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The clinical impact of bacterial biofilms

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International Journal of Oral Science 2011年第2期3卷 55-65页

作者： niels hoiby Oana Ciofu Helle Krogh Johansen Zhi-jun Song Claus Moser Peter Ostrup Jenser Soren Molin Michael Givskov Tim Tolker-Nieisen Thomas Bjamsholt Department of Clinical Microbiology Rigshospitalet Institute for International Health Medical Microbiology and Immunology BloScience and Technology Biocentrum Danish Technical University

Bacteria survive in nature by forming biofilms on surfaces and probably most, if not all, bacteria （and fungi） are capable of forming biofilms. A biofilm is a structured consortium of bacteria embedded in a self-produced polymer matrix consisting of polysaccharide, protein and extracellular DNA. Bacterial biofilms are resistant to antibiotics, disinfectant chemicals and to phagocytosis and other components of the innate and adaptive inflammatory defense system of the body. It is known, for example, that persistence of staphylococcal infections related to foreign bodies is due to biofilm formation. Likewise, chronic Pseudomonas aeruginosa lung infections in cystic fibrosis patients are caused by biofilm growing mucoid strains. Gradients of nutrients and oxygen exist from the top to the bottom of biofilms and the bacterial cells located in nutrient poor areas have decreased metabolic activity and increased doubling times. These more or less dormant cells are therefore responsible for some of the tolerance to antibiotics. Biofilm growth is associated with an increased level of mutations. Bacteria in biofilms communicate by means of molecules, which activates certain genes responsible for production of virulence factors and, to some extent, biofilm structure. This phenomenon is called quorum sensing and depends upon the concentration of the quorum sensing molecules in a certain niche, which depends on the number of the bacteria. Biofilms can be prevented by antibiotic prophylaxis or early aggressive antibiotic therapy and they can be treated by chronic suppressive antibiotic therapy. Promising strategies may include the use of compounds which can dissolve the biofilm matrix and quorum sensing inhibitors, which increases biofilm susceptibility to antibiotics and phagocytosis.

关键词： bacterial biofilm biofilm infection antibiotic resistance quorum sensing

卡介苗预先免疫对大鼠慢性绿脓杆菌性肺炎的影响

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现代免疫学 2004年第2期24卷 138-141页

作者：郭向华宋志军吴红闫萍覃雪君 Kalai Mathee niels hoiby 唐步坚仇晓强陈一强广西医科大学医学科学实验中心南宁530021 Department of Biological Sciences Florida International University Department of Clinical Microbiology University Hospital of Copenhagen

为了探讨卡介苗 (BCG )预先免疫对大鼠慢性绿脓杆菌 (PA )性肺炎模型的影响。采用BCG或灭菌生理盐水皮内注射预先免疫 3周 ,然后由支气管内予以PA攻击 ;2周后评估各组的肺部细菌学、肺组织病理学、肺部细胞因子 (IL 4、IFN γ、TNF α ... 详细信息

为了探讨卡介苗 (BCG )预先免疫对大鼠慢性绿脓杆菌 (PA )性肺炎模型的影响。采用BCG或灭菌生理盐水皮内注射预先免疫 3周 ,然后由支气管内予以PA攻击 ;2周后评估各组的肺部细菌学、肺组织病理学、肺部细胞因子 (IL 4、IFN γ、TNF α )反应、血清PA特异性抗体IgG水平的变化。结果显示BCG免疫组肺组织内的IFN γ、TNF α水平显著升高 (P 0 0 5 )。以上结果提示BCG接种能够诱导肺部Th1型免疫反应 ,加快PA性肺炎大鼠肺部的细菌清除。

关键词：卡介苗绿脓杆菌肺部感染囊性纤维化动物模型细胞因子医院感染免疫疗法

Normal reference ranges for semen quality and their relations to fecundity

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Asian Journal of Andrology 2010年第1期12卷 95-98页

作者： niels E. Skakkebaek University Department of Growth and Reproduction Rigshospitalet Copenhagen DK-2100 Denmark

Several recent studies have shown that the fecundity of a man decreases progressively with sperm concentrations below 40 million spermatozoa per mL. Therefore, it is unfortunate that the new World Health Organization guidelines for semen analysis recommend lowering the lower cutoff value for normal sperm concentration from 20 to 15 million spermatozoa per mL. As a result large groups of subfertile men across the world may not receive appropriate andrological help in the future.

