Search

Direct synthesis of dimethyl carbonate (DMC) from CO2 and CH3OH holds significant economic and environmental value. Numerous catalysts have been employed for this reaction, yet further enhancement of its activity requires a deeper understanding of the catalyst's structure–activity relationship and catalytic mechanism. In this study, we utilized structurally well-defined and highly tunable MOF-808 as a research platform. Functionalizing MOF-808 with ethylenediamine (MOF-808-ED) boosted the space time yield of DMC from 3.25 mmol g−1 h−1 to 7.23 mmol g−1 h−1. The experimental results demonstrate that the reaction involves acid–base synergistic catalysis, where an appropriate balance of acid–base site content is crucial for CO2 and CH3OH to produce DMC, as it facilitates the formation of the key intermediates (CH3OCOO*). Additionally, the nucleophilicity of N is stronger than that of O, further promoting the catalyst's enrichment and activation of CO2. Finally, employing in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) testing, we elucidated the mechanism by which the MOF-808-ED catalyst, with –NH2 as base sites and Zr as acid sites, facilitates the synergistic catalysis of the reaction. This study provides insights into the synergistic effects of acid–base sites on the synthesis of DMC from CO2 and methanol, offering valuable guidance for the development of high-performance catalysts. [ABSTRACT FROM AUTHOR]

Climate change will have various impacts on the survival and development of species, and it is important to explore whether plants can adapt to future climate conditions. Dipteronia dyeriana is an endangered species with a narrow distribution in Yunnan, characterized by a small population size. However, studies on its current distribution and the impact of climate change on its future survival and distribution are very limited. In this study, the current and future (2050 and 2090) potential habitats under the SSP1-2.6, SSP3-7.0, and SSP5-8.5 scenarios were predicted using both maximum entropy (MaxEnt) and random forest (RF) models based on the current range points of D. dyeriana, soil, topographical, land cover, and climate data. The results showed that the RF model demonstrated significantly higher AUC, TSS, and Kappa scores than the MaxEnt model, suggesting high accuracy of the RF model. Isothermality (bio_3), minimum temperature of the coldest month (bio_6), and annual precipitation (bio_12) are the main environmental factors affecting the distribution of D. dyeriana. At present, the high suitability area of D. dyeriana is mainly concentrated in the eastern part of Yunnan Province and part of southern Tibet, covering an area of 3.53 × 104 km2. Under future climate change scenarios, the total area suitable for D. dyeriana is expected to increase. Although, the highly suitable area has a tendency to decrease. With regards to land use, more than 77.53% of the suitable land area (29.67 × 104 km2) could be used for D. dyeriana planting under different SSP scenarios. In 2090, the centroid shifts of the two models exhibit a consistent trend. Under the SSP1-2.6 scenario, the centroids transfer to the southeast. However, under the SSP3-7.0 and SSP5-8.5 scenarios, the centroids of high suitability areas migrate toward the northwest. In summary, this study enhances our understanding of the influence of climate change on the geographic range of D. dyeriana and provides essential theoretical backing for efforts in its conservation and cultivation. [ABSTRACT FROM AUTHOR]

Non-centrosymmetric (NCS) structure is an indispensable prerequisite for second-order nonlinear optical (NLO) material. Currently, the mainstream approach for designing new NCS structures still relies on chemical substitution, necessitating an urgent infusion of fresh ideas. In this work, two isomorphic sulfides AeMn6Ga6S16 (Ae = Ca, 1; Sr, 2) are afforded by modifying the skeleton of centrosymmetric (CS) Mn2Ga2S5via introducing strong electropositive alkaline-earth cations. Concretely, the incorporation of Ca2+/Sr2+ cations allows the elementary [MnGaS9]∞ chains to reconfigure into bumpy [MnS6]-[GaS4] layers in a new engagement manner, thus enabling the conversion from CS to NCS structure. Such modifications cause not only strong second-harmonic generation (SHG) responses (∼1.5 × benchmark AgGaS2 @1,700 nm), but also significantly feasible bandgaps (2.60–2.64 eV) compared to the sulfide Mn2Ga2S5 (1.36 eV), which ultimately facilitate ultrahigh laser-induced damage thresholds (4.4–6.6 × AgGaS2 @1,064 nm for compounds 1 and 2). The present study offers an ingenious approach for the transformation of CS to NCS structure. [ABSTRACT FROM AUTHOR]

Objective: Diabetes mellitus (DM) is a global epidemic; comorbid depressive symptoms are highly prevalent worldwide and commonly manifests as physical symptoms, including functional dyspepsia (FD), a gastrointestinal psychosomatic disorder. This study aimed to explore the effects of comorbid depressive symptoms and DM on FD in older patients. Methods: In total, 420 older patients with DM completed measures of depression, anxiety, and FD. Relevant demographic characteristics and medical information were self-reported and obtained from the hospital information system. Results: Among older patients with DM, 30.48% had depressive symptoms. Patients with depressive symptoms were more likely to have FD than those without (42.19% vs. 20.21%, P = .000). Dyspepsia symptoms were more frequent in patients with depression (P = .022). The greater the amount of dyspepsia symptoms, the higher the depression symptoms score (P = .000). Furthermore, dyspepsia symptoms were positively correlated with depressive symptoms (r values were 0.292, 0.311, 0.297, 0.369; all had P < .05). Both FD subtypes, postprandial distress, and epigastric pain syndromes affected depressive symptoms (P < .05). Smoking was significantly associated with FD (P < .05). Diabetes mellitus complications, such as diabetic neuropathy, different therapeutic methods, and anxiety symptoms, influenced FD overlap (x² values were 6.298, 16.314, and 30.744; P < .05). Anxiety (odds ratio=1.832, 95% Confidence Intervals (CI) 1.185-2.834) was a risk factor for FD in comorbid depressive symptoms and diabetes (P < .05). Conclusion: Comorbid depressive symptoms and DM overlapped with physical symptoms, such as FD, in older patients with DM. Lifestyle, diabetic factors, and anxiety were the associated risk factors. [ABSTRACT FROM AUTHOR]