Use of attenuated total reflection infrared spectroscopy for analysis of partitioning of solutes between thin films and solution

The paper examines attenuated total reflection (ATR) spectroscopy as a tool for quantifying the partitioning of small molecular species between a solution and a thin film, while the film is directly exposed to the solution for equilibration. For the case of a thin film having a thickness substantially smaller than the decay length of the evanescent wave, we developed suitable linear relationships that relate the measured absorption of the characteristic band to the concentration of the species under study in the film and in solution. In the application of ATR-Fourier transform infrared spectroscopy, the method is particularly suitable for films a few tens to hundreds of nanometers thick and for solutes that preferentially partition into the film. As an example, the partitioning isotherm of 1-pentanol between water and a thin polyamide film separated from a reverse osmosis membrane was determined experimentally, and the limitations of the method are discussed.     

Assessing the suitability of three Australian fly ashes as an aluminosilicate source for geopolymers in high temperature applications

Fly ash characteristics cannot be assumed to be constant between power stations as they are highly dependent on the coal source and burning conditions. It is critical to understand the characteristics of fly ash in order to produce geopolymers suitable for high temperature applications. We report on the characterisation of fly ash from three Australian power stations in terms of elemental composition, phase composition, particle size, density and morphology. Geopolymers were synthesised from each of the fly ashes using sodium silicate and sodium aluminate solutions to achieve a range of Si:Al compositional ratios. Mechanical properties of geopolymer binders are presented and the effect of the source fly ash characteristics on the hardened product is discussed, as well as implications for high temperature applications. It was found that the twenty eight day strength of geopolymers is largely dependent on the sub 20 μm size fraction of the fly ash. Strength loss after high temperature exposure was found to be dependent on the concentration of iron in the fly ash precursor and the Si:Al ratio of the geopolymer mixture.     

Playing pinball with atoms

We demonstrate the feasibility of controlling an atomic scale mechanical device by an external electrical signal. On a germanium substrate, a switching motion of pairs of atoms is induced by electrons that are directly injected into the atoms with a scanning tunneling microscope tip. By precisely controlling the tip current and distance we make two atom pairs behave like the flippers of an atomic-sized pinball machine. This atomic scale mechanical device exhibits six different configurations.     

Social context and perceived effects of drugs on sexual behavior among individuals who use both heroin and cocaine.

Researchers have identified the association between the use of cocaine and sexual behavior as an important risk factor for HIV infection and have attempted to elucidate the nature of this association. Several lines of research have suggested that facilitation of sexual behavior during intoxication with cocaine may be because of the direct pharmacological effects of the drug (e.g., increase in sexual desire), whereas others have pointed to the importance of factors related to the context of drug use (e.g., opportunities for sexual behavior, expectations about the effects of the drug, social norms). The present study explored the perceived effects of cocaine and heroin on sexual behavior, as well as the social context of drug use as a function of drug type (cocaine vs. heroin), among 46 inner-city drug users who reported a history of regular use of both crack cocaine and heroin. Results indicated that compared to heroin, cocaine had deleterious effects on participants' perceived sexual desire and performance. Despite such deleterious effects on sexual behavior, cocaine was more frequently used with an intimate partner than heroin. Furthermore, participants did not differ in the extent to which they used the two drugs in other social contexts (e.g., with friends, family, or neighbors). These preliminary results suggest that the relationship between cocaine and sexual behavior, especially among long-term cocaine users, may be facilitated by opportunities for sex that exist in the context of cocaine use, rather than by the pharmacological effects of the drug. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intergroup helping as status relations: Effects of status stability, identification, and type of help on receptivity to high-status group's help.

