Diffusive-to-ballistic transition in dynamic light transmission through thin scattering slabs: a radiative transfer approach

We study the deviation from diffusion theory that occurs in the dynamic transport of light through thin scattering slabs. Solving numerically the time-dependent radiative transfer equation, we obtain the decay time and the effective diffusion coefficient Deff. We observe a nondiffusive behavior for systems whose thickness L is smaller than 8l(tr), where l(tr) is the transport mean free path. We introduce a simple model that yields the position of the transition between the diffusive and the nondiffusive regimes. The size dependence of Deff in the nondiffusive region is strongly affected by internal reflections. We show that the reduction of approximately 50% of Deff that was observed experimentally [Phys. Rev. Lett. 79, 4369 (1997)] can be reproduced by the radiative transfer approach. We demonstrate that the radiative transfer equation is an appropriate tool for studying dynamic light transport in thin scattering systems when coherent effects play no significant role.     

Skeletal Optimization of Cytotoxic Lipidic Dialkynylcarbinols

In line with a recent study of the pharmacological potential of bioinspired synthetic acetylenic lipids, after identification of the terminal dialkynylcarbinol (DAC) and butadiynyl alkynylcarbinol (BAC) moieties as functional antitumor pharmacophoric units, this work specifically addresses the issue of carbon backbone length. A systematic variation of the aliphatic chain length was thus carried out in both the DAC and BAC series. The critical impact of the length of the lipidic skeleton was first confirmed in the racemic series, with the highest cytotoxic activity observed for C₁₇ to C₁₈ backbones. Enantiomerically enriched samples were prepared by asymmetric synthesis of the optimal C₁₈ DAC and C₁₇ BAC derivatives. Samples with upgraded enantiomeric purity were alternatively produced by enzymatic kinetic resolution. Eutomers possessing the S configuration displayed cytotoxicity IC₅₀ values as low as 15 nm against HCT116 cancer cells, the highest level of activity reached to date in this series.     

On the Efficiency of a VR Hand Gesture-Based Interface for 3D Object Manipulations in Conceptual Design

In the early stages of 3D design, sketches are used to quickly conceptualize ideas and gain insight into problems and possible solutions. Computer-aided design tools are widely used for 3D modeling and design, but their required precision and 2D mouse and screen-based interface inhibit the flow of ideas. A study was conducted to explore the efficiency of hand tracking and virtual reality (VR) for 3D object manipulations in conceptual design. Based on existing research on conceptual design and hand gestures, an intuitive hand-based interaction model is proposed. An experiment on basic 3D manipulation shows that participants using a simple VR and hand-tracking interface prototype have similar performance to those using a traditional mouse and screen interface. For the improvement of gestural conceptual design interfaces, the relevant issues are identified.     

Semantic web-based social network access control

The existence of online social networks that include person specific information creates interesting opportunities for various applications ranging from marketing to community organization. On the other hand, security and privacy concerns need to be addressed for creating such applications. Improving social network access control systems appears as the first step toward addressing the existing security and privacy concerns related to online social networks. To address some of the current limitations, we have created an experimental social network using synthetic data which we then use to test the efficacy of the semantic reasoning based approaches we have previously suggested.     

A Microfluidic Platform to Monitor Real-Time Effects of Extracellular Vesicle Exchange between Co-Cultured Cells across Selectively Permeable Barriers

Exosomes and other extracellular vesicles (EVs) play a significant yet poorly understood role in cell–cell communication during homeostasis and various pathological conditions. Conventional in vitro and in vivo approaches for studying exosome/EV function depend on time-consuming and expensive vesicle purification methods to obtain sufficient vesicle populations. Moreover, the existence of various EV subtypes with distinct functional characteristics and submicron size makes their analysis challenging. To help address these challenges, we present here a unique chip-based approach for real-time monitoring of cellular EV exchange between physically separated cell populations. The extracellular matrix (ECM)-mimicking Matrigel is used to physically separate cell populations confined within microchannels, and mimics tissue environments to enable direct study of exosome/EV function. The submicron effective pore size of the Matrigel allows for the selective diffusion of only exosomes and other smaller EVs, in addition to soluble factors, between co-cultured cell populations. Furthermore, the use of PEGDA hydrogel with a very small pore size of 1.2 nm in lieu of Matrigel allows us to block EV migration and, therefore, differentiate EV effects from effects that may be mediated by soluble factors. This versatile platform bridges purely in vitro and in vivo assays by enabling studies of EV-mediated cellular crosstalk under physiologically relevant conditions, enabling future exosome/EV investigations across multiple disciplines through real-time monitoring of vesicle exchange.     

