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Study on the wind field and pollutant dispersion in street canyons using a stable numerical method

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Journal of Environmental Sciences 2005年第3期17卷 488-490页

作者： dennis Y.C. LEuNG Department of Mechanical Engineering the University of Hong Kong Hong Kong China

A stable finite element method for the time dependent Navier-Stokes equations was used for studying the wind flow and pollutant dispersion within street canyons. A three-step fractional method was used to solve the velocity field and the pressure field separately from the governing equations. The Streamline upwind Petrov-Galerkin(SuPG) method was used to get stable numerical results. Numerical oscillation was minimized and satisfactory results can be obtained for flows at high Reynolds numbers. Simulating the flow over a square cylinder within a wide range of Reynolds numbers validates the wind field model. The Strouhal numbers obtained from the numerical simulation had a good agreement with those obtained from experiment. The wind field model developed in the present study is applied to simulate more complex flow phenomena in street canyons with two different building configurations. The results indicated that the flow at rooftop of buildings might not be assumed parallel to the ground as some numerical modelers did. A counter-clockwise rotating vortex may be found in street canyons with an inflow from the left to right. In addition, increasing building height can increase velocity fluctuations in the street canyon under certain circumstances, which facilitate pollutant dispersion. At high Reynolds numbers, the flow regimes in street canyons do not change with inflow velocity.

关键词： finite element method Streamline upwind Petrov-Galerkin method three-step fractional method

Radiological findings of February 2023 twin earthquakes-related spine injuries

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World Journal of Radiology 2024年第9期16卷 398-406页

作者： Ayşenur Bolukçu Ahmet Gürkan Erdemir İlkay Sedakatİdilman Adalet Elçin Yildiz GökçenÇobanÇifçi Mehmet Ruhi Onur Erhan Akpinar Department of Radiology Hacettepe UniversityFaculty of MedicineAnkara 06100Türkiye Department of Radiology University of ChicagoChicagoIL 60637United States

BACKGROuND The February 6,2023,twin earthquakes in Türkiye caused significant structural damage and a high number of injuries,particularly affecting the spine,which underscores the importance of understanding the distribution and nature of vertebral injuries in disaster *** To investigate the distribution of radiological findings of vertebral injuries in patients referred to a major tertiary center during the February 6,2023 twin earthquakes in Tü*** With the approval of the institutional ethics committee,1216 examinations of 238 patients transferred from the region to a tertiary major hospital after the twin earthquakes of February 6,2023,were retrospectively analyzed for spine *** Spine computed tomography(CT)scans were performed in 192 of 238 patients with a suspected spinal injury,42 of whom also had an magnetic resonance imaging(MRI).In 86 of 192 patients(44.79%;M:F=33:53)a spinal fracture was detected on CT and in 33 of 42 patients(78.57%;M:F=20:13)a spinal injury was found on *** the 86 patients in whom vertebral injury was detected,fractures were detected in the Denis-B group in 33,Denis-C in 4,Denis-D in 20 and Denis-E in 11 *** the vertebral bodies:40"compression fractures",17"burst fractures",5"translational dislocation fractures",5"flexion-distraction fractures"and 58"prolonged forced fetal posture fractures"were *** addition,isolated transverse or spinous process fractures were found in eighteen *** Our study highlights the prevalence and diverse spectrum of spinal injuries following the February 6,2023 twin earthquakes in Turkey underscoring the urgent need for effective management strategies in similar disaster scenarios,and emphasizing the"prolonged forced fetal posture"damage we encountered in earthquake victims who remained under the collapse for a long time.

