Chemical exchange saturation transfer (CEST) properties of albumin-binding and gold nanoparticle-bound Eu (III) chelates

Science.gov (United States)

Melendez, Milleo Dalmacio

CEST agents derived from paramagnetic complexes, commonly referred to as PARACEST agents represent a new class of MRI contrast agents that respond to biological information such as pH, temperature, redox, and metabolite levels. In this work, CEST properties of two novel PARACEST agents were investigated upon binding to human serum albumin (HSA) and conjugation to gold nanoparticles (Au NPs). CEST properties of [EuDOTA(O-Et-Tyr)4] -when bound to HSA was studied to address the effect of proteins on CEST. The interaction of this Eu3+ complex to HSA was investigated by performing fluorescent probe displacement studies and it was found to bind HSA at two different binding pockets, the normal warfarin and dansyl glycine binding sites. The lipophilic pendant arms and the negative charge of this complex contribute to the favorable protein binding. However, the CEST signal was reduced 2-fold upon binding to HSA. The exchangeable protons on HSA provide a large proton pool that can exchange with the bound H 2O, competing for the exchange between bulk and bound water. Au NPs coated with [EuDOTA(CAM)4]3+ were prepared using the Brust method and characterized by measuring the CEST properties. The water residence lifetime for the Au-Eu NP conjugates increased 2-fold compared to the free Eu3+ complex presumably, as a result of the formation of hindered structure between the particle and the Eu3+ complex. Sensitivity enhancement in CEST was achieved by slowing down water exchange and increasing the number of exchangeable groups on the agent using Au-Eu NP conjugates. The CEST properties of small molecule PARACEST agents were shown to vary depending on the platform used in assembling larger adducts.

Facile one-pot formulation of TRAIL-embedded paclitaxel-bound albumin nanoparticles for the treatment of pancreatic cancer.

Science.gov (United States)

Min, Sun Young; Byeon, Hyeong Jun; Lee, Changkyu; Seo, Jisoo; Lee, Eun Seong; Shin, Beom Soo; Choi, Han-Gon; Lee, Kang Choon; Youn, Yu Seok

2015-10-15

Nanoparticle albumin-bound (nab™) technology is an effective way of delivering hydrophobic chemotherapeutics. We developed a one-pot/one-step formulation of paclitaxel (PTX)-bound albumin nanoparticles with embedded tumor necrosis factor-related apoptosis-inducing ligand (TRAIL/PTX HSA-NP) for the treatment of pancreatic cancer. TRAIL/PTX HSA-NPs were fabricated using a high-pressure homogenizer at a TRAIL feeding ratio of 0.2%, 1.0%, and 2.0%. TRAIL/PTX HSA-NPs were spherical and became larger in size (170-230 nm) with increasing TRAIL amount (0.2-2.0%). The loading efficiencies of PTX were in the range of ∼86.4% and significantly low at 2.0% TRAIL (60.4%). Specifically, the inhibitory concentrations (IC50) of TRAIL (1.0 or 2.0%)/PTX HSA-NPs were >20-fold lower than that of plain PTX-HSA NP (0.032±0.06, 0.022±0.005, and 0.96±0.15 ng/ml, respectively) in pancreatic Mia Paca-2 cells. Considering TRAIL loading, bioactivity, and particle size, TRAIL(1.0%)/PTX HSA-NPs were determined as the optimal candidate for further studies. TRAIL(1.0%)/PTX HSA-NPs displayed substantially greater apoptotic activity than plain PTX HSA-NP in both FACS and TUNEL analysis. The loaded PTX and TRAIL were gradually released from the TRAIL(1.0%)/PTX HSA-NPs until ∼24 h, which is considered to be a sufficient time for delivery to the tumor tissue. TRAIL(1.0%)/PTX HSA-NP displayed markedly more antitumor efficacy than plain PTX HSA-NP in Mia Paca-2 cell-xenografted mice in terms of tumor volume (size) and weight (213.9 mm(3) and 0.18 g vs. 1126.8 mm(3) and 0.80 g, respectively). These improved in vitro and in vivo performances were due to the combined synergistic effects of PTX and TRAIL. We believe that this TRAIL/PTX HSA-NP would have potential as a novel apoptosis-based anticancer agent. Copyright © 2015 Elsevier B.V. All rights reserved.

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

Science.gov (United States)

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG

Influence of the Debye length on the interaction of a small molecule-modified Au nanoparticle with a surface-bound bioreceptor.

Science.gov (United States)

Bukar, Natalia; Zhao, Sandy Shuo; Charbonneau, David M; Pelletier, Joelle N; Masson, Jean-Francois

2014-05-18

We report that a shorter Debye length and, as a consequence, decreased colloidal stability are required for the molecular interaction of folic acid-modified Au nanoparticles (Au NPs) to occur on a surface-bound receptor, human dihydrofolate reductase (hDHFR). The interaction measured using surface plasmon resonance (SPR) sensing was optimal in a phosphate buffer at pH 6 and ionic strength exceeding 300 mM. Under these conditions, the aggregation constant of the Au NPs was approximately 10(4) M(-1) s(-1) and the Debye length was below 1 nm, on the same length scale as the size of the folate anion (approximately 0.8 nm). Longer Debye lengths led to poorer SPR responses, revealing a reduced affinity of the folic acid-modified Au NPs for hDHFR. While high colloidal stability of Au NPs is desired in most applications, these conditions may hinder molecular interactions due to Debye lengths exceeding the size of the ligand and thus preventing close interactions with the surface-bound molecular receptor.

Adsorbent catalytic nanoparticles and methods of using the same

Energy Technology Data Exchange (ETDEWEB)

Slowing, Igor Ivan; Kandel, Kapil

2017-01-31

The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

Glucan Particles for Macrophage Targeted Delivery of Nanoparticles

Directory of Open Access Journals (Sweden)

Ernesto R. Soto

2012-01-01

Full Text Available Glucan particles (GPs are hollow, porous 2–4 μm microspheres derived from the cell walls of Baker's yeast (Saccharomyces cerevisiae. The 1,3-β-glucan outer shell provides for receptor-mediated uptake by phagocytic cells expressing β-glucan receptors. GPs have been used for macrophage-targeted delivery of soluble payloads (DNA, siRNA, protein, and small molecules encapsulated inside the hollow GPs via core polyplex and layer-by-layer (LbL synthetic strategies. In this communication, we report the incorporation of nanoparticles as cores inside GPs (GP-NP or electrostatically bound to the surface of chemically derivatized GPs (NP-GP. GP nanoparticle formulations benefit from the drug encapsulation properties of NPs and the macrophage-targeting properties of GPs. GP nanoparticle formulations were synthesized using fluorescent anionic polystyrene nanoparticles allowing visualization and quantitation of NP binding and encapsulation. Mesoporous silica nanoparticles (MSNs containing the chemotherapeutic doxorubicin (Dox were bound to cationic GPs. Dox-MSN-GPs efficiently delivered Dox into GP phagocytic cells resulting in enhanced Dox-mediated growth arrest.

A silica nanoparticle-based sensor for selective fluorescent detection of homocysteine via interaction differences between thiols and particle-surface-bound polymers

International Nuclear Information System (INIS)

Yu Changmin; Zeng Fang; Luo Ming; Wu Shuizhu

2012-01-01

Biothiols play crucial roles in maintaining biological systems; among them, homocysteine (Hcy) has received increasing attention since elevated levels of Hcy have been implicated as an independent risk factor for cardiovascular disease. Hence, the selective detection of this specific biothiol, which is a disease-associated biomarker, is very important. In this paper, we demonstrate a new mesoporous silica nanoparticle-based sensor for selective detection of homocysteine from biothiols and other common amino acids. In this fluorescent sensing system, an anthracene nitroolefin compound was placed inside the mesopores of mesoporous silica nanoparticles (MSNs) and used as a probe for thiols. The hydrophilic polyethylene glycol (PEG 5000) molecules were covalently bound to the MSN surface and used as a selective barrier for Hcy detection via different interactions between biothiols and the PEG polymer chains. The sensor can discriminate Hcy from the two low-molecular mass biothiols (GSH and Cys) and other common amino acids in totally aqueous media as well as in serum, with a detection limit of 0.1 μM. This strategy may offer an approach for designing other MSN-based sensing systems by using polymers as diffusion regulators in sensing assays for other analytes. (paper)

Study of dithiol monolayer as the interface for controlled deposition of gold nanoparticles

International Nuclear Information System (INIS)

Cichomski, M.; Tomaszewska, E.; Kosla, K.; Kozlowski, W.; Kowalczyk, P.J.; Grobelny, J.

2011-01-01

Self-assembled monolayer of dithiol molecules, deposited on polycrystalline Au (111), prepared at room atmosphere, was studied using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). Dithiols were used as interface, which chemically bonds to the deposited gold nanoparticles through strong covalent bonds. The size and size distribution of the deposited nanoparticles were measured using dynamic light scattering (DLS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The AFM results showed that nanoparticles are immobilized and stable during scanning procedure and do not contaminate the AFM tip. The size of monodisperse nanoparticles obtained from the DLS measurements is slightly higher than that obtained from the AFM and SEM measurements. This is due to the fact that the DLS measures the hydrodynamic radius, dependent on the protective chemical layer on nanoparticles. - Research Highlights: → Dithiols molecules create chemically bounded layers on a Au (111) surface. → Gold nanoparticles can be chemically bounded to a self-assembled monolayer. → Nanoparticles are stable during AFM probe interactions.

Determination of nanoparticle surface coatings and nanoparticle purity using microscale thermogravimetric analysis.

Science.gov (United States)

Mansfield, Elisabeth; Tyner, Katherine M; Poling, Christopher M; Blacklock, Jenifer L

2014-02-04

The use of nanoparticles in some applications (i.e., nanomedical, nanofiltration, or nanoelectronic) requires small samples with well-known purities and composition. In addition, when nanoparticles are introduced into complex environments (e.g., biological fluids), the particles may become coated with matter, such as proteins or lipid layers. Many of today's analytical techniques are not able to address small-scale samples of nanoparticles to determine purity and the presence of surface coatings. Through the use of an elevated-temperature quartz crystal microbalance (QCM) method we call microscale thermogravimetric analysis, or μ-TGA, the nanoparticle purity, as well as the presence of any surface coatings of nanomaterials, can be measured. Microscale thermogravimetric analysis is used to determine the presence and amount of surface-bound ligand coverage on gold nanoparticles and confirm the presence of a poly(ethylene glycol) coating on SiO2 nanoparticles. Results are compared to traditional analytical techniques to demonstrate reproducibility and validity of μ-TGA for determining the presence of nanoparticle surface coatings. Carbon nanotube samples are also analyzed and compared to conventional TGA. The results demonstrate μ-TGA is a valid method for quantitative determination of the coatings on nanoparticles, and in some cases, can provide purity and compositional data of the nanoparticles themselves.

Differential plasma protein binding to metal oxide nanoparticles

International Nuclear Information System (INIS)

Deng, Zhou J; Mortimer, Gysell; Minchin, Rodney F; Schiller, Tara; Musumeci, Anthony; Martin, Darren

2009-01-01

Nanoparticles rapidly interact with the proteins present in biological fluids, such as blood. The proteins that are adsorbed onto the surface potentially dictate the biokinetics of the nanomaterials and their fate in vivo. Using nanoparticles with different sizes and surface characteristics, studies have reported the effects of physicochemical properties on the composition of adsorbed plasma proteins. However, to date, few studies have been conducted focusing on the nanoparticles that are commonly exposed to the general public, such as the metal oxides. Using previously established ultracentrifugation approaches, two-dimensional gel electrophoresis and mass spectrometry, the current study investigated the binding of human plasma proteins to commercially available titanium dioxide, silicon dioxide and zinc oxide nanoparticles. We found that, despite these particles having similar surface charges in buffer, they bound different plasma proteins. For TiO 2 , the shape of the nanoparticles was also an important determinant of protein binding. Agglomeration in water was observed for all of the nanoparticles and both TiO 2 and ZnO further agglomerated in biological media. This led to an increase in the amount and number of different proteins bound to these nanoparticles. Proteins with important biological functions were identified, including immunoglobulins, lipoproteins, acute-phase proteins and proteins involved in complement pathways and coagulation. These results provide important insights into which human plasma proteins bind to particular metal oxide nanoparticles. Because protein absorption to nanoparticles may determine their interaction with cells and tissues in vivo, understanding how and why plasma proteins are adsorbed to these particles may be important for understanding their biological responses.

Thick electrodes including nanoparticles having electroactive materials and methods of making same

Science.gov (United States)

Xiao, Jie; Lu, Dongping; Liu, Jun; Zhang, Jiguang; Graff, Gordon L.

2017-02-21

Electrodes having nanostructure and/or utilizing nanoparticles of active materials and having high mass loadings of the active materials can be made to be physically robust and free of cracks and pinholes. The electrodes include nanoparticles having electroactive material, which nanoparticles are aggregated with carbon into larger secondary particles. The secondary particles can be bound with a binder to form the electrode.

Synthesis and characterization of titania-based monodisperse fluorescent europium nanoparticles for biolabeling

International Nuclear Information System (INIS)

Tan Mingqian; Wang Guilan; Ye Zhiqiang; Yuan Jingli

2006-01-01

Inorganic-organic hybrid titania-based nanoparticles covalently bound to a fluorescent Eu 3+ chelate of 4,4'-bis(1'',1'',1'',2'',2'',3'',3''-heptafluoro-4'',6''-hexanedion-6''-yl) chlorosulfo-o-terphenyl (BHHCT-Eu 3+ ) were synthesized by a sol-gel technique. A conjugate of BHHCT with 3-[2-(2-aminoethylamino) ethylamino]propyl-trimethoxysilane (APTS) was used as a precursor for the nanoparticle preparation and monodisperse nanoparticles consisting of titania network and silica sub-network covalently bound to the Eu 3+ chelate were prepared by the copolymerization of APTS-BHHCT conjugate, titanium tetraisopropoxide (TTIP) and free APTS in EuCl 3 water-alcohol solution. The effects of reaction conditions on size and fluorescence lifetime of the nanoparticles were investigated. The characterizations by transmission electron microscopy and fluorometric methods indicate that the nanoparticles are near spherical and strongly fluorescent having a fluorescence quantum yield of 11.6% and a long fluorescence lifetime of ∼0.4 ms. The direct-introduced amino groups on the nanoparticle's surface by using free APTS in nanoparticle preparation facilitated the biolabeling process of the nanoparticles. The nanoparticle-labeled streptavidin (SA) was prepared and used in a sandwich-type time-resolved fluoroimmunoassay (TR-FIA) of human prostate-specific antigen (PSA) by using a 96-well microtiter plate as the solid phase carrier. The method gives a detection limit of 66 pg/ml for the PSA assay

Albumin nanoparticles targeted with Apo E enter the CNS by transcytosis and are delivered to neurones.

Science.gov (United States)

Zensi, Anja; Begley, David; Pontikis, Charles; Legros, Celine; Mihoreanu, Larisa; Wagner, Sylvia; Büchel, Claudia; von Briesen, Hagen; Kreuter, Jörg

2009-07-01

The blood-brain barrier (BBB) represents a considerable obstacle to brain entry of the majority of drugs and thus severely restricts the therapy of many serious CNS diseases including brain tumours, brain HIV, Alzheimer and other neurodegenerative diseases. The use of nanoparticles coated with polysorbate 80 or with attached apolipoprotein E has enabled the delivery of drugs across the BBB. However, the mechanism of this enhanced transport is still not fully understood. In this present study, human serum albumin nanoparticles, with covalently bound apolipoprotein E (Apo E) as a targetor as well as without apolipoprotein E, were manufactured and injected intravenously into SV 129 mice. The animals were sacrificed after 15 and 30 min, and their brains were examined by transmission electron microscopy. Only the nanoparticles with covalently bound apolipoprotein E were detected in brain capillary endothelial cells and neurones, whereas no uptake into the brain was detectable with nanoparticles without apolipoprotein E. We have also demonstrated uptake of the albumin/ApoE nanoparticles into mouse endothelial (b.End3) cells in vitro and their intracellular localisation. These findings indicate that nanoparticles with covalently bound apolipoprotein E are taken up into the cerebral endothelium by an endocytic mechanism followed by transcytosis into brain parenchyma.

Penicillin-Bound Polyacrylate Nanoparticles: Restoring the Activity of β-Lactam Antibiotics Against MRSA

OpenAIRE

Turos, Edward; Reddy, G. Suresh Kumar; Greenhalgh, Kerriann; Ramaraju, Praveen; Abeylath, Sampath C.; Jang, Seyoung; Dickey, Sonja; Lim, Daniel V.

2007-01-01

This report describes the preparation of antibacterially-active emulsified polyacrylate nanoparticles in which a penicillin antibiotic is covalently conjugated onto the polymeric framework. These nanoparticles were prepared in water by emulsion polymerization of an acrylated penicillin analogue pre-dissolved in a 7:3 (w:w) mixture of butyl acrylate and styrene in the presence of sodium dodecyl sulfate (surfactant) and potassium persulfate (radical initiator). Dynamic light scattering analysis...

Effect of fullerenol surface chemistry on nanoparticle binding-induced protein misfolding

Science.gov (United States)

Radic, Slaven; Nedumpully-Govindan, Praveen; Chen, Ran; Salonen, Emppu; Brown, Jared M.; Ke, Pu Chun; Ding, Feng

2014-06-01

Fullerene and its derivatives with different surface chemistry have great potential in biomedical applications. Accordingly, it is important to delineate the impact of these carbon-based nanoparticles on protein structure, dynamics, and subsequently function. Here, we focused on the effect of hydroxylation -- a common strategy for solubilizing and functionalizing fullerene -- on protein-nanoparticle interactions using a model protein, ubiquitin. We applied a set of complementary computational modeling methods, including docking and molecular dynamics simulations with both explicit and implicit solvent, to illustrate the impact of hydroxylated fullerenes on the structure and dynamics of ubiquitin. We found that all derivatives bound to the model protein. Specifically, the more hydrophilic nanoparticles with a higher number of hydroxyl groups bound to the surface of the protein via hydrogen bonds, which stabilized the protein without inducing large conformational changes in the protein structure. In contrast, fullerene derivatives with a smaller number of hydroxyl groups buried their hydrophobic surface inside the protein, thereby causing protein denaturation. Overall, our results revealed a distinct role of surface chemistry on nanoparticle-protein binding and binding-induced protein misfolding.Fullerene and its derivatives with different surface chemistry have great potential in biomedical applications. Accordingly, it is important to delineate the impact of these carbon-based nanoparticles on protein structure, dynamics, and subsequently function. Here, we focused on the effect of hydroxylation -- a common strategy for solubilizing and functionalizing fullerene -- on protein-nanoparticle interactions using a model protein, ubiquitin. We applied a set of complementary computational modeling methods, including docking and molecular dynamics simulations with both explicit and implicit solvent, to illustrate the impact of hydroxylated fullerenes on the structure and

Synthesis and characterization of carboxylic acid functionalized silicon nanoparticles

Science.gov (United States)

Shaner, Ted V.

environment of the silicon surface of the nanoparticles. Modeling of the silicon nanoparticles and theoretical XANES spectra were also accomplished through the use of the FEFF9 software package. Results validate the infrared spectra results of more oxygen bound to the surfaces of larger silicon nanoparticles and less oxygen bound to smaller silicon nanoparticles. The photoluminescence was shown to greatly increase in yield after photoassisted exciton mediated hydrosilation. This has led to an increase of the luminescence yield of over an order of magnitude.

Quantum dot nanoparticle conjugation, characterization, and applications in neuroscience

Science.gov (United States)

Pathak, Smita

Quantum dot are semiconducting nanoparticles that have been used for decades in a variety of applications such as solar cells, LEDs and medical imaging. Their use in the last area, however, has been extremely limited despite their potential as revolutionary new biological labeling tools. Quantum dots are much brighter and more stable than conventional fluorophores, making them optimal for high resolution imaging and long term studies. Prior work in this area involves synthesizing and chemically conjugating quantum dots to molecules of interest in-house. However this method is both time consuming and prone to human error. Additionally, non-specific binding and nanoparticle aggregation currently prevent researchers from utilizing this system to its fullest capacity. Another critical issue that has not been addressed is determining the number of ligands bound to nanoparticles, which is crucial for proper interpretation of results. In this work, methods to label fixed cells using two types of chemically modified quantum dots are studied. Reproducible non-specific artifact labeling is consistently demonstrated if antibody-quantum dot conditions are less than optimal. In order to explain this, antibodies bound to quantum dots were characterized and quantified. While other groups have qualitatively characterized antibody functionalized quantum dots using TEM, AFM, UV spectroscopy and gel electrophoresis, and in some cases have reported calculated estimates of the putative number of total antibodies bound to quantum dots, no quantitative experimental results had been reported prior to this work. The chemical functionalization and characterization of quantum dot nanocrystals achieved in this work elucidates binding mechanisms of ligands to nanoparticles and allows researchers to not only translate our tools to studies in their own areas of interest but also derive quantitative results from these studies. This research brings ease of use and increased reliability to

Detection of magnetic nanoparticles with magnetoencephalography

Energy Technology Data Exchange (ETDEWEB)

Jia Wenyan [Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Xu, Guizhi [Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Biomedical Engineering, Hebei University of Technology, Tianjin, 300130 (China); Sclabassi, Robert J. [Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Zhu Jiangang [Department of Electrical and Computer Engineering, Carnegie Melon University, Pittsburgh, PA 15213 (United States); Bagic, Anto [Department of Neurology, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Sun Mingui [Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA 15260 (United States)], E-mail: mrsun@neuronet.pitt.edu

2008-04-15

Superconducting quantum interference devices (SQUIDs) have been widely utilized in biomedical applications due to their extremely high sensitivity to magnetic signals. The present study explores the feasibility of a new type of nanotechnology-based imaging method using standard clinical magnetoencephalographic (MEG) systems equipped with SQUID sensors. Previous studies have shown that biological targets labeled with non-toxic, magnetized nanoparticles can be imaged by measuring the magnetic field generated by these particles. In this work, we demonstrate that (1) the magnetic signals from certain nanoparticles can be detected without magnetization using standard clinical MEG, (2) for some types of nanoparticles, only bound particles produce detectable signals, and (3) the magnetic field of particles several hours after magnetization is significantly stronger than that of un-magnetized particles. These findings hold promise in facilitating the potential application of magnetic nanoparticles to in vivo tumor imaging. The minimum amount of nanoparticles that produce detectable signals is predicted by theoretical modeling and computer simulation.

Analysis of SiO2 nanoparticles binding proteins in rat blood and brain homogenate

Directory of Open Access Journals (Sweden)

Shim KH

2014-12-01

Full Text Available Kyu Hwan Shim,1 John Hulme,1 Eun Ho Maeng,2 Meyoung-Kon Kim,3 Seong Soo A An1 1Department of Bionano Technology, Gachon Medical Research Institute, Gachon University, Sungnam-si, 2Department of Analysis, KTR, Kimpo, Gyeonggi-do, 3Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea Abstract: A multitude of nanoparticles, such as titanium oxide (TiO2, zinc oxide, aluminum oxide, gold oxide, silver oxide, iron oxide, and silica oxide, are found in many chemical, cosmetic, pharmaceutical, and electronic products. Recently, SiO2 nanoparticles were shown to have an inert toxicity profile and no association with an irreversible toxicological change in animal models. Hence, exposure to SiO2 nanoparticles is on the increase. SiO2 nanoparticles are routinely used in numerous materials, from strengthening filler for concrete and other construction composites, to nontoxic platforms for biomedical application, such as drug delivery and theragnostics. On the other hand, recent in vitro experiments indicated that SiO2 nanoparticles were cytotoxic. Therefore, we investigated these nanoparticles to identify potentially toxic pathways by analyzing the adsorbed protein corona on the surface of SiO2 nanoparticles in the blood and brain of the rat. Four types of SiO2 nanoparticles were chosen for investigation, and the protein corona of each type was analyzed using liquid chromatography-tandem mass spectrometry technology. In total, 115 and 48 plasma proteins from the rat were identified as being bound to negatively charged 20 nm and 100 nm SiO2 nanoparticles, respectively, and 50 and 36 proteins were found for 20 nm and 100 nm arginine-coated SiO2 nanoparticles, respectively. Higher numbers of proteins were adsorbed onto the 20 nm sized SiO2 nanoparticles than onto the 100 nm sized nanoparticles regardless of charge. When proteins were compared between the two charges, higher numbers of proteins were

Can Nano-Particle Melt below the Melting Temperature of Its Free Surface Partner?

International Nuclear Information System (INIS)

Sui Xiao-Hong; Qin Shao-Jing; Wang Zong-Guo; Kang Kai; Wang Chui-Lin

2015-01-01

The phonon thermal contribution to the melting temperature of nano-particles is inspected. The discrete summation of phonon states and its corresponding integration form as an approximation for a nano-particle or for a bulk system have been analyzed. The discrete phonon energy levels of pure size effect and the wave-vector shifts of boundary conditions are investigated in detail. Unlike in macroscopic thermodynamics, the integration volume of zero-mode of phonon for a nano-particle is not zero, and it plays an important role in pure size effect and boundary condition effect. We find that a nano-particle will have a rising melting temperature due to purely finite size effect; a lower melting temperature bound exists for a nano-particle in various environments, and the melting temperature of a nano-particle with free boundary condition reaches this lower bound. We suggest an easy procedure to estimation the melting temperature, in which the zero-mode contribution will be excluded, and only several bulk quantities will be used as input. We would like to emphasize that the quantum effect of discrete energy levels in nano-particles, which is not present in early thermodynamic studies on finite size corrections to melting temperature in small systems, should be included in future researches. (condensed matter: structural, mechanical, and thermal properties)

Magnetic nanoparticles in magnetic resonance imaging and diagnostics.

Science.gov (United States)

Rümenapp, Christine; Gleich, Bernhard; Haase, Axel

2012-05-01

Magnetic nanoparticles are useful as contrast agents for magnetic resonance imaging (MRI). Paramagnetic contrast agents have been used for a long time, but more recently superparamagnetic iron oxide nanoparticles (SPIOs) have been discovered to influence MRI contrast as well. In contrast to paramagnetic contrast agents, SPIOs can be functionalized and size-tailored in order to adapt to various kinds of soft tissues. Although both types of contrast agents have a inducible magnetization, their mechanisms of influence on spin-spin and spin-lattice relaxation of protons are different. A special emphasis on the basic magnetism of nanoparticles and their structures as well as on the principle of nuclear magnetic resonance is made. Examples of different contrast-enhanced magnetic resonance images are given. The potential use of magnetic nanoparticles as diagnostic tracers is explored. Additionally, SPIOs can be used in diagnostic magnetic resonance, since the spin relaxation time of water protons differs, whether magnetic nanoparticles are bound to a target or not.

Analytical detection and biological assay of antileukemic drug using gold nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Selvaraj, V. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: rajselva_77@yahoo.co.in; Alagar, M. [Department of Chemical Engineering, Alagappa College of Technology, Anna University, Chennai 600025 (India)]. E-mail: mkalagar@yahoo.com; Hamerton, I. [Chemistry Division, School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)

2006-11-12

Gold nanoparticles are reported and evaluated as probes for the detection of anticancer drug 6-mercaptopurine (6-MP). The nature of binding between 6-MP and the gold nanoparticles via complexation is investigated using ultraviolet-visible spectrum, cyclic voltammetry, transmission electron microscopy, fluorescence and Fourier transform infrared (FT-IR) spectroscopy. The bound antileukemic drug is fluorescent and the quenching property of gold nanoparticles could be exploited for biological investigations. The 6-MP-colloidal gold complex is observed to have appreciable antibacterial and antifungal activity against Micrococcus luteus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Aspergillus fumigatus, and Aspergillus niger. The experimental studies suggest that gold nanoparticles have the potential to be used as effective carriers for anticancer drugs.

Gold Nanoparticle Labels Amplify Ellipsometric Signals

Science.gov (United States)

Venkatasubbarao, Srivatsa

2008-01-01

The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

Two-dimensional gold nanoparticle arrays. A platform for molecular optoelectronics

Energy Technology Data Exchange (ETDEWEB)

Mangold, Markus Andreas

2011-11-15

In my research, I study the optoelectronic properties of two-dimensional, hexagonal gold nanoparticle arrays formed by self-assembly. When the nanoparticle arrays are embedded in a matrix of alkane thiols, the photoresponse is dominated by a bolometric conductance increase. At room temperature, I observe a strong enhancement of the bolometric photoconductance when the surface plasmon resonance of the nanoparticles is excited. At cryogenic temperatures, the bolometric conductance enhancement leads to a redistribution of the potential landscape which dominates the optoelectronic response of the nanoparticle arrays. When optically active oligo(phenylene vinylene) (OPV) molecules are covalently bound to the nanoparticles, an increased photoconductance due to the resonant excitation of the OPV is observed. The results suggest that the charge carriers, which are resonantly excited in the OPV molecules, directly contribute to the current flow through the nanoparticle arrays. Thus, the conductance of OPV in its excited state is measured in the presented experiments. (orig.)

Nanoparticle albumin-bound paclitaxel as neoadjuvant chemotherapy of breast cancer: a systematic review and meta-analysis.

Science.gov (United States)

Zong, Yu; Wu, Jiayi; Shen, Kunwei

2017-03-07

The value of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) in neoadjuvant systemic therapy for breast cancer remains uncertain. Both electronic databases and proceedings of oncologic meetings were included in systematic literature search. Pooled rates of pathological complete response (pCR), odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using fixed-effect or random-effect model to determine the effect of neoadjuvant nab-paclitaxel. Twenty-one studies with 2357 patients were included, 3 of which were randomized clinical trials. The aggregate pCR(ypT0/is ypN0) rate was 32% (95% CI 25-38%) in unselected breast cancer patients and variated in different subtypes. Within randomized clinical trials, the probability of achieving pCR was significantly higher in the nab-paclitaxel group than in the conventional taxanes group (OR = 1.383, 95%CI 1.141-1.676, p = 0.001). For non-hematological toxic effect, any grade and grade 3-4 peripheral sensory neuropathy occurred more frequently with nab-paclitaxel compared to paclitaxel (any grade, OR = 2.090, 95%CI 1.016-4.302, p = 0.045; grade3-4, OR = 3.766, 95%CI 2.324-6.100, p < 0.001). Hypersensitivity was more common with paclitaxel than nab-paclitaxel at any grade and grade 3-4. nab-paclitaxel is an effective cytotoxic drug in neoadjuvant treatment of breast cancer, especially for aggressive tumors in terms of pCR. Exchange of nab-paclitaxel for conventional taxanes could significantly improve pCR rate with reasonable toxicities.

Interaction of ZnS nanoparticles with flavins and glucose oxidase: A fluorimetric investigation

International Nuclear Information System (INIS)

Chatterjee, Anindita; Priyam, Amiya; Ghosh, Debasmita; Mondal, Somrita; Bhattacharya, Subhash C.; Saha, Abhijit

2012-01-01

Interactions of luminescence, water soluble ZnS nanoparticles (NPs) with flavins and glucose oxidase have been thoroughly investigated through optical spectroscopy. The photoluminescence of ZnS nanoparticles was quenched severely (∼60%) by riboflavin while other flavins such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) show quenching to different extents under analogous conditions. However, interestingly no effect in luminescence intensity of ZnS NPs was observed with protein bound flavins such as in glucose oxidase. Fluorescence lifetime measurement confirmed the quenching to be static in nature. Scavenging of photo-generated electron of ZnS nanoparticles by the flavin molecules may be attributed to the decrease in luminescence intensity. Quenching of ZnS nanoparticles with flavins follows the linear Stern–Volmer plot. The Stern–Volmer constants decreased in the following order: K S−V (Riboflavin)> K S−V (FAD)> K S−V (FMN). This interaction study could generate useful protocol for the fluorimetric determination of riboflavin (vitamin B 2 ) content and also riboflavin status in biological systems. - Highlights: ► Unique interaction specificity of ZnS nanoparticles with flavins has been explored. ► Unlike protein-bound flavin, fluorescence of free flavins was quenched by ZnS nanoparticles. ► FMN and FAD show quenching to different extents under analogous conditions. ► Fluorescence lifetime measurement confirmed the quenching to be static in nature. ► This study is useful for probing riboflavin in biological systems.

Silver nanoparticles delivery system based on natural rubber latex membranes

Energy Technology Data Exchange (ETDEWEB)

Guidelli, Eder Jose, E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo/FFCLRP-DF (Brazil); Kinoshita, Angela [Universidade do Sagrado Coracao (Brazil); Ramos, Ana Paula [Universidade de Sao Paulo/FFCLRP-DQ (Brazil); Baffa, Oswaldo [Universidade de Sao Paulo/FFCLRP-DF (Brazil)

2013-04-15

The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV-Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane ({approx}0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.Graphical AbstractThe AgNP attached to the cis-isoprene molecules remain in the NRL matrix and only the AgNP bound to the non-rubber molecules (NRL serum fraction) are released. The released AgNP are

Silver nanoparticles delivery system based on natural rubber latex membranes

International Nuclear Information System (INIS)

Guidelli, Éder José; Kinoshita, Angela; Ramos, Ana Paula; Baffa, Oswaldo

2013-01-01

The search for new materials for biomedical applications is extremely important. Here, we present results on the performance of a silver nanoparticles delivery system using natural rubber latex (NRL) as the polymeric matrix. Our aim was to obtain an optimized wound dressing by combining materials with potential healing action. The synthesis of silver nanoparticles and their characterization by UV–Vis spectroscopy, transmission electron microscopy, zeta potential, dynamic light scattering, and Fourier transform infrared spectroscopy (FTIR) are depicted. The NRL membranes are good matrix for silver nanoparticles and allow for their gradual release. The release of 30 nm silver nanoparticles by the NRL membranes depends on their mass percentage in NRL membranes. The total concentration of AgNP released by the NRL membranes was calculated. The AgNP attached to the cis-isoprene molecules in the NRL matrix remain attached to the membrane (∼0.1 % w/w). So, only the AgNP bound to the non-rubber molecules are released. FTIR spectra suggest that non-rubber molecules, like aminoacids and proteins, associated with the serum fraction of the NRL may be attached to the surfaces of the released nanoparticles, thereby increasing the release of such molecules. The released silver nanoparticles are sterically stabilized, more stable and well dispersed. Because the serum fraction of the NRL is responsible for the angiogenic properties of the matrix, the silver nanoparticles could increment the angiogenic properties of NRL. This biomaterial has desirable properties for the fabrication of a wound dressing with potential healing action, since it combines the angiogenic and antibacterial properties of the silver nanoparticles with the increased angiogenic properties of the NRL.Graphical AbstractThe AgNP attached to the cis-isoprene molecules remain in the NRL matrix and only the AgNP bound to the non-rubber molecules (NRL serum fraction) are released. The released AgNP are sterically

Green synthesis of gold and silver nanoparticles using Hibiscus rosa sinensis

Science.gov (United States)

Philip, Daizy

2010-03-01

Biological synthesis of gold and silver nanoparticles of various shapes using the leaf extract of Hibiscus rosa sinensis is reported. This is a simple, cost-effective, stable for long time and reproducible aqueous room temperature synthesis method to obtain a self-assembly of Au and Ag nanoparticles. The size and shape of Au nanoparticles are modulated by varying the ratio of metal salt and extract in the reaction medium. Variation of pH of the reaction medium gives silver nanoparticles of different shapes. The nanoparticles obtained are characterized by UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR spectroscopy. Crystalline nature of the nanoparticles in the fcc structure are confirmed by the peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0) and (3 1 1) planes, bright circular spots in the selected area electron diffraction (SAED) and clear lattice fringes in the high-resolution TEM image. From FTIR spectra it is found that the Au nanoparticles are bound to amine groups and the Ag nanoparticles to carboxylate ion groups.

Drug loaded magnetic nanoparticles for cancer therapy

International Nuclear Information System (INIS)

Jurgons, R; Seliger, C; Hilpert, A; Trahms, L; Odenbach, S; Alexiou, C

2006-01-01

Magnetic nanoparticles have been investigated for biomedical applications for more than 30 years. In medicine they are used for several approaches such as magnetic cell separation or magnetic resonance imaging (MRI). The development of biocompatible nanosized drug delivery systems for specific targeting of therapeutics is the focus of medical research, especially for the treatment of cancer and diseases of the vascular system. In an experimental cancer model, we performed targeted drug delivery and used magnetic iron oxide nanoparticles, bound to a chemotherapeutic agent, which were attracted to an experimental tumour in rabbits by an external magnetic field (magnetic drug targeting). Complete tumour remission could be achieved. An important advantage of these carriers is the possibility for detecting these nanoparticles after treatment with common imaging techniques (i.e. x-ray-tomography, magnetorelaxometry, magnetic resonance imaging), which can be correlated to histology

DNA binding and aggregation by carbon nanoparticles

International Nuclear Information System (INIS)

An, Hongjie; Liu, Qingdai; Ji, Qiaoli; Jin, Bo

2010-01-01

Significant environmental and health risks due to the increasing applications of engineered nanoparticles in medical and industrial activities have been concerned by many communities. The interactions between nanomaterials and genomes have been poorly studied so far. This study examined interactions of DNA with carbon nanoparticles (CNP) using atomic force microscopy (AFM). We experimentally assessed how CNP affect DNA molecule and bacterial growth of Escherichia coli. We found that CNP were bound to the DNA molecules during the DNA replication in vivo. The results revealed that the interaction of DNA with CNP resulted in DNA molecule binding and aggregation both in vivo and in vitro in a dose-dependent manner, and consequently inhabiting the E. coli growth. While this was a preliminary study, our results showed that this nanoparticle may have a significant impact on genomic activities.

Circuit lower bounds in bounded arithmetics

Czech Academy of Sciences Publication Activity Database

Pich, Ján

2015-01-01

Roč. 166, č. 1 (2015), s. 29-45 ISSN 0168-0072 R&D Projects: GA AV ČR IAA100190902 Keywords : bounded arithmetic * circuit lower bounds Subject RIV: BA - General Mathematics Impact factor: 0.582, year: 2015 http://www.sciencedirect.com/science/article/pii/S0168007214000888

Determination of Non-Transferrin Bound Iron, Transferrin Bound Iron, Drug Bound Iron and Total Iron in Serum in a Rats after IV Administration of Sodium Ferric Gluconate Complex by Simple Ultrafiltration Inductively Coupled Plasma Mass Spectrometric Detection

Directory of Open Access Journals (Sweden)

Murali K. Matta

2018-02-01

Full Text Available A rapid, sensitive and specific ultrafiltration inductively-coupled plasma mass spectrometry method was developed and validated for the quantification of non-transferrin bound iron (NTBI, transferrin bound iron (TBI, drug bound iron (DI and total iron (TI in the same rat serum sample after intravenous (IV administration of iron gluconate nanoparticles in sucrose solution (Ferrlecit®. Ultrafiltration with a 30 kDa molecular cut-off filter was used for sample cleanup. Different elution solvents were used to separate each form of iron from sample serum. Isolated fractions were subjected to inductively-coupled mass spectrometric analysis after microwave digestion in 4% nitric acid. The reproducibility of the method was evaluated by precision and accuracy. The calibration curve demonstrated linearity from 5–500 ng/mL with a regression (r2 of more than 0.998. This method was effectively implemented to quantify rat pharmacokinetic study samples after intravenous administration of Ferrlecit®. The method was successfully applied to a pharmacokinetic (PK study of Ferrlecit in rats. The colloidal iron followed first order kinetics with half-life of 2.2 h and reached background or pre-dose levels after 12 h post-dosing. The drug shown a clearance of 0.31 mL/min/kg and volume of distribution of 0.05 L/kg. 19.4 ± 2.4 mL/h/kg.

Polyelectrolyte-modified cowpea mosaic virus for the synthesis of gold nanoparticles.

Science.gov (United States)

Aljabali, Alaa A A; Evans, David J

2014-01-01

Polyelectrolyte surface-modified cowpea mosaic virus (CPMV) can be used for the templated synthesis of narrowly dispersed gold nanoparticles. Cationic polyelectrolyte, poly(allylamine) hydrochloride, is electrostatically bound to the external surface of the virus capsid. The polyelectrolyte-coated CPMV promotes adsorption of aqueous gold hydroxide anionic species, prepared from gold(III) chloride and potassium carbonate, that are easily reduced to form CPMV-templated gold nanoparticles. The process is simple and environmentally benign using only water as solvent at ambient temperature.

Interaction of ZnS nanoparticles with flavins and glucose oxidase: A fluorimetric investigation

Energy Technology Data Exchange (ETDEWEB)

Chatterjee, Anindita; Priyam, Amiya; Ghosh, Debasmita; Mondal, Somrita [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata 700098 (India); Bhattacharya, Subhash C. [Department of Chemistry, Jadavpur University, Kolkata 700032 (India); Saha, Abhijit, E-mail: abhijit@alpha.iuc.res.in [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata 700098 (India)

2012-03-15

Interactions of luminescence, water soluble ZnS nanoparticles (NPs) with flavins and glucose oxidase have been thoroughly investigated through optical spectroscopy. The photoluminescence of ZnS nanoparticles was quenched severely ({approx}60%) by riboflavin while other flavins such as flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) show quenching to different extents under analogous conditions. However, interestingly no effect in luminescence intensity of ZnS NPs was observed with protein bound flavins such as in glucose oxidase. Fluorescence lifetime measurement confirmed the quenching to be static in nature. Scavenging of photo-generated electron of ZnS nanoparticles by the flavin molecules may be attributed to the decrease in luminescence intensity. Quenching of ZnS nanoparticles with flavins follows the linear Stern-Volmer plot. The Stern-Volmer constants decreased in the following order: K{sub S-V} (Riboflavin)> K{sub S-V} (FAD)> K{sub S-V} (FMN). This interaction study could generate useful protocol for the fluorimetric determination of riboflavin (vitamin B{sub 2}) content and also riboflavin status in biological systems. - Highlights: Black-Right-Pointing-Pointer Unique interaction specificity of ZnS nanoparticles with flavins has been explored. Black-Right-Pointing-Pointer Unlike protein-bound flavin, fluorescence of free flavins was quenched by ZnS nanoparticles. Black-Right-Pointing-Pointer FMN and FAD show quenching to different extents under analogous conditions. Black-Right-Pointing-Pointer Fluorescence lifetime measurement confirmed the quenching to be static in nature. Black-Right-Pointing-Pointer This study is useful for probing riboflavin in biological systems.

Determination of the surface density of polyethylene glycol on gold nanoparticles by use of microscale thermogravimetric analysis.

Science.gov (United States)

Sebby, K B; Mansfield, E

2015-04-01

The widespread integration of nanoparticle technologies into biomedicine will depend on the ability to repeatedly create particles with well-defined properties and predictable behaviors. For this to happen, fast, reliable, inexpensive, and widely available techniques to characterize nanomaterials are needed. Characterization of the surface molecules is particularly important since the surface, including the surface molecule density, plays a dominant role in determining how nanoparticles interact with their surroundings. Here, 10 and 30 nm gold nanoparticle NIST Standard Reference Materials were functionalized with fluorescently labeled polyethylene glycol (PEG) with either thiolate or lipoic acid anchoring groups to evaluate analytical techniques for determining surface coverage. The coating of the nanoparticles was confirmed with dynamic light scattering, microscale thermogravimetric analysis (μ-TGA), and ultraviolet-visible (UV-vis) spectroscopy. A UV-vis method for determining gold nanoparticle concentrations that takes into account spectral broadening upon functionalization was developed. The amount of bound PEG was quantified with μ-TGA, a technique analogous to thermogravimetric analysis that uses quartz crystal microbalances, and fluorescence spectroscopy of displaced ligands. It is shown that μ-TGA is a convenient technique for the quantification of ligands bound to inorganic particles while sacrificing a minimal amount of sample, and the treatment of the functionalized nanoparticle dispersions with dithiothreitol may be insufficient to achieve complete displacement of the surface ligands for quantification by fluorescence measurements. The μ-TGA and fluorescence results were used to determine ligand footprint sizes-average areas occupied by each ligand on the particles' surface. The lipoic acid bound ligands had footprint sizes of 0.21 and 0.25 nm(2) on 10 and 30 nm particles, respectively while the thiolate ligands had footprint sizes of 0.085 and 0

Zinc-phosphate nanoparticles with reversibly attached TNF-α analogs: an interesting concept for potential use in active immunotherapy

International Nuclear Information System (INIS)

Hribar, Gorazd; Žnidaršič, Andrej; Bele, Marjan; Maver, Uroš; Caserman, Simon; Gaberšček, Miran; Gaberc-Porekar, Vladka

2011-01-01

The authors’ intention was to prepare nanometer-sized zinc-phosphate nanoparticles that would be capable of binding histidine-rich TNF-α analogs onto their surface via a coordinative bond. Zinc-phosphate nanoparticles with a size of around 60 nm were prepared by a wet precipitation method and characterized using SEM, EDX, XRD, and DLS. First, BSA was bound as a testing protein, afterward two TNF-α analogs with decreased activity were bound to the described nanoparticles. The efficiency of binding and the existence of coordinative bond were confirmed with SDS-PAGE analysis. During binding, particle storage, and release experiments, the prepared TNF-α analogs retained their biological activity—hence the epitopes necessary for formation of antibodies stayed intact. The particle size did not change within a period of 2 weeks. No significant agglomeration was observed, the particles could be quickly dispersed in ultrasound. The present nanoparticles and the general approach of coordinative binding are widely applicable for natural and engineered histidine-rich proteins. The nanoparticles bearing appropriate TNF-α analogs could also be potentially used for active immunotherapy to tackle the chronic inflammatory diseases associated with pathogenically elevated levels of TNF-α.

Differential proteomics analysis of the surface heterogeneity of dextran iron oxide nanoparticles and the implications for their in vivo clearance.

Science.gov (United States)

Simberg, Dmitri; Park, Ji-Ho; Karmali, Priya P; Zhang, Wan-Ming; Merkulov, Sergei; McCrae, Keith; Bhatia, Sangeeta N; Sailor, Michael; Ruoslahti, Erkki

2009-08-01

In order to understand the role of plasma proteins in the rapid liver clearance of dextran-coated superparamagnetic iron oxide (SPIO) in vivo, we analyzed the full repertoire of SPIO-binding blood proteins using novel two-dimensional differential mass spectrometry approach. The identified proteins showed specificity for surface domains of the nanoparticles: mannan-binding lectins bound to the dextran coating, histidine-rich glycoprotein and kininogen bound to the iron oxide part, and the complement lectin and contact clotting factors were secondary binders. Nanoparticle clearance studies in knockout mice suggested that these proteins, as well as several previously identified opsonins, do not play a significant role in the SPIO clearance. However, both the dextran coat and the iron oxide core remained accessible to specific probes after incubation of SPIO in plasma, suggesting that the nanoparticle surface could be available for recognition by macrophages, regardless of protein coating. These data provide guidance to rational design of bioinert, long-circulating nanoparticles.

Perceptron Mistake Bounds

OpenAIRE

Mohri, Mehryar; Rostamizadeh, Afshin

2013-01-01

We present a brief survey of existing mistake bounds and introduce novel bounds for the Perceptron or the kernel Perceptron algorithm. Our novel bounds generalize beyond standard margin-loss type bounds, allow for any convex and Lipschitz loss function, and admit a very simple proof.

Prediction of the effects of size and morphology on the structure of water around hematite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Spagnoli, D.; Gilbert, B.; Waychunas, G.A.; Banfield, J. F.

2009-05-15

Compared with macroscopic surfaces, the structure of water around nanoparticles is difficult to probe directly. We used molecular dynamics simulations to investigate the effects of particle size and morphology on the time-averaged structure and the dynamics of water molecules around two sizes of hematite ({alpha}-Fe{sub 2}O{sub 3}) nanoparticles. Interrogation of the simulations via atomic density maps, radial distribution functions and bound water residence times provide insight into the relationships between particle size and morphology and the behavior of interfacial water. Both 1.6 and 2.7 nm particles are predicted to cause the formation of ordered water regions close to the nanoparticle surface, but the extent of localization and ordering, the connectivity between regions of bound water, and the rates of molecular exchange between inner and outer regions are all affected by particle size and morphology. These findings are anticipated to be relevant to understanding the rates of interfacial processes involving water exchange and the transport of aqueous ions to surface sites.

Study of Mesoporous Silica Nanoparticles' (MSNs) intracellular trafficking and their application as drug delivery vehicles

Science.gov (United States)

Yanes, Rolando Eduardo

Mesoporous silica nanoparticles (MSNs) are attractive drug delivery vehicle candidates due to their biocompatibility, stability, high surface area and efficient cellular uptake. In this dissertation, I discuss three aspects of MSNs' cellular behavior. First, MSNs are targeted to primary and metastatic cancer cell lines, then their exocytosis from cancer cells is studied, and finally they are used to recover intracellular proteins. Targeting of MSNs to primary cancer cells is achieved by conjugating transferrin on the surface of the mesoporous framework, which resulted in enhancement of nanoparticle uptake and drug delivery efficacy in cells that overexpress the transferrin receptor. Similarly, RGD peptides are used to target metastatic cancer cell lines that over-express integrin alphanubeta3. A circular RGD peptide is bound to the surface of MSNs and the endocytosis and cell killing efficacy of camptothecin loaded nanoparticles is significantly improved in cells that express the target receptor. Besides targeting, I studied the ultimate fate of phosphonate coated mesoporous silica nanoparticles inside cells. I discovered that the nanoparticles are exocytosed from cells through lysosomal exocytosis. The nanoparticles are exocytosed in intact form and the time that they remain inside the cells is affected by the surface properties of the nanoparticles and the type of cells. Cells that have a high rate of lysosomal exocytosis excrete the nanoparticles rapidly, which makes them more resistant to drug loaded nanoparticles because the amount of drug that is released inside the cell is limited. When the exocytosis of MSNs is inhibited, the cell killing efficacy of nanoparticles loaded with camptothecin is enhanced. The discovery that MSNs are exocytosed by cells led to a study to determine if proteins could be recovered from the exocytosed nanoparticles. The procedure to isolate exocytosed zinc-doped iron core MSNs and identify the proteins bound to them was developed

Recent Advances in the Application of Magnetic Nanoparticles as a Support for Homogeneous Catalysts

Science.gov (United States)

Govan, Joseph; Gun’ko, Yurii K.

2014-01-01

Magnetic nanoparticles are a highly valuable substrate for the attachment of homogeneous inorganic and organic containing catalysts. This review deals with the very recent main advances in the development of various nanocatalytic systems by the immobilisation of homogeneous catalysts onto magnetic nanoparticles. We discuss magnetic core shell nanostructures (e.g., silica or polymer coated magnetic nanoparticles) as substrates for catalyst immobilisation. Then we consider magnetic nanoparticles bound to inorganic catalytic mesoporous structures as well as metal organic frameworks. Binding of catalytically active small organic molecules and polymers are also reviewed. After that we briefly deliberate on the binding of enzymes to magnetic nanocomposites and the corresponding enzymatic catalysis. Finally, we draw conclusions and present a future outlook for the further development of new catalytic systems which are immobilised onto magnetic nanoparticles. PMID:28344220

Nanoparticle layer deposition for highly controlled multilayer formation based on high-coverage monolayers of nanoparticles

International Nuclear Information System (INIS)

Liu, Yue; Williams, Mackenzie G.; Miller, Timothy J.; Teplyakov, Andrew V.

