Quasi van der Waals Epitaxy of Single Crystalline GaN on Amorphous SiO2/Si(100) for Monolithic Optoelectronic Integration

The realization of high quality (0001) GaN on Si(100) is paramount importance for the monolithic integration of Si-based integrated circuits and GaN-enabled optoelectronic devices. Nevertheless, thorny issues including large thermal mismatch and distinct crystal symmetries typically bring about uncontrollable polycrystalline GaN formation with considerable surface roughness on standard Si(100). Here a breakthrough of high-quality single-crystalline GaN film on polycrystalline SiO2/Si(100) is presented by quasi van der Waals epitaxy and fabricate the monolithically integrated photonic chips. The in-plane orientation of epilayer is aligned throughout a slip and rotation of high density AlN nuclei due to weak interfacial forces, while the out-of-plane orientation of GaN can be guided by multi-step growth on transfer-free graphene. For the first time, the monolithic integration of light-emitting diode (LED) and photodetector (PD) devices are accomplished on CMOS-compatible SiO2/Si(100). Remarkably, the self-powered PD affords a rapid response below 250 µs under adjacent LED radiation, demonstrating the responsivity and detectivity of 2.01 × 105 A/W and 4.64 × 1013 Jones, respectively. This work breaks a bottleneck of synthesizing large area single-crystal GaN on Si(100), which is anticipated to motivate the disruptive developments in Si-integrated optoelectronic devices.

[Impact of COVID-19 on primary percutaneous coronary intervention in patients with acute ST segment elevation myocardial infarction in Beijing]

Objective: To investigate the impact of COVID-19 on treatment of patients with acute ST segment elevation myocardial infarction(STEMI) undergoing primary percutaneous coronary intervention(PPCI). Methods: This was a multicenter retrospective study. STEMI patients undergoing PPCI from January 1, 2019 to December 31, 2021 were selected, based on the data of Xinnaolvsetongdao App. Clinical data and treatment time indicators, including symptom to first medical contact (S-FMC), symptom to door (StoD), first medical contact to ECG (FMC-ECG), first medical contact to guide wire (FMC-W), door to balloon (DtoB) and total ischemic time in 2019, 2020 and 2021 were compared. STEMI patients aged<60 years were sub-grouped as the young and middle-aged group, and STEMI patients aged≥60 years were sub-grouped as the elderly group. Results: A total of 7 435 (3 305 in 2019, 1 796 in 2020 and 2 334 in 2021) STEMI patients aged (59.6±12.6) years undergoing PPCI were included in this analysis. There were 5 990 males. For STEMI patients with PPCI in 2019, 2020 and 2021, FMC-ECG was 3 (1, 5) min, 3(1, 7) min and 4 (1, 7) min. FMC-W was 73 (56, 87) min, 78 (62, 95) min and 77 (62, 87) min. DtoB was 73 (56, 85) min, 78 (62, 95) min and 77 (62, 86) min. Total ischemic time was 189 (130, 273) min, 196 (138, 295) min and 209 (143, 276) min. FMC-ECG, FMC-W, DtoB and total ischemic time were longer in 2020 and 2021 than in 2019 (all P<0.05). The proportions of patients with FMC-ECG≤10 min (88.4% (1 588/1 796) vs. 92.7% (3 064/3 305), P<0.05), FMC-W≤120 min (87.9% (1 579/1796) vs. 91.7% (3 030/3 305), P<0.05) and DtoB≤90 min (72.3% (1 298/1 796) vs. 80.8% (2 672/3 305), P<0.05) were lower in 2020 than in 2019, whereas no differences were observed in the proportions of patients with FMC-ECG≤10 min (91.3% (2 131/2 334) vs. 92.7% (3 064/3 305), P=0.054), FMC-W≤120 min (92.0% (2 148/2 334) vs. 91.7% (3 030/3 305), P=0.635) and DtoB≤90 min (80.0% (1 867/2 334) vs. 80.8% (2 672/3 305), P=0.424) in 2021 compared with 2019. In the subgroup analysis, the proportions of patients with FMC-ECG≤10 min, FMC-W≤120 min and DtoB≤90 min were lower in the elderly group than in young and middle-aged group in 2019 (all P<0.05). The proportions of patients with FMC-W≤120 min and DtoB≤90 min were lower in the elderly group than in young and middle-aged group in 2021(all P<0.05). No differences were observed in the proportions of patients with FMC-ECG≤10 min, FMC-W≤120 min and DtoB≤90 min between the two group in 2020 (all P>0.05). Conclusions: Affected by the COVID-19, there is a reduction in the number of PPCI cases and treatment delays in STEMI patients, especially in the elderly. After adjusting the treatment strategy and widely applying the Xinnaolvsetongdao APP, the above indicators are significantly improved in 2021 as compared with 2020.

