The upper bound of enzyme concentration for accurately estimating the parameters in Michaelis-Menten (MM) equation is not completely determined and still under discussion, even though many ...researchers have investigated the equation’s validity for a long time. In the paper, we broadly investigated the correlation between the system of ordinary differential equations for monosubstrate irreversible enzyme reaction (HMM-system) and its derivative MM equation focusing on the relationship between initial enzyme concentration E0 and Michaelis constant Km by numerical simulation. According to the results, the initial reaction velocity v0 is still a function of initial substrate concentration S0 at E0<Km. The function is identical to the MM equation at E0≦0.01Km, while it is described as a new type of equation at 0.01Km≦E0<Km. This function is of great significance in enzyme assays as a comprehensive approximation for the HMM-system.
•A new comprehensive approximation for the HMM-system at E0<Km.•The MM equation for enzyme kinetics at E0≦0.01Km.•The new equation for enzyme kinetics at 0.01Km≦E0<Km.•One can characterize enzymes in more detail through initial rate experiment.
Transient stability and short-term voltage stability have successively attracted the attention of electric power industry. This paper proposes a novel systematic approach for dynamic VAR planning to ...improve short-term voltage stability level and transient stability level. The dynamic VAR planning problem is formulated as a multi-objective optimization (MOO) model with objectives including investment cost, short-term voltage stability level, and transient stability level. To reduce the complexity of the proposed MOO model, K-means clustering-based severe contingencies selection and global sensitivity analysis-based potential buses selection are employed, leading to a simplified MOO model. The combination of a surrogate modeling technique called support vector regression and the multi-objective evolutionary algorithm (MOEA) are then used to solve the simplified MOO model, considering both the accuracy of models and the optimization computation cost. This combination makes it feasible to perform multiple runs of MOEAs for weakening the effect of the MOEA's randomness to optimal results and offering more diverse Pareto-optimal solutions for decision makers. Simulations are carried on the IEEE 39-bus system and a real power grid of China, illustrating that our methodology is reliable with high efficiency.
Enhancer RNAs (eRNAs) are demonstrated to be closely associated with tumourigenesis and cancer progression. However, the role of eRNAs in lung adenocarcinoma (LUAD) remains largely unclear. Thus, a ...comprehensive analysis was constructed to identify the key eRNAs, and to explore the clinical utility of the identified eRNAs in LUAD.
First, LUAD expression profile data from the Cancer Genome Atlas (TCGA) dataset and eRNA-relevant information were integrated for Kaplan-Meier survival analysis and Spearman's correlation analysis to filtered the key candidate eRNAs that was associated with survival rate and their target genes in LUAD. Then, the key eRNA was selected for subsequent clinical correlation analysis. KEGG pathway enrichment analyses were undertaken to explore the potential signaling pathways of the key eRNA. Data from the human protein atlas (HPA) database were used to validate the outcomes and the quantitative real time-polymerase chain reaction (qRT-PCR) analysis was conducted to measure eRNA expression levels in tumor tissues and paired normal adjacent tissues from LUAD patients. Finally, the eRNAs were validated in pan-cancer.
As a result, TBX5-AS1 was identified as the key eRNA, which has T-box transcription factor 5 (TBX5) as its regulatory target. KEGG analysis indicated that TBX5-AS1 may exert a vital role via the PI3K/AKT pathway, Ras signaling pathway, etc. Additionally, the qRT-PCR results and the HPA database indicated that TBX5-AS1 and TBX5 were significantly downregulated in tumour samples compared to matched-adjacent pairs. The pan-cancer validation results showed that TBX5-AS1 was associated with survival in four tumors, namely, adrenocortical carcinoma (ACC), LUAD, lung squamous cell carcinoma (LUSC), and uterine corpus endometrial carcinoma (UCEC). Correlations were found between TBX5-AS1 and its target gene, TBX5, in 26 tumor types.
Collectively, our results indicated that TBX5-AS1 may be a potential prognostic biomarker for LUAD patients and promote the targeted therapy of LUAD.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Heterojunctions modulated internal electric field (IEF) usually result in suboptimal efficiencies in carrier separation and utilization because of the narrow IEF distribution and long ...migration paths of photocarriers. In this work, we report distinctive bismuth oxyhydroxide compound nanorods (denoted as BOH NRs) featuring surface-exposed open channels and a simple chemical composition; by simply modifying the bulk anion layers to overcome the limitations of heterojunctions, the bulk IEF could be readily modulated. Benefiting from the unique crystal structure and the localization of valence electrons, the bulk IEF intensity increases with the atomic number of introduced halide anions. Therefore, A low exchange ratio (~10%) with halide anions (I
–
, Br
–
, Cl
–
) gives rise to a prominent elevation in carrier separation efficiency and better photocatalytic performance for benzylamine coupling oxidation. Here, our work offers new insights into the design and optimization of semiconductor photocatalysts.
In order to study the influence of subarea excavation on the deformation and stress behavior of a subway foundation pit, the deep horizontal wall displacement, supporting axial force and surface ...deformation were measured and compared with other similar pit cases according to the case of a soft soil deep foundation pit for a metro station in Hangzhou. The results of the theoretical and experimental studies show that zoned excavation can reduce the aspect ratio of a single foundation pit and then the spatial effect of small excavation can be mobilized, which can effectively control lateral wall deformation and wall deformation. Higher stiffness can strengthen the integrity of the foundation pit and provide more lateral force to prevent excessive axial force fluctuation in the deep foundation pit, and its restraining effect is greater than the first excavation foundation pit. The difference in the distribution of buildings on both sides of the long and narrow pit will lead to a different deformation of the walls on both sides, which warrants attention in the design and construction.
