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1.
J Am Chem Soc ; 146(31): 21922-21931, 2024 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-39052980

RESUMO

Donor-acceptor (D-A) conjugated systems have been extensively investigated and play important roles in organic electronics. Incorporating D-A structures into (hetero)cycloarenes endows them tunable electronic properties, while the well-defined cavity remains. However, the synthetic complexity of introducing electron-acceptor moieties into (hetero)cycloarenes limits their development and applications. In this paper, the first family of electronically tunable D-A heterocycloarenes (DAHCn, n = 1-5) based on pyrazine derivatives was facilely synthesized through cyclocondensation reaction from a tetraketone-functionalized heterocycloarene precursor prepared using the ketal-protection strategy. The effect of expanded conjugation and the inserted electron-withdrawing group on the electronic structures of the D-A heterocycloarenes was studied systematically by X-ray crystallographic analysis, various spectroscopic measurements, and theoretical calculations. Interestingly, the presence of an electron-withdrawing group polarizes the inner C(sp2)-H and significantly increases the binding affinities of D-A heterocycloarenes to the iodide anion. Meanwhile, the anion affinity can be further modulated by the type of attached substituents and the distance of polarization. More importantly, the dicyanopyrazine derivative DAHC3 shows the highest binding strength to the iodide ion as a 2:1 sandwich complex (log ß2 = 12.3 and ΔG = -69.1 kJ mol-1), which is the strongest iodide receptor using C(sp2)-H hydrogen bonding interactions reported to date. Our finding provides a new strategy to design and synthesize D-A heterocycloarenes and strong anion receptors.

2.
J Org Chem ; 89(7): 4523-4529, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38502930

RESUMO

Three new donor-acceptor-donor (D-A-D) architecture regioisomers comprising a large planar electron-withdrawing core tribenzo[a,c,i]phenazine and two identical electron-donating triphenylamines with different substitution patterns were designed and synthesized. Employing this regioisomerization strategy, the intramolecular charge-transfer interactions are effectively tuned and result in a significant bathochromic shift of photoluminescence maximum over 100 nm, which induces the corresponding emission band extending into the near-infrared region as well as giving a high solid-state quantum yield of 25%. Meanwhile, it is found that the supramolecular interactions of this series of regioisomers with planar electron-donor pyrene are greatly affected by the substitution pattern.

3.
Phys Chem Chem Phys ; 26(24): 17240-17254, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38856165

RESUMO

For precipitation-strengthened Al alloys, the interfacial segregation behavior of alloying elements plays an important role in controlling the effectiveness of precipitation strengthening. In this work, the adhesion work (Wad) and interfacial energy (γ) of the η(0001)/Al(111) interface were studied to gain an insight into the interface properties between the precipitate η and the Al matrix. Additionally, we examined the impact of the segregation behavior of alloyed elements on the bonding strength of the interface. The computed values for Wad and interfacial energies indicated that the T6S3 terminated configuration represents the interfacial structure with the highest stability across all models analyzed. Focusing on the T6S3 interface, the assessed segregated energies (Eseg) disclose that the segregation ability of elements from strong to weak exhibits the order of Ti > Sc > Zr > Y > Ta > Nb > Lu > Hf > Mo > V > W, while Cr and Mn elements are not easy to segregate at the interface. Sc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, and Ta preferentially occupy Al atoms, whereas Y and Lu predominantly inhabit Mg atoms. Relative to the clean interface, the electron cloud enrichment at the interface after alloying element X (Zr, Sc, Ti, W, Hf, Mn, Y, Lu and V) doping is weakened, and the ion interaction among interface atoms is enhanced. After doping alloying element X (Nb, Mo, Ta, and Cr), the degree of electron cloud enrichment at the interface is obviously enhanced, and the covalent interaction among interface atoms is enhanced. This suggests that the introduction of alloyed elements through doping can augment the bond strength at the interface between the precipitated phase and matrix, thereby reinforcing the strength and toughness of 7xxx series alloys.