2016-01-01

This paper establishes a strategy for chemical deposition of functionalized nanoparticles onto solid substrates in a layer-by-layer process based on self-limiting surface chemical reactions leading to complete monolayer formation within the multilayer system without any additional intermediate layers — nanoparticle layer deposition (NPLD). This approach is fundamentally different from previously established traditional layer-by-layer deposition techniques and is conceptually more similar to well-known atomic and molecular layer deposition processes. The NPLD approach uses efficient chemical functionalization of the solid substrate material and complementary functionalization of nanoparticles to produce a nearly 100% coverage of these nanoparticles with the use of “click chemistry”. Following this initial deposition, a second complete monolayer of nanoparticles is deposited using a copper-catalyzed “click reaction” with the azide-terminated silica nanoparticles of a different size. This layer-by-layer growth is demonstrated to produce stable covalently-bound multilayers of nearly perfect structure over macroscopic solid substrates. The formation of stable covalent bonds is confirmed spectroscopically and the stability of the multilayers produced is tested by sonication in a variety of common solvents. The 1-, 2- and 3-layer structures are interrogated by electron microscopy and atomic force microscopy and the thickness of the multilayers formed is fully consistent with that expected for highly efficient monolayer formation with each cycle of growth. This approach can be extended to include a variety of materials deposited in a predesigned sequence on different substrates with a highly conformal filling. - Highlights: • We investigate the formation of high-coverage monolayers of nanoparticles. • We use “click chemistry” to form these monolayers. • We form multiple layers based on the same strategy. • We confirm the formation of covalent bonds

Effects of Surface Epitope Coverage on the Sensitivity of Displacement Assays that Employ Modified Nanoparticles: Using Bisphenol A as a Model Analyte

Directory of Open Access Journals (Sweden)

Yang Lu

2016-08-01

Full Text Available With the ever-increasing use of nanoparticles in immunosensors, a fundamental study on the effect of epitope density is presented herein, with a small molecule epitope, on the performance of the displacement assay format in an enzyme-linked immunosorbent assay (ELISA. Thiolated bisphenol A (BPA functionalized gold nanoparticles (cysBPAv-AuNPs and specific anti-BPA antibodies are employed for this purpose. It is shown that the displacement of cysBPAv-AuNPs bound to the immobilized antibodies was influenced by both the avidity of bound cysBPAv-AuNPs and the concentration of free BPA to displace it. The importance of surface epitope density was that it changed the number of epitopes in close proximity to the antibody-binding site. This then influenced the avidity of cysBPAv-AuNPs bound to the immobilized antibody. Furthermore, the molar epitope concentration in an assay appears to affect the degree of antibody binding site saturation. Controlling surface epitope density of the functionalized nanoparticles and molar epitope concentration in an assay leads to a decrease of the concentration of free BPA required to displace the bound cysBPAv-AuNP, and hence better assay performance with regards to the D50 value and dynamic range in the displacement assay.

Phase II Study of Neoadjuvant Anthracycline-Based Regimens Combined With Nanoparticle Albumin-Bound Paclitaxel and Trastuzumab for Human Epidermal Growth Factor Receptor 2-Positive Operable Breast Cancer.

Science.gov (United States)

Tanaka, Satoru; Iwamoto, Mitsuhiko; Kimura, Kosei; Matsunami, Nobuki; Morishima, Hirotaka; Yoshidome, Katsuhide; Nomura, Takashi; Morimoto, Takashi; Yamamoto, Daigo; Tsubota, Yu; Kobayashi, Toshihiro; Uchiyama, Kazuhisa

2015-06-01

We treated patients with operable human epidermal growth factor receptor 2-positive breast cancer with neoadjuvant anthracycline regimens followed by nanoparticle albumin-bound paclitaxel plus trastuzumab. Of the 44 patients, 49% achieved a pathologic complete response (pCR). The pCR rate was 36% and 71% in the patients with estrogen receptor-positive and -negative cancer, respectively. Neoadjuvant therapy using this combination appears to be effective and safe. Introduction: Neoadjuvant chemotherapy plus trastuzumab. Neoadjuvant chemotherapy plus trastuzumab results in a 30% to 50% pathologic complete response (pCR) rate in human epidermal growth factor receptor 2 (HER2)-positive breast cancer and has been associated with improved therapeutic outcomes. Thus, the pCR rate can be useful in evaluating novel agents in this patient population. Nanoparticle albumin-bound (nab)-paclitaxel (PTX) can reduce the toxicity of PTX while maintaining its efficacy. The present study evaluated the activity and safety of nab-PTX as a neoadjuvant treatment of HER2(+) breast cancer. We treated patients with stage I to IIIA breast cancer using neoadjuvant epirubicin/cyclophosphamide (EC) or 5-fluorouracil/epirubicin/cyclophosphamide every 3 weeks (q3w) for 4 cycles, followed by nab-PTX (260 mg/m(2)) plus trastuzumab q3w for 4 cycles. The primary endpoint was the pCR rate. The secondary endpoints included the clinical response rate, disease-free survival, pathologic response rate (defined as pCR or minimal residual invasive disease only in the breast), breast-conserving surgery rate, and safety. Forty-six patients were enrolled. One patient met the exclusion criteria because of the coexistence of another malignant disease; therefore, we evaluated 45 patients in the entire study. One patient experienced rapid disease progression during EC therapy, leaving 44 patients evaluable for nab-PTX treatment. Of the 45 patients, 49% achieved a pCR. The pCR rate was 36% and 71% in those with

Antibacterial surfaces by adsorptive binding of polyvinyl-sulphonate-stabilized silver nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Vasilev, Krasimir; Sah, Vasu R; Goreham, Renee V; Short, Robert D [Mawson Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, Adelaide, SA 5095 (Australia); Ndi, Chi; Griesser, Hans J, E-mail: Krasimir.vasilev@unisa.edu.au [Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095 (Australia)

2010-05-28

This paper presents a novel and facile method for the generation of efficient antibacterial coatings which can be applied to practically any type of substrate. Silver nanoparticles were stabilized with an adsorbed surface layer of polyvinyl sulphonate (PVS). This steric layer provided excellent colloidal stability, preventing aggregation over periods of months. PVS-coated silver nanoparticles were bound onto amine-containing surfaces, here produced by deposition of an allylamine plasma polymer thin film onto various substrates. SEM imaging showed no aggregation upon surface binding of the nanoparticles; they were well dispersed on amine surfaces. Such nanoparticle-coated surfaces were found to be effective in preventing attachment of Staphylococcus epidermidis bacteria and also in preventing biofilm formation. Combined with the ability of plasma polymerization to apply the thin polymeric binding layer onto a wide range of materials, this method appears promising for the fabrication of a wide range of infection-resistant biomedical devices.

Synthesis and characterization of thiolated pectin stabilized gold coated magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arora, Varun, E-mail: varun.arora3986@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India); Sood, Ankur, E-mail: ankursood02@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India); Shah, Jyoti, E-mail: shah.jyoti1@gmail.com [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Kotnala, R.K., E-mail: rkkotnala@nplindia.org [National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012 (India); Jain, Tapan K., E-mail: tapankjain@gmail.com [University School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Sector 16-C, Dwarka, New Delhi 110078 (India)

2016-04-15

Core–shell nanoparticles, magnetic core and gold shell, were synthesized by reduction of gold chloride on the surface of magnetic nanoparticles; using tyrosine as a reducing agent. The formation of gold shell on magnetic nanoparticles was confirmed by X-ray diffraction (XRD) and UV-Visible spectroscopy. The core–shell nanoparticles (CSn) were conjugated with thiolated pectin to form a stable aqueous dispersion. The hydrodynamic size of thiolated pectin stabilized core–shell nanoparticles (TP-CSn) measured by Dynamic light scattering (DLS) was 160.5 nm with a poly dispersity index (PDI) of 0.302, whereas the mean particle size of TP-CSn calculated by high resolution transmission electron microscopy (HRTEM) was 10.8 ± 2.7 nm. The value of zeta potential for TP-CSn was −13.6 mV. There was a decrease in the value of saturation magnetization upon formation of the gold shell on magnetic nanoparticles. The amount of thiolated pectin bound to the surface of core–shell nanoparticles, calculated using Thermogravimetric analysis (TGA), was 6% of sample weight. - Highlights: • Use of side group of tyrosine (phenol) as a pH dependent reducing agent to synthesize gold coated magnetic nanoparticles. • Successful coating of gold shell on magnetic nanoparticles core. • Synthesis of thiolated pectin and stabilization of aqueous dispersion of core–shell nanoparticles with thiolated pectin. • The superparamagnetic behaviour of magnetic nanoparticles is retained after shell formation.

Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

International Nuclear Information System (INIS)

Kumar, Nikhil; Upadhyay, Lata Sheo Bachan

2016-01-01

Highlights: • A facile and eco-friendly method for the synthesis of L-cysteine functionalized copper nanoparticles is reported. • Synthesis of Highly stable L-cysteine functionalized copper nanoparticles (∼40 nm) was done in an aqueous medium. • FTIR analysis shows that L-cysteine bound to the nanoparticle surface via thiol group. - Abstract: A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month

Facile and green synthesis of highly stable L-cysteine functionalized copper nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kumar, Nikhil, E-mail: nkumar.phd2011.bt@nitrr.ac.in; Upadhyay, Lata Sheo Bachan, E-mail: contactlataupadhyay@gmail.com

2016-11-01

Highlights: • A facile and eco-friendly method for the synthesis of L-cysteine functionalized copper nanoparticles is reported. • Synthesis of Highly stable L-cysteine functionalized copper nanoparticles (∼40 nm) was done in an aqueous medium. • FTIR analysis shows that L-cysteine bound to the nanoparticle surface via thiol group. - Abstract: A simple eco-friendly method for L-cysteine capped copper nanoparticles (CCNPs) synthesis in aqueous solution has been developed. Glucose and L-cysteine were used as reducing agent and capping/functionalizing agent, respectively. Different parameters such as capping agent concentration, pH, reaction temperature, and reducing agent concentration were optimized during the synthesis. The L-cysteine capped copper nanoparticle were characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, Particle size and zeta potential analyser, and high resolution transmission electron microscopy. Spherical shaped cysteine functionalized/capped copper nanoparticles with an average size of 40 nm were found to be highly stable at room temperature (RT) for a period of 1 month.

One-Dimensional Brownian Motion of Charged Nanoparticles along Microtubules: A Model System for Weak Binding Interactions

OpenAIRE

Minoura, Itsushi; Katayama, Eisaku; Sekimoto, Ken; Muto, Etsuko

2010-01-01

Various proteins are known to exhibit one-dimensional Brownian motion along charged rodlike polymers, such as microtubules (MTs), actin, and DNA. The electrostatic interaction between the proteins and the rodlike polymers appears to be crucial for one-dimensional Brownian motion, although the underlying mechanism has not been fully clarified. We examined the interactions of positively-charged nanoparticles composed of polyacrylamide gels with MTs. These hydrophilic nanoparticles bound to MTs ...

Synthesis and Characterization of Fe3O4 Magnetic Nanoparticles Coated with Carboxymethyl Chitosan Grafted Sodium Methacrylate

Directory of Open Access Journals (Sweden)

S. Asgari

2014-01-01

Full Text Available N-sodium acrylate-O-carboxymethyl chitosan [CMCH-g-PAA(Na] bound Fe3O4 nanoparticles were developed as a novel magnetic nanoparticles with an ionic structure that can be potentially used in many fields. CMCH-g-PAA (Na was obtained by grafting of sodium polyacrylate on O-carboxymethyl chitosan, which is an amphiphilic polyelectrolyte with the biocompatibility and biodegradability properties. According to the great interest for improving the stability of Fe3O4 nanoparticles, CMCH-g-PAA (Na was used as a stabilizer to prepare a well dispersed suspension of magnetic nanoparticle According to the results,the presence of CMCH-g-PAA(Na could eliminate agglomeration of magnetic nanoparticles without destroying the superparamagnetic  properties

Multi-photon excited luminescence of magnetic FePt core-shell nanoparticles.

Science.gov (United States)

Seemann, K M; Kuhn, B

2014-07-01

We present magnetic FePt nanoparticles with a hydrophilic, inert, and biocompatible silico-tungsten oxide shell. The particles can be functionalized, optically detected, and optically manipulated. To show the functionalization the fluorescent dye NOPS was bound to the FePt core-shell nanoparticles with propyl-triethoxy-silane linkers and fluorescence of the labeled particles were observed in ethanol (EtOH). In aqueous dispersion the NOPS fluorescence is quenched making them invisible using 1-photon excitation. However, we observe bright luminescence of labeled and even unlabeled magnetic core-shell nanoparticles with multi-photon excitation. Luminescence can be detected in the near ultraviolet and the full visible spectral range by near infrared multi-photon excitation. For optical manipulation, we were able to drag clusters of particles, and maybe also single particles, by a focused laser beam that acts as optical tweezers by inducing an electric dipole in the insulated metal nanoparticles. In a first application, we show that the luminescence of the core-shell nanoparticles is bright enough for in vivo multi-photon imaging in the mouse neocortex down to cortical layer 5.

Comparison and functionalization study of microemulsion-prepared magnetic iron oxide nanoparticles.

Science.gov (United States)

Okoli, Chuka; Sanchez-Dominguez, Margarita; Boutonnet, Magali; Järås, Sven; Civera, Concepción; Solans, Conxita; Kuttuva, Gunaratna Rajarao

2012-06-05

Magnetic iron oxide nanoparticles (MION) for protein binding and separation were obtained from water-in-oil (w/o) and oil-in-water (o/w) microemulsions. Characterization of the prepared nanoparticles have been performed by TEM, XRD, SQUID magnetometry, and BET. Microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) with sizes ranging from 2 to 10 nm were obtained. Study on the magnetic properties at 300 K shows a large increase of the magnetization ~35 emu/g for w/o-ME-MION with superparamagnetic behavior and nanoscale dimensions in comparison with o/w-ME-MION (10 emu/g) due to larger particle size and anisotropic property. Moringa oleifera coagulation protein (MOCP) bound w/o- and o/w-ME-MION showed an enhanced performance in terms of coagulation activity. A significant interaction between the magnetic nanoparticles and the protein can be described by changes in fluorescence emission spectra. Adsorbed protein from MOCP is still retaining its functionality even after binding to the nanoparticles, thus implying the extension of this technique for various applications.

Virial Expansion Bounds

Science.gov (United States)

Tate, Stephen James

2013-10-01

In the 1960s, the technique of using cluster expansion bounds in order to achieve bounds on the virial expansion was developed by Lebowitz and Penrose (J. Math. Phys. 5:841, 1964) and Ruelle (Statistical Mechanics: Rigorous Results. Benjamin, Elmsford, 1969). This technique is generalised to more recent cluster expansion bounds by Poghosyan and Ueltschi (J. Math. Phys. 50:053509, 2009), which are related to the work of Procacci (J. Stat. Phys. 129:171, 2007) and the tree-graph identity, detailed by Brydges (Phénomènes Critiques, Systèmes Aléatoires, Théories de Jauge. Les Houches 1984, pp. 129-183, 1986). The bounds achieved by Lebowitz and Penrose can also be sharpened by doing the actual optimisation and achieving expressions in terms of the Lambert W-function. The different bound from the cluster expansion shows some improvements for bounds on the convergence of the virial expansion in the case of positive potentials, which are allowed to have a hard core.

Upper bounds on superpartner masses from upper bounds on the Higgs boson mass.

Science.gov (United States)

Cabrera, M E; Casas, J A; Delgado, A

2012-01-13

The LHC is putting bounds on the Higgs boson mass. In this Letter we use those bounds to constrain the minimal supersymmetric standard model (MSSM) parameter space using the fact that, in supersymmetry, the Higgs mass is a function of the masses of sparticles, and therefore an upper bound on the Higgs mass translates into an upper bound for the masses for superpartners. We show that, although current bounds do not constrain the MSSM parameter space from above, once the Higgs mass bound improves big regions of this parameter space will be excluded, putting upper bounds on supersymmetry (SUSY) masses. On the other hand, for the case of split-SUSY we show that, for moderate or large tanβ, the present bounds on the Higgs mass imply that the common mass for scalars cannot be greater than 10(11)  GeV. We show how these bounds will evolve as LHC continues to improve the limits on the Higgs mass.

Electrochemical Nanoparticle-Enzyme Sensors for Screening Bacterial Contamination in Drinking Water

Science.gov (United States)

Chen, Juhong; Jiang, Ziwen; Ackerman, Jonathan D.; Yazdani, Mahdieh; Hou, Singyuk

2015-01-01

Traditional plating and culturing methods used to quantify bacteria commonly require hours to days from sampling to results. We present here a simple, sensitive and rapid electrochemical method for bacteria detection in drinking water based on gold nanoparticle-enzyme complexes. The gold nanoparticles were functionalized with positively charged quaternary amine headgroups that could bind to enzymes through electrostatic interactions, resulting in inhibition of enzymatic activity. In the presence of bacteria, the nanoparticles released from the enzymes and preferentially bound to the bacteria, resulting in an increase in enzyme activity, releasing a redox-active phenol from the substrate. We employed this strategy for the electrochemical sensing of Escherichia coli and Staphylococcus aureus, resulting in a rapid detection (<1h) with high sensitivity (102 CFU·mL−1). PMID:26042607

The DMM Bound

DEFF Research Database (Denmark)

Emiris, Ioannis Z.; Mourrain, Bernard; Tsigaridas, Elias

2010-01-01

) resultant by means of mixed volume, as well as recent advances on aggregate root bounds for univariate polynomials, and are applicable to arbitrary positive dimensional systems. We improve upon Canny's gap theorem [7] by a factor of O(dn-1), where d bounds the degree of the polynomials, and n is the number...... bound on the number of steps that subdivision-based algorithms perform in order to isolate all real roots of a polynomial system. This leads to the first complexity bound of Milne's algorithm [22] in 2D....

On the Hopping Efficiency of Nanoparticles in the Electron Transfer across Self‐Assembled Monolayers

DEFF Research Database (Denmark)

Liu, Feng; Khan, Kamran; Liang, Jing‐Hong

2013-01-01

Redox reactions of solvated molecular species at gold‐electrode surfaces modified by electrochemically inactive self‐assembled molecular monolayers (SAMs) are found to be activated by introducing Au nanoparticles (NPs) covalently bound to the SAM to form a reactive Au–alkanedithiol–NP–molecule hy...

Organically bound tritium

International Nuclear Information System (INIS)

Diabate, S.; Strack, S.

1993-01-01

Tritium released into the environment may be incorporated into organic matter. Organically bound tritium in that case will show retention times in organisms that are considerably longer than those of tritiated water which has significant consequences on dose estimates. This article reviews the most important processes of organically bound tritium production and transport through food networks. Metabolic reactions in plant and animal organisms with tritiated water as a reaction partner are of great importance in this respect. The most important production process, in quantitative terms, is photosynthesis in green plants. The translocation of organically bound tritium from the leaves to edible parts of crop plants should be considered in models of organically bound tritium behavior. Organically bound tritium enters the human body on several pathways, either from the primary producers (vegetable food) or at a higher tropic level (animal food). Animal experiments have shown that the dose due to ingestion of organically bound tritium can be up to twice as high as a comparable intake of tritiated water in gaseous or liquid form. In the environment, organically bound tritium in plants and animals is often found to have higher specific tritium concentrations than tissue water. This is not due to some tritium enrichment effects but to the fact that no equilibrium conditions are reached under natural conditions. 66 refs

Physical Uncertainty Bounds (PUB)

Energy Technology Data Exchange (ETDEWEB)

Vaughan, Diane Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Preston, Dean L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-03-19

This paper introduces and motivates the need for a new methodology for determining upper bounds on the uncertainties in simulations of engineered systems due to limited fidelity in the composite continuum-level physics models needed to simulate the systems. We show that traditional uncertainty quantification methods provide, at best, a lower bound on this uncertainty. We propose to obtain bounds on the simulation uncertainties by first determining bounds on the physical quantities or processes relevant to system performance. By bounding these physics processes, as opposed to carrying out statistical analyses of the parameter sets of specific physics models or simply switching out the available physics models, one can obtain upper bounds on the uncertainties in simulated quantities of interest.

A novel method for synthesis of {sup 56}Co-radiolabelled silica nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Cydzik, I. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy); Bilewicz, A. [Institute of Nuclear Chemistry and Technology (Poland); Abbas, K. [Institute for Transuranium Elements (Ispra Site), European Commission, Joint Research Centre (Italy); Simonelli, F.; Bulgheroni, A.; Holzwarth, U., E-mail: uwe.holzwarth@jrc.ec.europa.eu; Gibson, N. [Institute for Health and Consumer Protection, European Commission, Joint Research Centre (Italy)

2012-10-15

A method for synthesis of radiolabelled amorphous silica nanoparticles is presented. The method is based on the well-known Stoeber process with the exception that {sup 56}Co radiotracer is introduced into one of the precursor materials prior to the initiation of the nanoparticle synthesis. The {sup 56}Co was prepared by proton irradiation of an iron foil, followed by dissolution in hydrochloric acid and {sup 56}Co/Fe radiochemical separation. In order to determine the residual Fe in the {sup 56}Co radiotracer solution, ICP-MS measurements were performed. Nanoparticles in the size range 20-100 nm were synthesised and characterised by gamma spectrometry, ICP-MS, XRD, DLS, and Zeta potential measurement. It was shown that the size and Zeta potential of the nanoparticles was roughly the same following synthesis with or without added {sup 56}Co, and in both cases, the structure was that of amorphous silica. It was found that 99.5 % of the {sup 56}Co was bound into the nanoparticles during synthesis, and centrifugation experiments confirmed that the radiolabels were stably incorporated into the silica matrix.

Zinc-decorated silica-coated magnetic nanoparticles for protein binding and controlled release.

Science.gov (United States)

Bele, Marjan; Hribar, Gorazd; Campelj, Stanislav; Makovec, Darko; Gaberc-Porekar, Vladka; Zorko, Milena; Gaberscek, Miran; Jamnik, Janko; Venturini, Peter

2008-05-01

The aim of this study was to be able to reversibly bind histidine-rich proteins to the surface of maghemite magnetic nanoparticles via coordinative bonding using Zn ions as the anchoring points. We showed that in order to adsorb Zn ions on the maghemite, the surface of the latter needs to be modified. As silica is known to strongly adsorb zinc ions, we chose to modify the maghemite nanoparticles with a nanometre-thick silica layer. This layer appeared to be thin enough for the maghemite nanoparticles to preserve their superparamagnetic nature. As a model the histidine-rich protein bovine serum albumin (BSA) was used. The release of the BSA bound to Zn-decorated silica-coated maghemite nanoparticles was analysed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). We demonstrated that the bonding of the BSA to such modified magnetic nanoparticles is highly reversible and can be controlled by an appropriate change of the external conditions, such as a pH decrease or the presence/supply of other chelating compounds.

Biogenic Nanoparticles from Schwanniomyces occidentalis NCIM 3459: Mechanistic Aspects and Catalytic Applications.

Science.gov (United States)

Mohite, Pallavi; Apte, Mugdha; Kumar, Ameeta Ravi; Zinjarde, Smita

2016-06-01

When cells of Schwanniomyces occidentalis NCIM 3459 were incubated with 1 mM tetrachloroauric acid (HAuCl4) or silver nitrate (AgNO3), cell-associated nanoparticles were obtained. Their presence was confirmed by scanning electron microscope observations. The cell-free supernatant (CFS) of the yeast mediated the synthesis of gold nanoparticles. On account of the difficulties associated with the use of cell-bound nanoparticles, further work was restricted to extracellular nanoparticles. It was hypothesized that the CFS contained thermostable biomolecule(s) that mediated metal reduction reactions. Extraction of the CFS with chloroform/methanol (2:1) and subsequent separation by preparative thin layer chromatography led to the activity-guided purification of a glycolipid. The glycolipid was hydrolyzed and the glycone (glucose) and aglycone components (palmitic acid and oleic acid) were identified by gas chromatography-mass spectrometry. The purified glycolipid mediated the synthesis of gold and silver nanoparticles that were characterized by using an X-ray diffractometer and transmission electron microscope (TEM). The extracellular nanoparticles displayed catalytic activities and reduced 4-nitroaniline to benzene-1,4-diamine. This paper thus highlights nanoparticle synthesis by a hitherto unreported yeast culture, identifies the biomolecules involved in the process, and describes a potential application of the nanostructures.

Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces

Science.gov (United States)

Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei

2016-06-01

Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent

Highly stabilized gadolinium chelates functionalized on metal nanoparticles as magnetic resonance imaging contrast agent

Science.gov (United States)

Siddiqui, Talha S.

Magnetic resonance imaging (MRI) is a non-invasive method for imaging and diagnosing tissue damage, organ function and the vascular system. Magnevist(TM) a complex of diethylenetriaminepentaacetic acid (DTPA) and Gd3+ is a clinically approved contrast agent for MRI. A derivative of DTPA was formed by the addition of two cysteine groups (DTPA-L-Cys) through amide linkage. The Gd complex of this ligand bonds with the silver surfaces through the cysteine thiols. GdDTPA-L-Cys was bound to ˜10nm diameter Ag nanoparticles for use as a multifunctional MRI contrast agent. The ligand and complex were characterized by 1H and 13C NMR, ESI-MS and IR spectroscopy. The silver construct was characterized by TEM, TGA and UV-Vis absorption spectra. The per metal complex r1 relaxivity of GdDTPA-L-Cys{Ag} greater than that of Magnavist(TM) with the same molarity for both compounds. The synthesis of a DTPA derivative is described that allows it to bind to silver or gold nanoparticles through a single thiol linkage (DTPASH). The resulting Gd complex, GdDTPASH, was bound to Ag nanoparticles to create a single monolayer on the surface. The construct was further stabilized in buffered solution with the addition of a thiolated PEG chain. The highly stabilized nanoparticle construct delivers a high payload of Gd compelex and is an effective T1 brightening agent. The production of this type of construct opens the way for engineered multimodal MRI contrast agents.

Chitosan-Coated Magnetic Nanoparticles with Low Chitosan Content Prepared in One-Step

Directory of Open Access Journals (Sweden)

Yolanda Osuna

2012-01-01

Full Text Available Chitosan-coated magnetic nanoparticles (CMNP were obtained at 50°C in a one-step method comprising coprecipitation in the presence of low chitosan content. CMNP showed high magnetization and superparamagnetism. They were composed of a core of 9.5 nm in average diameter and a very thin chitosan layer in accordance with electron microscopy measurements. The results from Fourier transform infrared spectrometry demonstrated that CMNP were obtained and those from thermogravimetric analysis allowed to determine that they were composed of 95 wt% of magnetic nanoparticles and 5 wt% of chitosan. 67% efficacy in the Pb+2 removal test indicated that only 60% of amino groups on CMNP surface bound to Pb, probably due to some degree of nanoparticle flocculation during the redispersion. The very low weight ratio chitosan to magnetic nanoparticles obtained in this study, 0.053, and the high yield of the precipitation reactions (≈97% are noticeable.

Effect of surface charge on the cellular uptake of fluorescent magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kralj, Slavko, E-mail: slavko.kralj@ijs.si [Jozef Stefan Institute, Department for Materials Synthesis (Slovenia); Rojnik, Matija [University of Ljubljana, Faculty of Pharmacy (Slovenia); Romih, Rok [University of Ljubljana, Faculty of Medicine, Institute of Cell Biology (Slovenia); Jagodic, Marko [Institute of Mathematics, Physics and Mechanics (Slovenia); Kos, Janko [University of Ljubljana, Faculty of Pharmacy (Slovenia); Makovec, Darko [Jozef Stefan Institute, Department for Materials Synthesis (Slovenia)

2012-10-15

We report on the nanoparticle uptake into MCF10A neoT and PC-3 cells using flow cytometry, confocal microscopy, SQUID magnetometry, and transmission electron microscopy. The aim was to evaluate the influence of the nanoparticles' surface charge on the uptake efficiency. The surface of the superparamagnetic, silica-coated, maghemite nanoparticles was modified using amino functionalization for the positive surface charge (CNPs), and carboxyl functionalization for the negative surface charge (ANPs). The CNPs and ANPs exhibited no significant cytotoxicity in concentrations up to 500 {mu}g/cm{sup 3} in 24 h. The CNPs, bound to a plasma membrane, were intensely phagocytosed, while the ANPs entered cells through fluid-phase endocytosis in a lower internalization degree. The ANPs and CNPs were shown to be co-localized with a specific lysosomal marker, thus confirming their presence in lysosomes. We showed that tailoring the surface charge of the nanoparticles has a great impact on their internalization.

Biogenic synthesis and characterization of gold nanoparticles by Escherichia coli K12 and its heterogeneous catalysis in degradation of 4-nitrophenol

Science.gov (United States)

Srivastava, Sarvesh Kumar; Yamada, Ryosuke; Ogino, Chiaki; Kondo, Akihiko

2013-02-01

Room-temperature extracellular biosynthesis of gold nanoparticles (Au NPs) was achieved using Escherichia coli K12 cells without the addition of growth media, pH adjustments or inclusion of electron donors/stabilizing agents. The resulting nanoparticles were analysed by ultraviolet-visible (UV-vis) spectrophotometry, atomic force microscopy, transmission electron microscopy and X-ray diffraction. Highly dispersed gold nanoplates were achieved in the order of around 50 nm. Further, the underlying mechanism was found to be controlled by certain extracellular membrane-bound proteins, which was confirmed by Fourier transformation-infrared spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis. We observed that certain membrane-bound peptides are responsible for reduction and subsequent stabilization of Au NPs (confirmed by zeta potential analysis). Upon de-activation of these proteins, no nanoparticle formation was observed. Also, we prepared a novel biocatalyst with Au NPs attached to the membrane-bound fraction of E. coli K12 cells serving as an efficient heterogeneous catalyst in complete reduction of 4-nitrophenol in the presence of NaBH4 which was studied with UV-vis spectroscopy. This is the first report on bacterial membrane-Au NP nanobiocomposite serving as an efficient heterogeneous catalyst in complete reduction of nitroaromatic pollutant in water.

Covalently bound DNA on naked iron oxide nanoparticles: Intelligent colloidal nano-vector for cell transfection.

Science.gov (United States)

Magro, Massimiliano; Martinello, Tiziana; Bonaiuto, Emanuela; Gomiero, Chiara; Baratella, Davide; Zoppellaro, Giorgio; Cozza, Giorgio; Patruno, Marco; Zboril, Radek; Vianello, Fabio

2017-11-01

Conversely to common coated iron oxide nanoparticles, novel naked surface active maghemite nanoparticles (SAMNs) can covalently bind DNA. Plasmid (pDNA) harboring the coding gene for GFP was directly chemisorbed onto SAMNs, leading to a novel DNA nanovector (SAMN@pDNA). The spontaneous internalization of SAMN@pDNA into cells was compared with an extensively studied fluorescent SAMN derivative (SAMN@RITC). Moreover, the transfection efficiency of SAMN@pDNA was evaluated and explained by computational model. SAMN@pDNA was prepared and characterized by spectroscopic and computational methods, and molecular dynamic simulation. The size and hydrodynamic properties of SAMN@pDNA and SAMN@RITC were studied by electron transmission microscopy, light scattering and zeta-potential. The two nanomaterials were tested by confocal scanning microscopy on equine peripheral blood-derived mesenchymal stem cells (ePB-MSCs) and GFP expression by SAMN@pDNA was determined. Nanomaterials characterized by similar hydrodynamic properties were successfully internalized and stored into mesenchymal stem cells. Transfection by SAMN@pDNA occurred and GFP expression was higher than lipofectamine procedure, even in the absence of an external magnetic field. A computational model clarified that transfection efficiency can be ascribed to DNA availability inside cells. Direct covalent binding of DNA on naked magnetic nanoparticles led to an extremely robust gene delivery tool. Hydrodynamic and chemical-physical properties of SAMN@pDNA were responsible of the successful uptake by cells and of the efficiency of GFP gene transfection. SAMNs are characterized by colloidal stability, excellent cell uptake, persistence in the host cells, low toxicity and are proposed as novel intelligent DNA nanovectors for efficient cell transfection. Copyright © 2017 Elsevier B.V. All rights reserved.

Lanthanide-based NMR: a tool to investigate component distribution in mixed-monolayer-protected nanoparticles.

Science.gov (United States)

Guarino, Gaetano; Rastrelli, Federico; Scrimin, Paolo; Mancin, Fabrizio

2012-05-02

Gd(3+) ions, once bound to the monolayer of organic molecules coating the surface of gold nanoparticles, produce a paramagnetic relaxation enhancement (PRE) that broadens and eventually cancels the signals of the nuclear spins located nearby (within 1.6 nm distance). In the case of nanoparticles coated with mixed monolayers, the signals arising from the different coating molecules experience different PRE, depending on their distance from the binding site. As a consequence, observation of the signal broadening patterns provides direct information on the monolayer organization. © 2012 American Chemical Society

Modeling and sensitivity analysis on the transport of aluminum oxide nanoparticles in saturated sand: effects of ionic strength, flow rate, and nanoparticle concentration.

Science.gov (United States)

Rahman, Tanzina; Millwater, Harry; Shipley, Heather J

2014-11-15

Aluminum oxide nanoparticles have been widely used in various consumer products and there are growing concerns regarding their exposure in the environment. This study deals with the modeling, sensitivity analysis and uncertainty quantification of one-dimensional transport of nano-sized (~82 nm) aluminum oxide particles in saturated sand. The transport of aluminum oxide nanoparticles was modeled using a two-kinetic-site model with a blocking function. The modeling was done at different ionic strengths, flow rates, and nanoparticle concentrations. The two sites representing fast and slow attachments along with a blocking term yielded good agreement with the experimental results from the column studies of aluminum oxide nanoparticles. The same model was used to simulate breakthrough curves under different conditions using experimental data and calculated 95% confidence bounds of the generated breakthroughs. The sensitivity analysis results showed that slow attachment was the most sensitive parameter for high influent concentrations (e.g. 150 mg/L Al2O3) and the maximum solid phase retention capacity (related to blocking function) was the most sensitive parameter for low concentrations (e.g. 50 mg/L Al2O3). Copyright © 2014 Elsevier B.V. All rights reserved.

78 FR 18326 - Agency Information Collection Activities; Comment Request; Upward Bound and Upward Bound Math...

Science.gov (United States)

2013-03-26

...; Comment Request; Upward Bound and Upward Bound Math Science Annual Performance Report AGENCY: The Office... considered public records. Title of Collection: Upward Bound and Upward Bound Math Science Annual Performance...) and Upward Bound Math and Science (UBMS) Programs. The Department is requesting a new APR because of...

Universal bounds on current fluctuations.

Science.gov (United States)

Pietzonka, Patrick; Barato, Andre C; Seifert, Udo

2016-05-01

For current fluctuations in nonequilibrium steady states of Markovian processes, we derive four different universal bounds valid beyond the Gaussian regime. Different variants of these bounds apply to either the entropy change or any individual current, e.g., the rate of substrate consumption in a chemical reaction or the electron current in an electronic device. The bounds vary with respect to their degree of universality and tightness. A universal parabolic bound on the generating function of an arbitrary current depends solely on the average entropy production. A second, stronger bound requires knowledge both of the thermodynamic forces that drive the system and of the topology of the network of states. These two bounds are conjectures based on extensive numerics. An exponential bound that depends only on the average entropy production and the average number of transitions per time is rigorously proved. This bound has no obvious relation to the parabolic bound but it is typically tighter further away from equilibrium. An asymptotic bound that depends on the specific transition rates and becomes tight for large fluctuations is also derived. This bound allows for the prediction of the asymptotic growth of the generating function. Even though our results are restricted to networks with a finite number of states, we show that the parabolic bound is also valid for three paradigmatic examples of driven diffusive systems for which the generating function can be calculated using the additivity principle. Our bounds provide a general class of constraints for nonequilibrium systems.

Production of BSA-poly(ethyl cyanoacrylate) nanoparticles as a coating material that improves wetting property.

Science.gov (United States)

Kim, S; Evans, K; Biswas, A

2013-07-01

Alkyl cyanoacrylates have long been used for the synthesis of colloidal nanoparticles. In the involved polymerization reaction, hydroxyl ions derived from dissociation of water have been used as an initiator. In the current research, an animal protein, bovine serum albumin (BSA) molecules were utilized as initiator for the polymerization. Following this reaction scheme, hydrophobic poly(ethyl cyanoacrylate)s were covalently bound to BSA, which is hydrophilic. Therefore, the resultant copolymer was amphiphilic in nature, and formed nanoparticles in the reaction medium. The suspension containing these nanoparticles showed an excellent coating capability on the surface of hydrophobic materials. A simple spray coating changed the wetting property of the material instantly and dramatically. Published by Elsevier B.V.

Quivers of Bound Path Algebras and Bound Path Coalgebras

Directory of Open Access Journals (Sweden)

Dr. Intan Muchtadi

2010-09-01

Full Text Available bras and coalgebras can be represented as quiver (directed graph, and from quiver we can construct algebras and coalgebras called path algebras and path coalgebras. In this paper we show that the quiver of a bound path coalgebra (resp. algebra is the dual quiver of its bound path algebra (resp. coalgebra.

Binding assays with streptavidin-functionalized superparamagnetic nanoparticles and biotinylated analytes using fluxgate magnetorelaxometry

International Nuclear Information System (INIS)

Heim, Erik; Ludwig, Frank; Schilling, Meinhard

2009-01-01

Binding assays based on the magnetorelaxation of superparamagnetic nanoparticles as markers are presented utilizing a differential fluxgate system. As ligand and receptor, streptavidin and biotin, respectively, are used. Superparamagnetic nanoparticles are functionalized with streptavidin and bound to two types of biotinylated analytes: agarose beads and bovine serum (BSA) proteins. The size difference of the two analytes causes a different progress of the reaction. As a consequence, the analysis of the relaxation signal is carried out dissimilarly for the two analytes. In addition, we studied the reaction kinetics of the two kinds of analytes with the fluxgate system.

Targeted Delivery of Glucan Particle Encapsulated Gallium Nanoparticles Inhibits HIV Growth in Human Macrophages

Directory of Open Access Journals (Sweden)

Ernesto R. Soto

2016-01-01

Full Text Available Glucan particles (GPs are hollow, porous 3–5 μm microspheres derived from the cell walls of Baker’s yeast (Saccharomyces cerevisiae. The 1,3-β-glucan outer shell provides for receptor-mediated uptake by phagocytic cells expressing β-glucan receptors. GPs have been used for macrophage-targeted delivery of a wide range of payloads (DNA, siRNA, protein, small molecules, and nanoparticles encapsulated inside the hollow GPs or bound to the surface of chemically derivatized GPs. Gallium nanoparticles have been proposed as an inhibitory agent against HIV infection. Here, macrophage targeting of gallium using GPs provides for more efficient delivery of gallium and inhibition of HIV infection in macrophages compared to free gallium nanoparticles.

Shot-noise dominant regime of a nanoparticle in a laser beam

Science.gov (United States)

Zhong, Changchun; Robicheaux, Francis

2017-04-01

The technique of laser levitation of nanoparticles has become increasingly promising in the study of cooling and controlling mesoscopic quantum systems. Unlike a mechanical system, the levitated nanoparticle is less exposed to thermalization and decoherence due to the absence of direct contact with a thermal environment. In ultrahigh vacuum, the dominant source of decoherence comes from the unavoidable photon recoil from the optical trap which sets an ultimate bound for the control of levitated systems. In this paper, we study the shot noise heating and the parametric feedback cooling of an optically trapped anisotropic nanoparticle in the laser shot noise dominant regime. The rotational trapping frequency and shot noise heating rate have a dependence on the shape of the trapped particle. For an ellipsoidal particle, the ratio of the axis lengths and the overall size controls the shot noise heating rate relative to the rotational frequency. For a near spherical nanoparticle, the effective heating rate for the rotational degrees of freedom is smaller than that for translation suggesting that the librational ground state may be easier to achieve than the vibrational ground state.

Bicontinuous structured liquids with sub-micrometre domains using nanoparticle surfactants

Science.gov (United States)

Huang, Caili; Forth, Joe; Wang, Weiyu; Hong, Kunlun; Smith, Gregory S.; Helms, Brett A.; Russell, Thomas P.

2017-11-01

Bicontinuous jammed emulsions (or bijels) are tortuous, interconnected structures of two immiscible liquids, kinetically trapped by colloidal particles that are irreversibly bound to the oil-water interface. A wealth of applications has been proposed for bijels in catalysis, energy storage and molecular encapsulation, but large domain sizes (on the order of 5 µm or larger) and difficulty in fabrication pose major barriers to their use. Here, we show that bijels with sub-micrometre domains can be formed via homogenization, rather than spinodal decomposition. We achieve this by using nanoparticle surfactants: polymers and nanoparticles of complementary functionality (for example, ion-pairing) that bind to one another at the oil-water interface. This allows the stabilization of the bijel far from the demixing point of the liquids, with interfacial tensions on the order of 20 mN m-1. Furthermore, our strategy is extremely versatile, as solvent, nanoparticle and ligand can all be varied.

Pulse laser-induced generation of cluster codes from metal nanoparticles for immunoassay applications

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Chia-Yin Chang

2017-05-01

Full Text Available In this work, we have developed an assay for the detection of proteins by functionalized nanomaterials coupled with laser-induced desorption/ionization mass spectrometry (LDI-MS by monitoring the generation of metal cluster ions. We achieved selective detection of three proteins [thrombin, vascular endothelial growth factor-A165 (VEGF-A165, and platelet-derived growth factor-BB (PDGF-BB] by modifying nanoparticles (NPs of three different metals (Au, Ag, and Pt with the corresponding aptamer or antibody in one assay. The Au, Ag, and Pt acted as metal bio-codes for the analysis of thrombin, VEGF-A165, and PDGF-BB, respectively, and a microporous cellulose acetate membrane (CAM served as a medium for an in situ separation of target protein-bound and -unbound NPs. The functionalized metal nanoparticles bound to their specific proteins were subjected to LDI-MS on the CAM. The functional nanoparticles/CAM system can function as a signal transducer and amplifier by transforming the protein concentration into an intense metal cluster ion signal during LDI-MS analysis. This system can selectively detect proteins at picomolar concentrations. Most importantly, the system has great potential for the detection of multiple proteins without any pre-concentration, separation, or purification process because LDI-MS coupled with CAM effectively removes all signals except for those from the metal cluster ions.

Preparation of porous polymer monoliths featuring enhanced surface coverage with gold nanoparticles

KAUST Repository

Lv, Yongqin

2012-10-01

A new approach to the preparation of porous polymer monoliths with enhanced coverage of pore surface with gold nanoparticles has been developed. First, a generic poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was reacted with cystamine followed by the cleavage of its disulfide bonds with tris(2-carboxylethyl)phosphine, which liberated the desired thiol groups. Dispersions of gold nanoparticles with sizes varying from 5 to 40. nm were then pumped through the functionalized monoliths. The materials were then analyzed using both energy dispersive X-ray spectroscopy and thermogravimetric analysis. We found that the quantity of attached gold was dependent on the size of nanoparticles, with the maximum attachment of more than 60. wt% being achieved with 40. nm nanoparticles. Scanning electron micrographs of the cross sections of all the monoliths revealed the formation of a non-aggregated, homogenous monolayer of nanoparticles. The surface of the bound gold was functionalized with 1-octanethiol and 1-octadecanethiol, and these monolithic columns were used successfully for the separations of proteins in reversed phase mode. The best separations were obtained using monoliths modified with 15, 20, and 30. nm nanoparticles since these sizes produced the most dense coverage of pore surface with gold. © 2012 Elsevier B.V.

Electron spin resonance spectroscopy for immunoassay using iron oxide nanoparticles as probe.

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Jiang, Jia; Tian, Sizhu; Wang, Kun; Wang, Yang; Zang, Shuang; Yu, Aimin; Zhang, Ziwei

2018-02-01

With the help of iron oxide nanoparticles, electron spin resonance spectroscopy (ESR) was applied to immunoassay. Iron oxide nanoparticles were used as the ESR probe in order to achieve an amplification of the signal resulting from the large amount of Fe 3+ ion enclosed in each nanoparticle. Rabbit IgG was used as antigen to test this method. Polyclonal antibody of rabbit IgG was used as antibody to detect the antigen. Iron oxide nanoparticle with a diameter of either 10 or 30 nm was labeled to the antibody, and Fe 3+ in the nanoparticle was probed for ESR signal. The sepharose beads were used as solid phase to which rabbit IgG was conjugated. The nanoparticle-labeled antibody was first added in the sample containing antigen, and the antigen-conjugated sepharose beads were then added into the sample. The nanoparticle-labeled antibody bound to the antigen on sepharose beads was separated from the sample by centrifugation and measured. We found that the detection ranges of the antigen obtained with nanoparticles of different sizes were different because the amount of antibody on nanoparticles of 10 nm was about one order of magnitude higher than that on nanoparticles of 30 nm. When 10 nm nanoparticle was used as probe, the upper limit of detection was 40.00 μg mL -1 , and the analytical sensitivity was 1.81 μg mL -1 . When 30 nm nanoparticle was used, the upper limit of detection was 3.00 μg mL -1 , and the sensitivity was 0.014 and 0.13 μg mL -1 depending on the ratio of nanoparticle to antibody. Graphical abstract Schematic diagram of procedure and ESR spectra.

Analysis of zinc oxide nanoparticles binding proteins in rat blood and brain homogenate

Directory of Open Access Journals (Sweden)

Shim KH

2014-12-01

Full Text Available Kyu Hwan Shim,1 John Hulme,1 Eun Ho Maeng,2 Meyoung-Kon Kim,3 Seong Soo A An1 1Department of Bionano Technology, Gachon Medical Research Institute, Gachon University, Sungnam-si, Gyeonggi-do, South Korea; 2Department of Analysis, KTR, Kimpo, Gyeonggi-do, South Korea; 3Department of Biochemistry and Molecular Biology, Korea University Medical School and College, Seoul, South Korea Abstract: Nanoparticles (NPs are currently used in chemical, cosmetic, pharmaceutical, and electronic products. Nevertheless, limited safety information is available for many NPs, especially in terms of their interactions with various binding proteins, leading to potential toxic effects. Zinc oxide (ZnO NPs are included in the formulation of new products, such as adhesives, batteries, ceramics, cosmetics, cement, glass, ointments, paints, pigments, and supplementary foods, resulting in increased human exposures to ZnO. Hence, we investigated the potential ZnO nanotoxic pathways by analyzing the adsorbed proteins, called protein corona, from blood and brain from four ZnO NPs, ZnOSM20(-, ZnOSM20(+, ZnOAE100(-, and ZnOAE100(+, in order to understand their potential mechanisms in vivo. Through this study, liquid chromatography–mass spectroscopy/mass spectroscopy technology was employed to identify all bound proteins. Totals of 52 and 58 plasma proteins were identified as being bound to ZnOSM20(- and ZnOSM20(+, respectively. For ZnOAE100(- and ZnOAE100(+, 58 and 44 proteins were bound, respectively. Similar numbers of proteins were adsorbed onto ZnO irrespective of size or surface charge of the nanoparticle. These proteins were further analyzed with ClueGO, a Cytoscape plugin, which provided gene ontology and the biological interaction processes of identified proteins. Interactions between diverse proteins and ZnO nanoparticles could result in an alteration of their functions, conformation, and clearance, eventually affecting many biological processes. Keywords: brain

Softening of phospholipid membranes by the adhesion of silica nanoparticles - as seen by neutron spin-echo (NSE)

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Hoffmann, Ingo; Michel, Raphael; Sharp, Melissa; Holderer, Olaf; Appavou, Marie-Sousai; Polzer, Frank; Farago, Bela; Gradzielski, Michael

2014-05-01

The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon

Photon virtual bound state

International Nuclear Information System (INIS)

Inoue, J.; Ohtaka, K.

2004-01-01

We study virtual bound states in photonics, which are a vectorial extension of electron virtual bound states. The condition for these states is derived. It is found that the Mie resonant state which satisfies the condition that the size parameter is less than the angular momentum should be interpreted as a photon virtual bound state. In order to confirm the validity of the concept, we compare the photonic density of states, the width of which represents the lifetime of the photon virtual bound states, with numerical results

Electron transfer dynamics of triphenylamine dyes bound to TiO2 nanoparticles from femtosecond stimulated Raman spectroscopy

KAUST Repository

Hoffman, David P.; Lee, Olivia P.; Millstone, Jill E.; Chen, Mark S.; Su, Timothy A.; Creelman, Mark; Frechet, Jean; Mathies, Richard A.

2013-01-01

Interfacial electron transfer between sensitizers and semiconducting nanoparticles is a crucial yet poorly understood process. To address this problem, we have used transient absorption (TA) and femtosecond stimulated Raman spectroscopy (FSRS

Directional rolling of positively charged nanoparticles along a flexibility gradient on long DNA molecules.

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Park, Suehyun; Joo, Heesun; Kim, Jun Soo

2018-01-31

Directing the motion of molecules/colloids in any specific direction is of great interest in many applications of chemistry, physics, and biological sciences, where regulated positioning or transportation of materials is highly desired. Using Brownian dynamics simulations of coarse-grained models of a long, double-stranded DNA molecule and positively charged nanoparticles, we observed that the motion of a single nanoparticle bound to and wrapped by the DNA molecule can be directed along a gradient of DNA local flexibility. The flexibility gradient is constructed along a 0.8 kilobase-pair DNA molecule such that local persistence length decreases gradually from 50 nm to 40 nm, mimicking a gradual change in sequence-dependent flexibility. Nanoparticles roll over a long DNA molecule from less flexible regions towards more flexible ones as a result of the decreasing energetic cost of DNA bending and wrapping. In addition, the rolling becomes slightly accelerated as the positive charge of nanoparticles decreases due to a lower free energy barrier of DNA detachment from charged nanoparticle for processive rolling. This study suggests that the variation in DNA local flexibility can be utilized in constructing and manipulating supramolecular assemblies of DNA molecules and nanoparticles in structural DNA nanotechnology.

Direct comparison of two albumin-based paclitaxel-loaded nanoparticle formulations: is the crosslinked version more advantageous?

Science.gov (United States)

Li, Chunlei; Li, Yanhui; Gao, Yuqing; Wei, Na; Zhao, Xi; Wang, Caixia; Li, Yongfeng; Xiu, Xian; Cui, Jingxia

2014-07-01

Nanoparticles using albumin as particle matrix have entered the mainstream of drug delivery. It was reported that non-crosslinked albumin nanoparticles were unstable in circulation and could deliver drugs into tumor through gp60/SPARC pathway; in contrast, the delivery of drugs with stable nanoparticles was dependent on enhanced permeability and retention effect. Thus, it is questionable which kind of nanoparticles was more advantageous. Two versions of albumin-bound paclitaxel nanoparticles were prepared. In vitro, the non-crosslinked particles could rapidly disintegrate and the crosslinked was stable. The pharmacokinetics of both formulations was different especially at early time and the non-crosslinked particles were cleared rapidly. After non-crosslinked particle treatment paclitaxel had a tendency to accumulate into heart and kidney and following therapy with the crosslinked particles, paclitaxel was liable to be delivered into lung, spleen and liver. The delivery efficiency of paclitaxel into tumor following the non-crosslinked particle treatment was greater than that of the crosslinked (palbumin nanoparticles. Copyright © 2014 Elsevier B.V. All rights reserved.

Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

International Nuclear Information System (INIS)

Wu, Pingxiao; Li, Shuzhen; Ju, Liting; Zhu, Nengwu; Wu, Jinhua; Li, Ping; Dang, Zhi

2012-01-01

Highlights: ► Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. ► The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. ► XPS and XANES provided some direct information about the reduction mechanisms. ► The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe 0 , and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe 0 was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

An Effective Delivery System of Sitagliptin Using Optimized Mucoadhesive Nanoparticles

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Afzal Haq Asif

2018-05-01

Full Text Available Sitagliptin (MK-0431, is a potent oral hypoglycemic drug that is used for treating type 2 diabetes mellitus. However, the short half-life of sitagliptin requires patients to take a high dose of 50 mg twice per day, and the fraction of sitagliptin reversibly bound to plasma proteins is as low as 38%. In addition, it was reported that approximately 79% of sitagliptin is excreted unchanged in the urine for elimination without metabolism. Thus, a better delivery system is needed to improve the benefits of sitagliptin in patients. The drug content and percentage yield were found to be 73 ± 2% and 92 ± 2%, respectively. The optimized sitagliptin nanoparticle sizes were between 350–950 nm, and the surfaces were smooth and nearly spherical in shape. In addition, the optimized sitagliptin nanoparticles have an indicated excellent bioadhesion property of (6.1 ± 0.5 h. The swelling of the nanoparticles is 168 ± 15%. The pattern of sitagliptin release from the mucoadhesive nanoparticles follows the Korsmeyer-Peppas model. More importantly, the extended sitagliptin retention time, of up to 12 h in the gastrointestinal tract, suggests that the optimized mucoadhesive nanoparticle formulation is more efficient, and has a greater potential to be used for oral delivery compared to the conventional sitagliptin administration in the drug solution. This is the first developed delivery system using the optimized mucoadhesive nanoparticles to enhance the effectiveness of sitagliptin.

