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https://www.readbyqxmd.com/read/28351121/probing-the-quantum-states-of-a-single-atom-transistor-at-microwave-frequencies
#1
Giuseppe Carlo Tettamanzi, Samuel James Hile, Matthew Gregory House, Martin Fuechsle, Sven Rogge, Michelle Y Simmons
The ability to apply gigahertz frequencies to control the quantum state of a single P atom is an essential requirement for the fast gate pulsing needed for qubit control in donor-based silicon quantum computation. Here, we demonstrate this with nanosecond accuracy in an all epitaxial single atom transistor by applying excitation signals at frequencies up to ≈13 GHz to heavily phosphorus-doped silicon leads. These measurements allow the differentiation between the excited states of the single atom and the density of states in the one-dimensional leads...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28351007/catalytic-role-of-iron-in-the-formation-of-silver-nanoparticles-in-photo-irradiated-ag-dissolved-organic-matter-solution
#2
Yongguang Yin, Dan Han, Chao Tai, Zhiqiang Tan, Xiaoxia Zhou, Sujuan Yu, Jingfu Liu, Guibin Jiang
Photo-reduction of Ag(+) to silver nanoparticle (AgNPs) by dissolved organic matter (DOM) is a possible source of naturally occurring AgNPs. However, how this photo-reduction process is influenced by ubiquitous metal ions is still not well understood. In addition, in previous studies, the formation of AgNPs in DOM solution was usually monitored by UV-Vis spectroscopy, and there is still lack of quantitative analysis for the formed AgNPs. In the present study, the role of Fe(2+)/Fe(3+) at environmental concentration level on this photochemical process was investigated, and the enhanced formation of AgNPs by Fe(2+)/Fe(3+) was probed and quantified by using UV-Vis spectroscopy, transmission electron microscopy, and liquid chromatography-inductively coupled plasma mass spectrometry...
March 25, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28350958/photo-controlled-sirna-delivery-and-biomarker-triggered-aiegen-emission-by-upconversion-nayf4-yb-3-tm-3-sio2-nanoparticles-for-inducing-and-monitoring-stem-cell-differentiation
#3
Jinming Li, Chris Wai Tung Leung, Dexter Siu Hong Wong, Jianbin Xu, Rui Li, Yueyue Zhao, Chris Yu Yee Yung, Engui Zhao, Benzhong Tang, Liming Bian
Controlling differentiation of stem cell and monitoring the cell differentiation has attracted much research interest since the discovery of stem cells. In this regard, a novel and personalized near-infrared (NIR) light-activated nanoplatform is obtained by encapsulating the photoactivated caged compound (DMNPE/siRNA) and combining a MMP13 cleavaged imaging peptide-tetrapheny-lethene (TPE) unit conjugated with the mesoporous silica coated upconversion nanoparticles (UCNPs) for the remote control of cell differentiation and simultaneously for real-time monitoring of differentiation...
March 28, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28350464/fluorescence-determination-of-omethoate-based-on-dual-strategy-for-improving-sensitivity
#4
Cuiping Zhang, Bixia Lin, Yujuan Cao, Manli Guo, Ying Yu
Omethoate is a frequently-used organophosphorus pesticide, the establishment of a sensitive, selective and simple method to determine omethoate is very important for food safety. In this paper, dual-strategy was applied to improve the detection sensitivity of omethoate. The first strategy, graphene quantum dots (GQDs) were doped with nitrogen to increase the fluorescence quantum yield to 30%. By coupling N-GQDs with omethoate aptamer, N-GQDs-aptamer probe was synthesized. The fluorescence of N-GQDs-aptamer probe was turned off by graphene oxide (GO), but recovered by omethoate...
March 28, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/28350441/chemical-probes-unravel-an-antimicrobial-defense-response-triggered-by-binding-of-the-human-opioid-dynorphin-to-a-bacterial-sensor-kinase
#5
Megan Holly Wright, Christian Fetzer, Stephan A Sieber
Host-microbe communication via small molecule signals is important for both symbiotic and pathogenic relationships, but is often poorly understood at the molecular level. Under conditions of host stress, levels of the human opioid peptide dynorphin are elevated, triggering virulence in the opportunistic pathogenic bacterium Pseudomonas aeruginosa via an unknown pathway. Here we apply a multilayered chemical biology strategy to unravel the mode of action of this putative interkingdom signal. We designed and applied dynorphin-inspired photoaffinity probes to reveal the protein targets of the peptide in live bacteria via chemical proteomics...
