A Compact High-Isolation Four-Element MIMO Antenna with Asymptote-Shaped Structure.

The demand for high-speed wireless communication systems has led to the development of ultrawide-band (UWB) antennas with a compact size and high performance. In this paper, we propose a novel four-port multiple-input multiple-output (MIMO) antenna with an asymptote-shaped structure that overcomes the limitations of existing designs for UWB applications. The antenna elements are placed orthogonally to each other for polarization diversity, and each element features a stepped rectangular patch with a tapered microstrip feedline. The unique structure of the antenna significantly reduces its dimensions to 42 × 42 mm2 (0.43λ×0.43λ@ 3.09GHz), making it highly desirable for use in small wireless devices. To further enhance the antenna's performance, we use two parasitic tapes on the ground plane at the back as decoupling structures between adjacent elements. The tapes are designed in a windmill shape and a rotating extended cross shape, respectively, to further improve the isolation. We fabricated and measured the proposed antenna design on a single-layer substrate (FR4) with a dielectric constant of 4.4 and a thickness of 1 mm. The measured results show that the impedance bandwidth of the antenna is 3.09-12 GHz, with an isolation of -16.4 dB, an envelope correlation coefficient (ECC) of 0.02, a diversity gain (DG) of 9.991 dB, an average total effective reflection coefficient (TARC) of -20 dB, an overall group delay value less than 1.4 ns, and a peak gain of 5.1 dBi. Although there may be some antennas that have better performance in one or two specific aspects, our proposed antenna has an excellent trade-off among all the antenna characteristics including bandwidth, size, and isolation. The proposed antenna also exhibits good quasi-omnidirectional radiation properties, making it well-suited for a range of emerging UWB-MIMO communication systems, particularly in small wireless devices. In summary, the compact size and ultrawide-band capabilities of the proposed MIMO antenna design, coupled with its improved performance compared to other recent UWB-MIMO designs, make it a promising candidate for 5G and next-generation wireless communication systems.

Axial p-n junction and space charge limited current in single GaN nanowire.

The electrical characterizations of individual basic GaN nanostructures, such as axial nanowire (NW) p-n junctions, are becoming indispensable and crucial for the fully controlled realization of GaN NW based devices. In this study, electron beam induced current (EBIC) measurements were performed on two single axial GaN p-n junction NWs grown by plasma-assisted molecular beam epitaxy. I-V characteristics revealed that both ohmic and space charge limited current (SCLC) regimes occur in GaN p-n junction NW. Thanks to an improved contact process, both the electric field induced by the p-n junction and the SCLC in the p-part of GaN NW were disclosed and delineated by EBIC signals under different biases. Analyzing the EBIC profiles in the vicinity of the p-n junction under 0 V and reverse bias, we deduced a depletion width in the range of 116-125 nm. Following our previous work, the acceptor N a doping level was estimated to be 2-3 × 1017 at cm-3 assuming a donor level N d of 2-3 × 1018 at cm-3. The hole diffusion length in n-GaN was determined to be 75 nm for NW #1 and 43 nm for NW #2, demonstrating a low surface recombination velocity at the m-plane facet of n-GaN NW. Under forward bias, EBIC imaging visualized the electric field induced by the SCLC close to p-side contact, in agreement with unusual SCLC previously reported in GaN NWs.

[Comparative analysis for mental patients' life quality between developed and developing regions].

OBJECTIVE: To explore the differences, causes and countermeasures for mental patients' life quality between developed and developing regions.
 Methods: Based on the Quality of Life Questionnaire for Psychiatric Patients (QOL-P) and adopting convenient random sampling method, a total of 340 mental patients in Shanghai and Guangxi were investigated, and the data were analyzed by methods of Paired Design Crosstabulation Data hypothesis test, multivariate logistic regression, and independent sample Kruskal-Wallis test. The differences in patients' life quality in the 2 regions and the influential factors were evaluated.
 Results: There were high consistency and correlation in the total scores of self-evaluation items G (self overall evaluation of life quality by patient) between the 2 regions. Region and gender significantly affected mental patients' life quality in the basic demography characteristics in the 2 regions. The differences between total scores of 4 independent samples grouped by region and sex were significant (P<0.01). The male and femal patients in Guangxi in the dimensions of physiology, psychology, society and symptom were better than those in Shanghai (P<0.01). There was certain homoplasy between the patients from Shanghai and those from Guangxi in terms of the most prominent matters that affect the mental patients' life quality, with the former being affected more seriously than the latter.
 Conclusion: To a certain extent, the mental patients' life quality in the developing region (Guangxi) is better than that in the developed region (Shanghai).

