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91.
The authors demonstrate improved performance in tunable distributed-Bragg-reflector lasers using GaInAs/GaInAsP multiple-quantum-well active layers. They observe linewidths as low as 1.9 MHz, differential quantum efficiencies as large as 33%/front facet at 1.5 μm, and rapid electronic access to all frequencies throughout a 1000 GHz range 相似文献
92.
The potential for mineral scaling that may limit the generation of new potable water resources by reverse osmosis (RO), from inland brackish water of high gypsum scaling propensity, was experimentally explored via flux decline measurements and real-time RO membrane surface imaging. Antagonistic gypsum and calcium carbonate scaling kinetics were demonstrated for high-sulfate brackish water desalting. RO scaling studies with brackish water from the California San Joaquin Valley (approximately 10 000 mg/L total dissolved solids) revealed that membrane gypsum scaling was increasingly retarded with rising bicarbonate concentrations. Crystal growth rate, fractional membrane scale coverage, and flux decline decreased by up to about 63, 78, and 73%, respectively, as the bicarbonate concentration increased, at the membrane surface, from < 0.01 to 7.81 mM, for a gypsum saturation index of 2. Inhibition of gypsum crystal growth was attributed to bicarbonate adsorption onto the crystal surfaces, and CaCO3 scaling was undetected even up to a calcite saturation index of approximately 16. Given the suppression of gypsum scaling by bicarbonate, it is essential to considerthis effect in the conventional practice of pH adjustment to suppress CaCO3 scaling. The present results suggest that antagonistic and synergistic mineral crystallization kinetics effects are important for optimizing scale-control strategies (e.g., acid and antiscalants addition to the RO feed). 相似文献
93.
A. I. Lyudvinskii L. B. Romanovskii L. N. Koren Yu. F. Kostyrya V. R. Starun V. A. Sazhin M. I. Kolesnik I. P. Davydov V. A. Butenko A. G. Belogrudov Yu. V. Bel'tyukov A. I. Korzhenevskii V. V. Rygalin L. Ya. Osipova V. P. Chernyavskaya 《Refractories and Industrial Ceramics》1967,8(7-8):406-410
Conclusions A method for producing roof products using magnesite-chromite clinker from caustic magnesite and Kimpersai chromite was developed and tested on an industrial scale. The dry method of producing the clinker from 20–25% chromite and 75–80% magnesite powder is the best.Roof refractories made with the use of magnesite-chromite clinker satisfy the requirements of GOST for all factors except spalling resistance.Translated from Ogneupory, No. 7, pp. 9–14, July, 1967. 相似文献
94.
The use of activity-based modeling to analyze the effect of land-use policies on travel behavior 总被引:1,自引:1,他引:0
Yoram Shiftan 《The Annals of Regional Science》2008,42(1):79-97
This paper suggests that in order to analyze the effect of land-use policies on travel behavior an integrated framework that
extend travel activity-based models to include various land-use issues such as residential location and work place should
be developed and use. The importance of analyzing various land-use policies on travel behavior is continuously increasing
as various policies such as transit-oriented developments, mixed land-use, different concentrations schemes, and more broadly
Smart Growth, are often suggested as a means to mitigate transportation problems. Given our limited understanding of the effects
of the various land-use polices on travel behavior it is imported to develop better approaches to analyze such policies. Activity-based
models, that treat travel as a derivation of the demand for personal activities, provides an opportunity to better understand
travel behavior as the explicit modeling of activities and the consequent tours and trips enable a more credible analysis
of responses to policies and their effect on traffic and air quality. The theoretical framework of activity-based models starts
with urban and land-use development as inputs; however, there is a need to translate this framework to analyze specific land-use
policies. This paper discusses the advantages and potential of activity-based models for analyzing the effect of land-use
policies on travel behavior. It suggests improvements that will extend the general framework to achieve a better understanding
of travelers’ responses to various land-use policies and shows its advantages over tip-based models, which simply do not have
such capabilities. The improved activity-based approach is illustrated through a case study based on the Portland activity-based
model combined with a stated-preference residential choice model. A package of land-use policies— including improved land-use,
school quality, safety, and transit service in the city center—is introduced, and its effect on household redistribution and
regional travel is tested using this integrated framework. The results of this case study show that the effects of the land-use
policies introduced had only marginal effects on regional travel. 相似文献
95.
A novel synthesis method of very high aspect ratio metal nanowires is described. The synthesis utilizes a nanoporous membrane as a template and self-electrophoresis as a directed force that continuously push formed nanowires out of the pores in a rate that is identical to the rate of their elongation. As a result, while the pores of membranes are only 6 microm long, the formed nanowires could be more than 100 microm long. 相似文献
96.
