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排序方式: 共有662条查询结果,搜索用时 0 毫秒
111.
Alejandro Israel Bautista-Castillo Luis Abraham Sánchez-Gaspariano Victor Rodolfo González-Díaz Carlos Muñiz-Montero Jose Miguel Rócha Pérez Alejandro Díaz-Sánchez 《Analog Integrated Circuits and Signal Processing》2017,90(2):383-388
The design and simulation of a 2nd harmonic based upconverter is introduced. With the proposed upconverter, it is possible to reach a good noise figure with power and area reduction. The design of the circuit was made with the UMC \(0.18\,\upmu \hbox {m}\) Mixed Mode/RF CMOS technology. However, the design methodology can be extended to a different CMOS process. According to the performance exhibited by the purposed mixer, it may be useful in wideband short-range communication technologies, such as certified wireless USB. 相似文献
112.
Soh JL Wang F Boersen N Pinal R Peck GE Carvajal MT Cheney J Valthorsson H Pazdan J 《Drug development and industrial pharmacy》2008,34(10):1022-1035
This article aimed to model the effects of raw material properties and roller compactor operating parameters (OPs) on the properties of roller compacted ribbons and granules with the aid of principal component analysis (PCA) and partial least squares (PLS) projection. A database of raw material properties was established through extensive physical and mechanical characterization of several microcrystalline cellulose (MCC) and lactose grades and their blends. A design of experiment (DoE) was used for ribbon production. PLS models constructed with only OP-modeled roller compaction (RC) responded poorly. Inclusion of raw material properties markedly improved the goodness of fit (R(2) = .897) and model predictability (Q(2) = 0.72). 相似文献
113.
Kamat PC Roller CB Namjou K Jeffers JD Faramarzalian A Salas R McCann PJ 《Applied optics》2007,46(19):3969-3975
A high-resolution liquid-nitrogen-free mid-infrared tunable diode laser absorption spectroscopy (TDLAS) system was used to perform real-time measurement of acetaldehyde concentrations in human exhaled breath following ingestion of an alcoholic beverage. Acetaldehyde absorption features were measured near 5.79 mum (1727 cm(-1)) using a IV-VI semiconductor laser, a 100 m long path optical gas cell, and second- harmonic detection coupled with wavelength modulation. Acetaldehyde levels were measured with a minimum detection limit of 80 ppb for 5 s integration time. The variations in exhaled acetaldehyde levels over time were analyzed prior to and following ingestion of two different amounts of white wine. A method to calibrate acetaldehyde measurements internally using water vapor absorption lines was investigated to eliminate the need for system calibration with gas standards. The potential of a TDLAS system to be used as a noninvasive clinical tool for measurements of large volatile compounds with possible applications in cancer detection is demonstrated. 相似文献
114.
We examined the in vivo contribution of insulin, T090137 (T09), agonist of liver X receptor (LXR), fenofibrate, agonist of
peroxisome proliferator activated receptor (PPAR-α) and sterol regulatory element binding protein-1c (SREBP-1c) on the unsaturated
fatty acid synthesis controlled by Δ6 and Δ5 desaturases, compared with the effects on stearoylcoenzyme A desaturase-1. When
possible they were checked at three levels: messenger RNA (mRNA), desaturase protein and enzymatic activity. In control rats,
only fenofibrate increased the insulinemia that was maintained by the simultaneous administration of T09, but this increase
has no specific effect on desaturase activity. T09 enhanced SREBP-1 in control animals and the mRNAs and activity of the three
desaturases in control and type-1 diabetic rats, demonstrating a LXR/SREBP-1-mediated activation independent of insulin. However,
simultaneous administration of insulin and T09 to diabetic rats led to a several-fold increase of the mRNAs of the desaturases,
suggesting a strong synergic effect between insulin and LXR/retinoic X receptor (RXR). Moreover, this demonstrates the existence
of an interaction between unsaturated fatty acids and cholesterol metabolism performed by the insulin/SREBP-1c system and
LXR/RXR. PPAR-α also increased the expression and activity of the three desaturases independently of the insulinemia since
it was equivalently evoked in streptozotocin diabetic rats. Besides, PPAR-α increased the palmitoylcoenzyme A elongase, evidencing
a dual regulation in the fatty acid biosynthesis at the level of desaturases and elongases. The simultaneous administration
of fenofibrate and T09 did not show additive effects on the mRNA expression and activity of the desaturases. Therefore, the
results indicate a necessary sophisticated interaction of all these factors to produce the physiological effects. 相似文献
115.
Otero R Ecija D Fernandez G Gallego JM Sanchez L Martín N Miranda R 《Nano letters》2007,7(9):2602-2607
A precise control of the nanometer-scale morphology in systems containing mixtures of donor/acceptor molecules is a key factor to improve the efficiency of organic photovoltaic devices. Here we report on a scanning tunneling microscopy study of the first stages of growth of 2-[9-(1,3-dithiol-2-ylidene)anthracen-10(9H)-ylidene]-1,3-dithiole, as electron donor, and phenyl-C61-butyric acid methyl ester, as electron acceptor, on a Au(111) substrate under ultrahigh vacuum conditions. Due to differences in bonding strength with the substrate and different interactions with the Au(111) herringbone surface reconstruction, mixed thin films spontaneously segregate into a lateral superlattice of interdigitated nanoscale stripes with a characteristic width of about 10-20 nm, a morphology that has been predicted to optimize the efficiency of organic solar cells. 相似文献
116.