Direct construction of fully alkyl-substituted tertiary chiral centers remote to activating groups is highly challenging and desirable. Herein, a Ni-catalyzed enantioselective hydroalkylation of ...unactivated alkenes with unactivated alkyl halides at room temperature is reported, providing a general and practical access to fully alkyl-substituted tertiary stereogenic carbon centers not adjacent to activating groups. This reaction undergoes the regio- and stereoselective hydrometalation of unactivated alkenes with a nontrivial Markovnikov selectivity, followed by the cross-coupling with unactivated alkyl electrophiles to access trialkyl tertiary saturated stereogenic centers not adjacent to activating groups. The mild and robust conditions enable the use of terminal and internal unactivated alkenes and unactivated primary and secondary alkyl, benzyl, and propargyl halides to construct diverse trialkyl tertiary stereogenic carbon centers with broad functional group tolerance. Moreover, experimental investigations support the reaction undergoing irreversible and stereoselective hydrometalation of alkenes. Density functional theory calculations provide further insights into the reaction mechanism, suggesting a stereoselective migration insertion of alkenes with Ni(II)–H species. Finally, the origin of the regio- and enantioselectivities is also investigated.
The temporal response of CdZnTe (CZT) detector to <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray is experimentally studied in this article. Infrared (IR) ...illumination is utilized to improve the performance of CZT detector. The results show that with no IR illumination operated on the CZT detector, the output signal of the CZT detector appears as a short overshoot process (sharp peak) at the beginning of stable <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray irradiation. After the sharp peak, a decay process follows, and finally, a stable output of CZT detector is achieved. IR illumination can eliminate the instability of CZT detector under <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray irradiation, such as the output overshoot of detector (sharp peak) during the transition state. With the increase of IR illumination intensity, the sharp peak disappears gradually and the temporal response of CZT detector follows the intensity of <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray irradiation without transition state. The fitting time constant of the sharp peak is in good consistency with the typical detrapping lifetime on the order of seconds. The stable current of CZT <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray detector can be improved by 8.2% due to IR illumination, which can also be explained by the prefilling effects of IR illumination on the defect level. The sharp peak in the temporal response of CZT detector is probably caused by the deep level, related to the Te antisite-related deep donors. The current uncertainty of CZT <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray detector under IR illumination is smaller than 1.4%, which is small enough to be ignored. The flux rate response of CZT detector can also be improved by IR illumination. This study will provide significant supports for the further application of CZT material in radiation measurements.
The reconstruction of concrete microstructure with computed tomography (CT) images is a challenging problem because concrete is associated with poly-mineral aggregates, various aggregate sizes, high ...volume fraction of aggregates, rough aggregate surface, small and large connected aggregates, and others. To tackle some of the issues in concrete microstructure reconstruction, CT images are obtained using the complementarity of X-ray and neutron while a recursive aggregate segmentation by erosion and reconstitution (RASER) process is proposed to separate connected aggregates for both 3D and 2D. The RASER algorithm is based on the recursive and iterative processes of erosion and reconstitution of aggregate surface while increasing the eroding layer thickness until a constant number of aggregates is reached. Based on the RASER technique, the 3D segmented concrete microstructure illustrates that aggregates are not skewed based on their sizes and locations while neither under- nor over-segmented in this study. Furthermore, we found that most 2D microstructure analysis can lead to over-segmentation because of artificial section segmentation and rough aggregate surface.
The efficiency of sludge dewatering is limited by extracellular polymeric substances (EPS) during biodrying. This study investigated the effect of photocatalysis-mediated EPS degradation on sludge ...dewatering performance during the sludge biodrying process. The photocatalysis of municipal sludge was first carried out to choose a cost-efficient catalyst. Then sludge biodrying tests were performed using TiO2-coated amendment (TCA) and uncoated amendment (TUCA) as the control. Municipal sludge photocatalysis results showed that using TiO2 could efficiently degrade carbohydrates and proteins in the EPS within 60 min. After 20-day biodrying, photocatalysis significantly promoted a reduction in the moisture content and EPS by 17.64% and 6.88%, respectively. The surface-enhanced Raman scattering (SERS) intensities of the C–C–O symmetric stretching vibration peak of D-lactose and the C–S stretching vibration peak of cysteine were significantly decreased by approximately 33.19% and 44.76%, respectively, indicating that photocatalysis indeed promoted the reduction of polysaccharides and cysteine in the EPS, especially after the thermophilic phase. The hydrophilic amino acid content decreased by 23.02%, verifying that photocatalysis could improve EPS hydrophobicity. Consequently, municipal sludge biodrying coupled with photocatalysis promotes sludge EPS degradation and enhances sludge dewaterability, improving the efficiency of sludge biodrying.
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•TiO2 coated amendment was used during sludge biodrying with photocatalysis.•Polysaccharide in extracellular polymeric substance degraded after thermophilic phase.•Cysteine C–S stretching vibration intensity reduced 29.44% after thermophilic phase.•Significant degradation of hydrophilic lysine and cysteine promoted sludge dewatering.•Using TiO2 coated amendment biodrying showed high humification and low biotoxicity.
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