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1.
Phys Chem Chem Phys ; 25(5): 3607-3616, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36254862

RESUMO

Space confined reactions have emerged as a viable strategy for achieving important and fascinating properties in functional materials. Various scaffolds have been reported so far for confinement and it gives rise to the phenomenon of nanoconfinement, where the energetics and kinetics of catalytic reactions can be modulated upon confining the catalysts in a particular site. Although various systems have been reported so far for confinement, emphasis has been placed on the concept of space confinement, and the changes in the confined space itself are neglected. Strikingly, this critical issue would be touched on and revealed by supercritical CO2 (SC CO2) that is used in confined geometries. Herein, we define the structural changes of confined spaces induced by SC CO2 as an anti-nanoconfinement effect, which can bring about a series of variations together with electronic band and structural transformation. Moreover, progress in the design and applications of the anti-nanoconfinement effect is traced, and there is a discussion of emerging issues that have yet to be explored to achieve a future direction to develop more novel two-dimensional (2D) structures.

2.
Molecules ; 28(3)2023 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-36770703

RESUMO

The characteristics of active sites on the surface of albite were theoretically analyzed by density functional theory, and the activation of the C-H bond of methane using an albite catalyst and the reaction mechanism of preparing C2 hydrocarbons by nonoxidative coupling were studied. There are two frustrated Lewis pairs (FLPs) on the (001) and (010) surfaces of albite; they can dissociate H2 under mild conditions and show high activity for the activation of methane C-H bonds. CH4 molecules can undergo direct dissociative adsorption on the (010) surface, whereas a 50.07 kJ/mol activation barrier is needed on the (001) surface. The prepared albite catalyst has a double combination function of the (001) and (010) surfaces; these surfaces produce a spillover phenomenon in the process of CH4 activation reactions, where CH3 overflows from the (001) surface with CH3 adsorbed on the (010) surface to achieve nonoxidative high efficiently C-C coupling with an activation energy of 18.51 kJ/mol. At the same time, this spillover phenomenon inhibits deep dehydrogenation, which is conducive to the selectivity of the C2 hydrocarbons. The experimental results confirm that the selectivity of the C2 hydrocarbons is maintained above 99% in the temperature range of 873 K to 1173 K.

3.
J Clin Rheumatol ; 29(5): e92-e99, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37011178

RESUMO

OBJECTIVE: Botulinum toxin (Btx) therapy has emerged as a potential treatment for patients with Raynaud phenomenon (RP) in recent years. This study aimed to investigate the efficacy and safety of Btx treatment for RP. METHODS: Databases of PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials were searched from their inception up to August 2022. Studies that reported Btx use for the treatment of RP were included. A meta-analysis was conducted for the Shortened version of the Disabilities of the Arm, Shoulder, and Hand (Quick DASH) score and visual analog scale pain score using a random-effects model. RESULTS: Thirteen full-text studies were included. The pooled standard mean changes for the visual analog scale pain score and QuickDASH score were -3.82 (95% confidence interval, -6.62 to -1.02) and 0.83 (95% confidence interval, -1.47 to -0.19), respectively. The 2 most common complications were injection site pain and intrinsic hand weakness. CONCLUSIONS: The effect of Btx treatment on RP is promising based on current evidence. Nevertheless, more studies and randomized clinical trials with larger sample sizes are needed to confirm the current results.


Assuntos
Toxinas Botulínicas Tipo A , Fármacos Neuromusculares , Doença de Raynaud , Humanos , Toxinas Botulínicas Tipo A/efeitos adversos , Fármacos Neuromusculares/efeitos adversos , Dor , Mãos , Doença de Raynaud/diagnóstico , Doença de Raynaud/tratamento farmacológico
4.
Chemistry ; 28(61): e202201811, 2022 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-35932164

RESUMO

The development of an efficient strategy for fabricating two-dimensional metal-organic framework (MOF) nanosheets with high yield and high stability is desirable. Herein, we demonstrate for the first time that large, single-layer 2D nickel-benzene dicarboxylate (Ni-BDC) MOF nanosheets can be fabricated with the assistance of supercritical (SC) CO2 in a pure aqueous system. Detailed experimental evidence reveals that the SC CO2 molecule can exchange with the lattice-coordinated H2 O molecules, side-on coordinate with the metal Ni1 sites on the Ni-BDC surface, and finally break the interlayer hydrogen bond to exfoliate the bulk Ni-BDC into a 2D MOF. More importantly, a thin SC CO2 layer building up at the water-Ni-BDC interfaces can transform the pristine hydrophilic interface into a super-hydrophobic one. This super-hydrophobic layer at the water-MOF interface can effectively prevent dissociation, thus promoting the stability of Ni-BDC in aqueous system.

