Pseudopolymorphic transitions of niclosamide monitored by Raman spectroscopy

Niclosamide suffers pseudopolymorphic transformations when exposed to different ambient conditions, which can lead to changes in its bioavailability. In this study, the kinetics of the pseudopolymorphic transitions of niclosamide crystals are characterized. FT-Raman spectroscopy is used to quantify the anhydrate and hydrate forms of niclosamide crystals, mostly because of its high sensitivity to the strong intermolecular interactions present in these systems. The samples are exposed to well-characterized relative humidity (RH) conditions during different periods of time and both water diffusion and polymorphic changes are monitored from the corresponding changes observed in the vibrational spectra. Both hydration and dehydration were found to be single-step processes, with a half-life time of ca. 142 and 63 h, respectively, at 24 °C. Copyright © 2008 John Wiley & Sons, Ltd

Quantitative plane-resolved crystal growth and dissolution kinetics by coupling in situ optical microscopy and diffusion models : the case of salicylic acid in aqueous solution

The growth and dissolution kinetics of salicylic acid crystals are investigated in situ by focusing on individual microscale crystals. From a combination of optical microscopy and finite element method (FEM) modeling, it was possible to obtain a detailed quantitative picture of dissolution and growth dynamics for individual crystal faces. The approach uses real-time in situ growth and dissolution data (crystal size and shape as a function of time) to parametrize a FEM model incorporating surface kinetics and bulk to surface diffusion, from which concentration distributions and fluxes are obtained directly. It was found that the (001) face showed strong mass transport (diffusion) controlled behavior with an average surface concentration close to the solubility value during growth and dissolution over a wide range of bulk saturation levels. The (1̅10) and (110) faces exhibited mixed mass transport/surface controlled behavior, but with a strong diffusive component. As crystals became relatively large, they tended to exhibit peculiar hollow structures in the end (001) face, observed by interferometry and optical microscopy. Such features have been reported in a number of crystals, but there has not been a satisfactory explanation for their origin. The mass transport simulations indicate that there is a large difference in flux across the crystal surface, with high values at the edge of the (001) face compared to the center, and this flux has to be redistributed across the (001) surface. As the crystal grows, the redistribution process evidently can not be maintained so that the edges grow at the expense of the center, ultimately creating high index internal structures. At later times, we postulate that these high energy faces, starved of material from solution, dissolve and the extra flux of salicylic acid causes the voids to close

Anatomical Differences across Cerebellar Neuronal Networks in Valproic Acid (VPA) Induced Rats

The cortico-cerebellar circuits are highly involved in the coordination of sensorimotor processes and are crucial for the expression of sensorimotor and, with more recent literature, cognitively demanding behaviors in early childhood. Through these circuits, cerebellar differences could impact behavioral changes characterized in many neurological disorders, including Autism Spectrum Disorder (ASD). Despite the increasing prevalence of the disorder, insights into the anatomical differences across cerebellar neuronal networks in ASD remain poorly understood. The objective of this thesis is to characterize the cerebellar circuitry in a valproic acid (VPA)-induced animal model of ASD. Tissues were stained with Cresyl violet and captured with a confocal microscope. First, we examined the counts in (1) Purkinje cell (PC) and (2) Deep cerebellar nuclei (DCN) cells while measuring their density. Consistent with our hypothesis, we found that there were: (1) significant losses in PC density in the posterior inferior regions of lobules Crus I, Crus II, PM, and Cop of the hemisphere, and (2) significantly higher DCN density of the medial nuclei, contrary to our hypothesis, in the VPA-exposed rats compared to the control. Then, we examined the granule cell layer (GCL) thickness measurements across the lobules of the vermis and hemisphere and found that GCL thickness of Lobule 6 was lower, while Lobule 7-8-9 and Lobule 10 were higher in the VPA-exposed rats compared to control. Finally, we found a correlation and cross-covariance between the PC and GCL thickness measurements in the lobules of the posterior lobe. These findings suggest alterations in cerebellar anatomy affected by the VPA, and therefore further support the implication of the cerebellum and cerebellar circuits in VPA-exposed rats

Euphoria in financial markets: how Indian companies generate value in their cross-border acquisitions

In this paper, we investigate the effect of euphoria on returns derived by Indian companies in their cross-border acquisitions. Cognitive legitimacy generated at the country level facilitated firms in deriving higher value from internationalization. In addition, overoptimism after the legitimacy-building event led to euphoria in financial markets and short-term abnormal returns. Hence we argue that the springboard effect created by legitimacy is short-lived, as euphoria fades away over time. Using cross-border and domestic acquisitions by Indian companies during 1999-2009, and controlling for fundamental factors, both financial and non-financial, we find support for our euphoria hypothesis. Because of overoptimism, Indian companies experienced short-term abnormal returns in their cross-border acquisitions in the few years following the legitimation process, but not in later years

Risk propensity in the foreign direct investment location decision of emerging multinationals

A distinguishing feature of emerging economy multinationals is their apparent tolerance for host country institutional risk. Employing behavioral decision theory and quasi-experimental data, we find that managers’ domestic experience satisfaction increases their relative risk propensity regarding controllable risk (legally protectable loss), but decreases their tendency to accept non-controllable risk (e.g., political instability). In contrast, firms’ potential slack reduces relative risk propensity regarding controllable risk, yet amplifies the tendency to take non-controllable risk. We suggest that these counterbalancing effects might help explain observation that risk-taking in FDI location decisions is influenced by firm experience and context. The study provides a new understanding of why firms exhibit heterogeneous responses to host country risks, and the varying effects of institutions

Foreign vs domestic ownership on debt reduction: an investigation of acquisition targets in Italy and Spain

This paper examines the role of foreign versus domestic ownership in reducing the debt levels of acquired firms in Italy and Spain over the period 2002–2010. Acknowledging that lower debt levels can mitigate the risk of failure and thus enhance the chances for a positive post-acquisition performance and survival, we particularly examine the causal effect of foreign and domestic acquisitions on two firm-level debt measures: gearing and short-term leverage. To estimate causal relationships, we control for selection bias by applying propensity score matching techniques. Our results indicate that foreign acquisition leads to a significant and steady reduction in the debt ratios of the target companies. In contrast, the relationship between domestic acquisition and debt reduction appears to be smaller and statistically less robust