Depletion forces between two spheres in a rod solution

We study the depletion interaction between spherical particles of radius R immersed in a dilute solution of rigid rods of length L. The computed interaction potential is, within numerical accuracy, exact for any value of L/R. In particular we find that for L of order R, the depth of the depletion well is smaller than the prediction of the Derjaguin approximation. Our results bring new light into the discussion on the lack of phase separation in colloidal mixtures of spheres and rods.Comment: 12 pages including figures. 5 eps figures. LaTeX with REVTe

Vesicles in solutions of hard rods

The surface free energy of ideal hard rods near curved hard surfaces is determined to second order in curvature for surfaces of general shape. In accordance with previous results for spherical and cylindrical surfaces it is found that this quantity is non-analytical when one of the principal curvatures changes signs. This prohibits writing it in the common Helfrich form. It is shown that the non-analytical terms are the same for any aspect ratio of the rods. These results are used to find the equilibrium shape of vesicles immersed in solutions of rod-like (colloidal) particles. The presence of the particles induces a change in the equilibrium shape and to a shift of the prolate-oblate transition in the vesicle phase diagram, which are calculated within the framework of the spontaneous curvature model. As a consequence of the special form of the energy contribution due to the rods these changes cannot be accounted for by a simple rescaling of the elastic constants of the vesicle as for solutions of spherical colloids or polymers.Comment: 11 pages, 7 figures, submitted to Phys. Rev.

The Influence of Organizational Trust and Organizational Mindfulness on ERP Systems Usage

This paper examines how organizational trust and organizational mindfulness shape enterprise resource planning (ERP) system usage. We focus on five dimensions of trust: competence, openness and honesty, concern for employees, reliability, and identification. Drawing on organizational trust and organizational mindfulness theories, we argue that perception of organizational trust among ERP users might explain ERP system usage. We also predict that organizational mindfulness among ERP users positively influences ERP system usage. Our study draws on a total of 231 questionnaires collected from ERP system users across the United States. The results suggest that organizational trust dimensions (namely, competence, concern for employees, and identification) affect ERP system usage. Consistent with the theory, the results also support the idea that organizational trust (i.e., competence, openness and honesty, concern for employees, and identification) create supportive infrastructure-enabling organizational mindfulness. Finally, the study shows key antecedents of organizational mindfulness and underscores the importance of organizational mindfulness as a way of encouraging ERP system usage

IT Capability and Digital Transformation: A Firm Performance Perspective

As emerging digital technologies and capabilities continue to dominate our economic landscape, organizations are facing increased scrutiny on how digital transformation can provide the mechanism for innovation and firm performance. Using resource-based view (RBV) framework, this research examines the mediating effects of digital transformation in the relationship between IT capability and firm performance. Empirical data collected from CIOs from US firms reveal that although IT capability positively influences firm performance, it is mediated by digital transformation. Furthermore, our findings show that digital transformation positively influences innovation and firm performance while innovation is reaffirmed as having a positive implication on firm performance

Rods Near Curved Surfaces and in Curved Boxes

We consider an ideal gas of infinitely rigid rods near a perfectly repulsive wall, and show that the interfacial tension of a surface with rods on one side is lower when the surface bends towards the rods. Surprisingly we find that rods on both sides of surfaces also lower the energy when the surface bends. We compute the partition functions of rods confined to spherical and cylindrical open shells, and conclude that spherical shells repel rods, whereas cylindrical shells (for thickness of the shell on the order of the rod-length) attract them. The role of flexibility is investigated by considering chains composed of two rigid segments.Comment: 39 pages including figures and tables. 12 eps figures. LaTeX with REVTe

Effect of Chromium (VI) on the Oxidation of Methylene Blue Dye by Fe3O4/ Chitosan Composite

