Analyse komplexer biologischer Proben mittels oberflächenverstärkter Ramanspektroskopie (SERS)

Diese Studie beschäftigt sich mit dem Nachweis biologischer Proben mit Hilfe der Raman-Mikroskopie. Um ausreichende Signalintensitäten auch bei niedrigen Konzentrationen zu erhalten, wurde insbesondere der Effekt der oberflächenverstärkten Raman-Streuung (SERS) näher untersucht. Als Proben dienten DNA aus Hering-Sperma und das Protein Albumin. Zur Verstärkung des Raman-Spektrums wurden zwei unterschiedliche Methoden verwendet. Zum Einen wurden in einem chemischen Reduktionsprozess Nanosilberpartikel hergestellt und den biologischen Proben zugemischt. Zum Anderen wurden mit Hilfe laserangeregter periodischer Oberflächenstrukturierung (LIPSS) erzeugte nanostrukturierte Silberoberflächen als Substrate für die Proben verwendet. Diese Methode wurde bislang nicht für die SERS-Analyse biologischer Proben eingesetzt. Erste hier präsentierte Messungen zeigen, dass beide Verfahren signifikante SERS-Verstärkungen liefern und potentiell leistungsstarke Methoden für die zerstörungsfreie Analyse biologischer Proben darstellen

HPLC-DAD analysis, antimicrobial and antioxidant properties of aromatic Herb Melissa officinalis L., aerial parts extracts

Treating specific tissues without affecting other regions is a difficult task. It is desirable to target the particular tissue where the chemical has its biological effect. To study this phenomenon computationally, in this work we numerically study a mathematical model which is written as a nonlinear system composed by three parabolic partial differential equations. The variables involved in the model are the concentration of the chemical, the concentration of the binding protein and the concentration of the chemical bound to the protein. Our aim is to propose a fully discrete approximation of this problem, using the Finite Element Method and a semi-implicit Euler scheme, in order to solve it numerically. This discrete problem is analysed, obtaining a discrete stability property and some a priori error estimates that show the algorithm converges linearly if the continuous solution is regular enough. Also, some representative examples are shown, as well as the numerical verification of the convergence.Universidade de Vig

Prévention des infections du site opératoire les stratégies thérapeutique et préventives.

Les infections du site opératoire constituent La complication la plus redoutable des interventions chirurgicales, et l’une des infections nosocomiales les plus fréquentes. Leurs conséquences peuvent être dramatiques pour le patient (complications, séjour prolongé, mortalité) et coûteuses pour les structures de santé. Ceci exige une prise de conscience et un engagement collectif de tout le personnel hospitalier pour espérer des résultats satisfaisants d’une prévention efficace. Notre travail permet une approche des différents moyens de prévention des infections postopératoires en milieu chirurgical. Dans cette optique, une stratégie efficace de prévention est basée sur des éléments essentiels: • La meilleure connaissance des facteurs de risque de l’infection et la détermination correcte des différents modes de contamination. • Le raccourcissement du séjour hospitalier du malade. • La détermination d’antibioprophylaxie. préopératoire d’un protocole adapté • La préparation idéale du patient et de l’équipe médicale à l’intervention chirurgicale. • Le respect des critères d’asepsie du bloc opératoire et de stérilité du matériel médico-chirurgical. • La prise en charge correcte du malade dans la période postopératoire

Thermal conditions for laser chemical micro processing of metals

This work deals with the identification of the temperature range for a high-quality laser chemical machining of metals with the aim to increase the process control and reproducibility. Therefore, an analytical model to compute the laser induced temperature distributions is developed and verified. A subsequent correlation with the resulting removal geometries as well as performed high-speed shadowgraphs prove that a disturbance-free removal is initiated after exceeding the electrolyte boiling point and is limited by the occurrence of film boiling. Moreover, the removal velocity is primarily determined by the induced temperature gradients and the interaction time. In view of miniaturization, the comparison of defined geometric and qualitative machining features with those of micro electrochemical machining and micro milling reveals the suitability of laser chemical machining to manufacture metallic parts with dimensions < 1 mm³