5.
Chemphyschem ; 23(22): e202200342, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-35871763

RESUMO

Few studies focus on the plastic deformations of inorganic semiconductors because they are usually brittle and do not deform easily. Here, a peculiar internal shear stress originated from the entropy deletion of CO2 in the tunnels of non-van der Waals VO2 crystal, is employed to introduce hierarchical plastic deformations, including dislocations, point vacancies, twins, and amorphous bands. The strength of such stress field increases by more than three orders of magnitude compared to that of external experimental CO2 pressure. We further demonstrate that 2D amorphous structures can be obtained by the synergetic effect of hierarchical deformations in 3D crystal.

6.
Phys Chem Chem Phys ; 24(44): 27515-27523, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36345607

RESUMO

Impregnating noble metals in metal-organic frameworks (MOFs) for obtaining effective catalysts for the photocatalytic process is of great significance but remains very challenging. Herein, for the first time, atomically dispersed Pt atoms were successfully impregated inside the MOF UiO-66 with the assistance of supercritical carbon dioxide (SC CO2). Our study demonstrated that the SC CO2-directed strategy makes Pt undergo a stable encapsulation inside UiO-66, realizing a stage for the rapid transfer of photogenerated electrons between the components of the composite, hence dramatically increasing the catalytic effect. Further, theoretical calculations demonstrated the experimental characterization of the unique structure. Moreover, the as-prepared hybrid structure of Pt@UiO-66 composites presented an extremely high photocatalytic efficiency for hydrogen evolution under visible-light irradiation. An unusual H2 production rate of 3871.4 µmol h-1 g-1 could be achieved by Pt@UiO-66 under visible-light irradiation. This was nearly 50 times higher than the H2-evolution rate achieved by pure UiO-66 under the full spectrum.

7.
J Environ Manage ; 305: 114402, 2022 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-34998060

RESUMO

Recent studies have increasingly focused on China's CO2 emission intensity (CEI). However, specific or sufficient guidance is needed with regard to China's complex regional differences and the underlying relations between drivers and CEI. Herein, we develop a novel evolution tree based on the extended Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model to spatially visualize and quantify regional development patterns and the impact of determinants on CEI in China. The results showed that China's CEI spatially decreased from the northwest inland to the southeast coast and showed an overall annual decrease. Different regions with various regional development patterns have varying impact mechanisms on local CEI. In the highly developed region, affluence and industrial structure had the greatest effect, with an elasticity coefficient of -0.63, and 0.63, respectively. In the upper-middle developed, lower-middle developed, and developing regions, the energy structure exerted the greatest effect on local CEI with elasticity coefficients of 0.98%, 2.06%, and 0.95%, respectively. In the underdeveloped region, population had the greatest promotion effect with an impact of 1.42; however, affluence exerts a pronounced inhibitory effect with an impact of -0.63. Factors affecting China's CEI have regionally varied effects. Affluence had a significant inhibitory effect on CEI in all five regions, especially in the underdeveloped region; population had a negative effect in the relatively developed regions and a positive effect in the less developed regions. Other factors exerted a positive effect in all five regions, but their significance varied regionally. These results can help policymakers adopt effective regional energy conservation and emission reduction measures.


Assuntos
Desenvolvimento Econômico , Gases de Efeito Estufa , Dióxido de Carbono/análise , China , Gases de Efeito Estufa/análise , Indústrias , Tecnologia
8.
Angew Chem Int Ed Engl ; 59(8): 3322-3328, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31850648

RESUMO

In two-dimensional (2D) amorphous nanosheets, the electron-phonon coupling triggered by localization of the electronic state as well as multiple-scattering feature make it exhibit excellent performance in optical science. VS2 nanosheets, especially single-layer nanosheets with controllable electronic structure and intrinsic optical properties, have rarely been reported owing to the limited preparation methods. Now, a controllable and feasible switching method is used to fabricate 2D amorphous VS2 and partial crystallized 2D VO2 (D) nanosheets by altering the pressure and temperature of supercritical CO2 precisely. Thanks to the strong carrier localization and the quantum confinement, the unique 2D amorphous structures exhibit full band absorption, strong photoluminescence, and outstanding photothermal conversion efficiency.

