Side reactions in the synthesis of triblock copolymers of nylon‐6 with telechelic oligomers

BACKGROUND: The polymerization of hexanelactam (HL) is complicated by numerous side reactions: chain transfer to monomer, termination of the polymer chain, exchange as transamidation and formation of β‐ketoimides and β‐ketoamides. The generation of by‐products and their effect on the anionic polymerization of HL in the bulk in the presence of functionalized tetrahydrofuran oligomers as polymeric activators (PACs) were investigated. RESULTS: In order to consider how side reactions influence the process of HL polymerization, qualitative and quantitative determination of the by‐products obtained and their exhaustion were carried out. An investigation of the polymerization kinetics and the formation of low molecular weight by‐products through the polymerization was performed. The products are further involved in the polymerization process and consumed until an equilibrium level is reached. The mechanism of their generation is discussed. These processes were followed during the first polymerization stage by means of gel permeation chromatography. A mechanism of by‐product formation and consumption is proposed. CONCLUSION: The investigation of the polymerization kinetics and the formation of low molecular weight by‐products through the polymerization has shown that the side reaction yields oligomeric HL‐based products. The products are further involved in the polymerization process and consumed until an equilibrium level is reached. The equilibrium values depend on the HL/PACs ratio. Copyright © 2008 Society of Chemical Industry     

Luteinizing hormone (LH) levels in male workers exposed to urban stressors

The aim of the study is to evaluate if occupational exposure to urban stressors could cause alterations in luteinizing hormone (LH) plasma levels in male traffic policemen vs. administrative staff of Municipal Police.After excluding the subjects with the main confounding factors, male traffic police and administrative staff of Municipal Police were matched by age, working life, body mass index (BMI), alcohol drinking habit, cigarette smoking habit and habitual consumption of Italian coffee.In 166 male traffic police mean LH values were significantly higher compared to 166 male administrative employees. The distribution of LH values in traffic police and in administrative employees was statistically significant.Our results suggest that recent exposure to urban stressors (chemical, physical and psycho-social) can alter the plasma concentration of LH. In agreement with our previous research, levels of plasma LH may be used as early biological markers, valuable for the group, used in occupational set before the appearance of the disease.     

In-line control of the lyophilization process. A gentle PAT approach using software sensors

A lyophilization process is usually only specified in terms of a ‘recipe’ (shelf temperature and chamber pressure vs. time); according to the recent PAT guidelines issued by FDA, there is the need to develop in-line tools to enable better monitoring and control freeze-drying. In this work an advanced Manometric Temperature Measurement approach, called DPE (Dynamic Parameters Estimation) is first presented, based on a detailed mathematical model. In alternative, the “smart vial” concept is proposed, a Kalman filter based observer allowing an almost continuous monitoring without probes physically inserted into the product. Results obtained for pharmaceutical products in vial in a small industrial prototype equipped with the DPE-based LyoDriver control software, are presented. The software is capable to determine the optimal shelf temperature for primary drying, ensuring the fastest drying time without overcoming the maximum allowable product temperature both in scouting and production cycles. Finally, the two complementary monitoring systems, the DPE and the “smart vial”, are combined in an even more robust hybrid control system.     

Effects of different production techniques on glass–alumina functionally graded materials

Glass–alumina functionally graded materials were obtained using two different methods: percolation, which was representative of natural transport based processes, and plasma spraying, which was representative of constructive processes. The specimens produced in this way were investigated to evaluate the effect of production techniques on the final microstructure and gradient, which, in turn, govern the properties and performances of the graded systems. Moreover, post-production heat treatments were performed in order to improve the reliability of the materials examined.     

Effect of storage on the phenolic content,volatile composition and colour of white wines from the varieties Zalema and Colombard

Different quality attributes and chemical components of wines change during storage as a function of a series of factors. Thus, in young white wines, changes in phenolics, that lead to modifications of their colour as a result of oxidation processes, are well-known. These reactions can also alter their volatile profile giving rise to the appearance of new aromas, which in some cases are undesirable. In this study we have carried out a thorough evaluation of the changes in the colour, volatiles and phenolics of Zalema and Colombard wines during 1 year of storage under different conditions of temperature and position. The phenolics and colour were more affected than was the volatiles profile and wines kept in the cold could be clearly distinguished from the others, whilst the position of the bottles onlt slightly affected the wines during storage. Results showed that the blending of Zalema wines with Colombard wines may be an appropriate means of enhancing the acidity of the former without dramatically affecting its character.     

Effects of air-drying temperature on the cell walls of kiwifruit processed at different stages of ripening

The effects of air-drying temperature on the cell wall components of three sets of fresh kiwifruits at different degrees of ripening, unripe, half-ripe and ripe samples, have been evaluated. The modifications affecting the physico-chemical properties of cell wall polysaccharides were largely dependent, not only on the air-drying temperature used (from 30 °C to 90 °C), but also on the initial stage of ripening of the processed kiwifruits. Thus, whereas in comparison with the fresh fruits, dehydrated unripe and half-ripe kiwifruits maintained their overall cell wall composition better, processed ripe kiwifruits seemed to be more sensitive to cell wall degradation/solubilisation. In fact, important losses of cell wall material (CWM), mainly pectins and, also, hemicelluloses, were detected in the riper kiwifruits when these samples were dehydrated at high temperature (up to 30% CWM losses when drying was carried out at 90 °C). Heating also promoted considerable modifications of the degree of methyl-esterification (DME) of pectins. In general, an increase in the DME corresponded to an increase in the degree of ripening of the processed samples, suggesting that methylated pectins exhibited a higher resistance to the degradation/solubilisation caused by heating. All these changes in composition were clearly reflected in the solubility and functional properties (FP) of processed CWMs. Hydration properties, swelling and water retention, and, in particular, the capacity to absorb lipids, were modified after processing. In general, CWMs from processed half-ripe kiwifruits exhibited the highest FP values. Overall, the study clearly reflects the importance of taking into consideration the stage of ripening of fruits in order to determine the final quality of CWMs, and therefore, the properties of the dietary fibre (DF) which could be obtained from processed kiwifruit samples.     

Brain Metabolic Profile after Intranasal vs. Intraperitoneal Clomipramine Treatment in Rats with Ultrasound Model of Depression

Background: Molecular mechanisms of depression remain unclear. The brain metabolome after antidepressant therapy is poorly understood and had not been performed for different routes of drug administration before the present study. Rats were exposed to chronic ultrasound stress and treated with intranasal and intraperitoneal clomipramine. We then analyzed 28 metabolites in the frontal cortex and hippocampus. Methods: Rats’ behavior was identified in such tests: social interaction, sucrose preference, forced swim, and Morris water maze. Metabolic analysis was performed with liquid chromatography. Results: After ultrasound stress pronounced depressive-like behavior, clomipramine had an equally antidepressant effect after intranasal and intraperitoneal administration on behavior. Ultrasound stress contributed to changes of the metabolomic pathways associated with pathophysiology of depression. Clomipramine affected global metabolome in frontal cortex and hippocampus in a different way that depended on the route of administration. Intranasal route was associated with more significant changes of metabolites composition in the frontal cortex compared to the control and ultrasound groups while the intraperitoneal route corresponded with more profound changes in hippocampal metabolome compared to other groups. Since far metabolic processes in the brain can change in many ways depending on different routes of administration, the antidepressant therapy should also be evaluated from this point of view.