Increasing the Reactivity of Amides towards Organometallic Reagents: An Overview

The nucleophilic addition of carbon nucleophiles to amides has traditionally been a difficult task, both due to reactivity and selectivity problems. When successful, these processes would represent straightforward routes towards carbonyl‐type or amine compounds, depending on the fate of the generated tetrahedral intermediate. The direct addition of nucleophiles to amides for the preparation of ketones has been studied and applied to the syntheses of several natural products. On the other hand, the addition of nucleophiles to amides to obtain substituted amines represented a major challenge, and only scattered applications on particular substrates have appeared. Initial improvements were based on the activation of amides by introduction of particular substituents, such as in N‐methoxy amides (Weinreb amides) or electron‐withdrawing groups able to increase the carbon nucleophilicity. Although these strategies facilitate the introduction of nucleophiles, chemoselectivity issues arise when additional electrophilic moieties (i.e., carbonyls) are present, thus decreasing the versatility of the methods. In recent years, important advancements towards fully chemoselective methods have been realized. The capture of tetrahedral intermediates with acids generates highly electrophilic iminium species able to undergo chemoselective additions of various nucleophiles, thus accessing substituted amines. Alternatively, the in situ generation of an iminium triflate ion allows highly chemoselective additions of nucleophiles, yielding amines, ketones or ketimines. Also thioamides can be used as precursors of ketones or α‐substituted amines. The success of the above methodologies is further showcased by the application in various syntheses of natural products or biologically active molecules.

     

So what's a fellow?

Focuses on the 2 classes of the American Psychological Association membership: a lower class of Associates and Members, and an elite, who are called Fellows. Survey responses about the existence and administration of Fellow status indicate (1) a tendency toward retention of the status of Fellow and (2) a belief that it is a handy method of recognizing those who have made outstanding contributions to the field. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measurement of two social competence aspects in middle childhood.

[Correction Notice: An erratum for this article was reported in Vol 34(1) of Developmental Psychology (see record 2009-22882-001). On page 825, Method section, 4th paragraph, line 2, the sentence incorrectly reads, "The county sample consisted of 423 children (M =8 years 5 months, SD =3 years 3 months), constituting 71% of a randomly selected sample of children born in 1986 and living in a county in the middle of Sweden." The correct standard deviation in age in the county sample is 3 months.] The psychometric properties of a rating measure for parents and teachers for social competence, conceptualized as social skills and behaviors, were studied. The rating measure was constructed from factor analyses on 4 samples of school-age children. Factor analyses identified 2 moderately correlated competence aspects, valid for both sexes and for children from varying socioeconomic backgrounds. The first factor, Prosocial Orientation, captured a style promoting positive social interactions; the second factor, Social Initiative, described initiative as opposed to withdrawal in social situations. Scales based on the 2 factors showed reliability in internal consistency and stability across 1 year, validity in interrater agreement concurrently and across 1 year, correspondence with observed peer behavior, and the capacity to discriminate between children of different peer status. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of The psychotherapy of the elderly self.

Reviews the book, The psychotherapy of the elderly self by Hyman L. Muslin (see record 1992-98107-000). The purpose of this book is to describe the extension of psychoanalytic therapy in the Kohut mode to the elderly. Specifically the author describes the changes the elderly must cope with, the impact these changes have on the elderly self, and the kind of psychotherapy that will best help them cope with these changes. This book has a rather narrow focus, and is likely to be of interest mostly to those engaged in the Kohutian version of psychoanalytic psychotherapy. It does not present much material that is likely to be of help to those engaged in the more general practice of psychology with aged individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strain‐induced deformation mechanisms of polylactide plasticized with acrylated poly(ethylene glycol) obtained by reactive extrusion

This work aimed at identifying the tensile deformation mechanisms of an original grade of plasticized polylactide (pPLA) obtained by reactive extrusion. This material had a glass transition temperature of 32.6 °C and consisted of a polylactide (PLA) matrix grafted with poly(acryl‐poly(ethylene glycol)) (poly(Acryl‐PEG)) inclusions. pPLA behaved like a rubber‐toughened amorphous polymer at 20 °C, and its tensile behavior evolved toward a rubbery semicrystalline polymer with increasing temperature. The drawing of pPLA involved orientation of amorphous and crystalline chains, crystallization, and destruction of crystals. It was found that crystal formation and crystal destruction were in competition below 50 °C, resulting in a constant or slightly decreasing crystallinity with strain. Increasing temperature enhanced crystal formation and limited crystal destruction, resulting in an increased crystallinity with the strain level. Drawing yielded a transformation of the initial spherical poly(Acryl‐PEG) inclusions into ellipsoids oriented in the tensile direction. This mechanism may engender the formation of nanovoids within the inclusions due to a decreased density, assumed to be responsible for the whitening of the specimen. © 2015 Society of Chemical Industry     

Wafer-Scale Fabrication of Hierarchically Porous Silicon and Silica by Active Nanoparticle-Assisted Chemical Etching and Pseudomorphic Thermal Oxidation (Small 22/2023)