A patient being treated for sickle cell disease with hydroxyurea (1 g/d) conceived, and drug treatment was discontinued at nine weeks gestational age. The pregnancy and delivery were complicated by vaso-occlusive crises. A healthy male infant was born at 39 weeks with no evidence of congenital malformations. A literature review, including this case, suggests that the risk of hydroxyurea exposure during in pregnancy may have been overestimated. Further studies are required to determine its safety in pregnancy. 相似文献
97.
Topical treatment of normal skin with 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] or its synthetic analogs results in enhanced keratinocyte proliferation. Autocrine growth factors belonging to the epidermal growth factor (EGF) family play a major role in controlling keratinocyte proliferation. 1,25-(OH)2D3 enhanced the autonomous proliferation of HaCaT human keratinocytes in the absence of exogenous growth factors. Autonomous and 1,25-(OH)2D3-stimulated proliferations were inhibited by a specific inhibitor of EGF receptor (EGFR) tyrosine kinase, an EGFR-neutralizing antibody, heparin, the heparin antagonist hexadimethrine, and the proteoglycan sulfation inhibitor chlorate. These results indicate the involvement of proteoglycan-dependent EGFR ligands. The initial events in EGFR (i.e. ErbB1) mitogenic signal transduction are dimer formation with another ErbB protein and tyrosine cross-phosphorylation. By immunoprecipitation followed by Western blotting we showed that ErbB1/ErbB3 heterodimers are the major mitogenic signaling entity in 1,25-(OH)2D3-stimulated cells. 1,25-(OH)2D3 did not affect the levels of the proteoglycan-dependent EGFR ligands amphiregulin and heparin-binding EGF nor the synthesis of proteoglycans, as assessed by 35S labeling and ion exchange chromatography. 1,25-(OH)2D3 caused a marked increase in the cellular contents of ErbB1, ErbB2, and ErbB3 proteins. The increase in ErbB proteins that mediates signal transduction by EGFR ligands can account for the stimulatory effect of 1,25-(OH)2D3 on autonomous keratinocyte proliferation. 相似文献
98.
Hen Haddad Sharon Etzion Tatiana Rabinski Rivka Ofir Danielle Regev Yoram Etzion Jacob Gopas Aviv Goldbart 《International journal of molecular sciences》2021,22(21)
Obstructive sleep apnea syndrome (OSAS) patients suffer from cardiovascular morbidity, which is the leading cause of death in this disease. Based on our previous work with transformed cell lines and primary rat cardiomyocytes, we determined that upon incubation with sera from pediatric OSAS patients, the cell’s morphology changes, NF-κB pathway is activated, and their beating rate and viability decreases. These results suggest an important link between OSAS, systemic inflammatory signals and end-organ cardiovascular diseases. In this work, we confirmed and expanded these observations on a new in vitro system of beating human cardiomyocytes (CM) differentiated from human embryonic stem cells (hES). Our results show that incubation with pediatric OSAS sera, in contrast to sera from healthy children, induces over-expression of NF-κB p50 and p65 subunits, marked reduction in CMs beating rate, contraction amplitude and a strong reduction in intracellular calcium signal. The use of human CM cells derived from embryonic stem cells has not been previously reported in OSAS research. The results further support the hypothesis that NF-κB dependent inflammatory pathways play an important role in the evolution of cardiovascular morbidity in OSAS. This study uncovers a new model to investigate molecular and functional aspects of cardiovascular pathology in OSAS. 相似文献
99.
Polarisation insensitive semiconductor optical amplifier withintegrated electroabsorption modulators
Koren U. Miller B.I. Young M.G. Chien M. Raybon G. Brenner T. Ben-Michael R. Dreyer K. Capik R.J. 《Electronics letters》1996,32(2):111-112
The authors demonstrate a 1.55 μm wavelength multiquantum well semiconductor optical amplifier, integrated with bulk layer electroabsorption modulators and passive waveguide beam expanders at the input and output ports. The device has a fibre to fibre gain of 9 dB, an extinction ratio of 15 dB per modulator, a spectral range >35 nm, and polarisation sensitivity <1 dB 相似文献
100.
Wiesenfeld J.M. Gnauch A.H. Raybon G. Koren U. 《Photonics Technology Letters, IEEE》1992,4(7):708-711
A multiple-quantum-well optical amplifier is used at 8 Gb/s with high input power such that the average gain is compressed by 2.6 dB. Under these conditions, the output signal level is 35 mW and there is negligible intersymbol interference (ISI) penalty at the receiver. This is possible because of a rapid (7 ps) gain recovery process in the amplifier. A conventional semiconductor amplifier operating at a similar level of gain compression shows 2 dB ISI penalty 相似文献