9.
J Am Chem Soc ; 138(48): 15751-15757, 2016 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-27934025

RESUMO

Spin-crossover (SCO) is generally regarded as a spectacular molecular magnetism in 3d4-3d7 metal complexes and holds great promise for various applications such as memory, displays, and sensors. In particular, SCO materials can be multifunctional when a classical light- or temperature-induced SCO occurs along with other cooperative structural and/or electrical transport alterations. However, such a cooperative SCO has rarely been observed in condensed matter under hydrostatic pressure (an alternative external stimulus to light or temperature), probably due to the lack of synergy between metal neighbors under compression. Here, we report the observation of a pressure-driven, cooperative SCO in the two-dimensional (2D) honeycomb antiferromagnets MnPS3 and MnPSe3 at room temperature. Applying pressure to this confined 2D system leads to a dramatic magnetic moment collapse of Mn2+ (d5) from S = 5/2 to S = 1/2. Significantly, a number of collective phenomena were observed along with the SCO, including a large lattice collapse (∼20% in volume), the formation of metallic bonding, and a semiconductor-to-metal transition. Experimental evidence shows that all of these events occur in the honeycomb lattice, indicating a strongly cooperative mechanism that facilitates the occurrence of the abrupt pressure-driven SCO. We believe that the observation of this cooperative pressure-driven SCO in a 2D system can provide a rare model for theoretical investigations and lead to the discovery of more pressure-responsive multifunctional materials.

10.
Chem Sci ; 15(21): 8106-8111, 2024 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-38817588

RESUMO

Efficient electron-transporting materials (ETMs) are critical to achieving excellent performance of organic light-emitting diodes (OLEDs), yet developing such materials remains a major long-term challenge, particularly ETMs with high electron mobilities (µeles). Herein, we report a short conjugated ETM molecule (PICN) with a dipolar phenanthroimidazole group, which exhibits an electron mobility of up to 1.52 × 10-4 cm2 (V-1 s-1). The origin of this high µele is long-ranged, regulated special cage-like interactions with C-H⋯N radii, which are also favorable for the excellent efficiency stability and operational stability in OLEDs. It is worth noting that the green phosphorescent OLED operation half-lifetimes can reach up to 630 h under unencapsulation, which is 20 times longer than that based on the commonly used commercial ETM TPBi.

11.
Chem Sci ; 15(15): 5589-5595, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38638218

RESUMO

Organic deep-red (DR) and near-infrared (NIR) emitters with high photoluminescence quantum yield (PLQY) are rare due to the strong non-radiative (knr) decay. Here, we report two DR/NIR emitters with high PLQY, TPANZPyPI and TPANZ3PI. Interestingly, the TPANZPyPI film exhibits 46.5% PLQY at 699 nm. Theoretical calculations indicate that TPANZPyPI can achieve this high PLQY in the near-infrared emission region due to its small S1 to S0 internal conversion (IC) rate. Meanwhile, research has found that, compared to TPANZ3PI, TPANZPyPI with a more rigid structure can effectively suppress the T2 to T1 IC process, which is conducive to higher exciton utilization efficiency (EUE). TPANZPyPI's non-doped OLED shows NIR emission with 4.6% @ 684 nm maximum external quantum efficiency (EQEmax). Its doped OLEDs radiate DR with an EQEmax of 6.9% @ 666 nm. These EQEs are among the highest values for hybridized local charge transfer state materials emitting more than 640 nm. This work demonstrates for the first time, based on a combination of theory and experiment, that increasing the molecular rigidity can inhibit the excited state IC process in addition to the S1 to S0 IC, realizing efficient electroluminescence.