Integrating research on social identity processes and helping relations, the authors proposed that low-status group members who are high identifiers will be unwilling to receive help from the high-status group when status relations are perceived as unstable and help is dependency-oriented. The first experiment, a minimal group experiment, found negative reactions to help from a high-status outgroup when status relations were unstable. The 2nd and 3rd experiments, which used real groups of Israeli Arabs and Israeli Jews, replicated this finding and showed that high identifiers were less receptive to help from the high-status outgroup than low identifiers. The 4th experiment, a help-seeking experiment with real groups of competing high schools, found that the least amount of help was sought from a high-status group by high identifiers when status relations were perceived as unstable and help was dependency-oriented. Theoretical and applied implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lay persons' sensitivity to statistical information: The case of high perceived applicability.

Six experimental studies were conducted to test the notion that lay persons are insensitive to statistical information when they are in the presence of individuating information allowing judgment by representativeness. Ss were 174 Israeli undergraduates and 259 members of the Israel Defense Forces. Two experiments examined the effects of reliability information on the regressiveness of predictions and on judgmental confidence. Two additional experiments examined the effects on confidence of informational redundancy. The final 2 studies examined Ss' capacity to reason in accordance with the notion of statistical information when its situational applicability is made apparent. On the basis of this and previous evidence, it is concluded that statistical rules seem to be used in accordance with the same rules that govern the use of nonstatistical rules, such as the "representativeness" rule and other rules of various contents. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Satisfaction with social support during crisis: Intimacy and self-esteem as critical determinants.

Satisfaction with social support was studied longitudinally in 113 17–40 yr old Israeli women following the outcome of both normal and medically complicated pregnancies (delivery by cesarean section, delivery of an infant weighing under 2 kg, or spontaneous abortion before the 3rd trimester). Ss were interviewed concerning the size of their social networks, the number of friends and family members in their networks, perceived intimacy with spouse, and perceived intimacy with at least 1 friend and 1 family member. Included in the interviews were measures of self-esteem, intimacy, social network structure, and satisfaction with support. Findings show that greater intimacy with spouse and with friends was related to greater satisfaction with support received during the crisis period. Intimate ties contributed to satisfaction with support independent of self-esteem, social network parameters, and type of pregnancy outcome. Social network parameters and pregnancy outcome were not related to satisfaction with support. Among Ss low in self-esteem, greater intimacy with family was related to lower satisfaction with support if the Ss lacked intimate ties with spouse or a friend. Clinical and social psychological theories regarding reaction to aid are discussed. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrathecal fentanyl with small-dose dilute bupivacaine: better anesthesia without prolonging recovery

Recent concern regarding lidocaine neurotoxicity has prompted efforts to find alternatives to lidocaine spinal anesthesia. Small-dose dilute bupivacaine spinal anesthesia yields a comparably rapid recovery profile but may provide insufficient anesthesia. By exploiting the synergism between intrathecal opioids and local anesthetics, it may be possible to augment the spinal anesthesia without prolonging recovery. Fifty patients undergoing ambulatory surgical arthroscopy were randomized into two groups receiving spinal anesthesia with 3 ml 0.17% bupivacaine in 2.66% dextrose without (Group I) or with (Group II) the addition of 10 microg fentanyl. Median block levels reached T7 and T8, respectively (P = not significant [NS]). Mean times to two-segment regression, S2 regression, time out of bed, time to urination, and time to discharge were 53 vs 67 min (P < 0.01), 120 vs 146 min (P < 0.05), 146 vs 163 min (P = NS), 169 vs 177 min (P = NS), and 187 vs 195 min (P = NS) respectively. Motor blockade was similar between groups, but sensory blockade was significantly more intense in Group II (P < 0.01). Six of 25 blocks failed in Group I, whereas none failed in Group II. The addition of 10 microg fentanyl to spinal anesthesia with dilute small-dose bupivacaine intensifies and increases the duration of sensory blockade without increasing the intensity of motor blockade or prolonging recovery to micturition or street fitness. IMPLICATIONS: Concerns about the neurotoxicity of lidocaine have prompted efforts to find alternatives to lidocaine spinal anesthesia. We studied 50 patients undergoing ambulatory surgical arthroscopy and found that although small-dose bupivacaine alone is inadequate for this procedure, the addition of fentanyl makes it reliable.