关键词： semen quality infertility sperm morphology fecundity

Oncostatin M:a love-hate relationship in neuroinflammation

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Neural Regeneration Research 2024年第12期19卷 2571-2572页

作者： Doryssa Hermans niels Hellings Bieke Broux University MS Center Campus DiepenbeekDiepenbeekBelgium Neuro-Immune Connections and Repair Lab Department of Immunology and InfectionBiomedical Research InstituteHasselt UniversityDiepenbeekBelgium

Oncostatin M and multiple sclerosis:Every 5minutes,someone in the world is diagnosed with multiple sclerosis(MS),a chronic inflammatory and degenerative disease of the central nervous system(CNS).MS appears in unpredictable episodes of symptoms,which are highly patient-dependent,but often include visual impairment,muscle weakness/spasms,fatigue,cognitive difficulties,and *** sexual dysfunction.

关键词： visual bladder someone

Towards an L^p Potential Theory for Sub-Markovian Semigroups:Kernels and Capacities

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Acta Mathematica Sinica,English Series 2006年第4期22卷 1227-1250页

作者： niels JACOB RenéL.SCHILLING Department of Mathematics University of Wales SwanseaSingleton ParkSwansea SA 2 8 PP.United Kinadom FB 12-Mathematik Philipps-Universitat MarburgD-35032 MarburgGermany

We study in fairly general measure spaces （X,μ） the （non-linear） potential theory of L^p sub-Markovian semigroups which are given by kernels having a density with respect to the underlying measure. In terms of mapping properties of the operators we provide sufficient conditions for the existence （and regularity） of such densities. We give various （dual） representations for several associated capacities and, in the corresponding abstract Bessel potential spaces, we study the role of the truncation property. Examples are discussed in the case of R^n where abstract Bessel potential spaces can be identified with concrete function spaces.

关键词： nonlinear potential theory (r,p)-capacity Bessel potential space gamma.transform sub-Markovian semigroup

Influence of liquid layers on energy absorption during particle impact

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Particuology 2009年第4期7卷 245-259页

作者： Sergiy Antonyuk Stefan Heinrich niels Deen Hans Kuipers Hamburg University of Technology Institute of Solids Process Engineering and Particle Technology Denickestr. 15 21071 Hamburg Germany University of Twente Fundamentals of Chemical Reaction Engineering Faculty of Science and Technology PO Box 217 Enschede 7500 AE The Netherlands

The influence of the thickness of a covering liquid layer and its viscosity as well as the impact velocity on energy loss during the normal impact on a flat steel wall of spherical granules with a liquid layer was studied. Free-fall experiments were performed to obtain the restitution coefficient of elastic-plastic γ- Al2O3 granules by impact on the liquid layer, using aqueous solutions of hydroxypropyl methylcellulose with different concentrations for variation of viscosity （1-300 mPa s）, In the presence of a liquid layer, increase of liquid viscosity decreases the restitution coefficient and the minimum thickness of the liquid layer at which the granule sticks to the wall. The measured restitution coefficients were compared with experiments performed without liquid layer. In contrast to the dry restitution coefficient, due to viscous losses at lower impact velocity, higher energy dissipation was obtained, A rational explanation for the effects obtained was given by results of numerically solved force and energy balances for a granule impact on a liquid layer on the wall. The model takes into account forces acting on the granule including viscous, surface tension, capillary, contact, drag, buoyancy and gravitational forces. Good agreement between simulations and experiments has been achieved.

关键词： Granule impact Restitution coefficient Energy dissipation Liquid layer Liquid bridge

A Review of Self-healing Metals: Fundamentals, Design Principles and Performance

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Acta Metallurgica Sinica(English Letters) 2020年第9期33卷 1167-1179页

作者： Shasha Zhang niels van Dijk Sybrand van der Zwaag College of Materials and Technology Nanjing University of Aeronautics and AstronauticsNanjing 211106China Key Laboratory of Materials Preparation and Protection for Harsh Environment(Nanjing University of Aeronautics and Astronautics) Ministry of Industry and Information TechnologyNanjing 211106China Fundamental Aspects of Materials and Energy Group Faculty of Applied SciencesDelft University of TechnologyMekelweg 152629 JB DelftThe Netherlands Novel Aerospace Materials Group Faculty of Aerospace EngineeringDelft University of TechnologyKluyverweg 12629 HS DelftThe Netherlands School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