12.
Artigo em Inglês | MEDLINE | ID: mdl-38643450

RESUMO

Latuda® is a novel antipsychotic drug for schizophrenia and bipolar depression. A bioequivalence trial was performed to investigate the bioequivalence of Latuda® and its generic drug lurasidone. Two independent trials were carried out, each involving 28 subjects. In the fasting trial, subjects were randomly assigned to two groups (1:1 ratio), receiving either 40 mg of generic lurasidone or Latuda®. After a 7-day washout period, subjects entered the second period with a crossover administration of 40 mg of generic lurasidone or Latuda®. The postprandial study design was similar to that of the fasting study. In the fasting study, the pharmacokinetic (PK) parameter values of generic lurasidone and Latuda® were as follows: the Cmax was 28.84 ± 19.34 ng/ml and 28.22 ± 21.19 ng/ml, respectively; the AUC0-t was 121.39 ± 58.47 h*ng/ml and 118.35 ± 52.24 h*ng/ml, respectively; and the AUC0-∞ was 129.63 ± 63.26 h*ng/ml and 126.59 ± 57.99 h*ng/ml, respectively. The primary pharmacokinetic parameter, Cmax, was assessed for equivalence using reference-scaled average bioequivalence (RSABE), while other parameters (AUC0-t, AUC0-∞) were evaluated using average bioequivalence (ABE). The results indicate that both Cmax and AUC meet the equivalence criteria. In the postprandial study, the PK values of generic lurasidone and Latuda® were as follows: the Cmax was 74.89 ± 32.06 ng/ml and 83.51 ± 33.52 ng/ml, respectively; the AUC0-t was 274.77 ± 103.05 h*ng/ml and 289.26 ± 95.25 h*ng/ml, respectively; and the AUC0-∞ was 302.44 ± 121.60 h*ng/ml and 316.32 ± 109.04 h*ng/ml, respectively. The primary pharmacokinetic parameters (Cmax, AUC0-t, AUC0-∞) were assessed for equivalence using ABE, and both met the equivalence criteria. In the study, lurasidone and Latuda® both exhibited acceptable safety and tolerability. The results displayed that lurasidone and Latuda® were bioequivalent and safe in healthy Chinese participants. Clinical Trial Registry: This trial is registered at chinadrugtrials.org.cn (no.: CTR20191717, date: 2019.08.29).

13.
ChemistryOpen ; 12(10): e202300058, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37803405

RESUMO

The characteristics of frustrated Lewis pairs (FLPs) on albite surfaces were analyzed with density functional theory, and the reaction mechanism for H2 activation by the FLPs was studied. The results show that albite is an ideal substrate material with FLPs, and its (001) and (010) surfaces have the typical characteristics of FLPs. In the case of H2 activation, the interaction between the HOMO of H2 and the SOMO of the Lewis base and the electron acceptance characteristics of the Lewis acid are the key factors. In fact, the activation energy of H2 is the required activation energy from the ground state to the excited state, and once the excited state is produced, the dissociative adsorption of H2 will occur directly. This study provides a new ideas and a reference for research on the construction of novel solid FLPs catalysts using ultramicro channel materials.

14.
Orthop Surg ; 15(2): 525-533, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36573278

RESUMO

OBJECTIVES: Red blood cell distribution width (RDW) with prognosis in various infectious diseases. For fractured patients admitted to the intensive care units (ICU), an accurate and fast appraisal is essential. To investigate the association between RDW and prognosis in fractured patients admitted to the ICU utilizing the MIMIC-III database. METHODS: A retrospective cohort from the MIMIC III database from 2001 and 2012 was constructed. RDW and other information were collected with in-hospital mortality as the primary outcome and 90-day mortality and hospital and intensive care unit (ICU) length of stay (LOS) as secondary outcomes. Univariate and multivariate logistic regression models with propensity score inverse probability of treatment weighting (IPTW) were used to investigate the prognostic value of RDW. A nomogram was built with significant prognostic factors to predict in-hospital mortality, and the performance of the nomogram was evaluated and compared with other severity assessment scores. Subgroup analysis was also conducted. RESULTS: A total of 2721 fracture patients admitted to the ICU were identified. After IPTW, the group with higher RDW was significantly associated with elevated in-hospital mortality (odds ratio [OR]: 1.68, 95% confidence interval [CI]: 1.19-2.37), 90-day mortality (OR: 1.39, 95% CI: 1.04-1.86), prolonged hospital LOS (OR: 1.25, 95% CI: 1.03-1.50), and ICU LOS significantly (OR: 1.26, 95% CI: 1.05-1.53) in the multivariate logistics model. The nomogram showed optimal discriminative ability and predictive accuracy with an area under the receiver operating characteristic curve of 0.77. CONCLUSION: RDW independently predicted in-hospital mortality, 90-day mortality, and hospital and ICU LOS in fractured patients admitted to ICU. The nomogram including RDW could also be a promising tool with potential clinical benefits.


