Self-consistent field predictions for quenched spherical biocompatible triblock copolymer micelles

We have used the Scheutjens-Fleer self-consistent field (SF-SCF) method to predict the self-assembly of triblock copolymers with a solvophilic middle block and sufficiently long solvophobic outer blocks. We model copolymers consisting of polyethylene oxide (PEO) as solvophilic block and poly(lactic-co-glycolic) acid (PLGA) or poly({\ko}-caprolactone) (PCL) as solvophobic block. These copolymers form structurally quenched spherical micelles provided the solvophilic block is long enough. Predictions are calibrated on experimental data for micelles composed of PCL-PEO-PCL and PLGA-PEO-PLGA triblock copolymers prepared via the nanoprecipitation method. We establish effective interaction parameters that enable us to predict various micelle properties such as the hydrodynamic size, the aggregation number and the loading capacity of the micelles for hydrophobic species that are consistent with experimental finding.Comment: accepted for publication in Soft Matte

Управление финансовой устойчивостью и рентабельностью предприятия

Целью статьи является изучение значения управления финансовой устойчивостью и рентабельностью предприятия в современных условиях хозяйствования

Reciprocating friction and wear behavior of WC-Co based cemented carbides manufactured by electro-discharge machining

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Bone Tissue Response to Porous and Functionalized Titanium and Silica Based Coatings

Background: Topography and presence of bio-mimetic coatings are known to improve osseointegration. The objective of this study was to evaluate the bone regeneration potential of porous and osteogenic coatings. Methodology: Six-implants [Control (CTR); porous titanium coatings (T1, T2); thickened titanium (Ti) dioxide layer (TiO2); Amorphous Microporous Silica (AMS) and Bio-active Glass (BAG)] were implanted randomly in tibiae of 20-New Zealand white rabbits. The animals were sacrificed after 2 or 4 weeks. The samples were analyzed histologically and histomorphometrically. In the initial bone-free areas (bone regeneration areas (BRAs)), the bone area fraction (BAF) was evaluated in the whole cavity (500 mm, BAF-500), in the implant vicinity (100 mm, BAF-100) and further away (100–500 mm, BAF-400) from the implant. Bone-to-implant contact (BIC-BAA) was measured in the areas where the implants were installed in contact to the host bone (bone adaptation areas (BAAs)) to understand and compare the bone adaptation. Mixed models were used for statistical analysis. Principal Findings: After 2 weeks, the differences in BAF-500 for different surfaces were not significant (p.0.05). After 4 weeks, a higher BAF-500 was observed for BAG than CTR. BAF-100 for AMS was higher than BAG and BAF-400 for BAG was higher than CTR and AMS. For T1 and AMS, the bone regeneration was faster in the 100-mm compared to the 400-mm zone. BIC-BAA for AMS and BAG was lower after 4 than 2 weeks. After 4 weeks, BIC-BAA for BAG was lower than AMS and CTR. Conclusions: BAG is highly osteogenic at a distance from the implant. The porous titanium coatings didn’t stimulate bone regeneration but allowed bone growth into the pores. Although AMS didn’t stimulate higher bone response, it has a potential of faster bone growth in the vicinity compared to further away from the surface. BIC-BAA data were inconclusive to understand the bone adaptation.status: publishe

Existence of a Tribo-Modified Surface Layer on SBR Elastomers: Balance Between Formation and Wear of the Modified Layer

In most of the tribological contacts, the composition and tribological properties of the original interface will change during use. The tribo-films, with modified properties compared to the bulk, are dynamic structures that play a significant role in friction. The existence of a tribo-modified surface layer and its importance on the overall friction of elastomers has been shown both theoretically and experimentally before. The characteristics of the modified surface layer deserve specific attention since the tribological properties of elastomers in contact with a rough counter-surface are determined by these modified surfaces together with the properties of bulk of the material. Both the formation of the modified layer and the break down (wear) of it are of importance in determining the existence and thickness of the tribo-modified layer. In this study, the importance of the wear is emphasized by comparing two styrene butadiene rubber-based elastomers in contact with a granite sphere. A current status of perception of the removal and the stability of the modified surface layers on rubbers is introduced as well as experimental work related to this matter and discussion within literature. Pin-on-disk friction tests are performed on two SBR-based samples in contact with a granite sphere under controlled environmental conditions to form the modified surface layer. Although the hysteresis part of the friction force which has a minor contribution in the overall friction is not markedly different, the total measured friction coefficient differs significantly. Mechanical changes both inside and outside the wear track are determined by atomic force microscope nano-indentations at different timescales to examine the modified surface layer on the test samples. The specific wear rates of the two tribo-systems are compared, and the existence of the modified surface layer, the different measured friction coefficient and the running-in distances toward steady-state friction are explained considering different wear rates. A conceptual model is presented, correlating the energy input into the tribo-system and the existence of a modified surface layer

Fitting in: A temporal perspective on experiences of person-environment fit in the workplace.

Since the publication of Lewin's equation B = f(P, E), which defines human behavior (B) as a function of both person (P) and environment (E) (Lewin, 1951), and the introduction of the term Person-Environment fit (P-E fit) by French and colleagues in 1974 (French et al., 1974), the concept of P-E fit evolved to one of the most widely used constructs in industrial psychology and human resource management. Over the past two decades, considerable research attention has been devoted to the study of P-E fit, which has produced important insights into the relationship between fit and a wide array of affective, attitudinal, and behavioral outcomes (Kristof-Brown et al., 2005). However, an important weakness of our understanding of P-E fit is that we still know very little about people's subjective experience of fit and misfit (Kristof-Brown & Billsberry, 2013). In this respect, Billsberry and colleagues recently argued that P-E fit theory should be divided into two inherently different portrayals of fit, i.e., an objective fit paradigm that focuses on the interaction or interplay between personal and environmental characteristics, and a perceived fit paradigm that focusses on the subjective experience of (not) fitting in (Edwards & Billsberry, 2010; Kristof-Brown & Billsberry, 2013). Of these two paradigms, the perceived fit paradigm remains severely under explored, and scholars have yet to clarify the exact meaning of perceived fit. In particular, we lack understanding about how these perceptions of fit and misfit develop and change over time, and why they influence our attitudes, thoughts, and behavior the way they do (Kristof-Brown & Billsberry, 2013). What we do know, however, is that employees are mostly influenced by their fit with the environment as they perceive it. In this respect, and compared to objective fit, perceived fit is commonly found to be a stronger predictor of employee outcomes like e.g. job satisfaction, commitment, performance and turnover (Hoffman, & Woehr, 2006; Kristof-Brown et al., 2005). Therefore, gaining insights in employees' perceptions of fit is crucial in understanding its organizational implications, including the management of fit and the benefits and drawbacks associated with fit and misfit (Billsberry et al., 2005). The main goal of my PhD is to provide insight into the nature of perceived fit, i.e., what perceived fit actually represents, how these perceptions form, and why they change over time.status: publishe