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Rh system

Niels Thieme, Bernhard Breit
The rhodium-catalyzed atom-economic asymmetric N-selective intermolecular addition of purine derivatives to terminal allenes is reported. Branched allylic purines were obtained in high yields, regioselectivity and outstanding enantioselectivity utilizing a Rh/Josiphos catalyst. Conversely, linear selective allylation of purines could be realized in good to excellent regio- and E/Z-selectivity with a Pd/dppf catalyst system. Furthermore, the new methodology was applied to a straightforward asymmetric synthesis of carbocyclic nucleoside abacavir...
January 12, 2017: Angewandte Chemie
Sonya Gowtage, Gareth A Williams, Ray Henderson, Paul Aylett, Duncan MacMorran, Si Palmer, Andy Robertson, Sandrine Lesellier, Stephen P Carter, Mark A Chambers
The oral vaccination of wild badgers (Meles meles) with live Bacillus Calmette-Guérin (BCG) is one of the tools being considered for the control of bovine tuberculosis (caused by Mycobacterium bovis) in the UK. The design of a product for oral vaccination requires that numerous, and often competing, conditions are met. These include the need for a highly palatable, but physically stable bait that will meet regulatory requirements, and one which is also compatible with the vaccine formulation; in this case live BCG...
January 9, 2017: Vaccine
Thorsten M Beck, Bernhard Breit
An unprecedented highly regio- and enantioselective rhodium-catalyzed addition of 1,3-diketones to terminal and 1,1-disubstituted allenes furnishing asymmetric tertiary and quaternary all-carbon centers is reported. By applying a Rh(I) /phosphoramidite/TFA catalytic system under mild conditions, the desired chiral branched α-allylated 1,3-diketones could be obtained in good to excellent yields, with perfect regioselectivity and in high enantioselectivity. The reaction shows a broad functional-group tolerance on both reaction partners highlighting its synthetic potential...
January 11, 2017: Angewandte Chemie
Suman Shrestha, Srinivasan Vedantham, Andrew Karellas
In digital breast tomosynthesis and digital mammography, the x-ray beam filter material and thickness vary between systems. Replacing K-edge filters with Al was investigated with the intent to reduce exposure duration and to simplify system design. Tungsten target x-ray spectra were simulated with K-edge filters (50��m Rh; 50��m Ag) and Al filters of varying thickness. Monte Carlo simulations were conducted to quantify the x-ray scatter from various filters alone, scatter-to-primary ratio (SPR) with compressed breasts, and to determine the radiation dose to the breast...
January 11, 2017: Physics in Medicine and Biology
Xiaohong Hu, Qi Zhu, Zhibin Gu, Nan Zhang, Na Liu, Mishma S Stanislaus, Dawei Li, Yingnan Yang
TiO2 photocatalyst film recently has been utilized as the potential candidate for the wastewater treatment, due to its high stability and low toxicity. In order to further increase the photocatalytic ability and stability, different molecular weight of polyethylene glycol (PEG) were used to modify TiO2 structure to synthesize porous thin film used in the developed Photocatalytic-Ultrasonic system in this work. The results showed that PEG2000 modified TiO2 calcinated under 450°C for 2h exhibited the highest photocatalytic activity, attributed to the smallest crystallite size and optimal particle size...
May 2017: Ultrasonics Sonochemistry
Qian Wang, Takashi Hisatomi, Yohichi Suzuki, Zhenhua Pan, Jeongsuk Seo, Masao Katayama, Tsutomu Minegishi, Hiroshi Nishiyama, Tsuyoshi Takata, Kazuhiko Seki, Akihiko Kudo, Taro Yamada, Kazunari Domen
Development of sunlight-driven water splitting systems with high efficiency, scalability, and cost-competitiveness is a central issue for mass production of solar hydrogen as a renewable and storable energy carrier. Photocatalyst sheets comprising a particulate hydrogen evolution photocatalyst (HEP) and an oxygen evolution photocatalyst (OEP) embedded in a conductive thin film can realize efficient and scalable solar hydrogen production using Z-scheme water splitting. However, the use of expensive precious metal thin films that also promote reverse reactions is a major obstacle to developing a cost-effective process at ambient pressure...
January 6, 2017: Journal of the American Chemical Society
S Shrestha, S Vedantham, A Karellas
PURPOSE: In digital breast tomosynthesis (DBT) systems capable of digital mammography (DM), Al filters are used during DBT and K-edge filters during DM. The potential for standardizing the x-ray filters with Al, instead of K-edge filters, was investigated with intent to reduce exposure duration and to promote a simpler system design. METHODS: Analytical computations of the half-value thickness (HVT) and the photon fluence per mAs (photons/mm2/mAs) for K-edge filters (50µm Rh; 50µm Ag) were compared with Al filters of varying thickness...
