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1.
Zolper J.C. Shenvin M.E. Baca A.G. Shul R.J. Klem J.F. Hietala V.M. 《Electron Device Letters, IEEE》1994,15(12):493-495
C ion implantation has been employed, for the first time, to form the buried p-layer in GaAs, self-aligned, ion implanted JFETs. Comparable DC performance was seen for JFETs with C or Mg implants; however, C-backside JFETs showed superior high-frequency performance. High dose C-backside devices had a ft of 28.3 GHz and a fmax of 43.2 GHz for a 0.5 μm gate length that were 28% and 46% higher, respectively, than comparable Mg-implanted JFETs. This enhancement is a result of the lower Cgs in the C-backside device resulting from he inherently low activation of the implanted C below the channel while the C still effectively compensated the tail of the Si-channel implant. This approach relaxes the trade-off between optimizing the DC and the AC performance for the buried p-implant in GaAs JFETs and MESFET's 相似文献
2.
Franziska Dengler Sofia Sova Antti M. Salo Joni M. Mki Peppi Koivunen Johanna Myllyharju 《International journal of molecular sciences》2021,22(8)
The HIF prolyl 4-hydroxylases (HIF-P4H) control hypoxia-inducible factor (HIF), a powerful mechanism regulating cellular adaptation to decreased oxygenation. The gastrointestinal epithelium subsists in “physiological hypoxia” and should therefore have an especially well-designed control over this adaptation. Thus, we assessed the absolute mRNA expression levels of the HIF pathway components, Hif1a, HIF2a, Hif-p4h-1, 2 and 3 and factor inhibiting HIF (Fih1) in murine jejunum, caecum and colon epithelium using droplet digital PCR. We found a higher expression of all these genes towards the distal end of the gastrointestinal tract. We detected mRNA for Hif-p4h-1, 2 and 3 in all parts of the gastrointestinal tract. Hif-p4h-2 had significantly higher expression levels compared to Hif-p4h-1 and 3 in colon and caecum epithelium. To test the roles each HIF-P4H isoform plays in the gut epithelium, we measured the gene expression of classical HIF target genes in Hif-p4h-1−/−, Hif-p4h-2 hypomorph and Hif-p4h-3−/− mice. Only Hif-p4h-2 hypomorphism led to an upregulation of HIF target genes, confirming a predominant role of HIF-P4H-2. However, the abundance of Hif-p4h-1 and 3 expression in the gastrointestinal epithelium implies that these isoforms may have specific functions as well. Thus, the development of selective inhibitors might be useful for diverging therapeutic needs. 相似文献
3.
We introduce a machine learning-based classifier that identifies free radio channels for cognitive radio. The architecture is designed for nanoscale implementation, under nanoscale implementation constraints; we do not describe all physical details but believe future physical implementation to be feasible. The system uses analog computation and consists of cyclostationary feature extraction and a radial basis function network for classification. We describe a model for nanoscale faults in the system, and simulate experimental performance and fault tolerance in recognizing WLAN signals, under different levels of noise and computational errors. The system performs well under expected non-ideal manufacturing and operating conditions. 相似文献
4.
Andressa V. B. Nogueira Marjan Nokhbehsaim Anna Damanaki Sigrun Eick Svenja Beisel-Memmert Christian Kirschneck Agnes Schrder Thamiris Cirelli Natalia D. P. Leguizamn Joni A. Cirelli James Deschner 《International journal of molecular sciences》2022,23(6)
The effect of bacterial infection on the expression of growth hormone secretagogue receptor (GHS-R) was investigated in periodontal cells and tissues, and the actions of ghrelin were evaluated. GHS-R was assessed in periodontal tissues of rats with and without periodontitis. Human gingival fibroblasts (HGFs) were exposed to Fusobacterium nucleatum in the presence and absence of ghrelin. GHS-R expression was determined by real-time PCR and immunocytochemistry. Furthermore, wound healing, cell viability, proliferation, and migration were evaluated. GHS-R expression was significantly higher at periodontitis sites as compared to healthy sites in rat tissues. F. nucleatum significantly increased the GHS-R expression and protein level in HGFs. Moreover, ghrelin significantly abrogated the stimulatory effects of F. nucleatum on CCL2 and IL-6 expressions in HGFs and did not affect cell viability and proliferation significantly. Ghrelin stimulated while F. nucleatum decreased wound closure, probably due to reduced cell migration. Our results show original evidence that bacterial infection upregulates GHS-R in rat periodontal tissues and HGFs. Moreover, our study shows that ghrelin inhibited the proinflammatory actions of F. nucleatum on HGFs without interfering with cell viability and proliferation, suggesting that ghrelin and its receptor may act as a protective molecule during bacterial infection on periodontal cells. 相似文献
5.
Joni Agustian Azlina Harun Kamaruddin Subhash Bhatia 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(8):1032-1048
A two separate phase‐enzymatic membrane reactor is an attractive process since it has a large interfacial area and exchange surfaces, simultaneous reaction and separation and other benefits. Many factors influence its successful operation, and these include characteristics of the enzyme, membrane, circulating fluids and reactor operations. Although the operating conditions are the main factor, other factors must be considered before, during or after its application. At the initial stage of reactor development, the solubility of substrates and products, type of operation, membrane material and size, enzyme preparation and loading procedure, and cleanliness of the recirculated fluids should be specified. The immobilization site, reactor arrangement, dissolved or no‐solvent operation, classic or emulsion operation and immobilized or suspended enzyme(s) are determined later. Some factors still need further studies. Utilization of the technology is described for use from multigram‐ to plant‐scale capacity to process racemic and achiral compounds. The racemates were resolved primarily by kinetic resolution, but dynamic kinetic resolution has been exploited. The technology focused on hydrolytic reactions, but esterification processes were also exploited. Copyright © 2011 Society of Chemical Industry 相似文献
6.
