112,220 research outputs found
Organocatalytic Asymmetric Methodologies towards the Synthesis of Atropisomeric N-Heterocycles
No full textA perspective on the literature dealing with the organocatalytic asymmetric preparation of axially chiral N-heterocycles is provided. A particular focus is devoted to rationalize the synthetic strategies employed in each case. Moreover, specific classes of organocatalysts are shown to stand out as privileged motives for the stereoselective preparation of such synthetically challenging molecular architectures. Finally, an overview of the main trends in the field is given. 1 Introduction 2 Five-Membered Rings 2.1 Arylation 2.2 Dynamic Kinetic Resolution 2.3 Ring Construction 2.4 Central-to-Axial Chirality Conversion and Chirality Transfer 2.5 Desymmetrization 3 Six-Membered Rings 3.1 Desymmetrization 3.2 (Dynamic) Kinetic Resolution 3.3 Ring Construction 3.4 Central-to-Axial Chirality Conversion 4 Conclusion
Rewriting Hockey\u27s Unwritten Rules: Moore v. Bertuzzi
No full textThe word “enforcer” or “hockey goon” does not appear in the 2007–2008 National Hockey League (NHL) rulebook. However, every player and coach knows the meaning of those words. Hockey has always had its share of enforcers or “goons” that have protected star players. Steve Moore, former Harvard captain, and his parents have sued NHL tough-man Todd Bertuzzi, the Vancouver Canucks, and the partnership that owned the Canucks for an on-ice incident that occurred between Moore and Bertuzzi on March 8, 2004. Dedicated hockey fans have followed the lawsuit, but with the “incident” now over four years old many have forgotten about the vicious nature of the hit Bertuzzi rendered on Moore. Much of the discussion circulating around the Moore lawsuit has been that of hockey’s unwritten rule dealing with enforcers and hockey’s code of retaliation. Steve Moore’s lawsuit challenges hockey’s unwritten rules dealing with fighting and retaliation. Moore’s civil lawsuit has been frowned upon by some players. The outcome of the lawsuit could set the boundaries for future play in the NHL. Consider a sport where physically fit athletes are moving on skates at more than 20 miles an hour, wielding large wooden or metal sticks, and all vying for a 1 inch frozen piece of vulcanized rubber that has the ability to travel at more than 100 miles per hour. In addition, all of this activity takes place on a rock hard sheet of ice, 200 by 85 feet, with boundaries made of boards and glass. Whoever controls the puck also controls his future. A player could gain worldwide notoriety, obtain a lucrative contract, and eventually be presented with Lord Stanley’s Cup. Simply put, a lot is at stake
Diabetes mellitus: an opportunity for therapy with stem cells?
No full textIn both Type 1 and 2 diabetes, insufficient numbers of insulin-producing p-cells are a major cause of defective control of blood glucose and its complications. Restoration of damaged beta-cells by endocrine pancreas regeneration would be an ideal therapeutic option. The possibility of generating insulin-secreting cells with adult pancreatic stem or progenitor cells has been investigated extensively. The conversion of differentiated cells such as hepatocytes into beta-cells is being attempted using molecular insights into the transcriptional make-up of beta-cells. Additionally, the enhanced proliferation of beta-cells in vivo or in vitro is being pursued as a strategy for regenerative medicine for diabetes. Advances have also been made in directing the differentiation of embryonic stem cells into beta-cells. Although progress is encouraging, major gaps in our understanding of developmental biology of the pancreas and adult beta-cell dynamics remain to be bridged before a therapeutic application is made possible
Determination of Benzalkonium Homologues and Didecyldimethylammonium in Powdered and Liquid Milk for Infants by Hydrophilic Interaction Liquid Chromatography-Mass Spectrometry
No full textIn this study, a hydrophilic interaction liquid chromatography–
mass spectrometry (HILIC-MS/MS) method for
the determination of benzalkonium (BAC) homologues and
didecyldimethylammonium (DDAC) was developed. A satisfactory
chromatographic separation of BAC homologues and
DDAC was achieved using, as mobile phase, acetonitrile–
aqueous 50 mM ammonium formate (pH 3.2) (93+7 v/v) at
0.3 mL min−1. The elution order of BAC homologues was
from benzyldimethylhexadecylammonium chloride (C16-
BAC) to benzyldimethyldecylammonium chloride (C10-
BAC), the exact opposite with respect to separation using
reversed liquid chromatography. The instrumental method
was successfully applied to powdered and liquid milk for
infants (about 50 samples). From powdered milk samples,
BAC and DDAC were extracted using 5 % formic acid in
methanol for 60 min at 60 °C in an ultrasonic bath; after
dilution with water and 5 % NH4OH solution, a purification
step using a weak cationic exchange column was performed.