4.
Appl Microbiol Biotechnol ; 108(1): 214, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38363425

RESUMO

Glucosylglycerol (GG) is a natural compatible solute that can be synthesized by many cyanobacteria and a few heterotrophic bacteria under high salinity conditions. In cyanobacteria, GG is synthesized by GG-phosphate synthase and GG-phosphate phosphatase, and a hydrolase GGHA catalyzes its degradation. In heterotrophic bacteria (such as some Marinobacter species), a fused form of GG-phosphate phosphatase and GG-phosphate synthase is present, but the cyanobacteria-like degradation pathway is not available. Instead, a phosphorylase GGP, of which the coding gene is located adjacent to the gene that encodes the GG-synthesizing enzyme, is supposed to perform the GG degradation function. In the present study, a GGP homolog from the salt-tolerant M. salinexigens ZYF650T was characterized. The recombinant GGP catalyzed GG decomposition via a two-step process of phosphorolysis and hydrolysis in vitro and exhibited high substrate specificity toward GG. The activity of GGP was enhanced by inorganic salts at low concentrations but significantly inhibited by increasing salt concentrations. While the investigation on the physiological role of GGP in M. salinexigens ZYF650T was limited due to the failed induction of GG production, the heterologous expression of ggp in the living cells of the GG-producing cyanobacterium Synechocystis sp. PCC 6803 significantly reduced the salt-induced GG accumulation. Together, these data suggested that GGP may represent a novel pathway of microbial GG catabolism. KEY POINTS: • GGP catalyzes GG degradation by a process of phosphorolysis and hydrolysis • GGP-catalyzed GG degradation is different from GGHA-based GG degradation • GGP represents a potential novel pathway of microbial GG catabolism.


Assuntos
Glucosídeos , Fosforilases , Synechocystis , Fosforilases/química , Monoéster Fosfórico Hidrolases/genética , Fosfatos
5.
Int J Mol Sci ; 25(5)2024 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-38473942

RESUMO

Plant architecture is one of the key factors affecting maize yield formation and can be divided into secondary traits, such as plant height (PH), ear height (EH), and leaf number (LN). It is a viable approach for exploiting genetic resources to improve plant density. In this study, one natural panel of 226 inbred lines and 150 family lines derived from the offspring of T32 crossed with Qi319 were genotyped by using the MaizeSNP50 chip and the genotyping by sequence (GBS) method and phenotyped under three different environments. Based on the results, a genome-wide association study (GWAS) and linkage mapping were analyzed by using the MLM and ICIM models, respectively. The results showed that 120 QTNs (quantitative trait nucleotides) and 32 QTL (quantitative trait loci) related to plant architecture were identified, including four QTL and 40 QTNs of PH, eight QTL and 41 QTNs of EH, and 20 QTL and 39 QTNs of LN. One dominant QTL, qLN7-2, was identified in the Zhangye environment. Six QTNs were commonly identified to be related to PH, EH, and LN in different environments. The candidate gene analysis revealed that Zm00001d021574 was involved in regulating plant architecture traits through the autophagy pathway, and Zm00001d044730 was predicted to interact with the male sterility-related gene ms26. These results provide abundant genetic resources for improving maize plant architecture traits by using approaches to biological breeding.


Assuntos
Estudo de Associação Genômica Ampla , Zea mays , Zea mays/genética , Melhoramento Vegetal , Mapeamento Cromossômico , Fenótipo , Perfilação da Expressão Gênica , Ligação Genética
6.
Angew Chem Int Ed Engl ; : e202411415, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38990843

