487 research outputs found
Statistical data of all counties and cities in the Yangtze River Delta in 2019.
Statistical data of all counties and cities in the Yangtze River Delta in 2019.</p
Weak Interaction Activates Esters: Reconciling Catalytic Activity and Turnover Contradiction by Tailored Chalcogen Bonding
The
activation of esters by strong Lewis acids via the formation
of covalent adducts is a classic strategy to give reactivity; however,
this approach frequently incurs limited turnover due to the low efficiency
in the dissociation of catalyst from a stable catalyst-product complex.
While the use of some weak interaction catalysts that can easily dissociate
from any bonding complexes in the reaction system would solve this
catalyst turnover problem, the poor catalytic activity in the ester
activation that can be provided by these noncovalent forces in turn
sets up a formidable challenge. Herein, we describe the activation
and catalytic transformation of esters by weak interactions, which
provides a promising platform to reconcile the catalytic activity
and turnover problems. Several tailored chalcogen-bonding catalysts
were developed for the activation of esters, enabling achieving several
inherently low reactive Diels–Alder reactions as well as the
ring-opening polymerization of lactones through weak chalcogen bonding
interactions. This supramolecular catalysis approach is particularly
highlighted by its capability to promote some uncommon Diels–Alder
reactions involving using dienes bearing electron-withdrawing groups
coupled by α,β-unsaturated ester as dienophiles and substrate
incorporating competitive Lewis basic sites, in which typical strong
Lewis acids showed low catalytic efficiency, while representative
hydrogen and halogen bonding catalysts were inactive
Fast Synthesis and Size Control of Gibbsite Nanoplatelets, Their Pseudomorphic Dehydroxylation, and Efficient Dye Adsorption
In this paper, a
simple and fast (4 days) procedure to synthesize colloidal gibbsite
nanoplatelets (NPTs) from a single aluminum alkoxide (aluminum <i>sec</i>-butoxide) as precursor is presented. The introduction
of a preheating step accelerated the precursor’s hydrolysis/peptization
and considerably shortened the overall reaction time while the acid
concentration affected the uniformity of the platelets shape. This
procedure was successfully exploited to rapidly produce gibbsite platelets
of controllable sizes by combination with the seeded growth method.
The use of a single alkoxide precursor induced high growth rates and
allowed a fast control of the platelets size over a wide range (nano-
to microscale after only three growth steps). No signs for size limitation
were observed. The dehydroxylation sequence of the as-synthesized
NPTs was systematically investigated. Thermally stable chi-alumina
NPTs, pseudomorphs of the parent gibbsite platelets, with a micro/mesoporous
structure and high specific surface area, were obtained. The synthesized
gibbsite NPTs can efficiently adsorb Methyl Orange dye in wastewater
treatment with removal efficiency up to 94.8%
Data_Sheet_1_Male infertility risk and gut microbiota: a Mendelian randomization study.docx
BackgroundIn recent decades, the decline of male sperm quality has become a worldwide phenomenon, with sperm quality of critical importance for the ability to conceive naturally. Recent studies suggest that male fertility function is closely linked to the gut microbiota, however, the cause-and-effect association between the gut microbiota and male infertility risk is currently unclear.MethodsWe performed one two-sample Mendelian randomization (MR) study, which uses summary data on human gut microbiota from the MiBioGen consortium as factors of exposure. FinnGen Consortium R8 data was used to obtain GWAS data for male infertility. To evaluate cause-and-effect associations linking gut microbiota and male infertility risk with multiple Mendelian randomization methods, we included inverse variance weighted (IVW), MR-Egger, and Maximum Likelihood (ML) Ratio. The heterogeneity of instrumental variables was evaluated through Cochran's Q, Rucker's Q, and leave-one-out analysis methods.ResultsWe found a positive association between Allisonella, Anaerotruncus, Barnesiella, Intestinibacter, and Lactococcus with male infertility risk according to the MR analysis results. Bacteroides Romboutsia, Ruminococcaceae (NK4A2140group), and Ruminococcaceae (UCG011) play a protective function in male infertility pathogenesis.ConclusionIt was found that gut microbiota and infertility are causally related in this study. In subsequent studies, there is a need to build a larger and more comprehensive GWAS database on male infertility, which will reveal the underlying mechanisms for gut microbiota and male infertility. There is a need for randomized controlled trials for validating the protective effect of the associated gut microbiota against male infertility risk, and for exploring the associated mechanisms.</p
Digital Counting of Breaks Labeling <i>In Situ</i>: A Fast and Absolute Quantification Method for Measurement of DNA Double-Strand Breaks Based on Digital Polymerase Chain Reaction
DNA double-strand break (DSB) is the most dangerous type
of DNA
damage. In addition, DSBs are also common consequences of various
therapeutic and genetic modifications. Therefore, quantification of
DSB is of great importance in many fields including DNA damage repair,
cancer therapy, gene editing, and radiation biology. Current methods
are either low-throughput, laborious, or high cost. Here, we developed
dc-BLIS (digital counting of breaks labeling in situ), a new method that can rapidly and precisely quantify the number
of intracellular DSBs at a low cost by digital polymerase chain reaction.