Si Donor Incorporation in GaN Nanowires.

With increasing interest in GaN based devices, the control and evaluation of doping are becoming more and more important. We have studied the structural and electrical properties of a series of Si-doped GaN nanowires (NWs) grown by molecular beam epitaxy (MBE) with a typical dimension of 2-3 µm in length and 20-200 nm in radius. In particular, high resolution energy dispersive X-ray spectroscopy (EDX) has illustrated a higher Si incorporation in NWs than that in two-dimensional (2D) layers and Si segregation at the edge of the NW with the highest doping. Moreover, direct transport measurements on single NWs have shown a controlled doping with resistivity from 10(2) to 10(-3) Ω·cm, and a carrier concentration from 10(17) to 10(20) cm(-3). Field effect transistor (FET) measurements combined with finite element simulation by NextNano(3) software have put in evidence the high mobility of carriers in the nonintentionally doped (NID) NWs.

The Diagnostic Value of Serum GDF15 and hs-CTnT in Elderly Patients with Acute Myocardial Infarction.

Objective: To analyze the diagnostic value of serum growth differentiation factor 15 (GDFl5) and high-sensitivity troponin T (hs-cTnT) in elderly acute myocardial infarction (AMI). Methods: A retrospective analysis of 165 patients with acute chest pain admitted to the Department of Cardiology in our hospital from January to December 2020, Among them, 76 AMI patients (AMI group), 89 non-AMI patients (non-AMI group), and 80 healthy people were selected as the control group during the same period. Compare the three groups of serum GDF15, hs-CTnT levels, and left ventricular ejection fraction (LVEF) parallel correlation analysis, and draw the receiver operating curve (ROC) of serum GDF15 and hs-CTnT levels to diagnose AMI. Results: The serum GDF15 and hs-CTnT levels of the AMI group were significantly higher than those of the non-AMI group and the control group, and the difference was statistically significant (p < 0.01). The LVEF was significantly lower than the non-AMI group and the control group, whose difference was statistically significant (p < 0.01). Among them, the indicators of the non-AMI group were both higher and lower than the control group, and the difference was statistically significant (p < 0.01). Serum GDF15 and hs-CTnT levels of AMI patients increased with the increase of NYHA grade, among which grade IV group was significantly higher than grade I∼II group and grade III group (P < 0.01), and grade III group was significantly higher than grade I∼II Group (p < 0.01). Pearson correlation analysis showed that GDF15 and hs-CTnT levels of AMI patients were significantly negatively correlated with LVEF (r = -0.584, -0.612, - < 0.01). The ROC curve showed that GDF15 had a high specificity (93.75%) and hs-CTnT has a high sensitivity (90.67%). The area under the curve for diagnosing AMI is > 0.7 (0.895, 0.948). The sensitivity of the combined detection and the specificity are higher than that of individual detection. Conclusion: Serum GDF15 and hs-CTnT are highly expressed in elderly patients with AMI. The combined detection of the two can improve the efficiency of AMI diagnosis. GDF15 can be used as a new biomarker for AMI diagnosis and disease monitoring.

Functional characterization of human umbilical cord-derived mesenchymal stem cells for treatment of systolic heart failure.

Congestive heart failure (HF) is a leading cause of morbidity and mortality worldwide. Although advances in medical therapy, mechanical support and heart transplantation have been made, almost half of all patients with HF succumb to the disease within five years of the initial diagnosis. Therefore, treatment methods need to be identified to restore the structure and function of cardiac muscle. Three patients with HF caused by ischemic cardiomyopathy received human umbilical cord-derived mesenchymal stem cell (HUC-MSC) intravenous infusion were included in the present study. Two patients demonstrated a 65.1% increase in left ventricular ejection fraction (LVEF) at the end of 3 months, which was maintained increasing 47.8% at the end of 12 months post-HUC-MSC intravenous infusion. LVEF of patient 1 decreased slowly in the observation period. This LVEF improvement was associated with significant improvements in the clinical parameters of the New York Heart Association class, and six-minute walk test in the coupled time. The third patient showed significant improvement in the six-minute walk test at the end of 12 months, while the other parameters did not change obviously. There were no severe adverse events during and post-HUC-MSC transplantation. During follow-up, no other immunosuppressive drugs were used. In conclusion, HUC-MSC therapy is a reasonable salvage treatment in HF. Future large-scale randomized clinical trials are likely to be designed to elucidate the efficacy of the HUC-MSC transplantation therapy on HF.