March 28, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28350437/bacteria-activated-theranostic-nanoprobes-against-methicillin-resistant-staphylococcus-aureus-infection
#6
Zhiwei Zhao, Rong Yan, Xuan Yi, Jingling Li, Jiaming Rao, Zhengqing Guo, Yanmei Yang, Weifeng Li, Yong-Qiang Li, Chunying Chen
Despite numerous advanced imaging and sterilization techniques available nowadays, the sensitive in vivo diagnosis and complete elimination of drug-resistant bacterial infections remain to be big challenge. Here we report a strategy to design activatable theranostic nanoprobes against methicillin-resistant Staphylococcus aureus (MRSA) infections. This probe is based on silica nanoparticles coated with vancomycin-modified polyelectrolyte-cypate complexes (SiO2-Cy-Van), which is activated by an interesting phenomenon of bacteria-responsive dissociation of the polyelectrolyte from silica nanoparticles...
March 28, 2017: ACS Nano
https://www.readbyqxmd.com/read/28347131/preclinical-in-vivo-cancer-straightway-to-patients
#7
Marion de Jong, Stephen Mather, Theodosia Maina
Detection of useful cellular targets has strongly stimulated personalized tumor-targeted imaging and therapy approaches, also involving synthesis and evaluation of nuclear imaging probes with potential for clinical applications. Reviews of preclinical and translational studies concerning such probes, including radiolabeled antibodies, nanobodies, affibodies, peptides, small molecule inhibitors, and nanoparticles, are presented in this issue. As most tracers described in these articles have been developed for the field of cancer imaging and radionuclide therapy, the current article on preclinical studies will focus on cancer research as well...
June 2017: Quarterly Journal of Nuclear Medicine and Molecular Imaging
https://www.readbyqxmd.com/read/28346841/rapid-and-reliable-genotyping-of-hla-b-57-01-in-four-chinese-populations-using-a-single-tube-duplex-real-time-polymerase-chain-reaction-assay
#8
Min Han, Xing Kang, Zhengbin Liu, Tingting Zhang, Yanwei Li, Chao Chen, Huijuan Wang
HLA-B*57:01 is strongly associated with severe adverse drug reaction induced by the anti-HIV drug abacavir (ABC) and antibiotic flucloxacillin. This study was dedicated to establishing a new method for HLA-B*57:01 genotyping and investigating the HLA-B*57:01 distribution pattern in four Chinese populations. A single-tube duplex real-time polymerase chain reaction (PCR) system was established by combining the amplification refractory mutation system and TaqMan probe. The reliability of this assay was validated by comparing the genotyping results with those by sequence-based typing...
March 27, 2017: AIDS Research and Human Retroviruses
https://www.readbyqxmd.com/read/28346816/child-adult-differences-in-using-dual-task-paradigms-to-measure-listening-effort
#9
Erin M Picou, Lauren M Charles, Todd A Ricketts
Purpose: The purpose of the project was to investigate the effects modifying the secondary task in a dual-task paradigm to measure objective listening effort. To be specific, the complexity and depth of processing were increased relative to a simple secondary task. Method: Three dual-task paradigms were developed for school-age children. The primary task was word recognition. The secondary task was a physical response to a visual probe (simple task), a physical response to a complex probe (increased complexity), or word categorization (increased depth of processing)...
March 27, 2017: American Journal of Audiology
https://www.readbyqxmd.com/read/28346778/direct-measurement-of-the-angular-pair-correlations-coefficients-in-molecular-liquids-using-nmr-benchmarking-force-fields-for-atomistic-simulations
#10
Leah Marie Heist, Chi-Duen Poon, Edward Thaddeus Samulski, Demetri J Photinos
High field deuterium NMR spectroscopy is used to characterize a number of molecular liquids and their mixtures in order to probe the directional part of the intermolecular interactions through the orientational ordering induced in the isotropic liquid phase by the spectrometer magnetic field. The systems studied include benzene, chloroform, hexafluorobenzene and thiophene at various concentrations and in mixtures. Dilution with the magnetically isotropic tetramethylsilane provides quantification of ordering at "infinite magnetic dilution", i...