Assuntos
Hospitalização , Unidades de Terapia Intensiva , Humanos , Estudos Retrospectivos , Prognóstico , Curva ROC , Eritrócitos
15.
Nat Food ; 4(6): 483-495, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37322300

RESUMO

Greenhouse gas (GHG) emissions related to food consumption complement production-based or territorial accounts by capturing carbon leaked through trade. Here we evaluate global consumption-based food emissions between 2000 and 2019 and underlying drivers using a physical trade flow approach and structural decomposition analysis. In 2019, emissions throughout global food supply chains reached 30 ±9% of anthropogenic GHG emissions, largely triggered by beef and dairy consumption in rapidly developing countries-while per capita emissions in developed countries with a high percentage of animal-based food declined. Emissions outsourced through international food trade dominated by beef and oil crops increased by ~1 Gt CO2 equivalent, mainly driven by increased imports by developing countries. Population growth and per capita demand increase were key drivers to the global emissions increase (+30% and +19%, respectively) while decreasing emissions intensity from land-use activities was the major factor to offset emissions growth (-39%). Climate change mitigation may depend on incentivizing consumer and producer choices to reduce emissions-intensive food products.


Assuntos
Gases de Efeito Estufa , Animais , Bovinos , Efeito Estufa , Ração Animal , Produtos Agrícolas
16.
Expert Opin Investig Drugs ; 32(3): 263-270, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36757390

RESUMO

BACKGROUND: Dasatinib (Sprycel®) is a tyrosine kinase inhibitor for treating chronic myeloid leukemia and Philadelphia chromosome-positive acute lymphoblastic leukemia. RESEARCH DESIGN & METHODS: We designed a clinical study to demonstrate that the dasatinib tablet (YiNiShu®) (Chia Tai Tianqing Pharmaceutical Group Co., Ltd) and Dasatinib (Bristol Myers Squibb) were bioequivalent under fasting and fed conditions. The whole study was structured into the fasting trial and the postprandial trial. Each period, subjects were given 50 mg dasatinib or its generic. The RSABE (reference scale average bioequivalence) and ABE (average bioequivalence) methods were employed to assess bioequivalence by pharmacokinetics (PK) parameters for a highly variable drug. RESULTS: 32 and 24 eligible volunteers were enrolled in the fasting and postprandial trials, respectively. In the fasting trial, the RSABE method was performed, and point estimates of Cmax, AUC0-t, and AUC0-∞ met the bioequivalence criteria. In the postprandial trial, the ABE method was performed, and the 90% CI of the geometric mean ratio (GMR) for PK parameters met the requirements of bioequivalence standards. CONCLUSION: The results proved that the PK parameters of the two drugs were similar and bioequivalent, indicating that both drugs had a good safety profile. CLINICAL TRIAL REGISTRATION: This trial was registered in ClinicalTrials.gov (Number: NCT05640804) and Drug Clinical Trial Registration and Information Disclosure Platform (Number: CTR20181708).


Assuntos
Dasatinibe , Medicamentos Genéricos , População do Leste Asiático , Humanos , Área Sob a Curva , Disponibilidade Biológica , Dasatinibe/farmacocinética , Medicamentos Genéricos/farmacocinética , Jejum , Equivalência Terapêutica
17.
Diagnostics (Basel) ; 13(20)2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37892038

RESUMO

The study aims to develop a decision pathway based on HEAR score and 0 h high-sensitivity cardiac troponin T (hs-cTnT) to safely avoid a second troponin test for suspected non-ST elevation myocardial infarction (NSTEMI) in emergency departments. A HEAR score consists of history, electrocardiogram, age, and risk factors. A HEAR pathway is established using a Bayesian approach based on a predefined safety threshold of NSTEMI prevalence in the rule-out group. In total, 7131 patients were retrospectively enrolled, 582 (8.2%) with index visit NSTEMI and 940 (13.2%) with 180-day major adverse cardiovascular events (MACE). For patients with a low-risk HEAR score (0 to 2) and low 0 h hs-cTnT (<14 ng/L), the HEAR pathway recommends early discharge without further testing. After the HEAR pathway had been applied to rule out NSTEMI, the negative predictive value of index visit NSTEMI was 100.0% (95% CI, 99.8% to 100.0%) and false-negative rate of 180-day MACE was 0.40% (95% CI, 0.18% to 0.87%). Compared with the 0 h hs-cTnT < limit of detection (LoD) strategy (<5 ng/L), the HEAR pathway could correctly reclassify 1298 patients without MACE as low risk and lead to a 18.2% decrease (95% CI, 17.4-19.1%) in the need for a second troponin test. The HEAR pathway may lead to a substantial and safe reduction in repeated troponin test for emergency department patients with suspected NSTEMI.