Self-oriented nanoparticles for site-selective immunoglobulin G recognition via epitope imprinting approach.

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Çorman, Mehmet Emin; Armutcu, Canan; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

2014-11-01

Molecular imprinting is a polymerization technique that provides synthetic analogs for template molecules. Molecularly imprinted polymers (MIPs) have gained much attention due to their unique properties such as selectivity and specificity for target molecules. In this study, we focused on the development of polymeric materials with molecular recognition ability, so molecular imprinting was combined with miniemulsion polymerization to synthesize self-orienting nanoparticles through the use of an epitope imprinting approach. Thus, L-lysine imprinted nanoparticles (LMIP) were synthesized via miniemulsion polymerization technique. Immunoglobulin G (IgG) was then bound to the cavities that specifically formed for L-lysine molecules that are typically found at the C-terminus of the Fc region of antibody molecules. The resulting nanoparticles makes it possible to minimize the nonspecific interaction between monomer and template molecules. In addition, the orientation of the entire IgG molecule was controlled, and random imprinting of the IgG was prevented. The optimum conditions were determined for IgG recognition using the imprinted nanoparticles. The selectivity of the nanoparticles against IgG molecules was also evaluated using albumin and hemoglobin as competitor molecules. In order to show the self-orientation capability of imprinted nanoparticles, human serum albumin (HSA) adsorption onto both the plain nanoparticles and immobilized nanoparticles by anti-human serum albumin antibody (anti-HSA antibody) was also carried out. Due to anti-HSA antibody immobilization on the imprinted nanoparticles, the adsorption capability of nanoparticles against HSA molecules vigorously enhanced. It is proved that the oriented immobilization of antibodies was appropriately succeeded. Copyright © 2014 Elsevier B.V. All rights reserved.

BSA nanoparticle loaded atorvastatin calcium--a new facet for an old drug.

Science.gov (United States)

Sripriyalakshmi, S; Anjali, C H; George, Priya Doss C; Rajith, B; Ravindran, Aswathy

2014-01-01

Currently, the discovery of effective chemotherapeutic agents poses a major challenge to the field of cancer biology. The present study focuses on enhancing the therapeutic and anti cancer properties of atorvastatin calcium loaded BSA (ATV-BSA) nanoparticles in vitro. BSA-ATV nanoparticles were prepared using desolvation technique. The process parameters were optimized based on the amount of desolvating agent, stabilization conditions as well as the concentration of the cross linker. The anti cancer properties of the protein coated ATV nanoparticles were tested on MiaPaCa-2 cell lines. In vitro release behavior of the drug from the carrier suggests that about 85% of the drug gets released after 72 hrs. Our studies show that ATV-BSA nanoparticles showed specific targeting and enhanced cytotoxicity to MiaPaCa-2 cells when compared to the bare ATV. We hereby propose that the possible mechanism of cellular uptake of albumin bound ATV could be through caveolin mediated endocytosis. Hence our studies open up new facet for an existing cholesterol drug as a potent anti-cancer agent.

Mechanical control of the plasmon coupling with Au nanoparticle arrays fixed on the elastomeric film via chemical bond

Science.gov (United States)

Bedogni, Elena; Kaneko, Satoshi; Fujii, Shintaro; Kiguchi, Manabu

2017-03-01

We have fabricated Au nanoparticle arrays on the flexible poly(dimethylsiloxane) (PDMS) film. The nanoparticles were bound to the film via a covalent bond by a ligand exchange reaction. Thanks to the strong chemical bonding, highly stable and uniformly dispersed Au nanoparticle arrays were fixed on the PDMS film. The Au nanoparticle arrays were characterized by the UV-vis, scanning electron microscope (SEM) and surface enhanced Raman scattering (SERS). The UV-vis and SEM measurements showed the uniformity of the surface-dispersed Au nanoparticles, and SERS measurement confirmed the chemistry of the PDMS film. Reflecting the high stability and the uniformity of the Au nanoparticle arrays, the plasmon wavelength of the Au nanoparticles reversely changed with modulation of the interparticle distance, which was induced by the stretching of the PDMS film. The plasmon wavelength linearly decreased from 664 to 591 nm by stretching of 60%. The plasmon wavelength shift can be explained by the change in the strength of the plasmon coupling which is mechanically controlled by the mechanical strain.

Weekly nanoparticle albumin bound-paclitaxel in combination with cisplatin versus weekly solvent-based paclitaxel plus cisplatin as first-line therapy in Chinese patients with advanced esophageal squamous cell carcinoma

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Wang HY

2016-09-01

Full Text Available Hai-ying Wang, Zhi-hua Yao, Hong Tang, Yan Zhao, Xiao-san Zhang, Shu-na Yao, Shu-jun Yang, Yan-yan Liu Department of Internal Medicine, Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou, Henan, People’s Republic of China Objective: More effective regimens for advanced esophageal squamous cell carcinoma (ESCC are urgently needed. Therefore, a retrospective study concerning the efficacy and safety of nanoparticle albumin-bound paclitaxel plus cisplatin (nab-TP versus solvent-based paclitaxel plus cisplatin (sb-TP as a first-line therapy was conducted in Chinese patients with advanced ESCC.Methods: From June 2009 to June 2015, 32 patients were treated with nab-paclitaxel (125 mg/m2 on the first and eighth days (30 minutes infusion and cisplatin (75 mg/m2 on the second day every 21 days (nab-TP arm. Also, 43 patients were treated with solvent-based paclitaxel (80 mg/m2 intravenously on the first and eighth days and the same dose of cisplatin (sb-TP arm. The two groups were compared in terms of objective response rate (ORR, disease control rate, progression-free survival (PFS, overall survival (OS, and safety profile. OS and PFS were estimated using Kaplan–Meier methods to determine associations between chemotherapy regimens and survival outcomes.Results: Nab-TP demonstrated a higher ORR (50% vs 30%; P=0.082 and disease control rate (81% vs 65%; P=0.124 than sb-TP. Median OS was similar for nab-TP and sb-TP (12.5 vs 10.7 months; P=0.269. However, nab-TP resulted in a longer median PFS (6.1 months [95% confidence interval: 5.3–6.9] than sb-TP (5.0 months [95% confidence interval: 4.4–5.6] (P=0.029. The most common adverse events included anemia, leukopenia, neutropenia, febrile neutropenia, and thrombocytopenia in both the groups and no statistically significant differences were observed between the groups. With statistically significant differences, significantly less grade ≥3 peripheral neuropathy

Detection of dopamine in dopaminergic cell using nanoparticles-based barcode DNA analysis.

Science.gov (United States)

An, Jeung Hee; Kim, Tae-Hyung; Oh, Byung-Keun; Choi, Jeong Woo

2012-01-01

Nanotechnology-based bio-barcode-amplification analysis may be an innovative approach to dopamine detection. In this study, we evaluated the efficacy of this bio-barcode DNA method in detecting dopamine from dopaminergic cells. Herein, a combination DNA barcode and bead-based immunoassay for neurotransmitter detection with PCR-like sensitivity is described. This method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA, and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated in order to remove the conjugated barcode DNA. The DNA barcodes were then identified via PCR analysis. The dopamine concentration in dopaminergic cells can be readily and rapidly detected via the bio-barcode assay method. The bio-barcode assay method is, therefore, a rapid and high-throughput screening tool for the detection of neurotransmitters such as dopamine.

Curvature bound from gravitational catalysis

Science.gov (United States)

Gies, Holger; Martini, Riccardo

2018-04-01

We determine bounds on the curvature of local patches of spacetime from the requirement of intact long-range chiral symmetry. The bounds arise from a scale-dependent analysis of gravitational catalysis and its influence on the effective potential for the chiral order parameter, as induced by fermionic fluctuations on a curved spacetime with local hyperbolic properties. The bound is expressed in terms of the local curvature scalar measured in units of a gauge-invariant coarse-graining scale. We argue that any effective field theory of quantum gravity obeying this curvature bound is safe from chiral symmetry breaking through gravitational catalysis and thus compatible with the simultaneous existence of chiral fermions in the low-energy spectrum. With increasing number of dimensions, the curvature bound in terms of the hyperbolic scale parameter becomes stronger. Applying the curvature bound to the asymptotic safety scenario for quantum gravity in four spacetime dimensions translates into bounds on the matter content of particle physics models.

Surface-Bound Ligands Modulate Chemoselectivity and Activity of a Bimetallic Nanoparticle Catalyst

KAUST Repository

Vu, Khanh B.

2015-04-03

"Naked" metal nanoparticles (NPs) are thermodynamically and kinetically unstable in solution. Ligands, surfactants, or polymers, which adsorb at a particle\\'s surface, can be used to stabilize NPs; however, such a mode of stabilization is undesirable for catalytic applications because the adsorbates block the surface active sites. The catalytic activity and the stability of NPs are usually inversely correlated. Here, we describe an example of a bimetallic (PtFe) NP catalyst stabilized by carboxylate surface ligands that bind preferentially to one of the metals (Fe). NPs stabilized by fluorous ligands were found to be remarkably competent in catalyzing the hydrogenation of cinnamaldehyde; NPs stabilized by hydrocarbon ligands were significantly less active. The chain length of the fluorous ligands played a key role in determining the chemoselectivity of the FePt NP catalysts. (Chemical Presented). © 2015 American Chemical Society.

Deeply bound pionic atom

International Nuclear Information System (INIS)

Toki, Hiroshi; Yamazaki, Toshimitsu

1989-01-01

The standard method of pionic atom formation does not produce deeply bound pionic atoms. A study is made on the properties of deeply bound pionic atom states by using the standard pion-nucleus optical potential. Another study is made to estimate the cross sections of the formation of ls pionic atom states by various methods. The pion-nucleus optical potential is determined by weakly bound pionic atom states and pion nucleus scattering. Although this potential may not be valid for deeply bound pionic atoms, it should provide some hint on binding energies and level widths of deeply bound states. The width of the ls state comes out to be 0.3 MeV and is well separated from the rest. The charge dependence of the ls state is investigated. The binding energies and the widths increase linearly with Z azbove a Z of 30. The report then discusses various methods to populate deeply bound pionic atoms. In particular, 'pion exchange' reactions are proposed. (n, pπ) reaction is discussed first. The cross section is calculated by assuming the in- and out-going nucleons on-shell and the produced pion in (n1) pionic atom states. Then, (n, dπ - ) cross sections are estimated. (p, 2 Heπ - ) reaction would have cross sections similar to the cross section of (n, dπ - ) reaction. In conclusion, it seems best to do (n, p) experiment on heavy nuclei for deeply bound pionic atom. (Nogami, K.)

Feasibility of MR imaging in evaluating breast cancer lymphangiogenesis using Polyethylene glycol-GoldMag nanoparticles

International Nuclear Information System (INIS)

Yang, H.; Zou, L.G.; Zhang, S.; Gong, M.F.; Zhang, D.; Qi, Y.Y.; Zhou, S.W.; Diao, X.W.

2013-01-01

Aim: To investigate the feasibility of evaluating tumour lymphangiogenesis using magnetic resonance imaging (MRI) in vivo. Materials and methods: Water-soluble polyethylene glycol (PEG)-GoldMag nanoparticles were obtained by combining GoldMag with PEG. The PEG-GoldMag nanoparticles were bound to anti-podoplanin antibody (PodAb) to construct PEG-GoldMag-pod molecular probes targeting lymphatic endothelial cells (LECs). The characteristics of the PEG-GoldMag-pod nanoparticles were tested. Using these nanoparticles, tumour lymphangiogenesis was evaluated using MRI in vitro and in vivo. Results: The average size of PEG-GoldMag nanoparticles was about 66.8 nm, and the nanoparticles were stably dispersed in the liquid phase for at least 15 days. After incubation for 24 h at different iron concentrations ranging from 5–45 μg/ml, the LECs were labelled with PEG-GoldMag-pod nanoparticles, in particular the breast cancer LECs. Dose-dependence was observed in the labelling efficiencies and MRI images of the labelled cells. In vitro, the labelling efficiencies and MRI images showed that the nanoparticles could detect podoplanin expression in LECs. In induced rat models of breast cancer, PEG-GoldMag-pod nanoparticles combined with lymphatic vessels were significantly detectable at MRI 60 min after nanoparticle administration, the signal intensity was negatively correlated with the lymphatic vessel density of breast cancer (r = −0.864, P = 0.000). Conclusions: The present study proves the feasibility of evaluating tumour lymphangiogenesis with MRI in vivo

Doxorubicin loaded PVA coated iron oxide nanoparticles for targeted drug delivery

International Nuclear Information System (INIS)

Kayal, S.; Ramanujan, R.V.

2010-01-01

Magnetic drug targeting is a drug delivery system that can be used in locoregional cancer treatment. Coated magnetic particles, called carriers, are very useful for delivering chemotherapeutic drugs. Magnetic carriers were synthesized by coprecipitation of iron oxide followed by coating with polyvinyl alcohol (PVA). Characterization was carried out using X-ray diffraction, TEM, TGA, FTIR and VSM techniques. The magnetic core of the carriers was magnetite (Fe 3 O 4 ), with average size of 10 nm. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. The amount of PVA bound to the iron oxide nanoparticles were estimated by thermogravimetric analysis (TGA) and the attachment of PVA to the iron oxide nanoparticles was confirmed by FTIR analysis. Doxorubicin (DOX) drug loading and release profiles of PVA coated iron oxide nanoparticles showed that up to 45% of adsorbed drug was released in 80 h, the drug release followed the Fickian diffusion-controlled process. The binding of DOX to the PVA was confirmed by FTIR analysis. The present findings show that DOX loaded PVA coated iron oxide nanoparticles are promising for magnetically targeted drug delivery.

One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

Energy Technology Data Exchange (ETDEWEB)

Sakalak, Huseyin [Selcuk University, Metallurgy and Materials Engineering (Turkey); Ulasan, Mehmet; Yavuz, Emine [Selcuk University, Advanced Technology Research and Application Center (Turkey); Camli, Sevket Tolga, E-mail: tolgacamli@gmail.com [Biyotez Machinery Chemistry R& D Co. Ltd. (Turkey); Yavuz, Mustafa Selman, E-mail: selmanyavuz@selcuk.edu.tr [Selcuk University, Metallurgy and Materials Engineering (Turkey)

2014-12-15

Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV–Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells.

One-pot synthesis of biocompatible boronic acid-functionalized poly(methyl methacrylate) nanoparticles at sub-100 nm scale for glucose sensing

International Nuclear Information System (INIS)

Sakalak, Huseyin; Ulasan, Mehmet; Yavuz, Emine; Camli, Sevket Tolga; Yavuz, Mustafa Selman

2014-01-01

Poly(methyl methacrylate) nanoparticles containing 4-vinylphenyl boronic acid were synthesized in one pot by surfactant-free emulsion polymerization. The nanoparticles were characterized by scanning electron microscopy and dynamic light scattering. Boron content in the nanoparticles was confirmed by electron-dispersive X-ray spectroscopy. In polymerization process, several co-monomer ratios were studied in order to obtain optimum nanoparticle size. Average hydrodynamic diameter and polydispersity index of nanoparticles versus variation of acetone percentage in the solvent mixture and total monomer concentration were investigated. The effect of boronic acid concentration in the monomer mixture on nanoparticle size and size distribution was also reported. Without further functionalization to the nanoparticles, the catechol dye, alizarin red S, was bound to boronic acid-containing nanoparticles. These nanoparticles behave as a nanosensor by which glucose or fructose can be easily detected. Dye-containing nanoparticles were undertaken displacement reaction by glucose or fructose. The glucose or fructose content was also monitored by UV–Visible spectrophotometer. Furthermore, cytotoxicity studies of boronic acid-carrying poly(methyl methacrylate) nanoparticles were carried out in 3T3 cells, which showed no toxicity effect on the cells

In vitro and in vivo investigations of targeted chemotherapy with magnetic nanoparticles

International Nuclear Information System (INIS)

Alexiou, Christoph; Jurgons, Roland; Schmid, Roswitha; Hilpert, Andrea; Bergemann, Christian; Parak, Fritz; Iro, Heinrich

2005-01-01

Magnetic drug targeting is a local drug delivery system. Electromicroscopic pictures document the ferrofluid enrichment in the intracellular space in vitro. In vivo experiments were performed in VX2 tumor-bearing rabbits using magnetic nanoparticles bound to mitoxantrone. High-pressure liquid chromatography (HPLC) analyses after magnetic drug targeting showed an increasing concentration of the chemotherapeutic agent in the tumor region compared to regular systemic chemotherapy

Bounding species distribution models

Directory of Open Access Journals (Sweden)

Thomas J. STOHLGREN, Catherine S. JARNEVICH, Wayne E. ESAIAS,Jeffrey T. MORISETTE

2011-10-01

Full Text Available Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for “clamping” model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART and maximum entropy (Maxent models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5: 642–647, 2011].

Bounding Species Distribution Models

Science.gov (United States)

Stohlgren, Thomas J.; Jarnevich, Cahterine S.; Morisette, Jeffrey T.; Esaias, Wayne E.

2011-01-01

Species distribution models are increasing in popularity for mapping suitable habitat for species of management concern. Many investigators now recognize that extrapolations of these models with geographic information systems (GIS) might be sensitive to the environmental bounds of the data used in their development, yet there is no recommended best practice for "clamping" model extrapolations. We relied on two commonly used modeling approaches: classification and regression tree (CART) and maximum entropy (Maxent) models, and we tested a simple alteration of the model extrapolations, bounding extrapolations to the maximum and minimum values of primary environmental predictors, to provide a more realistic map of suitable habitat of hybridized Africanized honey bees in the southwestern United States. Findings suggest that multiple models of bounding, and the most conservative bounding of species distribution models, like those presented here, should probably replace the unbounded or loosely bounded techniques currently used [Current Zoology 57 (5): 642-647, 2011].

Investigation of active biomolecules involved in the nucleation and growth of gold nanoparticles by Artocarpus heterophyllus Lam leaf extract

Energy Technology Data Exchange (ETDEWEB)

Jiang Xinde; Sun Daohua, E-mail: sdaohua@xmu.edu.cn; Zhang Genlei; He Ning; Liu Hongyu; Huang Jiale; Odoom-Wubah, Tareque; Li Qingbiao, E-mail: kelqb@xmu.edu.cn [Xiamen University, Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Fujian Provincial Key Laboratory of Chemical Biology (China)

2013-06-15

The effects of different biomolecules in Artocarpus heterophyllus Lam leaf extract on the morphology of obtained gold nanoparticles were investigated in this study. The results indicated that reducing sugars, flavones, and polyphenols consisting of about 79.8 % dry weight of the leaf extract were mainly involved in providing the dual function of reduction and the size/shape control during the biosynthesis. The gold nanoparticles present included 64 {+-} 10 nm nanospheres, 131 {+-} 18 nm nanoflowers, and 347 {+-} 136 nm (edge length) nanoplates and they were synthesized using the main content of reducing sugars, flavones, and polyphenols, respectively, after they were desorbed by the AB-8 macroporous adsorption resin column. Particularly, flower-like and triangular/hexagonal gold nanoparticles with a yield more than 80 % were obtained. Possible shape-directed agents for the nucleation and growth were characterized by FTIR, it can be seen that ketones were bound on the surface of the spherical and flower-like GNPs, while both the ketones and carbonyls bound on the Au {l_brace}111{r_brace} plane this may have favored the formation of the twin defects, which are very essential for nanoplates' formation.

Investigation of active biomolecules involved in the nucleation and growth of gold nanoparticles by Artocarpus heterophyllus Lam leaf extract

International Nuclear Information System (INIS)

Jiang Xinde; Sun Daohua; Zhang Genlei; He Ning; Liu Hongyu; Huang Jiale; Odoom-Wubah, Tareque; Li Qingbiao

2013-01-01

The effects of different biomolecules in Artocarpus heterophyllus Lam leaf extract on the morphology of obtained gold nanoparticles were investigated in this study. The results indicated that reducing sugars, flavones, and polyphenols consisting of about 79.8 % dry weight of the leaf extract were mainly involved in providing the dual function of reduction and the size/shape control during the biosynthesis. The gold nanoparticles present included 64 ± 10 nm nanospheres, 131 ± 18 nm nanoflowers, and 347 ± 136 nm (edge length) nanoplates and they were synthesized using the main content of reducing sugars, flavones, and polyphenols, respectively, after they were desorbed by the AB-8 macroporous adsorption resin column. Particularly, flower-like and triangular/hexagonal gold nanoparticles with a yield more than 80 % were obtained. Possible shape-directed agents for the nucleation and growth were characterized by FTIR, it can be seen that ketones were bound on the surface of the spherical and flower-like GNPs, while both the ketones and carbonyls bound on the Au {111} plane this may have favored the formation of the twin defects, which are very essential for nanoplates’ formation.

Investigation of active biomolecules involved in the nucleation and growth of gold nanoparticles by Artocarpus heterophyllus Lam leaf extract

Science.gov (United States)

Jiang, Xinde; Sun, Daohua; Zhang, Genlei; He, Ning; Liu, Hongyu; Huang, Jiale; Odoom-Wubah, Tareque; Li, Qingbiao

2013-06-01

The effects of different biomolecules in Artocarpus heterophyllus Lam leaf extract on the morphology of obtained gold nanoparticles were investigated in this study. The results indicated that reducing sugars, flavones, and polyphenols consisting of about 79.8 % dry weight of the leaf extract were mainly involved in providing the dual function of reduction and the size/shape control during the biosynthesis. The gold nanoparticles present included 64 ± 10 nm nanospheres, 131 ± 18 nm nanoflowers, and 347 ± 136 nm (edge length) nanoplates and they were synthesized using the main content of reducing sugars, flavones, and polyphenols, respectively, after they were desorbed by the AB-8 macroporous adsorption resin column. Particularly, flower-like and triangular/hexagonal gold nanoparticles with a yield more than 80 % were obtained. Possible shape-directed agents for the nucleation and growth were characterized by FTIR, it can be seen that ketones were bound on the surface of the spherical and flower-like GNPs, while both the ketones and carbonyls bound on the Au {111} plane this may have favored the formation of the twin defects, which are very essential for nanoplates' formation.

Mechanism of the reduction of hexavalent chromium by organo-montmorillonite supported iron nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wu, Pingxiao, E-mail: pppxwu@scut.edu.cn [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Li, Shuzhen [School of Chemical and Environmental Engineering, Wuyi University, Jiangmen, Guangdong Province 529020 (China); Ju, Liting [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Zhu, Nengwu [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China); Wu, Jinhua; Li, Ping [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); Dang, Zhi [College of Environmental Science and Engineering, South China University of Technology, Guangzhou 510006 (China); The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou 510006 (China); The Key Laboratory of Environmental Protection and Eco-Remediation of Guangdong Regular Higher Education Institutions (China)

2012-06-15

Highlights: Black-Right-Pointing-Pointer Organo-montmorillonite supported iron nanoparticles were found to be more efficient in the removal of Cr(VI) than unsupported iron nanoparticles. Black-Right-Pointing-Pointer The iron nanoparticles were accommodated by the sectional structure of the clay minerals which were helpful to protect the nanoparticles from aggregating. Black-Right-Pointing-Pointer XPS and XANES provided some direct information about the reduction mechanisms. Black-Right-Pointing-Pointer The structure of the supported iron nanoparticles was stable in the reaction with Cr(VI). - Abstract: Iron nanoparticles exhibit greater reactivity than micro-sized Fe{sup 0}, and they impart advantages for groundwater remediation. In this paper, supported iron nanoparticles were synthesized to further enhance the speed and efficiency of remediation. Natural montmorillonite and organo-montmorillonite were chosen as supporting materials. The capacity of supported iron nanoparticles was evaluated, compared to unsupported iron nanoparticles, for the reduction of aqueous Cr(VI). The reduction of Cr(VI) was much greater with organo-montmorillonite supported iron nanoparticles and fitted the pseudo-second order equation better. With a dose at 0.47 g/L, a total removal capacity of 106 mg Cr/g Fe{sup 0} was obtained. Other factors that affect the efficiency of Cr(VI) removal, such as pH values, the initial Cr(VI) concentration and storage time of nanoparticles were investigated. X-ray photoelectron spectrometry (XPS) and X-ray absorption near edge structure (XANES) were used to figure out the mechanism of the removal of Cr(VI). XPS indicated that the Cr(VI) bound to the particle surface was completely reduced to Cr(III) under a range of conditions. XANES confirmed that the Cr(VI) reacted with iron nanoparticles was completely reduced to Cr(III).

Albumin nanoparticles with synergistic antitumor efficacy against metastatic lung cancers.

Science.gov (United States)

Kim, Bomi; Seo, Bohyung; Park, Sanghyun; Lee, Changkyu; Kim, Jong Oh; Oh, Kyung Taek; Lee, Eun Seong; Choi, Han-Gon; Youn, Yu Seok

2017-10-01

Albumin nanoparticles are well-known as effective drug carriers used to deliver hydrophobic chemotherapeutic agents. Albumin nanoparticles encapsulating curcumin and doxorubicin were fabricated using slightly modified nanoparticle albumin-bound (nab™) technology, and the synergistic effects of these two drugs were examined. Albumin nanoparticles encapsulating curcumin, doxorubicin, and both curcumin and doxorubicin were prepared using a high pressure homogenizer. The sizes of albumin nanoparticles were ∼130nm, which was considered to be suitable for the EPR (enhanced permeability and retention) effect. Albumin nanoparticles gradually released drugs over a period of 24h without burst effect. To confirm the synergistic effect of two drugs, in vitro cytotoxicity assay was performed using B16F10 melanoma cells. The cytotoxic effect on B16F10 melanoma cells was highest when co-treated with both curcumin and doxorubicin compared to single treatment of either curcumin and doxorubicin. The combined index calculated by medium-effect equation was 0.6069, indicating a synergistic effect. Results of confocal laser scanning microscopy and fluorescence-activated cell sorting corresponded to results from an in vitro cytotoxicity assay, indicating synergistic cytotoxicity induced by both drugs. A C57BL/6 mouse model induced by B16F10 lung metastasis was used to study in vivo therapeutic effects. When curcumin and doxorubicin were simultaneously treated, the metastatic melanoma mass in the lungs macroscopically decreased compared to curcumin or doxorubicin alone. Albumin nanoparticles encapsulating two anticancer drugs were shown to have an effective therapeutic result and would be an excellent way to treat resistant lung cancers. Copyright © 2017 Elsevier B.V. All rights reserved.

Polymeric gel nanoparticle pH sensors for intracellular measurements

OpenAIRE

Almdal, Kristoffer; Andresen, Thomas Lars; Benjaminsen, Rikke Vicki; Christensen, Nynne Meyn; Henriksen, Jonas Rosager; Sun, Honghao

2011-01-01

Precise measurements of pH in cells and intracellular compartments are of importance to both the fundamental understanding of metabolism and to the development of drugs that are released from the endosomes-lysome pathway. We have developed polymer gel nanoparticles as carriers of covalently bound fluorophores for ratiometric measurements of pH. One pH insensitive fluorophore serves as a reference while one or more pH sensitive fluorophores serve to give the desired pH dependence of the output...

Nano-particles for therapeutical purposes: an innovative approach for the radiotherapy of cancer

International Nuclear Information System (INIS)

Borghi, E.; Said, P.; Pottier, A.; Levy, L.

2010-01-01

Nano-technology can be used to manage and assemble substances in unprecedented ways in the history of products for human health. Underlying this revolution are the possibilities for using new therapeutic processes and separating a drug's various functions (distribution, effects, etc.). This is not possible with classical drugs. Nano-medicine has made it possible to develop new approaches to treating cancer, by using nano-particles with physical effects at the scale of the malignant cell. Hard metallic oxide nano-particles have been designed so that they can play a therapeutic role when activated by x-rays. The x-rays irradiation will free electrons from the metallic oxide, these electrons will lose energy through collisions with water molecules and will create free radicals in the cells. These free radicals are very reactive and will damage the covalent bounds of the molecules located around the nano-particles. Clinical tests on man are expected to begin very soon. These 'x-ray-activable' nano-particles might set off a revolution in the practice of radiotherapy for destroying or controlling malignant tumors

Polyelectrolyte Complex Nanoparticles of Poly(ethyleneimine and Poly(acrylic acid: Preparation and Applications

Directory of Open Access Journals (Sweden)

Martin Müller

2011-04-01

Full Text Available In this contribution we outline polyelectrolyte (PEL complex (PEC nanoparticles, prepared by mixing solutions of the low cost PEL components poly(ethyleneimine (PEI and poly(acrylic acid (PAC. It was found, that the size and internal structure of PEI/PAC particles can be regulated by process, media and structural parameters. Especially, mixing order, mixing ratio, PEL concentration, pH and molecular weight, were found to be sensible parameters to regulate the size (diameter of spherical PEI/PAC nanoparticles, in the range between 80–1,000 nm, in a defined way. Finally, applications of dispersed PEI/PAC particles as additives for the paper making process, as well as for drug delivery, are outlined. PEI/PAC nanoparticles mixed directly on model cellulose film showed a higher adsorption level applying the mixing order 1. PAC 2. PEI compared to 1. PEI 2. PAC. Surface bound PEI/PAC nanoparticles were found to release a model drug compound and to stay immobilized due to the contact with the aqueous release medium.

Evaluation of In-Situ Magnetic Signals from Iron Oxide Nanoparticle-Labeled PC12 Cells by Atomic Force Microscopy.

Science.gov (United States)

Wang, Lijun; Min, Yue; Wang, Zhigang; Riggio, Cristina; Calatayud, M Pilar; Pinkernelle, Josephine; Raffa, Vittoria; Goya, Gerardo F; Keilhoff, Gerburg; Cuschieri, Alfred

2015-03-01

The magnetic signals from magnetite nanoparticle-labeled PC12 cells were assessed by magnetic force microscopy by deploying a localized external magnetic field to magnetize the nanoparticles and the magnetic tip simultaneously so that the interaction between the tip and PC12 cell-associated Fe3O4 nanoparticles could be detected at lift heights (the distance between the tip and the sample) larger than 100 nm. The use of large lift heights during the raster scanning of the probe eliminates the non-magnetic interference from the complex and rugged cell surface and yet maintains the sufficient sensitivity for magnetic detection. The magnetic signals of the cell-bound nanoparticles were semi-quantified by analyzing cell surface roughness upon three-dimensional reconstruction generated by the phase shift of the cantilever oscillation. The obtained data can be used for the evaluation of the overall cellular magnetization as well as the maximum magnetic forces from magnetic nanoparticle-labeled cells which is crucial for the biomedical application of these nanomaterials.

Labeling schemes for bounded degree graphs

DEFF Research Database (Denmark)

Adjiashvili, David; Rotbart, Noy Galil

2014-01-01

We investigate adjacency labeling schemes for graphs of bounded degree Δ = O(1). In particular, we present an optimal (up to an additive constant) log n + O(1) adjacency labeling scheme for bounded degree trees. The latter scheme is derived from a labeling scheme for bounded degree outerplanar...... graphs. Our results complement a similar bound recently obtained for bounded depth trees [Fraigniaud and Korman, SODA 2010], and may provide new insights for closing the long standing gap for adjacency in trees [Alstrup and Rauhe, FOCS 2002]. We also provide improved labeling schemes for bounded degree...

Highly stable, protein capped gold nanoparticles as effective drug delivery vehicles for amino-glycosidic antibiotics

International Nuclear Information System (INIS)

Rastogi, Lori; Kora, Aruna Jyothi; Arunachalam, J.

2012-01-01

A method for the production of highly stable gold nanoparticles (Au NP) was optimized using sodium borohydride as reducing agent and bovine serum albumin as capping agent. The synthesized nanoparticles were characterized using UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction (XRD) and dynamic light scattering techniques. The formation of gold nanoparticles was confirmed from the appearance of pink colour and an absorption maximum at 532 nm. These protein capped nanoparticles exhibited excellent stability towards pH modification and electrolyte addition. The produced nanoparticles were found to be spherical in shape, nearly monodispersed and with an average particle size of 7.8 ± 1.7 nm. Crystalline nature of the nanoparticles in face centered cubic structure is confirmed from the selected‐area electron diffraction and XRD patterns. The nanoparticles were functionalized with various amino-glycosidic antibiotics for utilizing them as drug delivery vehicles. Using Fourier transform infrared spectroscopy, the possible functional groups of antibiotics bound to the nanoparticle surface have been examined. These drug loaded nanoparticle solutions were tested for their antibacterial activity against Gram-negative and Gram-positive bacterial strains, by well diffusion assay. The antibiotic conjugated Au NP exhibited enhanced antibacterial activity, compared to pure antibiotic at the same concentration. Being protein capped and highly stable, these gold nanoparticles can act as effective carriers for drugs and might have considerable applications in the field of infection prevention and therapeutics. - Highlights: ► Method for NaBH 4 reduced and BSA capped gold nanoparticle was standardized. ► Nanoparticles were spherical and nearly monodispersed with a size of 7.8 nm. ► Nanoparticles are extremely stable towards pH modification and electrolyte addition. ► Antibiotic conjugated nanoparticles exhibited enhanced antibacterial activity

Targeted drug delivery with polymers and magnetic nanoparticles: covalent and noncovalent approaches, release control, and clinical studies

Czech Academy of Sciences Publication Activity Database

Ulbrich, Karel; Holá, K.; Šubr, Vladimír; Bakandritsos, A.; Tuček, J.; Zbořil, R.

2016-01-01

Roč. 116, č. 9 (2016), s. 5338-5431 ISSN 0009-2665 R&D Projects: GA ČR(CZ) GAP301/12/1254 Institutional support: RVO:61389013 Keywords : iron-oxide nanoparticles * cell lung-cancer * copolymer-bound doxorubicin Subject RIV: CD - Macromolecular Chemistry Impact factor: 47.928, year: 2016

Glyconanobiotics: Novel carbohydrated nanoparticle antibiotics for MRSA and Bacillus anthracis

OpenAIRE

Abeylath, Sampath C.; Turos, Edward; Dickey, Sonja; Limb, Daniel V.

2007-01-01

This report describes the synthesis and evaluation of glycosylated polyacrylate nanoparticles that have covalently-bound antibiotics within their framework. The requisite glycosylated drug monomers were prepared from one of three known antibiotics, an N-sec-butylthio β-lactam, ciprofloxacin, and a penicillin, by acylation with 3-O-acryloyl-1,2-O-isopropylidene-5,6 bis((chlorosuccinyl)oxy)-D-glucofuranose (7) or 6-O-acetyl-3-O-acryloyl-1,2-O-isopropylidene-5-(chlorosuccinyl)oxy-α-D-glucofurano...

Tunneling Mode of Scanning Electrochemical Microscopy: Probing Electrochemical Processes at Single Nanoparticles.

Science.gov (United States)

Sun, Tong; Wang, Dengchao; Mirkin, Michael V

2018-06-18

Electrochemical experiments at individual nanoparticles (NPs) can provide new insights into their structure-activity relationships. By using small nanoelectrodes as tips in a scanning electrochemical microscope (SECM), we recently imaged individual surface-bound 10-50 nm metal NPs. Herein, we introduce a new mode of SECM operation based on tunneling between the tip and a nanoparticle immobilized on the insulating surface. The obtained current vs. distance curves show the transition from the conventional feedback response to electron tunneling between the tip and the NP at separation distances of less than about 3 nm. In addition to high-resolution imaging of the NP topography, the tunneling mode enables measurement of the heterogeneous kinetics at a single NP without making an ohmic contact with it. The developed method should be useful for studying the effects of nanoparticle size and geometry on electrocatalytic activity in real-world applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Acceleration of gene transfection efficiency in neuroblastoma cells through polyethyleneimine/poly(methyl methacrylate core-shell magnetic nanoparticles

Directory of Open Access Journals (Sweden)

Tencomnao T

2012-06-01

Full Text Available Tewin Tencomnao,1,* Kewalin Klangthong,2,* Nuttaporn Pimpha,3 Saowaluk Chaleawlert-umpon,3 Somsak Saesoo,3 Noppawan Woramongkolchai,3 Nattika Saengkrit,31Center for Excellence in Omics-Nano Medical Technology Development Project, 2Graduate Program in Clinical Biochemistry and Molecular Medicine, Department of Clinical Chemistry, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, 3National Nanotechnology Center, National Science and Technology Development Agency, Pathumthani, Thailand*Both authors contributed equally to this workBackground: The purpose of this study was to demonstrate the potential of magnetic poly(methyl methacrylate (PMMA core/polyethyleneimine (PEI shell (mag-PEI nanoparticles, which possess high saturation magnetization for gene delivery. By using mag-PEI nanoparticles as a gene carrier, this study focused on evaluation of transfection efficiency under magnetic induction. The potential role of this newly synthesized nanosphere for therapeutic delivery of the tryptophan hydroxylase-2 (TPH-2 gene was also investigated in cultured neuronal LAN-5 cells.Methods: The mag-PEI nanoparticles were prepared by one-step emulsifier-free emulsion polymerization, generating highly loaded and monodispersed magnetic polymeric nanoparticles bearing an amine group. The physicochemical properties of the mag-PEI nanoparticles and DNA-bound mag-PEI nanoparticles were investigated using the gel retardation assay, atomic force microscopy, and zeta size measurements. The gene transfection efficiencies of mag-PEI nanoparticles were evaluated at different transfection times. Confocal laser scanning microscopy confirmed intracellular uptake of the magnetoplex. The optimal conditions for transfection of TPH-2 were selected for therapeutic gene transfection. We isolated the TPH-2 gene from the total RNA of the human medulla oblongata and cloned it into an expression vector. The plasmid containing TPH-2 was subsequently bound onto the

Improved anticancer effects of albumin-bound paclitaxel nanoparticle via augmentation of EPR effect and albumin-protein interactions using S-nitrosated human serum albumin dimer.

Science.gov (United States)

Kinoshita, Ryo; Ishima, Yu; Chuang, Victor T G; Nakamura, Hideaki; Fang, Jun; Watanabe, Hiroshi; Shimizu, Taro; Okuhira, Keiichiro; Ishida, Tatsuhiro; Maeda, Hiroshi; Otagiri, Masaki; Maruyama, Toru

2017-09-01

In the latest trend of anticancer chemotherapy research, there were many macromolecular anticancer drugs developed based on enhanced permeability and retention (EPR) effect, such as albumin bound paclitaxel nanoparticle (nab- PTX, also called Abraxane ® ). However, cancers with low vascular permeability posed a challenge for these EPR based therapeutic systems. Augmenting the intrinsic EPR effect with an intrinsic vascular modulator such as nitric oxide (NO) could be a promising strategy. S-nitrosated human serum albumin dimer (SNO-HSA Dimer) shown promising activity previously was evaluated for the synergistic effect when used as a pretreatment agent in nab-PTX therapy against various tumor models. In the high vascular permeability C26 murine colon cancer subcutaneous inoculation model, SNO-HSA Dimer enhanced tumor selectivity of nab-PTX, and attenuated myelosuppression. SNO-HSA Dimer also augmented the tumor growth inhibition of nab-PTX in low vascular permeability B16 murine melanoma subcutaneous inoculation model. Furthermore, nab-PTX therapy combined with SNO-HSA Dimer showed higher antitumor activity and improved survival rate of SUIT2 human pancreatic cancer orthotopic model. In conclusion, SNO-HSA Dimer could enhance the therapeutic effect of nab-PTX even in low vascular permeability or intractable pancreatic cancers. The possible underlying mechanisms of action of SNO-HSA Dimer were discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Covalent Immobilization of Bacillus licheniformis γ-Glutamyl Transpeptidase on Aldehyde-Functionalized Magnetic Nanoparticles

Directory of Open Access Journals (Sweden)

Meng-Chun Chi

2013-02-01

Full Text Available This work presents the synthesis and use of surface-modified iron oxide nanoparticles for the covalent immobilization of Bacillus licheniformis γ-glutamyl transpeptidase (BlGGT. Magnetic nanoparticles were prepared by an alkaline solution of divalent and trivalent iron ions, and they were subsequently treated with 3-aminopropyltriethoxysilane (APES to obtain the aminosilane-coated nanoparticles. The functional group on the particle surface and the amino group of BlGGT was then cross-linked using glutaraldehyde as the coupling reagent. The loading capacity of the prepared nanoparticles for BlGGT was 34.2 mg/g support, corresponding to 52.4% recovery of the initial activity. Monographs of transmission electron microscopy revealed that the synthesized nanoparticles had a mean diameter of 15.1 ± 3.7 nm, and the covalent cross-linking of the enzyme did not significantly change their particle size. Fourier transform infrared spectroscopy confirmed the immobilization of BlGGT on the magnetic nanoparticles. The chemical and kinetic behaviors of immobilized BlGGT are mostly consistent with those of the free enzyme. The immobilized enzyme could be recycled ten times with 36.2% retention of the initial activity and had a comparable stability respective to free enzyme during the storage period of 30 days. Collectively, the straightforward synthesis of aldehyde-functionalized nanoparticles and the efficiency of enzyme immobilization offer wide perspectives for the practical use of surface-bound BlGGT.

Trapping shape-controlled nanoparticle nucleation and growth stages via continuous-flow chemistry.

Science.gov (United States)

LaGrow, Alec P; Besong, Tabot M D; AlYami, Noktan M; Katsiev, Khabiboulakh; Anjum, Dalaver H; Abdelkader, Ahmed; Costa, Pedro M F J; Burlakov, Victor M; Goriely, Alain; Bakr, Osman M

2017-02-21

Continuous flow chemistry is used to trap the nucleation and growth stages of platinum-nickel nano-octahedra with second time resolution and high throughputs to probe their properties ex situ. The growth starts from poorly crystalline particles (nucleation) at 5 seconds, to crystalline 1.5 nm particles bounded by the {111}-facets at 7.5 seconds, followed by truncation and further growth to octahedral nanoparticles at 20 seconds.

Trapping shape-controlled nanoparticle nucleation and growth stages via continuous-flow chemistry

KAUST Repository

LaGrow, Alec P.; Besong, Tabot M.D.; AlYami, Noktan; Katsiev, Khabiboulakh; Anjum, Dalaver H.; Abdelkader, Ahmed; Da Costa, Pedro M. F. J.; Burlakov, Victor M.; Goriely, Alain; Bakr, Osman

2017-01-01

Continuous flow chemistry is used to trap the nucleation and growth stages of platinum-nickel nano-octahedra with second time resolution and high throughputs to probe their properties ex situ. The growth starts from poorly crystalline particles (nucleation) at 5 seconds, to crystalline 1.5 nm particles bounded by the {111}-facets at 7.5 seconds, followed by truncation and further growth to octahedral nanoparticles at 20 seconds.

Trapping shape-controlled nanoparticle nucleation and growth stages via continuous-flow chemistry

KAUST Repository

LaGrow, Alec P.

2017-02-06

Continuous flow chemistry is used to trap the nucleation and growth stages of platinum-nickel nano-octahedra with second time resolution and high throughputs to probe their properties ex situ. The growth starts from poorly crystalline particles (nucleation) at 5 seconds, to crystalline 1.5 nm particles bounded by the {111}-facets at 7.5 seconds, followed by truncation and further growth to octahedral nanoparticles at 20 seconds.

Hydrothermal-induced assembly of colloidal silver spheres into various nanoparticles on the basis of HTAB-modified silver mirror reaction.

Science.gov (United States)

Yu, Dabin; Yam, Vivian Wing-Wah

2005-03-31

Small colloidal silver spheres (diameter synthesis process. Adjustment of the synthesis parameters, in particular the concentrations of HTAB and [Ag(NH3)2]+, led to an obvious shape evolution of silver nanoparticles, thus resulting in the shape-selective formation of the silver nanoparticles. The monodisperse nanocubes with a well-defined crystallographical structure (a single crystal bounded by six {200} facets) have a strong tendency to assemble into two-dimensional arrays on substrates. The nanowires with uniform diameter usually existed in the form of two-dimensional alignments. The findings suggested that hydrothermal-induced assembly of small silver colloidal particles should be a convenient and effective approach to the preparation of various silver nanoparticles.

Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

Science.gov (United States)

Idros, Noorhayati; Ho, Man Yi; Pivnenko, Mike; Qasim, Malik M; Xu, Hua; Gu, Zhongze; Chu, Daping

2015-06-03

This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

Scattering by bound nucleons

International Nuclear Information System (INIS)

Tezuka, Hirokazu.

1984-10-01

Scattering of a particle by bound nucleons is discussed. Effects of nucleons that are bound in a nucleus are taken as a structure function. The way how to calculate the structure function is given. (author)

Bounds for Asian basket options

Science.gov (United States)

Deelstra, Griselda; Diallo, Ibrahima; Vanmaele, Michèle

2008-09-01

In this paper we propose pricing bounds for European-style discrete arithmetic Asian basket options in a Black and Scholes framework. We start from methods used for basket options and Asian options. First, we use the general approach for deriving upper and lower bounds for stop-loss premia of sums of non-independent random variables as in Kaas et al. [Upper and lower bounds for sums of random variables, Insurance Math. Econom. 27 (2000) 151-168] or Dhaene et al. [The concept of comonotonicity in actuarial science and finance: theory, Insurance Math. Econom. 31(1) (2002) 3-33]. We generalize the methods in Deelstra et al. [Pricing of arithmetic basket options by conditioning, Insurance Math. Econom. 34 (2004) 55-57] and Vanmaele et al. [Bounds for the price of discrete sampled arithmetic Asian options, J. Comput. Appl. Math. 185(1) (2006) 51-90]. Afterwards we show how to derive an analytical closed-form expression for a lower bound in the non-comonotonic case. Finally, we derive upper bounds for Asian basket options by applying techniques as in Thompson [Fast narrow bounds on the value of Asian options, Working Paper, University of Cambridge, 1999] and Lord [Partially exact and bounded approximations for arithmetic Asian options, J. Comput. Finance 10 (2) (2006) 1-52]. Numerical results are included and on the basis of our numerical tests, we explain which method we recommend depending on moneyness and time-to-maturity.

Market access through bound tariffs

DEFF Research Database (Denmark)

Sala, Davide; Yalcin, Erdal; Schröder, Philipp

2010-01-01

on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and longterm...

Market Access through Bound Tariffs

DEFF Research Database (Denmark)

Sala, Davide; Schröder, Philipp J.H.; Yalcin, Erdal

on the risk that exporters face in destination markets. The present paper formalizes the underlying interaction of risk, fixed export costs and firms' market entry decisions based on techniques known from the real options literature; doing so we highlight the important role of bound tariffs at the extensive...... margin of trade. We find that bound tariffs are more effective with higher risk destination markets, that a large binding overhang may still command substantial market access, and that reductions in bound tariffs generate effective market access even when bound rates are above current and long...

Reducing HAuCl4 by the C60 dianion: C60-directed self-assembly of gold nanoparticles into novel fullerene bound gold nanoassemblies

International Nuclear Information System (INIS)

Liu Wei; Gao Xiang

2008-01-01

The C 60 dianion is used to reduce tetrachloroauric acid (HAuCl 4 ) for the first time; three-dimensional C 60 bound gold (Au-C 60 ) nanoclusters are obtained from C 60 -directed self-assembly of gold nanoparticles due to the strong affinities of Au-C 60 and C 60 -C 60 . The process was monitored in situ by UV-vis-NIR spectroscopy. The resulting Au-C 60 nanoclusters were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy-dispersive spectroscopy (EDS), x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and FT-IR and Raman spectroscopies. TEM demonstrates the formation of 3D nanonetwork aggregates, which are composed of discrete gold nanocores covered with a C 60 monolayer. The SAED and XRD patterns indicate that the gold nanocores inside the capped C 60 molecules belong to the face-centred cubic crystal structure, while the C 60 molecules are amorphous. The EDS and XPS measurements validate that the Au-C 60 nanoclusters contain only Au and C elements and Au 3+ is reduced to Au 0 . FT-IR spectroscopy shows the chemiadsorption of C 60 to the gold nanocores, while Raman spectroscopy demonstrates the electron transfer from the gold nanocores to the chemiadsorbed C 60 molecules. Au-C 60 nanoclusters embedded in tetraoctyl-n-ammonium bromide (TOAB) on glassy carbon electrodes (GCEs) have been fabricated and have shown stable and well-defined electrochemical responses in aqueous solution

Proton NMR studies of functionalized nanoparticles in aqueous environments

Science.gov (United States)

Tataurova, Yulia Nikolaevna

Nanoscience is an emerging field that can provide potential routes towards addressing critical issues such as clean and sustainable energy, environmental remediation and human health. Specifically, porous nanomaterials, such as zeolites and mesoporous silica, are found in a wide range of applications including catalysis, drug delivery, imaging, environmental protection, and sensing. The characterization of the physical and chemical properties of nanocrystalline materials is essential to the realization of these innovative applications. The great advantage of porous nanocrystals is their increased external surface area that can control their biological, chemical and catalytic activities. Specific functional groups synthesized on the surface of nanoparticles are able to absorb heavy metals from the solution or target disease cells, such as cancer cells. In these studies, three main issues related to functionalized nanomaterials will be addressed through the application of nuclear magnetic resonance (NMR) techniques including: 1) surface composition and structure of functionalized nanocrystalline particles; 2) chemical properties of the guest molecules on the surface of nanomaterials, and 3) adsorption and reactivity of surface bound functional groups. Nuclear magnetic resonance (NMR) is one of the major spectroscopic techniques available for the characterization of molecular structure and conformational dynamics with atomic level detail. This thesis deals with the application of 1H solution state NMR to porous nanomaterial in an aqueous environment. Understanding the aqueous phase behavior of functionalized nanomaterials is a key factor in the design and development of safe nanomaterials because their interactions with living systems are always mediated through the aqueous phase. This is often due to a lack of fundamental knowledge in interfacial chemical and physical phenomena that occur on the surface of nanoparticles. The use of solution NMR spectroscopy results

Characterization of KCNE1 inside Lipodisq Nanoparticles for EPR Spectroscopic Studies of Membrane Proteins.

Science.gov (United States)

Sahu, Indra D; Zhang, Rongfu; Dunagan, Megan M; Craig, Andrew F; Lorigan, Gary A

2017-06-01

EPR spectroscopic studies of membrane proteins in a physiologically relevant native membrane-bound state are extremely challenging due to the complexity observed in inhomogeneity sample preparation and dynamic motion of the spin-label. Traditionally, detergent micelles are the most widely used membrane mimetics for membrane proteins due to their smaller size and homogeneity, providing high-resolution structure analysis by solution NMR spectroscopy. However, it is often difficult to examine whether the protein structure in a micelle environment is the same as that of the respective membrane-bound state. Recently, lipodisq nanoparticles have been introduced as a potentially good membrane mimetic system for structural studies of membrane proteins. However, a detailed characterization of a spin-labeled membrane protein incorporated into lipodisq nanoparticles is still lacking. In this work, lipodisq nanoparticles were used as a membrane mimic system for probing the structural and dynamic properties of the integral membrane protein KCNE1 using site-directed spin labeling EPR spectroscopy. The characterization of spin-labeled KCNE1 incorporated into lipodisq nanoparticles was carried out using CW-EPR titration experiments for the EPR spectral line shape analysis and pulsed EPR titration experiment for the phase memory time (T m ) measurements. The CW-EPR titration experiment indicated an increase in spectral line broadening with the addition of the SMA polymer which approaches close to the rigid limit at a lipid to polymer weight ratio of 1:1, providing a clear solubilization of the protein-lipid complex. Similarly, the T m titration experiment indicated an increase in T m values with the addition of SMA polymer and approaches ∼2 μs at a lipid to polymer weight ratio of 1:2. Additionally, CW-EPR spectral line shape analysis was performed on six inside and six outside the membrane spin-label probes of KCNE1 in lipodisq nanoparticles. The results indicated significant

Bound and rebound states

International Nuclear Information System (INIS)

Orzalesi, C.A.

