检索结果-南通市图书馆

Dynamic Analysis for the Global Performance of An SPM-Feeder-Cage System Under Waves and Currents

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2015年第3期29卷 415-430页

作者： cristian CIFUENTES M.H.KIM Ocean Engineering Program Department of Civil Engineering Texas A&M University College Station

In the present study, the dynamic response of a coupled SPM-feeder-cage system under irregular waves and shear currents is analyzed. A numerical model is developed by using the commercial software Orca Flex. Hydrodynamics coefficients of the vessel are calculated by using a 3D diffraction/radiation panel program. First- and second-order wave forces are included in the calculations. Morison equation is used to compute the drag force on line elements representing the net. Drag coefficients are determined at every time step in the simulation considering the relative normal velocity between the structural elements and the fluid flow. The dynamic response of the coupled system is analyzed for various environments and net materials. The results of the study show the effects of solidity ratio of the net and vertical positions of the cage on the overall dynamic response of the system, confirming the viability of this type of configuration for future development of offshore aquaculture in deep waters.

关键词： offshore aquaculture SPM(single point mooring) feeder vessel connecting lines operational/survival environment drag force equivalent net cage grouping net modeling line tensions solidity ratio

A high Q terahertz metamaterial absorber using concentric elliptical ring resonators for harmful gas sensing applications

在线全文

学校读者我要写书评

暂无评论

Defence Technology（防务技术） 2023年第4期22卷 69-73页

作者： Bhargav Appasani Avireni Srinivasulu cristian Ravariu Department of Electronics Engineering Kalinga Institute of Industrial TechnologyBhubaneswarIndia Department of Electronics Engineering K R Mangalam UniversityGurgaonIndia Department of Electronic Devices Circuits and ArchitecturesPolytechnic University of BucharestBucharestRomania

A nearly perfect metamaterial absorber is proposed that can find utility in terahertz sensing *** design consists of two concentric elliptical ring resonators(ERRs)whose parameters are appropriately set to achieve dual band absorption with near perfect *** first absorption band at 3.62 THz having a Q-factor of 51.7 was caused due to the currents in the outer and inner *** second absorption peak at 3.814 THz having a Q factor of 1411.11 was a consequence of currents flowing across the gap between the two concentric ***,it is observed that the absorption bands are sensitive to the variation in refractive index of the surrounding *** sensitivity's in the absorption bands are 3 THz/RIU and 3.59 THz/RIU respectively.A sensor is proposed based on this design to detect harmful gases,which is demonstrated for detection of Methane and *** Q-factor and high sensitivity of the narrow band makes the design an excellent sensor for detecting variations in the refractive index.

关键词： Refractive index Plasma frequency Metamaterials Terahertz absorption Q-factor Gas sensing

Redox regulation of mammalian sperm capacitation

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2015年第4期17卷 583-590页

作者： cristian O'Flaherty Urology Research Laboratory Surgery Department (Urology Division) Faculty of Medicine McGill University Montreal Quebec Canada The Research Institute McGillUniversity Health Centre Montreal Quebec Canada.

Capacitation is a series of morphological and metabolic changes necessary for the spermatozoon to achieve fertilizing ability. One of the earlier happenings during mammalian sperm capacitation is the production of reactive oxygen species （ROS） that will trigger and regulate a series of events including protein phosphorylation, in a time-dependent fashion. The identity of the sperm oxidase responsible for the production of ROS involved in capacitation is still elusive, and several candidates are discussed in this review. Interestingly, ROS-induced ROS formation has been described during human sperm capacitation. Redox signaling during capacitation is associated with changes in thiol groups of proteins located on the plasma membrane and subcellular compartments of the spermatozoon. Both, oxidation of thiols forming disulfide bridges and the increase on thiol content are necessary to regulate different sperm proteins associated with capacitation. Reducing equivalents such as NADH and NADPH are necessary to support capacitation in many species including humans. Lactate dehydrogenase, glucose-6-phospohate dehydrogenase, and isocitrate dehydrogenase are responsible in supplying NAD （P） H for sperm capacitation. Peroxiredoxins （PRDXs） are newly described enzymes with antioxidant properties that can protect mammalian spermatozoa; however, they are also candidates for assuring the regulation of redox signaling required for sperm capacitation. The dysregulation of PRDXs and of enzymes needed for their reactivation such as thioredoxin/thioredoxin reductase system and glutathione-S-transferases impairs sperm motility, capacitation, and promotes DNA damage in spermatozoa leading to male infertility.