Synthesis and characterization of novel benzhydrol-containing poly(amide-imide)s

A series of novel benzhydrol-containing poly(amide-imide)s (PAIs) have been prepared from a new diimide-dicarboxylic acid, N,N′-bis(4-hydroxycarbonyl)-benzhydrol-3,3′,4,4′-tetracarboxydiimide (BHTDA-DIA), with various diamines by direct polycondensation using triphenyl phosphite and pyridine as condensing agents. The polymers obtained had inherent viscosities of 0.35–0.96 dl g⁻¹. All these PAIs, except polymer PAI-2, were soluble in N-methyl-2-pyrrolidinone and N,N-dimethylacetamide containing LiCl (1 wt%). Tough and flexible PAI films could be obtained by casting PAIs from their DMAc or NMP solutions, except for polymer PAI-2. The polymer films had a tensile strength of 93–111 MPa, an elongation at break range of 4–6%, and an initial modulus range of 2.7–3.8 GPa. The glass transition temperatures of most polymers were found to be above 255 °C. These polymers were fairly stable up to a temperature around or above 400 °C, and lost 10% weight in the range 426–507 °C in nitrogen and 423–515 °C in air. © 1999 Society of Chemical Industry     

Magnetic resonance imaging study of complex flow of viscoelastic fluids

NMR imaging techniques have been applied to investigate complex fluid dynamics in pipes and in annular flow conditions. In this application, aimed to simulate drilling and production operations, two lines have been set up to reproduce, at small laboratory scale, respectively, a pipe flow and an annular flow that are typical flow geometries in oilfield wells during drilling. NMR imaging measurements have been performed inside a horizontal‐bore magnet with a fluid flow assured in a velocity range of 10–100 cm s^?1. The studies were dedicated to investigate the different flow regimes associated to circulating viscous polymer solutions applied in drilling mud formulations. Early transitions from laminar to turbulent regime were observed at very low Reynolds number (in a range between 300 and 500, to be compared with the theoretical transition value greater than 2100). © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Effect of treatment with simvastatin on bone microarchitecture of the femoral head in an osteoporosis animal model

The objective of this study was to evaluate the microarchitecture and trabecular bone strength at the distal region of the femur, and its biomechanical properties with simvastatin administration with two different doses in ovariectomized (OVX) rats. Ninety rats were divided into six groups to evaluate treatment with the simvastatin drug (n = 15): SH (Sham surgery), SH‐5 (5 mg simvastatin), SH‐20 (20 mg simvastatin), OVX, OVX‐5, and OVX‐20. Euthanasia was performed at three different times, five animals per period: 7, 14, and 28 days. The effectiveness of the treatments was evaluated by mechanical testing and histomorphometric analysis of the femurs. The results of analysis by the linear model of mixed effects showed 20 mg of simvastatin results in increased trabecular bone after 14 days (P = 0.039) of ingestion in ovariectomized animals. However, ingestion of 5 mg of simvastatin is able to sensitize the trabecular bone only at 28 days (P = 0.005) of ingestion. In the mechanical tests stiffness improves within 28 days (P = 0.003). Regarding maximum strength, no statistical differences were observed. According to these results, it can be concluded that for a decrease in oral intake, longer treatment times are required. Microsc. Res. Tech. 79:684–690, 2016. © 2016 Wiley Periodicals, Inc.     

"The developmental interference between nature and nurture: A mutual influence model of child antisocial behavior and parent behaviors": Erratum.

Reports an error in the original article by X. Ge et al (Developmental Psychology, 1996 [Jul], Vol 32[4], 574–589). On page 584, Figure 2, negative signs were mistakenly inserted in front of 2 coefficients. The correct coefficients are given. (The following abstract of this article originally appeared in record 1996-01781-002.). Using an adoption design to collect data on biological and adoptive parents of children adopted at birth, this study explored a possible mechanism through which heritable characteristics of adopted children evoke adoptive parent responses and lead to reciprocal influences between adoptive parent and adopted child behavior. Participants were 25 male and 20 female adoptees, 12–18 years of age, having either a biological parent with substance abuse/dependency or antisocial personality or a biological parent with no such history. The study found that psychiatric disorders of biological parents were significantly related to children's antisocial/hostile behaviors and that biological parents' psychiatric disorders were associated with adoptive parents' behaviors. This genotype-environment association was largely mediated by adoptees' antisocial/hostile behaviors. Results also suggest that the adoptee's antisocial/hostile behavior and adoptive… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The developmental interface between nature and nurture: A mutual influence model of child antisocial behavior and parent behaviors.

Using an adoption design to collect data on biological and adoptive parents of children adopted at birth, this study explored a possible mechanism through which heritable characteristics of adopted children evoke adoptive parent responses and lead to reciprocal influences between adoptive parent and adopted child behavior. Participants were 25 male and 20 female adoptees, 12-18 years of age, having either a biological parent with substance abuse/dependency or antisocial personality or a biological parent with no such history. The study found that psychiatric disorders of biological parents were significantly related to children's antisocial/hostile behaviors and that biological parents' psychiatric disorders were associated with adoptive parents' behaviors. This genotype-environment association was largely mediated by adoptees' antisocial/hostile behaviors. Results also suggest that the adoptee's antisocial/hostile behavior and adoptive mother's parenting practices affect each other. (PsycINFO Database Record (c) 2010 APA, all rights reserved)