QSAR and Chemical Read-Across Analysis of 370 Potential MGMT Inactivators to Identify the Structural Features Influencing Inactivation Potency

O6-methylguanine-DNA methyltransferase (MGMT) constitutes an important cellular mechanism for repairing potentially cytotoxic DNA damage induced by guanine O6-alkylating agents and can render cells highly resistant to certain cancer chemotherapeutic drugs. A wide variety of potential MGMT inactivators have been designed and synthesized for the purpose of overcoming MGMT-mediated tumor resistance. We determined the inactivation potency of these compounds against human recombinant MGMT using [3H]-methylated-DNA-based MGMT inactivation assays and calculated the IC50 values. Using the results of 370 compounds, we performed quantitative structure-activity relationship (QSAR) modeling to identify the correlation between the chemical structure and MGMT-inactivating ability. Modeling was based on subdividing the sorted pIC50 values or on chemical structures or was random. A total of nine molecular descriptors were presented in the model equation, in which the mechanistic interpretation indicated that the status of nitrogen atoms, aliphatic primary amino groups, the presence of O-S at topological distance 3, the presence of Al-O-Ar/Ar-O-Ar/R..O..R/R-O-C=X, the ionization potential and hydrogen bond donors are the main factors responsible for inactivation ability. The final model was of high internal robustness, goodness of fit and prediction ability (R2pr = 0.7474, Q2Fn = 0.7375-0.7437, CCCpr = 0.8530). After the best splitting model was decided, we established the full model based on the entire set of compounds using the same descriptor combination. We also used a similarity-based read-across technique to further improve the external predictive ability of the model (R2pr = 0.7528, Q2Fn = 0.7387-0.7449, CCCpr = 0.8560). The prediction quality of 66 true external compounds was checked using the "Prediction Reliability Indicator" tool. In summary, we defined key structural features associated with MGMT inactivation, thus allowing for the design of MGMT inactivators that might improve clinical outcomes in cancer treatment.

Comprehensive molecular evaluation of the histone methyltransferase gene family and their important roles in two-line hybrid wheat

BACKGROUND

Histone methylation usually plays important roles in plant development through post-translational regulation and may provide a new visual field for heterosis. The histone methyltransferase gene family has been identified in various plants, but its members and functions in hybrid wheat related in heterosis is poorly studied.

RESULTS

In this study, 175 histone methyltransferase (HMT) genes were identified in wheat, including 152 histone lysine methyltransferase (HKMT) genes and 23 protein arginine methyltransferase (PRMT) genes. Gene structure analysis, physicochemical properties and subcellular localization predictions of the proteins, exhibited the adequate complexity of this gene family. As an allohexaploid species, the number of the genes (seven HKMTs orthologous groups and four PRMTs orthologous groups) in wheat were about three times than those in diploids and showed certain degrees of conservation, while only a small number of subfamilies such as ASH-like and Su-(var) subfamilies have expanded their members. Transcriptome analysis showed that HMT genes were mainly expressed in the reproductive organs. Expression analysis showed that some TaHMT genes with different trends in various hybrid combinations may be regulated by lncRNAs with similar expression trends. Pearson correlation analysis of the expression of TaHMT genes and two yield traits indicated that four DEGs may participate in the yield heterosis of two-line hybrid wheat. ChIP-qPCR results showed that the histone modifications (H3K4me3, H3K36me3 and H3K9ac) enriched in promoter regions of three TaCCA1 genes which are homologous to Arabidopsis heterosis-related CCA1/LHY genes. The higher expression levels of TaCCA1 in F₁ than its parents are positive with these histone modifications. These results showed that histone modifications may play important roles in wheat heterosis.