March 27, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28346765/the-medial-temporal-memory-system-in-down-syndrome-translating-animal-models-of-hippocampal-compromise
#11
Caron A C Clark, Fabian Fernandez, Stella Sakhon, Goffredina Spanò, Jamie O Edgin
Recent studies have highlighted the dentate gyrus as a region of increased vulnerability in mouse models of Down syndrome (DS). It is unclear to what extent these findings are reflected in the memory profile of people with the condition. We developed a series of novel tasks to probe distinct medial temporal functions in children and young adults with DS, including object, spatial, and serial order memory. Relative to mental age-matched controls (n = 45), individuals with DS (n = 28) were unimpaired on subtests involving short-term object or configural recall that was divorced from spatial or temporal contexts...
March 27, 2017: Hippocampus
https://www.readbyqxmd.com/read/28346764/mapping-the-interactions-of-selective-biochemical-probes-of-antibody-conformation-by-hydrogen-deuterium-exchange-mass-spectrometry
#12
Ulrike Leurs, Hermann Beck, Lea Bonnington, Ingo Lindner, Ewa Pol, Kasper Dyrberg Rand
Protein-based pharmaceuticals represent the fastest growing group of drugs in development in the pharmaceutical industry. One of the major challenges in the discovery, development and distribution of biopharmaceuticals is the assessment of changes in their higher-order structure due to chemical modifications. Here, we investigate the interactions of three different biochemical probes (Fabs) generated to detect conformational changes in a therapeutic IgG1 antibody (mAbX) by local hydrogen-deuterium exchange mass spectrometry (HDX-MS)...
March 27, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28346733/the-ontogeny-and-population-variability-of-human-hepatic-dihydronicotinamide-riboside-quinone-oxidoreductase-nqo2
#13
Zoe Riches, Yuejian Liu, Jacob M Berman, Gurinder Walia, Abby C Collier
Dihydronicotinamide riboside:quinone oxidoreductase (NQO2) is an enzyme that performs reduction reactions involved in antioxidant defense. We hypothesized that NQO2 hepatic drug clearance would develop in children over time, similar to NQO1. Using human liver cytosol (n = 117), the effects of age, sex, ethnicity, and weight on NQO2 expression and activity were probed. No significant correlations were observed. Biochemical activity of NQO2 was as high at birth as in adults (0.23 ± 0.04 nmol/min/mg protein, mean ± SEM, range 0-1...
March 27, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28346731/exploring-the-influence-of-mpa-capped-cdte-quantum-dots-on-the-structure-and-function-of-lysozyme-probing-by-spectroscopic-and-calorimetric-methods
#14
Lining Zhao, Tao Sun, Xun Zhang, Wei Song, Rutao Liu
The effect of 3-mercaptopropionic acid (MPA)-capped CdTe quantum dots (QDs) on lysozyme was systematically investigated by spectroscopic methods, enzyme activity assay, and calorimetry techniques. Results show that the MPA-capped CdTe QDs binded to lysozyme through van der Walls forces and hydrogen bondings, causing the decrement of α-helical content (∼7%) and increment of β-sheet content (∼11%) of lysozyme. The binding caused static quenching of the fluorescence, while the microenvironment of aromatic amino acid residues did not show any significant alteration...
March 27, 2017: Journal of Biochemical and Molecular Toxicology
https://www.readbyqxmd.com/read/28346703/tunable-glut-hexose-binding-and-transport-via-modulation-of-hexose-c-3-hydrogen-bonding-capabilities
#15
Venkata Pavan Kondapi, Olivier Mohamad Soueidan, Christopher I Cheeseman, F G West
The importance of the hydrogen bonding interactions in the GLUT-hexose binding process has been demonstrated by studying the binding of structurally modified D-fructose analogues to GLUTs, and in one case its transport into cells. The presence of a hydrogen bond donor at the C-3 position of 2,5-anhydro-D-mannitol derivatives is essential for effective binding to GLUT5 and transport into tumor cells. Surprisingly, installation of a group that can function only as a hydrogen bond acceptor at C-3 resulted in selective recognition by GLUT1 rather than GLUT5...
