Styrene-divinylbenzene copolymers. Construction of porosity in styrene divinylbenzene matrices

Experimental data are presented describing the formation of porosity in styrene-divinylbenzene copolymers as a function of the organic components present during the suspension polymerization. The reaction system contains a mixture of diluents such as toluene and hexane, which results in matrices that differ significantly in pore structure from the porous resins so far known. From these data a model of the physical structure is proposed

Styrene-divinylbenzene copolymers. II. The conservation of porosity in styrene-divinylbenzene copolymer matrices and derived ion-exchange resins

The collapse of pores in styrene-divinylbenzene copolymers and corresponding ion-exchange resins was studied during the removal of solvating liquids. The process can be followed in a most simple way by measuring the volume of the bead-shaped copolymers upon drying. Other parameters observed during drying were the apparent density and incidently the internal surface. The collapse of pores is considered to be a result of cohesional forces when solvated polymer chains are approaching each other by loss of solvent. The effect will thus be more pronounced in gel-type networks than in porous ones. In porous networks, the effect will be stronger in smaller pores than in larger ones. It is shown that crosslinks, increasing the rigidity of the structures, will favor the conservation of porosity. In ion-exchange resins the pore stability is best when the material is in its lowest state of hydration. Generally, the collapse of pores is a reversible process. The collapsed material can in most cases be reswollen by the proper choice of solvent

The asymptotic regimes of tilted Bianchi II cosmologies

In this paper we give, for the first time, a complete description of the dynamics of tilted spatially homogeneous cosmologies of Bianchi type II. The source is assumed to be a perfect fluid with equation of state $p = (\gamma -1) \mu$, where $\gamma$ is a constant. We show that unless the perfect fluid is stiff, the tilt destabilizes the Kasner solutions, leading to a Mixmaster-like initial singularity, with the tilt being dynamically significant. At late times the tilt becomes dynamically negligible unless the equation of state parameter satisfies $\gamma > {10/7}$. We also find that the tilt does not destabilize the flat FL model, with the result that the presence of tilt increases the likelihood of intermediate isotropization

Accepting or declining dialysis: considerations taken into account by elderly patients with end-stage renal disease

BACKGROUND: Elderly patients with end-stage renal disease have to make a difficult decision whether or not to start dialysis. This study explores the considerations taken into account by these patients in decision-making regarding renal replacement therapy. METHOD: In-depth interviews were conducted to gain an enhanced understanding of the considerations in treatment decision-making. Fourteen patients aged 65 years or older participated in the interviews, of whom 8 patients had made the decision to start, and 6 patients the decision to decline, dialysis. RESULTS: All participating patients had a variety of health problems, but appeared to have normal cognitive functions. Patients who declined dialysis were older and more often men and widow(er)s compared with patients who accepted dialysis. Patients chose to start dialysis because they enjoyed life, were not prepared to face the end of life, felt they had no other choice or had care-giving responsibilities for family members. Patients declined dialysis because of the speculated loss of autonomy, their age-associated decrease in vitality, distance from dialysis center and reluctance to think about the future. CONCLUSION: Results suggest that patients' decisions to decline or accept dialysis are not based on the effectiveness of the treatment, but rather on personal values, beliefs and feelings toward life, suffering and death, and the expected difficulties in fitting the treatment into their life

Differences between physicians in the likelihood of referral and acceptance of elderly patients for dialysis-influence of age and comorbidity

BACKGROUND: Incidence of dialysis in elderly patients in the Netherlands is low compared to other countries. This study aims to assess the impact of patients' age and comorbidity on the likelihood of referral and acceptance of patients for dialysis and whether this is affected by physician characteristics. METHODS: A vignette study was performed among 209 primary care physicians, 162 non-nephrology specialists and 20 nephrologists working in the north of the Netherlands. Physicians were offered six vignettes concerning case-reports of patients with end-stage renal disease (ESRD) and varying comorbidities or circumstances and asked about the likelihood of referral/acceptance of the patient in the given circumstances. RESULTS: The likelihood of referral within groups of physicians varied widely, especially within the group of primary care physicians and non-nephrology specialists, but was not affected by characteristics of physicians. The likelihood of referral or acceptance of patients for dialysis depended on the patient's age, and type and severity of comorbidity. In general, primary care physicians and non-nephrology specialists were less likely to refer than nephrologists were to accept. Differences within and between groups of physicians were larger for 80- than for 65-year-old patients, and for patients with less severe shortness of breath and cognitive impairments and more severe diabetes and social impairments. Hardly any differences were found for patients with cancer. CONCLUSION: Patients' age and comorbidities affect the likelihood of referral. Differences between groups of physicians suggest that there is insufficient agreement on the extent to which these factors should affect the referral/acceptance of patients for dialysis. These findings underline the need for more research into circumstances under which patients might benefit from dialysis. Guidelines should be developed to improve the referral of elderly and less healthy patients