CONCLUSIONS

Our study identified characteristics of the histone methyltransferase gene family and enhances the understanding of the evolution and function of these members in allohexaploid wheat. The causes of heterosis of two-line hybrid wheat were partially explained from the perspective of histone modifications.

Effect of Alkali and 1,4-Butanediol Contents on the Extraction of Lignin and Lignin-Based Activated Carbon

In the process of lignin extraction by the organic solvent method, the amount of alkali and the content of 1,4-butanediol are important conditions that affect lignin yield. The effects of alkali and alcohol contents on lignin recovery, removal rate, and structure were studied. In this reaction system, the removal rate of lignin increased with the increase of alkali content but decreased with the increase of alcohol content. Fourier transform infrared (FT-IR) analysis showed that the phenol hydroxyl group and the ether bond in lignin had different trends in different alkali and 1,4-butanediol environments, and four different infrared parameters in lignin had an obvious linear relationship. Gel permeation chromatography (GPC) results showed that high alkali content and high 1,4-butanediol content could lead to the fragmentation of lignin. In addition, lignin extracted from alkali-quantity factor series was selected to prepare activated carbon, CaCl₂ was selected as the activator, and its effects were studied. Results showed that in the process of extracting lignin, on the one hand, NaOH content affects the functional groups of activated carbon by affecting the aromatic structure of lignin; on the other hand, the NaOH content affects the graphitization degree and specific surface area of activated carbon by affecting the removal rate and the molecular weight of lignin.

[Clinical effects of partially de-epithelized local flaps in repairing tubercular chest wall defects]

Objective: To explore the clinical effects of partially de-epithelized local flaps in repairing tubercular chest wall defects. Methods: A retrospective observational study was conducted. From April 2010 to February 2021, twelve patients who met the inclusion criteria were admitted to the Department of Burns and Plastic Surgery of the Eighth Medical Center of PLA General Hospital, including 9 males and 3 females with age of (42±18) years. The sizes of tubercular chest wall defects of patients were ranged from 4 cm×3 cm×2 cm to 16 cm×8 cm×5 cm, which were all repaired with partial de-epithelized local flaps. The widths of flaps were equal to the widths of the defects, and the lengths of flaps were 2 cm longer than those of the defects. In one patient, the local flap was too large to close the donor site directly by suturing, so an autologous back free medium thickness skin graft was used for repair. In other patients, the collection areas of local flaps were small, and the donor areas of flaps were directly closed. The duration of operation, intraoperative bleeding, and postoperative drainage volume and indwelling time of drainage tube were observed and recorded. In two weeks after operation, the survival, color, and texture of flaps, the presence of subcutaneous hydrops and skin ulcer, and donor site healing including wound disruption, local infection, hematoma were observed. Chest X-ray, CT scan, or nuclear magnetic resonance imaging was performed in one month after operation to check whether new local hydrops and bone destruction occurred in the chest wall defects and the concomitant tuberculose focus of patients. All patients were followed up for more than 6 months to record whether the surgical incisions of the chest wall defects of the patients were complicated by hypertrophic scar, redness, swelling, and sinus. Results: In surgery, the patient had (104±18) min of operation duration, (119±53) mL of intraoperative bleeding, (134±49) mL of cumulative drainage of drainage tube, and (5.3±1.7) days of drainage tube indwelling time. In two weeks after operation, all the grafted local flaps survived, and the color and texture of flaps were similar to the surrounding normal skin. One patient had fluid leakage from the incision of chest wall defect area with the incision partially dehisced, which healed well after a phase Ⅱ operation; no wound infection, subcutaneous hydrops, or wound rupture occurred in other patients. The incisions of donor sites in all the patients healed well and no wound disruption, local infection, or hematoma occurred. One month after operation, no new bone destruction was observed in the operative region by chest imaging examination. Patients were followed up for 6 to 96 months, with one patient having wound swelling, ulceration, and sinus in the operative area of the chest wall defect in 12 months after surgery, which healed after phase Ⅱ operation; the incisions of chest wall defect wounds in other patients healed well and had no scar, redness and swelling, or sinus. Conclusions: Partially de-epithelized local flap could be used in repairing tubercular chest wall defect wounds, with the advantages of flexible flap design, minimal donor site injury, and good postoperative wound healing.