March 27, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28346283/nonvisualized-sentinel-lymph-nodes-on-lymphoscintigraphy-in-melanoma-predictive-factors-and-surgical-outcomes
#16
Darryl Schuitevoerder, Lisa Grinlington, Jeffrey Stevens, Robert Nance, Jeanine Fortino, John T Vetto
PURPOSE: Preoperative lymphoscintigraphy is the standard for the identification of sentinel lymph nodes (SLNs) in melanoma. The impact of negative scintigraphy [nonvisualization (NV) of the SLN] on surgical outcomes is inadequately reported in the literature. The objectives of this study were to determine the incidence, predictive factors, and surgical outcomes of NV in clinically node-negative melanoma patients. PATIENTS AND METHODS: A retrospective review of a prospective, Institutional Review Board approved, melanoma sentinel node database from January 2005 to August 2015 was performed...
March 24, 2017: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/28346217/the-possibility-of-multi-layer-nanofabrication-via-atomic-force-microscope-based-pulse-electrochemical-nanopatterning
#17
Uksu Kim, Noboru Morita, Deug Lee, Martin Jun, Jeong Woo Park
Pulse electrochemical nanopatterning (PECN), a non-contact scanning probe lithography (NC-SPL) process using ultrashort voltage pulses, is based primarily on an electrochemical machining (ECM) process using localized electrochemical oxidation between a sharp tool tip and the sample surface. In this study, nanoscale oxide patterns were formed on silicon Si (100) wafer surfaces via electrochemical surface nanopatterning, by supplying external pulsed currents through non-contact atomic force microscopy. Nanoscale oxide width and height were controlled by modulating the applied pulse duration...
March 27, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28346138/dilation-of-fusion-pores-by-crowding-of-snare-proteins
#18
Zhenyong Wu, Oscar D Bello, Sathish Thiyagarajan, Sarah Marie Auclair, Wensi Vennekate, Shyam S Krishnakumar, Ben O'Shaughnessy, Erdem Karatekin
Hormones and neurotransmitters are released through fluctuating exocytotic fusion pores that can flicker open and shut multiple times. Cargo release and vesicle recycling depend on the fate of the pore, which may reseal or dilate irreversibly. Pore nucleation requires zippering between vesicle-associated v- and target membrane t-SNAREs, but the mechanisms governing the subsequent pore dilation are not understood. Here, we probed dilation of single fusion pores using v-SNARE-reconstituted ~23 nm diameter discoidal nanolipoprotein particles (vNLPs) as fusion partners with cells ectopically expressing cognate, 'flipped' t-SNAREs...
March 27, 2017: ELife
https://www.readbyqxmd.com/read/28345920/tuning-the-continuum-of-structural-states-in-the-native-ensemble-of-a-regulatory-protein
#19
Abhishek Narayan, Athi N Naganathan
The mesoscale nature of proteins allows for an efficient coupling between environmental cues and conformational changes enabling their function as molecular transducers. Delineating the precise structural origins of such a connection and the expected spectroscopic response has however been challenging. In this work, we perform a combination of urea-temperature double perturbation experiments and theoretical modeling to probe the conformational landscape of Cnu, a natural thermosensor protein. We observe unique ensemble signatures that point to a continuum of conformational sub-states in the native ensemble and that respond intricately to perturbations upon monitoring secondary-, tertiary-structures, distances between an intrinsic FRET pair and hydrodynamic volumes...
March 27, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28345918/direct-s0%C3%A2-t-excitation-of-a-conjugated-polymer-repeat-unit-unusual-spin-forbidden-transitions-probed-by-time-resolved-electron-paramagnetic-resonance-spectroscopy
#20
Deborah L Meyer, Florian Lombeck, Sven Huettner, Michael Sommer, Till Biskup
A detailed understanding of the electronic structure of semiconducting polymers and their building blocks is essential to develop efficient materials for organic electronics. (Time-resolved) electron paramagnetic resonance (EPR) is particularly suited to address these questions, allowing to directly detect paramagnetic states and to reveal their spin-multiplicity, besides its clearly superior resolution compared to optical meth- ods. We present here evidence for a direct S0→T optical excitation of distinct triplet states in the repeat unit of a conjugated polymer used in organic photovoltaics...
March 27, 2017: Journal of Physical Chemistry Letters
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