RESUMO

Synthesis of fully fused π-conjugated cycloarenes embedded nonbenzenoid aromatics is challenging. In this work, the first example of four-membered ring-embedded cycloarene (MF2) was designed and synthesized in single-crystal form by macrocyclization and ring fusion strategies. For comparison, single bond-linked chiral macrocycle MS2 without two fused four-membered rings and its linear-shaped polycyclic benzenoid monomer L1 were also synthesized. The pronounced anti-aromaticity of four-membered rings significantly adjusts the electronic structures and photophysical properties of cycloarene, resulting in an enhancement of the photoluminescence quantum yield (PLQY) from 10.66% and 10.74% for L1 and MS2, respectively, to 54.05% for MF2, which is the highest PLQY among the reported cycloarenes. Notably, owing to the embedded four-membered rings that reduce structural displacements, MF2 exhibits an ultra-narrowband emission with a single-digit full-width at half-maximum (FWHM) of only 7 nm (0.038 eV), which sets a new record among all reported organic narrowband luminescent molecules, and represents the first example of ultra-narrowband emission in conventional polycyclic aromatic hydrocarbons (PAHs) devoid of heteroatoms.

8.
Microorganisms ; 12(5)2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38792770

RESUMO

In cyanobacteria and chloroplasts (in algae and plants), ATP synthase plays a pivotal role as a photosynthetic membrane complex responsible for producing ATP from adenosine diphosphate and inorganic phosphate, utilizing a proton motive force gradient induced by photosynthesis. These two ATP synthases exhibit similarities in gene organization, amino acid sequences of subunits, structure, and functional mechanisms, suggesting that cyanobacterial ATP synthase is probably the evolutionary precursor to chloroplast ATP synthase. In this review, we explore the precise synthesis and assembly of ATP synthase subunits to address the uneven stoichiometry within the complex during transcription, translation, and assembly processes. We also compare the regulatory strategies governing ATP synthase activity to meet varying energy demands in cyanobacteria and chloroplasts amid fluctuating natural environments. Furthermore, we delve into the role of ATP synthase in stress tolerance and photosynthetic carbon fixation efficiency in oxygenic photosynthetic organisms (OPsOs), along with the current researches on modifying ATP synthase to enhance carbon fixation efficiency under stress conditions. This review aims to offer theoretical insights and serve as a reference for understanding the functional mechanisms of ATP synthase, sparking innovative ideas for enhancing photosynthetic carbon fixation efficiency by utilizing ATP synthase as an effective module in OPsOs.

9.
Sheng Wu Gong Cheng Xue Bao ; 40(6): 1752-1775, 2024 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-38914490

RESUMO

Thermophilic cyanobacteria are prokaryotic organisms that possess exceptional heat-resistant characteristics. This group serves as an excellent model for investigating the heat tolerance of higher photosynthetic organisms, including higher plants, some protists (such as algae and euglena), and bacteria. Analyzing the mechanisms of high-temperature adaptation in thermophilic cyanobacteria can enhance our understanding of how photosynthetic organisms and microorganisms tolerate high temperatures at the molecular level. Additionally, these thermotolerant cyanobacteria have the potential to contribute to breeding heat-tolerant plants and developing microbial cell factories. This review summarizes current research on thermophilic cyanobacteria, focusing on their ecology, morphology, omics studies, and mechanisms of high-temperature tolerance. It offers insight into the potential biotechnological applications of thermophilic cyanobacteria and highlights future research opportunities. Specifically, attention is given to the photosynthetic physiology and metabolism of cyanobacteria, and the molecular basis of heat-tolerance mechanisms in thermophilic cyanobacteria is explored.


Assuntos
Adaptação Fisiológica , Biotecnologia , Cianobactérias , Temperatura Alta , Fotossíntese , Cianobactérias/fisiologia , Cianobactérias/metabolismo , Termotolerância
10.
Chem Sci ; 15(12): 4590-4601, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38516086

