Rasta resin-DMAP and its use as a recyclable catalyst for the addition of carbon dioxide to epoxides

Rasta resin-DMAP, a new heterogeneous polystyrene-based amine, has been synthesized and used as a catalyst in addition reactions of carbon dioxide to epoxides to afford cyclic carbonate products. This new material was found to be a more efficient catalyst than divinyl benzene cross-linked polystyrene- supported DMAP, and was readily recovered and reused without significant loss of catalytic activity. © Georg Thieme Verlag Stuttgart - New York.postprin

Multifunctional organic polymeric catalysts and reagents

published_or_final_versio

Reactions of nitroalkenes with nitroalkanes or sulfur ylides catalyzed by amine-thiourea bifunctional polymeric organocatalysts

Non-cross-linked and cross-linked bifunctional polystyrenes bearing both amine and thiourea groups have been synthesized and used as organocatalysts in reactions between nitroalkenes and nitroalkanes or sulfur ylides. Control experiments using monofunctional polymers with only either amine or thiourea groups attached indicated that both functional groups were essential for efficient catalysis of the reactions studied. The non-cross-linked polystyrene was soluble in typical organic solvents and was used as a homogeneous catalyst, while the cross-linked polystyrene was used as a heterogeneous catalyst. © Georg Thieme Verlag Stuttgart · New York.postprin

Serological Prevalence of Schistosoma japonicum in Mobile Populations in Previously Endemic but Now Non-Endemic Regions of China: A Systematic Review and Meta-Analysis.

Background: Schistosomiasis japonica has been resurging in certain areas of China where its transmission was previously well controlled or interrupted. Several factors may be contributing to this, including mobile populations, which if infected, may spread the disease. A wide range of estimates have been published for S. japonicum infections in mobile populations, and a synthesis of these data will elucidate the relative risk presented from these groups. Methods: A literature search for publications up to Oct 31, 2014 on S. japonicum infection in mobile populations in previously endemic but now non-endemic regions was conducted using four bibliographic databases: China National Knowledge Infrastructure, WanFang, VIP Chinese Journal Databases, and PubMed. A meta-analysis was conducted by pooling one arm binary data with MetaAnalyst Beta 3.13. The protocol is available on PROSPERO (No. CRD42013005967). Results: A total of 41 studies in Chinese met the inclusion criteria, covering seven provinces of China. The time of post-interruption surveillance ranged from the first year to the 31st year. After employing a random-effects model, from 1992 to 2013 the pooled seroprevalence ranged from 0.9% (95% CI: 0.5-1.6%) in 2003 to 2.3% (95% CI: 1.5-3.4) in 1995; from the first year after the disease had been interrupted to the 31st year, the pooled seroprevalence ranged from 0.6% (95% CI: 0.2-2.1%) in the 27th year to 4.0% (95%CI: 1.3-11.3%) in the second year. The pooled seroprevalence in mobile populations each year was significantly lower than among the residents of endemic regions, whilst four papers reported a lower level of infection in the mobile populations than in the local residents out of only 13 papers which included this data. Conclusions: The re-emergence of S. japonicum in areas which had previously interrupted transmission might be due to other factors, although risk from re-introduction from mobile populations could not be excluded

Spatial imaging of Zn and other elements in Huanglongbing-affected grapefruit by synchrotron-based micro X-ray fluorescence investigation

Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacterium. After 12 months, affected plants showed typical HLB symptoms and significantly reduced Zn concentrations in leaves. Micro-XRF imaging of Zn and other nutrients showed that preferential localization of Zn to phloem tissues was observed in the stems and leaves collected from healthy grapefruit plants, but was absent from HLB-affected samples. Quantitative analysis by using standard references revealed that Zn concentration in the phloem of veins in healthy leaves was more than 10 times higher than that in HLB-affected leaves. No significant variation was observed in the distribution patterns of other elements such as Ca in stems and leaves of grapefruit plants with or without graft-inoculation of infected lemon scions. These results suggest that reduced phloem transport of Zn is an important factor contributing to HLB-induced Zn deficiency in grapefruit. Our report provides the first in situ, cellular level visualization of elemental variations within the tissues of HLB-affected citrus. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology

Infrared nano-spectroscopy via molecular expansion force detection

Mid-infrared absorption spectroscopy in the “molecular fingerprint” region (λ = 2.5–15 μm) is widely used for in situ analysis of chemical and biological samples. Due to the diffraction limit, traditional far-field techniques such as Fourier-transform infrared spectroscopy cannot take sample spectra with nanometer spatial resolution. To conduct nanoscale infrared measurement, in photoexpansion nano-spectroscopy, an atomic force microscope cantilever is used as a light absorption detector, in the way that the cantilever is deflected proportionally by the localized sample heating and expansion induced by infrared pulses. Previous studies of this new opto-mechanical technique demonstrated its powerfulness and simplicity, but relied on using high-power laser pulses to produce detectable cantilever deflection signal and it was difficult to measure ultra-thin samples below ~100 nm. In addition, the spatial resolution, though improved, is limited by the thermal diffusion length inside samples. This dissertation presents a set of experiments which have substantially improved photoexpansion nano-spectroscopy in terms of sensitivity and spatial resolution, and have explored other aspects of this technique. For the first time, high-quality photoexpansion spectra have been obtained from molecular monolayers using low-power infrared pulses from a tunable quantum cascade laser. The orders of magnitude improvement in sensitivity is due to the two methods we implemented: mechanical enhancement by the cantilever resonance, and optical enhancement by the metalized cantilever tip. The spatial resolution is also improved and only determined by the locally enhanced field below the tip. After that, the dissertation shows the spectral background signal, which comes from infrared absorption by the substrate and tip, can be suppressed using a second laser. We have also investigated the nonlinearity of tip-sample interaction, and are able to detect sample photoexpansion force at heterodyne frequency. In the last part of this dissertation, we use our technique to image local optical energy distribution and ohmic heat dissipation of the metal nanoantennas.Electrical and Computer Engineerin

Management of pediatric radiation dose using Philips fluoroscopy systems DoseWise: perfect image, perfect sense

Although image quality (IQ) is the ultimate goal for accurate diagnosis and treatment, minimizing radiation dose is equally important. This is especially true when pediatric patients are examined, because their sensitivity to radiation-induced cancer is two to three times greater than that of adults. DoseWise is an ALARA-based philosophy within Philips Medical Systems that is active at every level of product design. It encompasses a set of techniques, programs and practices that ensures optimal IQ while protecting people in the X-ray environments. DoseWise methods include management of the X-ray beam, less radiation-on time and more dose information for the operator. Smart beam management provides automatic customization of the X-ray beam spectrum, shape, and pulse frequency. The Philips-patented grid-controlled fluoroscopy (GCF) provides grid switching of the X-ray beam in the X-ray tube instead of the traditional generator switching method. In the examination of pediatric patients, DoseWise technology has been scientifically documented to reduce radiation dose to <10% of the dose of traditional continuous fluoroscopy systems. The result is improved IQ at a significantly lower effective dose, which contributes to the safety of patients and staff