Dynamic Process Behavior in Laser Chemical Micro Machining of Metals

Laser chemical machining (LCM) is a non-conventional processing method that enables a smooth and precise micro structuring of metallic surfaces. However, a high-quality removal is limited to a laser power window of some 100 mW. This is due to the high sensibility to removal disturbances, such as the deposition of metallic salts and oxides. In this work, the dynamic process behavior around the transition from a disturbance-free to a disturbed removal is investigated for the laser chemical machining of titanium (3.7024) and stainless steel (AISI 304) in different phosphoric acid solutions. Therefore, the removal cavities are recorded using confocal scanning microscopy and characterized regarding width, depth and quality in dependence of the laser power, feed velocity and electrolyte concentration. While the removal characteristics within the disturbance-free regime are found to be material-independent, the disturbed regime is strongly dependent on the tendency of the material to gas bubble adherence. Additional CCD records of the interaction zone reveal that the transition to the disturbed regime is accompanied by significant light reflections and thereby indicate the influence of adhering gas bubbles on disturbing the removal process. Moreover, typical removal disturbances are presented and discussed with regard to the responsible mechanisms for their occurrence

Précipitations et rendements du blé dur et de l'orge en culture «bour» dans le Maroc du Centre-ouest

The cereals production of the Western Centre of Morocco can double during certain years, mainly depending on the interannual variations of the yields that has been analysed here with regard to the impact of the rainfall variability. After regrouping precipitation totals into periods of two and three months, we have calculated the correlations between the annual yield of each province and the rainfall recorded at some meteorological stations for the same period. Among all the Western Centre provinces the variability of the annual rainfall totals turned out to have an influence on more than 50% in all the total yields variation. The January- February period always plays a major role.La part de la production céréalière du Centre-ouest dans la production marocaine oscille du simple au double selon les années en fonction essentiellement de la variation interannuelle des rendements qui est analysée ici en relation avec l'influence de la variabilité des précipitations. Après regroupements des totaux mensuels de pluies en bimestres et trimestres, nous avons procédé à une série de corrélations deux à deux entre les rendements annuels de chaque Direction Provinciale de l'Agriculture (DPA) et les précipitations de chacune des stations météorologiques retenues pour la même période. Dans toutes les DPA du Centre-ouest, plus de la moitié des variations des rendements est influencée par la variabilité des totaux annuels des pluies. Le bimestre de janvier-février joue toujours un rôle prépondérant.Douguedroit Annick, Durbiano Claudine, Messaoudi Abdelrhafour, Aït Hamza Mohamed. Précipitations et rendements du blé dur et de l'orge en culture «bour» dans le Maroc du Centre-ouest. In: Méditerranée, tome 88, 1-1998. Précipitations et cultures céréalières dans le Centre-ouest du Maroc, sous la direction de Annick Douguedroit et Claudine Durbiano. pp. 39-44

Geometrical design of micro-textured DLC coatings toward lubricant-free metal forming

To achieve a stable and high wear resistive functional surface under dry sliding friction, the present study proposes micro-textured diamond like carbon coatings fabricated by ionized physical vapour deposition (I-PVD) using metallic masks. To clarify the optimized geometrical dimensions under dry sliding friction, geometrical conditions of textured array patterns are varied by using metallic masks with different circular hole array patterns fabricated by picosecond pulsed laser processing. The effect of texturing on friction and wear properties is evaluated by ball-on-disk type friction tests for the condition of a constant DLC-coverage per unit area. Thereby, textured DLC pattern with diameters of 50 μm, 100 μm and 150 μm are applied. Within the first 10,000 laps stable and lower coefficient of friction is obtained with the smallest diameters of 50 μm. However, at further rotation of more than 40,000 laps, the wear of the smaller diameters becomes more pronounced due to the increase of stress concentration at the edge of the structure. Based on these findings, geometrical design of micro-textured DLC coating is discussed with regard to the suppression of three-body ploughing and the prevention of stress concentration

Geometrical design of micro-textured DLC coatings toward lubricant-free metal forming

To achieve a stable and high wear resistive functional surface under dry sliding friction, the present study proposes micro-textured diamond like carbon coatings fabricated by ionized physical vapour deposition (I-PVD) using metallic masks. To clarify the optimized geometrical dimensions under dry sliding friction, geometrical conditions of textured array patterns are varied by using metallic masks with different circular hole array patterns fabricated by picosecond pulsed laser processing. The effect of texturing on friction and wear properties is evaluated by ball-on-disk type friction tests for the condition of a constant DLC-coverage per unit area. Thereby, textured DLC pattern with diameters of 50 μm, 100 μm and 150 μm are applied. Within the first 10,000 laps stable and lower coefficient of friction is obtained with the smallest diameters of 50 μm. However, at further rotation of more than 40,000 laps, the wear of the smaller diameters becomes more pronounced due to the increase of stress concentration at the edge of the structure. Based on these findings, geometrical design of micro-textured DLC coating is discussed with regard to the suppression of three-body ploughing and the prevention of stress concentration