18.
Expert Rev Clin Pharmacol ; 16(4): 363-370, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36883362

RESUMO

BACKGROUND: Glucagon-like peptide-1 (GLP-1) is an endogenous incretin hormone. Liraglutide, a GLP-1 receptor agonist, can lower blood sugar by increasing insulin production and inhibiting the production of glucagon. This study researched the bioequivalence and safety of the test and reference drugs in healthy Chinese subjects. RESEARCH DESIGN AND METHODS: Subjects (N = 28) were randomly divided into group A and group B at a ratio of 1:1 for a two-cycle cross-over study. There was single dose per cycle with subcutaneous injection of the test and reference drugs, respectively. The washout was set at 14 days. Plasma drug concentrations were detected by specific liquid chromatography and tandem mass spectrometry (LC-MS/MS) assays. Statistical analysis of major pharmacokinetic (PK) parameters was conducted to assess drug bioequivalence. In addition, we evaluated the safety of the drugs throughout the trial. RESULTS: The geometric mean ratios (GMRs) of Cmax, AUC0-t, and AUC0-∞ for the test and reference drugs were 107.11%, 106.56%, 106.09%, respectively. The 90% confidence intervals (CIs) were all within 80%-125%, meeting the bioequivalence standards. In addition, both had good safety in this study. CONCLUSION: The study shows that the two drugs had similar bioequivalence and safety. CLINICAL TRIAL REGISTRATION: DCTR: CTR20190914; ClinicalTrials.gov: NCT05029076.


Assuntos
População do Leste Asiático , Liraglutida , Humanos , Área Sob a Curva , China , Cromatografia Líquida , Estudos Cross-Over , Liraglutida/administração & dosagem , Liraglutida/efeitos adversos , Liraglutida/sangue , Liraglutida/farmacocinética , Espectrometria de Massas em Tandem , Equivalência Terapêutica , Injeções Subcutâneas , Monitoramento de Medicamentos
19.
Sci Rep ; 12(1): 4189, 2022 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-35264674

RESUMO

Haze has reached epidemic levels in many Chinese cities in recent years. Few studies have explored the determinants and heterogeneity of PM2.5. This paper investigates the spatiotemporal characteristics of PM2.5 through spatial analytical methods based on aerosol optical depth data from the Yangtze River Economic Belt (YREB) between 2000 and 2017. Geographically weighted regression and geodetector models were applied to assess the heterogeneity of key factors influencing PM2.5. The results indicate that the annual concentrations of PM2.5 in the YREB were 23.49-37.37 µg/m3, with an initial increase and a later decrease. PM2.5 pollution showed a diagonal high spatial distribution pattern in the northeast and a low spatial distribution in the southwest, as well as a noticeable spatial convergence. The spatial variability of PM2.5 was enlarged, and its main fractal dimension was in the northeast-southwest direction. There were clear spatiotemporal variations in the impacts of natural and anthropogenic factors on PM2.5. Our findings contribute to a better understanding of the impact mechanisms of PM2.5 and the geographic factors that form persistent and highly polluted areas and imply that more specific coping strategies need to be implemented in various areas toward successful particulate pollution prevention and control.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Monitoramento Ambiental/métodos , Material Particulado/análise , Rios
20.
Fundam Res ; 2(5): 674-681, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38933122

RESUMO

Combining the physical advantages of two-dimensional (2D) inorganic nanosheets and the modular design and programmed structure of metal-organic frameworks (MOFs), 2D MOFs remain at the forefront of functional material research. Despite tremendous efforts, precise control in the synthesis of 2D nonlayered MOFs with predesigned topology for desired applications remains challenging. Success in the bottom-up synthesis of 2D nonlayered MOFs via ligand exchange motivated us to incorporate partial BTC (BTC = 1,3,5-benzenetricarboxylate) ligand dissociation and CO2 capped coordination into the top-down treatment of bulk Cu-BTC MOF, leading to successful conversion of a 3D nonlayered network to a 2D Cu-based topological structure. Notably, a supercritical CO2-containing solvent mixture is employed to provide the desired defect and coordination engineering. Thus, our work introduces a new top-down concept based on modulated synthesis to fabricate high-quality 2D nonlayered MOFs for the first time.

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