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https://www.readbyqxmd.com/read/28641260/nested-conjugate-gradient-algorithm-with-nested-preconditioning-for-non-linear-image-restoration
#1
Deepak G Skariah, Muthuvel Arigovindan
We develop a novel optimization algorithm, which we call Nested Non-Linear Conjugate Gradient algorithm (NNCG), for image restoration based on quadratic data fitting and smooth non-quadratic regularization. The algorithm is constructed as a nesting of two conjugate gradient (CG) iterations. The outer iteration is constructed as a preconditioned non-linear CG algorithm; the preconditioning is performed by the inner CG iteration that is linear. The inner CG iteration, which performs preconditioning for outer CG iteration, itself is accelerated by an another FFT based non-iterative preconditioner...
June 19, 2017: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28641156/mild-c-sp-3-h-functionalization-of-dihydrosanguinarine-and-dihydrochelerythrine-for-development-of-highly-cytotoxic-derivatives
#2
Adriana Romo-Pérez, Luis Demetrio Miranda, Alma D Chávez-Blanco, Alfonso Dueñas-González, María Del Rayo Camacho-Corona, Alejandrina Acosta-Huerta, Abraham García
A series of C(6)-substituted dihydrobenzo[c]phenanthridines were synthesized by mild copper-catalyzed C(sp(3))-H functionalization of dihydrosanguinarine (2) and dihydrochelerythrine (3) with certain nucleophiles selected to enhance cytotoxicity against human breast, colorectal, and prostate cancer cell lines. We also investigated the cytotoxicity of our previously reported C(6)-functionalized N-methyl-5,6-dihydrobenzo[c]phenanthridines 1a-1e to perform structure-activity relationship (SAR) studies. Among the target compounds, five β-aminomalonates (1a, 1b, 2a, 2b, and 3b), one α-aminophosphonate (2c), and one nitroalkyl derivative (2h) exhibited half maximal inhibitory concentration (IC50) values in the range of 0...
June 13, 2017: European Journal of Medicinal Chemistry
https://www.readbyqxmd.com/read/28641150/polyamine-and-tyramine-involvement-in-nacl-induced-improvement-of-cd-resistance-in-the-halophyte-inula-chrithmoides-l
#3
Rim Ghabriche, Tahar Ghnaya, Mejda Mnasri, Hanen Zaier, Raoudha Baioui, Delphine Vromman, Chedly Abdelly, Stanley Lutts
The aim of the present work was to analyze the impact of salinity on the plant response to Cd toxicity in the Mediterranean halophyte species Inula crithmoides. For this purpose, cuttings were cultivated hydroponically during 21d in the presence of 0, 25 or 50μM CdCl2 combined or not with 0, 100, 200 and 400mM NaCl. The obtained data demonstrated that, in the absence of Cd, NaCl strongly increased plant growth (the maximal dry weight being observed at 100mM) and enhanced the Na(+)/K(+) ratio in the shoot. Cd alone strongly affected plant growth in this halophyte...
June 6, 2017: Journal of Plant Physiology
https://www.readbyqxmd.com/read/28640998/oximes-and-hydrazones-in-bioconjugation-mechanism-and-catalysis
#4
Dominik K Kölmel, Eric T Kool
The formation of oximes and hydrazones is employed in numerous scientific fields as a simple and versatile conjugation strategy. This imine-forming reaction is applied in fields as diverse as polymer chemistry, biomaterials and hydrogels, dynamic combinatorial chemistry, organic synthesis, and chemical biology. Here we outline chemical developments in this field, with special focus on the past ∼10 years of developments. Recent strategies for installing reactive carbonyl groups and α-nucleophiles into biomolecules are described...