Applying prosodic speech features in mental health care: An exploratory study in a life-review intervention for depression

The present study aims to investigate the application of prosodic speech features in a psychological intervention based on lifereview. Several studies have shown that speech features can be used as indicators of depression severity, but these studies are mainly based on controlled speech recording tasks instead of natural conversations. The present exploratory study investigated speech features as indicators of depression in conversations of a therapeutic intervention. The changes in the prosodic speech features pitch, duration of pauses, and total duration of the participant's speaking time were studied over four sessions of a life-review intervention for three older participants. The ecological validity of the dynamics observed for prosodic speech features could not be established in the present study. The changes in speech features differed from what can be expected in an intervention that is effective in decreasing depression and were inconsistent with each other for each of the participants. We suggest future research to investigate changes within the intervention sessions, to relate the changes in feature values to the topical content of the speech, and to relate the speech features directly to depression scores

On order policies with pre-specified order schedules for a perishable product in retail.

This paper studies a retail inventory system for a perishable product, based on a practical setting in Dutch retail. The product has a fixed shelf life of three days upon delivery at the store and product demand has a weekly pattern, which is stationary over the weeks, but varies over the days of the week. Items of varying age occur in stock. However, in retail practice, the age-distribution is often unknown, which complicates order decisions. Depending on the type of product or the size of the supermarket, replenishment cycle lengths may vary. We study a situation where a store is replenished either three or four times a week on pre-specified days. The research aim is to find practical and efficient order policies that can deal with the lack of information about the age distribution of items in stock, considering mixed LIFO and FIFO withdrawal. Reducing potential waste goes along with cost minimization, while the retailer aims at meeting a cycle service level requirement. We present four new heuristics that do not require knowledge of the inventory age-distribution. A heuristic, based on a constant order quantity for each order moment, often generates least waste and lowest costs. However, this requires a few minutes of computation time. A new base stock policy appears second best

Прогноз глобальних тенденцій релігійних змін у світі ХХІ століття та їхніх імплікацій в українському контексті

Drug purity and affinity are essential attributes during development and production of therapeutic proteins. In this work, capillary electrophoresis (CE) was used to determine both the affinity and composition of the biotechnologically produced "nanobody" EGa1, the binding fragment of a heavy-chain-only antibody. EGa1 is an antagonist of the epidermal growth factor receptor (EGFR), which is overexpressed on the surface of tumor cells. Using a background electrolyte (BGE) of 50mM sodium phosphate (pH 8.0) in combination with a polybrene-poly(vinylsulfonic acid) capillary coating, CE analysis of EGa1 showed the presence of at least three components. Affinity of the EGa1 components towards the extracellular domain of EGFR was assessed by adding different concentrations (0-12nM) of the receptor to the BGE while measuring the effective electrophoretic mobility of the respective EGa1 components. Binding curves obtained by plotting electrophoretic mobility shifts as a function of receptor concentration, yielded dissociation constants (

Socially-mediated changes in brain epigenome in the fire ant

Herein, we report a robust way for the formation of biodegradable poly(ethylene glycol)-block-poly(e-caprolactone) (PEG-b-PCL) polymersomes, via direct hydration of a highly concentrated block copolymer/oligo(ethylene glycol) solution. Polymersomes with variable membrane thickness were formed under relatively mild conditions in a short time, by changing the hydrophobic block length. Plunge freezing followed by cryo transmission electron microscopy (Cryo-TEM) was utilized to visualize the morphology of newly-formed polymersomes in their native condition. An MTT cytotoxicity study showed that the as-prepared polymersomes have good biocompatibility to hCMEC/D3 brain endothelial cells. As this method does not involve the use of small molecular organic solvent, sonication or freeze-thawing steps, it can offer the opportunity to form biodegradable polymersomes on-site. The work may facilitate the bench-to-bedside translation of biodegradable polymersomes as robust drug nanocarriers