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► Unnatural catalytic activity of trypsin from porcine pancreas for direct asymmetric aldol reaction was discovered. ► Mechanism of trypsin-catalyzed aldol reaction was hypothesized. ...► This enzymatic promiscuity widens the application of trypsin to new chemical transformations.
Unnatural catalytic activity of trypsin from porcine pancreas for direct asymmetric aldol reaction was discovered. The reactions between aromatic aldehydes and various ketones gave products in moderate yields and enantioselectivities in the presence of a small amount of water. The influences of solvent, water content, temperature, mole ratio of substrates, and enzyme concentration were investigated. The mechanism of trypsin-catalyzed aldol reaction was discussed. This enzymatic promiscuity widens the application of trypsin to new chemical transformations.
Parkinson's disease (PD) is characterized by the selective death of dopaminergic neurons in the substantia nigra pars compacta. Oxidative stress-induced neuron loss is thought to play a crucial role ...in the pathogenesis of PD. Previous work from our group suggests that 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), an active component extracted from a traditional Chinese herb, Polygonum multiflorum thunb, can attenuate 1-methyl-4-phenyl pyridium-induced apoptosis in the neuronal cell line PC12, by inhibiting reactive oxygen species generation and modulating c-Jun N-terminal kinases (JNK) activation. Here, we investigated the protective effects of TSG against 1-methyl-4-phenyl-1,2,3,6-tetrahydropypridine (MPTP)-induced loss of tyrosine hydroxylase positive cells in mice and the underlying mechanisms. The results showed that MPTP-induced loss of tyrosine hydroxylase positive cells and reactive oxygen species generation were prevented by TSG in a dose-dependent manner. The reactive oxygen species scavenger N-acetylcysteine could also mitigate reactive oxygen species generation. Moreover, JNK and P38 were activated by MPTP, but extracellular signal-regulated protein kinases phosphorylation did not change after MPTP treatment. TSG at different doses blocked the activation of JNK and P38. The protective effect of TSG was also associated with downregulation of the bax/bcl-2 ratio, reversed the release of cytochrome c and smac, and inhibited the activation of caspase-3, -6, and -9 induced by MPTP. In conclusion, our studies demonstrated that the protective effects of TSG in the MPTP-induced mouse model of PD are involved, at least in part, in controlling reactive oxygen species-mediated JNK, P38, and mitochondrial pathways.
Purpose Metabolic syndrome and insulin resistance have been linked to increased risk of occurrence and mortality of hepatocellular carcinoma (HCC). Recently, retinol-binding protein 4 (RBP4) was ...clarified as a specific serological marker of insulin resistance. The aim of this study was to determine whether serum RBP4 could be used as a potential marker for predicting prognosis in patients with HCC after curative resection. Methods Western immunoblotting and Enzyme-linked immunosorbent assay were used to measure the RBP4 expression in cell lines, supernatant, and serum. Serum RBP4 levels were compared with clinicopathological features and outcomes of patients with HCC. Furthermore, we investigated the impact of serum RBP4 level, serum C-peptide level, and HOMA-IR on overall survival (OS) and disease-free survival (DFS) of patients with HCC in the training cohort (156 patients with HCC), and then were validated in the validation cohort (105 patients with HCC). Results RBP4 protein overexpressed in HCC cell lines compared with normal liver cell line (P < 0.001) and correlated with metastatic potential. Serum RBP4 levels were associated with OS hazard ratio (HR) = 2.208, P < 0.001 and DFS (HR = 1.878, P = 0.029) of patients with HCC. By multivariate analysis, the serum RBP4 level was identified as an independent factor for OS (HR = 2.170, P = 0.004) and DFS (HR = 1.769, P = 0.037) of patients with HCC. The prognostic value of serum RBP4 level was confirmed in the validation cohort. Conclusions The serum RBP4 level is potential to be a useful prognostic factor for HCC after curative resection.
As the core functional layer of perovskite solar cells, the serious issues of the CH3NH3PbI3 film related to the long-term stability and its rapid degradation when exposed to the environment should ...be investigated deeply. In this study, the variation of phase construction, light absorption ability and fluorescence quenching ability during the long time aging process have been monitored. The results show that the degradation process is composed of the original serious fluorescence quenching and the lag behind phase decomposition. Then, the intrinsic physical mechanism has been obtained by the first-principles simulation of defect properties, which shows that the original serious fluorescence emission quenching is attributed to the deep level defects with low formation energies (such as VPb and IPb); meanwhile, the lag behind phase decomposition is caused by the easy ionic diffusion; for example, the diffusion activation energy of the iodine ion is 0.286 eV. The results illustrate that both the defect passivation and prevention of the ion diffusion are necessary for achieving a stable perovskite film.
