Stereocontrolled Synthesis Of Highly Functionalized Heterocycles

Polysubstituted heterocycles appear in various natural compounds that have potential biological activity. Consequently, synthetic routes towards such compounds have become a major interest for organic chemists taking into consideration the importance of the stereochemical control during the course of synthesis. This report presents a tandem C֊H insertion - L. Α. promoted acetal cleavage sequence for a stereocontrolled synthesis of 2,3,5-trisubstituted THF derivatives and 2,3,5,6-tetrasubstituted oxepane derivatives via the use of an intermediate bicyclic template. This initial step involves ketalization of substituted 1,3-propanediols with methyl pyruvate to yield the 1,3-dioxane ring. Hydrolysis to the acid acetal and acylation of diazomethane using the mixed anhydride procedure yielded the diazocarbonyl precursor for the insertion reaction. The decomposition of the diazocarbonyl compound was catalysed by Rh(_2)(OAc)(_4) to yield an acceptor metallocarbene which inserted regioselectively into the C-H bond α to the oxygen atom in the dioxane ring to form a five membered ring yielding the bicyclic ketone template in a moderate yield. Reduction of the ketone was stereoselective and led to one epimer. Direct treatment of the resultant alcohol or the protected derivative with Et(SiH/L.A. led to the formation of the 2,3,5- trisubstituted THF derivative indicating that the diastereoselectivity was a function of the bulkiness of the alcohol protecting group. Subsequent inversion of the 7-OH stereochemistry directed the acetal cleavage reaction towards the formation of the oxepane ring which proved the crucial role of the hydroxyl or the alkoxy group at C(7) as a controller of the regioselectivity of the acetal cleavage reaction

Movers and Shakers: Kinetic Energy Harvesting for the Internet of Things

Numerous energy harvesting wireless devices that will serve as building blocks for the Internet of Things (IoT) are currently under development. However, there is still only limited understanding of the properties of various energy sources and their impact on energy harvesting adaptive algorithms. Hence, we focus on characterizing the kinetic (motion) energy that can be harvested by a wireless node with an IoT form factor and on developing energy allocation algorithms for such nodes. In this paper, we describe methods for estimating harvested energy from acceleration traces. To characterize the energy availability associated with specific human activities (e.g., relaxing, walking, cycling), we analyze a motion dataset with over 40 participants. Based on acceleration measurements that we collected for over 200 hours, we study energy generation processes associated with day-long human routines. We also briefly summarize our experiments with moving objects. We develop energy allocation algorithms that take into account practical IoT node design considerations, and evaluate the algorithms using the collected measurements. Our observations provide insights into the design of motion energy harvesters, IoT nodes, and energy harvesting adaptive algorithms.Comment: 15 pages, 11 figure

Methods of high current magnetic field generator for transcranial magnetic stimulation application

This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ± 1200 A can be generated with inputs of +/-20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG1) and MOSFET circuits (HCMFG2) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed

Resistance decay in individuals after antibiotic exposure in primary care: A systematic review and meta-analysis