June 22, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28640997/from-1d-polymers-to-2d-polymers-preparation-of-free-standing-single-monomer-thick-two-dimensional-conjugated-polymers-in-water
#5
Na Zhang, Taisheng Wang, Xing Wu, Chen Jiang, Taiming Zhang, Bangkun Jin, Hengxing Ji, Wei Bai, Ruke Bai
Recently, investigation on two-dimensional (2D) organic polymers has been made a great progress and conjugated 2D polymers already play a dynamic role in both academic and practical applications. However, a convenient, non-interfacial approach to obtain single-layer 2D polymers in solution, especially in aqueous media remains challenging. Herein, we present a facile, highly efficient and versatile "1D to 2D" strategy for preparation of free-standing single-monomer-thick conjugated 2D polymers in water without any aid...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28640996/a-polyoxometalate-based-radiosensitization-platform-for-treating-hypoxic-tumor-by-attenuating-radio-resistance-and-enhancing-radiation-response
#6
Yuan Yong, Chunfang Zhang, Zhanjun Gu, Jiangfeng Du, Zhao Guo, Xinghua Dong, Jiani Xie, Guangjin Zhang, Xiangfeng Liu, Yuliang Zhao
Radioresistance is one of the undesirable impediments in hypoxia tumor, which sharply diminishes therapeutic effectiveness of radiotherapy and eventually results in the failure of their treatments. An attractive strategy for attenuating radioresistance is developing an ideal radiosensitization system with admirable radiosensitization capacity to attenuate tumor hypoxia and reinforce radiotherapy response in hypoxia tumor. Therefore, we describe the development of Gd-containing polyoxometalates-conjugated chitosan (GdW10@CS nanosphere) as a radiosensitization system for simultanous extrinsic and intrinsic radiosensitization, by generating overabundance cytotoxic reactive oxygen species (ROS) using high energy X-ray stimulation and mediating the hypoxia-inducible factor-1a (HIF-1a) siRNA to down-regulate HIF-1α expression and suppress the broken double-stranded DNA self-healing...
June 22, 2017: ACS Nano
https://www.readbyqxmd.com/read/28640992/crystalline-organic-pigment-based-field-effect-transistors
#7
Haichang Zhang, Ruonan Deng, Jing Wang, Xiang Li, Yu-Ming Chen, Kewei Liu, Clinton J Taubert, Stephen Z D Cheng, Yu Zhu
Three conjugated pigment molecules with fused hydrogen bonds, 3,7-diphenylpyrrolo[2,3-f]indole-2,6(1H,5H)-dione (BDP), (E)-6,6'-dibromo-[3,3'-biindolinylidene]-2,2'-dione (IIDG), and 3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo-[3,4-c]pyrrole-1,4-dione (TDPP), were studied in this work. The insoluble pigment molecules were functionalized with tert-butoxylcarbonyl (t-Boc) groups to form soluble pigment precursors (BDP-Boc, IIDG-Boc, and TDPP-Boc) with latent hydrogen bonding. The single crystals of soluble pigment precursors were obtained...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28640940/regioselective-direct-c-alkenylation-of-indoles
#8
Marino Petrini
The direct introduction of alkenyl groups into the indole framework avoiding its preliminary functionalization can be carried out using different synthetic strategies. Transition metal complexes facilitate the C-H activation of indoles or alkenes allowing an efficient Csp2- Csp2 bond formation. The hydroindolation of alkynes catalyzed by the same metal complexes or various acidic promoters can also be pursued for the alkenylation process. Conjugate addition of electron-poor alkenes and direct condensation of carbonyl derivative with indoles are also of interest for this purpose...
June 22, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28640936/preparation-single-molecule-manipulation-and-energy-transfer-investigation-of-a-polyfluorene-graft-dna-polymer
#9
Mikael Madsen, Rasmus S Christensen, Abhichart Krissanaprasit, Mette R Bakke, Camilla F Riber, Karina S Nielsen, Alexander Zelikin, Kurt Vesterager Gothelf
Conjugated polymers have been intensively studied due to their unique optical and electronic properties combined with their physical flexibility and scalable bottom up synthesis. While the bulk qualities of conjugated polymers have been extensively utilized in research and industry, the ability to handle and manipulate conjugated polymers at the nanoscale lacks significantly behind. Here we extend the toolbox for controlled manipulation of conjugated polymers through the synthesis of a polyfluorene-DNA graft type polymer (poly(F-DNA))...
