Model for random hydrolysis and end degradation of linear polysaccharides: application to the thermal treatment of mannan in solution

The kinetics for homogeneous hydrolysis of mannan was studied in a batch reactor at temps. from 160 to 220 Deg. A formate buffer ensured a pH of 3.8-4.0, measured at 25 Deg. Samples were analyzed for oligosaccharides at a d.p. of ?6 and also for the total amt. of mannose after acid hydrolysis. A math. model with 2 reactions, i.e., (1) random hydrolysis of the glucosidic bonds; and (2) degrdn. of the reducing end of the mol., describes accurately the time course of oligosaccharides. Optimized rate consts. follow closely an Arrhenius relationship, with the degrdn. having a higher activation energy (140 kJ/mol) than the hydrolysis (113 kJ/mol). The math. model has the advantage that prodn. of small mols. is independent of the initial chain-length distribution, as long as the av. initial chain length is some 5 times longer than the largest species measured. It can be applied to 1st-order depolymn. of other linear polymers with 1 link type in order to det. reaction rate consts. or make predictions about mol. wt. distribution on the base of known reaction rate consts. [on SciFinder (R)

I bet you feel safe! assessing cyclists’ subjective safety by objective scores

Feeling safe is a major issue for cyclists, and some potential cyclists are still deterred from using the bicycle because they feel too unsafe. Assessing the subjective safety of existing cycling infrastructures and locations can be done by questionnaires that show pictures of infrastructures and ask participants for their safety ratings. However, future cycling infrastructures should also be evaluated as safe even before they are implemented. Therefore, it is desirable to have a method that is able to predict safety from infrastructural information. This study aims to propose two different ways for such a method and to test both ways in a use case. We first developed two scores, namely the Repertory Grid (RG) Score and the FixMyBerlin (FMB) Score, which predict subjective safety from objective environmental information but use different data bases and different methodologies. In a second step, we validated these scores by comparing them to questionnaire ratings that evaluated cyclists’ subjective safety at 20 locations in the city of Braunschweig, Germany. Finally, we compared the two scores as well as the questionnaire ratings with objective safety measures, namely crash statistics, at the respective locations. The results show that the RG Score has a moderate agreement and the FMB Score has a fair agreement with the questionnaire ratings. All methods agree on the overall safety evaluation of various cycling facilities. However, the RG Score showed less variance in the safety ratings, whereas the FMB Score rated most locations more unsafe than the participants in the questionnaire. Interestingly, neither the scores nor the questionnaire ratings could sufficiently deduce the occurrence of a crash at one of the locations. The findings strengthen the importance of subjective safety as a construct independent of objective safety. Furthermore, they provide insights into aspects of subjective safety that can easily be measured by objective scores, and into aspects that are important for cyclists but were not yet covered by the scores. This study, therefore, provides a basis for future considerations and future evaluation methods to assess the subjective safety of cyclists

220 fs Er-Yb:glass laser mode-locked by a broadband low-loss Si/Ge saturable absorber

We demonstrate femtosecond performance of an ultra-broadband high-index-contrast saturable Bragg reflector consisting of a silicon/silicon-dioxide/germanium structure that is fully compatible with CMOS processing. This device offers a reflectivity bandwidth of over 700 nm and sub-picosecond recovery time of the saturable loss. It is used to achieve mode-locking of an Er-Yb:glass laser centered at 1540 nm, generating 220 fs pulses, with the broadest output spectrum to date

Beitrag zur Kenntnis der sogenannten fleckfurmigen Fettdegeneration des Sehnerven speziell bei der p anoph tairai e.

OPLADEN-RUG0

EFFECTS AND INTERACTIONS OF DELAYED SIDE-TONE AND AUDITORY FLUTTER

Abstract not availabl

Microgravimetric determination of polycondensation kinetics

The polycondensation of bis(ethylene glycol) terephthalate to poly(ethylene terephthalate) was investigated by thermogravimetric measurements at 260-300 Deg. A model is developed which enables to ext. the apparent kinetic parameters from the measured mass loss curves. Changing the height of the polymer layer from 0.03-2.10 mm shows an influence of mass transfer on the reaction rate. The efficiency of a Sb(III) catalyst was examd. [on SciFinder (R)

Oiseaux et dauphins sur un décor de l’insula 6 d’Avenches (Suisse)

Dans le cadre de leur formation en archéologie, les étudiants de l’université de Lausanne ont la possibilité de suivre un stage pratique afin d’acquérir la méthode de traitement des enduits peints fragmentaires. En 2016, six étudiants ont eu l’occasion de s’initier à la peinture murale provinciale romaine en travaillant sur des ensembles inédits provenant de la ville antique d’Aventicum. Le décor présenté dans cet article est composé de panneaux rouges encadrés de bandes bleues sur un fond noir richement orné de candélabres à ombelles en inter-panneaux. Les informations de fouilles et les rapprochements stylistiques concordent pour dater cette peinture entre la fin du Ier s. et le début du IIe s. p.C