关键词： Accidental injuries Compression fractures Crush injuries Earthquakes Spine

Metabolic integration during the evolutionary origin of mitochondria

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Cell Research 2003年第4期13卷 229-238页

作者： dennis G SEARCY Biology Department university of Massachusetts Amherst MA 01003-9297 uSA

Although mitochondria provide eukaryotic cells with certain metabolic advantages, in other ways they may be disadvantageous. For example, mitochondria produce reactive oxygen species that damage both nucleocytoplasm and mitochondria, resulting in mutations, diseases, and aging. The relationship of mitochondria to the cytoplasm is best understood in the context of evolutionary history. Although it is clear that mitochondria evolved from symbiotic bacteria, the exact nature of the initial symbiosis is a matter of continuing debate. The exchange of nutrients between host and symbiont may have differed from that between the cytoplasm and mitochondria in modern cells. Speculations about the initial relationships include the following. (1) The pre-mitochondrion may have been an invasive, parasitic bacterium. The host did not benefit. (2) The relationship was a nutritional syntrophy based upon transfer of organic acids from host to symbiont. (3) The relationship was a syntrophy based upon H2 transfer from symb

关键词： mitochondria (origin) symbiosis sulfur rickettsia hydrogenosome.

Dolichocolon revisited: An inborn anatomic variant with redundancies causing constipation and volvulus

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World Journal of Gastrointestinal Surgery 2018年第2期10卷 6-12页

作者： dennis Raahave Department of Surgery Copenhagen University North Sealand Hospital

The objective of this review is to examine whether a redundant colon gives rise to symptoms like constipation and volvulus. In 1820, Monterossi made drawings of colons with displacements and elongation of the colon found during autopsy. In 1912, Kienb?eck first visualized a redundant colon using bismuth, and Lardennois and Auborg named the anatomic variant dolichocolon in 1914. The criteria were later: A sigmoid loop rising over the line between the iliac crests, a transverse colon below the same line and extra loops at the flexures. The incidence of dolichocolon is 1.9%-28.5%. Dolichocolon seems to be congenital, as fetuses, newborns, and infants exhibit colonic redundancies. Studies have identified a triade of constipation, abdominal pain, and distension. Colon transit time was recently shown to increase significantly with increased number of redundancies, which increases abdominal pain, bloating and infrequent defecation. The diagnosis of dolichocolon is established by barium enema or CT-colonography. Treatment is conservative, or surgical in case of volvulus or refractory constipation.

关键词： Dolichocolon Colon elongatum Functional gastrointestinal disorders Constipation Volvulus

Guardians of the eye:new tales about retinal microglia and other ocular macrophages

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Neural Regeneration Research 2022年第6期17卷 1275-1277页

作者： dennis-Dominik Rosmus Peter Wieghofer Institute of Anatomy Leipzig UniversityLeipzigGermany

Macrophages are highly versatile and plastic immune cells that are localized in nearly all organs of the body and contribute to a plethora of physiological and pathological processes in *** their roles as major players in the“first line of defense”under inflammatory conditions,macrophages are known to participate in tissue homeostasis maintenance.

关键词： organs homeostasis ocular

ultraviolet discharges from a radio-frequency system for potential biological/chemical applications

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Chinese Physics B 2017年第8期26卷 157-161页

作者： Joseph Ametepe Sheng Peng dennis Manos Georgia Gwinnett College School of Science and TechnologyLawrenceville-GA 30078USA EXFO Mississaugaon Canada L5N 6H7 College of William and Mary Department of PhysicsWilliamsburgVA 2385USA

In this work, we describe a new electrode-less radio-frequency（RF） excitation technique for generating excimers in the vacuum ultraviolet（VuV） and ultraviolet（uV） spectral regions for potential biological/chemical applications. Spectra data of Xe~＊_2, XeI~＊, and KrI~＊ generated by this new technique are presented. Optical efficiency of the lamp system ranges from 3% to 6% for KrI~＊, 7% to 13% for XeI~＊, and 15% to 20% for Xe~＊_2. Also, results of irradiating E-coli with XeI~＊discharge from this lamp system is presented to show one of the promising applications of such electrode-less *** new RF lamp system offers an interesting addition to the already existing technologies for generating VuV and uV light for various biological, physical, and chemical processes especially those requiring large area for high productivity.