June 22, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28640934/substrate-specificity-and-safener-inducibility-of-the-plant-udp-glucose-dependent-family-1-glycosyltransferases-super-family
#10
Melissa Brazier-Hicks, Markus Gershater, David Dixon, Robert Edwards
Plants contain large numbers of family 1 UDP-glucose dependent glycosyltransferases (UGTs), including members that conjugate xenobiotics. Arabidopsis contains 107 UGT genes with 99 family members successfully expressed as glutathione transferase (GST)-fusion proteins in E.coli. A high-throughput catalytic screen was developed based on quantification of the fusion by measuring GST activity. UGT activity using UDP-glucose as donor was then determined using 11 synthetic acceptors bearing hydroxyl, amino and thiol groups that had been shown to undergo conjugation in plant extracts...
June 22, 2017: Plant Biotechnology Journal
https://www.readbyqxmd.com/read/28640637/designing-transmitter-ligands-that-mediate-energy-transfer-between-semiconductor-nanocrystals-and-molecules
#11
Zhiyuan Huang, Ming Lee Tang
Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nano-crystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic-inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross-sections across the visible and near infrared wavelengths...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28640629/divergent-coupling-of-%C3%AE-%C3%AE-unsaturated-%C3%AE-ketoesters-with-simple-olefins-vinylation-and-2-2-cycloaddition
#12
Le Wang, Jian Lv, Sujia Li, Sanzhong Luo
Catalytic direct conjugate addition and [2 + 2] cycloaddition reactions of β,γ-unsaturated α-ketoesters with simple olefins have been developed, affording vinylation products and functionalized cyclobutanes, respectively, in good yields with high regioselectivity.
June 22, 2017: Organic Letters
https://www.readbyqxmd.com/read/28640590/chlorin-e6-functionalized-theranostic-multistage-nanovectors-transported-by-stem-cells-for-effective-photodynamic-therapy
#13
Simo Näkki, Jonathan Martinez, Michael Evangelopoulos, Wujun Xu, Vesa-Pekka Lehto, Ennio Tasciotti
Approaches to achieve site-specific and targeted delivery that provide an effective solution to reduce negative, off target side-effects are urgently needed for cancer therapy. Here, we utilized a Trojan horse-like strategy to carry photosensitizer Chlorin e6 conjugated porous silicon multistage nanovectors with tumor homing mesenchymal stem cells for targeted photodynamic therapy and diagnosis. The inherent versatility of multistage nanovectors permitted the conjugation of photosensitizers to enable precise cell death induction (60%) upon photodynamic therapy, while simultaneously retaining the loading capacity to load various payloads, such as antitumor drugs and diagnostic nanoparticles...
June 22, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28640589/ru-bpy-32-incorporated-luminescent-polymer-dots-double-enhanced-electrochemiluminescence-for-detection-of-single-nucleotide-polymorphism
#14
Yaqiang Feng, Feng Sun, Ningning Wang, Jianping Lei, Huangxian Ju
Encapsulating a large amount of electrochemiluminescence (ECL) active molecules into one nanoparticle for single target recognition can greatly improve the sensitivity of ECL assay. This work used luminescent conjugated polymer as a carrier to synthesize Ru(bpy)32+ doped polymer dots (RuPdots). The RuPdots with an average size of 20 nm and encapsulation of about 1354 Ru(bpy)32+ showed greatly enhanced ECL emission. Using tripropylamine as a co-reactant, the resonance energy transfer from the excited polymer dots to the encapsulated Ru(bpy)32+ was demonstrated, which led to 15...
June 22, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28637253/synthesis-and-secretion-of-isoflavones-by-field-grown-soybean
#15
Akifumi Sugiyama, Yumi Yamazaki, Shoichiro Hamamoto, Hisabumi Takase, Kazufumi Yazaki
Isoflavones play important roles in rhizosphere plant-microbe interactions. Daidzein and genistein secreted by soybean roots induce the symbiotic interaction with rhizobia and may modulate rhizosphere interactions with microbes. Yet despite their important roles, little is known about the biosynthesis, secretion and fate of isoflavones in field-grown soybeans. Here, we analysed isoflavone contents and the expression of isoflavone biosynthesis genes in field-grown soybeans. In roots, isoflavone contents and composition did not change with crop growth, but the expressions of UGT4, an isoflavone-specific 7-O-glucosyltransferase, and of ICHG (Isoflavone conjugates hydrolysing beta-glucosidase) was decreased during the reproductive stages...