لا تزال إزالة ايونات المعادن الثقيلة من أنظمة معالجة مياه الصرف الصناعي صعبة لأنها تحتوي على ملوثات عضوية. في هذه الدراسة، تم استخدام الهلاميات المائية المركبة الوظيفية مع نشاط تفاعل فنتون لتحلل الملوثات العضوية. تشكل جزيئات أوكسيد الحديد الثلاثي والكيتوسان والمواد الأخرى الهيدروجيل. العوامل المحتلفة التي أثرت على نشاط فنتون الضوئي. تشمل الأس الهيدروجيني وتركيز بيروكسيد الهيدروجين ودرجة الحرارة وفترة التعرض. تم استخدام مجهر القوة الذرية (AFM) لفحص مورفولوجيا المركب ومتوسط قطره. وجد انه بعد  60 دقيقة  من التعرض للأشعة الفوق البنفسجية، تسبب المتراكب المحضر في تدهور صبغة المثيل الأزرق بنسبة  92%  في غضون ذلك، بعد ساعة واحدة من الإشعاع، انخفضت نسبة الطلب على الأوكسجين  (COD)لتحطيم المحتوى الكاربوني إلى   6.1  ملغم/لتر .                                                                                                      Heavy metal ion removal from industrial wastewater treatment systems is still difficult because it contains organic contaminants. In this study, functional composite hydrogels with photo Fenton reaction activity were used to decompose organic contaminants. Fe3O4 Nanoparticle, chitosan (CS), and other materials make up the hydrogel. There are different factors that affected Photo-Fenton activity including (pH, H2O2 conc., temp., and exposure period). Atomic force microscopy was used to examine the morphology of the composite and its average diameter (AFM). After 60 minutes of exposure to UV radiation, CS/ Fe3O4 hydrogel composite had degraded methylene blue (M.B.) dye by 92 percent. In the meantime, following an 1hour of visible irradiation, COD (Chemical Oxygen Demand) dropped to 6.1 mg/l

Multi-period supplier selection under price uncertainty

Cataloged from PDF version of article.We consider a problem faced by a procurement manager who needs to purchase a large volume of multiple items over multiple periods from multiple suppliers that provide base prices and discounts. Discounts are contingent on meeting various conditions on total volume or spend, and some are tied to future realizations of random events that can be mutually verified. We formulate a scenario-based multi-stage stochastic optimization model that allows us to consider random events such as a drop in price because of the most favoured customer clauses, a price change in the spot market or a new discount offer. We propose certainty-equivalent heuristics and evaluate the regret of using them. We use our model for three bidding events of a large manufacturing company. The results show that considering most favored customer clauses in supplier offers may create substantial savings that may surpass the savings from regular discount offers

Entropic Interactions in Suspensions of Semi-Flexible Rods: Short-Range Effects of Flexibility

We compute the entropic interactions between two colloidal spheres immersed in a dilute suspension of semi-flexible rods. Our model treats the semi-flexible rod as a bent rod at fixed angle, set by the rod contour and persistence lengths. The entropic forces arising from this additional rotational degree of freedom are captured quantitatively by the model, and account for observations at short range in a recent experiment. Global fits to the interaction potential data suggest the persistence length of fd-virus is about two to three times smaller than the commonly used value of $2.2 \mu {m}$.Comment: 4 pages, 5 figures, submitted to PRE rapid communication

Membranes in rod solutions: a system with spontaneously broken symmetry

We consider a dilute solution of infinitely rigid rods near a curved, perfectly repulsive surface and study the contribution of the rod depletion layer to the bending elastic constants of membranes. We find that a spontaneous curvature state can be induced by exposure of BOTH sides of the membrane to a rod solution. A similar result applies for rigid disks with a diameter equal to the rod's length. We also study the confinement of rods in spherical and cylindrical repulsive shells. This helps elucidate a recent discussion on curvature effects in confined quantum mechanical and polymer systems.Comment: 10 pages, 2 figures, 1 table; submitted to PR

Social Norms as a Cost-Effective Measure of Managing Transport Demand: Evidence from an Experiment on the London Underground

Demand for public transport in cities has been and is projected to increase, putting existing transport networks under increasing strain. Nudging passengers to behave in certain ways through the creation of a salient social norm has the potential to be a cost-effective mechanism to manage transport demand. Transport for London (TfL) implemented in the second half of 2017 an experiment on one of its busiest metro train platforms. The platform surface was painted to highlight the exact location of the train doors once it comes to a full stop and to direct passengers to wait in parts of the platform that would not obstruct passengers from alighting from the train and leaving the platform. Drawing on millions of individual train waiting times, we estimate the effect of this intervention to change passenger behaviour on the platform on train waiting and delay times. We use different sets of assumptions about what the counterfactual change in waiting and delay times would have been in the absence of the intervention. The intervention has reduced train waiting times by up to 6.6%. This reduction came about mainly through reducing delay times of trains once they are delayed. The reductions tend to occur during peak traffic hours. The implied cost-savings amount to a return of £6 per £1 investment