Synthesis and Characterization of Mixed Methyl/Allyl Monolayers on Si(111)

The formation of mixed methyl/allyl monolayers has been accomplished through a two-step halogenation/alkylation reaction on Si(111) surfaces. The total coverage of alkylated Si, the surface recombination velocities, and the degree of surface oxidation as a function of time have been investigated using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, and microwave conductivity measurements. The total coverage of alkyl groups, the rate of oxidation, and the surface recombination velocities of Si(111) terminated by mixed monolayers were found to be close to those observed for CH_3−Si(111) surfaces. Hence, the mixed-monolayer surfaces retained the beneficial properties of CH_3−Si(111) surfaces while allowing for convenient secondary surface functionalization

In Situ Nanomechanical Measurements of Interfacial Strength in Membrane-Embedded Chemically Functionalized Si Microwires for Flexible Solar Cells

Arrays of vertically aligned Si microwires embedded in polydimethylsiloxane (PDMS) have emerged as a promising candidate for use in solar energy conversion devices. Such structures are lightweight and concurrently demonstrate competitive efficiency and mechanical flexibility. To ensure reliable functioning under bending and flexing, strong interfacial adhesion between the nanowire and the matrix is needed. In situ uniaxial tensile tests of individual, chemically functionalized, Si microwires embedded in a compliant PDMS matrix reveal that chemical functionality on Si microwire surfaces is directly correlated with interfacial adhesion strength. Chemical functionalization can therefore serve as an effective methodology for accessing a wide range of interfacial adhesion between the rigid constituents and the soft polymer matrix; the adhesion can be quantified by measuring the mechanical strength of such systems

Vibrational Sum Frequency Spectroscopic Investigation of the Azimuthal Anisotropy and Rotational Dynamics of Methyl-Terminated Silicon(111) Surfaces

Polarization-selected vibrational sum frequency generation spectroscopy (SFG) has been used to investigate the molecular orientation of methyl groups on CH_(3)-terminated Si(111) surfaces. The symmetric and asymmetric C–H stretch modes of the surface-bound methyl group were observed by SFG. Both methyl stretches showed a pronounced azimuthal anisotropy of the 3-fold symmetry in registry with the signal from the Si(111) substrate, indicating that the propeller-like rotation of the methyl groups was hindered at room temperature. The difference in the SFG line widths for the CH_3 asymmetric stretch that was observed for different polarization combinations (SPS and PPP for SFG, visible, and IR) indicated that the rotation proceeded on a 1–2 ps time scale, as compared to the 100 fs rotational dephasing of a free methyl rotor at room temperature

Impaired Competence for Pretense in Children with Autism: Exploring Potential Cognitive Predictors.

Lack of pretense in children with autism has been explained by a number of theoretical explanations, including impaired mentalising, impaired response inhibition, and weak central coherence. This study aimed to empirically test each of these theories. Children with autism (n=60) were significantly impaired relative to controls (n=65) when interpreting pretense, thereby supporting a competence deficit hypothesis. They also showed impaired mentalising and response inhibition, but superior local processing indicating weak central coherence. Regression analyses revealed that mentalising significantly and independently predicted pretense. The results are interpreted as supporting the impaired mentalising theory and evidence against competing theories invoking impaired response inhibition or a local processing bias. The results of this study have important implications for treatment and intervention

Gender as a Moderator of the Relationship Between Preparty Motives and Event-Level Consequences

Prepartying is often associated with increased alcohol consumption and negative alcohol-related consequences among college students. General drinking motives are often only weakly related to preparty alcohol use, and few studies have examined the associations between preparty-specific drinking motives and alcohol-related consequences that occur during or after a preparty event. The current study utilizes event-level data to address this gap in the literature by examining the relationship between four types of preparty motives (prepartying to relax or loosen up, to increase control over alcohol use, to meet a dating partner, and to address concerns that alcohol may not be available later) and alcohol consequences as a function of gender. Participants (N = 952) reported on their most recent preparty event in the past month. After controlling for general drinking motives, all four preparty motives predicted greater event-level consequences for both males and females. Further, prepartying to increase control over alcohol consumed was associated with greater consequences for males as compared to females. The findings are consistent with research suggesting that preparty specific motives may further our understanding of prepartying outcomes over and above the use of general drinking motive measures

ALTERED ARTERIAL DOPPLER FLOW PATTERN AND PERINATAL OUTCOME IN INTRAUTERINE GROWTH RESTRICTION

ABSTRACTObjectives: Intrauterine growth restriction (IUGR) is one of the common conditions that interfere with the growth of the fetus accounting for 10-15%of pregnant woman. Literature explores a wide range of incidence of perinatal complication including mortality among IUGR pregnancies. Limiteddata available on these complications confined to coastal Karnataka and its association with abnormal arterial Doppler flow pattern. To study theperinatal complications associated with IUGR pregnancies and its prevalence in comparison to healthy controls of comparable gestational age.Methods: This cohort study screened 53 IUGR fetuses by an antenatal scan at gestational age of 27 weeks or more. The diagnosis of IUGR was madeaccording to established criteria from SOGC clinical practice guidelines August 2013. The data also included 48 appropriate for gestational age fetuseswith healthy mothers with the comparable gestational week. Experienced cardiac sonographer and gynecologist performed fetal echocardiography(ECHO) using Vivid 7, GE health-care system ECHO machine with the convex transducer of frequency 1.7-2.4 MHz. The study was conducted at southIndian tertiary care center.Results: This study included 53 IUGR cases and 48 non-IUGR controls. The mean age was 27±4.37 and 26.88±3.14 years in IUGR and non-IUGRgroups, respectively. Fetal Doppler study variables showed a significant decrease in peak aortic velocity and velocity time integral which was notevident on other valves, though mitral antegrade flow during atrial contraction was found to be lower among IUGR group. In two-dimensional chamberquantification of IUGR group revealed significant increase in pulmonary artery dimension, right ventricular (RV) dimension and RV thickness than thecontrol group (p<0.05). The anthropometric parameters such as weight and length; abdomen circumference was significantly lower in IUGR group,whereas head circumference found to be more in IUGR group (p<0.001). The gestational weeks at delivery was significantly different among twogroups with IUGR group depicting the early delivery group. p<0.001(35.58±2.92 and 38.5±0.96 in IUGR and non-IUGR groups, respectively). IUGRgroup also had prolonged neonatal intensive care unit stay when compared to controls (p<0.001).Conclusions: IUGR carries profound course in altered Doppler indices and cardiac function which explore its prediction on mortality and adverseperinatal outcome. This study showed significant perinatal mortality accounting for 5.6% among IUGR cases when compared to normal. Althoughtissue Doppler indices show normal variants, IUGR possesses significant adverse perinatal outcome, however with lesser incidence compared tosevere form of IUGR subsets who show altered tissue annular velocities.Keywords: Intrauterine growth restriction, Echocardiography, Doppler, Perinatal