RESUMO

π-Conjugated macrocycles have been highly attractive due to their challenging synthesis, fascinating aesthetic structure and unique physical and chemical properties. Although some progress has been made in synthesis, the study of π-macrocycles with different structural characteristics and supramolecular interactions still faces major challenges. In this paper, two new single-bond linked macrocycles (MS-4T/MS-6T) were reported, and the corresponding vinyl-bridged heterocycloarenes (MF-4T/MF-6T) were synthesized by the periphery fusion strategy. Further studies have indicated that the structure of these four macrocycles is determined by both size and curvature, showing unique variations from nearly planar to bowl and then to saddle. Interestingly, the nearly planar MS-4T with a small size and the rigid saddle-shaped MF-6T show no obvious response to fullerenes C60 or C70, while the bowl-shaped MS-6T and MF-4T demonstrate a strong binding affinity towards fullerenes C60 and C70. What's more, two kinds of co-crystals with capsule-like configurations, MS-6T@C60 and MS-6T@C70, have been successfully obtained, among which the former shows a loose columnar arrangement while the latter displays a unique three-dimensional honeycomb arrangement that is extremely rare in supramolecular complexes. This work systematically studies the π-conjugated macrocycles and provides a new idea for the development of novel host-guest systems and further multifunctional applications.

11.
Org Lett ; 26(23): 5010-5015, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38819192

RESUMO

Two fully fused acceptor-donor-acceptor (A-D-A) architecture conjugated derivatives (NPF and NCF) comprising an electron-withdrawing naphthalimide (NMI) and two different electron-donating cores, phenanthrene and carbazole, respectively, were conveniently synthesized by bismuth(III)-catalyzed selective cyclization of vinyl ethers. Compared with their corresponding single bond-linked A-D-A molecules NPS and NCS, both having a moderately twisted aromatic configuration, the ring fusion strategy leads to fully coplanar conjugated skeletons and greatly changes the electronic structures, photophysical properties, self-assembling behaviors, and molecular packing motifs. In particular, the naphthalimide/carbazole derivative NCF exhibits intriguing 2D brickwork packing and significantly enhanced self-assembling properties.

12.
Small Methods ; 8(8): e2301415, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38507722

RESUMO

In recent times, newly unveiled 2D materials exhibiting exceptional characteristics, such as MBenes and MXenes, have gained widespread application across diverse domains, encompassing electronic devices, catalysis, energy storage, sensors, and various others. Nonetheless, numerous technical bottlenecks persist in the development of high-performance, structurally flexible, and adjustable electronic device materials. Research investigations have demonstrated that 2D van der Waals superlattices (vdW SLs) structures comprising materials exhibit exceptional electrical, mechanical, and optical properties. In this work, the advantages of both materials are combined and compose the vdW SLs structure of MBenes and MXenes, thus obtaining materials with excellent electronic properties. Furthermore, it integrates machine learning (ML) with first-principles methods to forecast the electrical properties of MBene/MXene superlattice materials. Initially, various configurations of MBene/MXene superlattice materials are explored, revealing that distinct stacking methods exert significant influence on the electronic structure of MBene/MXene materials. Specifically, the BABA-type stacking of CrB (layer A) and Co2CO2 MXene (layer B) is most stable configureation. Subsequently, multiple descriptors of the structure are constructed to predict the density of states  of vdW SLs through the employment of ML techniques. The best model achieves a mean absolute error (MAE) as low as 0.147 eV.

13.
Bioresour Technol ; 406: 131062, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38964514

RESUMO

Acquiring lipid-producing strains of Saccharomyces cerevisiae is necessary for producing high-value palmitoleic acid. This study sought to generate oleaginous S. cerevisiae mutants through a combination of zeocin mutagenesis and fluorescence-activated cell sorting, and then to identify key mutations responsible for enhanced lipid accumulation by multi-omics sequencing. Following three consecutive rounds of mutagenesis and sorting, a mutant, MU310, with the lipid content of 44%, was successfully obtained. Transcriptome and targeted metabolome analyses revealed that a coordinated response involving fatty acid precursor biosynthesis, nitrogen metabolism, pentose phosphate pathway, ethanol conversion, amino acid metabolism and fatty acid ß-oxidation was crucial for promoting lipid accumulation. The carbon fluxes of acetyl-CoA and NADPH in lipid biosynthesis were boosted in these pathways. Certain transcriptional regulators may also play significant roles in modulating lipid biosynthesis. Results of this study provide high-quality resource for palmitoleic acid production and deepen the understanding of lipid synthesis in yeast.