In spite of considerable research about the poor retention rate of undergraduate engineering students, we still have an inadequate understanding of the factors that affect students' decisions to remain in engineering programs and their ability to perform well enough to be retained. Although continued study is needed of external factors such as curricular requirements, admissions criteria, and test scores, we also need to know much more about the relationships between curricular experiences and students' learning styles, habits, and attitudes. The work presented in this paper was designed to enhance educators' understanding of the factors that underlie the concern about student retention in engineering. By observing 1,000 engineering students during their first three years in college, the research team generated a large database on the students' academic and non‐academic characteristics as well as their successes and failures. The traits discovered not only support many findings from previous studies but also reveal some new relationships that could prove essential to designing an educational environment that will prepare engineers for success in the future. 相似文献
7.
Rheological properties of aqueous solutions and hydrogels formed by an amphiphilic star block copolymer, poly(acrylic acid)-block-polystyrene (PAA54-b-PS6)4, were investigated as a function of the polymer concentration (Cp), temperature, and added salt concentration. The water-soluble polymer synthesised by atom transfer radical polymerization (ATRP) was found to form hydrogels at room temperature at polymer concentrations, Cp, over 22 g/L due to the interpolymer hydrophobic association of the PS blocks. Increasing Cp leads to stronger elastic networks at room temperature that show a gel-to-solution transition with increasing temperature. Increase of ionic strength decreases the moduli compared with the pure hydrogel but did not affect the gel-sol transition temperature significantly. Small-angle X-ray experiments showed two distinct scattering correlation peaks for samples above the gelling Cp, which indicates the aggregates formed due to hydrophobic association. Upon heating the intensity of the scattering correlation peaks was found to decrease indicating the loss of the network structure due to thermal motion. 相似文献
8.
Susan L. Hietala Douglas M. Smith C. Jeffrey Brinker Alan J. Hurd Altaf H. Carim Neal Dando 《Journal of the American Ceramic Society》1990,73(10):2815-2821
This paper compares the structure ofAl2 O3 -SiO2 xerogels prepared with Al2 O3 contents ranging from 21 to 75 wt% (13 to 64 mol%). The 47 wt% Al2 O3 xerogel (Al/Si ≅ 1) exhibits anomalously low surface area (≅1 m2 /g) and skeletal density compared with other Al2 O3 -Si2 compositions. Based on the results of nitrogen adsorption/condensation, helium displacement, high-resolution transmission electron microscopy (HRTEM), small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS), we attribute the low surface area and skeletal density (density of the solid phase which is inaccessable to helium) to the formation of closed micropores, whereas the higher surface area materials exhibit a slightly coarser texture comprising open pores with radii of ≅1 nm. X-ray diffraction (XRD) and 29 SI and 27 Al magic-angle spinning nuclear magnetic resonance (MASNMR) indicate no anomalous behavior in the 47% sample on molecular length scales. HRTEM indicates the presence of a small fraction of crystallites which is supported by the SAXS results, but it is unknown if this crystallinity is related to low surface area. Low-field 1 H NMR spin-lattice relaxation measurements show that the physical structure of all of the 'wet' gels is similar implying that pore closure occurs during drying. Consistent with this idea, gel surface area and density increased significantly when the pore fluid (water) was replaced with a lower surface tension fluid (formamide, dioxane, ethanol. water/surfactant). 相似文献
9.
We present measurements and simulations of a transmission-line network that has been designed for cloaking applications in the microwave region. Here the network is not used for cloaking but for channelling electromagnetic fields through an electrically dense array of metal objects, which alone is basically impenetrable to the impinging electromagnetic radiation. With the designed transmission-line network the waves emitted by a source placed in an air-filled waveguide are coupled into the network and guided through the array of metallic objects. Our goal is to illustrate the simple manufacturing, assembly, and the general feasibility of cloaking devices based on the transmission-line approach. Most importantly, we demonstrate both with measurements and with numerical simulations the excellent coupling of waves between the network and the surrounding medium. 相似文献
10.
Joni Polili Lie Boon Poh Ng Chong Meng Samson See 《International Journal of Communication Systems》2010,23(12):1537-1553
In this paper, we propose a direction finding (DF) receiver for ultra wideband impulse radio (UWB‐IR) signal in a realistic multipath environment. The receiver uses an array of antenna, where each antenna is connected to a proposed propagation‐delay estimation structure. The advantage of the proposed structure is that it outputs a trapezoidal signal whose amplitude reflects the propagation delay and thus relaxes the sampling rate requirement of the analog‐to‐digital‐converter (ADC). The angle‐of‐arrival (AOA) is estimated from the vector of propagation delays measured with respect to reference antenna. Because these estimated delays contain outliers, we propose a simple AOA estimation algorithm based on minimum fractional‐distance search. Experimental results based on simulation show that the proposed DF receiver achieves better performance compared with the minimum ?1‐ and ?2‐based (least‐squares based) distance search. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献