Using dc-BLIS, we quantified and compared the amount of DSBs induced
by anti-cancer drugs, Cas9 variants, and different radiation doses,
proving the capacity of dc-BLIS to quantify DSBs. We propose that
dc-BLIS is suitable for various application scenes that require rapid
and precise quantification of DSBs, including drug screening, gene-editing
tool modification, and radiation effect assessment
Development of a High-Throughput Resequencing Array for the Detection of Pathogenic Mutations in Osteogenesis Imperfecta
<div><p>Objective</p><p>Osteogenesis imperfecta (OI) is a rare inherited skeletal disease, characterized by bone fragility and low bone density. The mutations in this disorder have been widely reported to be on various exonal hotspots of the candidate genes, including <i>COL1A1</i>, <i>COL1A2</i>, <i>CRTAP</i>, <i>LEPRE1</i>, and <i>FKBP10</i>, thus creating a great demand for precise genetic tests. However, large genome sizes make the process daunting and the analyses, inefficient and expensive. Therefore, we aimed at developing a fast, accurate, efficient, and cheaper sequencing platform for OI diagnosis; and to this end, use of an advanced array-based technique was proposed.</p><p>Method</p><p>A CustomSeq Affymetrix Resequencing Array was established for high-throughput sequencing of five genes simultaneously. Genomic DNA extraction from 13 OI patients and 85 normal controls and amplification using long-range PCR (LR-PCR) were followed by DNA fragmentation and chip hybridization, according to standard Affymetrix protocols. Hybridization signals were determined using GeneChip Sequence Analysis Software (GSEQ). To examine the feasibility, the outcome from new resequencing approach was validated by conventional capillary sequencing method.</p><p>Result</p><p>Overall call rates using resequencing array was 96–98% and the agreement between microarray and capillary sequencing was 99.99%. 11 out of 13 OI patients with pathogenic mutations were successfully detected by the chip analysis without adjustment, and one mutation could also be identified using manual visual inspection.</p><p>Conclusion</p><p>A high-throughput resequencing array was developed that detects the disease-associated mutations in OI, providing a potential tool to facilitate large-scale genetic screening for OI patients. Through this method, a novel mutation was also found.</p></div
Hydrodesulfurization of Dibenzothiophene over MCM-41-Supported Pd and Pt Catalysts
Three series of aluminosilicate MCM-41 (Al-MCM-41) were
synthesized
using different aluminum sources, including aluminum isopropoxide
(AlM-I), pseudoboehmite, and aluminum sulfate, by a hydrothermal method.
The hydrodesulfurization (HDS) performance of the Al-MCM-41-supported
Pd and Pt catalysts prepared with chlorided precursors were evaluated
with dibenzothiophene (DBT) as the model sulfur-containing molecule,
in comparison with those supported on a siliceous MCM-41 (SiM). Pd/SiM
and Pt/SiM were not promising for DBT HDS because of their relatively
low activities and the rapid irreversible deactivation. Pd and Pt
supported on the acidic Al-MCM-41 materials showed higher dispersion
and enhanced HDS performances. AlM-I, which possessed the strongest
acidity, was the most promising among the mesoporous materials investigated.
The deactivated Pd/AlM-I and Pt/AlM-I can be reversibly regenerated
by H<sub>2</sub> reduction. DBT HDS over the Pd catalysts predominantly
took the hydrogenation (HYD) pathway, whereas the direct desulfurization
(DDS) pathway and HYD pathway were comparable for the Pt catalysts.
Increasing the support acidity had no positive effect on the DDS activity
of Pd but significantly enhanced its HYD activity, while the increase
in the rate constant of DDS pathway was close to that of the HYD pathway
for Al-MCM-41-supported Pt catalysts. The effect of the acid properties
of the supports on the HDS performance of Pd and Pt catalysts was
discussed by considering the formation of “electronic-deficient”
particles and the hydrogen spillover process
Image_1_Real-time detection of Seneca Valley virus by one-tube RPA-CRISPR/Cas12a assay.pdf
IntroductionSenecavirus A (SVA) is a highly contagious virus that causes vesicular disease in pigs. At present, laboratory detection methods, such as virus isolation and polymerase chain reaction (PCR), required precision instruments and qualified personnel, making them unsuitable for point-of-care tests (POCT). Fortunately, the emergence of CRISPR/Cas system has provided new opportunities for fast and efficient pathogen detection.MethodsThis study successfully developed a precise and sensitive detection platform for diagnosing SVA by combining the CRISPR system with recombinase polymerase amplification (RPA). ResultsThe minimum detection limit of the assay was 10 copies of the SVA genome. Meanwhile, the assay demonstrated high specificity. To validate the effectiveness of this system, we tested 85 swine clinical samples and found that the fluorescence method had a 100% coincidence rate compared to RT-qPCR. DiscussionOverall, the RPA-CRISPR/Cas12a assay established in our study is a highly effective method for detecting SVA and holds great potential for practical applications in the resource-limited settings.</p
Elevation, historical ignitions (1991–2010), settlements and roads in Longquan.
<p>Elevation, historical ignitions (1991–2010), settlements and roads in Longquan.</p
It is a reverse sequencing for the insertion GAT by direct sequencing.
<p>It is a reverse sequencing for the insertion GAT by direct sequencing.</p
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