Assuntos
Lipídeos , Mutagênese , Saccharomyces cerevisiae , Ácidos Graxos/metabolismo , Ácidos Graxos Monoinsaturados , Citometria de Fluxo , Metabolismo dos Lipídeos , Lipídeos/biossíntese , Metaboloma , Multiômica , Mutação , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/genética , Transcriptoma/genética
14.
Bioresour Technol ; : 131295, 2024 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-39155017

RESUMO

The cultivation of microalgae is significantly influenced by light intensity and utilization efficiency. This study developed a modified Cornet (M-Cornet) model to assess the distribution of light intensity and flux in microalgae cultivation systems. Algal biofilm cultivation represents a more concentrated approach of algal suspension cultivation. Both follow the M-Cornet model and exhibit the same growth rates when cultured under identical conditions. Algal pigments and morphologies greatly impact the light absorption and scattering, resulting in light attenuation in intensity, penetration distance and light flux distribution. Algae varieties exhibit diverse light flux characteristics. 37% - 90% of the incident light is absorbed, of which, 80% to 90% is dissipated as heat. 10% to 63% of the incident light is scattered off the photobioreactor. The overall light utilization efficiency ranges 6% to 13%. The light footprint using the M-Cornet model offers valuable insights for photobioreactors designing and cultivation operating.

15.
Enzyme Microb Technol ; 175: 110406, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38330706

RESUMO

The chiral amine (R)-2-(1-aminoethyl)-4-fluorophenol has attracted increasing attentions in recent years in the field of pharmaceuticals because of its important use as a building block in the synthesis of novel anti-tumor drugs targeting tropomyosin receptor kinases. In the present study, a ω-transaminase (ωTA) library consisting of 21 (R)-enantioselective enzymes was constructed and screened for the asymmetric biosynthesis of (R)-2-(1-aminoethyl)-4-fluorophenol from its prochiral ketone. Using (R)-α-methylbenzylamine, D-alanine, or isopropylamine as amino donor, 18 ωTAs were identified with target activity and the enzyme AbTA, which was originally identified from Arthrobacter sp. KNK168, was found to be a potent candidate. The E. coli whole cells expressing AbTA could be used as catalysts. The optimal temperature and pH for the activity were 35-40 °C and pH8.0, respectively. Simple alcohols (such as ethanol, isopropanol, and methanol) and dimethyl sulfoxide were shown to be good cosolvents. High activities were detected when using ethanol and dimethyl sulfoxide at the concentrations of 5-20%. In the scaled-up reaction of 1-liter containing 13 mM ketone substrate, about 50% conversion was achieved in 24 h. 6.4 mM (R)-2-(1-aminoethyl)-4-fluorophenol was generated. After a simple and efficient process of product isolation and purification (with 98.8% recovery), 0.986 g yellowish powder of the product (R)-2-(1-aminoethyl)-4-fluorophenol with high (R)-enantiopurity (up to 100% enantiomeric excess) was obtained. This study established an overall process for the biosynthesis of the high value pharmaceutical chiral amine (R)-2-(1-aminoethyl)-4-fluorophenol by ωTA. Its applicable potential was exemplified by gram-scale production.


Assuntos
Antineoplásicos , Fenóis , Transaminases , Dimetil Sulfóxido , Escherichia coli , Cetonas , Antineoplásicos/farmacologia , Catálise , Etanol
16.
ACS Appl Mater Interfaces ; 16(30): 40111-40122, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39031063

RESUMO

The conceptualization and deployment of electrode materials for rechargeable sodium-ion batteries are key concerns for next-generation energy storage systems. In this contribution, the configuration stability of single-layer GeSiBi2 is systematically discussed based on first-principles calculations, and its potential as an anode material is further investigated. It is demonstrated that the phonon spectrum confirms the dynamic stability and the adsorption energy identifies a strong interaction between Na atoms and the substrate material. The electronic bands indicative of inherent metallicity contribute to the enhancement of electronic conductivity after Na adsorption. The multilayer adsorption of Na provides a theoretical capacity of 361.7 mAh/g, which is comparable to that of other representative two-dimensional anode materials. Moreover, the low diffusion barriers of 0.19 and 0.15 eV further guarantee the fast diffusion kinetics. These contributions signal that GeSiBi2 can be a compatible candidate for sodium-ion batteries anodes.

