based on the slow-5 band (0.01–0.027 Hz) and slow-4 band (0.027–0.073 Hz), we generated static and dynamic fractional amplitude of low-frequency fluctuation (fALFF) and regional homogeneity (ReHo) maps for each participant. A flexible-factorial analysis of variance model was performed on static and temporal dynamic rs-fMRI measurements within two subbands. Results revealed that the orbital-frontal gyrus, precuneus, superior temporal gyrus and angular gyrus were found to have obvious frequency band and group interaction effects. The intrinsic neural activity differences among three groups were more prominent in the slow-5 frequency band compared to the slow-4 band. In addition, the indices of significant interaction regions showed correlations with the progression of the disease and the features in slow-5 showed an advantageous diagnostic performance compared with those in slow-4. The results suggested the intrinsic neural activities of ADHD subtypes were frequency-dependent. The frequency-specific analysis of static and dynamic brain activity may provide a deeper understanding of neurophysiological dysfunction patterns in ADHD subtypes and provide supplementary information for assessing ADHD subtypes.
Waste cellulosic biomass obtains various applications due to low-cost and eco-benign characteristics. A general strategy is proposed for waste cellulosic biomass to be modified with dialdehyde ...functional groups as intermediates through periodate partial oxidation. Finally, aminothiourea-modified waste cellulosic biomass can be prepared through Schiff reaction. Waste corn stalk, cotton and paper as typical precursors, were used to prepare cellulosic biomass, abbreviated as AT-S, AT-C and AT-P, respectively, and their adsorption behaviors of Au(III) from the hydrochloric acid medium were investigated. The pseudo-second kinetics equation as well as the Langmuir isotherm equation can be used to depict the adsorption process, and the maximum adsorption capacities of Au(III) are 21.4, 19.0 and 3.28 mol/kg for AT-S, AT-C and AT-P at 298 K, respectively. The adsorption capacities of Au(III) on aminothiourea modified corn stalk (AT-S) is almost 357 times greater than that of raw corn stalk. To the best of our knowledge, AT-S has the highest adsorption capacity towards Au(III). AT-S also displays a superior separation selectivity towards Au(III) in the presence of Cu(II), Ni(II), Co(II), Pt(VI), Pd(II) and Rh(III). Furthermore, the characterization analysis of XRD, TG, SEM, TEM and FTIR confirms that AuCl
4
–
has been reduced to elemental Au nanoparticles and deposit onto the surface of the biomass. It shows a prospect for waste corn stalk to be used to adsorb Au(III) from liquid phase and the possible fabrication of gold nanoparticles by a general adsorption process without any reductant.
In this work, Al(OH)3 nanosheets are synthesized in situ on the surface of an Al-20Si alloy via the water bath method, and Al–20Si@Al2O3 composites are then obtained after calcination. The growth ...mechanism of the Al(OH)3 nanosheets is revealed, and a pathway is demonstrated to obtain Al–20Si@Al2O3 nanosheets with the desired structure and thickness. Furthermore, the influence of different Al–20Si@Al2O3 contents on the primary silicon phase in the Al–20Si alloy is investigated, and the mechanism of such an influence is theoretically analyzed. The mechanical properties of the modified Al–20Si alloy are tested, and the effects of the morphology and particle size of the silicon phase on the alloy properties are studied. The results show that Al–20Si@Al2O3 synthesized in situ by water bath has good dispersion in the melt. There is a lot of γ-Al2O3 dispersed in the matrix of the alloy, and the primary silicon of the Al-20Si alloy is obviously refined. By increasing the content of the modifier, the average size of primary silicon decreases first and then increases. When 15 wt% of the modifier is added, the refinement effect of primary silicon reaches its peak, and the size of primary silicon is reduced from unmodified 86.4 μm to 28.5 μm. The hardness and tensile strength of 75.2 HB and 120.3 MPa are increased to 107.2 HB and 185.9 Mpa by 42% and 55%, respectively. Compared with adding γ-Al2O3 directly, this experiment provides a simple method to synthesize the modifier, and γ-Al2O3 can be dispersed evenly in the aluminium-silicon alloy melt more easily by in-situ generation, without ultrasonic treatment or other ways. During mass production, the cost can be better controlled and good results can be achieved at the same time.
Atmospheric rivers (ARs) are long, narrow bands of enhanced water vapour transport in the low atmosphere, mainly from the tropics into the midlatitudes. However, it is still unclear how ARs act on ...different timescales during the boreal summer when frequent heavy precipitation events take place in East Asia, often resulting in severe flood that impacts property and human lives. In this study, we investigated climatological ARs, and their evolution on both synoptic and subseasonal timescales, associated with heavy rainfall events over the Yangtze Plain in China. Furthermore, their predictability was assessed by examining hindcast skills from an operational coupled seasonal forecast system of the Australian Bureau of Meteorology named ACCESS-S1. Results showed that ARs embedded within the South Asian monsoon and Somali cross-equatorial flow provide a favourable background for steady moisture supply of summer rainfall into East Asia. We call this favourable background a ‘climatological East Asian AR’, which has close connections with seasonal cycles and climatological intraseasonal oscillation of rainfall in the Yangtze Plain during its Meiyu season. The East Asian AR was also influenced by anomalous anticyclonic circulations over the tropical West Pacific when heavy rainfall events occurred over the Yangtze Plain. Different from orography-induced precipitation, ARs that led to heavy rainfall over the Yangtze Plain were linked with the intrusions of cold air from the north. The major source of ARs responsible for heavy precipitation events over the Yangtze Plain appeared to originate from the tropical West Pacific on both synoptic and subseasonal timescales. In 23-year hindcasts for May-June-July the current model, ACCESS-S1, had skillful rainfall forecasts at a lead time of 0 month, but the skill degraded significantly with longer lead times. Nevertheless, the model showed skills in predicting the variations of low-level moisture transport affecting the Yangtze River at longer lead time, suggesting that the ARs influencing summer monsoon rainfall in the East Asian region are likely to be more predictable than rainfall itself. There is potential in using AR predictions from the coupled forecast system to guide rainfall forecasts in the East Asian summer season at longer lead time, which can contribute to disaster prevention and reduction in East Asia.
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