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In order to improve the electrical and frequency characteristics of SiGe heterojunction bipolar transistors (HBTs), a novel structure of SOI SiGe heterojunction bipolar transistor is designed in this work. Compared with traditional SOI SiGe HBT, the proposed device structure has smaller window widths of emitter and collector areas. Under the act of additional uniaxial stress induced by Si0.85Ge0.15, all the collector region, base region and emitter region are strained, which is beneficial to improve the performance of SiGe HBTs. Employing the SILVACOⓇ TCAD tools, the numerical simulation results show that the maximum current gain βmax, the Earley voltage VA are achieved for 1062 and 186 V, respectively, the product of β and VA, i.e., β ×VA, is 1.975 × 105 V and, the peak cutoff frequency fT is 419 GHz when the Ge component in the base has configured to be a trapezoidal distribution. The proposed SOI SiGe HBT architecture has a 52.9% improvement in cutoff frequency fT compared to the conventional SOI SiGe HBTs.

Macrophages play pivotal roles in immunity, hematopoiesis, and tissue homeostasis. In mammals, macrophages have been shown to originate from yolk-sac-derived erythro-myeloid progenitors and aorta-gonad-mesonephros (AGM)-derived hematopoietic stem cells. However, whether macrophages can arise from other embryonic sites remains unclear. Here, using single-cell RNA sequencing, we profile the transcriptional landscape of mouse fetal placental hematopoiesis. We uncover and experimentally validate that a CD44+ subpopulation of placental endothelial cells (ECs) exhibits hemogenic potential. Importantly, lineage tracing using the newly generated Hoxa13 reporter line shows that Hoxa13-labeled ECs can produce placental macrophages, named Hofbauer cell (HBC)-like cells. Furthermore, we identify two subtypes of HBC-like cells, and cell-cell interaction analysis identifies their potential roles in angiogenesis and antigen presentation, separately. Our study provides a comprehensive understanding of placental hematopoiesis and highlights the placenta as a source of macrophages, which has important implications for both basic and translational research.

A novel SiGe HBT architecture is designed by introducing the embedded Si 1−y Ge y stress raiser into the collector. In the proposed HBT structure, the emission region, the base region and the collector region are all subjected to stress, so as to enhance the characteristic frequency. The effect of embedded Si 1−y Ge y stress raiser on the frequency performance with different Ge fractions are simulated and analyzed by employing SILVACO TCAD tools. The simulation results show that the high frequency performance of the device can be significantly improved by applying an additional uniaxial stress in the collector. Taking the uniform SiGe base case with the Ge fraction of 0.25 as an example, when y = 0.15, the peak values of fT and fmax reach about 507.7 GHz and 730.7 GHz, respectively. Compared with the SiGe HBT without any additional stress in the collector, f T and f max are respectively increased by 29.1% and 71.5%. When y = 0.1, the proposed device has the best frequency characteristics with the maximum of f T ×f max , and the Johnson’s limit (f T ×BV CEO ) is increased by about 26%.