1979-01-01

In relativistic quantum theory, bound states generate forces in the crossed channel; such forces can affect the binding and self-consistent solutions should be sought for the bound-state problem. The author investigates how self-consistency can be achieved by successive approximations, in a simple scalar model and with successive relativistic eikonal approximations (EAs). Within the generalized ladder approximation, some exact properties of the resulting ''first generation'' bound states are discussed. The binding energies in this approximation are rather small even for rather large values of the primary coupling constant. The coupling of the constituent particles to the first-generation reggeon is determined by a suitable EA and a new generalized ladder amplitude is constructed with rungs given either by the primary gluons or by the first-generation reggeons. The resulting new (second-generation) bound states are found in a reggeized EA. The size of the corrections to the binding energies due to the rebinding effects is surprisingly large. The procedure is then iterated, so as to find - again in an EA - the third-generation bound states. The procedure is found to be self-consistent already at this stage: the third-generation bound states coincide with those of second generation, and no further rebinding takes place in the higher iterations of the approximation method. Features - good and bad - of the model are discussed, as well as the possible relevance of rebinding mechanisms in hadron dynamics. (author)

Tunable Optical Properties of Metal Nanoparticle Sol-Gel Composites

Science.gov (United States)

Smith, David D.; Snow, Lanee A.; Sibille, Laurent; Ignont, Erica

2001-01-01

We demonstrate that the linear and non-linear optical properties of sol-gels containing metal nanoparticles are highly tunable with porosity. Moreover, we extend the technique of immersion spectroscopy to inhomogeneous hosts, such as aerogels, and determine rigorous bounds for the average fractional composition of each component, i.e., the porosity of the aerogel, or equivalently, for these materials, the catalytic dispersion. Sol-gels containing noble metal nanoparticles were fabricated and a significant blue-shift in the surface plasmon resonance (SPR) was observed upon formation of an aerogel, as a result of the decrease in the dielectric constant of the matrix upon supercritical extraction of the solvent. However, as a result of chemical interface damping and aggregation this blue-shift does not strictly obey standard effective medium theories. Mitigation of these complications is achieved by avoiding the use of alcohol and by annealing the samples in a reducing atmosphere.

Synthesis of platinum nanoparticles using dried Anacardium occidentale leaf and its catalytic and thermal applications.

Science.gov (United States)

Sheny, D S; Philip, Daizy; Mathew, Joseph

2013-10-01

An environment friendly approach for the synthesis of Pt nanoparticles (NPs) using dried leaf powder of Anacardium occidentale is reported. The formation of Pt NPs is monitored using UV-Vis spectrophotometer. FTIR spectra reveal that proteins are bound to Pt nanoparticles. TEM images show irregular rod shaped particles which are crystalline. The quantity of leaf powder plays a vital role in determining the size of particles. Synthesized NPs exhibit good catalytic activity in the reduction of aromatic nitrocompound. The effective thermal conductivity of synthesized Pt/water nanofluid has been measured and found to be enhanced to a good extent. Copyright © 2013 Elsevier B.V. All rights reserved.

On the role of Fe ions on magnetic properties of doped TiO2 nanoparticles

Science.gov (United States)

Tolea, F.; Grecu, M. N.; Kuncser, V.; Constantinescu, S. Gr.; Ghica, D.

2015-04-01

The role of iron doping on magnetic properties of hydrothermal anatase TiO2:57Fe (0-1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti3+ ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.

Antimicrobial Nanoparticle for the Treatment of Bacterial Infection

Science.gov (United States)

Pornpattananangkul, Dissaya

Liposomes are spherical lipid vesicles with bilayered membrane structure, which have been recognized as one of the most widely used carriers for delivering a myriad of pharmaceuticals. Liposomes can carry both hydrophilic and hydrophobic agents with high efficiency and protect them from undesired effects of external conditions. However, the applications of liposomes are usually limited by their instability during storage. They are inclined to fuse with one another immediately after preparation, resulting in undesired mixing, increase in size, and payload loss. To overcome this limitation, this dissertation will focus on the technology to stabilize liposomes during storage and destabilize at specific conditions in order to allow controllable therapeutic release, as well as demonstrate their application to treat one of the bacterial infection diseases, acne vulgaris. The first area of this research is stimuli-responsive liposomes development, where the liposomes are stabilized by introducing gold nanoparticles to adsorb to their surface. As a result, the liposomes are prevented from fusing with one another and undesirable payload release during storage or physiological environments. Moreover, therapeutic is controllably released depending on environment conditions, such as acidic pH and bacterial virulence factor. In case of acid-responsive liposomes, the bound gold nanoparticles can effectively prevent liposomes from fusing with one another at neutral pH value, while at acidic environment (e.g. pHhuman skin are typically acidic. Demonstrated by fluorescent and antimicrobial experiments, the bound gold nanoparticles effectively prevent LipoLA from fusing with one another at neutral pH value. However, at acidic condition, the gold particles detatch from LipoLA surface, allowing the fusion with P.acnes membrane and lauric acid delivery, resulting in a complete killing effect. The stimuli-responsive liposomes presented here provide a new, safe, and effective approach to

Nanoparticles-cell association predicted by protein corona fingerprints

Science.gov (United States)

Palchetti, S.; Digiacomo, L.; Pozzi, D.; Peruzzi, G.; Micarelli, E.; Mahmoudi, M.; Caracciolo, G.

2016-06-01

In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a ``protein corona'' layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ~ 100-250 nm) and surface chemistry (unmodified and PEGylated) to investigate the relationships between NP physicochemical properties (nanoparticle size, aggregation state and surface charge), protein corona fingerprints (PCFs), and NP-cell association. We found out that none of the NPs' physicochemical properties alone was exclusively able to account for association with human cervical cancer cell line (HeLa). For the entire library of NPs, a total of 436 distinct serum proteins were detected. We developed a predictive-validation modeling that provides a means of assessing the relative significance of the identified corona proteins. Interestingly, a minor fraction of the HC, which consists of only 8 PCFs were identified as main promoters of NP association with HeLa cells. Remarkably, identified PCFs have several receptors with high level of expression on the plasma membrane of HeLa cells.In a physiological environment (e.g., blood and interstitial fluids) nanoparticles (NPs) will bind proteins shaping a ``protein corona'' layer. The long-lived protein layer tightly bound to the NP surface is referred to as the hard corona (HC) and encodes information that controls NP bioactivity (e.g. cellular association, cellular signaling pathways, biodistribution, and toxicity). Decrypting this complex code has become a priority to predict the NP biological outcomes. Here, we use a library of 16 lipid NPs of varying size (Ø ~ 100-250 nm) and surface

A rapid biosynthesis route for the preparation of gold nanoparticles by aqueous extract of cypress leaves at room temperature

Science.gov (United States)

Noruzi, Masumeh; Zare, Davood; Davoodi, Daryoush

In the present study, green synthesis of gold nanoparticles was reported using the aqueous extract of cypress leaves. The reduction of gold salt with the extract of cypress leaves resulted in the formation of gold nanoparticles. Effects of extract concentration and extract pH were investigated on the size of the nanoparticles. It was found that the average particle size of synthesized gold nanoparticles depends strongly on extract concentration and extract pH. FT-IR spectroscopy showed that bioorganic capping molecules were bound to the surface of particles. X-ray techniques confirmed the formation of gold nanoparticles and their crystalline structure. The inductively coupled plasma atomic emission spectroscopy analysis displayed that the reaction progress is higher than 90% at room temperature. Gold nanoparticles were mostly spherical in shape along with some irregular shapes. Cypress is an evergreen plant and its leaves are easily available in all four seasons. Also, the rate of the reaction was high and it was completed in only 10 min. For these reasons, this method is cost-effective and environmentally friendly. Thus, it can be used in the synthesis of gold nanoparticles instead of chemical methods and other biosynthesis approaches.

Charging and Heating Dynamics of Nanoparticles in Nonthermal Plasmas

Energy Technology Data Exchange (ETDEWEB)

Kortshagen, Uwe R.

2014-08-15

The focus of this award was to understand the interactions of nanometer-sized particles with ionized gases, also called plasmas. Plasmas are widely used in the fabrication of electronic circuits such as microprocessors and memory devices, in plasma display panels, as well as in medical applications. Recently, these ionized gases are finding applications in the synthesis of advanced nanomaterials with novel properties, which are based on nanometer-sized particulate (nanoparticles) building blocks. As these nanoparticles grow in the plasma environment, they interact with the plasmas species such as electrons and ions which critically determines the nanoparticle properties. The University of Minnesota researchers conducting this project performed numerical simulations and developed analytical models that described the interaction of plasma-bound nanoparticles with the plasma ions. The plasma ions bombard the nanoparticle surface with substantial energy, which can result in the rearrangement of the nanoparticles’ atoms, giving them often desirable structures at the atomic scale. Being able to tune the ion energies allows to control the properties of nanoparticles produced in order to tailor their attributes for certain applications. For instance, when used in high efficiency light emitting devices, nanoparticles produced under high fluxes of highly energetic ions may show superior light emission to particles produced under low fluxes of less energetic ions. The analytical models developed by the University of Minnesota researchers enable the research community to easily determine the energy of ions bombarding the nanoparticles. The researchers extensively tested the validity of the analytical models by comparing them to sophisticated computer simulations based on stochastic particle modeling, also called Monte Carlo modeling, which simulated the motion of hundreds of thousands of ions and their interaction with the nanoparticle surfaces. Beyond the scientific

Intravenously administered gold nanoparticles pass through the blood-retinal barrier depending on the particle size, and induce no retinal toxicity

International Nuclear Information System (INIS)

Kim, Jeong Hun; Kim, Jin Hyoung; Yu, Young Suk; Kim, Kyu-Won; Kim, Myung Hun

2009-01-01

The retina maintains homeostasis through the blood-retinal barrier (BRB). Although it is ideal to deliver the drug to the retina via systemic administration, it is still challenging due to the BRB strictly regulating permeation from blood to the retina. Herein, we demonstrated that intravenously administered gold nanoparticles could pass through the BRB and are distributed in all retinal layers without cytotoxicity. After intravenous injection of gold nanoparticles into C57BL/6 mice, 100 nm nanoparticles were not detected in the retina whereas 20 nm nanoparticles passed through the BRB and were distributed in all retinal layers. 20 nm nanoparticles in the retina were observed in neurons (75 ± 5%), endothelial cells (17 ± 6%) and peri-endothelial glial cells (8 ± 3%), where nanoparticles were bound on the membrane. In the retina, cells containing nanoparticles did not show any structural abnormality and increase of cell death compared to cells without nanoparticles. Gold nanoparticles never affected the viability of retinal endothelial cells, astrocytes and retinoblastoma cells. Furthermore, gold nanoparticles never led to any change in expression of representative biological molecules including zonula occludens-1 and glut-1 in retinal endothelial cells, neurofilaments in differentiated retinoblastoma cells and glial fibrillary acidic protein in astrocytes. Therefore, our data suggests that small gold nanoparticles (20 nm) could be an alternative for drug delivery across the BRB, which could be safely applied in vivo.

Intravenously administered gold nanoparticles pass through the blood-retinal barrier depending on the particle size, and induce no retinal toxicity

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong Hun; Kim, Jin Hyoung; Yu, Young Suk [Department of Ophthalmology, Seoul National University College of Medicine and Seoul Artificial Eye Center, Clinical Research Institute, Seoul National University Hospital, Seoul 151744 (Korea, Republic of); Kim, Kyu-Won [NeuroVascular Coordination Research Center, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151742 (Korea, Republic of); Kim, Myung Hun, E-mail: hunin315@paran.com, E-mail: ysyu@snu.ac.kr [Department of Chemistry, Yonsei University, 134 Shinchon-dong, Seodaemun-ku, Seoul 120749 (Korea, Republic of)

2009-12-16

The retina maintains homeostasis through the blood-retinal barrier (BRB). Although it is ideal to deliver the drug to the retina via systemic administration, it is still challenging due to the BRB strictly regulating permeation from blood to the retina. Herein, we demonstrated that intravenously administered gold nanoparticles could pass through the BRB and are distributed in all retinal layers without cytotoxicity. After intravenous injection of gold nanoparticles into C57BL/6 mice, 100 nm nanoparticles were not detected in the retina whereas 20 nm nanoparticles passed through the BRB and were distributed in all retinal layers. 20 nm nanoparticles in the retina were observed in neurons (75 {+-} 5%), endothelial cells (17 {+-} 6%) and peri-endothelial glial cells (8 {+-} 3%), where nanoparticles were bound on the membrane. In the retina, cells containing nanoparticles did not show any structural abnormality and increase of cell death compared to cells without nanoparticles. Gold nanoparticles never affected the viability of retinal endothelial cells, astrocytes and retinoblastoma cells. Furthermore, gold nanoparticles never led to any change in expression of representative biological molecules including zonula occludens-1 and glut-1 in retinal endothelial cells, neurofilaments in differentiated retinoblastoma cells and glial fibrillary acidic protein in astrocytes. Therefore, our data suggests that small gold nanoparticles (20 nm) could be an alternative for drug delivery across the BRB, which could be safely applied in vivo.

Metabolism of organically bound tritium

International Nuclear Information System (INIS)

Travis, C.C.

1984-01-01

The classic methodology for estimating dose to man from environmental tritium ignores the fact that organically bound tritium in foodstuffs may be directly assimilated in the bound compartment of tissues without previous oxidation. We propose a four-compartment model consisting of a free body water compartment, two organic compartments, and a small, rapidly metabolizing compartment. The utility of this model lies in the ability to input organically bound tritium in foodstuffs directly into the organic compartments of the model. We found that organically bound tritium in foodstuffs can increase cumulative total body dose by a factor of 1.7 to 4.5 times the free body water dose alone, depending on the bound-to-loose ratio of tritium in the diet. Model predictions are compared with empirical measurements of tritium in human urine and tissue samples, and appear to be in close agreement. 10 references, 4 figures, 3 tables

Highly Hydrophilic Thin-Film Composite Forward Osmosis Membranes Functionalized with Surface-Tailored Nanoparticles

KAUST Repository

Tiraferri, Alberto

2012-09-26

Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion. © 2012 American Chemical Society.

Bound states in string nets

Science.gov (United States)

Schulz, Marc Daniel; Dusuel, Sébastien; Vidal, Julien

2016-11-01

We discuss the emergence of bound states in the low-energy spectrum of the string-net Hamiltonian in the presence of a string tension. In the ladder geometry, we show that a single bound state arises either for a finite tension or in the zero-tension limit depending on the theory considered. In the latter case, we perturbatively compute the binding energy as a function of the total quantum dimension. We also address this issue in the honeycomb lattice where the number of bound states in the topological phase depends on the total quantum dimension. Finally, the internal structure of these bound states is analyzed in the zero-tension limit.

Bounding approaches to system identification

CERN Document Server

Norton, John; Piet-Lahanier, Hélène; Walter, Éric

1996-01-01

In response to the growing interest in bounding error approaches, the editors of this volume offer the first collection of papers to describe advances in techniques and applications of bounding of the parameters, or state variables, of uncertain dynamical systems. Contributors explore the application of the bounding approach as an alternative to the probabilistic analysis of such systems, relating its importance to robust control-system design.

Novel Gd nanoparticles enhance vascular contrast for high-resolution magnetic resonance imaging.

Directory of Open Access Journals (Sweden)

Tot Bui

2010-09-01

Full Text Available Gadolinium (Gd, with its 7 unpaired electrons in 4f orbitals that provide a very large magnetic moment, is proven to be among the best agents for contrast enhanced MRI. Unfortunately, the most potent MR contrast agent based on Gd requires relatively high doses of Gd. The Gd-chelated to diethylene-triamine-penta-acetic acid (DTPA, or other derivatives (at 0.1 mmole/kg recommended dose, distribute broadly into tissues and clear through the kidney. These contrast agents carry the risk of Nephrogenic Systemic Fibrosis (NSF, particularly in kidney impaired subjects. Thus, Gd contrast agents that produce higher resolution images using a much lower Gd dose could address both imaging sensitivity and Gd safety.To determine whether a biocompatible lipid nanoparticle with surface bound Gd can improve MRI contrast sensitivity, we constructed Gd-lipid nanoparticles (Gd-LNP containing lipid bound DTPA and Gd. The Gd-LNP were intravenously administered to rats and MR images collected. We found that Gd in Gd-LNP produced a greater than 33-fold higher longitudinal (T(1 relaxivity, r(1, constant than the current FDA approved Gd-chelated contrast agents. Intravenous administration of these Gd-LNP at only 3% of the recommended clinical Gd dose produced MRI signal-to-noise ratios of greater than 300 in all vasculatures. Unlike current Gd contrast agents, these Gd-LNP stably retained Gd in normal vasculature, and are eliminated predominately through the biliary, instead of the renal system. Gd-LNP did not appear to accumulate in the liver or kidney, and was eliminated completely within 24 hrs.The novel Gd-nanoparticles provide high quality contrast enhanced vascular MRI at 97% reduced dose of Gd and do not rely on renal clearance. This new agent is likely to be suitable for patients exhibiting varying degrees of renal impairment. The simple and adaptive nanoparticle design could accommodate ligand or receptor coating for drug delivery optimization and in vivo drug

On the role of Fe ions on magnetic properties of doped TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Tolea, F.; Grecu, M. N., E-mail: mgrecu@infim.ro; Kuncser, V.; Constantinescu, S. Gr.; Ghica, D. [National Institute of Materials Physics (NIMP), Mǎgurele-Ilfov 077125 (Romania)

2015-04-06

The role of iron doping on magnetic properties of hydrothermal anatase TiO{sub 2}:{sup 57}Fe (0–1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti{sup 3+} ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.

Preventative vaccine-loaded mannosylated chitosan nanoparticles intended for nasal mucosal delivery enhance immune responses and potent tumor immunity.

Science.gov (United States)

Yao, Wenjun; Peng, Yixing; Du, Mingzhu; Luo, Juan; Zong, Li

2013-08-05

Chitosan (CS) has been extensively used as a protein drug and gene delivery carrier, but its delivery efficiency is unsatisfactory. In this study, a mannose ligand was used to modify CS, which could enhance the delivery efficiency of CS via mannose receptor-mediated endocytosis. A preventative anti-GRP DNA vaccine (pCR3.1-VS-HSP65-TP-GRP6-M2, pGRP) was condensed with mannosylated chitosan (MCS) to form MCS/pGRP nanoparticles. Nanoparticles were intranasally administered in a subcutaneous mice prostate carcinoma model to evaluate the efficacy on inhibition of the growth of tumor cells. The titers of anti-GRP IgG that lasted for 11 weeks were significantly higher than that for administration of CS/pGRP nanoparticles (p intramuscular administration of a pGRP solution (p nanoparticles could suppress the growth of tumor cells. The average tumor weight (0.79 ± 0.30 g) was significantly lower than that in the CS/pGRP nanoparticle group (1.69 ± 0.15 g) (p nanoparticles bound with C-type lectin receptors on macrophages. MCS was an efficient targeting gene delivery carrier and could be used in antitumor immunotherapy.

Effects of interband transitions on Faraday rotation in metallic nanoparticles.

Science.gov (United States)

Wysin, G M; Chikan, Viktor; Young, Nathan; Dani, Raj Kumar

2013-08-14

The Faraday rotation in metallic nanoparticles is considered based on a quantum model for the dielectric function ϵ(ω) in the presence of a DC magnetic field B. We focus on effects in ϵ(ω) due to interband transitions (IBTs), which are important in the blue and ultraviolet for noble metals used in plasmonics. The dielectric function is found using the perturbation of the electron density matrix due to the optical field of the incident electromagnetic radiation. The calculation is applied to transitions between two bands (d and p, for example) separated by a gap, as one finds in gold at the L-point of the Fermi surface. The result of the DC magnetic field is a shift in the effective optical frequency causing IBTs by ±μBB/ħ, where opposite signs are associated with left/right circular polarizations. The Faraday rotation for a dilute solution of 17 nm diameter gold nanoparticles is measured and compared with both the IBT theory and a simpler Drude model for the bound electron response. Effects of the plasmon resonance mode on Faraday rotation in nanoparticles are also discussed.

Bounded Intention Planning Revisited

OpenAIRE

Sievers Silvan; Wehrle Martin; Helmert Malte

2014-01-01

Bounded intention planning provides a pruning technique for optimal planning that has been proposed several years ago. In addition partial order reduction techniques based on stubborn sets have recently been investigated for this purpose. In this paper we revisit bounded intention planning in the view of stubborn sets.

Bounded Gaussian process regression

DEFF Research Database (Denmark)

Jensen, Bjørn Sand; Nielsen, Jens Brehm; Larsen, Jan

2013-01-01

We extend the Gaussian process (GP) framework for bounded regression by introducing two bounded likelihood functions that model the noise on the dependent variable explicitly. This is fundamentally different from the implicit noise assumption in the previously suggested warped GP framework. We...... with the proposed explicit noise-model extension....

A symmetric Roos bound for linear codes

NARCIS (Netherlands)

Duursma, I.M.; Pellikaan, G.R.

2006-01-01

The van Lint–Wilson AB-method yields a short proof of the Roos bound for the minimum distance of a cyclic code. We use the AB-method to obtain a different bound for the weights of a linear code. In contrast to the Roos bound, the role of the codes A and B in our bound is symmetric. We use the bound

Biological Mechanism of Silver Nanoparticle Toxicity

Science.gov (United States)

Armstrong, Najealicka Nicole

Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities above that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, these investigations were attempted to monitor the effects of AgNPs at a non-lethal concentration on wild type Drosophila melanogaster by exposing them to nanoparticles throughout their development. All adult flies raised in AgNP doped food indicated that of not more than 50 mg/L had no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised after AgNP feeding. The determination of the amount of free ionic silver (Ag+) indicated that the observed biological effects had resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, were decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Furthermore, copper supplementation restored the loss of AgNP induced demelanization, and the reduction of functional Ctr1 in Ctr1 heterozygous mutants caused the flies to be resistant to demelanization. Consequently, these studies proposed a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explained the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, these investigations demonstrated that Drosophila, an established genetic model system, can be well utilized for further

Bounded Tamper Resilience

DEFF Research Database (Denmark)

Damgård, Ivan Bjerre; Faust, Sebastian; Mukherjee, Pratyay

2013-01-01

Related key attacks (RKAs) are powerful cryptanalytic attacks where an adversary can change the secret key and observe the effect of such changes at the output. The state of the art in RKA security protects against an a-priori unbounded number of certain algebraic induced key relations, e.......g., affine functions or polynomials of bounded degree. In this work, we show that it is possible to go beyond the algebraic barrier and achieve security against arbitrary key relations, by restricting the number of tampering queries the adversary is allowed to ask for. The latter restriction is necessary......-protocols (including the Okamoto scheme, for instance) are secure even if the adversary can arbitrarily tamper with the prover’s state a bounded number of times and obtain some bounded amount of leakage. Interestingly, for the Okamoto scheme we can allow also independent tampering with the public parameters. We show...

P2-16: Dual-Bound Model and the Role of Time Bound in Perceptual Decision Making

Directory of Open Access Journals (Sweden)

Daeseob Lim

2012-10-01

Full Text Available The diffusion model (DM encapsulates the dynamics of perceptual decision within a ‘diffusion field’ that is defined by a basis with sensory-evidence (SE and time vectors. At the core of the DM, it assumes that a decision is not made until an evidence particle drifts in the diffusion field and eventually hits one of the two pre-fixed bounds defined in the SE axis. This assumption dictates when and which choice is made by referring to when and which bound will be hit by the evidence particle. What if urgency pressures the decision system to make a choice even when the evidence particle has yet hit the SE bound? Previous modeling attempts at coping with time pressure, despite differences in detail, all manipulated the coordinate of SE bounds. Here, we offer a novel solution by adopting another bound on the time axis. This ‘dual-bound’ model (DBM posits that decisions can also be made when the evidence particle hits a time bound, which is determined on a trial-by-trial basis by a ‘perceived time interval’ – how long the system can stay in the ‘diffusion’ field. The classic single-bound model (SBM exhibited systematic errors in predicting both the reaction time distributions and the time-varying bias in choice. Those errors were not corrected by previously proposed variants of the SBM until the time bound was introduced. The validity of the DBM was further supported by the strong across-individual correlation between observed precision of interval timing and the predicted trial-by-trial variability of the time bound.

Detection of Salmonella typhi utilizing bioconjugated fluorescent polymeric nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Jain, Swati, E-mail: swatijain.iitd@gmail.com; Chattopadhyay, Sruti, E-mail: sruticiitd@gmail.com; Jackeray, Richa; Abid, Zainul; Singh, Harpal, E-mail: harpal2000@yahoo.com [Centre for Biomedical Engineering, Indian Institute of Technology-Delhi (India)

2016-05-15

Present work demonstrates effective utilization of functionalized polymeric fluorescent nanoparticles as biosensing probe for the detection of Salmonella typhi bacteria on modified polycarbonate (PC) filters in about 3 h. Antibody modified-PC membranes were incubated with contaminated bacterial water for selective capturing which were detected by synthesized novel bioconjugate probe. Core–shell architecture of polymeric nanoparticles endows them with aqueous stabilization and keto-enolic functionalities making them usable for covalently linking S. typhi antibodies without any crosslinker or activator. Bradford analysis revealed that one nanoparticle has an average of 3.51 × 10{sup −19} g or 21 × 10{sup 4} bound S. typhi Ab molecules. Analysis of the regions of interest (ROI) in fluorescent micrographs of modified fluoroimmunoassay showed higher detection sensitivity of 5 × 10{sup 2} cells/mL due to signal amplification unlike conventional naked dye FITC-Ab conjugate. Fluorescence of pyrene dye remained same on immobilization of biomolecules and nanoparticles showed stable fluorescent intensity under prolong exposure to laser owing to protective polymeric layer allowing accurate identification of bacteria. Surface-functionalized PC matrix and fluorescent label NPs permit covalent interactions among biomolecules enhancing signal acquisitions showing higher detection efficiency as compared to conventional microtiter plate-based system. Our novel immunoassay has the potential to be explored as rapid detection method for identifying S. typhi contaminations in water.Graphical Abstract.

Detection of Salmonella typhi utilizing bioconjugated fluorescent polymeric nanoparticles

International Nuclear Information System (INIS)

Jain, Swati; Chattopadhyay, Sruti; Jackeray, Richa; Abid, Zainul; Singh, Harpal

2016-01-01

Present work demonstrates effective utilization of functionalized polymeric fluorescent nanoparticles as biosensing probe for the detection of Salmonella typhi bacteria on modified polycarbonate (PC) filters in about 3 h. Antibody modified-PC membranes were incubated with contaminated bacterial water for selective capturing which were detected by synthesized novel bioconjugate probe. Core–shell architecture of polymeric nanoparticles endows them with aqueous stabilization and keto-enolic functionalities making them usable for covalently linking S. typhi antibodies without any crosslinker or activator. Bradford analysis revealed that one nanoparticle has an average of 3.51 × 10"−"1"9 g or 21 × 10"4 bound S. typhi Ab molecules. Analysis of the regions of interest (ROI) in fluorescent micrographs of modified fluoroimmunoassay showed higher detection sensitivity of 5 × 10"2 cells/mL due to signal amplification unlike conventional naked dye FITC-Ab conjugate. Fluorescence of pyrene dye remained same on immobilization of biomolecules and nanoparticles showed stable fluorescent intensity under prolong exposure to laser owing to protective polymeric layer allowing accurate identification of bacteria. Surface-functionalized PC matrix and fluorescent label NPs permit covalent interactions among biomolecules enhancing signal acquisitions showing higher detection efficiency as compared to conventional microtiter plate-based system. Our novel immunoassay has the potential to be explored as rapid detection method for identifying S. typhi contaminations in water.Graphical Abstract

Direct Measurement of Photon Recoil from a Levitated Nanoparticle

Science.gov (United States)

Jain, Vijay; Gieseler, Jan; Moritz, Clemens; Dellago, Christoph; Quidant, Romain; Novotny, Lukas

2016-06-01

The momentum transfer between a photon and an object defines a fundamental limit for the precision with which the object can be measured. If the object oscillates at a frequency Ω0 , this measurement backaction adds quanta ℏΩ0 to the oscillator's energy at a rate Γrecoil, a process called photon recoil heating, and sets bounds to coherence times in cavity optomechanical systems. Here, we use an optically levitated nanoparticle in ultrahigh vacuum to directly measure Γrecoil. By means of a phase-sensitive feedback scheme, we cool the harmonic motion of the nanoparticle from ambient to microkelvin temperatures and measure its reheating rate under the influence of the radiation field. The recoil heating rate is measured for different particle sizes and for different excitation powers, without the need for cavity optics or cryogenic environments. The measurements are in quantitative agreement with theoretical predictions and provide valuable guidance for the realization of quantum ground-state cooling protocols and the measurement of ultrasmall forces.

Detection of tyrosine hydroxylase in dopaminergic neuron cell using gold nanoparticles-based barcode DNA.

Science.gov (United States)

An, Jeung Hee; Oh, Byung-Keun; Choi, Jeong Woo

2013-04-01

Tyrosine hydroxylase, the rate-limiting enzyme of catecholamine biosysthesis, is predominantly expressed in several cell groups within the brain, including the dopaminergic neurons of the substantia nigra and ventral tegmental area. We evaluated the efficacy of this protein-detection method in detecting tyrosine hydroxylase in normal and oxidative stress damaged dopaminergic cells. In this study, a coupling of DNA barcode and bead-based immnunoassay for detecting tyrosine hydroxylaser with PCR-like sensitivity is reported. The method relies on magnetic nanoparticles with antibodies and nanoparticles that are encoded with DNA and antibodies that can sandwich the target protein captured by the nanoparticle-bound antibodies. The aggregate sandwich structures are magnetically separated from solution, and treated to remove the conjugated barcode DNA. The DNA barcodes were identified by PCR analysis. The concentration of tyrosine hydroxylase in dopaminergic cell can be easily and rapidly detected using bio-barcode assay. The bio-barcode assay is a rapid and high-throughput screening tool to detect of neurotransmitter such as dopamine.

Shape Effects in Nanoparticle-Based Imaging Agents

Science.gov (United States)

Culver, Kayla Shani Brook

At the nanoscale, material properties become highly size and shape dependent. These properties can be manipulated and exploited for a variety of biomedical applications, including sensing, drug delivery, diagnostics, and imaging. In particular, nanoparticles of different materials, sizes and shapes have been developed as high-performance contrast agents for optical, electron, and medical imaging. In this thesis, I focus on gold nanoparticles because they are widely used as contrast agents in multiple types of imaging modalities. Additionally, the surface of gold can be readily functionalized with ligands and the structure of the particles can be manipulated to modulate their performance as imaging agents. The properties of nanoparticles can generate contrast directly. For example, the light scattering properties of gold particles can be visualized in optical microscopy, the high electron density of gold produces contrast in electron microscopy, and the x-ray absorption properties of gold can be detected in medical x-ray and computed tomography imaging. Alternatively, the properties of the nanomaterial can be exploited to modulate the signal produced by other molecules that are bound to the particle surface. The light emission of molecular fluorophores can be quenched or dramatically increased by coupling to the optical field enhancements of gold nanoparticles, and the performance of gadolinium (Gd(III))-based magnetic resonance imaging (MRI) contrast agents can be increased by coupling to the rotational motion of nanoparticles. In this dissertation, I focus specifically on how the structure of star-shaped gold particles (nanostars) can be exploited as single-particle optical probes and to dramatically enhance the relaxivity of Gd(III) bound to the surface. Differential interference contrast (DIC) is a type of wide-field diffraction-limited optical microscopy that is commonly used by biologists to image cells without labels. Here, I demonstrate the DIC can be used

Spectral dependence of nonlinear optical absorption of silica glass with copper nanoparticles

International Nuclear Information System (INIS)

Golubev, A N; Nikitin, S I; Smirnov, M A; Stepanov, A L

2011-01-01

The nonlinear optical properties of silica glass with copper nanoparticles synthesized by ion implantation were investigated by z-scan method in nanosecond time scale. The reverse saturation absorption (RSA) at the wavelength range of 450–540 nm and saturation absorption (SA) at 550–585 nm were observed. It was supposed that the two-photon electron absorption from bound of d-states determined the RSA effect and the SA is due to saturation of plasmon excitation.

A Feasibility Study of Bevacizumab Plus Dose-Dense Doxorubicin–Cyclophosphamide (AC) Followed by Nanoparticle Albumin–Bound Paclitaxel in Early-Stage Breast Cancer

Science.gov (United States)

McArthur, Heather L.; Rugo, Hope; Nulsen, Benjamin; Hawks, Laura; Grothusen, Jill; Melisko, Michelle; Moasser, Mark; Paulson, Matthew; Traina, Tiffany; Patil, Sujata; Zhou, Qin; Steingart, Richard; Dang, Chau; Morrow, Monica; Cordeiro, Peter; Fornier, Monica; Park, John; Seidman, Andrew; Lake, Diana; Gilewski, Theresa; Theodoulou, Maria; Modi, Shanu; D’Andrea, Gabriella; Sklarin, Nancy; Robson, Mark; Moynahan, Mary Ellen; Sugarman, Steven; Sealey, Jane E.; Laragh, John H.; Merali, Carmen; Norton, Larry; Hudis, Clifford A.; Dickler, Maura N.

2016-01-01

Purpose Bevacizumab confers benefits in metastatic breast cancer but may be more effective as adjuvant therapy. We evaluated the cardiac safety of bevacizumab plus dose-dense doxorubicin–cyclophosphamide (ddAC)→nanoparticle albumin−bound (nab)-paclitaxel in human epidermal growth factor receptor 2 normal early-stage breast cancer. Experimental Design Eighty patients with normal left ventricular ejection fraction (LVEF) were enrolled. Bevacizumab was administered for 1 year, concurrently with ddAC→nab-paclitaxel then as a single agent. LVEF was evaluated at months 0, 2, 6, 9, and 18. This regimen was considered safe if fewer than three cardiac events or fewer than two deaths from left ventricular dysfunction occurred. Correlative studies of cardiac troponin (cTn) and plasma renin activity (PRA) were conducted. Results The median age was 48 years (range, 27−75 years), and baseline LVEF was 68% (53%−82%). After 39 months’ median follow-up (5−45 months): median LVEF was 68% (53%−80%) at 2 months (n=78), 64% (51%−77%) at 6 months (n=66), 63% (48%−77%) at 9 months (n=61), and 66% (42%−76%) at 18 months (n=54). One patient developed symptomatic LV dysfunction at month 15. Common toxicities necessitating treatment discontinuation were hypertension (HTN, 4%), wound-healing complications (4%), and asymptomatic LVEF declines (4%). Neither cTn nor PRA predicted CHF or HTN, respectively. Conclusions Bevacizumab with ddAC→nab-paclitaxel had a low rate of cardiac events; cTn and PRA levels are not predictive of CHF or HTN, respectively. The efficacy of bevacizumab as adjuvant treatment will be established in several ongoing phase III trials. PMID:21350003

Instanton bound states in ABJM theory

Energy Technology Data Exchange (ETDEWEB)

Hatsuda, Yasuyuki [DESY Hamburg (Germany). Theory Group; Tokyo Institute of Technology (Japan). Dept. of Physics; Moriyama, Sanefumi [Nagoya Univ. (Japan). Kobayashi Maskawa Inst. and Graduate School of Mathematics; Okuyama, Kazumi [Shinshu Univ., Matsumoto, Nagano (Japan). Dept. of Physics

2013-06-15

The partition function of the ABJM theory receives non-perturbative corrections due to instanton effects. We study these non-perturbative corrections, including bound states of worldsheet instantons and membrane instantons, in the Fermi-gas approach. We require that the total non-perturbative correction should be always finite for arbitrary Chern-Simons level. This finiteness is realized quite non-trivially because each bound state contribution naively diverges at some levels. The poles of each contribution should be canceled out in total. We use this pole cancellation mechanism to find unknown bound state corrections from known ones. We conjecture a general expression of the bound state contribution. Summing up all the bound state contributions, we find that the effect of bound states is simply incorporated into the worldsheet instanton correction by a redefinition of the chemical potential in the Fermi-gas system. Analytic expressions of the 3- and 4-membrane instanton corrections are also proposed.

Diazonium-derived aryl films on gold nanoparticles: evidence for a carbon-gold covalent bond.

Science.gov (United States)

Laurentius, Lars; Stoyanov, Stanislav R; Gusarov, Sergey; Kovalenko, Andriy; Du, Rongbing; Lopinski, Gregory P; McDermott, Mark T

2011-05-24

Tailoring the surface chemistry of metallic nanoparticles is generally a key step for their use in a wide range of applications. There are few examples of organic films covalently bound to metal nanoparticles. We demonstrate here that aryl films are formed on gold nanoparticles from the spontaneous reduction of diazonium salts. The structure and the bonding of the film is probed with surface-enhanced Raman scattering (SERS). Extinction spectroscopy and SERS show that a nitrobenzene film forms on gold nanoparticles from the corresponding diazonium salt. Comparison of the SERS spectrum with spectra computed from density functional theory models reveals a band characteristic of a Au-C stretch. The observation of this stretch is direct evidence of a covalent bond. A similar band is observed in high-resolution electron energy loss spectra of nitrobenzene layers on planar gold. The bonding of these types of films through a covalent interaction on gold is consistent with their enhanced stability observed in other studies. These findings provide motivation for the use of diazonium-derived films on gold and other metals in applications where high stability and/or strong adsorbate-substrate coupling are required.

The use of Bayesian networks for nanoparticle risk forecasting: model formulation and baseline evaluation.

Science.gov (United States)

Money, Eric S; Reckhow, Kenneth H; Wiesner, Mark R

2012-06-01

We describe the use of Bayesian networks as a tool for nanomaterial risk forecasting and develop a baseline probabilistic model that incorporates nanoparticle specific characteristics and environmental parameters, along with elements of exposure potential, hazard, and risk related to nanomaterials. The baseline model, FINE (Forecasting the Impacts of Nanomaterials in the Environment), was developed using expert elicitation techniques. The Bayesian nature of FINE allows for updating as new data become available, a critical feature for forecasting risk in the context of nanomaterials. The specific case of silver nanoparticles (AgNPs) in aquatic environments is presented here (FINE(AgNP)). The results of this study show that Bayesian networks provide a robust method for formally incorporating expert judgments into a probabilistic measure of exposure and risk to nanoparticles, particularly when other knowledge bases may be lacking. The model is easily adapted and updated as additional experimental data and other information on nanoparticle behavior in the environment become available. The baseline model suggests that, within the bounds of uncertainty as currently quantified, nanosilver may pose the greatest potential risk as these particles accumulate in aquatic sediments. Copyright © 2012 Elsevier B.V. All rights reserved.

Preparation of Ulex europaeus lectin-gliadin nanoparticle conjugates and their interaction with gastrointestinal mucus.

Science.gov (United States)

Ezpeleta, I; Arangoa, M A; Irache, J M; Stainmesse, S; Chabenat, C; Popineau, Y; Orecchioni, A M

1999-11-25

One approach to improve the bioavailability and efficiency of drugs consists of the association of a ligand (i.e. lectins), showing affinity for biological structures located on the mucosa surfaces, to nanoparticulate drug delivery systems. In this context, Ulex europaeus lectin-gliadin nanoparticle conjugates (UE-GNP) were prepared with the aim of evaluating their in vitro bioadhesive properties. The lectin was fixed by a covalent procedure to gliadin nanoparticles by a two-stage carbodiimide method. Typically, the amount of bound lectin was calculated to be approximately 15 microg lectin/mg nanoparticle, which represented a coupling efficiency of approximately 16% of the initial lectin concentration. In addition, the activity of these conjugates was tested with bovine submaxillary gland mucin (BSM) and the level of binding to this mucin was always much greater with UE-GNP than with controls (gliadin nanoparticles). However, the presence of 50 micromol fucose, which is the reported specific sugar for U. europaeus lectin, specifically inhibited the activity of these conjugates and, therefore, the UE-GNP binding to BSM was attenuated by 70%. These results clearly showed that the activity and specificity of U. europaeus lectin was preserved after covalent coupling to these biodegradable carriers.

Career Development and Personal Functioning Differences between Work-Bound and Non-Work Bound Students

Science.gov (United States)

Creed, Peter A.; Patton, Wendy; Hood, Michelle

2010-01-01

We surveyed 506 Australian high school students on career development (exploration, planning, job-knowledge, decision-making, indecision), personal functioning (well-being, self-esteem, life satisfaction, school satisfaction) and control variables (parent education, school achievement), and tested differences among work-bound, college-bound and…

Role of proteins in controlling selenium nanoparticle size

International Nuclear Information System (INIS)

Dobias, J; Suvorova, E I; Bernier-Latmani, R

2011-01-01

This work investigates the potential for harnessing the association of bacterial proteins to biogenic selenium nanoparticles (SeNPs) to control the size distribution and the morphology of the resultant SeNPs. We conducted a proteomic study and compared proteins associated with biogenic SeNPs produced by E. coli to chemically synthesized SeNPs as well as magnetite nanoparticles. We identified four proteins (AdhP, Idh, OmpC, AceA) that bound specifically to SeNPs and observed a narrower size distribution as well as more spherical morphology when the particles were synthesized chemically in the presence of proteins. A more detailed study of AdhP (alcohol dehydrogenase propanol-preferring) confirmed the strong affinity of this protein for the SeNP surface and revealed that this protein controlled the size distribution of the SeNPs and yielded a narrow size distribution with a three-fold decrease in the median size. These results support the assertion that protein may become an important tool in the industrial-scale synthesis of SeNPs of uniform size and properties.

Determining Normal-Distribution Tolerance Bounds Graphically

Science.gov (United States)

Mezzacappa, M. A.

1983-01-01

Graphical method requires calculations and table lookup. Distribution established from only three points: mean upper and lower confidence bounds and lower confidence bound of standard deviation. Method requires only few calculations with simple equations. Graphical procedure establishes best-fit line for measured data and bounds for selected confidence level and any distribution percentile.

Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils

Energy Technology Data Exchange (ETDEWEB)

Ahrentorp, Fredrik; Blomgren, Jakob; Jonasson, Christian; Sarwe, Anna [Acreo Swedish ICT AB, Arvid Hedvalls Backe 4, Göteborg (Sweden); Sepehri, Sobhan; Eriksson, Emil; Kalaboukhov, Alexei; Jesorka, Aldo; Winkler, Dag [Department of Microtechnology and Nanoscience – MC2, Chalmers University of Technology, Göteborg (Sweden); Schneiderman, Justin F. [Institute of Neuroscience and Physiology, University of Gothenburg and MedTech West, Göteborg (Sweden); Nilsson, Mats [Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm (Sweden); Albert, Jan [Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm (Sweden); Department of Clinical Microbiology, Karolinska University Hospital, Stockholm (Sweden); Zardán Gómez de la Torre, Teresa; Strømme, Maria [Uppsala University, Uppsala (Sweden); Johansson, Christer, E-mail: christer.johansson@acreo.se [Acreo Swedish ICT AB, Arvid Hedvalls Backe 4, Göteborg (Sweden)

2017-04-01

We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 µm. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 µL) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD. - Highlights: • Biosensing using Brownian relaxation of functionalized magnetic nanoparticles. • Rolling circle amplification and magnetic nanoparticles enables biosensing. • Theoretical limit of detection estimated from the signal noise gives about 55 fM.

Binding energies of two deltas bound states

International Nuclear Information System (INIS)

Sato, Hiroshi; Saito, Koichi.

1982-06-01

Bound states of the two-deltas system are investigated by employing the realistic one boson exchange potential. It is found that there exist many bound states in each isospin channel and also found that the tensor interaction plays important role in producing these bound states. Relationship between these bound states and dibaryon resonances is discussed. (J.P.N.)

In vitro effects of metal oxide nanoparticles on barley oxalate oxidase

Energy Technology Data Exchange (ETDEWEB)

Chauhan, Nidhi [M. D. University, Department of Biochemistry (India); Hooda, Vinita [M. D. University, Department of Botany (India); Pundir, C. S., E-mail: pundircs@rediffmail.com [M. D. University, Department of Biochemistry (India)

2013-03-15

Barley oxalate oxidase (OxO), a manganese-containing protein, is largely employed for determination of oxalate in various biologic materials. The present report describes in vitro effects of nanoparticles (NPs) of three metal oxides, i.e., zinc oxide (ZnO), copper oxide (CuO), and manganese oxide (MnO{sub 2}), on the activity and stability of OxO purified from barley roots. The transmission electron microscopy and X-ray diffraction studies of these NPs revealed their very fine crystalline structure with the dimeter in the range 30-70, 50-60, and 20-60 nm for ZnO NPs, CuO NPs, and MnO{sub 2} NPs, respectively. The addition of suspension of these three NPs into assay mixture of enzyme individually, led to the adsorption of OxO over their surface, as confirmed by Fourier transform infrared spectra and UV-Vis spectroscopic studies. Compared to free enzyme, MnO{sub 2} NPs-bound enzyme showed improved activity (35 % stimulation at 2.5 mg/ml concentration), while ZnO NPs- and CuO NPs-bound enzyme had no substantial improvement. The kinetic properties of individually NPs-bound enzyme were studied and compared with those of free enzyme. The MnO{sub 2} NPs-bound enzyme also showed marked improvement in its storage and thermal stability compared to free enzyme.

In vitro effects of metal oxide nanoparticles on barley oxalate oxidase

Science.gov (United States)

Chauhan, Nidhi; Hooda, Vinita; Pundir, C. S.

2013-03-01

Barley oxalate oxidase (OxO), a manganese-containing protein, is largely employed for determination of oxalate in various biologic materials. The present report describes in vitro effects of nanoparticles (NPs) of three metal oxides, i.e., zinc oxide (ZnO), copper oxide (CuO), and manganese oxide (MnO2), on the activity and stability of OxO purified from barley roots. The transmission electron microscopy and X-ray diffraction studies of these NPs revealed their very fine crystalline structure with the dimeter in the range 30-70, 50-60, and 20-60 nm for ZnO NPs, CuO NPs, and MnO2 NPs, respectively. The addition of suspension of these three NPs into assay mixture of enzyme individually, led to the adsorption of OxO over their surface, as confirmed by Fourier transform infrared spectra and UV-Vis spectroscopic studies. Compared to free enzyme, MnO2 NPs-bound enzyme showed improved activity (35 % stimulation at 2.5 mg/ml concentration), while ZnO NPs- and CuO NPs-bound enzyme had no substantial improvement. The kinetic properties of individually NPs-bound enzyme were studied and compared with those of free enzyme. The MnO2 NPs-bound enzyme also showed marked improvement in its storage and thermal stability compared to free enzyme.

Simulations of Interdigitated Electrode Interactions with Gold Nanoparticles for Impedance-Based Biosensing Applications

Directory of Open Access Journals (Sweden)

Scott MacKay

2015-09-01

Full Text Available In this paper, we describe a point-of-care biosensor design. The uniqueness of our design is in its capability for detecting a wide variety of target biomolecules and the simplicity of nanoparticle enhanced electrical detection. The electrical properties of interdigitated electrodes (IDEs and the mechanism for gold nanoparticle-enhanced impedance-based biosensor systems based on these electrodes are simulated using COMSOL Multiphysics software. Understanding these properties and how they can be affected is vital in designing effective biosensor devices. Simulations were used to show electrical screening develop over time for IDEs in a salt solution, as well as the electric field between individual digits of electrodes. Using these simulations, it was observed that gold nanoparticles bound closely to IDEs can lower the electric field magnitude between the digits of the electrode. The simulations are also shown to be a useful design tool in optimizing sensor function. Various different conditions, such as electrode dimensions and background ion concentrations, are shown to have a significant impact on the simulations.

Variational lower bound on the scattering length

International Nuclear Information System (INIS)

Rosenberg, L.; Spruch, L.

1975-01-01

The scattering length A characterizes the zero-energy scattering of one system by another. It was shown some time ago that a variational upper bound on A could be obtained using methods, of the Rayleigh-Ritz type, which are commonly employed to obtain upper bounds on energy eigenvalues. Here we formulate a method for obtaining a variational lower bound on A. Once again the essential idea is to express the scattering length as a variational estimate plus an error term and then to reduce the problem of bounding the error term to one involving bounds on energy eigenvalues. In particular, the variational lower bound on A is rigorously established provided a certin modified Hamiltonian can be shown to have no discrete states lying below the level of the continuum threshold. It is unfortunately true that necessary conditions for the existence of bound states are not available for multiparticle systems in general. However, in the case of positron-atom scattering the adiabatic approximation can be introduced as an (essentially) solvable comparison problem to rigorously establish the nonexistence of bound states of the modified Hamiltonian. It has recently been shown how the validity of the variational upper bound on A can be maintained when the target ground-state wave function is imprecisely known. Similar methods can be used to maintain the variational lower bound on A. Since the bound is variational, the error in the calculated scattering length will be of second order in the error in the wave function. The use of the adiabatic approximation in the present context places no limitation in principle on the accuracy achievable

What nanomedicine in the clinic right now really forms nanoparticles?

Science.gov (United States)

Svenson, Sonke

2014-01-01

Some researchers believe nanomedicine will revolutionize healthcare and medicine through transformative new therapeutic tools. Nanocarriers, utilized to transport actives to the target site, are constructed from a wide range of materials. Nanocarriers can be grouped into self-assembling (liposomes, micelles), processed (nanoparticles, emulsions), and chemically bound (dendrimers, silica-based carriers, carbon nanotubes) structures. A review of nanomedicines on the market and in clinical translation reveals that the vast majority is based on liposomes, polymeric micelles, and nanoparticles. The increasing presence of these novel nanomedicines raises the question what nanomedicines in the clinic right now really form nanoparticles, i.e., are improvements we see from nanomedicines structure-related or do they result from improved formulations? Do we even have sufficient data to address this question? The formation of nanocarriers is usually confirmed in vitro but little if any in vivo (let alone clinical) information is available. Given the large number of nanomedicines on the market and under clinical evaluation one clearly cannot expect to find a 'one size fits all' answer. Therefore, two case studies are discussed: the paclitaxel formulation Taxol® and its nanomedicine companions LEP-ETU (liposome), Genexol®-PM and NK105 (micelles), and Abraxane® (nanoparticle). Published pharmacokinetic data is utilized to find differences indicating nanocarrier delivery. The second case study involves structurally related camptothecin-polymer conjugates CRLX101 (nanoparticles) and XMT-1001 (prodrug). Structural differences are evaluated to discuss the different aggregation behavior. This opinion can only serve as first attempt to find a more general answer; clearly more data is needed from future studies. © 2014 Wiley Periodicals, Inc.

Aluminum stimulates uptake of non-transferrin bound iron and transferrin bound iron in human glial cells

International Nuclear Information System (INIS)

Kim, Yongbae; Olivi, Luisa; Cheong, Jae Hoon; Maertens, Alex; Bressler, Joseph P.

2007-01-01

Aluminum and other trivalent metals were shown to stimulate uptake of transferrin bound iron and nontransferrin bound iron in erytholeukemia and hepatoma cells. Because of the association between aluminum and Alzheimer's Disease, and findings of higher levels of iron in Alzheimer's disease brains, the effects of aluminum on iron homeostasis were examined in a human glial cell line. Aluminum stimulated dose- and time-dependent uptake of nontransferrin bound iron and iron bound to transferrin. A transporter was likely involved in the uptake of nontransferrin iron because uptake reached saturation, was temperature-dependent, and attenuated by inhibitors of protein synthesis. Interestingly, the effects of aluminum were not blocked by inhibitors of RNA synthesis. Aluminum also decreased the amount of iron bound to ferritin though it did not affect levels of divalent metal transporter 1. These results suggest that aluminum disrupts iron homeostasis in Brain by several mechanisms including the transferrin receptor, a nontransferrin iron transporter, and ferritin

Capacity Bounds for Parallel Optical Wireless Channels

KAUST Repository

Chaaban, Anas; Rezki, Zouheir; Alouini, Mohamed-Slim

2016-01-01

A system consisting of parallel optical wireless channels with a total average intensity constraint is studied. Capacity upper and lower bounds for this system are derived. Under perfect channel-state information at the transmitter (CSIT), the bounds have to be optimized with respect to the power allocation over the parallel channels. The optimization of the lower bound is non-convex, however, the KKT conditions can be used to find a list of possible solutions one of which is optimal. The optimal solution can then be found by an exhaustive search algorithm, which is computationally expensive. To overcome this, we propose low-complexity power allocation algorithms which are nearly optimal. The optimized capacity lower bound nearly coincides with the capacity at high SNR. Without CSIT, our capacity bounds lead to upper and lower bounds on the outage probability. The outage probability bounds meet at high SNR. The system with average and peak intensity constraints is also discussed.

