Metal‐Free Synthesis of Chlorinated β‐Amino Ketones via an Unexpected Reaction of Imines with Arylacetylenes in 1,1,1,3,3,3‐Hexafluoro‐2‐propanol

The metal‐free reaction of terminal arylacetylenes with α,α‐dichloroaldimines in 1,1,1,3,3,3‐hexafluoro‐2‐propanol as the sole solvent results in the rapid and selective formation of γ,γ‐dichloro‐β‐amino ketones. In this solvent the expected dichlorinated propargylamines and/or allylic amines are not formed. The dichloromethylene moiety of the aldimine acts as an activating group and is essential to accomplish this transformation. Electron‐rich acetylenes lead to the best results and work well with all imines (with or without α′‐H at the nitrogen substituent), while electron‐deficient acetylenes only reacted with N‐tert‐butylaldimines (no α′‐H). The mechanistic pathway showed 1,1,1,3,3,3‐hexafluoro‐2‐propanol to protonate the aldimine, which in the rate‐determining step will react with the arylacetylene to form a resonance‐stabilized allene cation, which is trapped by a HFIP molecule giving rise to an enol ether, which promptly hydrolyzes to furnish exclusively the β‐amino ketones. Using DFT techniques we found that the first C C bond forming step is the rate‐determining step and is associated with a barrier of about 21 kcal mol⁻¹.

     

Immunologic cross-reaction between HIV type 1 p17 and Mycoplasma hyorhinis variable lipoprotein

The last decade has seen a surge in the use of computerized health care data for pharmacoepidemiology. Of all European databases, the General Practice Research Database (GPRD) in the UK, has been the most widely used for pharmacoepidemiological research. Since 1994, this database has belonged to the UK Department of Health, and is maintained by the Office of National Statistics (ONS). Currently, around 1500 general practitioners with a population coverage in excess of 3 million, systematically provide their computerized medical data anonymously to ONS. Validation studies of the GPRD have documented the recording of medical data into general practitioners' computers to be near to complete. The GPRD collects truly population-based data, has a size that makes it possible to follow-up large cohorts of users of specific drugs, and includes both outpatient and inpatient clinical information. The access to original medical records is excellent. Desirable improvements to the GPRD would be additional computerized information on certain variables and linkage to other health care databases. Most published studies to date have been in the area of drug safety. The General Practice Research Database has proved that valuable data can be collected in a general practice setting. The full potential of this rich computerized database has yet to come. This experience should serve to encourage others to develop similar population-based data in other countries.     

Development of Agrometeorological Crop Model Inputs from Remotely Sensed Information

The goal of developing agrometeorological crop model inputs from remotely sensed information (AgRISTARS Early Warning/Crop Condition Assessment Project Subtask 5 within the U. S. Department of Agriculture (USDA)) provided a focus and a mission for crop spectral investigations that would have been lacking otherwise. Because the task had never been attempted before, much effort has gone into developing measurement and interpretation skill, convincing the Scientific community of the validity and information content of the spectral measurements, and providing new understanding of the crop scenes viewed as affected by bidirectional, atmospheric, and soil background variations. Nonetheless, experiments conducted demonstrate that spectral vegetation indices (VI) a) are an excellent measure of the amount of green photosynthetically active tissue present in plant stands at any time during the season, and b) can reliably estimate leaf area index (LAI) and intercepted photosynthetically active radiation (IPAR)-two of the inputs needed in agrometeorological models. Progress was also made on using VI to quantify the effects of yield-detracting stresses on crop canopy development. In a historical perspective, these are significant accomplishments in a short time span. Spectral observations of fields from aircraft and satellite make direct checks on LAI and IPAR predicted by the agrometeorological models feasible and help extend the models to large areas. However, newness of the spectral interpretations, plus continual revisions in agrometeorological models and lack of feedback capability in them, have prevented the benefits of spectral inputs to agrometeorological models from being fully realized.     

焦化储煤系统中滑模施工施工缝的处理

当今工业与民用建筑高速发展的今天,各种新的技术层出不穷,滑膜施工作为一项成熟的新技术,在施工过程中不可避免的会有混凝土施工缝,如何保证施工缝位置的混凝土质量,也是滑膜过程中的重中之重。     

Analyse von rotwildmilch

Ohne Zusammenfassung     

Zur Theorie der Asynchronmaschine mit Reihenschluß-Drehfelderregermaschine

Ohne Zusammenfassung     

Beyond the group mind: A quantitative review of the interindividual-intergroup discontinuity effect.

This quantitative review of 130 comparisons of interindividual and intergroup interactions in the context of mixed-motive situations reveals that intergroup interactions are generally more competitive than interindividual interactions. The authors identify 4 moderators of this interindividual-intergroup discontinuity effect, each based on the theoretical perspective that the discontinuity effect flows from greater fear and greed in intergroup relative to interindividual interactions. Results reveal that each moderator shares a unique association with the magnitude of the discontinuity effect. The discontinuity effect is larger when (a) participants interact with an opponent whose behavior is unconstrained by the experimenter or constrained by the experimenter to be cooperative rather than constrained by the experimenter to be reciprocal, (b) group members make a group decision rather than individual decisions, (c) unconstrained communication between participants is present rather than absent, and (d) conflict of interest is severe rather than mild. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimal time byzantine agreement for t <n/8 with linear-messages

Summary.  This paper presents a Byzantine Agreement protocol with n=8t+1, optimal number of rounds (namely min{ f+2, t+1} where f is number of actual faults), and messages of linear size (namely m≦n+O(log n), where m stands for message size). All previous protocols that stop in optimal time and tolerate t=O(n) faults require messages of size at least O(n ²). The new protocol uses a novel technique called Reconstructed Traversal which is based on the Reconstruction Principle and on the Coordinated Traversal protocol. Received: August 1992/Accepted: January 1995l     

Estimation of total above-ground phytomass production using remotely sensed data

Remote sensing potentially offers a quick and nondestructive method for monitoring plant canopy condition and development. In this study, multispectral reflectance and thermal emittance data were used in conjunction with micrometeorological data in a simple model to estimate above-ground total dry phytomass production of several spring wheat canopies. The fraction of absorbed photosynthetic radiation (PAR) by plants was estimated from measurements of visible and near-infrared canopy reflectance. Canopy radiation temperature was used as a crop stress indicator in the model. Estimated above-ground phytomass values based on this model were strongly correlated with the measured phytomass values for a wide range of climate and plant-canopy conditions.