Abstract Background Antibiotic resistance is an urgent global problem, but reversibility is poorly understood. We examined the development and decay of bacterial resistance in community patients after antibiotic use. Methods This was a systematic review and meta-analysis. PubMed, EMBASE and CENTRAL (from inception to May 2017) were searched, with forward and backward citation searches of the identified studies. We contacted authors whose data were unclear, and of abstract-only reports, for further information. We considered controlled or times-series studies of patients in the community who were given antibiotics and where the subsequent prevalence of resistant bacteria was measured. Two authors extracted risk of bias and data. The meta-analysis used a fixed-effects model. Results Of 24,492 articles screened, five controlled and 20 time-series studies (total 16,353 children and 1461 adults) were eligible. Resistance in Streptococcus pneumoniae initially increased fourfold after penicillin-class antibiotic exposure [odds ratio (OR) 4.2, 95% confidence interval (CI) 3.5–5.4], but this fell after 1 month (OR 1.7, 95% CI 1.3–2.1). After cephalosporin-class antibiotics, resistance increased (OR 2.2, 95%CI 1.7-2.9); and fell to (OR 1.6, 95% CI 1.2-2.3) at 1 month. After macrolide-class antibiotics, resistance increased (OR 3.8, 95% CI 1.9–7.6) and persisted for 1 month (OR 5.2, 95% CI 2.6–10.3) and 3 months (OR 8.1, 95% CI 4.6–14.2, from controlled studies and OR 2.3, 95% CI 0.6–9.4, from time-series studies). Resistance in Haemophilus influenzae after penicillins was not significantly increased (OR 1.3, 95% CI 0.9–1.9) initially but was at 1 month (OR 3.4, 95% CI 1.5–7.6), falling after 3 months (OR 1.0, 95% CI 0.5–2.2). Data were sparse for cephalosporins and macrolides. Resistance in Enterobacter increased post-exposure (OR 3.2, 95% CI 0.9–10.8, from controlled studies and OR 7.1, 95% CI 4.2–12, from time-series studies], but was lower after 1 month (OR 1.8, 95% CI 0.9–3.6). Conclusions Resistance generally increased soon after antibiotic use. For some antibiotic classes and bacteria, it partially diminished after 1 and 3 months, but longer-term data are lacking and urgently needed. Trial registration PROSPERO CRD42015025499

Philosophical Perspectives on Engineering and Technology Literacy, I

The belief that engineering and technology are beneficial to all and can improve human lives has inspired the tireless endeavors of many creative individuals throughout history. Engineers and technologists have generally believed that their actions and designs need to be scientifically justified and logically dependable. In addition, due to the pragmatic nature of the field there is also an emphasis on systematic approaches and defining standard practices in engineering. Such a positivist approach is seen in all aspects of engineering and technological ventures. Consequently, such an approach exists in most engineering educators’ perspectives and belief structures regarding the contents of the curricular, student training, and the overall goal of engineering and technological education.https://lib.dr.iastate.edu/ece_books/1000/thumbnail.jp

A novel experience-based internet intervention for smoking cessation : feasibility randomised controlled trial

The iPEx programme presents independent research funded by the UK National Institute for Health Research (NIHR) under its Programme Grants for Applied Research funding scheme (RP-PG-0608-10147). The views expressed in this paper are those of the authors, representing iPEx, and not necessarily those of the NHS, the NIHR or the Department of Health.Peer reviewedPublisher PD

Everybody needs sphingolipids, right!:Mining for new drug targets in protozoan sphingolipid biosynthesis

Sphingolipids (SLs) are an integral part of all eukaryotic cellular membranes. In addition, they have indispensable functions as signalling molecules controlling a myriad of cellular events. Disruption of either the de novo synthesis or the degradation pathways has been shown to have detrimental effects. The earlier identification of selective inhibitors of fungal SL biosynthesis promised potent broad-spectrum anti-fungal agents, which later encouraged testing some of those agents against protozoan parasites. In this review we focus on the key enzymes of the SL de novo biosynthetic pathway in protozoan parasites of the Apicomplexa and Kinetoplastidae, outlining the divergence and interconnection between host and pathogen metabolism. The druggability of the SL biosynthesis is considered, alongside recent technology advances that will enable the dissection and analyses of this pathway in the parasitic protozoa. The future impact of these advances for the development of new therapeutics for both globally threatening and neglected infectious diseases is potentially profound.<br/

Text Simplification and Generation Y: An Eye Tracking Study

While important information is often communicated via text, people read only a small fraction of textual content. Ignoring text is particularly prevalent among Generation Y, who prefer image-based communication and exhibit impatient viewing behavior. One way to improve the effectiveness of text-based communication for younger users is to construct textual information in a way that it can be understood with short glances, a hallmark of Generation Y’s impatient viewing behavior. To test this assertion, we used a set of plain language standards (PLS) to simplify a text passage from an actual website. The results of our eye tracking study showed that PLS were successful in improving textual communication for Generation Y users. The simplified text passage was processed with shorter glances, facilitated a more effective visual search behavior, and improved task performance significantly