Product differentiation under bounded rationality

NARCIS (Netherlands)

Vermeulen, B.; Poutré, La J.A.; Kok, de A.G.; Pyka, A.; Handa, H.; Ishibuchi, H.; Ong, Y.-S.; Tan, K.-C.

2015-01-01

We study product differentiation equilibria and dynamics on the Salop circle under bounded rationality. Due to bounded rationality, firms tend to agglomerate in pairs. Upon adding a second tier of component suppliers, downstream assemblers may escape pairwise horizontal agglomeration. Moreover, we

Massive Galileon positivity bounds

Science.gov (United States)

de Rham, Claudia; Melville, Scott; Tolley, Andrew J.; Zhou, Shuang-Yong

2017-09-01

The EFT coefficients in any gapped, scalar, Lorentz invariant field theory must satisfy positivity requirements if there is to exist a local, analytic Wilsonian UV completion. We apply these bounds to the tree level scattering amplitudes for a massive Galileon. The addition of a mass term, which does not spoil the non-renormalization theorem of the Galileon and preserves the Galileon symmetry at loop level, is necessary to satisfy the lowest order positivity bound. We further show that a careful choice of successively higher derivative corrections are necessary to satisfy the higher order positivity bounds. There is then no obstruction to a local UV completion from considerations of tree level 2-to-2 scattering alone. To demonstrate this we give an explicit example of such a UV completion.

Enhanced electron capture by fast heavy di-clusters exciting solids

International Nuclear Information System (INIS)

Cooney, P.J.; Faibis, A.; Kanter, E.P.; Koenig, W.; Maor, D.; Zabransky, B.J.

1985-01-01

The authors have studied the dependence of the charge-state-distributions of heavy-ion fragments resulting from the foil-induced dissociation of 4.2-MeV N 2 + ions on the thickness of the carbon target foil. The results were compared to those distributions measured for impact of 2.1-MeV N + projectiles. Whereas the charge-state distributions for atomic ion impact are already equilibrated in the thinnest targets used (2 μg/cm 2 ), those measured for molecular ion impact are strongly dependent on the target thickness, even for the thickest targets (100 + g/cm 2 ). The distributions for molecular-ion impact show a marked shift towards lower charge states, evidencing an enhanced electron capture probability over the case of monatomic ion impact. A quantitative model was developed to explain this phenomenon

New bounds on isotropic Lorentz violation

International Nuclear Information System (INIS)

Carone, Christopher D.; Sher, Marc; Vanderhaeghen, Marc

2006-01-01

Violations of Lorentz invariance that appear via operators of dimension four or less are completely parametrized in the Standard Model Extension (SME). In the pure photonic sector of the SME, there are 19 dimensionless, Lorentz-violating parameters. Eighteen of these have experimental upper bounds ranging between 10 -11 and 10 -32 ; the remaining parameter, k-tilde tr , is isotropic and has a much weaker bound of order 10 -4 . In this Brief Report, we point out that k-tilde tr gives a significant contribution to the anomalous magnetic moment of the electron and find a new upper bound of order 10 -8 . With reasonable assumptions, we further show that this bound may be improved to 10 -14 by considering the renormalization of other Lorentz-violating parameters that are more tightly constrained. Using similar renormalization arguments, we also estimate bounds on Lorentz-violating parameters in the pure gluonic sector of QCD

Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

Directory of Open Access Journals (Sweden)

Yang Yongkun

2012-10-01

Full Text Available Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs to encapsulate gold nanoparticles. The protein nanoparticles are formed upon self-assembly of a protein chain that is composed of a pentameric coiled-coil domain at the N-terminus and trimeric coiled-coil domain at the C-terminus. The self-assembling protein nanoparticles form a central cavity of about 10 nm in size, which is ideal for the encapsulation of gold nanoparticles with similar sizes. Results We have used SAPNs to encapsulate several commercially available gold nanoparticles. The hydrodynamic size and the surface coating of gold nanoparticles are two important factors influencing successful encapsulation by the SAPNs. Gold nanoparticles with a hydrodynamic size of less than 15 nm can successfully be encapsulated. Gold nanoparticles with citrate coating appear to have stronger interactions with the proteins, which can interfere with the formation of regular protein nanoparticles. Upon encapsulation gold nanoparticles with polymer coating interfere less strongly with the ability of the SAPNs to assemble into nanoparticles. Although the central cavity of the SAPNs carries an overall charge, the electrostatic interaction appears to be less critical for the efficient encapsulation of gold nanoparticles into the protein nanoparticles. Conclusions The SAPNs can be used to encapsulate gold nanoparticles. The SAPNs can be further functionalized by engineering functional peptides or proteins to either their N- or C-termini. Therefore encapsulation of gold

Tight Bounds for Distributed Functional Monitoring

DEFF Research Database (Denmark)

Woodruff, David P.; Zhang, Qin

2011-01-01

$, our bound resolves their main open question. Our lower bounds are based on new direct sum theorems for approximate majority, and yield significant improvements to problems in the data stream model, improving the bound for estimating $F_p, p > 2,$ in $t$ passes from $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{2/p......} t))$ to $\\tilde{\\Omega}(n^{1-2/p}/(\\eps^{4/p} t))$, giving the first bound for estimating $F_0$ in $t$ passes of $\\Omega(1/(\\eps^2 t))$ bits of space that does not use the gap-hamming problem, and showing a distribution for the gap-hamming problem with high external information cost or super...

Combining Alphas via Bounded Regression

Directory of Open Access Journals (Sweden)

Zura Kakushadze

2015-11-01

Full Text Available We give an explicit algorithm and source code for combining alpha streams via bounded regression. In practical applications, typically, there is insufficient history to compute a sample covariance matrix (SCM for a large number of alphas. To compute alpha allocation weights, one then resorts to (weighted regression over SCM principal components. Regression often produces alpha weights with insufficient diversification and/or skewed distribution against, e.g., turnover. This can be rectified by imposing bounds on alpha weights within the regression procedure. Bounded regression can also be applied to stock and other asset portfolio construction. We discuss illustrative examples.

Quasi-bound states in continuum

International Nuclear Information System (INIS)

Nakamura, Hiroaki; Hatano, Naomichi; Garmon, Sterling; Petrosky, Tomio

2007-08-01

We report the prediction of quasi-bound states (resonant states with very long lifetimes) that occur in the eigenvalue continuum of propagating states for a wide region of parameter space. These quasi-bound states are generated in a quantum wire with two channels and an adatom, when the energy bands of the two channels overlap. A would-be bound state that lays just below the upper energy band is slightly destabilized by the lower energy band and thereby becomes a resonant state with a very long lifetime (a second QBIC lays above the lower energy band). (author)

Controlled release of bupivacaine using hybrid thermoresponsive nanoparticles activated via photothermal heating.

Science.gov (United States)

Alejo, Teresa; Andreu, Vanesa; Mendoza, Gracia; Sebastian, Victor; Arruebo, Manuel

2018-08-01

Near-infrared (NIR) responsive nanoparticles are of great interest in the biomedical field as antennas for photothermal therapy and also as triggers for on-demand drug delivery. The present work reports the preparation of hollow gold nanoparticles (HGNPs) with plasmonic absorption in the NIR region covalently bound to a thermoresponsive polymeric shell that can be used as an on-demand drug delivery system for the release of analgesic drugs. The photothermal heating induced by the nanoparticles is able to produce the collapse of the polymeric shell thus generating the release of the local anesthetic bupivacaine in a spatiotemporally controlled way. Those HGNPs contain a 10 wt.% of polymer and present excellent reversible heating under NIR light excitation. Bupivacaine released at physiological temperature (37 °C) showed a pseudo-zero order release that could be spatiotemporally modified on-demand after applying several pulses of light/temperature above and below the lower critical solution temperature (LCST) of the polymeric shell. Furthermore, the nanomaterials obtained did not displayed detrimental effects on four mammalian cell lines at doses up to 0.2 mg/mL. From the results obtained it can be concluded than this type of hybrid thermoresponsive nanoparticle can be used as an externally activated on-demand drug delivery system. Copyright © 2018 Elsevier Inc. All rights reserved.

WE-H-207A-09: Theoretical Limits to Molecular Biomarker Detection Using Magnetic Nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Weaver, J [Dartmouth-Hitchcock Medical Center, Lebanon, NH (United States); Geisel School of Medicine, Dartmouth College, Hanover, NH (United States)

2016-06-15

Purpose: Estimate the limits of molecular biomarker detection using magnetic nanoparticle methods like in vivo ELISA. Methods: Magnetic nanoparticles in an alternating magnetic field produce a magnetization that can be detected at exceedingly low levels because the signal at the harmonic frequencies is uniquely produced by the nanoparticles. Because the magnetization can also be used to characterize the nanoparticle rotational freedom, the bound state can be found. If the nanoparticles are coated with molecules that bind the desired biomarker, the rotational freedom reflects the biomarker concentration. The irreducible noise limit is the thermal noise or Johnson noise of the tissue and the contrast that can be measured must be larger than that limit. The contrast produced is a function of the applied field and depends strongly on nanoparticle volume. We have estimated the contrast using a Langevin function of a single composite variable to approximate the full stochastic Langevin equation for nanoparticle dynamics. Results: The thermal noise for a bandwidth reasonable for spectroscopy suggests mid zeptomolar (10–21) to low attomolar (10–18) concentrations can be measured in a volume that is 10cm in scale. The suggested sensitivity is far below the physiologically concentrations of almost all critical biomarkers including cytokines (picomolar), hormones (nanomolar) and heat shock proteins. Conclusion: The sensitivity of in vivo ELISA concentration measurements should be sufficient to measure physiological concentrations of critical biomarkers like cytokines in vivo. Further the sensitivity should be sufficient to measure concentrations of other biomarkers that are six to eight orders of magnitude lower in concentration than immune signaling molecules like cytokines. NIH - 1U54CA151662-01 Department of Radiology.

Chemisorption of iodine-125 to gold nanoparticles allows for real-time quantitation and potential use in nanomedicine

Energy Technology Data Exchange (ETDEWEB)

Walsh, Adrian A, E-mail: a.walsh@nanobiosols.com [Liverpool Science Park, Nano Biosols Ltd (United Kingdom)

2017-04-15

Gold nanoparticles have been available for many years as a research tool in the life sciences due to their electron density and optical properties. New applications are continually being developed, particularly in nanomedicine. One drawback is the need for an easy, real-time quantitation method for gold nanoparticles so that the effects observed in in vitro cell toxicity assays and cell uptake studies can be interpreted quantitatively in terms of nanoparticle loading. One potential method of quantifying gold nanoparticles in real time is by chemisorption of iodine-125, a gamma emitter, to the nanoparticles. This paper revisits the labelling of gold nanoparticles with iodine-125, first described 30 years ago and never fully exploited since. We explore the chemical properties and usefulness in quantifying bio-functionalised gold nanoparticle binding in a quick and simple manner. The gold particles were labelled specifically and quantitatively simply by mixing the two items. The nature of the labelling is chemisorption and is robust, remaining bound over several weeks in a variety of cell culture media. Chemisorption was confirmed as potassium iodide can remove the label whereas sodium chloride and many other buffers had no effect. Particles precoated in polymers or proteins can be labelled just as efficiently allowing for post-labelling experiments in situ rather than using radioactive gold atoms in the production process. We also demonstrate that interparticle exchange of I-125 between different size particles does not appear to take place confirming the affinity of the binding.

Chemisorption of iodine-125 to gold nanoparticles allows for real-time quantitation and potential use in nanomedicine

Science.gov (United States)

Walsh, Adrian A.

2017-04-01

Gold nanoparticles have been available for many years as a research tool in the life sciences due to their electron density and optical properties. New applications are continually being developed, particularly in nanomedicine. One drawback is the need for an easy, real-time quantitation method for gold nanoparticles so that the effects observed in in vitro cell toxicity assays and cell uptake studies can be interpreted quantitatively in terms of nanoparticle loading. One potential method of quantifying gold nanoparticles in real time is by chemisorption of iodine-125, a gamma emitter, to the nanoparticles. This paper revisits the labelling of gold nanoparticles with iodine-125, first described 30 years ago and never fully exploited since. We explore the chemical properties and usefulness in quantifying bio-functionalised gold nanoparticle binding in a quick and simple manner. The gold particles were labelled specifically and quantitatively simply by mixing the two items. The nature of the labelling is chemisorption and is robust, remaining bound over several weeks in a variety of cell culture media. Chemisorption was confirmed as potassium iodide can remove the label whereas sodium chloride and many other buffers had no effect. Particles precoated in polymers or proteins can be labelled just as efficiently allowing for post-labelling experiments in situ rather than using radioactive gold atoms in the production process. We also demonstrate that interparticle exchange of I-125 between different size particles does not appear to take place confirming the affinity of the binding.

Chemisorption of iodine-125 to gold nanoparticles allows for real-time quantitation and potential use in nanomedicine

International Nuclear Information System (INIS)

Walsh, Adrian A

2017-01-01

Gold nanoparticles have been available for many years as a research tool in the life sciences due to their electron density and optical properties. New applications are continually being developed, particularly in nanomedicine. One drawback is the need for an easy, real-time quantitation method for gold nanoparticles so that the effects observed in in vitro cell toxicity assays and cell uptake studies can be interpreted quantitatively in terms of nanoparticle loading. One potential method of quantifying gold nanoparticles in real time is by chemisorption of iodine-125, a gamma emitter, to the nanoparticles. This paper revisits the labelling of gold nanoparticles with iodine-125, first described 30 years ago and never fully exploited since. We explore the chemical properties and usefulness in quantifying bio-functionalised gold nanoparticle binding in a quick and simple manner. The gold particles were labelled specifically and quantitatively simply by mixing the two items. The nature of the labelling is chemisorption and is robust, remaining bound over several weeks in a variety of cell culture media. Chemisorption was confirmed as potassium iodide can remove the label whereas sodium chloride and many other buffers had no effect. Particles precoated in polymers or proteins can be labelled just as efficiently allowing for post-labelling experiments in situ rather than using radioactive gold atoms in the production process. We also demonstrate that interparticle exchange of I-125 between different size particles does not appear to take place confirming the affinity of the binding.

A randomized phase II study of carboplatin with weekly or every-3-week nanoparticle albumin-bound paclitaxel (abraxane) in patients with extensive-stage small cell lung cancer.

Science.gov (United States)

Grilley-Olson, Juneko E; Keedy, Vicki L; Sandler, Alan; Moore, Dominic T; Socinski, Mark A; Stinchcombe, Thomas E

2015-02-01

Platinum plus etoposide is the standard therapy for extensive-stage small cell lung cancer (ES-SCLC) and is associated with significant myelosuppression. We hypothesized that the combination of carboplatin and nanoparticle albumin-bound paclitaxel (nab-paclitaxel) would be better tolerated. We investigated carboplatin with nab-paclitaxel on every-3-week and weekly schedules. This noncomparative randomized phase II trial used a two-stage design. The primary objective was objective response rate, and secondary objectives were progression-free survival, overall survival, and toxicity. Patients with ES-SCLC and an Eastern Cooperative Oncology Group performance status ≤2 and no prior chemotherapy were randomized in a 1:1 ratio to arm A (carboplatin area under the curve [AUC] of 6 on day 1 and nab-paclitaxel of 300 mg/m(2) on day 1 every 3 weeks) or arm B (carboplatin AUC of 6 on day 1 and nab-paclitaxel 100 mg/m(2) on days 1, 8, and 15 every 21 days). Response was assessed after every two cycles. Patients required frequent dose reductions, treatment delays, and omission of the weekly therapy. The trial was closed because of slow accrual. Carboplatin and nab-paclitaxel demonstrated activity in ES-SCLC but required frequent dose adjustments. ©AlphaMed Press; the data published online to support this summary is the property of the authors.

A novel method for the synthesis of monodisperse gold-coated silica nanoparticles

International Nuclear Information System (INIS)

English, Michael D.; Waclawik, Eric R.

2012-01-01

Monodisperse silica nanoparticles were synthesised by the well-known Stober protocol, then dispersed in acetonitrile (ACN) and subsequently added to a bisacetonitrile gold(I) coordination complex ([Au(MeCN) 2 ] + ) in ACN. The silica hydroxyl groups were deprotonated in the presence of ACN, generating a formal negative charge on the siloxy groups. This allowed the [Au(MeCN) 2 ] + complex to undergo ligand exchange with the silica nanoparticles and form a surface coordination complex with reduction to metallic gold (Au 0 ) proceeding by an inner sphere mechanism. The residual [Au(MeCN) 2 ] + complex was allowed to react with water, disproportionating into Au 0 and Au(III), respectively, with the Au 0 adding to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be suitable for the conventional reduction of Au(III) to Au 0 by ascorbic acid (ASC). This process generated a thin and uniform gold coating on the silica nanoparticles. The silica NPs batches synthesised were in a size range from 45 to 460 nm. Of these silica NP batches, the size range from 400 to 480 nm were used for the gold-coating experiments.

Bounded Rationality and Budgeting

OpenAIRE

Ibrahim, Mukdad

2016-01-01

This article discusses the theory of bounded rationality which had been introduced by Herbert Simon in the 1950s. Simon introduced the notion of bounded rationality stating that while decision-makers strive for rationality, they are limited by the effect of the environment, their information process capacity and by the constraints on their information storage and retrieval capabilities. Moreover, this article tries to specifically blend this notion into budgeting, using the foundations of inc...

Fuzzy upper bounds and their applications

Energy Technology Data Exchange (ETDEWEB)

Soleimani-damaneh, M. [Department of Mathematics, Faculty of Mathematical Science and Computer Engineering, Teacher Training University, 599 Taleghani Avenue, Tehran 15618 (Iran, Islamic Republic of)], E-mail: soleimani_d@yahoo.com

2008-04-15

This paper considers the concept of fuzzy upper bounds and provides some relevant applications. Considering a fuzzy DEA model, the existence of a fuzzy upper bound for the objective function of the model is shown and an effective approach to solve that model is introduced. Some dual interpretations are provided, which are useful for practical purposes. Applications of the concept of fuzzy upper bounds in two physical problems are pointed out.

A Lagrangian lower bound for the container transshipment problem at a railway hub for a fast branch-and-bound algorithm

OpenAIRE

M Barketau; H Kopfer; E Pesch

2013-01-01

In this paper, we consider the container transshipment problem at a railway hub. A simple lower bound known for this problem will be improved by a new Lagrangian relaxation lower bound. Computational tests show that this lower bound outperforms the simple one and decreases substantially the run time of the branch-and-bound algorithm.

Human serum albumin nanoparticles modified with apolipoprotein A-I cross the blood-brain barrier and enter the rodent brain.

Science.gov (United States)

Zensi, Anja; Begley, David; Pontikis, Charles; Legros, Celine; Mihoreanu, Larisa; Büchel, Claudia; Kreuter, Jörg

2010-12-01

Nanoparticles made of human serum albumin (HSA) and modified with apolipoproteins have previously been shown to transport drugs, which normally do not enter the brain, across the blood-brain barrier (BBB). However the precise mechanism by which nanoparticles with different apolipoproteins on their surface can target to the brain, as yet, has not been totally elucidated. In the present study, HSA nanoparticles with covalently bound apolipoprotein A-I (Apo A-I) as a targetor for brain capillary endothelial cells were injected intravenously into SV 129 mice and Wistar rats. The rodents were sacrificed after 15 or 30 min, and their brains were examined by transmission electron microscopy. Apo A-I nanoparticles could be found inside the endothelial cells of brain capillaries as well as within parenchymal brain tissue of both, mice and rats, whereas control particles without Apo A-I on their surface did not cross the BBB during our experiments. The maintenance of tight junction integrity and barrier function during treatment with nanoparticles was demonstrated by perfusion with a fixative containing lanthanum nitrate as an electron dense marker for the permeability of tight junctions.

Improved Range Searching Lower Bounds

DEFF Research Database (Denmark)

Larsen, Kasper Green; Nguyen, Huy L.

2012-01-01

by constructing a hard input set and query set, and then invoking Chazelle and Rosenberg's [CGTA'96] general theorem on the complexity of navigation in the pointer machine. For the group model, we show that input sets and query sets that are hard for range reporting in the pointer machine (i.e. by Chazelle...... and Rosenberg's theorem), are also hard for dynamic range searching in the group model. This theorem allows us to reuse decades of research on range reporting lower bounds to immediately obtain a range of new group model lower bounds. Amongst others, this includes an improved lower bound for the fundamental...

Green synthesis and characterization of silver nanoparticles using alcoholic flower extract of Nyctanthes arbortristis and in vitro investigation of their antibacterial and cytotoxic activities

International Nuclear Information System (INIS)

Gogoi, Nayanmoni; Babu, Punuri Jayasekhar; Mahanta, Chandan; Bora, Utpal

2015-01-01

Here we report the synthesis of silver nanoparticles using ethanolic flower extract of Nyctanthes arbortristis, UVvisible spectra and TEM indicated the successful formation of silver nanoparticles. Crystalline nature of the silver nanoparticles was confirmed by X-ray diffraction. Fourier Transform Infra-Red Spectroscopy analysis established the capping of the synthesized silver nanoparticles with phytochemicals naturally occurring in the ethanolic flower extract of N. arbortristis. The synthesized silver nanoparticles showed antibacterial activity against the pathogenic strain of Escherichia coli MTCC 443. Furthermore, cytotoxicity of the silver nanoparticles was tested on mouse fibroblastic cell line (L929) and found to be non-toxic, which thus proved their biocompatibility. Antibacterial activity and cytotoxicity assay carried out in this study open up an important perspective of the synthesized silver nanoparticles. - Highlights: • The present study depicts the green synthesis of AgNPs using Nyctanthes arbortristis. • AuNPs found to be biocompatible and can be used for biomedical applications. • The FTIR, TGA and DTA results showed that AgNPs are bounded by organic coating. • The synthesized AgNPs showed antibacterial activity on E. Coli MTCC 443. • We investigated the antioxidant activity for both EFE and AgNPs

Two-phonon bound states in imperfect crystals

International Nuclear Information System (INIS)

Behera, S.N.; Samsur, Sk.

1980-01-01

The question of the occurrence of two-phonon bound states in imperfect crystals is investigated. It is shown that the anharmonicity mediated two-phonon bound state which is present in perfect crystals gets modified due to the presence of impurities. Moreover, the possibility of the occurrence of a purely impurity mediated two-phonon bound state is demonstrated. The bound state frequencies are calculated using the simple Einstein oscillator model for the host phonons. The two-phonon density of states for the imperfect crystal thus obtained has peaks at the combination and difference frequencies of two host phonons besides the peaks at the bound state frequencies. For a perfect crystal the theory predicts a single peak at the two-phonon bound state frequency in conformity with experimental observations and other theoretical calculations. Experimental data on the two-phonon infrared absorption and Raman scattering from mixed crystals of Gasub(1-c)Alsub(c)P and Gesub(1-c)Sisub(c) are analysed to provide evidence in support of impurity-mediated two-phonon bound states. The relevance of the zero frequency (difference spectrum) peak to the central peak, observed in structural phase transitions, is conjectured. (author)

On semidefinite programming bounds for graph bandwidth

NARCIS (Netherlands)

de Klerk, E.; Nagy, M.; Sotirov, R.

2013-01-01

In this paper, we propose two new lower bounds on graph bandwidth and cyclic bandwidth based on semidefinite programming (SDP) relaxations of the quadratic assignment problem. We compare the new bounds with two other SDP bounds reported in [A. Blum, G. Konjevod, R. Ravi, and S. Vempala,

Bounded elements in Locally C*-algebras

International Nuclear Information System (INIS)

El Harti, Rachid

2001-09-01

In order to get more useful information about Locally C*-algebras, we introduce in this paper the notion of bounded elements. First, we study the connection between bounded elements and spectrally bounded elements. Some structural results of Locally C*-algebras are established in Theorems 1 , 2 and 3. As an immediate consequence of Theorem 3, we give a characterization of the connected component of the identity in the group of unitary elements for a Locally C*-algebra. (author)

Covariant entropy bound and loop quantum cosmology

International Nuclear Information System (INIS)

Ashtekar, Abhay; Wilson-Ewing, Edward

2008-01-01

We examine Bousso's covariant entropy bound conjecture in the context of radiation filled, spatially flat, Friedmann-Robertson-Walker models. The bound is violated near the big bang. However, the hope has been that quantum gravity effects would intervene and protect it. Loop quantum cosmology provides a near ideal setting for investigating this issue. For, on the one hand, quantum geometry effects resolve the singularity and, on the other hand, the wave function is sharply peaked at a quantum corrected but smooth geometry, which can supply the structure needed to test the bound. We find that the bound is respected. We suggest that the bound need not be an essential ingredient for a quantum gravity theory but may emerge from it under suitable circumstances.

Degenerate quantum codes and the quantum Hamming bound

International Nuclear Information System (INIS)

Sarvepalli, Pradeep; Klappenecker, Andreas

2010-01-01

The parameters of a nondegenerate quantum code must obey the Hamming bound. An important open problem in quantum coding theory is whether the parameters of a degenerate quantum code can violate this bound for nondegenerate quantum codes. In this article we show that Calderbank-Shor-Steane (CSS) codes, over a prime power alphabet q≥5, cannot beat the quantum Hamming bound. We prove a quantum version of the Griesmer bound for the CSS codes, which allows us to strengthen the Rains' bound that an [[n,k,d

Some Improved Nonperturbative Bounds for Fermionic Expansions

Energy Technology Data Exchange (ETDEWEB)

Lohmann, Martin, E-mail: marlohmann@gmail.com [Universita di Roma Tre, Dipartimento di Matematica (Italy)

2016-06-15

We reconsider the Gram-Hadamard bound as it is used in constructive quantum field theory and many body physics to prove convergence of Fermionic perturbative expansions. Our approach uses a recursion for the amplitudes of the expansion, discovered in a model problem by Djokic (2013). It explains the standard way to bound the expansion from a new point of view, and for some of the amplitudes provides new bounds, which avoid the use of Fourier transform, and are therefore superior to the standard bounds for models like the cold interacting Fermi gas.

Sharp Bounds for Symmetric and Asymmetric Diophantine Approximation

Institute of Scientific and Technical Information of China (English)

Cornelis KRAAIKAMP; Ionica SMEETS

2011-01-01

In 2004,Tong found bounds for the approximation quality of a regular continued fraction convergent to a rational number,expressed in bounds for both the previous and next approximation.The authors sharpen his results with a geometric method and give both sharp upper and lower bounds.The asymptotic frequencies that these bounds occur are also calculated.

SHARP ENTRYWISE PERTURBATION BOUNDS FOR MARKOV CHAINS.

Science.gov (United States)

Thiede, Erik; VAN Koten, Brian; Weare, Jonathan

For many Markov chains of practical interest, the invariant distribution is extremely sensitive to perturbations of some entries of the transition matrix, but insensitive to others; we give an example of such a chain, motivated by a problem in computational statistical physics. We have derived perturbation bounds on the relative error of the invariant distribution that reveal these variations in sensitivity. Our bounds are sharp, we do not impose any structural assumptions on the transition matrix or on the perturbation, and computing the bounds has the same complexity as computing the invariant distribution or computing other bounds in the literature. Moreover, our bounds have a simple interpretation in terms of hitting times, which can be used to draw intuitive but rigorous conclusions about the sensitivity of a chain to various types of perturbations.

21 CFR 862.1640 - Protein-bound iodine test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Protein-bound iodine test system. 862.1640 Section... Systems § 862.1640 Protein-bound iodine test system. (a) Identification. A protein-bound iodine test system is a device intended to measure protein-bound iodine in serum. Measurements of protein-bound...

Relativistic bound state wave functions

International Nuclear Information System (INIS)

Micu, L.

2005-01-01

A particular method of writing the bound state wave functions in relativistic form is applied to the solutions of the Dirac equation with confining potentials in order to obtain a relativistic description of a quark antiquark bound system representing a given meson. Concerning the role of the effective constituent in the present approach we first observe that without this additional constituent we couldn't expand the bound state wave function in terms of products of free states. Indeed, we notice that if the wave function depends on the relative coordinates only, all the expansion coefficients would be infinite. Secondly we remark that the effective constituent enabled us to give a Lorentz covariant meaning to the potential energy of the bound system which is now seen as the 4th component of a 4-momentum. On the other side, by relating the effective constituent to the quantum fluctuations of the background field which generate the binding, we provided a justification for the existence of some spatial degrees of freedom accompanying the interaction potential. These ones, which are quite unusual in quantum mechanics, in our model are the natural consequence of the the independence of the quarks and can be seen as the effect of the imperfect cancellation of the vector momenta during the quantum fluctuations. Related with all these we remark that the adequate representation for the relativistic description of a bound system is the momentum representation, because of the transparent and easy way of writing the conservation laws and the transformation properties of the wave functions. The only condition to be fulfilled is to find a suitable way to take into account the potential energy of the bound system. A particular feature of the present approach is that the confining forces are due to a kind of glue where both quarks are embedded. This recalls other bound state models where the wave function is factorized in terms of constituent wave functions and the confinement is

Bounds on poloidal kinetic energy in plane layer convection

Science.gov (United States)

Tilgner, A.

2017-12-01

A numerical method is presented that conveniently computes upper bounds on heat transport and poloidal energy in plane layer convection for infinite and finite Prandtl numbers. The bounds obtained for the heat transport coincide with earlier results. These bounds imply upper bounds for the poloidal energy, which follow directly from the definitions of dissipation and energy. The same constraints used for computing upper bounds on the heat transport lead to improved bounds for the poloidal energy.

Persistence-Based Branch Misprediction Bounds for WCET Analysis

DEFF Research Database (Denmark)

Puffitsch, Wolfgang

2015-01-01

Branch prediction is an important feature of pipelined processors to achieve high performance. However, it can lead to overly pessimistic worst-case execution time (WCET) bounds when being modeled too conservatively. This paper presents bounds on the number of branch mispredictions for local...... dynamic branch predictors. To handle interferences between branch instructions we use the notion of persistence, a concept that is also found in cache analyses. The bounds apply to branches in general, not only to branches that close a loop. Furthermore, the bounds can be easily integrated into integer...... linear programming formulations of the WCET problem. An evaluation on a number of benchmarks shows that with these bounds, dynamic branch prediction does not necessarily lead to higher WCET bounds than static prediction schemes....

Positivity bounds on double parton distributions

International Nuclear Information System (INIS)

Diehl, Markus; Kasemets, Tomas

2013-03-01

Double hard scattering in proton-proton collisions is described in terms of double parton distributions. We derive bounds on these distributions that follow from their interpretation as probability densities, taking into account all possible spin correlations between two partons in an unpolarized proton. These bounds constrain the size of the polarized distributions and can for instance be used to set upper limits on the effects of spin correlations in double hard scattering. We show that the bounds are stable under leading-order DGLAP evolution to higher scales.

Comparison of Lasserre's Measure-based Bounds for Polynomial Optimization to Bounds Obtained by Simulated Annealing

NARCIS (Netherlands)

de Klerk, Etienne; Laurent, Monique

We consider the problem of minimizing a continuous function f over a compact set K. We compare the hierarchy of upper bounds proposed by Lasserre in [SIAM J. Optim. 21(3) (2011), pp. 864-885] to bounds that may be obtained from simulated annealing. We show that, when f is a polynomial and K a convex

Anchoring of ulex europaeus agglutinin to chitosan nanoparticles-in-microparticles and their in vitro binding activity to bovine submaxillary gland mucin.

Science.gov (United States)

Li, Feng-Qian; Fei, Yi-Bo; Chen, Xu; Qin, Xian-Ju; Liu, Ji-Yong; Zhu, Quan-Gang; Hu, Jin-Hong

2009-10-01

Focused on the natural biodegradable material of chitosan (CS), this investigation concerned its spray-dried nanoparticles-in-microparticles (NiMPs) modified with ulex europaeus agglutinin (UEA). Chitosan nanoparticles were obtained by ionotropic gelation process with pentasodium tripolyphosphate as gelatinizer. Then UEA lectin was bound onto the CS nanoparticles activated by glutaraldehyde. The conjugated spherical UEA-CS-NiMPs, prepared by spray drying method, exhibited 12-85% coupling efficiency of UEA depending upon the amount of activator glutaraldehyde. And the UEA-grafted particles showed additional higher binding tendency with bovine submaxillary gland mucin as compared to the plain chitosan microparticles. Furthermore, the activity and intrinsic fucose-specificity of UEA were still maintained after the covalent modification. It is thus evident that the UEA anchored CS-NiMPs might be used as a potential drug delivery system targeted to the specific regions of gastrointestinal tract.

Universal bounds in even-spin CFTs

Energy Technology Data Exchange (ETDEWEB)

Qualls, Joshua D. [Department of Physics, National Taiwan University,Taipei, Taiwan (China)

2015-12-01

We prove using invariance under the modular S− and ST−transformations that every unitary two-dimensional conformal field theory (CFT) having only even-spin primary operators (with no extended chiral algebra and with right- and left-central charges c,c̃>1) contains a primary operator with dimension Δ{sub 1} satisfying 0<Δ{sub 1}<((c+c̃)/24)+0.09280…. After deriving both analytical and numerical bounds, we discuss how to extend our methods to bound higher conformal dimensions before deriving lower and upper bounds on the number of primary operators in a given energy range. Using the AdS{sub 3}/CFT{sub 2} dictionary, the bound on Δ{sub 1} proves the lightest massive excitation in appropriate theories of 3D matter and gravity with cosmological constant Λ<0 can be no heavier than 1/8G{sub N}+O(√(−Λ)); the bounds on the number of operators are related via AdS/CFT to the entropy of states in the dual gravitational theory. In the flat-space approximation, the limiting mass is exactly that of the lightest BTZ black hole.

Cancer therapy with drug loaded magnetic nanoparticles-magnetic drug targeting

International Nuclear Information System (INIS)

Alexiou, Christoph; Tietze, Rainer; Schreiber, Eveline; Jurgons, Roland; Richter, Heike; Trahms, Lutz; Rahn, Helene; Odenbach, Stefan; Lyer, Stefan

2011-01-01

The aim of magnetic drug targeting (MDT) in cancer therapy is to concentrate chemotherapeutics to a tumor region while simultaneously the overall dose is reduced. This can be achieved with coated superparamagnetic nanoparticles bound to a chemotherapeutic agent. These particles are applied intra arterially close to the tumor region and focused to the tumor by a strong external magnetic field. The interaction of the particles with the field gradient leads to an accumulation in the region of interest (i.e. tumor). The particle enrichment and thereby the drug-load in the tumor during MDT has been proven by several analytical and imaging methods. Moreover, in pilot studies we investigated in an experimental in vivo tumor model the effectiveness of this approach. Complete tumor regressions without any negative side effects could be observed. - Research Highlights: →Iron oxide nanoparticles can be enriched in tumors by external magnetic fields. → Histology evidences the intravasation of particles enter the intracellular space. → Non-invasive imaging techniques can display the spatial arrangement of particles. → HPLC-analysis show outstanding drug enrichment in tumors after MDT.

Cancer therapy with drug loaded magnetic nanoparticles-magnetic drug targeting

Energy Technology Data Exchange (ETDEWEB)

Alexiou, Christoph, E-mail: c.alexiou@web.d [Department of Oto-rhino-laryngology, Head and Neck Surgery, University Hospital Erlangen, Section for Experimental Oncology and Nanomedicine at the Else Kroener-Fresenius-Stiftung-Professorship (Germany); Tietze, Rainer; Schreiber, Eveline [Department of Oto-rhino-laryngology, Head and Neck Surgery, University Hospital Erlangen, Section for Experimental Oncology and Nanomedicine at the Else Kroener-Fresenius-Stiftung-Professorship (Germany); Jurgons, Roland [Franz Penzoldt Center, University Hospital Erlangen (Germany); Richter, Heike; Trahms, Lutz [PTB Berlin (Germany); Rahn, Helene; Odenbach, Stefan [TU Dresden, Chair of Magnetofluiddynamics, 01062 Dresden (Germany); Lyer, Stefan [Department of Oto-rhino-laryngology, Head and Neck Surgery, University Hospital Erlangen, Section for Experimental Oncology and Nanomedicine at the Else Kroener-Fresenius-Stiftung-Professorship (Germany)

2011-05-15

The aim of magnetic drug targeting (MDT) in cancer therapy is to concentrate chemotherapeutics to a tumor region while simultaneously the overall dose is reduced. This can be achieved with coated superparamagnetic nanoparticles bound to a chemotherapeutic agent. These particles are applied intra arterially close to the tumor region and focused to the tumor by a strong external magnetic field. The interaction of the particles with the field gradient leads to an accumulation in the region of interest (i.e. tumor). The particle enrichment and thereby the drug-load in the tumor during MDT has been proven by several analytical and imaging methods. Moreover, in pilot studies we investigated in an experimental in vivo tumor model the effectiveness of this approach. Complete tumor regressions without any negative side effects could be observed. - Research Highlights: Iron oxide nanoparticles can be enriched in tumors by external magnetic fields. Histology evidences the intravasation of particles enter the intracellular space. Non-invasive imaging techniques can display the spatial arrangement of particles. HPLC-analysis show outstanding drug enrichment in tumors after MDT.

Nanoparticle based-immunotherapy against allergy.

Science.gov (United States)

Gamazo, Carlos; Gastaminza, Gabriel; Ferrer, Marta; Sanz, María L; Irache, Juan M

2014-01-01

Allergic diseases are one of the most prevalent diseases, reaching epidemic proportions in developed countries. An allergic reaction occurs after contact with an environmental protein, such as inhalants allergens (pollen, animal dander, house dust mites), or food proteins. This response is known as part of the type 2 immunity that is counterbalanced by Type 1 immunity and Tregs. Widely used allergen-specific immunotherapy (IT) is a long term treatment to induce such switch from Th2 to Th1 response. However, conventional IT requires multiple allergen injections over a long period of time and is not free of risk of producing allergic reactions. As a consequence, new safer and faster immunotherapeutic methods are required. This review deals with allergen IT using nanoparticles as allergen delivery system that will allow a different way of administration, reduce dose and diminish allergen exposure to IgE bound to mast cells or basophils.

Liposome encapsulation of fluorescent nanoparticles: Quantum dots and silica nanoparticles

International Nuclear Information System (INIS)

Chen, C.-S.; Yao Jie; Durst, Richard A.

2006-01-01

Quantum dots (QDs) and silica nanoparticles (SNs) are relatively new classes of fluorescent probes that overcome the limitations encountered by organic fluorophores in bioassay and biological imaging applications. We encapsulated QDs and SNs in liposomes and separated nanoparticle-loaded liposomes from unencapsulated nanoparticles by size exclusion chromatography. Fluorescence correlation spectroscopy was used to measure the average number of nanoparticles inside each liposome. Results indicated that nanoparticle-loaded liposomes were formed and separated from unencapsulated nanoparticles by using a Sepharose gel. As expected, fluorescence self-quenching of nanoparticles inside liposomes was not observed. Each liposome encapsulated an average of three QDs. These studies demonstrated that nanoparticles could be successfully encapsulated into liposomes and provided a methodology to quantify the number of nanoparticles inside each liposome by fluorescence correlation spectroscopy

Lower bounds for the minimum distance of algebraic geometry codes

DEFF Research Database (Denmark)

Beelen, Peter

, such as the Goppa bound, the Feng-Rao bound and the Kirfel-Pellikaan bound. I will finish my talk by giving several examples. Especially for two-point codes, the generalized order bound is fairly easy to compute. As an illustration, I will indicate how a lower bound can be obtained for the minimum distance of some...... description of these codes in terms of order domains has been found. In my talk I will indicate how one can use the ideas behind the order bound to obtain a lower bound for the minimum distance of any AG-code. After this I will compare this generalized order bound with other known lower bounds...

Absolute Lower Bound on the Bounce Action

Science.gov (United States)

Sato, Ryosuke; Takimoto, Masahiro

2018-03-01

The decay rate of a false vacuum is determined by the minimal action solution of the tunneling field: bounce. In this Letter, we focus on models with scalar fields which have a canonical kinetic term in N (>2 ) dimensional Euclidean space, and derive an absolute lower bound on the bounce action. In the case of four-dimensional space, we show the bounce action is generically larger than 24 /λcr, where λcr≡max [-4 V (ϕ )/|ϕ |4] with the false vacuum being at ϕ =0 and V (0 )=0 . We derive this bound on the bounce action without solving the equation of motion explicitly. Our bound is derived by a quite simple discussion, and it provides useful information even if it is difficult to obtain the explicit form of the bounce solution. Our bound offers a sufficient condition for the stability of a false vacuum, and it is useful as a quick check on the vacuum stability for given models. Our bound can be applied to a broad class of scalar potential with any number of scalar fields. We also discuss a necessary condition for the bounce action taking a value close to this lower bound.

Evacuation of Bed-bound Patients-STEPS Simulations

DEFF Research Database (Denmark)

Madsen, Anne; Dederichs, Anne Simone

2016-01-01

Fires in hospitals occur, and evacuation of bed-bound patients might be necessary in case of emergency. The current study concerns the evacuation of bed-bound patients from a fire section in a hospital using hospital porters. The simulations are performed using the STEPS program. The aim...... of the study is to investigate the evacuation time of bed-bound hospital patients using different walking speeds from the literature, and the influence of the number of hospital porters on the total evacuation times of bed-bound patients. Different scenarios were carried out with varying staff......-to-patient ratios that simulate the horizontal evacuation of 40 bed-bound patients into a different fire section. It was found that the staff-to-patient-ratio affects the total evacuation times. However, the total evacuation times do not decrease linearly and a saturation effect is seen at a staff-to-patient ratio...

Bounds in the location-allocation problem

DEFF Research Database (Denmark)

Juel, Henrik

1981-01-01

Develops a family of stronger lower bounds on the objective function value of the location-allocation problem. Solution methods proposed to solve problems in location-allocation; Efforts to develop a more efficient bound solution procedure; Determination of the locations of the sources....

No-arbitrage bounds for financial scenarios

DEFF Research Database (Denmark)

Geyer, Alois; Hanke, Michael; Weissensteiner, Alex

2014-01-01

We derive no-arbitrage bounds for expected excess returns to generate scenarios used in financial applications. The bounds allow to distinguish three regions: one where arbitrage opportunities will never exist, a second where arbitrage may be present, and a third, where arbitrage opportunities...

Architecture-independent power bound for vibration energy harvesters

International Nuclear Information System (INIS)

Halvorsen, E; Le, C P; Mitcheson, P D; Yeatman, E M

2013-01-01

The maximum output power of energy harvesters driven by harmonic vibrations is well known for a range of specific harvester architectures. An architecture-independent bound based on the mechanical input-power also exists and gives a strict limit on achievable power with one mechanical degree of freedom, but is a least upper bound only for lossless devices. We report a new theoretical bound on the output power of vibration energy harvesters that includes parasitic, linear mechanical damping while still being architecture independent. This bound greatly improves the previous bound at moderate force amplitudes and is compared to the performance of established harvester architectures which are shown to agree with it in limiting cases. The bound is a hard limit on achievable power with one mechanical degree of freedom and can not be circumvented by transducer or power-electronic-interface design

Uniform bounds for Black--Scholes implied volatility

OpenAIRE

Tehranchi, Michael R.

2015-01-01

In this note, Black--Scholes implied volatility is expressed in terms of various optimisation problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulae for implied volatility at extreme strikes and/or maturities.

Simulation bounds for system availability

International Nuclear Information System (INIS)

Tietjen, G.L.; Waller, R.A.

1976-01-01

System availability is a dominant factor in the practicality of nuclear power electrical generating plants. A proposed model for obtaining either lower bounds or interval estimates on availability uses observed data on ''n'' failure-to-repair cycles of the system to estimate the parameters in the time-to-failure and time-to-repair models. These estimates are then used in simulating failure/repair cycles of the system. The availability estimate is obtained for each of 5000 samples of ''n'' failure/repair cycles to form a distribution of estimates. Specific percentile points of those simulated distributions are selected as lower simulation bounds or simulation interval bounds for the system availability. The method is illustrated with operational data from two nuclear plants for which an exponential time-to-failure and a lognormal time-to-repair are assumed

Sulfur ligand mediated electrochemistry of gold surfaces and nanoparticles: what, how, and why

DEFF Research Database (Denmark)

Chi, Qijin; Ford, Michael J.; Halder, Arnab

2017-01-01

Gold surfaces are widely used in electrochemistry whilst gold nanoparticles have very many uses, with both the surfaces and the particles often being protected by sulfur-bound organic ligands. The ligands not only provide chemical stability but also directly participate in many desired processes....... This review considers the diversity of known atomic structures for gold-sulfur interfaces, how these structures facilitate a diversity of mechanisms in electrochemical applications, and why this is possible based on recent advances in the basic understanding of the electronic structure of gold-sulfur bonds...

Understanding nanoparticle-mediated nucleation pathways of anisotropic nanoparticles

Science.gov (United States)

Laramy, Christine R.; Fong, Lam-Kiu; Jones, Matthew R.; O'Brien, Matthew N.; Schatz, George C.; Mirkin, Chad A.

2017-09-01

Several seed-mediated syntheses of low symmetry anisotropic nanoparticles yield broad product distributions with multiple defect structures. This observation challenges the role of the nanoparticle precursor as a seed for certain syntheses and suggests the possibility of alternate nucleation pathways. Herein, we report a method to probe the role of the nanoparticle precursor in anisotropic nanoparticle nucleation with compositional and structural 'labels' to track their fate. We use the synthesis of gold triangular nanoprisms (Au TPs) as a model system. We propose a mechanism in which, rather than acting as a template, the nanoparticle precursor catalyzes homogenous nucleation of Au TPs.

Bounds on fluid permeability for viscous flow through porous media

International Nuclear Information System (INIS)

Berryman, J.G.

1985-01-01

General properties of variational bounds on Darcy's constant for slow viscous flow through porous media are studied. The bounds are also evaluated numerically for the penetrable sphere model. The bound of Doi depending on two-point correlations and the analytical bound of Weissberg and Prager give comparable results in the low density limit but the analytical bound is superior for higher densities. Prager's bound depending on three-point correlation functions is worse than the analytical bound at low densities but better (although comparable to it) at high densities. A procedure for methodically improving Prager's three point bound is presented. By introducing a Gaussian trial function, the three-point bound is improved by an order of magnitude for moderate values of porosity. The new bounds are comparable in magnitude to the Kozeny--Carman empirical relation for porous materials

Lower bound on inconclusive probability of unambiguous discrimination

International Nuclear Information System (INIS)

Feng Yuan; Zhang Shengyu; Duan Runyao; Ying Mingsheng

2002-01-01

We derive a lower bound on the inconclusive probability of unambiguous discrimination among n linearly independent quantum states by using the constraint of no signaling. It improves the bound presented in the paper of Zhang, Feng, Sun, and Ying [Phys. Rev. A 64, 062103 (2001)], and when the optimal discrimination can be reached, these two bounds coincide with each other. An alternative method of constructing an appropriate measurement to prove the lower bound is also presented

Models and Techniques for Proving Data Structure Lower Bounds

DEFF Research Database (Denmark)

Larsen, Kasper Green

In this dissertation, we present a number of new techniques and tools for proving lower bounds on the operational time of data structures. These techniques provide new lines of attack for proving lower bounds in both the cell probe model, the group model, the pointer machine model and the I...... bound of tutq = (lgd􀀀1 n). For ball range searching, we get a lower bound of tutq = (n1􀀀1=d). The highest previous lower bound proved in the group model does not exceed ((lg n= lg lg n)2) on the maximum of tu and tq. Finally, we present a new technique for proving lower bounds....../O-model. In all cases, we push the frontiers further by proving lower bounds higher than what could possibly be proved using previously known techniques. For the cell probe model, our results have the following consequences: The rst (lg n) query time lower bound for linear space static data structures...

Stacked spheres and lower bound theorem

Indian Academy of Sciences (India)

BASUDEB DATTA

2011-11-20

Nov 20, 2011 ... Preliminaries. Lower bound theorem. On going work. Definitions. An n-simplex is a convex hull of n + 1 affinely independent points. (called vertices) in some Euclidean space R. N . Stacked spheres and lower bound theorem. Basudeb Datta. Indian Institute of Science. 2 / 27 ...

Exponential Lower Bounds For Policy Iteration

OpenAIRE

Fearnley, John

2010-01-01

We study policy iteration for infinite-horizon Markov decision processes. It has recently been shown policy iteration style algorithms have exponential lower bounds in a two player game setting. We extend these lower bounds to Markov decision processes with the total reward and average-reward optimality criteria.

An upper bound on Q-star masses

International Nuclear Information System (INIS)

Hochron, D.R.; Selipsky, S.B.

1992-06-01

Q-stars (the gravitational generalization of Q-balls, strongly bound bulk matter that an appear in field theories of strongly interacting hadrons) are the only known impact objects consistent with the known bulk structure of nuclei and chiral symmetry that evade the Rhoades-Ruffini upper bound of 3.2M circle-dot . Generic bounds are quite weak: M Q-star circle-dot . If, however, we assume that the 1.558 ms pulsar is a Q-star, equilibrium. A stability criteria of rotating fluids place a much stronger upper bound of M c ≤ 5.3M circle-dot on such models under certain special assumptions. This has important implications for heavy compact objects such as Cygnus X-1

Piper betle-mediated green synthesis of biocompatible gold nanoparticles

Science.gov (United States)

Punuri, Jayasekhar Babu; Sharma, Pragya; Sibyala, Saranya; Tamuli, Ranjan; Bora, Utpal

2012-08-01

Here, we report the novel use of the ethonolic leaf extract of Piper betle for gold nanoparticle (AuNP) synthesis. The successful formation of AuNPs was confirmed by UV-visible spectroscopy, and different parameters such as leaf extract concentration (2%), gold salt concentration (0.5 mM), and time (18 s) were optimized. The synthesized AuNPs were characterized with different biophysical techniques such as transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). TEM experiments showed that nanoparticles were of various shapes and sizes ranging from 10 to 35 nm. FT-IR spectroscopy revealed that AuNPs were functionalized with biomolecules that have primary amine group -NH2, carbonyl group, -OH groups, and other stabilizing functional groups. EDX showed the presence of the elements on the surface of the AuNPs. FT-IR and EDX together confirmed the presence of biomolecules bounded on the AuNPs. Cytotoxicity of the AuNPs was tested on HeLa and MCF-7 cancer cell lines, and they were found to be nontoxic, indicating their biocompatibility. Thus, synthesized AuNPs have potential for use in various biomedical applications.

Upper bounds for reversible circuits based on Young subgroups

DEFF Research Database (Denmark)

Abdessaied, Nabila; Soeken, Mathias; Thomsen, Michael Kirkedal

2014-01-01

We present tighter upper bounds on the number of Toffoli gates needed in reversible circuits. Both multiple controlled Toffoli gates and mixed polarity Toffoli gates have been considered for this purpose. The calculation of the bounds is based on a synthesis approach based on Young subgroups...... that results in circuits using a more generalized gate library. Starting from an upper bound for this library we derive new bounds which improve the existing bound by around 77%....

(BDMCA) Nanoparticles

African Journals Online (AJOL)

Erah

Available online at http://www.tjpr.org. Research Article ... Methods: Nanoparticle formulations were fabricated by a double emulsion solvent evaporation technique using .... Characterization of BDMCA nanoparticles. The nanoparticle ...