关键词： dehydrogenases oxidases peroxiredoxins reactive oxygen species spermatozoa thiols thioredoxins

Dispersed multiphase flows:advances in measuring,simulation and modeling

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2022年第8期38卷 1-3页

作者： cristian Marchioli Lihao Zhao Department of Engineering and Architecture University of UdineUdine33100Italy Key Laboratory of Applied Mechanics Department of Engineering MechanicsTsinghua UniversityBeijing100084China

Dispersed multiphase flows are commonly encountered in a wide variety of natural and industrial applications,from sedimentation in rivers and plankton surfacing in oceanic flows to fluidized bed in chemical reactors and pneumatic conveying *** these flows,a dispersed phase(con-sisting of particles,droplets and/or bubbles)is transported by a carrier *** interaction between the phases re-sults in complex dynamics(e.g.,transport,spatial clustering,and deformation or break-up)that is rich in physics and poses a wide spectrum of theoretical,computational,and experimental *** challenges are at the very core of the research efforts made by the multiphase flow community over the past decades.

关键词： multiphase flows dispersed

In vivo oxidative stress alters thiol redox status of peroxiredoxin 1 and 6 and impairs rat sperm quality

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2017年第1期19卷 73-79页

作者： Yannan Liu cristian O'Flaherty The Research Institute of the McGill University Health Centre Montreal QC H4A 3J1 Canada Department of Surgery (Urology Division) McGill University Montreal QC H4A 3J1 Canada Department of Obstetrics and Gynecology McGill University Montreal QC H4A 3J1 Canada Department of Pharmacology and Therapeutics McGill University Montreal QC H3G 1Y6 Canada

Oxidative stress, the imbalance between the production of reactive oxygen species （ROS） and antioxidant activity is a major culprit of male infertility. Peroxiredoxins （PRDXs） are major antioxidant enzymes of mammalian spermatozoa and are thiol oxidized and inactivated by ROS in a dose-dependent manner. Their deficiency and/or inactivation have been associated with men infertility. The aim of this study was to elucidate the impact of oxidative stress, generated by the in vivo tert-butyl hydroperoxide （tert-BHP） treatment on rat epididymal spermatozoa during their maturation process. Adult Sprague-Dawley males were treated with 300 -moles tert-BHP/kg or saline （control） per day intraperitoneal for 15 days. Lipid peroxidation （2-thibarbituric acid reactive substances assay）, total amount and thiol oxidation of PRDXs along with the total amount of superoxide dismutase （SOD）, motility and DNA oxidation （8-hydroxy-deoxyguanosine） were determined in epididymal spermatozoa. Total amount of PRDXs and catalase and thiol oxidation of PRDXs were determined in caput and cauda epididymis. While animals were not affected by treatment, their epididymal spermatozoa have decreased motility, increased levels of DNA oxidation and lipid peroxidation along with increased PRDXs （and not SOD） amounts. Moreover, sperm PRDXs were highly thiol oxidized. There was a differential regulation in the expression of PRDX1 and PRDX6 in the epididymis that suggests a segment-specific role for PRDXs. In conclusion, PRDXs are increased in epididymal spermatozoa in an attempt to fight against the oxidative stress generated by tert-BHP in the epididymis. These findings highlight the role of PRDXs in the protection of sperm function and DNA integrity during epididymal maturation.

关键词： antioxidant enzymes DNA oxidation epididymis reactive oxygen species spermatozoa thiol oxidation

Global Trends of Usage of Chlorophyll Fluorescence and Projections for the Next Decade

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plant Phenomics 2020年第1期2卷 409-418页

作者： Alonso Zavafer Leen Labeeuw cristian Mancilla Research School of Biology The Australian National UniversityCanberraACTAustralia University of Technology Sydney Climate Change ClusterFaculty of ScienceSydneyNSW 2007Australia Independent Researcher La FloridaChile

Chlorophyll fluorescence is the most widely used set of techniques to probe photosynthesis and plant *** great versatility has given rise to different routine methods to study plants and *** three main technical platforms are pulse amplitude modulation(PAM),fast rise of chlorophyll fluorescence,and fast repetition ***-induced fluorescence(SIF)has also gained interest in the last few *** have compared their advantages and their underlying theory,with many arguments advanced as to which method is the most accurate and *** date,no data has assessed the exact magnitude of popularity and influence for each *** this work,we have taken the bibliometrics of the past decade for each of the four platforms,have evaluated the public scientific opinion toward each method,and possibly identified a geographical *** used various metrics to assess influence and popularity for the four routine platforms compared in this study and found that,overall,PAM currently has the highest values,although the more recent SIF has increased in popularity rapidly during the last *** indicates that PAM is currently one of the fundamental tools in chlorophyll fluorescence.

