The enhancement of stereoselectivity of a Pd-catalyzed three-component cascade reaction using parallel synthesis and multivariate analysis

Automated parallel synthesis with multivariate analysis was employed in the optimization of a Pd-catalyzed three-component cascade reaction of 7-buta-2,3-dienyl-1,3-dimethyl-3,7-dihydropurine-2,6-dione with iodobenzene and morpholine (see Scheme 1). Initially a range of reaction factors were analyzed using experimental design to optimize for selectivity, conversion, and impurity levels. Solvents and bases were screened separately as the substantial number of discrete variables involved is unsuited to the fractional factorial design used. Instead, a solvent principal component analysis (PCA) model was used in selection of solvents for screening, so gaining maximum variation in solvent properties. Similarly, tertiary amines were chosen by pKa for screening as bases alongside inorganic salts. This investigation yielded two-fold results, not only in enhancement of the reaction selectivity, but since significantly different findings were obtained on changing the solvent, the importance of the sequence of experimentation is also emphasized.     

Smoking cessation may not improve quality of life in atherosclerotic patients.

The benefits of smoking cessation on patients' medical conditions are well documented. Cardiovascular patients who quit smoking significantly reduce their risk of a new event compared with those who continue smoking. Several studies have found that smoking is related to poor quality of life (QoL). In cardiovascular patients, however, less attention has been given to the effect of smoking cessation on patients' QoL. The present study examined the extent to which smoking cessation leads to changes in QoL in these patients within the first year of follow-up. Data were collected in the context of a randomized clinical trial. Smoking outpatients (N = 346) with atherosclerotic disease were included and received medical treatment. They were randomized to receive either nicotine replacement therapy (NRT) or NRT plus a behavioral intervention meant to promote smoking cessation. At baseline, sociodemographic and clinical characteristics were established. Generic and disease-specific QoL as well as smoking status were assessed at baseline and with three follow-up measurements. Multilevel modeling showed that generic and disease-specific QoL in atherosclerotic patients improved significantly within the first year of follow-up. No main differences were found between quitters and smokers in terms of improvement in QoL. In fact, some subgroups reported a poorer QoL after smoking cessation: More highly educated patients reported lower general QoL (p < .05), and patients suffering from coronary artery disease who had a low level of education (p < .01) and patients suffering from peripheral arterial disease who had low nicotine dependency (p < .01) reported lower disease-specific QoL. Atherosclerotic patients' QoL improved significantly but was not enhanced by smoking cessation activities.     

A parametric study of the hydro-support

A mathematical model for a new type of navigation lock-gate support, the hydro-support, is presented. The hydro-support is a hydrostatic bearing, elastically connected to the lock-gate by a rubber hinge and sliding on an elastic polymer track. The model incorporates the pertinent physical aspects of the hydro-support, including the elastic deformation of the track, the bearing and the rubber hinge and the mixed lubrication between the bearing and the track. A calculation using this model on a typical hydro-support shows the contribution of the load carried by contact on the total load and the resulting increase of the friction forces.     

Ethische Aspekte der medikament?sen Behandlung dementer Patienten

Definition of the problem: The development and use of drugs aimed at a positive influence on the cognitive decline in patients suffering from Alzheimer's disease raises a number of ethical issues. Arguments: Among other things, these issues are concerned with the significance of these drugs for the patient's subjective well-being and quality of life and with aspects of informed consent to the use of these drugs, particularly in connection with their use in scientific medical research. Conclusion: The value and significance of antidementia drugs depends not only on their effect on cognitive decline, but also on their wider significance for patients' quality of life and their primary carers. The subjective experience of those directly involved deserves more attention in research and practice. Zusammenfassung. Die Entwicklung und die Verwendung von Antidementiva, die die Verzögerung des kognitiven Abbaus bei Alzheimer Patienten zum Ziel haben, werfen eine Reihe ethischer Fragen auf. Diese beziehen sich, neben anderen, auf die Bedeutung dieser Medikamente für das subjektive Wohlbefinden und die Lebensqualität des Patienten und auf Aspekte der Zustimmung zur Verwendung dieser Mittel nach Information, insbesondere im Rahmen der medizinisch-wissenschaftlichen Forschung. Der Wert und die Bedeutung der Antidementiva hängt nicht nur vom Effekt auf den kognitiven Abbau ab, sondern auch im weitesten Sinne von der Auswirkung auf die Lebensqualität der Patienten und ihrer primären Versorger. Die subjektiven Erfahrungen der unmittelbar Betroffenen bedürfen daher mehr Aufmerksamkeit als bisher, sowohl in der Forschung als auch in der Praxis.     

适度集成有助于汽车功率驱动系统设计

汽车电子系统设计人员在选择MOSFET器件时以前只有两种选择:没有任何保护措施的“简单”PowerMOS或具有完全保护的器件,后者在环境条件超出规定范围时会自动关闭,然而带有额外逻辑和保护电路的完全保护器件成本较高。因此,有些供应商开发了一种介于两者之间的适度集成的新型器件,在单芯片中结合了TrenchMOS技术以及温度和电流传感元件。其优点是不需要昂贵的智能功率器件即可为系统提供保护并节约空间。     

Quantum Effects in Three-Dimensional H + D2 Reaction at High Energies

The H + D₂ reactive system was studied in the energy range 0.84 < E_tr < 2.70 eV employing the ordinary Quasi-Classical Trajectory Approach (QCTA), the Classical and the Quantum Reactive Infinite Order Sudden Approximations (CRIOSA and QRIOSA), and the Angle-Oriented Transition State Theory (AOTST). From a detailed analysis of the various integral cross-sections and opacity functions, it was concluded that pronounced quantum effects ( > 10%) are expected in the high-energy region (≤ 2 eV).     

The DTX-240D digital circuit multiplication system

This paper describes the DTX-240D digital circuit multiplication system (DCMS) offered by ECI Telecom. It will accept up to 240 × 64 kb/s trunks carrying either 64 kb/s voice, voice band analogue non-speech signals, or digital data for transmission over a 2·048 Mb/s digital link. Over 1000 are currently ‘on-line’ and carrying traffic. The system comprises a pair of terminals, one on each side of the interterminal digital link (bearer). It will normally operate in the network at a concentration ratio of 5:1, in which case 150 × 64 kb/s trunks, carrying voice, voice band data or digital data can be concentrated into one 2·048 Mb/s bearer. The users are able to increase the number of trunks up to 240 per 2·048 Mb/s bearer, when time zone differences cause a spread of busy-hour traffic carried on a single system. Each terminal will normally be located at an international switching centre (ISC) but may also be located at an earth-station. The system uses a DSI (digital speech interpolation) stage providing a 2·5:1 multiplication, followed by an additional 2:1 multiplication by means of ADPCM (adaptive differential pulse code modulation). In addition, the VBR (variable bit rate) technique is used to prevent clipping, due to overload congestion. The system can also be used with 1·544 Mb/s digital bit streams (trunk side or bearer).