Uniform Bounds for Black--Scholes Implied Volatility

OpenAIRE

Tehranchi, Michael Rummine

2016-01-01

In this note, Black--Scholes implied volatility is expressed in terms of various optimization problems. From these representations, upper and lower bounds are derived which hold uniformly across moneyness and call price. Various symmetries of the Black--Scholes formula are exploited to derive new bounds from old. These bounds are used to reprove asymptotic formulas for implied volatility at extreme strikes and/or maturities. the Society for Industrial and Applied Mathematics 10.1137/14095248X

Phase I/II dose-finding study of nanoparticle albumin-bound paclitaxel (nab®-Paclitaxel) plus Cisplatin as Treatment for Metastatic Nasopharyngeal Carcinoma.

Science.gov (United States)

Huang, Yan; Liang, Wenhua; Yang, Yunpeng; Zhao, Liping; Zhao, Hongyun; Wu, Xuan; Zhao, Yuanyuan; Zhang, Yang; Zhang, Li

2016-07-13

This phase I/II study aimed to determine the maximum tolerated dose (MTD) of nanoparticle albumin-bound paclitaxel (nab (®)-paclitaxel) plus cisplatin as treatment for metastatic nasopharyngeal carcinoma (NPC). Patients were enrolled into 1 of 3 dose cohorts, each with 21-day treatment cycles: 1) intravenous (IV) nab-paclitaxel 260 mg/m(2) on day 1; 2) IV nab-paclitaxel 140 mg/m(2) on days 1 and 8; 3) IV nab-paclitaxel 100 mg/m(2) on days 1, 8, and 15. All patients received IV cisplatin 75 mg/m(2) on day 1. Treatment continued for 4-6 cycles, or until progression or unacceptable toxicity. If more than one-third of the patients in a cohort experienced a dose-limiting toxicity (DLT), the dose used in the previous cohort would be designated the MTD. Secreted protein acidic and rich in cysteine (SPARC) expression was detected by immunohistochemistry staining. Sixty-nine patients were enrolled, of whom 64 and 67 were eligible for efficacy and safety analysis, respectively. Two DLTs occurred in cohort 1 (grade 4 febrile neutropenia, grade 3 myalgia), none occurred in cohort 2, and 2 occurred in cohort 3 (both grade 3 fatigue). The MTD was not reached. Partial responses were achieved by 42 patients, 15 had stable disease, and 7 had progressive disease, giving an overall response rate of 66 %. Median progression-free survival was 9 months (95 % CI, 6-12 months). Grade ≥ 3 adverse events were mainly hematologic. There was no significant difference between the 3 cohorts with respect to efficacy or safety. Biomarker analyses indicated that stromal, rather than tumoral, SPARC may predict the response to nab-paclitaxel in NPC. Our findings suggest that nab-paclitaxel plus cisplatin is a highly active regimen with moderate toxicity for the treatment of metastatic NPC, which warrants further investigation in a phase III study. ClinicalTrials.gov ID: NCT01735409 . The trial was registered on November 20th, 2012.

Toward tuning the surface functionalization of small ceria nanoparticles

International Nuclear Information System (INIS)

Huang, Xing; Wang, Binghui; Grulke, Eric A.; Beck, Matthew J.

2014-01-01

Understanding and controlling the performance of ceria nanoparticle (CNP) catalysts requires knowledge of the detailed structure and property of CNP surfaces and any attached functional groups. Here we report thermogravimetric analysis results showing that hydrothermally synthesized ∼30 nm CNPs are decorated with 12.9 hydroxyl groups per nm 2 of CNP surface. Quantum mechanical calculations of the density and distribution of bound surface groups imply a scaling relationship for surface group density that balances formal charges in the functionalized CNP system. Computational results for CNPs with only hydroxyl surface groups yield a predicted density of bound hydroxyl groups for ∼30 nm CNPs that is ∼33% higher than measured densities. Quantitative agreement between predicted and measured hydroxyl surface densities is achieved when calculations consider CNPs with both –OH and –O x surface groups. For this more general treatment of CNP surface functionalizations, quantum mechanical calculations predict a range of stable surface group configurations that depend on the chemical potentials of O and H, and demonstrate the potential to tune CNP surface functionalizations by varying temperature and/or partial pressures of O 2 and H 2 O

Effects of Humic and Fulvic Acids on Silver Nanoparticle Stability, Dissolution, and Toxicity

Science.gov (United States)

Gunsolus, Ian L.; Mousavi, Maral P. S.; Hussein, Kadir; Bühlmann, Philippe; Haynes, Christy L.

2015-01-01

The colloidal stability of silver nanoparticles (AgNPs) in natural aquatic environments influences their transport and environmental persistence, while their dissolution to Ag+ influences their toxicity to organisms. Here, we characterize the colloidal stability, dissolution behavior, and toxicity of two industrially relevant classes of AgNPs (i.e., AgNPs stabilized by citrate or polyvinylpyrrolidone) after exposure to natural organic matter (NOM, i.e., Suwannee River Humic and Fulvic Acid Standards and Pony Lake Fulvic Acid Reference). We show that NOM interaction with the nanoparticle surface depends on (i) the NOM’s chemical composition, where sulfur- and nitrogen-rich NOM more significantly increases colloidal stability, and (ii) the affinity of the capping agent for the AgNP surface, where nanoparticles with loosely bound capping agents are more effectively stabilized by NOM. Adsorption of NOM is shown to have little effect on AgNP dissolution under most experimental conditions, the exception being when the NOM is rich in sulfur and nitrogen. Similarly, the toxicity of AgNPs to a bacterial model (Shewanella oneidensis MR-1) decreases most significantly in the presence of sulfur- and nitrogen-rich NOM. Our data suggest that the rate of AgNP aggregation and dissolution in aquatic environments containing NOM will depend on the chemical composition of the NOM, and that the toxicity of AgNPs to aquatic microorganisms is controlled primarily by the extent of nanoparticle dissolution. PMID:26047330

Proximity effect tunneling into virtual bound state alloys

International Nuclear Information System (INIS)

Tang, I.M.; Roongkkeadsakoon, S.

1984-01-01

The effects of a narrow virtual bound state formed by transition metal impurities dissolved in the normal layer of a superconducting proximity effect sandwich are studied. Using standard renormalization techniques, we obtain the changes in the transition temperatures and the jumps in the specific heat at T/sub c/ as a function of the thickness of the normal layer, of the widths of the virtual bound states, and of the impurity concentrations. It is seen that narrow virtual bound states lead to decrease in the transition temperatures, while broad virtual bound states do not. It if further seen that the narrow virtual bound state causes the reduced specific heat jump at T/sub c/ to deviate from the BCS behavior expected of the pure sandwich

A strongly quasiconvex PAC-Bayesian bound

DEFF Research Database (Denmark)

Thiemann, Niklas; Igel, Christian; Wintenberger, Olivier

2017-01-01

We propose a new PAC-Bayesian bound and a way of constructing a hypothesis space, so that the bound is convex in the posterior distribution and also convex in a trade-off parameter between empirical performance of the posterior distribution and its complexity. The complexity is measured by the Ku...

Sharp bounds for periodic solutions of Lipschitzian differential equations

International Nuclear Information System (INIS)

Zevin, A A

2009-01-01

A general system of Lipschitzian differential equations, containing simultaneously terms without delay and with arbitrary constant and time-varying delays, is considered. For the autonomous case, a lower bound for the period of nonconstant periodic solutions, expressed in the respective supremum Lipschitz constants, is found. For nonautonomous periodic equations, explicit upper bounds for the amplitudes and maximum derivatives of periodic solutions are obtained. For all n ≥ 2, the bounds do not depend on n and, in general, are different from that for n = 1. All the bounds are sharp; they are attained in linear differential equations with piece-wise constant deviating arguments. A relation between the obtained bounds and the sharp bounds in other metrics is established

Bounds for nonlinear composites via iterated homogenization

Science.gov (United States)

Ponte Castañeda, P.

2012-09-01

Improved estimates of the Hashin-Shtrikman-Willis type are generated for the class of nonlinear composites consisting of two well-ordered, isotropic phases distributed randomly with prescribed two-point correlations, as determined by the H-measure of the microstructure. For this purpose, a novel strategy for generating bounds has been developed utilizing iterated homogenization. The general idea is to make use of bounds that may be available for composite materials in the limit when the concentration of one of the phases (say phase 1) is small. It then follows from the theory of iterated homogenization that it is possible, under certain conditions, to obtain bounds for more general values of the concentration, by gradually adding small amounts of phase 1 in incremental fashion, and sequentially using the available dilute-concentration estimate, up to the final (finite) value of the concentration (of phase 1). Such an approach can also be useful when available bounds are expected to be tighter for certain ranges of the phase volume fractions. This is the case, for example, for the "linear comparison" bounds for porous viscoplastic materials, which are known to be comparatively tighter for large values of the porosity. In this case, the new bounds obtained by the above-mentioned "iterated" procedure can be shown to be much improved relative to the earlier "linear comparison" bounds, especially at low values of the porosity and high triaxialities. Consistent with the way in which they have been derived, the new estimates are, strictly, bounds only for the class of multi-scale, nonlinear composites consisting of two well-ordered, isotropic phases that are distributed with prescribed H-measure at each stage in the incremental process. However, given the facts that the H-measure of the sequential microstructures is conserved (so that the final microstructures can be shown to have the same H-measure), and that H-measures are insensitive to length scales, it is conjectured

Development and evaluation of polymer nanoparticles for oral delivery of estradiol to rat brain in a model of Alzheimer's pathology.

Science.gov (United States)

Mittal, G; Carswell, H; Brett, R; Currie, S; Kumar, M N V Ravi

2011-03-10

The purpose of this study was to develop tween 80 (T-80) coated polylactide-co-glycolide (PLGA) nanoparticles that can deliver estradiol to the brain upon oral administration. Estradiol containing nanoparticles were made by a single emulsion technique and T-80 coating was achieved by incubating the re-constituted nanoparticles at different concentrations of T-80. The process of T-80 coating on the nanoparticles was optimized and the pharmacokinetics of estradiol nanoparticles was studied as a function of T-80 coating. The nanoparticles were then evaluated in an ovariectomized (OVX) rat model of Alzheimer's disease (AD) that mimics the postmenopausal conditions. The nanoparticles bound T-80 were found to proportionally increase from 9.72 ± 1.07 mg to 63.84 ± 3.59 mg with an increase in the initial concentration T-80 from 1% to 5% and were stable in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). Orally administered T-80 coated nanoparticles resulted in significantly higher brain estradiol levels after 24h (1.969 ± 0.197 ng/g tissue) as compared to uncoated ones (1.105 ± 0.136 ng/g tissue) at a dose of 0.2mg/rat, suggesting a significant role of surface coating. Moreover, these brain estradiol levels were almost similar to those obtained after administration of the same dose of drug suspension via 100% bioavailable intramuscular route (2.123 ± 0.370 ng/g tissue), indicating the increased fraction of bioavailable drug reaching the brain when administered orally. Also, the nanoparticle treated group was successful in preventing the expression of amyloid beta-42 (Aβ42) immunoreactivity in the hippocampus region of brain. Together, the results indicate the potential of nanoparticles for oral delivery of estradiol to brain. Copyright © 2010 Elsevier B.V. All rights reserved.

Four-quark bound states

International Nuclear Information System (INIS)

Zouzou, S.

1986-01-01

In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include the virtual meson-meson components of the wave function. With standard two-body potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic (anti Qanti Qqq) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q'qq) baryons. (orig.)

Merely Measuring the UV-Visible Spectrum of Gold Nanoparticles Can Change Their Charge State.

Science.gov (United States)

Navarrete, Jose; Siefe, Chris; Alcantar, Samuel; Belt, Michael; Stucky, Galen D; Moskovits, Martin

2018-02-14

Metallic nanostructures exhibit a strong plasmon resonance at a wavelength whose value is sensitive to the charge density in the nanostructure, its size, shape, interparticle coupling, and the dielectric properties of its surrounding medium. Here we use UV-visible transmission and reflectance spectroscopy to track the shifts of the plasmon resonance in an array of gold nanoparticles buried under metal-oxide layers of varying thickness produced using atomic layer deposition (ALD) and then coated with bulk layers of one of three metals: aluminum, silver, or gold. A significant shift in the plasmon resonance was observed and a precise value of ω p , the plasmon frequency of the gold comprising the nanoparticles, was determined by modeling the composite of gold nanoparticles and metal-oxide layer as an optically homogeneous film of core-shell particles bounded by two substrates: one of quartz and the other being one of the aforementioned metals, then using a Maxwell-Garnett effective medium expression to extract ω p for the gold nanoparticles before and after coating with the bulk metals. Under illumination, the change in the charge density of the gold nanoparticles per particle determined from the change in the values of ω p is found to be some 50-fold greater than what traditional electrostatic contact electrification models compute based on the work function difference of the two conductive materials. Moreover, when using bulk gold as the capping layer, which should have resulted in a negligible charge exchange between the gold nanoparticles and the bulk gold, a significant charge transfer from the bulk gold layer to the nanoparticles was observed as with the other metals. We explain these observations in terms of the "plasmoelectric effect", recently described by Atwater and co-workers, in which the gold nanoparticles modify their charge density to allow their resonant wavelength to match that of the incident light, thereby achieving, a lower value of the

Thermalization Time Bounds for Pauli Stabilizer Hamiltonians

Science.gov (United States)

Temme, Kristan

2017-03-01

We prove a general lower bound to the spectral gap of the Davies generator for Hamiltonians that can be written as the sum of commuting Pauli operators. These Hamiltonians, defined on the Hilbert space of N-qubits, serve as one of the most frequently considered candidates for a self-correcting quantum memory. A spectral gap bound on the Davies generator establishes an upper limit on the life time of such a quantum memory and can be used to estimate the time until the system relaxes to thermal equilibrium when brought into contact with a thermal heat bath. The bound can be shown to behave as {λ ≥ O(N^{-1} exp(-2β overline{ɛ}))}, where {overline{ɛ}} is a generalization of the well known energy barrier for logical operators. Particularly in the low temperature regime we expect this bound to provide the correct asymptotic scaling of the gap with the system size up to a factor of N -1. Furthermore, we discuss conditions and provide scenarios where this factor can be removed and a constant lower bound can be proven.

Information-Theoretic Bounded Rationality and ε-Optimality

Directory of Open Access Journals (Sweden)

Daniel A. Braun

2014-08-01

Full Text Available Bounded rationality concerns the study of decision makers with limited information processing resources. Previously, the free energy difference functional has been suggested to model bounded rational decision making, as it provides a natural trade-off between an energy or utility function that is to be optimized and information processing costs that are measured by entropic search costs. The main question of this article is how the information-theoretic free energy model relates to simple ε-optimality models of bounded rational decision making, where the decision maker is satisfied with any action in an ε-neighborhood of the optimal utility. We find that the stochastic policies that optimize the free energy trade-off comply with the notion of ε-optimality. Moreover, this optimality criterion even holds when the environment is adversarial. We conclude that the study of bounded rationality based on ε-optimality criteria that abstract away from the particulars of the information processing constraints is compatible with the information-theoretic free energy model of bounded rationality.

Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

OpenAIRE

Yang Yongkun; Burkhard Peter

2012-01-01

Abstract Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs...

Binding kinetics of magnetic nanoparticles on latex beads and yeast cells studied by magnetorelaxometry

International Nuclear Information System (INIS)

Eberbeck, Dietmar; Bergemann, Christian; Hartwig, Stefan; Steinhoff, Uwe; Trahms, Lutz

2005-01-01

The ion exchange mediated binding of magnetic nanoparticles (MNP) to modified latex spheres and yeast cells was quantified using magnetorelaxometry. By fitting subsequently recorded relaxation curves, the kinetics of the binding reactions was extracted. The signal of MNP with weak ion exchanger groups bound to latex and yeast cells scales linearly with the concentration of latex beads or yeast cells whereas that of MNP with strong ion exchanger groups is proportional to the square root of concentration. The binding of the latter leads to a much stronger aggregation of yeast cells than the former MNP

Application of functionalized lanthanide-based nanoparticles for the detection of okadaic acid-specific immunoglobulin G.

Science.gov (United States)

Stipić, Filip; Pletikapić, Galja; Jakšić, Željko; Frkanec, Leo; Zgrablić, Goran; Burić, Petra; Lyons, Daniel M

2015-01-29

Marine biotoxins are widespread in the environment and impact human health via contaminated shellfish, causing diarrhetic, amnesic, paralytic, or neurotoxic poisoning. In spite of this, methods for determining if poisoning has occurred are limited. We show the development of a simple and sensitive luminescence resonance energy transfer (LRET)-based concept which allows the detection of anti-okadaic acid rabbit polyclonal IgG (mouse monoclonal IgG1) using functionalized lanthanide-based nanoparticles. Upon UV excitation, the functionalized nanoparticles were shown to undergo LRET with fluorophore-labeled anti-okadaic acid antibodies which had been captured and bound by okadaic acid-decorated nanoparticles. The linear dependence of fluorescence emission intensity with antigen-antibody binding events was recorded in the nanomolar to micromolar range, while essentially no LRET signal was detected in the absence of antibody. These results may find applications in new, cheap, and robust sensors for detecting not only immune responses to biotoxins but also a wide range of biomolecules based on antigen-antibody recognition systems. Further, as the system is based on solution chemistry it may be sufficiently simple and versatile to be applied at point-of-care.

Bounded-Angle Iterative Decoding of LDPC Codes

Science.gov (United States)

Dolinar, Samuel; Andrews, Kenneth; Pollara, Fabrizio; Divsalar, Dariush

2009-01-01

Bounded-angle iterative decoding is a modified version of conventional iterative decoding, conceived as a means of reducing undetected-error rates for short low-density parity-check (LDPC) codes. For a given code, bounded-angle iterative decoding can be implemented by means of a simple modification of the decoder algorithm, without redesigning the code. Bounded-angle iterative decoding is based on a representation of received words and code words as vectors in an n-dimensional Euclidean space (where n is an integer).

Unexpected strong attraction in the presence of continuum bound state

International Nuclear Information System (INIS)

Delfino, A.; Frederico, T.

1992-06-01

The result of few-particle ground-state calculation employing a two-particle non-local potential supporting a continuum bound state in addition to a negative-energy bound state has occasionally revealed unexpected large attraction in producing a very strongly bound ground state. In the presence of the continuum bound state the difference of phase shift between zero and infinite energies has an extra jump of φ as in the presence of an additional bound state. The wave function of the continuum bound state is identical with that of a strongly bound negative-energy state, which leads us to postulate a pseudo bound state in the two-particle system in order to explain the unexpected attraction. The role of the Pauli forbidden states is expected to be similar to these pseudo states. (author)

On the Feng-Rao bound for generalized hamming weights

DEFF Research Database (Denmark)

Geil, Hans Olav; Thommesen, Christian

2006-01-01

The Feng-Rao bound gives good estimates of the minimum distance of a large class of codes. In this work we are concerned with the problem of how to extend the Feng-Rao bound so that it deals with all the generalized Hamming weights. The problem was solved by Heijnen and Pellikaan in [7] for a large...... family of codes that includes the duals of one-point geometric Goppa codes and the q-ary Reed-Muller codes, but not the Feng-Rao improved such ones. We show that Heijnen and Pellikaan's results holds for the more general class of codes for which the traditional Feng-Rao bound can be applied. We also...... establish the connection to the Shibuya-Sakaniwa bound for generalized Hamming weights ([15], [16], [17], [18], [19] and [20]). More precisely we show that the Shibuya-Sakaniwa bound is a consequence of the extended Feng-Rao bound. In particular the extended Feng-Rao bound gives always at least as good...

On the Feng-Rao bound for generalized Hamming weights

DEFF Research Database (Denmark)

Geil, Olav; Thommesen, Christian

2005-01-01

The Feng-Rao bound gives good estimates of the minimum distance of a large class of codes. In this work we are concerned with the problem of how to extend the Feng-Rao bound so that it deals with all the generalized Hamming weights. The problem was solved by Heijnen and Pellikaan in [7] for a large...... family of codes that includes the duals of one-point geometric Goppa codes and the q-ary Reed-Muller codes, but not the Feng-Rao improved such ones. We show that Heijnen and Pellikaan’s results holds for the more general class of codes for which the traditional Feng-Rao bound can be applied. We also...... establish the connection to the Shibuya-Sakaniwa bound for generalized Hamming weights ([15], [16], [17], [18], [19] and [20]). More precisely we show that the Shibuya-Sakaniwa bound is a consequence of the extended Feng-Rao bound. In particular the extended Feng-Rao bound gives always at least as good...

Characterization of nanoparticles released during construction of photocatalytic pavements using engineered nanoparticles

International Nuclear Information System (INIS)

Dylla, Heather; Hassan, Marwa M.

2012-01-01

With the increasing use of titanium dioxide (TiO 2 ) nanoparticles in self-cleaning materials such as photocatalytic concrete pavements, the release of nanoparticles into the environment is inevitable. Nanoparticle concentration, particle size, surface area, elemental composition, and surface morphology are pertinent to determine the associated risks. In this study, the potential of exposure to synthetic nanoparticles released during construction activities for application of photocatalytic pavements was measured during laboratory-simulated construction activities of photocatalytic mortar overlays and in an actual field application of photocatalytic spray coat. A scanning mobility particle sizer system measured the size distribution of nanoparticles released during laboratory and field activities. Since incidental nanoparticles are released during construction activities, nanoparticle emissions were compared to those from similar activities without nano-TiO 2 . Nanoparticle counts and size distribution suggest that synthetic nanoparticles are released during application of photocatalytic pavements. In order to identify the nanoparticle source, nanoparticles were also collected for offline characterization using transmission electron microscopy. However, positive identification of synthetic nanoparticles was not possible due to difficulties in obtaining high-resolution images. As a result, further research is recommended to identify nanoparticle composition and sources.

Remarks on Bousso's covariant entropy bound

CERN Document Server

Mayo, A E

2002-01-01

Bousso's covariant entropy bound is put to the test in the context of a non-singular cosmological solution of general relativity found by Bekenstein. Although the model complies with every assumption made in Bousso's original conjecture, the entropy bound is violated due to the occurrence of negative energy density associated with the interaction of some the matter components in the model. We demonstrate how this property allows for the test model to 'elude' a proof of Bousso's conjecture which was given recently by Flanagan, Marolf and Wald. This corroborates the view that the covariant entropy bound should be applied only to stable systems for which every matter component carries positive energy density.

Generalized Hofmann quantum process fidelity bounds for quantum filters

Science.gov (United States)

Sedlák, Michal; Fiurášek, Jaromír

2016-04-01

We propose and investigate bounds on the quantum process fidelity of quantum filters, i.e., probabilistic quantum operations represented by a single Kraus operator K . These bounds generalize the Hofmann bounds on the quantum process fidelity of unitary operations [H. F. Hofmann, Phys. Rev. Lett. 94, 160504 (2005), 10.1103/PhysRevLett.94.160504] and are based on probing the quantum filter with pure states forming two mutually unbiased bases. Determination of these bounds therefore requires far fewer measurements than full quantum process tomography. We find that it is particularly suitable to construct one of the probe bases from the right eigenstates of K , because in this case the bounds are tight in the sense that if the actual filter coincides with the ideal one, then both the lower and the upper bounds are equal to 1. We theoretically investigate the application of these bounds to a two-qubit optical quantum filter formed by the interference of two photons on a partially polarizing beam splitter. For an experimentally convenient choice of factorized input states and measurements we study the tightness of the bounds. We show that more stringent bounds can be obtained by more sophisticated processing of the data using convex optimization and we compare our methods for different choices of the input probe states.

Twisting, supercoiling and stretching in protein bound DNA

Science.gov (United States)

Lam, Pui-Man; Zhen, Yi

2018-04-01

We have calculated theoretical results for the torque and slope of the twisted DNA, with various proteins bound on it, using the Neukirch-Marko model, in the regime where plectonemes exist. We found that the torque in the protein bound DNA decreases compared to that in the bare DNA. This is caused by the decrease in the free energy g(f) , and hence the smaller persistence lengths, in the case of protein bound DNA. We hope our results will encourage experimental investigations of supercoiling in protein bound DNA, which can provide further tests of the Neukirch-Marko model.

The bound state problem and quark confinement

International Nuclear Information System (INIS)

Chaichian, M.; Demichev, A.P.; Nelipa, N.F.

1980-01-01

A quantum field-theoretic model in which quark is confined is considered. System of equations for the Green functions of colour singlet and octet bound states is obtained. The method is based on the nonperturbative Schwinger-Dyson equations with the use of Slavnov-Taylor identities. It is shown that in the framework of the model if there exist singlet, then also exist octet bound states of the quark-antiquark system. Thus in general, confinement of free quarks does not mean absence of their coloured bound states. (author)

``Carbon Credits'' for Resource-Bounded Computations Using Amortised Analysis

Science.gov (United States)

Jost, Steffen; Loidl, Hans-Wolfgang; Hammond, Kevin; Scaife, Norman; Hofmann, Martin

Bounding resource usage is important for a number of areas, notably real-time embedded systems and safety-critical systems. In this paper, we present a fully automatic static type-based analysis for inferring upper bounds on resource usage for programs involving general algebraic datatypes and full recursion. Our method can easily be used to bound any countable resource, without needing to revisit proofs. We apply the analysis to the important metrics of worst-case execution time, stack- and heap-space usage. Our results from several realistic embedded control applications demonstrate good matches between our inferred bounds and measured worst-case costs for heap and stack usage. For time usage we infer good bounds for one application. Where we obtain less tight bounds, this is due to the use of software floating-point libraries.

Multivalent system for therapy of non-Hod king lymphomas based on Anti-CD20 conjugated to gold nanoparticles

International Nuclear Information System (INIS)

Miranda O, R. M.

2014-01-01

In recent publications has been reported that gold nanoparticles have an effect in reducing the expression of the oncogene Bcl -2 and have a high biocompatibility , this is the importance for using gold nanoparticles for this work. The antibody CD20 is an antibody that specifically binds to that over expressed CD20 antigen on the cell membrane of B lymphoma cell non- Hodgkin (cell line Raji) behold the importance of combining this bio molecule to gold nanoparticles since they have a high specificity with CD20 positive cells , also to carry out the antigen- antibody immunological reactions triggered mediating cell lysis, possibly by cytotoxicity and apoptosis. Therefore, this system must have characteristics of both components to eliminate B cell non- Hodgkin lymphoma.In this work it was studied a multivalent system composed of gold nanoparticles and anti-CD20 antibody, the term multi valency refers to the number of biomolecules attached to the surface of the gold nanoparticle. The synthesis and characterization of the gold nanoparticles and the multivalent system was performed and the effect of the multivalent system on the expression of oncogene Bcl-2 (group of proteins associated with the apoptotic pathway) was evaluated. Characterization of raw materials and the multivalent system was performed using spectroscopic and microscopic techniques, this to verify structural changes in raw materials and thus confirm the formation of CD20 binding to the surface of the nanoparticle gold by the bond between gold and sulfur in the cysteines of CD20. Taking advantage that the metal nanoparticles have the optical property of surface plasmon resonance, the absorption of gold nanoparticles was measured on the UV-Vis as it is affected by the surface molecules bind to it, showing a bathochromic displacement effected. The hydrodynamic diameter of the gold nanoparticles was measured to verify that the antibody is bound to the surface; this evidence was complemented by micrographs

Improved rigorous upper bounds for transport due to passive advection described by simple models of bounded systems

International Nuclear Information System (INIS)

Kim, Chang-Bae; Krommes, J.A.

1988-08-01

The work of Krommes and Smith on rigorous upper bounds for the turbulent transport of a passively advected scalar [/ital Ann. Phys./ 177:246 (1987)] is extended in two directions: (1) For their ''reference model,'' improved upper bounds are obtained by utilizing more sophisticated two-time constraints which include the effects of cross-correlations up to fourth order. Numerical solutions of the model stochastic differential equation are also obtained; they show that the new bounds compare quite favorably with the exact results, even at large Reynolds and Kubo numbers. (2) The theory is extended to take account of a finite spatial autocorrelation length L/sub c/. As a reasonably generic example, the problem of particle transport due to statistically specified stochastic magnetic fields in a collisionless turbulent plasma is revisited. A bound is obtained which reduces for small L/sub c/ to the quasilinear limit and for large L/sub c/ to the strong turbulence limit, and which provides a reasonable and rigorous interpolation for intermediate values of L/sub c/. 18 refs., 6 figs

Synthesis and characterization of folate decorated albumin bio-conjugate nanoparticles loaded with a synthetic curcumin difluorinated analogue.

Science.gov (United States)

Gawde, Kaustubh A; Kesharwani, Prashant; Sau, Samaresh; Sarkar, Fazlul H; Padhye, Subhash; Kashaw, Sushil K; Iyer, Arun K

2017-06-15

Albumin-bound paclitaxel colloidal nanoparticle (Abraxane®) is an FDA approved anticancer formulation available in the market. It is a suspension which is currently used therapeutically for treating cancers of the breast, lung, and pancreas among others. CDF is a novel new and potent synthetic curcumin analogue that is widely used for breast and ovarian cancer. The aim of this study was to use biocompatible albumin as well as folate decorated albumin to formulate colloidal nanoparticles encapsulating curcumin difluorinated (CDF). CDF has demonstrated a 16-fold improvement in stability and remarkable anticancer potency compared to its natural derivative, curcumin. CDF showed marked inhibition of cancer cell growth through down-regulation of multiple miRNAs, up-regulation of phosphatase and tensin homolog (PTEN), and attenuation of histone methyl transferase EZH2. However, CDF is highly hydrophobic and photodegradable with sparing aqueous solubility. In this study, we have formulated albumin nanoparticle using a modified desolvation method, which yielded high CDF loading in a nanoformulation. The physicochemical properties of CDF loaded albumin and folate-decorated albumin nanosuspensions were assessed for particle size, morphology, zeta potential, drug encapsulation efficiency/loading, solubility and drug release. Importantly, the folate ligand decorated albumin nanoparticles were formulated in principle to passively and actively target folate-overexpressing-cancers. In this study, the synthesis and optimization of BSA and folate decorated BSA conjugated CDF nanoparticles are assessed in detail that will be useful for its future clinical translation. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of soil-bound residues of malathion on microbial activities

International Nuclear Information System (INIS)

Hussain, A.; Iqbal, Z.; Asi, M.R.; Tahira, R.; Chudhary, J.A.

2001-01-01

The effect of soil-bound residues of malathion on CO/sub 2/ evolution, dehydrogenase activity and some nitrogen transformations in a loam soil was investigated under laboratory conditions. The soil samples containing bound residues arising from 10 mg g-1 of the applied malathion were mixed in equal quantity with fresh soil and compared with solvent extracted control soil without bound residues (extracted in the same way as soil containing bound residues). Another control comprising un extracted fresh soil without bound residues was also kept to study the effect of solvent extraction on the biological activity. Rate of Carbon mineralization (CO/sub 2/ evolution) was decreased in the presence of soil-bound residues of malathion. Bound residues also affected dehydrogenase activity of soil. Over 40% inhibition of dehydrogenase activity was observed after 4 days and the inhibition persisted at least for 12 days. Nitrogen mineralization was stimulated in soil containing bound residues of malathion and this stimulatory effect increased with time of incubation. Nitrification was partially inhibited in the presence of soil-bound residues of malathion. The inhibitory effect of the soil-bound residues on nitrification did not show much variation with time. The soil-bound residues did not affect denitrification rate (N/sub 2/O evolution). Nitrogen fixation (acetylene reduction) was partially inhibited in soil amended with bound residues of malathion and the inhibitory effect persisted for at least one week. In general, soil bound residues of malathion inhibited CO/sub 2/ evolution, dehydrogenase activity, nitrification and nitrogen fixation while mineralization of nitrogen was stimulated. Denitrification was not affected by the applied insecticide. (author)

Generalized surface tension bounds in vacuum decay

Science.gov (United States)

Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.

2018-02-01

Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.

Bound entanglement and local realism

International Nuclear Information System (INIS)

Kaszlikowski, Dagomir; Zukowski, Marek; Gnacinski, Piotr

2002-01-01

We show using a numerical approach, which gives necessary and sufficient conditions for the existence of local realism, that the bound entangled state presented in Bennett et al. [Phys. Rev. Lett. 82, 5385 (1999)] admits a local and realistic description. We also find the lowest possible amount of some appropriate entangled state that must be ad-mixed to the bound entangled state so that the resulting density operator has no local and realistic description and as such can be useful in quantum communication and quantum computation

Green synthesis of Fe nanoparticles using eucalyptus leaf extracts for treatment of eutrophic wastewater

International Nuclear Information System (INIS)

Wang, Ting; Jin, Xiaoying; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2014-01-01

Iron nanoparticles were firstly synthesized through a one-step room-temperature biosynthetic route using eucalyptus leaf extracts (EL-Fe NPs). Scanning electron microscopy (SEM) and X-ray energy-dispersive spectrometer (EDS) confirmed the successful synthesis of the spheroidal iron nanoparticles. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared spectrometer (FTIR) indicated that some polyphenols are bound to the surfaces of EL-Fe NPs as a capping/stabilizing agent. Reactivity of EL-Fe NPs was evaluated for the treatment of swine wastewater and results indicated that 71.7% of total N and 84.5% of COD were removed, respectively. This demonstrated the tremendous potential of EL-Fe NPs for in situ remediation of eutrophic wastewater. - Highlights: •Fe NPs were firstly synthesized through a one-step using eucalyptus leaf extracts. •Fe NPs was evaluated by remediating swine wastewater. •71.7% of total N and 84.5% of COD was removed. •Fe NPs for in situ remediation of eutrophic wastewater

Green synthesis of Fe nanoparticles using eucalyptus leaf extracts for treatment of eutrophic wastewater

Energy Technology Data Exchange (ETDEWEB)

Wang, Ting; Jin, Xiaoying [School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian (China); Chen, Zuliang, E-mail: Zuliang.chen@unisa.edu.au [School of Environmental Science and Engineering, Fujian Normal University, Fuzhou 350007, Fujian (China); Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of Environments, Mawson Lakes, SA 5095 (Australia); Megharaj, Mallavarapu; Naidu, Ravendra [Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095 (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of Environments, Mawson Lakes, SA 5095 (Australia)

2014-01-01

Iron nanoparticles were firstly synthesized through a one-step room-temperature biosynthetic route using eucalyptus leaf extracts (EL-Fe NPs). Scanning electron microscopy (SEM) and X-ray energy-dispersive spectrometer (EDS) confirmed the successful synthesis of the spheroidal iron nanoparticles. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared spectrometer (FTIR) indicated that some polyphenols are bound to the surfaces of EL-Fe NPs as a capping/stabilizing agent. Reactivity of EL-Fe NPs was evaluated for the treatment of swine wastewater and results indicated that 71.7% of total N and 84.5% of COD were removed, respectively. This demonstrated the tremendous potential of EL-Fe NPs for in situ remediation of eutrophic wastewater. - Highlights: •Fe NPs were firstly synthesized through a one-step using eucalyptus leaf extracts. •Fe NPs was evaluated by remediating swine wastewater. •71.7% of total N and 84.5% of COD was removed. •Fe NPs for in situ remediation of eutrophic wastewater.

Fabrication and Application of Iron(III-Oxide Nanoparticle/Polydimethylsiloxane Composite Cone in Microfluidic Channels

Directory of Open Access Journals (Sweden)

Cheng-Chun Huang

2012-01-01

Full Text Available This paper presented the fabrication and applications of an iron(III-oxide nanoparticle/polydimethylsiloxane (PDMS cone as a component integrated in lab on a chip. The two main functions of this component were to capture magnetic microbeads in the microfluid and to mix two laminar fluids by generating disturbance. The iron(III-oxide nanoparticle/PDMS cone was fabricated by automatic dispensing and magnetic shaping. Three consecutive cones of 300 μm in height were asymmetrically placed along a microchannel of 2 mm in width and 1.1 mm in height. Flow passing the cones was effectively redistributed for Renolds number lower than . Streptavidin-coated magnetic microbeads which were bound with biotin were successfully captured by the composite cones as inspected under fluorescence microscope. The process parameters for fabricating the composite cones were investigated. The fabricated cone in the microchannel could be applied in lab on a chip for bioassay in the future.

Linker-mediated assembly of gold nanoparticles into multimeric motifs

Energy Technology Data Exchange (ETDEWEB)

Sikora, Mateusz; Cieplak, Marek [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland); Szymczak, Piotr [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ulica Hoza 69, 00-681 Warsaw (Poland); Thompson, Damien, E-mail: mc@ifpan.edu.pl [Tyndall National Institute, Lee Maltings, University College Cork, Cork (Ireland)

2011-11-04

We present a theoretical description of linker-mediated self-assembly of gold nanoparticles (Au-NP). Using mesoscale simulations with a coarse-grained model for the Au NPs and dirhenium-based linker molecules, we investigate the conditions under which large clusters can grow and construct a phase diagram that identifies favorable growth conditions in terms of floating and bound linker concentrations. The findings can be considered as generic, as we expect other NP-linker systems to behave in a qualitatively similar way. In particular, we also discuss the case of antibody-functionalised Au NPs connected by the C-reactive proteins (CRPs). We extract some general rules for NP linking that may aid the production of size- and shape-specific NP clusters for technology applications.

Inequalities and bounds for nucleon-nucleon scattering

International Nuclear Information System (INIS)

Ramandurai, K.S.

1979-08-01

The objective of this work is to derive model-independent inequalities and bounds for nucleon-nucleon elastic scattering amplitudes based on well-established theoretical principles and symmetries. Two classes of methods are used: algebraic and variational. In the algebraic part, the author derives inequalities and bounds for NN amplitudes and observables using their mutual relations and x symmetries. In the variational part, he employs Lagrange's method of undetermined multipliers to evaluate the bounds. He tests the predictions of a sample of proposed phase shifts at three different energies using the results obtained

Conductivity bound from dirty black holes

Energy Technology Data Exchange (ETDEWEB)

Bitaghsir Fadafan, Kazem, E-mail: bitaghsir@shahroodut.ac.ir

2016-11-10

We propose a lower bound of the dc electrical conductivity in strongly disordered, strongly interacting quantum field theories using holography. We study linear response of black holes with broken translational symmetry in Einstein–Maxwell-dilaton theories of gravity. Using the generalized Stokes equations at the horizon, we derive the lower bound of the electrical conductivity for the dual two dimensional disordered field theory.

Braneworld black holes and entropy bounds

Directory of Open Access Journals (Sweden)

Y. Heydarzade

2018-01-01

Full Text Available The Bousso's D-bound entropy for the various possible black hole solutions on a 4-dimensional brane is checked. It is found that the D-bound entropy here is apparently different from that of obtained for the 4-dimensional black hole solutions. This difference is interpreted as the extra loss of information, associated to the extra dimension, when an extra-dimensional black hole is moved outward the observer's cosmological horizon. Also, it is discussed that N-bound entropy is hold for the possible solutions here. Finally, by adopting the recent Bohr-like approach to black hole quantum physics for the excited black holes, the obtained results are written also in terms of the black hole excited states.

[In vitro early detection of amyloid plaques in Alzheimer's disease by Pittsburgh compound B-modified magnetic nanoparticles].

Science.gov (United States)

Zeng, J Q; Wu, J Q; Li, M H; Wang, P J

2017-11-07

Objective: To construct magnetic nanoparticles targeting β-amyloid (Aβ) plaques, the pathological biomarker of Alzheimer's disease (AD) and to study their binding capability in vitro . Methods: Superparamagnetic nanoparticles Mn(0.6)Zn(0.4)Fe(2)O(4) (MZF) were coated with amphiphilic star-block copolymeric micelles and modified with Aβ-specific probe Pittsburgh compound B (PiB) to construct a novel magnetic nanoparticle MZF-PiB, which specifically targeted amyloid plaques. Transmission electron microscope was used to study the morphological features of MZF-PiB. Superparamagnetism of MZF-PiB was assessed by its r(2) relaxation rate by using 3.0 T MRI scanner. Cytotoxic test was applied to determine biosafety of MZF-PiB nanoparticles in differentiated human neuroblastoma cells (SH-SY5Y) and Madin-Darby canine kidney (MDCK). In vitro binding tests were conducted via immunohistochemistry on 6-month old AD mice brain sections. Differences of cell viability between groups were compared with one-way analysis of variance. Results: MZF-PiB nanoparticles were successfully constructed. Transmission electron microscope images showed that the nanoparticles were about 100 nm in size. The r(2) relaxation rate was 163.11 mMS(-1). No differences were found in cell viability of SH-SY5Y and MDCK incubated with MZF-PiB suspension for 24 h or 48 h when compared with those of untreated cells ( F =2.336, 2.539, 0.293, 1.493, all P >0.05). In vitro binding tests indicated that the MZF-PiB were specifically bound to amyloid plaques. The smallest size of detected plaques was 27 μm. Conclusion: PiB-modified nanoparticles targeting Aβ are biologically safe and highly superparamagnetic, possessing the capability to detect amyloid plaques early in vitro and the potential for early diagnosis of AD.

Classical Physics and the Bounds of Quantum Correlations.

Science.gov (United States)

Frustaglia, Diego; Baltanás, José P; Velázquez-Ahumada, María C; Fernández-Prieto, Armando; Lujambio, Aintzane; Losada, Vicente; Freire, Manuel J; Cabello, Adán

2016-06-24

A unifying principle explaining the numerical bounds of quantum correlations remains elusive, despite the efforts devoted to identifying it. Here, we show that these bounds are indeed not exclusive to quantum theory: for any abstract correlation scenario with compatible measurements, models based on classical waves produce probability distributions indistinguishable from those of quantum theory and, therefore, share the same bounds. We demonstrate this finding by implementing classical microwaves that propagate along meter-size transmission-line circuits and reproduce the probabilities of three emblematic quantum experiments. Our results show that the "quantum" bounds would also occur in a classical universe without quanta. The implications of this observation are discussed.

Photophysics of aggregated 9-methylthiacarbocyanine bound to polyanions

Science.gov (United States)

Chibisov, Alexander K.; Görner, Helmut

2002-05-01

The photophysical properties of 3,3 '-diethyl-9-methylthiacarbocyanine (DTC) were studied in the presence of polystyrene sulfonate (PSS), polyacrylic acid (PAA) and polymethacrylic acid (PMA). The absorption spectra reflect a monomer/dimer equilibrium in neat aqueous solution and a shift towards bound H-aggregates, bound dimers and bound monomers on increasing the ratio of polyanion residue to dye concentrations ( r). These equilibria also determine the photodeactivation modes of DTC. The fluorescence intensity is reduced, when dimers and aggregates are present and strongly enhanced for low dye loading ( r=10 4). In contrast, the quantum yield of intersystem crossing is enhanced for bound dimers ( r=10 3).

The algebras of bounded and essentially bounded Lebesgue measurable functions

Directory of Open Access Journals (Sweden)

Mortini Raymond

2017-04-01

Full Text Available Let X be a set in ℝn with positive Lebesgue measure. It is well known that the spectrum of the algebra L∞(X of (equivalence classes of essentially bounded, complex-valued, measurable functions on X is an extremely disconnected compact Hausdorff space.We show, by elementary methods, that the spectrum M of the algebra ℒb(X, ℂ of all bounded measurable functions on X is not extremely disconnected, though totally disconnected. Let ∆ = { δx : x ∈ X} be the set of point evaluations and let g be the Gelfand topology on M. Then (∆, g is homeomorphic to (X, Τdis,where Tdis is the discrete topology. Moreover, ∆ is a dense subset of the spectrum M of ℒb(X, ℂ. Finally, the hull h(I, (which is homeomorphic to M(L∞(X, of the ideal of all functions in ℒb(X, ℂ vanishing almost everywhere on X is a nowhere dense and extremely disconnected subset of the Corona M \\ ∆ of ℒb(X, ℂ.

Improving Pullulanase Catalysis via Reversible Immobilization on Modified Fe3O4@Polydopamine Nanoparticles.

Science.gov (United States)

Wang, Jianfeng; Liu, Zhongmei; Zhou, Zhemin

2017-08-01

To improve the catalysis of pullulanase from Anoxybacillus sp.WB42, Fe 3 O 4 @polydopamine nanoparticles (Fe 3 O 4 @PDA) were prepared and modified with functional groups for immobilization of pullulanases via covalent binding or ionic adsorption. Immobilized pullulanases had lower thermal stability than that of free pullulanase, whereas their catalysis depended on the surface characteristics of nanoparticles. As for covalent immobilization of pullulanases onto Fe 3 O 4 @PDA derivatives, the spacer grafted onto Fe 3 O 4 @PDA made the catalytic efficiency of pullulanase increase up to the equivalence of free enzyme but dramatically reduced the pullulanase thermostability. In contrast, pullulanases bounded ionically to Fe 3 O 4 @PDA derivatives had higher activity recovery and catalytic efficiency, and their catalytic behaviors varied with the modifier grafted onto Fe 3 O 4 @PDA. Among these immobilized pullulanases, ionic adsorption of pullulanase on Fe 3 O 4 @PDA-polyethyleneimine-glycidyltrimethylammonium gave a high-performance and durable catalyst, which displayed not only 1.5-fold increase in catalytic efficiency compared to free enzyme but also a significant improvement in operation stability with a half of initial activity after 27 consecutive cycles with a total reaction time of 13.5 h, and was reversible, making this nanoparticle reusable for immobilization.

Method for assessing the reliability of molecular diagnostics based on multiplexed SERS-coded nanoparticles.

Directory of Open Access Journals (Sweden)

Steven Y Leigh

Full Text Available Surface-enhanced Raman scattering (SERS nanoparticles have been engineered to generate unique fingerprint spectra and are potentially useful as bright contrast agents for molecular diagnostics. One promising strategy for biomedical diagnostics and imaging is to functionalize various particle types ("flavors", each emitting a unique spectral signature, to target a large multiplexed panel of molecular biomarkers. While SERS particles emit narrow spectral features that allow them to be easily separable under ideal conditions, the presence of competing noise sources and background signals such as detector noise, laser background, and autofluorescence confounds the reliability of demultiplexing algorithms. Results obtained during time-constrained in vivo imaging experiments may not be reproducible or accurate. Therefore, our goal is to provide experimentalists with a metric that may be monitored to enforce a desired bound on accuracy within a user-defined confidence level. We have defined a spectral reliability index (SRI, based on the output of a direct classical least-squares (DCLS demultiplexing routine, which provides a measure of the reliability of the computed nanoparticle concentrations and ratios. We present simulations and experiments to demonstrate the feasibility of this strategy, which can potentially be utilized for a range of instruments and biomedical applications involving multiplexed SERS nanoparticles.

ATMP-stabilized iron nanoparticles: chelator-controlled nanoparticle synthesis

Science.gov (United States)

Greenlee, Lauren F.; Rentz, Nikki S.

2014-11-01

In this study, we characterize iron nanoparticles synthesized in water in the presence of a phosphonate chelator, amino tris(methylene phosphonic acid) (ATMP) for a range of molar ratios of ATMP to iron. An increase in the molar ratio from 0.05 to 0.8 decreases nanoparticle size from approximately 150 nm to less than 10 nm. Zeta potential measurements were used to evaluate colloidal stability. Zeta potential values varied as a function of pH, and zeta potential values decreased with increasing pH. At lower molar ratios of ATMP to iron, the zeta potential varied between 15 and -40 mV, passing through an isoelectric point at pH 7.5. At higher ratios, the zeta potential was negative across the measured pH range of 2-12 and varied from -2 to -55 mV. Diffraction analysis indicates that ATMP-stabilized iron nanoparticles may have a nano-crystalline structure, potentially with regions of amorphous iron. Characterization results of ATMP-stabilized iron nanoparticles are compared to results obtained for carboxymethyl cellulose (CMC)-stabilized iron nanoparticles. CMC stabilization caused similar peak broadening in diffraction spectra as for ATMP, suggesting similar nano-crystalline/amorphous structure; however, an increase in the molar ratio of CMC to iron did not cause the same reduction in nanoparticle size as was observed for ATMP-stabilized iron nanoparticles.

Error Bounds: Necessary and Sufficient Conditions

Czech Academy of Sciences Publication Activity Database

Outrata, Jiří; Kruger, A.Y.; Fabian, Marián; Henrion, R.

2010-01-01

Roč. 18, č. 2 (2010), s. 121-149 ISSN 1877-0533 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506; CEZ:AV0Z10190503 Keywords : Error bounds * Calmness * Subdifferential * Slope Subject RIV: BA - General Mathematics Impact factor: 0.333, year: 2010 http://library.utia.cas.cz/separaty/2010/MTR/outrata-error bounds necessary and sufficient conditions.pdf

Intermetallic nanoparticles

Science.gov (United States)

Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

2015-07-14

A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

Amos-type bounds for modified Bessel function ratios☆

Science.gov (United States)

Hornik, Kurt; Grün, Bettina

2013-01-01

We systematically investigate lower and upper bounds for the modified Bessel function ratio Rν=Iν+1/Iν by functions of the form Gα,β(t)=t/(α+t2+β2) in case Rν is positive for all t>0, or equivalently, where ν≥−1 or ν is a negative integer. For ν≥−1, we give an explicit description of the set of lower bounds and show that it has a greatest element. We also characterize the set of upper bounds and its minimal elements. If ν≥−1/2, the minimal elements are tangent to Rν in exactly one point 0≤t≤∞, and have Rν as their lower envelope. We also provide a new family of explicitly computable upper bounds. Finally, if ν is a negative integer, we explicitly describe the sets of lower and upper bounds, and give their greatest and least elements, respectively. PMID:24926105

Amos-type bounds for modified Bessel function ratios.

Science.gov (United States)

Hornik, Kurt; Grün, Bettina

2013-12-01

We systematically investigate lower and upper bounds for the modified Bessel function ratio [Formula: see text] by functions of the form [Formula: see text] in case [Formula: see text] is positive for all [Formula: see text], or equivalently, where [Formula: see text] or [Formula: see text] is a negative integer. For [Formula: see text], we give an explicit description of the set of lower bounds and show that it has a greatest element. We also characterize the set of upper bounds and its minimal elements. If [Formula: see text], the minimal elements are tangent to [Formula: see text] in exactly one point [Formula: see text], and have [Formula: see text] as their lower envelope. We also provide a new family of explicitly computable upper bounds. Finally, if [Formula: see text] is a negative integer, we explicitly describe the sets of lower and upper bounds, and give their greatest and least elements, respectively.

In vivo stem cell tracking with imageable nanoparticles that bind bioorthogonal chemical receptors on the stem cell surface.

Science.gov (United States)

Lee, Sangmin; Yoon, Hwa In; Na, Jin Hee; Jeon, Sangmin; Lim, Seungho; Koo, Heebeom; Han, Sang-Soo; Kang, Sun-Woong; Park, Soon-Jung; Moon, Sung-Hwan; Park, Jae Hyung; Cho, Yong Woo; Kim, Byung-Soo; Kim, Sang Kyoon; Lee, Taekwan; Kim, Dongkyu; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Kim, Kwangmeyung

2017-09-01

It is urgently necessary to develop reliable non-invasive stem cell imaging technology for tracking the in vivo fate of transplanted stem cells in living subjects. Herein, we developed a simple and well controlled stem cell imaging method through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Firstly, the exogenous chemical receptors containing azide (-N 3 ) groups were generated on the surfaces of stem cells through metabolic glycoengineering using metabolic precursor, tetra-acetylated N-azidoacetyl-d-mannosamine(Ac 4 ManNAz). Next, bicyclo[6.1.0]nonyne-modified glycol chitosan nanoparticles (BCN-CNPs) were prepared as imageable nanoparticles to deliver different imaging agents. Cy5.5, iron oxide nanoparticles and gold nanoparticles were conjugated or encapsulated to BCN-CNPs for optical, MR and CT imaging, respectively. These imageable nanoparticles bound chemical receptors on the Ac 4 ManNAz-treated stem cell surface specifically via bioorthogonal copper-free click chemistry. Then they were rapidly taken up by the cell membrane turn-over mechanism resulting in higher endocytic capacity compared non-specific uptake of nanoparticles. During in vivo animal test, BCN-CNP-Cy5.5-labeled stem cells could be continuously tracked by non-invasive optical imaging over 15 days. Furthermore, BCN-CNP-IRON- and BCN-CNP-GOLD-labeled stem cells could be efficiently visualized using in vivo MR and CT imaging demonstrating utility of our stem cell labeling method using chemical receptors. These results conclude that our method based on metabolic glycoengineering and bioorthogonal copper-free click chemistry can stably label stem cells with diverse imageable nanoparticles representing great potential as new stem cell imaging technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

A geometric bound on F-term inflation

NARCIS (Netherlands)

Borghese, Andrea; Roest, Diederik; Zavala, Ivonne

We discuss a general bound on the possibility to realise inflation in any minimal supergravity with F-terms. The derivation crucially depends on the sGoldstini, the scalar field directions that are singled out by spontaneous supersymmetry breaking. The resulting bound involves both slow-roll

Energy conditions bounds and supernovae data

International Nuclear Information System (INIS)

Lima, M.P.; Vitenti, S.D.P.; Reboucas, M.J.

