Nondegradative microextrusion of resorbable polyesters for pharmaceutical and biomedical applications: The cases of poly‐lactic‐acid and poly‐caprolactone

In recent years biodegradable polymers, particularly polyesters such as the poly(lactic acid) (PLA) and polycaprolactone (PCL), have gained high interests for their applicability in the biomedical and pharmaceutical fields where they're used for manufacturing various different resorbable devices, from tissue engineering scaffolds to controlled drug release systems. Despite many positive characteristics, processability of these materials still remains a critical issue as they easily tend to degrade during manufacturing. In this article we aimed to assess microextrusion as a nondegradative process for manufacturing PLA and PCL. The results we experimentally obtained, that are hereby presented, set a new point in the on‐going debate on degradation during processing of resorbable polymers as they allow to affirm that microextrusion leaves unmodified molecular weight distributions without producing any evident reductions in mean molecular weight. Microextrusion thus represents a risk‐free high molecular weight polymer processing solution for obtaining nondegraded products within pharmaceutical and biomedical production lines, such as for scaffolds for tissue engineering applications or drug delivery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Ergodicity of filtering process by vanishing discount approach

A new approach to study ergodicity of filtering processes is presented. It is based on the vanishing discount approach to discounted functional of filtering process. We show that limit superior of the Cesaro averages of the functionals is the same for all initial conditions from which the uniqueness of invariant measures of filtering processes follows. The approach is based on certain assumption for which we provide a sufficient condition using concavity arguments. In addition we show the existence of solutions to the Poisson equation corresponding to filtering process with concave functional. The assumptions are then extended to the controlled case and using similar concave arguments we obtain the existence of solutions to the Bellman equation corresponding to partially observed average cost per unit time problem.     

Constructed wetland as a low cost and sustainable solution for wastewater treatment adapted to rural settlements: the Chorfech wastewater treatment pilot plant

The paper presents the detailed design and some preliminary results obtained from a study regarding a wastewater treatment pilot plant (WWTPP), serving as a multistage constructed wetland (CW) located at the rural settlement of 'Chorfech 24' (Tunisia). The WWTPP implemented at Chorfech 24 is mainly designed as a demonstration of sustainable water management solutions (low-cost wastewater treatment), in order to prove the efficiency of these solutions working under real Tunisian conditions and ultimately allow the further spreading of the demonstrated techniques. The pilot activity also aims to help gain experience with the implemented techniques and to improve them when necessary to be recommended for wide application in rural settlements in Tunisia and similar situations worldwide. The selected WWTPP at Chorfech 24 (rural settlement of 50 houses counting 350 inhabitants) consists of one Imhoff tank for pre-treatment, and three stages in series: as first stage a horizontal subsurface flow CW system, as second stage a subsurface vertical flow CW system, and a third horizontal flow CW. The sludge of the Imhoff tank is treated in a sludge composting bed. The performances of the different components as well as the whole treatment system were presented based on 3 months monitoring. The results shown in this paper are related to carbon, nitrogen and phosphorus removal as well as to reduction of micro-organisms. The mean overall removal rates of the Chorfech WWTPP during the monitored period have been, respectively, equal to 97% for total suspended solids and biochemical oxygen demand (BOD5), 95% for chemical oxygen demand, 71% for total nitrogen and 82% for P-PO4. The removal of E. coli by the whole system is 2.5 log units.     

驾驭电力

控制工程师也许会天真地认为,设备管理者会像变魔术般为他们搭建好的自动化系统提供数量充足、质量上乘的电能。但事实是,这些自动化系统很可能会打乱电力分配体系的平衡状态,并降低供电质量。同时,控制工程师时常会过分追求供电质量,从而心生报怨。     

运动控制建模

机械、电气以及软件工程的集成正在改变运动控制设计及其发展的面貌。基于自己在传统机器制造业中的经验,Rockwell Automation的Kinetix Motion Control Business产品市场经理John Pritchard说,"单独的机械、控制和电气设计小组进行独立的工作,生产整台机     

GANAB and N-Glycans Substrates Are Relevant in Human Physiology,Polycystic Pathology and Multiple Sclerosis: A Review