Self-healing metals possess the capability to autonomously repair structural damage during service. While self-healing concepts remain challenging to be realized in metals and metallic systems due to the small atomic volume of the mobile atoms, the slow diffusion unless at high temperatures and the strong isotropic metallic bonds, the scientific interest has increased sharply and promising progress is obtained. This article provides a comprehensive and updated review on the developments and limitations associated with the various modes of potentially healable damage induced in metals and alloys, i.e., stressinduced damage, irradiation-induced damage in bulk materials and contact damage in corrosion protective coatings. The spontaneous intrinsic healing mechanisms not requiring external assistance other than the material operating at the right temperature and an assisted healing mechanism with external intervention are reviewed. Promising strategies to achieve self-healing in metals are identified. Finally, we give some prospects for future research directions in self-healing metals.

关键词： Metal Self-healing Creep behavior Fatigue damage Irradiation Coating

Semi-analytical calculation model for friction of polymers on the example of POM|PE-UHMW and steel|PE-UHMW

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Friction 2024年第10期12卷 2355-2369页

作者： André BERGMANN Jens SUMPF niels DALLINGER Martin MONEKE Markus GOLDER Professorship of Conveying Engineering and Materials Handling Chemnitz University of TechnologySachsen 09126Germany Institute of Plastics Engineering Darmstadt University of Applied SciencesDarmstadt 64295Germany

In this paper,a semi-analytical calculation model for the coefficient of friction(COF)of single spherical protrusions is *** allows the prediction of the deformative friction part(μ_(def))and adhesive friction part(μ_(def))of the friction pairings steel|polyethylene with ultra-high molecular weight(PE-UHMW)and polyoxymethylene(POM)|*** experimental studies included unlubricated friction tests,which served to determine the total COF(μ_(def)),as well as tests being lubricated with silicone oil,from whichμ_(def)is *** on the verification tests,it could be shown that both states of lubrication result in the same deformation and that the relationship between the rear angle(w)andμ_(def)postulated in the calculation model is ***,friction tests with segmented spheres were carried out,which allow a specific variation of *** can be concluded that for both pairings theμ_(def)is generally of minor significance(approx.1/3μ_(tot))and the influence of theμ_(adh)predominates(approx.2/3μ_(tot))the friction *** themtot decreases with increasing contact pressure especially in the low pressure range and depends on the form of motion(continuous and discontinuous).

关键词： tribology friction polymers model contact polyoxymethylene(POM) polyethylene with ultra-high molecular weight(PE-UHMW)

Assimilation of Feng-Yun-3B Satellite Microwave Humidity Sounder Data over Land

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Advances in Atmospheric Sciences 2018年第3期35卷 268-275页

作者： Keyi CHEN niels BORMANN Stephen ENGLISH Jiang ZHU School of Atmospheric Sciences Chengdu University of Information & Technology Chengdu Sichuan 610225 China International Centre for Climate and Environment Sciences Institute of Atmospheric Physics China Beijing 100029 China European Centre for Medium-Range Weather Forecasts Reading RG2 9AX UK

The ECMWF has been assimilating Feng-Yun-3B （FY-3B） satellite microwave humidity sounder （MWHS） data over ocean in an operational forecasting system since 24 September 2014, It is more difficult, however, to assimilate microwave observations over land and sea ice than over the open ocean due to higher uncertainties in land surface temperature, surface emissivity and less effective cloud screening. We compare approaches in which the emissivity is retrieved dynamically from MWHS channel l [150 GHz （vertical polarization）] with the use of an evolving emissivity atlas from 89 GHz observations from the MWHS onboard NOAA and EUMETSAT satellites. The assimilation of the additional data over land improves the fit of short-range forecasts to other observations, notably ATMS （Advanced Technology Microwave Sounder） humidity channels, and the forecast impacts are mainly neutral to slightly positive over the first five days. The forecast impacts are better in boreal summer and the Southern Hemisphere. These results suggest that the techniques tested allow for effective assimilation of MWHS/FY-3B data over land.

关键词： data assimilation over land Chinese satellite FY-3B Microwave Humidity Sounder