Upper airway assessment requires a fully-automated segmentation system for complete or sub-regional identification. This study aimed to develop a novel Deep Learning (DL) model for accurate ...segmentation of the upper airway and achieve entire and subregional identification.
Fifty cone-beam computed tomography (CBCT) scans, including 24,502 slices, were labelled as the ground truth by one orthodontist and two otorhinolaryngologists. A novel model, a lightweight multitask network based on the Swin Transformer and U-Net, was built for automatic segmentation of the entire upper airway and subregions. Segmentation performance was evaluated using Precision, Recall, Dice similarity coefficient (DSC) and Intersection over union (IoU). The clinical implications of the precision errors were quantitatively analysed, and comparisons between the AI model and Dolphin software were conducted.
Our model achieved good performance with a precision of 85.88–94.25%, recall of 93.74–98.44%, DSC of 90.95–96.29%, IoU of 83.68–92.85% in the overall and subregions of three-dimensional (3D) upper airway, and a precision of 91.22–97.51%, recall of 90.70–97.62%, DSC of 90.92–97.55%, and IoU of 83.41–95.29% in the subregions of two-dimensional (2D) crosssections. Discrepancies in volume and area caused by precision errors did not affect clinical outcomes. Both our AI model and the Dolphin software provided clinically acceptable consistency for pharyngeal airway assessments.
The novel DL model not only achieved segmentation of the entire upper airway, including the nasal cavity and subregion identification, but also performed exceptionally well, making it well suited for 3D upper airway assessment from the nasal cavity to the hypopharynx, especially for intricate structures.
This system provides insights into the aetiology, risk, severity, treatment effect, and prognosis of dentoskeletal deformities and obstructive sleep apnea. It achieves rapid assessment of the entire upper airway and its subregions, making airway management—an integral part of orthodontic treatment, orthognathic surgery, and ENT surgery—easier.
Hollow zeolite single crystals have received extensive attention due to their unique cavities and outstanding catalytic performance. Although many kinds of zeolites have been synthesized with hollow ...structures, the related synthesis of hollow SSZ-13 zeolites has not been reported yet. In this work, we first synthesized hollow zeolite SSZ-13 single crystals by a simple and economical strategy without additional templates, which involves adjusting the spatial chemistry distribution of elements throughout the crystals to create Al-zoned and forming cavity by selective desiliconization. Furthermore, we doped the synthesized hollow zeolite SSZ-13 with copper, and the hollow Cu-SSZ-13 zeolite exhibits an enhanced catalytic activity of selective catalytic reduction (SCR) of NOx with NH3 compared with the traditional solid Cu-SSZ-13.
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•Hollow SSZ-13 zeolites are synthesized by one-pot method.•Synthetic process involves creating Al-zoned and selective desiliconization.•The Al-zoned is created by adjusting the spatial distribution of Al elements in the crystal.•NH3-SCR activity of hollow Cu-SSZ-13 is better than conventional solid Cu-SSZ-13.
•Ionic liquid BMIMPF6 has been encapsulated in polysulfone.•The microcapsules containing ionic liquid have been used for the first time to extract caprolactam from water.•The adsorption kinetics and ...sorption isotherm have also been discussed.
Polysulfone (PSF) microcapsules containing ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) as extractant have been successfully prepared using solvent evaporation method and used in removing caprolactam from water. The results showed that ionic liquid BmimPF6 was successfully encapsulated by PSF and the encapsulation capacity of 32.44% was achieved. Systematic studies on the effect of concentration of ammonium sulfate solution, caprolactam adsorption equilibrium, kinetic and isotherm by PSF@BmimPF6 capsules were carried out. The results showed that increasing the concentration of ammonium sulfate solution, initial concentration of the caprolactam and the adsorption time were good for adsorption. The adsorption kinetics of caprolactam followed pseudo-second-order model and the Freundlich equation described the adsorption process better than the Langmuir equation. These PSF@BmimPF6 capsules showed potential ability in the treatment of wastewater.