2008-01-01

The energy conditions play an important role in the description of some important properties of the Universe, including the current accelerating expansion phase and the possible recent phase of super-acceleration. In a recent work we have provided a detailed study of the energy conditions for the recent past by deriving bounds from energy conditions and by making the confrontation of the bounds with supernovae data. Here, we extend and update these results in two different ways. First, by carrying out a new statistical analysis for q(z) estimates needed for the confrontation between the bounds and supernovae data. Second, by providing a new picture of the energy conditions fulfillment and violation in the light of the recently compiled Union set of 307 type Ia supernovae and by using two different statistical approaches

Continuous bounded cohomology of locally compact groups

CERN Document Server

2001-01-01

Recent research has repeatedly led to connections between important rigidity questions and bounded cohomology. However, the latter has remained by and large intractable. This monograph introduces the functorial study of the continuous bounded cohomology for topological groups, with coefficients in Banach modules. The powerful techniques of this more general theory have successfully solved a number of the original problems in bounded cohomology. As applications, one obtains, in particular, rigidity results for actions on the circle, for representations on complex hyperbolic spaces and on Teichmüller spaces. A special effort has been made to provide detailed proofs or references in quite some generality.

Research on culture-bound syndromes: new directions.

Science.gov (United States)

Guarnaccia, P J; Rogler, L H

1999-09-01

The unprecedented inclusion of culture-bound syndromes in DSM-IV provides the opportunity for highlighting the need to study such syndromes and the occasion for developing a research agenda to study them. The growing ethnic and cultural diversity of the U.S. population presents a challenge to the mental health field to develop truly cross-cultural approaches to mental health research and services. In this article, the authors provide a critique of previous analyses of the relationship between culture-bound syndromes and psychiatric diagnoses. They highlight the problems in previous classificatory exercises, which tend to focus on subsuming the culture-bound syndromes into psychiatric categories and fail to fully investigate these syndromes on their own terms. A detailed research program based on four key questions is presented both to understand culture-bound syndromes within their cultural context and to analyze the relationship between these syndromes and psychiatric disorders. Results of over a decade of research on ataques de nervios, a Latino-Caribbean cultural syndrome, are used to illustrate this research program. The four questions focus on the nature of the phenomenon, the social-cultural location of sufferers, the relationship of culture-bound syndromes to psychiatric disorders, and the social and psychiatric history of the syndrome in the life course of the sufferer.

Class-specific Error Bounds for Ensemble Classifiers

Energy Technology Data Exchange (ETDEWEB)

Prenger, R; Lemmond, T; Varshney, K; Chen, B; Hanley, W

2009-10-06

The generalization error, or probability of misclassification, of ensemble classifiers has been shown to be bounded above by a function of the mean correlation between the constituent (i.e., base) classifiers and their average strength. This bound suggests that increasing the strength and/or decreasing the correlation of an ensemble's base classifiers may yield improved performance under the assumption of equal error costs. However, this and other existing bounds do not directly address application spaces in which error costs are inherently unequal. For applications involving binary classification, Receiver Operating Characteristic (ROC) curves, performance curves that explicitly trade off false alarms and missed detections, are often utilized to support decision making. To address performance optimization in this context, we have developed a lower bound for the entire ROC curve that can be expressed in terms of the class-specific strength and correlation of the base classifiers. We present empirical analyses demonstrating the efficacy of these bounds in predicting relative classifier performance. In addition, we specify performance regions of the ROC curve that are naturally delineated by the class-specific strengths of the base classifiers and show that each of these regions can be associated with a unique set of guidelines for performance optimization of binary classifiers within unequal error cost regimes.

Lower bounds on Q of some dipole shapes

DEFF Research Database (Denmark)

Kim, Oleksiy S.

2016-01-01

The lower bound on the radiation Q of an arbitrary electrically small antenna shape can be determined by finding the optimal electric current density on the exterior surface of the shape, such that the Q of this current radiating in free space is minimized, and then augmenting it with a magnetic...... current density cancelling the fields inside the shape's surface. The Q of these coupled electric and magnetic currents radiating in free space is the lower bound on Q for the given shape. The approach is exemplified and its general applicability is substantiated by computing the lower bounds...... of spherically capped dipoles and comparing the results to the known bounds of a sphere and a thin cylinder....

Cyclotron transitions of bound ions

Science.gov (United States)

Bezchastnov, Victor G.; Pavlov, George G.

2017-06-01

A charged particle in a magnetic field possesses discrete energy levels associated with particle rotation around the field lines. The radiative transitions between these levels are the well-known cyclotron transitions. We show that a bound complex of particles with a nonzero net charge displays analogous transitions between the states of confined motion of the entire complex in the field. The latter bound-ion cyclotron transitions are affected by a coupling between the collective and internal motions of the complex and, as a result, differ from the transitions of a "reference" bare ion with the same mass and charge. We analyze the cyclotron transitions for complex ions by including the coupling within a rigorous quantum approach. Particular attention is paid to comparison of the transition energies and oscillator strengths to those of the bare ion. Selection rules based on integrals of collective motion are derived for the bound-ion cyclotron transitions analytically, and the perturbation and coupled-channel approaches are developed to study the transitions quantitatively. Representative examples are considered and discussed for positive and negative atomic and cluster ions.

Bounded Rationality, Retaliation, and the Spread of Urban Violence

Science.gov (United States)

Jacobs, Bruce A.; Wright, Richard

2010-01-01

Drawing from in-depth interviews with 52 active street criminals, this article examines the grounded theoretic implications of bounded rationality for retaliatory street violence. The bounds on rationality that this article explores are anger, uncertainty, and time pressure. These bounds create imperfections in the retaliatory decision-making…

Mechanical performance of styrene-butadiene-rubber filled with carbon nanoparticles prepared by mechanical mixing

Energy Technology Data Exchange (ETDEWEB)

Saatchi, M.M. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of); Shojaei, A., E-mail: akbar.shojaei@sharif.edu [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of)

2011-09-15

Highlights: {yields} We compare influence of carbon blacks and carbon nanotube on properties of SBR. {yields} We model mechanical behavior of SBR nanocomposites by the micromechanical model. {yields} Mechanical properties of carbon black/SBR is greatly dominated by bound rubber. {yields} Mechanical properties of SBR/nanotube is governed by big aspect ratio of nanotube. - Abstract: Reinforcement of styrene-butadiene-rubber (SBR) was investigated using two different carbon blacks (CBs) with similar particle sizes, including highly structured CB and conventional CB, as well as multi-walled carbon nanotube (MWCNT) prepared by mechanical mixing. The attempts were made to examine reinforcing mechanism of these two different classes of carbon nanoparticles. Scanning electron microscopy and electrical conductivity measurement were used to investigate morphology. Tensile, cyclic tensile and stress relaxation analyses were performed. A modified Halpin-Tsai model based on the concept of an equivalent composite particle, consisting of rubber bound, occluded rubber and nanoparticle, was proposed. It was found that properties of CB filled SBR are significantly dominated by rubber shell and occluded rubber in which molecular mobility is strictly restricted. At low strains, these rubber constituents can contribute in hydrodynamic effects, leading to higher elastic modulus. However, at higher strains, they contribute in stress hardening resulting in higher elongation at break and higher tensile strength. These elastomeric regions can also influence stress relaxation behaviors of CB filled rubber. For SBR/MWCNT, the extremely great inherent mechanical properties of nanotube along with its big aspect ratio were postulated to be responsible for the reinforcement while their interfacial interaction was not so efficient.

Nanoparticle-based optical biosensors for the direct detection of organophosphate chemical warfare agents and pesticides

International Nuclear Information System (INIS)

Simonian, A.L.; Good, T.A.; Wang, S.-S.; Wild, J.R.

2005-01-01

Neurotoxic organophosphates (OP) have found widespread use in the environment for insect control. In addition, there is the increasing threat of use of OP based chemical warfare agents in both ground based warfare and terrorist attacks. Together, these trends necessitate the development of simple and specific methods for discriminative detection of ultra low quantities of OP neurotoxins. In our previous investigations a new biosensor for the direct detection of organophosphorus neurotoxins was pioneered. In this system, the enzymatic hydrolysis of OP neurotoxins by organophosphate hydrolase (OPH) generated two protons in each hydrolytic turnover through reactions in which P-X bonds are cleaved. The sensitivity of this biosensor was limited due to the potentiometric method of detection. Recently, it was reported that a change in fluorescence properties of a fluorophore in the vicinity of gold nanoparticles might be used for detection of nanomolar concentrations of DNA oligonucleotides. The detection strategy was based on the fact that an enhancement or quenching of fluorescence intensity is a function of the distances between the gold nanoparticle and fluorophore. While these reports have demonstrated the use of nanoparticle-based sensors for the detection of target DNA, we observed that the specificity of enzyme-substrate interactions could be exploited in similar systems. To test the feasibility of this approach, OPH-gold nanoparticle conjugates were prepared, then incubated with a fluorescent enzyme inhibitor or decoy. The fluorescence intensity of the decoy was sensitive to the proximity of the gold nanoparticle, and thus could be used to indicate that the decoy was bound to the OPH. Then different paraoxon concentrations were introduced to the OPH-nanoparticle-conjugate-decoy mixtures, and normalized ratio of fluorescence intensities were measured. The greatest sensitivity to paraoxon was obtained when decoys and OPH-gold nanoparticle conjugates were present at

Bounds on the capacity of constrained two-dimensional codes

DEFF Research Database (Denmark)

Forchhammer, Søren; Justesen, Jørn

2000-01-01

Bounds on the capacity of constrained two-dimensional (2-D) codes are presented. The bounds of Calkin and Wilf apply to first-order symmetric constraints. The bounds are generalized in a weaker form to higher order and nonsymmetric constraints. Results are given for constraints specified by run-l...

Bound entangled states violate a nonsymmetric local uncertainty relation

International Nuclear Information System (INIS)

Hofmann, Holger F.

2003-01-01

As a consequence of having a positive partial transpose, bound entangled states lack many of the properties otherwise associated with entanglement. It is therefore interesting to identify properties that distinguish bound entangled states from separable states. In this paper, it is shown that some bound entangled states violate a nonsymmetric class of local uncertainty relations [H. F. Hofmann and S. Takeuchi, Phys. Rev. A 68, 032103 (2003)]. This result indicates that the asymmetry of nonclassical correlations may be a characteristic feature of bound entanglement

Lower Bounds to the Reliabilities of Factor Score Estimators.

Science.gov (United States)

Hessen, David J

2016-10-06

Under the general common factor model, the reliabilities of factor score estimators might be of more interest than the reliability of the total score (the unweighted sum of item scores). In this paper, lower bounds to the reliabilities of Thurstone's factor score estimators, Bartlett's factor score estimators, and McDonald's factor score estimators are derived and conditions are given under which these lower bounds are equal. The relative performance of the derived lower bounds is studied using classic example data sets. The results show that estimates of the lower bounds to the reliabilities of Thurstone's factor score estimators are greater than or equal to the estimates of the lower bounds to the reliabilities of Bartlett's and McDonald's factor score estimators.

Interactions between macromolecule-bound antioxidants and Trolox during liposome autoxidation

DEFF Research Database (Denmark)

Celik, Ecem Evrim; Amigo Rubio, Jose Manuel; Andersen, Mogens Larsen

2017-01-01

The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively and Tr...... of logistic function was successfully used for modelling the oxidation curve of liposomes. Principal component analysis revealed two separate phases of liposome autoxidation.......The interactions between free and macromolecule-bound antioxidants were investigated in order to evaluate their combined effects on the antioxidant environment. Dietary fiber (DF), protein and lipid-bound antioxidants, obtained from whole wheat, soybean and olive oil products, respectively...... of the simple addition effects of Trolox and bound antioxidants with measured values on lipid oxidation revealed synergetic interactions for DF and refined olive oil-bound antioxidants, and antagonistic interactions for protein and extra virgin olive oil-bound antioxidants with Trolox. A generalized version...

Computationally efficient analytic representations of relativistic bound-bound, bound-unbound and unbound-unbound transition matrix elements of hydrogenic atoms

International Nuclear Information System (INIS)

Soldatov, A.; Seke, J.; Adam, G.; Polak, M.

2008-01-01

Full text: A closed analytic form for relativistic transition matrix elements between bound-bound, bound-unbound and unbound-unbound relativistic eigenstates of hydrogenic atoms by using the plane-wave expansion for the electromagnetic-field vector potential was derived in a form convenient for large-scale numerical calculations in QED. By applying the obtained formulae, these transition matrix elements can be evaluated analytically and numerically. These exact matrix elements, which to our knowledge have not been calculated as yet, are of great importance in the analysis of various atom-field interaction processes where retardation effects cannot be ignored. The ultimate goal of the ongoing research is to develop a general universal calculation technique for Seke's approximation and renormalization method in QED, for which the usage of the plane vector expansion for the vector potential is a preferable choice. However, our primary interest lies in the Lamb-shift calculation. Our nearest objective is to carry out the plain-style relativistic calculations of the Lamb shift of the energy levels of hydrogen-like atoms and ions from first principles in the second and higher perturbative orders, using the corresponding convenient as well as novel expressions for the magnitude in question as they stand, i.e. without any additional approximations. Due to that there is no way to achieve all the above-declared goals without recourse to large-scale laborious and time-consuming high-precision numerical calculations, having the transition matrix elements of all possible types in an analytic, convenient for their efficient numerical evaluation form, would be highly advantageous and even unavoidable, especially for calculations of various QED effects in higher perturbative orders be it, equally, in traditional or novel approach. (author)

Dark-matter bound states from Feynman diagrams

NARCIS (Netherlands)

Petraki, K.; Postma, M.; Wiechers, M.

2015-01-01

If dark matter couples directly to a light force mediator, then it may form bound states in the early universe and in the non-relativistic environment of haloes today. In this work, we establish a field-theoretic framework for the computation of bound-state formation cross-sections, de-excitation

Human Properdin Opsonizes Nanoparticles and Triggers a Potent Pro-inflammatory Response by Macrophages without Involving Complement Activation

Science.gov (United States)

Kouser, Lubna; Paudyal, Basudev; Kaur, Anuvinder; Stenbeck, Gudrun; Jones, Lucy A.; Abozaid, Suhair M.; Stover, Cordula M.; Flahaut, Emmanuel; Sim, Robert B.; Kishore, Uday

2018-01-01

Development of nanoparticles as tissue-specific drug delivery platforms can be considerably influenced by the complement system because of their inherent pro-inflammatory and tumorigenic consequences. The complement activation pathways, and its recognition subcomponents, can modulate clearance of the nanoparticles and subsequent inflammatory response and thus alter the intended translational applications. Here, we report, for the first time, that human properdin, an upregulator of the complement alternative pathway, can opsonize functionalized carbon nanotubes (CNTs) via its thrombospondin type I repeat (TSR) 4 and 5. Binding of properdin and TSR4+5 is likely to involve charge pattern/polarity recognition of the CNT surface since both carboxymethyl cellulose-coated carbon nanotubes (CMC-CNT) and oxidized (Ox-CNT) bound these proteins well. Properdin enhanced the uptake of CMC-CNTs by a macrophage cell line, THP-1, mounting a robust pro-inflammatory immune response, as revealed by qRT-PCR, multiplex cytokine array, and NF-κB nuclear translocation analyses. Properdin can be locally synthesized by immune cells in an inflammatory microenvironment, and thus, its interaction with nanoparticles is of considerable importance. In addition, recombinant TSR4+5 coated on the CMC-CNTs inhibited complement consumption by CMC-CNTs, suggesting that nanoparticle decoration with TSR4+5, can be potentially used as a complement inhibitor in a number of pathological contexts arising due to exaggerated complement activation. PMID:29483907

Bioconjugation of trypsin onto gold nanoparticles: Effect of surface chemistry on bioactivity

Energy Technology Data Exchange (ETDEWEB)

Hinterwirth, Helmut; Lindner, Wolfgang [Department of Analytical Chemistry, University of Vienna, Waehringerstrasse 38, 1090 Vienna (Austria); Laemmerhofer, Michael, E-mail: michael.laemmerhofer@uni-tuebingen.de [Department of Analytical Chemistry, University of Vienna, Waehringerstrasse 38, 1090 Vienna (Austria)

2012-07-06

Highlights: Black-Right-Pointing-Pointer Size and spacer affect bioactivity of nanoparticulate trypsin reactor. Black-Right-Pointing-Pointer Increase of GNP's size increases activity of bound trypsin. Black-Right-Pointing-Pointer Increase of spacer length increases amount and activity of immobilized enzyme by factor 6. Black-Right-Pointing-Pointer Decrease of digestion time up to less than 1 h when trypsin immobilized onto GNPs. Black-Right-Pointing-Pointer Reduced auto-digestion compared to trypsin in-solution. - Abstract: The systematic study of activity, long-time stability and auto-digestion of trypsin immobilized onto gold nanoparticles (GNPs) is described in this paper and compared to trypsin in-solution. Thereby, the influence of GNP's size and immobilization chemistry by various linkers differing in lipophilicity/hydrophilicity and spacer lengths was investigated with regard to the bioactivity of the conjugated enzyme. GNPs with different sizes were prepared by reduction and simultaneous stabilization with trisodium citrate and characterized by UV/vis spectra, dynamic light scattering (DLS), {zeta}-potential measurements and transmission electron microscopy (TEM). GNPs were derivatized by self-assembling of bifunctional thiol reagents on the nanoparticle (NP) surface via dative thiol-gold bond yielding a carboxylic acid functionalized surface. Trypsin was either attached directly via hydrophobic and ionic interactions onto the citrate stabilized GNPs or immobilized via EDC/NHS bioconjugation onto the carboxylic functionalized GNPs, respectively. The amount of bound trypsin was quantified by measuring the absorbance at 280 nm. The activity of bound enzyme and its Michaelis Menten kinetic parameter K{sub m} and v{sub max} were measured by the standard chromogenic substrate N{sub {alpha}}-Benzoyl-DL-arginine 4-nitroanilide hydrochloride (BApNA). Finally, digestion of a standard protein mixture with the trypsin-conjugated NPs followed by analysis with

Bioconjugation of trypsin onto gold nanoparticles: Effect of surface chemistry on bioactivity

International Nuclear Information System (INIS)

Hinterwirth, Helmut; Lindner, Wolfgang; Lämmerhofer, Michael

2012-01-01

Highlights: ► Size and spacer affect bioactivity of nanoparticulate trypsin reactor. ► Increase of GNP's size increases activity of bound trypsin. ► Increase of spacer length increases amount and activity of immobilized enzyme by factor 6. ► Decrease of digestion time up to less than 1 h when trypsin immobilized onto GNPs. ► Reduced auto-digestion compared to trypsin in-solution. - Abstract: The systematic study of activity, long-time stability and auto-digestion of trypsin immobilized onto gold nanoparticles (GNPs) is described in this paper and compared to trypsin in-solution. Thereby, the influence of GNP's size and immobilization chemistry by various linkers differing in lipophilicity/hydrophilicity and spacer lengths was investigated with regard to the bioactivity of the conjugated enzyme. GNPs with different sizes were prepared by reduction and simultaneous stabilization with trisodium citrate and characterized by UV/vis spectra, dynamic light scattering (DLS), ζ-potential measurements and transmission electron microscopy (TEM). GNPs were derivatized by self-assembling of bifunctional thiol reagents on the nanoparticle (NP) surface via dative thiol-gold bond yielding a carboxylic acid functionalized surface. Trypsin was either attached directly via hydrophobic and ionic interactions onto the citrate stabilized GNPs or immobilized via EDC/NHS bioconjugation onto the carboxylic functionalized GNPs, respectively. The amount of bound trypsin was quantified by measuring the absorbance at 280 nm. The activity of bound enzyme and its Michaelis Menten kinetic parameter K m and v max were measured by the standard chromogenic substrate N α -Benzoyl-DL-arginine 4-nitroanilide hydrochloride (BApNA). Finally, digestion of a standard protein mixture with the trypsin-conjugated NPs followed by analysis with LC–ESI-MS and successful MASCOT search demonstrated the applicability of the new heterogenous nano-structured biocatalyst. It could be shown that the

A signal amplification assay for HSV type 1 viral DNA detection using nanoparticles and direct acoustic profiling

Directory of Open Access Journals (Sweden)

Hammond Richard

2010-02-01

Full Text Available Abstract Background Nucleic acid based recognition of viral sequences can be used together with label-free biosensors to provide rapid, accurate confirmation of viral infection. To enhance detection sensitivity, gold nanoparticles can be employed with mass-sensitive acoustic biosensors (such as a quartz crystal microbalance by either hybridising nanoparticle-oligonucleotide conjugates to complimentary surface-immobilised ssDNA probes on the sensor, or by using biotin-tagged target oligonucleotides bound to avidin-modified nanoparticles on the sensor. We have evaluated and refined these signal amplification assays for the detection from specific DNA sequences of Herpes Simplex Virus (HSV type 1 and defined detection limits with a 16.5 MHz fundamental frequency thickness shear mode acoustic biosensor. Results In the study the performance of semi-homogeneous and homogeneous assay formats (suited to rapid, single step tests were evaluated utilising different diameter gold nanoparticles at varying DNA concentrations. Mathematical models were built to understand the effects of mass transport in the flow cell, the binding kinetics of targets to nanoparticles in solution, the packing geometries of targets on the nanoparticle, the packing of nanoparticles on the sensor surface and the effect of surface shear stiffness on the response of the acoustic sensor. This lead to the selection of optimised 15 nm nanoparticles that could be used with a 6 minute total assay time to achieve a limit of detection sensitivity of 5.2 × 10-12 M. Larger diameter nanoparticles gave poorer limits of detection than smaller particles. The limit of detection was three orders of magnitude lower than that observed using a hybridisation assay without nanoparticle signal amplification. Conclusions An analytical model was developed to determine optimal nanoparticle diameter, concentration and probe density, which allowed efficient and rapid optimisation of assay parameters

Water-soluble PEGylated silicon nanoparticles and their assembly into swellable nanoparticle aggregates

International Nuclear Information System (INIS)

Xu, Zejing; Li, Yejia; Zhang, Boyu; Purkait, Tapas; Alb, Alina; Mitchell, Brian S.; Grayson, Scott M.; Fink, Mark J.

2015-01-01

Water-soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water-stable chloroalkyl or alkynyl-terminated nanoparticles, respectively. Nanoparticles with the ω-chloroalkyl substituents were easily converted to ω-azidoalkyl groups through the reaction of the Si nanoparticles with sodium azide in DMF. The azido-terminated nanoparticles were then grafted with mono-alkynyl-PEG polymers using a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core–shell silicon nanoparticles with a covalently attached PEG shell. Covalently linked Si nanoparticle clusters were synthesized via the CuAAC “click” reaction of functional Si NPs with α,ω-functional PEG polymers of various lengths. Dynamic light scattering studies show that the flexible globular nanoparticle aggregates undergo a solvent-dependent change in volume (ethanol > dichloromethane > toluene) similar in behavior to hydrogel nanocomposites

Circumvention of Parker's bound on galactic magnetic monopoles

International Nuclear Information System (INIS)

Dicus, D.A.; Teplitz, V.L.; Maryland Univ., College Park

1983-01-01

There is a possibility that a magnetic monopole has been observed. The monopole density implied by the observation appears to violate bounds on the density of such particles derived from the total mass density of the Universe and from the existence of galactic magnetic fields. It is shown that the observation is not inconsistent with these bounds if the monopoles and antimonopoles are bound into positronium like states with principal quantum n high enough so that the Earth's magnetic field will break them apart, but small enough so that the weaker galactic magnetic field will not. A range of values for n are determined and show that lifetimes for such bound states are longer than the current age of the Universe. (author)

Comparing two reliability upper bounds for multistate systems

International Nuclear Information System (INIS)

Meng, Fan C.

2005-01-01

The path-cut reliability bound due to Esary and Proschan [J. Am. Stat. Assoc. 65 (1970) 329] and the minimax reliability bound due to Barlow and Proschan [Statistical Theory of Reliability and Life Testing: Probability Models, 1981] for binary systems have been generalized to multistate systems by Block and Savits [J. Appl. Probab. 19 (1982) 391]. Some comparison results concerning the two multistate lower bounds for various types of multistate systems are given by Meng [Probab. Eng. Inform. Sci. 16 (2002) 485]. In this note we compare the two multistate upper bounds and present results which generalize some previous ones obtained by Maymin [J. Stat. Plan. Inference 16 (1987) 337] for binary systems. Examples are given to illustrate our results

Finite energy bounds for $\\piN$ scattering

CERN Document Server

Grassberger, P; Schwela, D

1974-01-01

Upper bounds on energy averaged pi N cross sections are given. Using low energy data and data from pi N backward scattering and NN to pi pi annihilation, it is found that sigma /sub tot/bounds are based on assumptions similar to those underlying Froissart's bound and are equal to it asymptotically. However, at finite but large energies, they increase much slower than what might have been anticipated on purely numerological grounds. Related problems in pp and Kp scattering are also discussed. (25 refs) .

Entropic Lower Bound for Distinguishability of Quantum States

Directory of Open Access Journals (Sweden)

Seungho Yang

2015-01-01

Full Text Available For a system randomly prepared in a number of quantum states, we present a lower bound for the distinguishability of the quantum states, that is, the success probability of determining the states in the form of entropy. When the states are all pure, acquiring the entropic lower bound requires only the density operator and the number of the possible states. This entropic bound shows a relation between the von Neumann entropy and the distinguishability.

Entropy Bounds for Constrained Two-Dimensional Fields

DEFF Research Database (Denmark)

Forchhammer, Søren Otto; Justesen, Jørn

1999-01-01

The maximum entropy and thereby the capacity of 2-D fields given by certain constraints on configurations are considered. Upper and lower bounds are derived.......The maximum entropy and thereby the capacity of 2-D fields given by certain constraints on configurations are considered. Upper and lower bounds are derived....

Soft X-ray synchrotron radiation spectroscopy study of molecule-based nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lee, E. S.; Kim, D. H.; Kang, J. S.; Kim, P. [The Catholic University of Korea, Bucheon (Korea, Republic of); Kim, K. H. [Korea University, Jochiwon (Korea, Republic of); Baik, J. Y.; Shin, H. J. [POSTECH, Pohang (Korea, Republic of)

2014-11-15

The electronic structures of molecule-based nanoparticles, such as biomineralized Helicobacter pylori ferritin (Hpf), Heme, and RbCo[Fe(CN){sub 6}]H{sub 2}O (RbCoFe) Prussian blue analogue, have been investigated by employing photoemission spectroscopy and soft X-ray absorption spectroscopy. Fe ions are found to be nearly trivalent in Hpf and Heme nanoparticles, which provides evidence that the amount of magnetite (Fe{sub 3}O{sub 4}) should be negligible in the Hpf core and that the biomineralization of Fe oxides in the high-Fe-bound-state Hpf core arises from a hematite-like formation. On the other hand, Fe ions are nearly divalent and Co ions are Co{sup 2+}-Co{sup 3+} mixed-valent in RbCoFe. Therefore this finding suggests that the mechanism of the photo-induced transition in RbCoFe Prussian blue analogue is not a simple spin-state transition of Fe{sup 2+}-Co{sup 3+} → Fe{sup 3+}-Co{sup 2+}. It is likely that Co{sup 2+} ions have the high-spin configuration while Fe{sup 2+} ions have the low-spin configuration.

Sensitivity Improvement of an Impedimetric Immunosensor Using Functionalized Iron Oxide Nanoparticles

Directory of Open Access Journals (Sweden)

Imen Hafaid

2009-01-01

Full Text Available This work has explored the development of impedimetric immunosensors based on magnetic iron nanoparticles (IrNP functionalized with streptavidin to which a biotinylated FAB part of the antibody has been bound using a biotin-streptavidin interaction. SPR analysis shows a deviation on the measured (angle during antigen-antibody recognition whereas label free detection using by EIS allows us to monitor variation of polarization resistance. Before detection, layers were analyzed by FTIR and AFM. Compared to immobilization of antibody on bare gold surface using aminodecanethiol SAM, antibody immobilization on nanoparticles permitted to reach lower detection limit: 500 pg/ml instead of 1 ng/ml to in the case of EIS and 300 ng/ml instead of 4.5 μg/ml in the case of SPR. Thus, it permitted to improve the sensitivity: from 257.3  Ω⋅cm2⋅μg−1⋅ml to 1871 Ω⋅cm2⋅μg−1⋅ml in the case of EIS and from 0.003°μg−1⋅ml to 0.094°μg−1⋅ml in the case of SPR.

Resistance of soil-bound prions to rumen digestion.

Directory of Open Access Journals (Sweden)

Samuel E Saunders

Full Text Available Before prion uptake and infection can occur in the lower gastrointestinal system, ingested prions are subjected to anaerobic digestion in the rumen of cervids and bovids. The susceptibility of soil-bound prions to rumen digestion has not been evaluated previously. In this study, prions from infectious brain homogenates as well as prions bound to a range of soils and soil minerals were subjected to in vitro rumen digestion, and changes in PrP levels were measured via western blot. Binding to clay appeared to protect noninfectious hamster PrP(c from complete digestion, while both unbound and soil-bound infectious PrP(Sc proved highly resistant to rumen digestion. In addition, no change in intracerebral incubation period was observed following active rumen digestion of unbound hamster HY TME prions and HY TME prions bound to a silty clay loam soil. These results demonstrate that both unbound and soil-bound prions readily survive rumen digestion without a reduction in infectivity, further supporting the potential for soil-mediated transmission of chronic wasting disease (CWD and scrapie in the environment.

Resistance of Soil-Bound Prions to Rumen Digestion

Science.gov (United States)

Saunders, Samuel E.; Bartelt-Hunt, Shannon L.; Bartz, Jason C.

2012-01-01

Before prion uptake and infection can occur in the lower gastrointestinal system, ingested prions are subjected to anaerobic digestion in the rumen of cervids and bovids. The susceptibility of soil-bound prions to rumen digestion has not been evaluated previously. In this study, prions from infectious brain homogenates as well as prions bound to a range of soils and soil minerals were subjected to in vitro rumen digestion, and changes in PrP levels were measured via western blot. Binding to clay appeared to protect noninfectious hamster PrPc from complete digestion, while both unbound and soil-bound infectious PrPSc proved highly resistant to rumen digestion. In addition, no change in intracerebral incubation period was observed following active rumen digestion of unbound hamster HY TME prions and HY TME prions bound to a silty clay loam soil. These results demonstrate that both unbound and soil-bound prions readily survive rumen digestion without a reduction in infectivity, further supporting the potential for soil-mediated transmission of chronic wasting disease (CWD) and scrapie in the environment. PMID:22937149

Lying for the Greater Good: Bounded Rationality in a Team

Directory of Open Access Journals (Sweden)

Oktay Sürücü

2014-10-01

Full Text Available This paper is concerned with the interaction between fully and boundedly rational agents in situations where their interests are perfectly aligned. The cognitive limitations of the boundedly rational agent do not allow him to fully understand the market conditions and lead him to take non-optimal decisions in some situations. Using categorization to model bounded rationality, we show that the fully rational agent can nudge, i.e., he can manipulate the information he sends and decrease the expected loss caused by the boundedly rational agent. Assuming different types for the boundedly rational agent, who differ only in the categories used, we show that the fully rational agent may learn the type of the boundedly rational agent along their interaction. Using this additional information, the outcome can be improved and the amount of manipulated information can be decreased. Furthermore, as the length of the interaction increases the probability that the fully rational agent learns the type of the boundedly rational agent grows

Co-precipitation of oppositely charged nanoparticles: the case of mixed ligand nanoparticles

International Nuclear Information System (INIS)

Moglianetti, Mauro; Ponomarev, Evgeniy; Szybowski, Maxime; Stellacci, Francesco; Reguera, Javier

2015-01-01

Colloid stability is of high importance in a multitude of fields ranging from food science to biotechnology. There is strong interest in studying the stability of small particles (of a size of a few nanometres) with complex surface structures, that make them resemble the complexity of proteins and other natural biomolecules, in the presence of oppositely charged nanoparticles. While for nanoparticles with homogeneously charged surfaces an abrupt precipitation has been observed at the neutrality of charges, data are missing about the stability of nanoparticles when they have more complex surface structures, like the presence of hydrophobic patches. To study the role of these hydrophobic patches in the stability of nanoparticles a series of negatively charged nanoparticles has been synthesized with different ratios of hydrophobic content and with control on the structural distribution of the hydrophobic moiety, and then titrated with positively charged nanoparticles. For nanoparticles with patchy nanodomains, the influence of hydrophobic content was observed together with the influence of the size of the nanoparticles. By contrast, for nanoparticles with a uniform distribution of hydrophobic ligands, size changes and hydrophobic content did not play any role in co-precipitation behaviour. A comparison of these two sets of nanoparticles suggests that nanodomains present at the surfaces of nanoparticles are playing an important role in stability against co-precipitation. (paper)

Nanoparticle mediated micromotor motion

Science.gov (United States)

Liu, Mei; Liu, Limei; Gao, Wenlong; Su, Miaoda; Ge, Ya; Shi, Lili; Zhang, Hui; Dong, Bin; Li, Christopher Y.

2015-03-01

In this paper, we report the utilization of nanoparticles to mediate the motion of a polymer single crystal catalytic micromotor. Micromotors have been fabricated by directly self-assembling functional nanoparticles (platinum and iron oxide nanoparticles) onto one or both sides of two-dimensional polymer single crystals. We show that the moving velocity of these micromotors in fluids can be readily tuned by controlling the nanoparticles' surface wettability and catalytic activity. A 3 times velocity increase has been achieved for a hydrophobic micromotor as opposed to the hydrophilic ones. Furthermore, we demonstrate that the catalytic activity of platinum nanoparticles inside the micromotor can be enhanced by their synergetic interactions with iron oxide nanoparticles and an electric field. Both strategies lead to dramatically increased moving velocities, with the highest value reaching ~200 μm s-1. By decreasing the nanoparticles' surface wettability and increasing their catalytic activity, a maximum of a ~10-fold increase in the moving speed of the nanoparticle based micromotor can be achieved. Our results demonstrate the advantages of using nanoparticles in micromotor systems.In this paper, we report the utilization of nanoparticles to mediate the motion of a polymer single crystal catalytic micromotor. Micromotors have been fabricated by directly self-assembling functional nanoparticles (platinum and iron oxide nanoparticles) onto one or both sides of two-dimensional polymer single crystals. We show that the moving velocity of these micromotors in fluids can be readily tuned by controlling the nanoparticles' surface wettability and catalytic activity. A 3 times velocity increase has been achieved for a hydrophobic micromotor as opposed to the hydrophilic ones. Furthermore, we demonstrate that the catalytic activity of platinum nanoparticles inside the micromotor can be enhanced by their synergetic interactions with iron oxide nanoparticles and an electric

CO 2 Capture Capacity and Swelling Measurements of Liquid-like Nanoparticle Organic Hybrid Materials via Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

KAUST Repository

Park, Youngjune

2012-01-12

Novel nanoparticle organic hybrid materials (NOHMs), which are comprised of organic oligomers or polymers tethered to an inorganic nanosized cores of various sizes, have been synthesized, and their solvating property for CO 2 was investigated using attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. Simultaneous measurements of CO 2 capture capacity and swelling behaviors of polyetheramine (Jeffamine M-2070) and its corresponding NOHMs (NOHM-I-PE2070) were reported at temperatures of (298, 308, 323 and 353) K and CO 2 pressure conditions ranging from (0 to 5.5) MPa. The polymeric canopy, or polymer bound to the nanoparticle surface, showed significantly less swelling behavior with enhanced or comparable CO 2 capture capacity compared to pure unbound polyetheramine. © 2011 American Chemical Society.

Phase I/II dose-finding study of nanoparticle albumin-bound paclitaxel (nab®-Paclitaxel) plus Cisplatin as Treatment for Metastatic Nasopharyngeal Carcinoma

International Nuclear Information System (INIS)

Huang, Yan; Liang, Wenhua; Yang, Yunpeng; Zhao, Liping; Zhao, Hongyun; Wu, Xuan; Zhao, Yuanyuan; Zhang, Yang; Zhang, Li

2016-01-01

This phase I/II study aimed to determine the maximum tolerated dose (MTD) of nanoparticle albumin-bound paclitaxel (nab ® -paclitaxel) plus cisplatin as treatment for metastatic nasopharyngeal carcinoma (NPC). Patients were enrolled into 1 of 3 dose cohorts, each with 21-day treatment cycles: 1) intravenous (IV) nab-paclitaxel 260 mg/m 2 on day 1; 2) IV nab-paclitaxel 140 mg/m 2 on days 1 and 8; 3) IV nab-paclitaxel 100 mg/m 2 on days 1, 8, and 15. All patients received IV cisplatin 75 mg/m 2 on day 1. Treatment continued for 4–6 cycles, or until progression or unacceptable toxicity. If more than one-third of the patients in a cohort experienced a dose-limiting toxicity (DLT), the dose used in the previous cohort would be designated the MTD. Secreted protein acidic and rich in cysteine (SPARC) expression was detected by immunohistochemistry staining. Sixty-nine patients were enrolled, of whom 64 and 67 were eligible for efficacy and safety analysis, respectively. Two DLTs occurred in cohort 1 (grade 4 febrile neutropenia, grade 3 myalgia), none occurred in cohort 2, and 2 occurred in cohort 3 (both grade 3 fatigue). The MTD was not reached. Partial responses were achieved by 42 patients, 15 had stable disease, and 7 had progressive disease, giving an overall response rate of 66 %. Median progression-free survival was 9 months (95 % CI, 6–12 months). Grade ≥ 3 adverse events were mainly hematologic. There was no significant difference between the 3 cohorts with respect to efficacy or safety. Biomarker analyses indicated that stromal, rather than tumoral, SPARC may predict the response to nab-paclitaxel in NPC. Our findings suggest that nab-paclitaxel plus cisplatin is a highly active regimen with moderate toxicity for the treatment of metastatic NPC, which warrants further investigation in a phase III study. ClinicalTrials.gov ID: NCT01735409. The trial was registered on November 20th, 2012. The online version of this article (doi:10.1186/s12885

Molten-droplet synthesis of composite CdSe hollow nanoparticles

KAUST Repository

Gullapalli, Sravani; Grider, Jason M.; Bagaria, Hitesh G.; Lee, Kyusung; Cho, Minjung; Colvin, Vicki L.; Jabbour, Ghassan E.; Wong, Michael

2012-01-01

Many colloidal synthesis routes are not scalable to high production rates, especially for nanoparticles of complex shape or composition, due to precursor expense and hazards, low yields, and the large number of processing steps. The present work describes a strategy to synthesize hollow nanoparticles (HNPs) out of metal chalcogenides, based on the slow heating of a low-melting-point metal salt, an elemental chalcogen, and an alkylammonium surfactant in octadecene solvent. The synthesis and characterization of CdSe HNPs with an outer diameter of 15.6 ± 3.5 nm and a shell thickness of 5.4 ± 0.9 nm are specifically detailed here. The HNP synthesis is proposed to proceed with the formation of alkylammonium-stabilized nano-sized droplets of molten cadmium salt, which then come into contact with dissolved selenium species to form a CdSe shell at the droplet surface. In a reaction-diffusion mechanism similar to the nanoscale Kirkendall effect it is speculated that the cadmium migrates outwardly through this shell to react with more selenium, causing the CdSe shell to thicken. The proposed CdSe HNP structure comprises a polycrystalline CdSe shell coated with a thin layer of amorphous selenium. Photovoltaic device characterization indicates that HNPs have improved electron transport characteristics compared to standard CdSe quantum dots, possibly due to this selenium layer. The HNPs are colloidally stable in organic solvents even though carboxylate, phosphine, and amine ligands are absent; stability is attributed to octadecene-selenide species bound to the particle surface. This scalable synthesis method presents opportunities to generate hollow nanoparticles with increased structural and compositional variety. © 2012 IOP Publishing Ltd.

Molten-droplet synthesis of composite CdSe hollow nanoparticles

KAUST Repository

Gullapalli, Sravani

2012-11-16

Many colloidal synthesis routes are not scalable to high production rates, especially for nanoparticles of complex shape or composition, due to precursor expense and hazards, low yields, and the large number of processing steps. The present work describes a strategy to synthesize hollow nanoparticles (HNPs) out of metal chalcogenides, based on the slow heating of a low-melting-point metal salt, an elemental chalcogen, and an alkylammonium surfactant in octadecene solvent. The synthesis and characterization of CdSe HNPs with an outer diameter of 15.6 ± 3.5 nm and a shell thickness of 5.4 ± 0.9 nm are specifically detailed here. The HNP synthesis is proposed to proceed with the formation of alkylammonium-stabilized nano-sized droplets of molten cadmium salt, which then come into contact with dissolved selenium species to form a CdSe shell at the droplet surface. In a reaction-diffusion mechanism similar to the nanoscale Kirkendall effect it is speculated that the cadmium migrates outwardly through this shell to react with more selenium, causing the CdSe shell to thicken. The proposed CdSe HNP structure comprises a polycrystalline CdSe shell coated with a thin layer of amorphous selenium. Photovoltaic device characterization indicates that HNPs have improved electron transport characteristics compared to standard CdSe quantum dots, possibly due to this selenium layer. The HNPs are colloidally stable in organic solvents even though carboxylate, phosphine, and amine ligands are absent; stability is attributed to octadecene-selenide species bound to the particle surface. This scalable synthesis method presents opportunities to generate hollow nanoparticles with increased structural and compositional variety. © 2012 IOP Publishing Ltd.

Enhancing intracellular taxane delivery: current role and perspectives of nanoparticle albumin-bound paclitaxel in the treatment of advanced breast cancer.

Science.gov (United States)

Guarneri, Valentina; Dieci, Maria Vittoria; Conte, Pierfranco

2012-02-01

Docetaxel and paclitaxel are among the most active agents for the treatment of breast cancer. These first-generation taxanes are extremely hydrophobic; therefore, solvents are needed for its parenteral administration. Albumin nanoparticle technology allows for the transportation of such hydrophobic drugs without the need of potentially toxic solvents. Nab-paclitaxel can be administered without premedication, in a shorter infusion time and without the need for a special infusion set. Moreover, this technology allows the selective delivery of larger amounts of anticancer drug to tumors, by exploiting endogenous albumin pathways. An overview of the albumin nanoparticle technology, from a clinical perspective, is reported in this paper. The preclinical and clinical development of nab-paclitaxel is reviewed, in the context of available therapies for advanced breast cancer, with a focus on safety data. Preclinical and clinical data on the prognostic and predictive role of SPARC (secreted protein, acidic and rich in cysteine) are also reported. Nab-paclitaxel is approved at present for the treatment of metastatic breast cancer, after the failure of first-line standard therapy, when anthracyclines are not indicated. Efficacy and safety data, along with a more convenient administration, confirm the potential for nab-paclitaxel to become a reference taxane in breast cancer treatment.

Bounded dust-acoustic waves in a cylindrically bounded collisional dusty plasma with dust charge variation

International Nuclear Information System (INIS)

Wei Nanxia; Xue Jukui

2006-01-01

Taking into account the boundary, particle collisions, and dust charging effects, dust-acoustic waves in a uniform cylindrically bounded dusty plasma is investigated analytically, and the dispersion relation for the dust-acoustic wave is obtained. The effects of boundary, dust charge variation, particle collision, and dust size on the dust-acoustic wave are discussed in detail. Due to the bounded cylindrical boundary effects, the radial wave number is discrete, i.e., the spectrum is discrete. It is shown that the discrete spectrum, the adiabatic dust charge variation, dust grain size, and the particle collision have significant effects on the dust-acoustic wave

De-alloyed platinum nanoparticles

Science.gov (United States)

Strasser, Peter [Houston, TX; Koh, Shirlaine [Houston, TX; Mani, Prasanna [Houston, TX; Ratndeep, Srivastava [Houston, TX

2011-08-09

A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

Chloroplast protein synthesis: thylakoid bound polysomes synthesize thylakoid proteins

International Nuclear Information System (INIS)

Hurewitz, J.; Jagendorf, A.T.

1986-01-01

Previous work indicated more polysomes bound to pea thylakoids in light than in the dark, in vivo. With isolated intact chloroplasts incubated in darkness, 24 to 74% more RNA was thylakoid-bound at pH 8.3 than at pH 7. Thus the major effect of light in vivo may be due to higher stroma pH. In isolated pea chloroplasts, initiation inhibitors (pactamycin and kanamycin) decreased the extent of RNA binding, and elongation inhibitors (lincomycin and streptomycin) increased it. Thus translation initiation and termination probably control the cycling of bound ribosomes. While only 3 to 6% of total RNA is in bound polysomes the incorporation of 3 H-Leu into thylakoids was proportional to the amount of this bound RNA. When Micrococcal nuclease-treated thylakoids were added to labeled runoff translation products of stroma ribosomes, less than 1% of the label adhered to the added membranes; but 37% of the labeled products made by thylakoid polysomes were bound. These data support the concept that stroma ribosomes are recruited into thylakoid proteins

Synthesis of triangular Au core-Ag shell nanoparticles

International Nuclear Information System (INIS)

Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali

2007-01-01

In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules

Reducing Conservatism of Analytic Transient Response Bounds via Shaping Filters

Science.gov (United States)

Kwan, Aiyueh; Bedrossian, Nazareth; Jan, Jiann-Woei; Grigoriadis, Karolos; Hua, Tuyen (Technical Monitor)

1999-01-01

Recent results show that the peak transient response of a linear system to bounded energy inputs can be computed using the energy-to-peak gain of the system. However, analytically computed peak response bound can be conservative for a class of class bounded energy signals, specifically pulse trains generated from jet firings encountered in space vehicles. In this paper, shaping filters are proposed as a Methodology to reduce the conservatism of peak response analytic bounds. This Methodology was applied to a realistic Space Station assembly operation subject to jet firings. The results indicate that shaping filters indeed reduce the predicted peak response bounds.

Self-Assembled Complexes of Horseradish Peroxidase with Magnetic Nanoparticles Showing Enhanced Peroxidase Activity

KAUST Repository

Corgié, Stéphane C.

2012-02-15

Bio-nanocatalysts (BNCs) consisting of horseradish peroxidase (HRP) self-assembled with magnetic nanoparticles (MNPs) enhance enzymatic activity due to the faster turnover and lower inhibition of the enzyme. The size and magnetization of the MNPs affect the formation of the BNCs, and ultimately control the activity of the bound enzymes. Smaller MNPs form small clusters with a low affinity for the HRP. While the turnover for the bound fraction is drastically increased, there is no difference in the H 2O 2 inhibitory concentration. Larger MNPs with a higher magnetization aggregate in larger clusters and have a higher affinity for the enzyme and a lower substrate inhibition. All of the BNCs are more active than the free enzyme or the MNPs (BNCs > HRP ≤laquo; MNPs). Since the BNCs show surprising resilience in various reaction conditions, they may pave the way towards new hybrid biocatalysts with increased activities and unique catalytic properties for magnetosensitive enzymatic reactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Data on rhizosphere pH, phosphorus uptake and wheat growth responses upon TiO2 nanoparticles application

Directory of Open Access Journals (Sweden)

Rafia Rafique

2018-04-01

Full Text Available In this study, the data sets and analyses provided the information on the characterization of titanium dioxide nanoparticles (TiO2 NPs, and their impacts on rhizosphere pH, and soil-bound phosphorus (P availability to plants together with relevant parameters. For this purpose, wheat (Triticum aestivum L. was cultivated in the TiO2 NPs amended soil over a period of 60 days. After harvesting, the soil and plants were analyzed to examine the rhizosphere pH, P availability in rhizosphere soil, uptake in roots and shoots, biomass produced, chlorophyll content and translocation to different plant parts monitored by SEM and EDX techniques in response to different dosages of TiO2 NPs. The strong relationship can be found among TiO2 NPs application, P availability, and plant growth. Keywords: Rhizosphere pH, TiO2 NPs nanoparticles, Wheat, Phosphorus, Uptake

On the range of completely bounded maps

Directory of Open Access Journals (Sweden)

Richard I. Loebl

1978-01-01

Full Text Available It is shown that if every bounded linear map from a C*-algebra α to a von Neumann algebra β is completely bounded, then either α is finite-dimensional or β⫅⊗Mn, where is a commutative von Neumann algebra and Mn is the algebra of n×n complex matrices.

Experimental evidence for bounds on quantum correlations.

Science.gov (United States)

Bovino, F A; Castagnoli, G; Degiovanni, I P; Castelletto, S

2004-02-13

We implemented the experiment proposed by Cabello in the preceding Letter to test the bounds of quantum correlation. As expected from the theory we found that, for certain choices of local observables, Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality (2 x square root of 2) is not reached by any quantum states.

Bound water in Kevlar 49 fibers

International Nuclear Information System (INIS)

Garza, R.G.; Pruneda, C.O.; Morgan, R.J.

1981-01-01

From elemental analyses, thermogravimetric-mass spectroscopy studies and re-evaluation of previous water diffusion studies in Kevlar 49 fibers it is concluded that these fibers can contain two types of sorbed moisture. The fibers can absorb up to approx. 6 wt % loosely bound water with an activation energy for outgassing by desorption of 6 kcal/mole. This loosely bound water is a direct result of the presence of Na 2 SO 4 impurities and the perturbations they induce on the packing of the rod-like poly (p-phenylene terephthalamide) macromolecules. Kevlar 49 fibers also inherently contain up to 30 wt % additional water which is tightly bound within the crystal lattice. This water exhibits an activation energy for outgassing by diffusion of approx. 40 kcal/mole and is only evolved from the fiber in significant quantities at t > 350 0 C over a period of hours

On the Applicability of Lower Bounds for Solving Rectilinear

DEFF Research Database (Denmark)

Clausen, Jens; Karisch, Stefan E.; Perregaard, M.

1998-01-01

. Recently, lower bounds based on decomposition were proposed for the so called rectilinear QAP that proved to be the strongest for a large class of problem instances. We investigate the strength of these bounds when applied not only at the root node of a search tree but as the bound function used......The quadratic assignment problem (QAP) belongs to the hard core of NP-hard optimization problems. After almost forty years of research only relatively small instances can be solved to optimality. The reason is that the quality of the lower bounds available for exact methods is not sufficient...

Upper bounds on quantum uncertainty products and complexity measures

Energy Technology Data Exchange (ETDEWEB)

Guerrero, Angel; Sanchez-Moreno, Pablo; Dehesa, Jesus S. [Department of Atomic, Molecular and Nuclear Physics, University of Granada, Granada (Spain); Department of Applied Mathematics, University of Granada, Granada (Spain) and Institute Carlos I for Computational and Theoretical Physics, University of Granada, Granada (Spain); Department of Atomic, Molecular and Nuclear Physics, University of Granada, Granada (Spain); Institute Carlos I for Computational and Theoretical Physics, University of Granada, Granada (Spain)

2011-10-15

The position-momentum Shannon and Renyi uncertainty products of general quantum systems are shown to be bounded not only from below (through the known uncertainty relations), but also from above in terms of the Heisenberg-Kennard product . Moreover, the Cramer-Rao, Fisher-Shannon, and Lopez-Ruiz, Mancini, and Calbet shape measures of complexity (whose lower bounds have been recently found) are also bounded from above. The improvement of these bounds for systems subject to spherically symmetric potentials is also explicitly given. Finally, applications to hydrogenic and oscillator-like systems are done.