Shilin Xiao, Xian Yu, Liang Zhang, Ya Zhang, Weijie Fan, Tao Sun, Chunyu Zhou, Yun Liu, Yiding Liu, Mingfu Gong, Dong Zhang Department of Radiology, Xinqiao Hospital, Army Medical University, Chongqing, People’s Republic of ChinaCorrespondence: Mingfu Gong; Dong ZhangDepartment of Radiology, Xinqiao Hospital, Army Medical University, Xinqiao Street, Shapingba District, Chongqing, People’s Republic of ChinaTel +86 23 6876 3843Fax +86 23 6875 5306Email hummer198625@163.com; hszhangd@163.comBackground: Beyond magnetic resonance imaging (MRI), which has been widely used clinically, molecular MRI (mMRI) can further provide qualitative and quantitative information at the cellular and molecular levels. However, the diagnostic accuracy may not be satisfactory via single-contrast mMRI due to some interferences in vivo. T1/T2 dual-contrast MRI using the same contrast agent (CA) could significantly improve the detection accuracy. Therefore, in this study, we fabricated poly(ethylene glycol) (PEG)-coated, manganese-doped iron oxide nanocomposites (Mn-IONPs@PEG) as T1/T2 dual-contrast CA, and evaluated its feasibility of T1/T2 dual-contrast MRI in vitro and in vivo.Methods: Mn-IONPs were prepared by the thermal decomposition of iron-eruciate and manganese-oleate complexes and were coated with 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-N-(methoxy[polyethylene glycol]-2000) (DSPE-PEG 2000). The physicochemical properties and cytotoxicity of the Mn-IONPs were fully characterized, followed by MRI in vitro and in vivo.Results: Ultrasmall 3 nm-sized nanoparticles were successfully prepared and were identified using transmission electron microscopy (TEM), high-resolution TEM, and X-ray diffraction. After coating with DSPE-PEG, the Mn-IONPs@PEG displayed excellent hydrophilicity and good biocompatibility. Due to the manganese-doping and PEG coating, the Mn-IONPs@PEG showed good relaxivity in vitro. Especially, the Mn-IONPs@PEG coated with DSPE-PEG following a mass ratio to Mn-IONPs of 1:20 showed harmonious longitudinal relaxivity (r1 = 7.1 mM−1s−1) and transversal relaxivity (r2 = 120.9 mM−1s−1), making it a better candidate for T1/T2 dual-contrast mMRI. After administrated via a caudal vein, the Mn-IONPs@PEG can induce significant enhancement in both T1-weighted and T2-weighted MR images and the time at 10 mins after injection was regarded as a suitable time for imaging because both the T1 and T2 enhancement were optimum at that time.Conclusion: The obtained Mn-IONPs@PEG exhibited good r1 and r2 and was a reasonable candidate for T1/T2 dual-contrast mMRI.Keywords: magnetic resonance imaging, manganese-doped iron oxide nanoparticles, T1/T2 dual-contrast, DSPE-PEG coating, high relaxivity

The pure electric vehicle can be driven and regenerative braked by motor, so the development of single-pedal function which is realised by motor torque and evaluation on drivability of electric vehicle is researched in this paper. Driver can launch, accelerate, brake even park only by operating accelerator pedal. Single-pedal function is researched based on PID and Co-simulation using Matlab/Simulink and Carsim. Evaluation standards and indexes about drivability of electric vehicle with sing-pedal are developed which is implemented on a real vehicle. The research can support the optimization and development of single-pedal function for electric vehicle.

Utilizing a mutant of neomycin-producing Streptomyces fradiae mutagenized with neutron radiation, biotransformation of neomycin into modified compounds was studied. The biotransformation products were isolated by ion exchange chromatography and monitored by thin layer chromatography bioautography (TLCB). Antibacterial activity of biotransformation products against ten species of bacteria including four plant pathogens was tested qualitatively by TLCB and detected quantitatively by Oxford cup method. The minimal inhibitory concentration (MIC) of biotransformation products was tested by agar diffusion method. Three isolated transformation products had obvious antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Proteus vulgaris and Pseudomonas solanacarum. At the concentration of 50 μg/ml, the transformation product X had a similar antibacterial effect with neomycin but the transformation product Y and Z showed a decreased effect compared to neomycin except for P. vulgaris and P. solanacarum. However, the results from MIC analysis demonstrated that only the transformation product X maintained the same inhibitory effect with neomycin.Key words: Neomycin, biotransformation, Streptomyces fradiae, mutant, neutron radiation.

The technique of Web application based on the feature code database can only defense the general and known attacks, when the attacks are varietal or not defined by feature, it's protective effect is poor, and may even lead to the problem of high false positives and false negatives. The proactive defense technique of web application based on HttpModule is put forward in this thesis. It can forecast the attacks in advance and defense without analyzing samples or updating feature code database. The experimental results show that this technique has a good performance of the proactive defensive.