17.
J Imaging Inform Med ; 37(1): 374-385, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38343259

RESUMO

Fully supervised medical image segmentation methods use pixel-level labels to achieve good results, but obtaining such large-scale, high-quality labels is cumbersome and time consuming. This study aimed to develop a weakly supervised model that only used image-level labels to achieve automatic segmentation of four types of uterine lesions and three types of normal tissues on magnetic resonance images. The MRI data of the patients were retrospectively collected from the database of our institution, and the T2-weighted sequence images were selected and only image-level annotations were made. The proposed two-stage model can be divided into four sequential parts: the pixel correlation module, the class re-activation map module, the inter-pixel relation network module, and the Deeplab v3 + module. The dice similarity coefficient (DSC), the Hausdorff distance (HD), and the average symmetric surface distance (ASSD) were employed to evaluate the performance of the model. The original dataset consisted of 85,730 images from 316 patients with four different types of lesions (i.e., endometrial cancer, uterine leiomyoma, endometrial polyps, and atypical hyperplasia of endometrium). A total number of 196, 57, and 63 patients were randomly selected for model training, validation, and testing. After being trained from scratch, the proposed model showed a good segmentation performance with an average DSC of 83.5%, HD of 29.3 mm, and ASSD of 8.83 mm, respectively. As far as the weakly supervised methods using only image-level labels are concerned, the performance of the proposed model is equivalent to the state-of-the-art weakly supervised methods.

18.
Sci Total Environ ; 922: 171200, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38408662

RESUMO

The CO2 and 14CO2 levels in air samples from the northern foot of the Qinling Mountains (Xi'an, China) were determined. In 2021, a hexacopter unmanned aerial vehicle sampled air at different heights, from near-ground to 2000 m. The objectives of this study were to determine vertical characteristics of CO2 and 14CO2, the sources of different-height CO2, and the influence of air mass transport. The CO2 concentrations mainly exhibited a slight decreasing trend with increasing height during summer observations, which was in contrast to the increasing trend that was followed by a subsequent gradual decreasing trend during early winter observations, with peak CO2 levels (443.4 ± 0.4-475.7 ± 0.5 ppm) at 100-500 m. The variation in vertical concentrations from 20 to 1000 m in early winter observations (21.6 ± 19.3 ppm) was greater than that in summer observations (14.6 ± 14.3 ppm), and the maximum vertical variation from 20 to ∼2000 m reached 61.1 ppm. Combining Δ14C and δ13C vertical measurements, the results showed that fossil fuel CO2 (CO2ff, 56.1 ± 15.2 %), which mainly come from coal combustion (81.2 ± 3.4 %), was the main contributor to CO2 levels in excess of the background level (CO2ex) during early winter observations. In contrast, biological CO2 (CO2bio) dominated CO2ex in summer observations. The vertical distributions of CO2ff in early winter observations and CO2bio in summer observations were consistent with those of CO2 during early winter and summer observations, respectively. The strong correlation between winter CO2bio and ΔCO (r = 0.81, p < 0.01) indicated that biomass burning was the main contributor to CO2bio during early winter observations. Approximately half of the air masses originated from the Guanzhong Basin during observations. The results provide insights into the vertical distribution of different-sources of atmospheric CO2 in scientific support of formulating carbon emission-reduction strategies.