Satisfactory limit of detections (LODs) were achieved, below
1.0 μg kg−1 and 0.05 μg L−1 for powdered and liquid milk for
infants, respectively. No sample was free of BAC homologues
and DDAC, and in one powdered milk sample, the contamination
level exceeded 500 μg kg−1, the maximum level recommended
by the Standing Committee on the Food Chain
and Animal Health for food and feed
author-bios-SRD-19-0063.R1 – Supplemental material for The Network Structure of Police Misconduct
No full textSupplemental material, author-bios-SRD-19-0063.R1 for The Network Structure of Police Misconduct by George Wood, Daria Roithmayr and Andrew V. Papachristos in Socius</p
Evaluation and improvement of extraction methods for the analysis of aflatoxins B1, B2, G1 and G2 from naturally contaminated maize
No full textThe extraction procedure for aflatoxin determination in maize is based on a methanol-water (8+2 v/v) or an acetone-water (85+15 v/v) mixture. Initially, the extraction efficiency of two solvents was evaluated for each aflatoxin. Significantly higher levels of aflatoxin B1 were obtained by acetone-water, on the contrary higher levels of aflatoxin G2 were achieved by methanol-water. Then, acetone-water mixtures in different proportions (7+3, 6+4 and 5+5 v/v) were tested to improve the extraction of aflatoxin G2. Applying these extraction mixtures, the values both of aflatoxin B1 and of other aflatoxins were generally higher compared to those obtained by acetone-water 85+15; moreover, acetone-water (6+4) and (7+3) showed the best extraction efficiency for all aflatoxins
The ingestion of saturated fatty acid triacylglycerols acutely affects insulin secretion and insulin sensitivity in human subjects
No full textTo assess the effects of acute dietary saturated fat intake on glucose-induced insulin secretion rate (ISR), measured by the C-peptide deconvolution method, and on insulin clearance and sensitivity, five obese and five normal-weight women (controls) were studied after either a 100 g oral butter load or a 100 ml water load. At 120 min after the oral load a hyperglycaemic clamp was performed over 180 min. A dramatic increase of ISR occurred after butter compared with the water challenge in the controls (1305.6 (SE 124.1) v. 616.1 (SE 52.5) pmol/min; P<0.01) and to a lesser degree in the obese subjects (1975.0 (SE 44.1) v. 1417.5 (se 56.0) pmol/min; P<0.05). Insulin sensitivity was impaired after butter (0.60 x 10(-2) (SE 0.11 x 10(-2)) v. 2.26 x 10(-2) (SE 0.32 x 10(-2)) ml/min per kg FFM per (pmol/l); P<0.01) in the controls but not in the obese group. Insulin clearance during the clamp was reduced after butter compared with after the water load only in the controls (0.89 (SE 0.22) v. 1.70 (SE 0.15) litres/min; P<0.01). The data are consistent with the hypothesis that acute excess lipid availability may lead to a compensatory elevation in glucose-induced insulin secretion as a result of the decline in insulin sensitivity and a reduced insulin clearance
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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