Glycans are one of the four fundamental macromolecular components of living matter, and they are highly regulated in the cell. Their functions are metabolic, structural and modulatory. In particular, ER resident N-glycans participate with the Glc₃Man₉GlcNAc₂ highly conserved sequence, in protein folding process, where the physiological balance between glycosylation/deglycosylation on the innermost glucose residue takes place, according GANAB/UGGT concentration ratio. However, under abnormal conditions, the cell adapts to the glucose availability by adopting an aerobic or anaerobic regimen of glycolysis, or to external stimuli through internal or external recognition patterns, so it responds to pathogenic noxa with unfolded protein response (UPR). UPR can affect Multiple Sclerosis (MS) and several neurological and metabolic diseases via the BiP stress sensor, resulting in ATF6, PERK and IRE1 activation. Furthermore, the abnormal GANAB expression has been observed in MS, systemic lupus erythematous, male germinal epithelium and predisposed highly replicating cells of the kidney tubules and bile ducts. The latter is the case of Polycystic Liver Disease (PCLD) and Polycystic Kidney Disease (PCKD), where genetically induced GANAB loss affects polycystin-1 (PC1) and polycystin-2 (PC2), resulting in altered protein quality control and cyst formation phenomenon. Our topics resume the role of glycans in cell physiology, highlighting the N-glycans one, as a substrate of GANAB, which is an emerging key molecule in MS and other human pathologies.     

The effect of nano-scale interaction forces on the premature pull-in of real-life Micro-Electro-Mechanical Systems

A new experimental device has been designed and produced with the purpose of investigating the possible effect of nano-scale interaction forces on the reliability issue related to pull-in of uncharged plates. This paper reports the outcomes of the experimental tests carried out on the aforementioned micro-structure, which presents the essential features of real-life MEMS and is produced using the same technology as standard commercial devices. The experiments show, with a high degree of repeatability, a premature failure of the structure, as a consequence of pull-in instability. The results of the tests are critically evaluated by comparison with theoretical predictions, in order to assess the role played by nano-scale interaction forces caused by, e.g., parasitic charging, contact and patch potentials, Casimir force.     

Sphaeropsidin A: A Pimarane Diterpene with Interesting Biological Activities and Promising Practical Applications

Sphaeropsidin A (SphA) is a tetracyclic pimarane diterpene, first isolated as the main phytotoxin produced by Diplodia cupressi the causal agent of a severe canker disease of Italian cypress (Cupressus sempervirens L.). It was also produced, together with several analogues, by different pathogenic Diplodia species and other fungi and showed a broad array of biological activities suggesting its promising application in agriculture and medicine. The anticancer activity of SphA is very potent and cell specific. Recent studies have revealed its unique mode of action. This minireview reports the structures of SphA and its family of natural analogues, their biosynthetic origins, their fungal sources, and biological activities. The preparation of various SphA derivatives is also described as well as the results of structure-activity relationship (SAR) studies and on their potential practical applications.     

Mechanochemical Processing of Mn and Co Oxides: An Alternative Way to Synthesize Mixed Spinels for Protective Coating

High‐Energy Ball Milling (HEBM) is proposed as a cost effective and environmental friendly technique to produce Co‐ and Mn‐ based oxides suitable for application as protective coating. Mixtures of manganese and cobalt oxides in different molar ratio (Co:Mn = 1:1 and Co:Mn = 2:1) were subjected to mechanochemical treatment up to 100 h and morpho‐structural evolution was evaluated. XRD analysis results show that the HEBM treatment promotes the solid‐state reaction of the starting compounds, with the formation of different crystalline phases when compared to high‐temperature solid‐state synthesis. SEM observations and N₂ adsorption measurements suggest that all processed powders are composed by aggregates of nanometric particles. While long milling time is required to complete the reaction, 10 hours are enough to activate the powders to obtain the desired phases after a mild thermal treatment, as evidenced by in situ thermal XRD analysis. Electrical conductivity measures performed with the Van der Pauw method on sintered pellets evidence a significant difference between the two compositions, related to the dual‐phase nature of Co:Mn = 1:1 material at intermediate temperatures (i.e., T < 700°C), Co:Mn = 2:1 sample showing higher conductivity values in the whole tested range (500°C–800°C).