关键词： algae routine Fluorescence

Tales of the Tail and Sperm Head Aches --Changing concepts on the prognostic significance of sperm pathologies affecting the head, neck and tail

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2012年第1期14卷 14-23,174页

作者： Hector E Chemes cristian Alvarez Sedo Laboratory of Testicular Physiology and Pathology Center for Research in Endocrinology National Research Council （CONICET） Endocrinology Division Buenos Aires Children＇s Hospital Gallo 1330 C1425SEFD Buenos Aires Argentina Centro de Estudios en Ginecologia y Reproduccion （CEGyR） C1425SEFD Buenos Aires Argentina

This article presents an update on the variable prognostic significance of different sperm pathologies in patients with severe male factor infertility due to morphology and motility disorders. Severe asthenozoospermia is one of the leading causes of male infertility as spermatozoa cannot reach the oocyte and/or penetrate normally. Identifying structural causes of sperm immotility was of great concern before the advent of intracytoplasmic sperm injection （ICSI）, because immotility was the limiting factor in the treatment of these patients. In these cases, in vitro methods are used to identify live spermatozoa or stimulate sperm motility to avoid selection of non-viable cells. With these advances, fertilization and pregnancy results have improved dramatically. The identification of genetic phenotypes in asthenozoospermia is important to adequately inform patients of treatment outcomes and risks. The one sperm characteristic that seriously affects fertility prognosis is teratozoospermia, primarily sperm head and neck anomalies. Defects of chromatin condensation and acrosomal hypoplasia are the two most common abnormalities in severe teratozoospermia. The introduction of microscopic methods to select spermatozoa and the development of new ones to evaluate sperm quality before ICSI will assure that ultrastructural identification ofsperm pathologies will not only be of academic interest, but will also be an essential tool to inform treatment choice. Herein, we review the differential roles played by sperm components in normal fertilization and early embryo development and explore how assisted reproductive technologies have modified our concepts on the prognostic significance of sperm pathologies affecting the head, neck, mid-piece and tail.

关键词： acrosomal hypoplasia chromatin anomalies fertility prognosis intracytoplasmic sperm injection intracytoplasmic injection of morphologically selected spermatozoa sperm neck defects sperm pathologies tail abnormalities teratozoospermia

Sperm quality in mice acutely treated with parathion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2000年第2期2卷 147-150页

作者： cristian Sobarzo Eduardo Bustos-Obregon Faculty of Basic Sciences Catholic University of Temuco and Biology of Reproduction Unit Program of Morphology ICBM Faculty of Medicine University of Chile. Santiage 7 Chile.Faculty of Basic Sciences Catholic University of Temuco and Biology of Reproduction Unit Program of Morphology ICBM Faculty of Medicine University of Chile. Santiage 7 Chile.

Aim: To investigate the toxic effect of a single injection of the organophosphorous agropesticide, parathion, on sper-matogenesis in immature male mice. Methods: Seven-day old mice received a single injection of parathion intraperi-toneally at a dose of 1/3 LD_50. The epididymal sperm count, sperm morphology and chromatin thermal stability wereanalyzed 28 and 50 days after injection. Results: Sperm counts were decreased and teratozoospermia and thermal de-naturation of DNA increased after parathion injection. Sperm parameters were changed to a greater extent in younger an-imals, denoting a higher lability of spermatogenic process at its beginning. The damages could recover a long time afterparathion administration. Conclusion: Organophosphorous agropesticides are testicular toxicants, eliciting reversiblecytotoxic and cytogenetic alterations in germ cells.

关键词： epididymis spermatozoa organophosphorous compounds agropesticides spermatogenesis

Bi-normalized response spectra and seismic intensity in Bucharest for 1986 and 1990 Vrancea seismic events

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2014年第1期13卷 125-135页

作者： Florin Pavel Radu Vacareanu cristian Neagu Andrei Pricopie Department of Reinforced Concrete Structures Technical University of Civil Engineering BucharestRomania Department of Strength of Materials Bridges and TunnelsTechnical University of Civil Engineering BucharestRomania

The Vrancea subcrustal earthquakes of August 30,1986 and May 30,1990 are the two most recent seismic events that have occurred in Romania with moment magnitudes M W ≥ *** spectral analysis of the strong ground motions recorded in Bucharest reveals that despite small differences in magnitude between the 1986 and 1990 earthquakes,their frequency contents are very different,sometimes even *** main focus of this study is to conduct a comparative analysis of the response spectra in terms of the bi-normalized response spectra(BNRS) proposed by Xu and Xie(2004 and 2007) for strong ground motions recorded in Bucharest during these two seismic *** mean absolute acceleration and relative velocity response spectra for the two earthquakes are discussed and ***,the mean bi-normalized absolute acceleration and normalized relative velocity response spectra with respect to the control period T C are computed for the ground motions recorded in Bucharest in 1986 and *** predominant period T P is also used in this study for the normalization of the spectral period ***,the methodology proposed by Martinez-Perreira and Bommer(1998) is applied in order to estimate the seismic intensity of the two *** results are discussed and several conclusions regarding the possibility of using the bi-normalized response spectra(BNRS) are given.

关键词： response spectra bi-normalized response spectra dynamic amplifi cation factor control period damage potential parameters