von Willebrand factor as a biomarker of clinically significant portal hypertension and severe portal hypertension: a systematic review and meta-analysis

OBJECTIVE

This meta-analysis was performed to investigate the correlation between von Willebrand factor (vWF) antigen and hepatic venous pressure gradient (HVPG) and to evaluate the diagnostic performance of vWF to detect clinically significant portal hypertension (CSPH) and severe portal hypertension (SPH).

DESIGN

Systematic review and meta-analysis.

METHODS

MEDLINE, EMBASE, Web of Science and the Cochrane Library were screened up to 5 April 2018. Studies related to the diagnostic performance of vWF to detect CSPH and/or SPH with HVPG as the reference standard were included. Study quality was assessed by using the Quality Assessment of Diagnostic Accuracy Studies scale. Two authors independently used a standardised form to extract data.

OUTCOMES

The primary outcome was the correlation coefficient between vWF and HVPG. The secondary outcome was the diagnostic performance of vWF to detect CSPH or SPH.

RESULTS

A total of six articles involving 994 patients were included in this study. Five of the included articles were used to stratify the results for the correlation coefficient, three for the diagnostic performance of CSPH and two for SPH. The pooled correlation coefficient based on the random effects model was 0.54 (95% CI 0.35 to 0.69), thus suggesting a moderate correlation between vWF and HVPG. The pooled sensitivity, specificity and area under the curve of vWF for CSPH detection were 82% (95% CI 78 to 86), 76% (95% CI 68 to 83) and 0.87 (95% CI 0.80 to 0.94), respectively. Regarding the ability of vWF to detect SPH, the pooled sensitivity and specificity were 86% (95% CI 80 to 90) and 75% (95% CI 66 to 83), respectively. These results supported the satisfactory diagnostic performance of vWF for CSPH and SPH detection.

CONCLUSIONS

vWF, as a novel biomarker, has a moderate correlation with HVPG and shows a satisfactory performance for the diagnosis of CSPH and SPH in patients with cirrhosis.

Inferring Weighted Directed Association Network from Multivariate Time Series with a Synthetic Method of Partial Symbolic Transfer Entropy Spectrum and Granger Causality

Complex network methodology is very useful for complex system explorer. However, the relationships among variables in complex system are usually not clear. Therefore, inferring association networks among variables from their observed data has been a popular research topic. We propose a synthetic method, named small-shuffle partial symbolic transfer entropy spectrum (SSPSTES), for inferring association network from multivariate time series. The method synthesizes surrogate data, partial symbolic transfer entropy (PSTE) and Granger causality. A proper threshold selection is crucial for common correlation identification methods and it is not easy for users. The proposed method can not only identify the strong correlation without selecting a threshold but also has the ability of correlation quantification, direction identification and temporal relation identification. The method can be divided into three layers, i.e. data layer, model layer and network layer. In the model layer, the method identifies all the possible pair-wise correlation. In the network layer, we introduce a filter algorithm to remove the indirect weak correlation and retain strong correlation. Finally, we build a weighted adjacency matrix, the value of each entry representing the correlation level between pair-wise variables, and then get the weighted directed association network. Two numerical simulated data from linear system and nonlinear system are illustrated to show the steps and performance of the proposed approach. The ability of the proposed method is approved by an application finally.