June 2016: Medical Physics
Yue-Houng Hu, David A Scaduto, Wei Zhao
PURPOSE: Contrast-enhanced (CE) breast imaging involves the injection contrast agents (i.e., iodine) to increase conspicuity of malignant lesions. CE imaging may be used in conjunction with digital mammography (DM) or digital breast tomosynthesis (DBT) and has shown promise in improving diagnostic specificity. Both CE-DM and CE-DBT techniques require optimization as clinical diagnostic tools. Physical factors including x-ray spectra, subtraction technique, and the signal from iodine contrast, must be considered to provide the greatest object detectability and image quality...
November 21, 2016: Medical Physics
A Belsito, K Magnussen, C Napoli
Red cell alloimmunization is a serious problem in chronically transfused patients. A number of high-throughput DNA assays have been developed to extend or replace traditional serologic antigen typing. DNA-based typing methods may be easily automated and multiplexed, and provide reliable information on a patient. Molecular genotyping promises to become cheaper, being not dependent on serologic immunoglobulin reagents. Patients with hemoglobinopathies could benefit from receiving extended genomic typing. This could limit post transfusional complications depending on subtle antigenic differences between donors and patients...
December 9, 2016: Transfusion and Apheresis Science
Jyotsna Bhardwaj, Anjali Anand, V K Pandita, Shantha Nagarajan
To elucidate the mechanism responsible for magnetic field induced seed invigoration in aged seeds an experiment was conducted on six year old garden pea seeds stored under controlled (20 °C and 40% RH) condition. Aged seeds were magnetoprimed by exposing to pulsed magnetic field (PMF) of 100 mT for 1 h in three pulsed modes. The 6 min on and off PMF showed significant improvement in germination (7.6%) and vigor (84.8%) over aged seeds. Superoxide and hydrogen peroxide production increased in germinating primed seeds by 27 and 52%, respectively, over aged seeds...
November 2016: Journal of Food Science and Technology
Nayer Seyfizadeh, Narges Seyfizadeh, Hajar Negahdar, Seyed Reza Hosseini, Hajighorban Nooreddini, Hadi Parsian
Osteoporosis is known as a degenerative disease of the skeletal system and its main complication is fracture, which influences quality of life in the elderly. There are 4 major blood groups in humans based on the presence of A and B antigens. According to the investigations, there are reported relations between blood types and some diseases. In this study, the association between the ABO blood group and the prevalence of osteoporosis and osteopenia in an elderly population was investigated. Medical records of 990 elderly people were investigated in a cross-sectional study and the association between their blood group and the incidence of osteoporosis and osteopenia was analyzed using SPSS version 17...
December 26, 2016: Journal of Clinical Densitometry
Silvan Roth, Thomas Greber, Jürg Osterwalder
On the path to functional graphene electronics, suitable templates for chemical vapor deposition (CVD) growth of high-mobility graphene are of great interest. Among various substrates, hexagonal boron nitride (h-BN) has established itself as one of the most promising candidates. The nanomesh, a h-BN monolayer grown on the Rh(111) surface where the lattice mismatch of h-BN and rhodium leads to a characteristic corrugation of h-BN, offers an interesting graphene/h-BN interface, different from flat graphene/h-BN systems hitherto studied...
December 27, 2016: ACS Nano
Ho Ting Luk, Cecilia Mondelli, Daniel Curulla Ferré, Joseph A Stewart, Javier Pérez-Ramírez
Higher alcohols are important compounds with widespread applications in the chemical, pharmaceutical and energy sectors. Currently, they are mainly produced by sugar fermentation (ethanol and isobutanol) or hydration of petroleum-derived alkenes (heavier alcohols), but their direct synthesis from syngas (CO + H2) would comprise a more environmentally-friendly, versatile and economical alternative. Research efforts in this reaction, initiated in the 1930s, have fluctuated along with the oil price and have considerably increased in the last decade due to the interest to exploit shale gas and renewable resources to obtain the gaseous feedstock...
December 23, 2016: Chemical Society Reviews
Christopher Benndorf, Hellmut Eckert, Oliver Janka
Twenty new rare-earth metal rich intermetallic aluminium compounds, RE10TAl3 (RE = Y, Ho, Tm, Lu; T = Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt), were synthesized by arc melting the elements. The compounds crystallize, in analogy to e.g. the respective Cd representatives, with a ternary ordered structure as anti-type to the hexagonal Co2Al5 type, with the space group P63/mmc. The three crystallographically independent rare-earth metal sites occupy the aluminium positions of the aristotype, while the transition metal and aluminium atoms are ordered on the two cobalt sites...