Many biological materials exhibit a multiscale porosity with small, mostly nanoscale pores as well as large, macroscopic capillaries to simultaneously achieve optimized mass transport capabilities and lightweight structures with large inner surfaces. Realizing such a hierarchical porosity in artificial materials necessitates often sophisticated and expensive top-down processing that limits scalability. Here, an approach that combines self-organized porosity based on metal-assisted chemical etching (MACE) with photolithographically induced macroporosity for the synthesis of single-crystalline silicon with a bimodal pore-size distribution is presented, i.e., hexagonally arranged cylindrical macropores with 1 µm diameter separated by walls that are traversed by pores 60 nm across. The MACE process is mainly guided by a metal-catalyzed reduction–oxidation reaction, where silver nanoparticles (AgNPs) serve as the catalyst. In this process, the AgNPs act as self-propelled particles that are constantly removing silicon along their trajectories. High-resolution X-ray imaging and electron tomography reveal a resulting large open porosity and inner surface for potential applications in high-performance energy storage, harvesting and conversion or for on-chip sensorics and actuorics. Finally, the hierarchically porous silicon membranes can be transformed structure-conserving by thermal oxidation into hierarchically porous amorphous silica, a material that could be of particular interest for opto-fluidic and (bio-)photonic applications due to its multiscale artificial vascularization.     

Food selection associated with sense of coherence in adults

Background  

Favorable dietary habits promote health, whereas unfavorable habits link to various chronic diseases. An individual's "sense of coherence" (SOC) is reported to correlate with prevalence of some diseases to which dietary habits are linked. However, understanding what determines an individual's dietary preferences and how to change his/her behavior remains limited. The aim of the present study was to evaluate associations between dietary intake and SOC in adults.     

Effect of betaine supplementation on cycling sprint performance

Purpose

To examine the effect of betaine supplementation on cycling sprint performance.

Methods

Sixteen recreationally active subjects (7 females and 9 males) completed three sprint tests, each consisting of four 12 sec efforts against a resistance equal to 5.5% of body weight; efforts were separated by 2.5 min of cycling at zero resistance. Test one established baseline; test two and three were preceded by seven days of daily consumption of 591 ml of a carbohydrate-electrolyte beverage as a placebo or a carbohydrate-electrolyte beverage containing 0.42% betaine (approximately 2.5 grams of betaine a day); half the beverage was consumed in the morning and the other half in the afternoon. We used a double blind random order cross-over design; there was a 3 wk washout between trials two and three. Average and maximum peak and mean power were analyzed with one-way repeated measures ANOVA and, where indicated, a Student Newman-Keuls.

Results

Compared to baseline, betaine ingestion increased average peak power (6.4%; p < 0.001), maximum peak power (5.7%; p < 0.001), average mean power (5.4%; p = 0.004), and maximum mean power (4.4%; p = 0.004) for all subjects combined. Compared to placebo, betaine ingestion significantly increased average peak power (3.4%; p = 0.026), maximum peak power max (3.8%; p = 0.007), average mean power (3.3%; p = 0.034), and maximum mean power (3.5%; p = 0.011) for all subjects combined. There were no differences between the placebo and baseline trials.

Conclusions

One week of betaine ingestion improved cycling sprint power in recreationally active males and females.     

Effects of orally administered yeast‐derived beta‐glucans: A review

Yeast‐derived beta‐glucans (Y‐BG) are considered immunomodulatory compounds suggested to enhance the defense against infections and exert anticarcinogenic effects. Specific preparations have received Generally Recognized as Safe status and acceptance as novel food ingredients by European Food Safety Authority. In human trials, orally administered Y‐BG significantly reduced the incidence of upper respiratory tract infections in individuals susceptible to upper respiratory tract infections, whereas significant differences were not seen in healthy individuals. Increased salivary IgA in healthy individuals, increased IL‐10 levels in obese subjects, beneficial changes in immunological parameters in allergic patients, and activated monocytes in cancer patients have been reported following Y‐BG intake. The studies were conducted with different doses (7.5–1500 mg/day), using different preparations that vary in their primary structure, molecular weight, and solubility. In animal models, oral Y‐BG have reduced the incidence of bacterial infections and levels of stress‐induced cytokines and enhanced antineoplastic effects of cytotoxic agents. Protective effects toward drug intoxication and ischemia/reperfusion injury have also been reported. In conclusion, additional studies following good clinical practice principles are needed in which well‐defined Y‐BG preparations are used and immune markers and disease endpoints are assessed. Since optimal dosing may depend on preparation characteristics, dose‐response curves might be assessed to find the optimal dose for a specific preparation.     

Estimation of the daily global solar radiation; Nepal experience

This work focuses on estimation of global solar radiation and, in particular, it explores the effect of precipitation and temperature on solar radiation profile of Kathmandu (Nepal). An accurate knowledge of solar radiation distribution in each particular geographical location is crucial for the promotion of solar energy technology. The best way of knowing the amount of global solar radiation is to install quality instruments at many locations in the given region. This requires their day to day maintenance, recording and calibration, which is very costly in developing countries like Nepal. Thus, the alternative approach is to correlate meteorological measurements with appropriate models and investigate the key parameters. For the research activities the RadEst program has been used. It includes, for evaluating the daily global solar radiation values at a given latitudes, four models which estimate the atmospheric transmissivity by measurements of daily temperature range and precipitations. The model parameters are fitted in 2 years data by iterative procedures. The values obtained by these models are, then, compared with measured radiation data. The paper reports graphical and statistical evaluations suggesting that among the four models, the Modular DCBB is the best model for Kathmandu area. This result is useful for designing solar panels able to maximize the harvesting of solar energy and to reduce the chronic shortage of hydrocarbon fuel that Nepal imports in a significant amount each year.