Characterized by the noticeable seasonal patterns of canopy photosynthesis, mid-to-high latitude forests are sensitive to climate change and crucial for understanding the global carbon cycle. To ...monitor the seasonal cycle of the canopy photosynthesis from space, several remotely sensed indexes, such as normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), and leaf area index (LAI) have been implemented within the past decades. Recently, satellite-derived sun-induced fluorescence (SIF) has shown great potential of providing retrievals that are more related to photosynthesis process. However, the potentials of different canopy measurements have not been thoroughly assessed in the context of recent advances of new satellites and proposals of improved indexes. At 15 forested sites, we present a cross-platform intercomparison of one emerging remote sensing based index of phenology index (PI) and two SIF datasets against the conventional indexes such as NDVI, EVI, and LAI to capture the seasonal cycles of canopy photosynthesis. NDVI, EVI, LAI, and PI were calculated from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements, while SIF were evaluated from Global Ozone Monitoring Experiment-2 (GOME-2) and Orbiting Carbon Observatory-2 (OCO-2) observations. Results indicated that GOME-2 SIF was highly correlated with gross primary production (GPP) and absorbed photosynthetically active radiation during the growing seasons. The SIF-GPP relationship can generally be considered linear at the 16-day scale. Key phenological metrics such as start of the seasons and end of the seasons captured by SIF from GOME-2 and OCO-2 matched closely with photosynthesis phenology as inferred by GPP. However, the applications of OCO-2 SIF for phenological studies may be limited only for a small range of sites (at site-level) due to a limited spatial sampling. Among the MODIS estimations, PI and NDVI provided most reliable predictions of start of growing seasons, while no indexes accurately captured the end of growing seasons.
The original EC GPP and OCO-2 SIF with the fitted seasonal cycles and predicted SOS and EOS at six forested sites. Display omitted
•Phenological metrics from 2 SIF sets and 4 vegetation indexes were intercompared.•Remotely sensed SIF were highly correlated with GPP in mid-to-high latitude forests.•The SIF-GPP relationships can be generally considered linear at 16-day scale.•PI and NDVI provided reliable predictions of start of seasons among MODIS indexes.•Limitations remained for OCO-2 SIF to extract photosynthesis phenology at site-level.
Stressed plants and polymer production can emit many unsaturated volatile organic esters (UVOEs). However, secondary organic aerosol (SOA) formation of UVOEs remains unclear, especially under complex ...ambient conditions. In this study, we mainly investigated ethyl methacrylate (EM) ozonolysis. Results showed that a substantial increase in secondary H.sub.2 SO.sub.4 particles promoted SOA formation with increasing SO.sub.2 . An important reason was that the homogeneous nucleation of more H.sub.2 SO.sub.4 at high SO.sub.2 level provided greater surface area and volume for SOA condensation. However, increased primary H.sub.2 SO.sub.4 with seed acidity enhanced EM uptake but reduced SOA formation. This was ascribed to the fact that the ozonolysis of more adsorbed EM was hampered with the formation of surface H.sub.2 SO.sub.4 at higher particle acidity. Moreover, the increase in secondary H.sub.2 SO.sub.4 particle via homogeneous nucleation favored to the oligomerization of oxidation products, whereas the increasing of primary H.sub.2 SO.sub.4 with acidity in the presence of seed tended to promote the functionalization conversion products. This study indicated that the role of increased H.sub.2 SO.sub.4 to EM-derived SOA may not be the same under different ambient conditions, which helps to advance our understanding of the complicated roles of H.sub.2 SO.sub.4 in the formation of EM-derived SOA.
Stressed plants and polymer production can emit many unsaturated volatile organic esters (UVOEs). However, secondary organic aerosol (SOA) formation
of UVOEs remains unclear, especially under complex ...ambient conditions. In this study, we mainly investigated ethyl methacrylate (EM) ozonolysis.
Results showed that a substantial increase in secondary H2SO4 particles promoted SOA formation with increasing SO2. An
important reason was that the homogeneous nucleation of more H2SO4 at high SO2 level provided greater surface area and volume
for SOA condensation. However, increased primary H2SO4 with seed acidity enhanced EM uptake but reduced SOA formation. This was
ascribed to the fact that the ozonolysis of more adsorbed EM was hampered with the formation of surface H2SO4 at higher particle
acidity. Moreover, the increase in secondary H2SO4 particle via homogeneous nucleation favored to the oligomerization of oxidation
products, whereas the increasing of primary H2SO4 with acidity in the presence of seed tended to promote the functionalization
conversion products. This study indicated that the role of increased H2SO4 to EM-derived SOA may not be the same under different ambient
conditions, which helps to advance our understanding of the complicated roles of H2SO4 in the formation of EM-derived SOA.
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