December 23, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Ben C Hill, Courtney A Hanna, Jill Adamski, Huy P Pham, Marisa B Marques, Lance A Williams
Non-specific antibodies or antibodies of undetermined significance (AUS) often pose problems for a blood bank technologist and physician. It is well known that antibodies can weaken and evanesce over time, thus eluding detection by routine blood bank techniques. Special enhancement techniques exist (eg, ficin treatment); however, they are often underutilized due to concerns over expense. Ficin is known to enhance reactivity caused by antibodies in the ABO, Rh, Kidd, Lewis, I, and P blood group systems, while destroying reactivity of antibodies in the Duffy, and MNS blood group systems...
December 22, 2016: Laboratory Medicine
Shuanglin Qu, Christopher J Cramer
Density functional theory calculations have been performed to provide mechanistic insight into a series of Cp*CoIII- and Cp*RhIII-catalyzed directed C-H bond functionalizations with diazo-compound substrates. Co-based catalysis proceeds through five steps: C-H bond activation; C-C coupling via a concerted 1,2-aryl transfer; proto-demetalation; nucleophilic addition, and solvent-assisted methanol elimination. C-H bond activation is predicted to be reversible, consistent with deuterium-scrambling experiments...
December 22, 2016: Journal of Organic Chemistry
Xue Li, Dhrubajyoti Gupta, Jisoo Lee, Geonhee Park, Chul-Un Ro
Recently, ambient sea spray aerosols (SSAs) have been reported to undergo reactions with dicarboxylic acids (DCAs). Several studies have examined the hygroscopic behavior and chemical reactivity of aerosols generated from NaCl-DCA mixture solutions, but the results have varied, especially for the NaCl-malonic acid (NaCl-MA) mixture system. In this work, in situ Raman microspectrometry (RMS) was used to simultaneously monitor the change in chemical composition, size, and phase as a function of the relative humidity, for individual aerosols generated from NaCl-MA solutions, during two hygroscopic measurement cycles, which were performed first through the dehydration process, followed by a humidification process, in each cycle...
January 3, 2017: Environmental Science & Technology
Elham Lashkari, Hao Wang, Linshu Liu, Jing Li, Kit Yam
This research investigated the technical feasibility of metal-organic frameworks (MOFs) as novel delivery systems for encapsulation and controlled release of volatile allyl isothiocyanate (AITC) molecules. We hypothesized that water vapor molecules could act as an external stimulus to trigger the release of AITC molecules encapsulated in MOFs. To test this hypothesis, three MOFs-HKUST-1, MOF-74(Zn), and RPM6-Zn-were selected based on their structural properties and AITC molecular characteristics. Results from adsorption-desorption and GC headspace analyses showed that these MOFs could encapsulate and retain AITC molecules within their pores under low (30-35%) relative humidity (RH) conditions...
April 15, 2017: Food Chemistry
Florry E van den Boogaard, Jorrit J Hofstra, Xanthe Brands, Marcel M Levi, Joris J T H Roelofs, Sebastiaan A J Zaat, Cornelis Van't Veer, Tom van der Poll, Marcus J Schultz
BACKGROUND: Critically ill patients are at a constant risk of direct (e.g., by pneumonia) or indirect lung injury (e.g., by sepsis). Excessive alveolar fibrin deposition is a prominent feature of lung injury, undermining pulmonary integrity and function. METHODS: We examined the effect of local administration of recombinant human tissue factor pathway inhibitor (rh-TFPI), a natural anticoagulant, in two well-established models of lung injury in rats. Rats received intratracheal instillation of Pseudomonas aeruginosa, causing direct lung injury, or they received an intravenous injection of Escherichia coli lipopolysaccharide (LPS), causing indirect lung injury...
December 15, 2016: Journal of Aerosol Medicine and Pulmonary Drug Delivery
Alireza Khataee, Roya Lotfi, Aliyeh Hasanzadeh
A sensitive and simple flow injection chemiluminescence (CL) system was constructed for the determination of meropenem, in which the CL intensity of the KMnO4-rhodamine B (Rh B) reaction was enhanced in the presence of CdS quantum dots (QDs). A CL resonance energy transfer (CRET) occurs between CdS QDs as a donor and Rh B as an energy acceptor. Based on the strong specific quenching effect of meropenem on the CL intensity, a novel chemosensor for meropenem sensing was developed. Under the optimized conditions, the quenched CL emission intensity was proportional to the concentration of meropenem in the range of 0...
December 14, 2016: Photochemical & Photobiological Sciences
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