Entropy in nuclear collisions

Data on the multiplicity of pions produced in nucleon-nucleon interactions and central collisions of identical nuclei are discussed using a statistical approach. It is argued that the suppression of the pion production observed at low energies (p _LAB <15>c per nucleon) is due to entropy transfer to baryons. The enhancement of the entropy production in central S+S collisions at 200 GeV/c per nucleon may be interpreted as manifestation of the increase, by a factor of about 3, of the effective number of degrees of freedom in the early stage of the collision.     

The role of the liquid interface agent in mechanical properties improvement of modified chalk filled polyolefins

On the basis of the experimental results described in detail in the following sections an explanation of the mechanism of liquid modifier in chalk filled PP action was proposed. After concluding that liquid modifier does not change the sample morphology and crystallinity it was stated that it facilitates filler particles translocation in polymer matrix during deformation. Such translocations are the necessary condition for saturation of volume increase of the sample due to void formation in the process of polymer filler separation preserving the sample from its premature fracture. The most important physicochemical parameter of liquid modifier seems to be its molecular weight. This parameter determines liquids ability to migrate in micropore structure arising under stress and thus to act as a cracking agent. The possibility of the importance of more efficient heat dissipation in the sample was shown indicating the role of better thermal contacts in the sample in the case of modified chalk used as a filler. Such picture of mechanism of liquid modifier action leads also to two important conclusions:

Due to polymer filler separation by means of liquid layer no further filler particles surface processing, as in some cases, is needed.

The method of modification can be easily generalized for other polymers especially other polyolefins [19], [20] as physicochemical requirements for liquid are known.

     

Chromatographic method for the isolation of active 40S and 60S subunits from rat liver polyribosomes

A rapid and simple procedure for isolation of 40S and 60S ribosomal subunits by ion-exchange column chromatography is described. The dissociated ribosomes can be separated and non-ribosomal proteins and low-molecular-weight substances removed. An assessment by physicochemical and functional criteria showed that the ribosomal subunits obtained are active and sufficiently homogeneous.     

Pion and strangeness puzzles

The dependence of pion and strangeness production on the number of participant nucleons and collision energy is discussed for central A+A collisions. A possible interpretation of the experimental results assuming transition to QGP is sketched within a simple statistical approach.     

Electroanalytical end-point determination of hydrolytic precipitation titrations of sulphate and oxalate

Summary Electroanalytical End-Point Determination of Hydrolytic Precipitation Titrations of Sulphate and OxalateThe possibilities of application of biamperometric and bipotentiometric end-point determination by means of various indicator electrodes are described. Several titrants were used. Best results were obtained with quinhydrone electrodes. Interference levels of several anions were established. The lowest concentration of oxalate and sulphate that can be determined is 5×10^–4 M.

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Zusammenfassung Die Anwendungsmöglichkeiten der biamperometrischen und bipotentiometrischen Endpunktbestimmung mittels verschiedener Indikatorelektroden wurden beschrieben. Es wurden einige Titranten benützt. Die besten Resultate wurden mit Chinhydronelektroden erhalten. Die störende Wirkung verschiedener Anionen wurde festgestellt. Die geringste bestimmbare Konzentration beider Anionen (Sulfat und Oxalat) ist 5·10^–4 M.

     

In vitro study of antibiotic effect on bacterial adherence to acrylic intraocular lenses

Implantation of artificial intraocular lenses into the eye during ophthalmic surgical procedures ensures an unliving surface on which bacterial pathogens may attach and form biofilms. Despite antibiotic treatment bacteria growing in biofilms might cause inflammation and serious complications. In this study the adhesive ability of 7 Staphylococcus aureus and 11 coagulase-negative Staphylococcus (CNS) strains to the surface of acrylic intraocular lenses had been examined by the ultrasonic method. In untreated cases adhesion of the S. aureus and CNS strains did not differ significantly. We could not demonstrate significant differences between the adhesive ability of the standard strains and the clinical isolates. In this study a single – 60 min long – antibiotic (ciprofloxacin and tobramycin) treatment had been applied, that correlate well with the single or intermittant antibiotic prophylaxis of patients. Ciprofloxacin administration was able to reduce significantly the number of attached cells on the surface of acrylic lenses both in the case of S. aureus and CNS strains. Dependence of the effect from concentration could also be demonstrated. Tobramycin treatment was able to inhibit significantly the attachment of S. aureus cells. Despite the debate on antibiotic prophylaxis we presented in our experiments that a single antibiotic administration can decrease the attachment of bacterial cells to the surface of acrylic intraocular lenses, and might be effective in the prevention of postoperative endophthalmitis, that is a rare but serious complication of ophthalmic surgery.