June 16, 2017: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28637225/characteristics-of-escherichia-coli-isolated-from-broiler-chickens-with-colibacillosis-in-commercial-farms-from-a-common-hatchery
#16
H Ozaki, Y Matsuoka, E Nakagawa, T Murase
To investigate the epidemiologic aspects of colibacillosis in broiler chickens, 83 Escherichia coli isolates obtained from the pericarditis and perihepatitis lesions in broiler chickens from 4 commercial farms, 5 isolates recovered from 5 samples of yolk sac contents that were pooled from 25 emaciated chicks, and 4 fecal isolates obtained from a hatchery that supplied chicks to the 4 commercial farms mentioned above were genetically and bacteriologically characterized. Using pulsed-field gel electrophoresis (PFGE), a total of 92 isolates were classified into 33 pulsotypes...
June 20, 2017: Poultry Science
https://www.readbyqxmd.com/read/28637205/evolution-and-comparative-genomics-of-paqu-like-conjugative-plasmids-in-vibrio-species
#17
Ruichao Li, Lianwei Ye, Marcus Ho Yin Wong, Zhiwei Zheng, Edward Wai Chi Chan, Sheng Chen
Objectives: To investigate a set of MDR conjugative plasmids found in Vibrio species and characterize the underlying evolution process. Methods: pAQU-type plasmids from Vibrio species were sequenced using both Illumina and PacBio platforms. Bioinformatics tools were utilized to analyse the typical MDR regions and core genes in the plasmids. Results: The nine pAQU-type plasmids ranged from ∼160 to 206 kb in size and were found to harbour as many as 111 core genes encoding conjugative, replication and maintenance functions...
June 20, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28636798/a-ccpe-based-xenon-biosensor-for-magnetic-resonance-imaging-of-claudin-expressing-cells
#18
Anna Piontek, Christopher Witte, Honor May Rose, Miriam Eichner, Jonas Protze, Gerd Krause, Jörg Piontek, Leif Schröder
The majority of malignant tumors originate from epithelial cells, and many of them are characterized by an overexpression of claudins (Cldns) and their mislocalization out of tight junctions. We utilized the C-terminal claudin-binding domain of Clostridium perfringens enterotoxin (cCPE), with its high affinity to specific members of the claudin family, as the targeting unit for a claudin-sensitive cancer biosensor. To overcome the poor sensitivity of conventional relaxivity-based magnetic resonance imaging (MRI) contrast agents, we utilized the superior sensitivity of xenon Hyper-CEST biosensors...
June 2017: Annals of the New York Academy of Sciences
https://www.readbyqxmd.com/read/28636787/a-co-drug-conjugate-of-naringenin-and-lipoic-acid-mediates-neuroprotection-in-a-rat-model-of-oxidative-stress
#19
Tarek M Saleh, Monique C Saleh, Barry J Connell, Yang-Heon Song
Using our in vitro and in vivo models of oxidative stress, the current study was designed to determine the neuroprotective potential of naringenin, alone or in combination with lipoic acid. In our mixed neuronal culture exposed to hypoxia and subsequent reoxygenation, naringenin was shown to provide significant neuroprotection against cell death at a concentration of 2.5 μM. Lipoic acid (LA) did not produce neuroprotection at any concentration tested (0.25 to 100 μM). In contrast, when naringenin was covalently combined with LA, producing a novel compound named "VANL-100", significant neuroprotection was observed at a concentration as low as 2 x 10(-2) μM (100-fold more potent)...
June 21, 2017: Clinical and Experimental Pharmacology & Physiology
https://www.readbyqxmd.com/read/28636776/facile-synthesis-and-chain-length-dependent-optical-and-structural-properties-of-diketopyrrolopyrrole-based-oligomers
#20
Satish Patil, Tushita Mukhopadhyay, Boregowda Puttaraju, Palas Roy, Jyotishman Dasgupta, Andreas Meyer
Here we report the synthesis, optical properties and solid-state packing of monodisperse oligomers of DPP up to five repeating units. Optical properties of DPP-oligomers in solution and solid state were investigated by a combination of steady-state, and transient spectroscopy. Transient absorption spectroscopy and time-correlated single photon counting (TCSPC) measurements show that the fluorescence lifetime decreases with increase in the oligomer size from monomer to trimer, thereby reaching saturation for pentameric DPP oligomer...
June 21, 2017: Chemistry: a European Journal
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