关键词： radio-frequency ultraviolet light Xe2* XeI* KrI* excimers escherichia coli

The Study of Deposition Parameters, Properties for PVD Ti_xN and Cr_xN Coatings using a Closed Field unbalanced Magnetron Sputter Ion Plating System

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材料热处理学报 2004年第5B期25卷 841-846页

作者： HailinSun SusanField JianChen dennis.G.Teer TeerCoatingsLtd. WestStoneHouseBerryHillIndustrialEstateDroitwichWR99ASUK StateKeyLaboratoryofMechanicalBehaviourforMaterialss Xi＇anJiaotongUniversityP.R.CHINA

Closed Field unbalanced Magnetron Sputter Ion Plating (CFuBMSIP) systems have been used increasingly for PVD coating in recent years. TiN and CrN coatings, commonly used as the basic coating for a number of different hard coatings, have been chosen to study the coating process parameters for the CFuBMSIP system. In this paper, the process parameters, such as substrate temperature, substrate bias and OEM control, have been carefully examined to achieve hard and wear-resistance coatings with good adhesion. The coating structure and orientation were found to change according to the coating parameters. The Rockwell test and Scratch test were carried out to examine the coating adhesion; pin-on-disc testing was used to estimate the wear-resistant; micro-hardness was also used to determine coating hardness. HSS drill testing has been carried out to study the general properties of the coating for cutting tool application. A combination of process parameters can be selected to achieve good performance for the TiN and CrN coatings.

关键词： PVD 衬底温度磁控管溅射 TixN涂层 CrxN涂层 OEM

Determination of Hydroxylated Polybrominated Diphenyl Ethers in Blood from Baltic Grey Seals

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Journal of Analysis and Testing 2019年第4期3卷 287-294页

作者： dennis Lindqvist Lillemor Asplund Department of Environmental Science and Analytical Chemistry Stockholm University10691 StockholmSweden

Naturally produced hydroxylated polybrominated diphenyl ethers(OH-PBDEs)have been extensively studied in the lower end of the Baltic Sea food *** OH-PBDE congeners have displayed increasing concentrations over the last 30 years in herring(Clupea harengus)from the Baltic ***,studies on the top carnivores in the Baltic Sea are *** data on OH-PBDEs exist for ringed seal(Pusa hispida)from the Gulf of Bothnia,but only a limited amount of data have been produced with regard to Baltic grey seal(Halichoerus grypus),and seals from the Baltic proper.A method was developed and evaluated for quantification of OH-PBDEs in coagulated whole *** method was applied on blood obtained from dead grey seals originating from different parts of the Baltic *** levels of OH-PBDEs were observed to be low in the analyzed seals in comparison with reported levels in white-tailed sea eagle nestlings(Halizeetus albicilla),and some Baltic fish *** levels of the dominant congener,6-OH-BDE47,were statistically significantly higher in seals from the Baltic proper than in seals from the Gulf of *** polychlorinated biphenyls(OH-PCBs)were observed to be of much higher concentration than the OH-PBDEs in the analyzed *** average concentration of the dominant OH-PCB congener,4-OH-CB107,was one order of magnitude greater than that of 6-OH-BDE47.

关键词： Phenols OH-PBDEs Seal Blood Analysis Analytical methods

Release the iron: does the infection of magnetotactic bacteria by phages play a role in making iron available in aquatic environments?

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Journal of Oceanology and Limnology 2021年第6期39卷 2063-2069页

作者： Igor TAVEIRA dennis ABAZYLINSKI Fernanda ABREu Instituto de Microbiologia Paulo de Góes Departamento de Microbiologia GeralUniversidade Federal do Rio de JaneiroRio de Janeiro 21941-902Brazil School of Life Sciences University of Nevada at Las VegasLas Vegas 94720USA

Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the *** structures are ferrimagnetic organelles that impart a magnetic moment to the *** succeed in producing magnetosomes,MTB accumulate iron in(i)cytoplasm;(ⅱ)magnetosomes;and(ⅲ)nearby the *** has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia *** are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and *** current work addresses the putative role of phages that infect MTB on the iron biogeochemical *** phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments?Are phages critical players in driving magnetosome biomineralization genes(BGs)horizontal transfer?Further investigation of those events,including frequency of occurrence,is necessary to fully comprehend MTB’s effect on iron cycling in aqueous environments.

关键词： horizontal gene transfer iron biogeochemical cycle magnetotactic bacteria magnetosome biomineralization genes phages