19.
Sci Total Environ ; 920: 170682, 2024 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-38325447

RESUMO

A two-year (March 2021 to February 2023) continuous atmospheric CO2 and a one-year regular atmospheric 14CO2 measurement records were measured at the northern foot of the Qinling Mountains in Xi'an, China, aiming to study the temporal characteristics of atmospheric CO2 and the contributions from the sources of fossil fuel CO2 (CO2ff) and biological CO2 (CO2bio) fluxes. The two-year mean CO2 mole fraction was 442.2 ± 16.3 ppm, with a yearly increase of 4.7 ppm (i.e., 1.1 %) during the two-year observations. Seasonal CO2 mole fractions were the highest in winter (452.1 ± 17.7 ppm) and the lowest in summer (433.5 ± 13.3 ppm), with the monthly CO2 levels peaking in January and troughing in June. Diurnal CO2 levels peaked at dawn (05:00-07:00) in spring, summer and autumn, and at 10:00 in winter. 14C analysis revealed that the excess CO2 (CO2ex, atmospheric CO2 minus background CO2) at this site was mainly from CO2ff emissions (67.0 ± 26.8 %), and CO2ff mole fractions were the highest in winter (20.6 ± 17.7 ppm). Local CO enhancement above the background mole fraction (ΔCO) was significantly (r = 0.74, p < 0.05) positively correlated with CO2ff in a one-year measurement, and ΔCO:CO2ff showed a ratio of 23 ± 6 ppb/ppm during summer and winter sampling days, much lower than previous measurements and suggesting an improvement in combustion efficiency over the last decade. CO2bio mole fractions also peaked in winter (14.2 ± 9.6 ppm), apparently due to biomass combustion and the lower and more stable wintertime atmospheric boundary layer. The negative CO2bio values in summer indicated that terrestrial vegetation of the Qinling Mountains had the potential to uptake atmospheric CO2 during the corresponding sampling days. This site is most sensitive to local emissions from Xi'an and to short distance transportation from the southern Qinling Mountains through the valleys.

20.
Medicine (Baltimore) ; 103(25): e38081, 2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-38905385

RESUMO

A multicenter retrospective analysis of conventionally collected data. To identify the potential causes of hypoproteinemia after traumatic spinal cord injury (TSCI) and provide a diagnostic model for predicting an individual likelihood of developing hypoproteinemia. Hypoproteinemia is a complication of spinal cord injury (SCI), an independent risk factor for respiratory failure in elderly patients with SCI, and a predictor of outcomes in patients with cervical SCI. Few nomogram-based studies have used clinical indicators to predict the likelihood of hypoproteinemia following TSCI. This multicenter retrospective clinical analysis included patients with TSCI admitted to the First Affiliated Hospital of Guangxi Medical University, Wuzhou GongRen Hospital, and Dahua Yao Autonomous County People Hospital between 2016 and 2020. The data of patients from the First Affiliated Hospital of Guangxi Medical University were used as the training set, and those from the other 2 hospitals were used as the validation set. All patient histories, diagnostic procedures, and imaging findings were recorded. To predict whether patients with TSCI may develop hypoproteinemia, a least absolute shrinkage and selection operator regression analysis was conducted to create a nomogram. The model was validated by analyzing the consequences using decision curve analysis, calibration curves, the C-index, and receiver operating characteristic curves. After excluding patients with missing data, 534 patients were included in this study. Male/female sex, age ≥ 60 years, cervical SCI, pneumonia, pleural effusion, urinary tract infection (UTI), hyponatremia, fever, hypotension, and tracheostomy were identified as independent risk factors of hypoalbuminemia. A simple and easy-to-replicate clinical prediction nomogram was constructed using these factors. The area under the curve was 0.728 in the training set and 0.881 in the validation set. The predictive power of the nomogram was satisfactory. Hypoalbuminemia after TSCI may be predicted using the risk factors of male/female sex, age ≥ 60 years, cervical SCI, pneumonia, pleural effusion, UTI, hyponatremia, fever, hypotension, and tracheostomy.


Assuntos
Hipoproteinemia , Nomogramas , Traumatismos da Medula Espinal , Humanos , Feminino , Masculino , Traumatismos da Medula Espinal/complicações , Estudos Retrospectivos , Pessoa de Meia-Idade , Idoso , Adulto , Hipoproteinemia/etiologia , Fatores de Risco , Curva ROC , China/epidemiologia
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