117.
Bárbara Biduski Jarine Amaral do Evangelho Karina Oliveira Lima Shanise Lisie de Mello El Halal Elessandra da Rosa Zavareze Alvaro Renato Guerra Dias Vânia Zanella Pinto 《Starch - St?rke》2024,76(1-2):2200209
Using non-conventional starch can benefit the industry since it can present different properties. It also can lead to new properties upon physical modification, which improves its derivate film properties. Therefore, the aim of this work is to evaluate the heat–moisture treatment (HMT) on pinhão starch and its effectiveness in film properties. After isolation using water as a solvent, the pinhão starch is treated by HMT for 16 h at 110 °C. Native and HMTed starches are used to produce biodegradable films. Pinhão starch and starch films chemical and physical properties are properly characterized. The HMT causes some changes in short-range ordered structures, reduces the relative crystallinity, and shifts the pinhão starch from C-type to A-type. Also, HMT decreases the peak viscosity and the breakdown, and improves thermal stability. These starch changes upon HMT reduces water vapor permeability, increases tensile strength, and elongation at the break of pinhão starch films. Desirable changes in starch and film properties are achieved by physically modifying pinhão starch using HMT, which is a promising alternative to chemical modifications. 相似文献
118.
Camila Morais Melo Thiago Vidotto Luiz Paulo Chaves William Lautert-Dutra Rodolfo Borges dos Reis Jeremy Andrew Squire 《International journal of molecular sciences》2021,22(17)
Immunotherapy has improved patient survival in many types of cancer, but for prostate cancer, initial results with immunotherapy have been disappointing. Prostate cancer is considered an immunologically excluded or cold tumor, unable to generate an effective T-cell response against cancer cells. However, a small but significant percentage of patients do respond to immunotherapy, suggesting that some specific molecular subtypes of this tumor may have a better response to checkpoint inhibitors. Recent findings suggest that, in addition to their function as cancer genes, somatic mutations of PTEN, TP53, RB1, CDK12, and DNA repair, or specific activation of regulatory pathways, such as ETS or MYC, may also facilitate immune evasion of the host response against cancer. This review presents an update of recent discoveries about the role that the common somatic mutations can play in changing the tumor microenvironment and immune response against prostate cancer. We describe how detailed molecular genetic analyses of the tumor microenvironment of prostate cancer using mouse models and human tumors are providing new insights into the cell types and pathways mediating immune responses. These analyses are helping researchers to design drug combinations that are more likely to target the molecular and immunological pathways that underlie treatment failure. 相似文献
119.
Masotti L Biagi E Scabia M Acquafresca A Facchini R Ricci A Bini D 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2006,53(10):1783-1795
Fast echographic multiparameter multi-image novel apparatus (FEMMINA), is a hardware and software platform dedicated to ultrasonic signal and image processing. FEMMINA is able to operate with sequences of radiofrequency (RF) frames. Its architecture is designed to be modular, expandable, and aimed at implementing different ultrasonic investigation techniques. The first experimental characteristic of this system is in its capability to operate in real time with ultrasonic RF signals, starting from acquisition up to processing, storage, and visualization. The second characteristic is the user-system interactivity that allows one to modify the operation appropriately while observing results. Currently, FEMMINA works in both typical experimental situations to study novel investigation techniques and clinical field to validate the proposed methods in different human districts. 相似文献
120.
Jifeng Liu Rodolfo Camacho-AguileraJonathan T. Bessette Xiaochen SunXiaoxin Wang Yan CaiLionel C. Kimerling Jurgen Michel 《Thin solid films》2012,520(8):3354-3360
Electronic-photonic synergy has become an increasingly clear solution to enhance the bandwidth and improve the energy efficiency of information systems. Monolithic integration of optoelectronic devices is the ideal solution for large-scale electronic-photonic synergy. Due to its pseudo-direct gap behavior in optoelectronic properties and compatibility with Si electronics, epitaxial Ge-on-Si has become an attractive solution for monolithic optoelectronics. In this paper we will review recent progress in Ge-on-Si optoelectronics, including photodetectors, electroabsorption modulators, and lasers. The performance of these devices has been enhanced by band-engineering such as tensile strain and n-type doping, which transforms Ge towards a direct gap material. Selective growth reduces defect density and facilitates monolithic integration at the same time. Ge-on-Si photodetectors have approached or exceeded the performance of their III-V counterparts, with bandwidth-efficiency product > 30 GHz for p-i-n photodiodes and bandwidth-gain product > 340 GHz for avalanche photodiodes. Enhanced Franz-Keldysh effect in tensile-strained Ge offers ultralow energy photonic modulation with < 30 fJ/bit energy consumption and > 100 GHz intrinsic bandwidth. Room temperature optically-pumped lasing as well as electroluminescence has also been achieved from the direct gap transition of band-engineered Ge-on-Si waveguides. These results indicate that band-engineered Ge-on-Si is promising to achieve monolithic active optoelectronic devices on a Si platform. 相似文献