Bounded Perturbation Regularization for Linear Least Squares Estimation

KAUST Repository

Ballal, Tarig; Suliman, Mohamed Abdalla Elhag; Al-Naffouri, Tareq Y.

2017-01-01

This paper addresses the problem of selecting the regularization parameter for linear least-squares estimation. We propose a new technique called bounded perturbation regularization (BPR). In the proposed BPR method, a perturbation with a bounded

Intelligent hydrophilic nanoparticles fabricated via alkaline hydrolysis of crosslinked polyacrylonitrile nanoparticles

International Nuclear Information System (INIS)

Zhang, Y.; Wu, Q.; Zhang, H.; Zhao, J.

2013-01-01

Crosslinked polyacrylonitrile (PAN) nanolatex, with an average hydrodynamic diameter of 84 nm and a polydispersity index of 0.06, was successfully synthesized at a high monomer concentration and low surfactant content via a modified emulsion polymerization. Three measurements were adopted to control the nucleation and growth processes. Taking advantage of the chemical activity of nitrile groups, intelligent hydrophilic polymeric nanoparticles were fabricated via simple alkaline hydrolysis treatment of the crosslinked PAN nanolatex. Dynamic light scattering, electrophoretic light scattering, FT-IR spectroscopy, elemental analysis, and TEM observations were used to monitor the changes in the composition, structure, and morphology of the nanoparticles during the hydrolysis process. The sizes, chemical composition, morphology, and pH-responsive behavior of the intelligent hydrophilic nanoparticles could be adjusted by simply changing the hydrolysis time. As the hydrolysis was prolonged, the following nanoparticles could be obtained, crosslinked PAN nanoparticles with hydrophilic surfaces, amphiphilic nanoparticles with a hydrophobic PAN core and a hydrophilic polymeric shell composed of acrylamide and acrylic acid units, or carboxylic polyacrylamide nanoparticles. These modified nanoparticles all display good hydrophilicity, good biocompatibility, pH-sensitivity, as well as carboxyl functional groups, and thus are ideal candidates for various biomedical applications

Intelligent hydrophilic nanoparticles fabricated via alkaline hydrolysis of crosslinked polyacrylonitrile nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Zhang, Y., E-mail: zhyw@dhu.edu.cn; Wu, Q.; Zhang, H.; Zhao, J. [Donghua University, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Chemical Fibers Research Institute (China)

2013-07-15

Crosslinked polyacrylonitrile (PAN) nanolatex, with an average hydrodynamic diameter of 84 nm and a polydispersity index of 0.06, was successfully synthesized at a high monomer concentration and low surfactant content via a modified emulsion polymerization. Three measurements were adopted to control the nucleation and growth processes. Taking advantage of the chemical activity of nitrile groups, intelligent hydrophilic polymeric nanoparticles were fabricated via simple alkaline hydrolysis treatment of the crosslinked PAN nanolatex. Dynamic light scattering, electrophoretic light scattering, FT-IR spectroscopy, elemental analysis, and TEM observations were used to monitor the changes in the composition, structure, and morphology of the nanoparticles during the hydrolysis process. The sizes, chemical composition, morphology, and pH-responsive behavior of the intelligent hydrophilic nanoparticles could be adjusted by simply changing the hydrolysis time. As the hydrolysis was prolonged, the following nanoparticles could be obtained, crosslinked PAN nanoparticles with hydrophilic surfaces, amphiphilic nanoparticles with a hydrophobic PAN core and a hydrophilic polymeric shell composed of acrylamide and acrylic acid units, or carboxylic polyacrylamide nanoparticles. These modified nanoparticles all display good hydrophilicity, good biocompatibility, pH-sensitivity, as well as carboxyl functional groups, and thus are ideal candidates for various biomedical applications.

Lower bounds on scintillation detector timing performance

International Nuclear Information System (INIS)

Clinthorne, N.H.; Rogers, W.L.; Hero, A.O. III.; Petrick, N.A.

1990-01-01

Fundamental method-independent limits on the timing performance of scintillation detectors are useful for identifying regimes in which either present timing methods are nearly optimal or where a considerable performance gain might be realized using better pulse processing techniques. Several types of lower bounds on mean-squared timing error (MSE) performance have been developed and applied to scintillation detectors. The simple Cramer-Rao (CR) bound can be useful in determining the limiting MSE for scintillators having a relatively high rate of photon problction such as BaF 2 and NaI(Tl); however, it tends to overestimate the achievalbe performance for scintillators with lower rates such as BGO. For this reason, alternative bounds have been developed using rate-distortion theory or by assuming that the conversion of energy to scintillation light must pass through excited states which have exponential lifetime densities. The bounds are functions of the mean scintillation pulse shape, the scintillation intensity, and photodetector characteristics; they are simple to evaluate and can be used to conveniently assess the limiting timing performance of scintillation detectors. (orig.)

Mitoxantrone Loaded Superparamagnetic Nanoparticles for Drug Targeting: A Versatile and Sensitive Method for Quantification of Drug Enrichment in Rabbit Tissues Using HPLC-UV

Directory of Open Access Journals (Sweden)

Rainer Tietze

2010-01-01

Full Text Available In medicine, superparamagnetic nanoparticles bound to chemotherapeutics are currently investigated for their feasibility in local tumor therapy. After intraarterial application, these particles can be accumulated in the targeted area by an external magnetic field to increase the drug concentration in the region of interest (Magnetic-Drug-Targeting. We here present an analytical method (HPLC-UV, to detect pure or ferrofluid-bound mitoxantrone in a complex matrix even in trace amounts in order to perform biodistribution studies. Mitoxantrone could be extracted in high yields from different tissues. Recovery of mitoxantrone in liver tissue (5000 ng/g was 76±2%. The limit of quantification of mitoxantrone standard was 10 ng/mL ±12%. Validation criteria such as linearity, precision, and stability were evaluated in ranges achieving the FDA requirements. As shown for pilot samples, biodistribution studies can easily be performed after application of pure or ferrofluid-bound mitoxantrone.

Cosmological implications of Dark Matter bound states

Energy Technology Data Exchange (ETDEWEB)

Mitridate, Andrea [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126, Pisa (Italy); Redi, Michele; Smirnov, Juri [INFN, Sezione di Firenze, and Dipartimento di Fisica e Astronomia, Università di Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino (Italy); Strumia, Alessandro, E-mail: andrea.mitridate@gmail.com, E-mail: michele.redi@fi.infn.it, E-mail: juri.smirnov@mpi-hd.mpg.de, E-mail: alessandro.strumia@cern.ch [Dipartimento di Fisica dell' Università di Pisa and INFN, Pisa (Italy)

2017-05-01

We present generic formulæ for computing how Sommerfeld corrections together with bound-state formation affects the thermal abundance of Dark Matter with non-abelian gauge interactions. We consider DM as a fermion 3plet (wino) or 5plet under SU(2) {sub L} . In the latter case bound states raise to 11.5 TeV the DM mass required to reproduce the cosmological DM abundance and give indirect detection signals such as (for this mass) a dominant γ-line around 70 GeV. Furthermore, we consider DM co-annihilating with a colored particle, such as a squark or a gluino, finding that bound state effects are especially relevant in the latter case.

A nanoparticle in plasma

International Nuclear Information System (INIS)

Martynenko, Yu. V.; Nagel', M. Yu.; Orlov, M. A.

2009-01-01

Charge and energy fluxes onto a nanoparticle under conditions typical of laboratory plasmas are investigated theoretically. Here, by a nanoparticle is meant a grain the size of which is much smaller than both the electron Larmor radius and Debye length and the thermionic emission from which is not limited by the space charge. Under conditions at which thermionic emission plays an important role, the electric potential and temperature T p of a nanoparticle are determined by solving a self-consistent set of equations describing the balance of energy and charge fluxes onto the nanoparticle. It is shown that, when the degree of plasma ionization exceeds a critical level, the potential of the nanoparticle and the energy flux onto it increase with increasing nanoparticle temperature, so that, starting from a certain temperature, the nanoparticle potential becomes positive. The critical degree of ionization starting from which the potential of a nanoparticle is always positive is determined as a function of the plasma density and electron temperature. The nanoparticle temperature T p corresponding to the equilibrium state of a positively charged nanoparticle is found as a function of the electron density for different electron temperatures.

Surface chemistry of gold nanoparticles determines the biocorona composition impacting cellular uptake, toxicity and gene expression profiles in human endothelial cells.

Science.gov (United States)

Chandran, Parwathy; Riviere, Jim E; Monteiro-Riviere, Nancy A

2017-05-01

This study investigated the role of nanoparticle size and surface chemistry on biocorona composition and its effect on uptake, toxicity and cellular responses in human umbilical vein endothelial cells (HUVEC), employing 40 and 80 nm gold nanoparticles (AuNP) with branched polyethyleneimine (BPEI), lipoic acid (LA) and polyethylene glycol (PEG) coatings. Proteomic analysis identified 59 hard corona proteins among the various AuNP, revealing largely surface chemistry-dependent signature adsorbomes exhibiting human serum albumin (HSA) abundance. Size distribution analysis revealed the relative instability and aggregation inducing potential of bare and corona-bound BPEI-AuNP, over LA- and PEG-AuNP. Circular dichroism analysis showed surface chemistry-dependent conformational changes of proteins binding to AuNP. Time-dependent uptake of bare, plasma corona (PC) and HSA corona-bound AuNP (HSA-AuNP) showed significant reduction in uptake with PC formation. Cell viability studies demonstrated dose-dependent toxicity of BPEI-AuNP. Transcriptional profiling studies revealed 126 genes, from 13 biological pathways, to be differentially regulated by 40 nm bare and PC-bound BPEI-AuNP (PC-BPEI-AuNP). Furthermore, PC formation relieved the toxicity of cationic BPEI-AuNP by modulating expression of genes involved in DNA damage and repair, heat shock response, mitochondrial energy metabolism, oxidative stress and antioxidant response, and ER stress and unfolded protein response cascades, which were aberrantly expressed in bare BPEI-AuNP-treated cells. NP surface chemistry is shown to play the dominant role over size in determining the biocorona composition, which in turn modulates cell uptake, and biological responses, consequently defining the potential safety and efficacy of nanoformulations.

Fast concurrent array-based stacks, queues and deques using fetch-and-increment-bounded, fetch-and-decrement-bounded and store-on-twin synchronization primitives

Science.gov (United States)

Chen, Dong; Gara, Alana; Heidelberger, Philip; Kumar, Sameer; Ohmacht, Martin; Steinmacher-Burow, Burkhard; Wisniewski, Robert

2014-09-16

Implementation primitives for concurrent array-based stacks, queues, double-ended queues (deques) and wrapped deques are provided. In one aspect, each element of the stack, queue, deque or wrapped deque data structure has its own ticket lock, allowing multiple threads to concurrently use multiple elements of the data structure and thus achieving high performance. In another aspect, new synchronization primitives FetchAndIncrementBounded (Counter, Bound) and FetchAndDecrementBounded (Counter, Bound) are implemented. These primitives can be implemented in hardware and thus promise a very fast throughput for queues, stacks and double-ended queues.

Functional Magnetic Nanoparticles

Science.gov (United States)

Gass, James

Nanoparticle system research and characterization is the focal point of this research and dissertation. In the research presented here, magnetite, cobalt, and ferrite nanoparticle systems have been explored in regard to their magnetocaloric effect (MCE) properties, as well as for use in polymer composites. Both areas of study have potential applications across a wide variety of interdisciplinary fields. Magnetite nanoparticles have been successfully dispersed in a polymer. The surface chemistry of the magnetic nanoparticle proves critical to obtaining a homogenous and well separated high density dispersion in PMMA. Theoretical studies found in the literature have indicated that surface interface energy is a critical component in dispersion. Oleic acid is used to alter the surface of magnetite nanoparticles and successfully achieve good dispersion in a PMMA thin film. Polypyrrole is then coated onto the PMMA composite layer. The bilayer is characterized using cross-sectional TEM, cross-sectional SEM, magnetic characterization, and low frequency conductivity. The results show that the superparmagnetic properties of the as synthesized particles are maintained in the composite. With further study of the properties of these nanoparticles for real and functional uses, MCE is studied on a variety of magnetic nanoparticle systems. Magnetite, manganese zinc ferrite, and cobalt ferrite systems show significant broadening of the MCE and the ability to tune the peak temperature of MCE by varying the size of the nanoparticles. Four distinct systems are studied including cobalt, cobalt core silver shell nanoparticles, nickel ferrite, and ball milled zinc ferrite. The results demonstrate the importance of surface characteristics on MCE. Surface spin disorder appears to have a large influence on the low temperature magnetic and magnetocalorie characteristics of these nanoparticle systems.

Synthesis and Characterization of BSA Conjugated Silver Nanoparticles (Ag/BSA Nanoparticles) and Evaluation of Biological Properties of Ag/BSA Nanoparticles and Ag/BSA Nanoparticles Loaded Poly(hydroxy butyrate valerate) PHBV Films

Science.gov (United States)

Ambaye, Almaz

Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa are the etiological agents of several infectious diseases. Antibiotic resistance by these three microbes has emerged as a prevalent problem due in part to the misuse of existing antibiotics and the lack of novel antibiotics. Nanoparticles have emerged as an alternative antibacterial agents to conventional antibiotics owing to their high surface area to volume ratio and their unique chemical and physical properties. Among the nanoparticles, silver nanoparticles have gained increasing attention because silver nanoparticles exhibit antibacterial activity against a range of gram positive and gram negative bacteria. Nanoparticles of well-defined chemistry and morphology can be used in broad biomedical applications, especially in bone tissue engineering applications, where bone infection by bacteria can be acute and lethal. It is commonly noted in the literature that the activity of nanoparticles against microorganisms is dependent upon the size and concentration of the nanoparticles as well as the chemistry of stabilizing agent. To the best of our knowledge, a comprehensive study that evaluates the antibacterial activity of well characterized silver nanoparticles in particular Bovine Serum Albumin (BSA) stabilized against S. aureus and E. coli and cytotoxicity level of BSA stabilized silver nanoparticles towards osteoblast cells (MC3T3-E1) is currently lacking. Therefore, the primary objective of this study was to characterize protein conjugated silver nanoparticles prepared by chemical reduction of AgNO3 and BSA mixture. The formation of Ag/BSA nanoparticles was studied by UV-Vis spectroscopy. The molar ratio of silver to BSA in the Ag/BSA nanoparticles was established to be 27+/- 3: 1, based on Thermogravimetric Analysis and Atomic Absorption Spectroscopy. Based on atomic force microscopy, dynamic light scattering,and transmission electron microscopy(TEM) measurements, the particle size (diameter) of

Cosmological stability bound in massive gravity and bigravity

International Nuclear Information System (INIS)

Fasiello, Matteo; Tolley, Andrew J.

2013-01-01

We give a simple derivation of a cosmological bound on the graviton mass for spatially flat FRW solutions in massive gravity with an FRW reference metric and for bigravity theories. This bound comes from the requirement that the kinetic term of the helicity zero mode of the graviton is positive definite. The bound is dependent only on the parameters in the massive gravity potential and the Hubble expansion rate for the two metrics. We derive the decoupling limit of bigravity and FRW massive gravity, and use this to give an independent derivation of the cosmological bound. We recover our previous results that the tension between satisfying the Friedmann equation and the cosmological bound is sufficient to rule out all observationally relevant FRW solutions for massive gravity with an FRW reference metric. In contrast, in bigravity this tension is resolved due to different nature of the Vainshtein mechanism. We find that in bigravity theories there exists an FRW solution with late-time self-acceleration for which the kinetic terms for the helicity-2, helicity-1 and helicity-0 are generically nonzero and positive making this a compelling candidate for a model of cosmic acceleration. We confirm that the generalized bound is saturated for the candidate partially massless (bi)gravity theories but the existence of helicity-1/helicity-0 interactions implies the absence of the conjectured partially massless symmetry for both massive gravity and bigravity

On Landauer's Principle and Bound for Infinite Systems

Science.gov (United States)

Longo, Roberto

2018-04-01

Landauer's principle provides a link between Shannon's information entropy and Clausius' thermodynamical entropy. Here we set up a basic formula for the incremental free energy of a quantum channel, possibly relative to infinite systems, naturally arising by an Operator Algebraic point of view. By the Tomita-Takesaki modular theory, we can indeed describe a canonical evolution associated with a quantum channel state transfer. Such evolution is implemented both by a modular Hamiltonian and a physical Hamiltonian, the latter being determined by its functoriality properties. This allows us to make an intrinsic analysis, extending our QFT index formula, but without any a priori given dynamics; the associated incremental free energy is related to the logarithm of the Jones index and is thus quantised. This leads to a general lower bound for the incremental free energy of an irreversible quantum channel which is half of the Landauer bound, and to further bounds corresponding to the discrete series of the Jones index. In the finite dimensional context, or in the case of DHR charges in QFT, where the dimension is a positive integer, our lower bound agrees with Landauer's bound.

Rare Earth Oxide Fluoride Nanoparticles And Hydrothermal Method For Forming Nanoparticles

Science.gov (United States)

Fulton, John L.; Hoffmann, Markus M.

2003-12-23

A hydrothermal method for forming nanoparticles of a rare earth element, oxygen and fluorine has been discovered. Nanoparticles comprising a rare earth element, oxygen and fluorine are also described. These nanoparticles can exhibit excellent refractory properties as well as remarkable stability in hydrothermal conditions. The nanoparticles can exhibit excellent properties for numerous applications including fiber reinforcement of ceramic composites, catalyst supports, and corrosion resistant coatings for high-temperature aqueous solutions.

Microscopic observation of magnon bound states and their dynamics.

Science.gov (United States)

Fukuhara, Takeshi; Schauß, Peter; Endres, Manuel; Hild, Sebastian; Cheneau, Marc; Bloch, Immanuel; Gross, Christian

2013-10-03

The existence of bound states of elementary spin waves (magnons) in one-dimensional quantum magnets was predicted almost 80 years ago. Identifying signatures of magnon bound states has so far remained the subject of intense theoretical research, and their detection has proved challenging for experiments. Ultracold atoms offer an ideal setting in which to find such bound states by tracking the spin dynamics with single-spin and single-site resolution following a local excitation. Here we use in situ correlation measurements to observe two-magnon bound states directly in a one-dimensional Heisenberg spin chain comprising ultracold bosonic atoms in an optical lattice. We observe the quantum dynamics of free and bound magnon states through time-resolved measurements of two spin impurities. The increased effective mass of the compound magnon state results in slower spin dynamics as compared to single-magnon excitations. We also determine the decay time of bound magnons, which is probably limited by scattering on thermal fluctuations in the system. Our results provide a new way of studying fundamental properties of quantum magnets and, more generally, properties of interacting impurities in quantum many-body systems.

Bounds and estimates for the linearly perturbed eigenvalue problem

International Nuclear Information System (INIS)

Raddatz, W.D.

1983-01-01

This thesis considers the problem of bounding and estimating the discrete portion of the spectrum of a linearly perturbed self-adjoint operator, M(x). It is supposed that one knows an incomplete set of data consisting in the first few coefficients of the Taylor series expansions of one or more of the eigenvalues of M(x) about x = 0. The foundations of the variational study of eigen-values are first presented. These are then used to construct the best possible upper bounds and estimates using various sets of given information. Lower bounds are obtained by estimating the error in the upper bounds. The extension of these bounds and estimates to the eigenvalues of the doubly-perturbed operator M(x,y) is discussed. The results presented have numerous practical application in the physical sciences, including problems in atomic physics and the theory of vibrations of acoustical and mechanical systems

Bounds on the pomeron intercept from accelerator data

International Nuclear Information System (INIS)

Luna, E.G.S.; Menon, M.J.

2002-01-01

Taking into account the discrepancies in the pp and p-bar p total cross section data at √8 = 1.8 TeV, we estimate upper and lower bounds for the soft pomeron intercept. We make use of the Donnachie-Landshoff parameterization for the total cross section and derivative analyticity relations in order to calculate the ρ parameter. Individual and global fits to these quantities and tests with the subtraction constant allow to infer α IP (0) = 1.092 as upper bound and α IP (0) = 1.077 as lower bound. (author)

Effect of nanoparticles as lubricant additives on friction and wear behavior of tetrahedral amorphous carbon (ta-C coating

Directory of Open Access Journals (Sweden)

Xiang Li

2018-03-01

Full Text Available As diamond like carbon (DLC coating becomes increasingly popular in providing low friction and wear under lubricated conditions, the effect of various oil additives on tribological behavior of DLC coating is drawing more attention. Various oil additives, such as ZnDTP and MoDTC, have been widely used in automobile engine industry to pursuit excellent tribological performance in the insufficient lubrication condition. Although such commercial oil additives have been proven to reduce friction or/and wear to some extent, usage of such high -SAPS (sulphuric ash, phosphor, sulfphur conventional additives is bound to arouse concerns due to environmental reasons. In this research, we investigate the effect of two nanoparticle oil additives, which are cerium oxide (CeO2 and zirconium dioxide (ZrO2, on friction and wear of non-hydrogen tetrahedral amorphous carbon (ta-C coating. The results show that by adding ZrO2 nanoparticle, the friction of DLC coating could be reduced about 32% compared to non-additive base oil scenario, but specific wear rate increases by 40%. When CeO2 nanoparticle is used, friction increases by 22% compared to non-additive base oil scenario, however wear decreases by nearly 77%.

Charged boson bound states in the kerr-newman metric

International Nuclear Information System (INIS)

Li Yuanjie; Zhang Duanming

1986-01-01

Charged boson bound states in Kerr-Newman metric are discussed. It is found that massless boson cannot be attracted by Kerr-Newman black hole to form bound states. For the massive boson, the condition of the nonbound states when 0 2 - Q 2 and both the condition and wave functions of the bound states when a = √M 2 - Q 2 are obtained. The energy mode of the bound states is single, E = (m√M 2 - Q 2 + eQM)/(2M 2 - Q 2 ). When Q = 0 or e = 0, the conclusion is in agreement with that of Zhang Shiwei and Su Rukeng

Analysis of the organically bound tritium

International Nuclear Information System (INIS)

Baglan, N.; Alanic, G.

2011-01-01

In environmental samples, tritium is very often combined with the fraction of bulk water accumulated in the sample but also in the form of organically bound tritium. When the tritium is organically bound, 2 forms can coexist: the exchangeable fraction and the non-exchangeable fraction. The analysis of the different forms of tritium present in the sample is necessary to assess the sanitary hazards due to tritium. The total tritium is obtained from the analysis of the water released when the fresh sample is burnt while the organically bound tritium is obtained from the analysis of the water released when the dry extract of the sample is burnt. The measurement of the exchangeable fraction and the non-exchangeable fraction requires an additional stage of labile exchange. The exchangeable fraction is determined from the analysis of the water released during the labile exchange and the non-exchangeable fraction is determined from the water released during the combustion of the dry extract of the labile exchange

Search for quasi bound η mesons

International Nuclear Information System (INIS)

Machner, H

2015-01-01

The search for a quasi bound η meson in atomic nuclei is reviewed. This tentative state is studied theoretically as well as experimentally. The theory starts from elastic η nucleon scattering which is derived from production data within some models. From this interaction the η nucleus interaction is derived. Model calculations predict binding energies and widths of the quasi bound state. Another method is to derive the η nucleus interaction from excitation functions of η production experiments. The s wave interaction is extracted from such data via final state interaction (FSI) theorem. We give the derivation of s wave amplitudes in partial wave expansion and in helicity amplitudes and their relation to observables. Different experiments extracting the FSI are discussed as are production experiments. So far only three experiments give evidence for the existence of the quasi bound state: a pion double charge exchange experiment, an effective mass measurement, and a transfer reaction at recoil free kinematics with observation of the decay of the state. (topical review)

On an extension of the space of bounded deformations

Czech Academy of Sciences Publication Activity Database

Kružík, Martin; Zimmer, J.

2012-01-01

Roč. 31, č. 1 (2012), s. 75-91 ISSN 0232-2064 R&D Projects: GA AV ČR IAA100750802 Institutional research plan: CEZ:AV0Z10750506 Keywords : Bounded sequences of symmetrised gradients * bounded deformation Subject RIV: BA - General Mathematics Impact factor: 0.620, year: 2012 http://library.utia.cas.cz/separaty/2012/MTR/kruzik-on an extension of the space of bounded deformations.pdf

Testing and using the Lewin-Lieb bounds in density functional theory

Science.gov (United States)

Feinblum, David; Kenison, John; Burke, Kieron

Lewin and Lieb have recently proven several new bounds on the exchange-correlation energy that complement the Lieb-Oxford bound. We test these bounds for atoms, for slowly-varying gases, and for Hooke's atom, finding them usually less strict than the Lieb-Oxford bound. However, we also show that, if a generalized gradient approximation (GGA) is to guarantee satisfaction of the new bounds for all densities, new restrictions on the the exchange-correlation enhancement factor are implied. We thank Mathieu Lewin and Elliott Lieb for bringing their new bounds to our attention, and Eberhard Engel for developing the OPMKS atom code. This work was supported by NSF under Grant CHE-1112442.

The linear programming bound for binary linear codes

NARCIS (Netherlands)

Brouwer, A.E.

1993-01-01

Combining Delsarte's (1973) linear programming bound with the information that certain weights cannot occur, new upper bounds for dmin (n,k), the maximum possible minimum distance of a binary linear code with given word length n and dimension k, are derived.

Controlled synthesis of PbS-Au nanostar-nanoparticle heterodimers and cap-like Au nanoparticles

Science.gov (United States)

Zhao, Nana; Li, Lianshan; Huang, Teng; Qi, Limin

2010-11-01

Uniform PbS-Au nanostar-nanoparticle heterodimers consisting of one Au nanoparticle grown on one horn of a well-defined six-horn PbS nanostar were prepared using the PbS nanostars as growth substrates for the selective deposition of Au nanoparticles. The size of the Au nanoparticles on the horns of the PbS nanostars could be readily adjusted by changing the PbS concentration for the deposition of Au nanoparticles. An optimum cetyltrimethylammonium bromide concentration and temperature were essential for the selective deposition of uniform Au nanoparticles on single horns of the PbS nanostars. Unusual PbS-Au nanoframe-nanoparticle heterodimers were obtained by etching the PbS-Au nanostar-nanoparticle heterodimers with oxalic acid while novel cap-like Au nanoparticles were obtained by etching with hydrochloric acid. The obtained heterodimeric nanostructures and cap-like nanoparticles are promising candidates for anisotropic nanoscale building blocks for the controllable assembly of useful, complex architectures.

Can the Σ-nn system be bound?

International Nuclear Information System (INIS)

Stadler, A.; Gibson, B.F.

1994-01-01

Motivated by the Σ-hypernuclear states reported in (K - ,π ± ) experiments, we have explored the possibility that there exists a particle-stable Σ - nn bound state. For the Juelich A hyperon-nucleon, realistic-force model, our calculations yield little reason to expect a positive-parity bound state or resonance in either the J=1/2 or the J=3/2 channels

Bounded Gaps between Products of Special Primes

Directory of Open Access Journals (Sweden)

Ping Ngai Chung

2014-03-01

Full Text Available In their breakthrough paper in 2006, Goldston, Graham, Pintz and Yıldırım proved several results about bounded gaps between products of two distinct primes. Frank Thorne expanded on this result, proving bounded gaps in the set of square-free numbers with r prime factors for any r ≥ 2, all of which are in a given set of primes. His results yield applications to the divisibility of class numbers and the triviality of ranks of elliptic curves. In this paper, we relax the condition on the number of prime factors and prove an analogous result using a modified approach. We then revisit Thorne’s applications and give a better bound in each case.

Yukawa Bound States and Their LHC Phenomenology

Directory of Open Access Journals (Sweden)

Enkhbat Tsedenbaljir

2013-01-01

Full Text Available We present the current status on the possible bound states of extra generation quarks. These include phenomenology and search strategy at the LHC. If chiral fourth-generation quarks do exist their strong Yukawa couplings, implied by current experimental lower bound on their masses, may lead to formation of bound states. Due to nearly degenerate 4G masses suggested by Precision Electroweak Test one can employ “heavy isospin” symmetry to classify possible spectrum. Among these states, the color-octet isosinglet vector ω 8 is the easiest to be produced at the LHC. The discovery potential and corresponding decay channels are covered in this paper. With possible light Higgs at ~125 GeV two-Higgs doublet version is briefly discussed.

Modeling nanoparticle uptake and intracellular distribution using stochastic process algebras

Energy Technology Data Exchange (ETDEWEB)

Dobay, M. P. D., E-mail: maria.pamela.david@physik.uni-muenchen.de; Alberola, A. Piera; Mendoza, E. R.; Raedler, J. O., E-mail: joachim.raedler@physik.uni-muenchen.de [Ludwig-Maximilians University, Faculty of Physics, Center for NanoScience (Germany)

2012-03-15

Computational modeling is increasingly important to help understand the interaction and movement of nanoparticles (NPs) within living cells, and to come to terms with the wealth of data that microscopy imaging yields. A quantitative description of the spatio-temporal distribution of NPs inside cells; however, it is challenging due to the complexity of multiple compartments such as endosomes and nuclei, which themselves are dynamic and can undergo fusion and fission and exchange their content. Here, we show that stochastic pi calculus, a widely-used process algebra, is well suited for mapping surface and intracellular NP interactions and distributions. In stochastic pi calculus, each NP is represented as a process, which can adopt various states such as bound or aggregated, as well as be passed between processes representing location, as a function of predefined stochastic channels. We created a pi calculus model of gold NP uptake and intracellular movement and compared the evolution of surface-bound, cytosolic, endosomal, and nuclear NP densities with electron microscopy data. We demonstrate that the computational approach can be extended to include specific molecular binding and potential interaction with signaling cascades as characteristic for NP-cell interactions in a wide range of applications such as nanotoxicity, viral infection, and drug delivery.

Modeling nanoparticle uptake and intracellular distribution using stochastic process algebras

International Nuclear Information System (INIS)

Dobay, M. P. D.; Alberola, A. Piera; Mendoza, E. R.; Rädler, J. O.

2012-01-01

Computational modeling is increasingly important to help understand the interaction and movement of nanoparticles (NPs) within living cells, and to come to terms with the wealth of data that microscopy imaging yields. A quantitative description of the spatio-temporal distribution of NPs inside cells; however, it is challenging due to the complexity of multiple compartments such as endosomes and nuclei, which themselves are dynamic and can undergo fusion and fission and exchange their content. Here, we show that stochastic pi calculus, a widely-used process algebra, is well suited for mapping surface and intracellular NP interactions and distributions. In stochastic pi calculus, each NP is represented as a process, which can adopt various states such as bound or aggregated, as well as be passed between processes representing location, as a function of predefined stochastic channels. We created a pi calculus model of gold NP uptake and intracellular movement and compared the evolution of surface-bound, cytosolic, endosomal, and nuclear NP densities with electron microscopy data. We demonstrate that the computational approach can be extended to include specific molecular binding and potential interaction with signaling cascades as characteristic for NP-cell interactions in a wide range of applications such as nanotoxicity, viral infection, and drug delivery.

Modeling nanoparticle uptake and intracellular distribution using stochastic process algebras

Science.gov (United States)

Dobay, M. P. D.; Alberola, A. Piera; Mendoza, E. R.; Rädler, J. O.

2012-03-01

Computational modeling is increasingly important to help understand the interaction and movement of nanoparticles (NPs) within living cells, and to come to terms with the wealth of data that microscopy imaging yields. A quantitative description of the spatio-temporal distribution of NPs inside cells; however, it is challenging due to the complexity of multiple compartments such as endosomes and nuclei, which themselves are dynamic and can undergo fusion and fission and exchange their content. Here, we show that stochastic pi calculus, a widely-used process algebra, is well suited for mapping surface and intracellular NP interactions and distributions. In stochastic pi calculus, each NP is represented as a process, which can adopt various states such as bound or aggregated, as well as be passed between processes representing location, as a function of predefined stochastic channels. We created a pi calculus model of gold NP uptake and intracellular movement and compared the evolution of surface-bound, cytosolic, endosomal, and nuclear NP densities with electron microscopy data. We demonstrate that the computational approach can be extended to include specific molecular binding and potential interaction with signaling cascades as characteristic for NP-cell interactions in a wide range of applications such as nanotoxicity, viral infection, and drug delivery.

Thermodynamic Upper Bound on Broadband Light Coupling with Photonic Structures

KAUST Repository

Yu, Zongfu; Raman, Aaswath; Fan, Shanhui

2012-01-01

to an upper bound dictated by the second law of thermodynamics. Such bound limits how efficient light can be coupled to any photonic structure. As one example of application, we use this upper bound to derive the limit of light absorption in broadband solar

Enhancement of radiation cytotoxicity by gold nanoparticles in MCF-7 breast cancer cell lines

Energy Technology Data Exchange (ETDEWEB)

Rosli, Nur Shafawati binti; Rahman, Azhar Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Aziz, Azlan Abdul [School of Physics, Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); Shamsuddin, Shaharum [Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800, Pulau Pinang (Malaysia); School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

2015-04-24

Therapy combined with metallic nanoparticles is a new way to treat cancer, in which gold nanoparticles (AuNPs) are injected through intravenous administration and bound to tumor sites. Radiotherapy aims to deliver a high therapeutic dose of ionizing radiation to the tumor without exceeding normal tissue tolerance. The use of AuNPs which is a high-atomic-number (Z) material in radiotherapy will provide a high probability for photon interaction by photoelectric effect. These provide advantages in terms of radiation dose enhancement. The high linear energy transfer and short range of photoelectric interaction products (photoelectrons, characteristic x-rays, Auger electrons) produce localized dose enhancement of the tumor. In this work, breast cancer cell lines (MCF-7) are seeded in the 96-well plate and were treated with 13 nm AuNPs before they were irradiated with 6 MV and 10 MV photon beam from a medical linear accelerator at various radiation doses. To validate the enhanced killing effect, both with and without AuNPs MCF-7 cells is irradiated simultaneously. By comparison, the results show that AuNPs significantly enhance cancer killing.

The question of an upper bound on entropy

International Nuclear Information System (INIS)

Qadir, A.

1982-08-01

We discuss the possibility, and significance, of an upper bound on entropy in the light of the arguments of Bekenstein and Unruh and Wald. We obtain a stricter bound than Bekenstein does, and point out some limitations with regard to its significance. (author)

Optimal Two Parameter Bounds for the Seiffert Mean

Directory of Open Access Journals (Sweden)

Hui Sun

2013-01-01

Full Text Available We obtain sharp bounds for the Seiffert mean in terms of a two parameter family of means. Our results generalize and extend the recent bounds presented in the Journal of Inequalities and Applications (2012 and Abstract and Applied Analysis (2012.

Rigorous bounds on the free energy of electron-phonon models

NARCIS (Netherlands)

Raedt, Hans De; Michielsen, Kristel

1997-01-01

We present a collection of rigorous upper and lower bounds to the free energy of electron-phonon models with linear electron-phonon interaction. These bounds are used to compare different variational approaches. It is shown rigorously that the ground states corresponding to the sharpest bounds do

Nanoparticle-nanoparticle interactions in biological media by Atomic Force Microscopy

Science.gov (United States)

Pyrgiotakis, Georgios; Blattmann, Christoph O.; Pratsinis, Sotiris; Demokritou, Philip

2015-01-01

Particle-particle interactions in physiological media are important determinants for nanoparticle fate and transport. Herein, such interactions are assessed by a novel Atomic Force Microscopy (AFM) based platform. Industry-relevant CeO2, Fe2O3, and SiO2 nanoparticles of various diameters were made by the flame spray pyrolysis (FSP) based Harvard Versatile Engineering Nanomaterials Generation System (Harvard VENGES). The nanoparticles were fully characterized structurally and morphologically and their properties in water and biological media were also assessed. The nanoparticles were attached on AFM tips and deposited on Si substrates to measure particle–particle interactions. The corresponding force was measured in air, water and biological media that are widely used in toxicological studies. The presented AFM based approach can be used to assess the agglomeration potential of nanoparticles in physiological fluids. The agglomeration potential of CeO2 nanoparticles in water and RPMI 1640 (Roswell Park Memorial Institute formulation 1640) was inversely proportional to their primary particle (PP) diameter, but for Fe2O3 nanoparticles, that potential is independent of PP diameter in these media. Moreover, in RPMI+10% Fetal Bovine Serum (FBS) the corona thickness and dispersibility of the CeO2 is independent of PP diameter while for Fe2O3, the corona thickness and dispersibility were inversely proportional to PP diameter. The present method can be combined with (dynamic light scattering (DLS), proteomics, and computer simulations to understand the nano-bio interactions, with emphasis on the agglomeration potential of nanoparticles and their transport in physiological media. PMID:23978039

Possible circumvention of Parker's bound on galactic magnetic monopoles

International Nuclear Information System (INIS)

Dicus, D.A.; Teplitz, V.L.

1983-04-01

There is a possibility that a magnetic monople has observed. The monopole density implied by the observation appears to violate bounds on the density of such particles derived from the total mass density of the universe and from the existence of galactic magnetic fields. We show that the observation is not inconsistent with these bounds if the monopoles and antimonopoles are bound into positronium - like states with principal quantum n high enough so that the earth's magnetic field will break them apart, but small enough so that the weaker galactic mangetic field will not. We determine a range of values for n and show that lifetimes for such bound states are longer than the current age of the universe

Fabrication and functionalization of magnesium nanoparticle for lipase immobilization in n-propyl gallate synthesis

Directory of Open Access Journals (Sweden)

Abhishek Sharma

2017-10-01

Full Text Available An extracellular lipase partially purified from Bacillus thermoamylovorans BHK67 was effectively immobilized onto modified magnetic MgFe2O4 nanoparticles (NPs. NPs were prepared by the sol-gel auto-combustion method and characterized by Fourier transform infrared (FTIR spectroscopy, X-ray diffraction (XRD, Ultra-Violet–Visible Spectroscopy (UV–vis and atomic force microscopy (AFM. Protein loading reached a saturated amount of about 0.20 mg lipase per milligram of MgFe2O4 NPs with 78.9% binding efficiency. The NPs-bound lipase also showed stability following exposure to n-propanol and iso-propanol or FeCl2 and MgCl2 metal ions at (1 mM at 55 °C. NPs-bound lipase also retained 50% of its original hydrolytic activity even after 8th cycle, as well as after 12 h of incubation at 55 °C. NPs-bound lipase in an esterification reaction of n-propanol and gallic acid (25 mM performed for 12 h at 55 °C produced n-propyl gallate with a conversion rate of 82%. Synthesized n-propyl gallate possessed strong antioxidant activity, which was confirmed by DPPH assay, and in addition has anticancerous activity which was tested on a human L132 cell line.

Bounds on the Effect of Progressive Structural Degradation

DEFF Research Database (Denmark)

Achtziger, W.; Bendsøe, Martin P; Taylor, John E.

1998-01-01

Problem formulations are presented for the evaluation of upper and lower bounds on the effect of progressive structural degradation. For the purposes of this study, degradation effect is measured by an increase in global structural compliance (flexibility). Thus the slated bounds are given simply...

Bounds for Tail Probabilities of the Sample Variance

Directory of Open Access Journals (Sweden)

Van Zuijlen M

2009-01-01

Full Text Available We provide bounds for tail probabilities of the sample variance. The bounds are expressed in terms of Hoeffding functions and are the sharpest known. They are designed having in mind applications in auditing as well as in processing data related to environment.

Bounds on the Effect of Progressive Structural Degradation

DEFF Research Database (Denmark)

Achtziger, Wolfgang; Bendsøe, Martin P; Taylor, John E.

1997-01-01

Problem formulations are presented for the evaluation of upper and lower bounds on the effect of progressive structural degradation. For the purposes of this study, degradation effect is measured by an increase in global structural compliance (flexibility). Thus the stated bounds are given simply...

Dynamic Garment Simulation based on Hybrid Bounding Volume Hierarchy

Directory of Open Access Journals (Sweden)

Zhu Dongyong

2016-12-01

Full Text Available In order to solve the computing speed and efficiency problem of existing dynamic clothing simulation, this paper presents a dynamic garment simulation based on a hybrid bounding volume hierarchy. It firstly uses MCASG graph theory to do the primary segmentation for a given three-dimensional human body model. And then it applies K-means cluster to do the secondary segmentation to collect the human body’s upper arms, lower arms, upper legs, lower legs, trunk, hip and woman’s chest as the elementary units of dynamic clothing simulation. According to different shapes of these elementary units, it chooses the closest and most efficient hybrid bounding box to specify these units, such as cylinder bounding box and elliptic cylinder bounding box. During the process of constructing these bounding boxes, it uses the least squares method and slices of the human body to get the related parameters. This approach makes it possible to use the least amount of bounding boxes to create close collision detection regions for the appearance of the human body. A spring-mass model based on a triangular mesh of the clothing model is finally constructed for dynamic simulation. The simulation result shows the feasibility and superiority of the method described.

Viscosity bound violation in holographic solids and the viscoelastic response

Energy Technology Data Exchange (ETDEWEB)

Alberte, Lasma [Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, 34151, Trieste (Italy); Baggioli, Matteo [Institut de Física d’Altes Energies (IFAE),The Barcelona Institute of Science and Technology (BIST),Campus UAB, 08193 Bellaterra, Barcelona (Spain); Department of Physics, Institute for Condensed Matter Theory, University of Illinois,1110 W. Green Street, Urbana, IL 61801 (United States); Pujolàs, Oriol [Institut de Física d’Altes Energies (IFAE),The Barcelona Institute of Science and Technology (BIST),Campus UAB, 08193 Bellaterra, Barcelona (Spain)

2016-07-14

We argue that the Kovtun-Son-Starinets (KSS) lower bound on the viscosity to entropy density ratio holds in fluid systems but is violated in solid materials with a non-zero shear elastic modulus. We construct explicit examples of this by applying the standard gauge/gravity duality methods to massive gravity and show that the KSS bound is clearly violated in black brane solutions whenever the massive gravity theories are of solid type. We argue that the physical reason for the bound violation relies on the viscoelastic nature of the mechanical response in these materials. We speculate on whether any real-world materials can violate the bound and discuss a possible generalization of the bound that involves the ratio of the shear elastic modulus to the pressure.

Viscosity bound violation in holographic solids and the viscoelastic response

International Nuclear Information System (INIS)

Alberte, Lasma; Baggioli, Matteo; Pujolàs, Oriol

2016-01-01

We argue that the Kovtun-Son-Starinets (KSS) lower bound on the viscosity to entropy density ratio holds in fluid systems but is violated in solid materials with a non-zero shear elastic modulus. We construct explicit examples of this by applying the standard gauge/gravity duality methods to massive gravity and show that the KSS bound is clearly violated in black brane solutions whenever the massive gravity theories are of solid type. We argue that the physical reason for the bound violation relies on the viscoelastic nature of the mechanical response in these materials. We speculate on whether any real-world materials can violate the bound and discuss a possible generalization of the bound that involves the ratio of the shear elastic modulus to the pressure.

Bound states in curved quantum waveguides

International Nuclear Information System (INIS)

Exner, P.; Seba, P.

1987-01-01

We study free quantum particle living on a curved planar strip Ω of a fixed width d with Dirichlet boundary conditions. It can serve as a model for electrons in thin films on a cylindrical-type substrate, or in a curved quantum wire. Assuming that the boundary of Ω is infinitely smooth and its curvature decays fast enough at infinity, we prove that a bound state with energy below the first transversal mode exists for all sufficiently small d. A lower bound on the critical width is obtained using the Birman-Schwinger technique. (orig.)

Bound constrained quadratic programming via piecewise

DEFF Research Database (Denmark)

Madsen, Kaj; Nielsen, Hans Bruun; Pinar, M. C.

1999-01-01

of a symmetric, positive definite matrix, and is solved by Newton iteration with line search. The paper describes the algorithm and its implementation including estimation of lambda/sub 1/ , how to get a good starting point for the iteration, and up- and downdating of Cholesky factorization. Results of extensive......We consider the strictly convex quadratic programming problem with bounded variables. A dual problem is derived using Lagrange duality. The dual problem is the minimization of an unconstrained, piecewise quadratic function. It involves a lower bound of lambda/sub 1/ , the smallest eigenvalue...

Synthesis and characterization of vanadium doped SnO2 diluted magnetic semiconductor nanoparticles with enhanced photocatalytic activities

International Nuclear Information System (INIS)

Mazloom, J.; Ghodsi, F.E.; Golmojdeh, H.

2015-01-01

Highlights: • Pure and V-doped SnO 2 nanoparticles were synthesized using a facile sol–gel route. • The V 4+ ions were incorporated into the SnO 2 lattice and located at the Sn 4+ sites. • TEM images reveled that by increasing the doping content, average grain size decreased. • We show that the V-doped SnO 2 is more photoactive than undoped SnO 2 . • The V-doped SnO 2 nanoparticles exhibited ferromagnetism at room temperature. - Abstract: Vanadium doped SnO 2 nanoparticles were synthesized by a facile sol–gel method. Different analytical techniques including TG/DTG, XRD, XPS, VSM and PL were used to investigate the influence of dopant concentration on structural, morphological, compositional, magnetic and optical properties of prepared nanoparticles. The XRD study showed a dominant tetragonal structure. The X-ray photoelectron spectroscopy proved the presence of vanadium as V 4+ species. TEM image revealed that particle size decrease by doping. It was found that room temperature ferromagnetic (RTFM) behavior is strongly dependent on vanadium dopant content and the magnetic saturation dropped rapidly with increasing V content, which can be explained reasonably through bound magnetic polaron (BMP) model. A quenching in green luminescence intensity was observed in V-doped SnO 2 compared to undoped sample. The 5% V-doped SnO 2 sample showed better photocatalytic activity than undoped one in decomposing methylene blue and rhodamine B

Dynamics of bleomycin interaction with a strongly bound hairpin DNA substrate, and implications for cleavage of the bound DNA.

Science.gov (United States)

Bozeman, Trevor C; Nanjunda, Rupesh; Tang, Chenhong; Liu, Yang; Segerman, Zachary J; Zaleski, Paul A; Wilson, W David; Hecht, Sidney M

2012-10-31

Recent studies involving DNAs bound strongly by bleomycins have documented that such DNAs are degraded by the antitumor antibiotic with characteristics different from those observed when studying the cleavage of randomly chosen DNAs in the presence of excess Fe·BLM. In the present study, surface plasmon resonance has been used to characterize the dynamics of BLM B(2) binding to a strongly bound hairpin DNA, to define the effects of Fe(3+), salt, and temperature on BLM-DNA interaction. One strong primary DNA binding site, and at least one much weaker site, were documented. In contrast, more than one strong cleavage site was found, an observation also made for two other hairpin DNAs. Evidence is presented for BLM equilibration between the stronger and weaker binding sites in a way that renders BLM unavailable to other, less strongly bound DNAs. Thus, enhanced binding to a given site does not necessarily result in increased DNA degradation at that site; i.e., for strongly bound DNAs, the facility of DNA cleavage must involve other parameters in addition to the intrinsic rate of C-4' H atom abstraction from DNA sugars.

GISAXS analysis of 3D nanoparticle assemblies—effect of vertical nanoparticle ordering

International Nuclear Information System (INIS)

Vegso, K; Siffalovic, P; Benkovicova, M; Jergel, M; Luby, S; Majkova, E; Capek, I; Kocsis, T; Perlich, J; Roth, S V

2012-01-01

We report on grazing-incidence small-angle x-ray scattering (GISAXS) study of 3D nanoparticle arrays prepared by two different methods from colloidal solutions—layer-by-layer Langmuir–Schaefer deposition and spontaneous self-assembling during the solvent evaporation. GISAXS results are evaluated within the distorted wave Born approximation (DWBA) considering the multiple scattering effects and employing a simplified multilayer model to reduce the computing time. In the model, particular layers are represented by nanoparticle chains where the positions of individual nanoparticles are generated following a model of cumulative disorder. The nanoparticle size dispersion is considered as well. Three model cases are distinguished—no shift between the neighboring chains (AA stacking), a shift equal to half of the mean interparticle distance (AB stacking) and random shift between the chains. The first two cases correspond to vertically correlated nanoparticle positions across different chains. A comparison of the experimental GISAXS patterns with the model cases enabled us to distinguish important differences between the 3D arrays prepared by the two methods. In particular, laterally ordered layers without vertical correlation of the nanoparticle positions were found in the nanoparticle multilayers prepared by the Langmuir–Schaefer method. On the other hand, the solvent evaporation under particular conditions produced highly ordered 3D nanoparticle assemblies where both laterally and vertically correlated nanoparticle positions were found. (paper)

Chemical coupling of carbon nanotubes and silicon nanoparticles for improved negative electrode performance in lithium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Martin, Cedric; Crosnier, Olivier; Schleich, Donald M.; Brousse, Thierry [Laboratoire de Genie des Materiaux et Procedes Associes (LGMPA), Ecole Polytechnique de l' Universite de Nantes, Rue Christian Pauc, BP50609, 44306 Nantes Cedex 3 (France); Retoux, Richard [Laboratoire CRISMAT-CNRS/UMR 6508, ENSICAEN, Universite de Caen Basse-Normandie, 6 bd Marechal Juin, 14050 Caen (France); Belanger, Daniel [Departement de Chimie, Universite du Quebec a Montreal, succursale Centre-Ville, Montreal, Quebec, H3C 3P8 (Canada)

2011-09-23

Multi-walled carbon nanotube (MWCNT)/silicon nanocomposites obtained by a grafting technique using the diazonium chemistry are used to prepare silicon negative electrodes for lithium-ion batteries. The covalent bonding of the two compounds is obtained via mono- and multi-layers of phenyl bridges, leading to an ideal dispersion of MWCNTs and silicon nanoparticles that are bound together. The presence of MWCNTs close to silicon nanoparticles enhances the electronic pathway to the active material particles and probably helps to prevent silicon decrepitation upon repeated lithium insertion/extraction by improving the mechanical stability of the electrode at a nanoscale level. This effect results in the enhancement of cycling ability and capacity, which are demonstrated by comparing the nanocomposite electrode to a simple mixture of the two compounds. This technique can be applied to other carbon conductive additives together with silicon or other nanosized active compounds. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Hydrothermal synthesis of hydroxyapatite nanoparticles decorated with silver nanoparticles for application in biomaterials

International Nuclear Information System (INIS)

Assis, Jordanna Fernandes; Arantes, Tatiane Moraes; Cristovan, F.H.; Tada, Dayane Batista

2016-01-01

Full text: The hydroxyapatite nanoparticles (HA) have research attention because are material that exhibit biocompatibility with bone mineral phase of human body is great interest in the scientific community. Synthetic hydroxyapatite nanoparticles have excellent biocompatibility and bioactivity, due biocompatibility and osteo inducibility [1-3]. The hydroxyapatite nanoparticles were synthesized by hydrothermal processing and were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The XRD and Raman spectra showed crystalline hydroxyapatite colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated hydroxyapatite surface. TEM images showed HA nanoparticles presented a well defined nanorod shapes and narrow size distributions with dimensions (width and length) around of 5 nm and 50 nm decorated with silver nanoparticles of spherical shape about 20 nm in diameter The results showed that crystalline hydroxyapatite colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. These nanoparticles The cell viability of the HA and HA/Ag was analyzed by reduction of the tetrazolium salt (MTT test). Embryonic mouse fibroblast cells were grown in the presence of nanoparticles for a total period of 96 hours. Analyses were made in 24h, 48h, 72h and 96h. The suspensions at the end of each period were analyzed in spectrophotometer. The 24h experiments were the most conclusive, with the silver presence in the HA, there is an increased in cellular proliferation. The results demonstrated that the HA/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

Hydrothermal synthesis of hydroxyapatite nanoparticles decorated with silver nanoparticles for application in biomaterials

Energy Technology Data Exchange (ETDEWEB)

Assis, Jordanna Fernandes; Arantes, Tatiane Moraes, E-mail: fernandes.jordanna9@gmail.com [Universidade Federal de Goias (UFG), Goiania (Brazil); Cristovan, F.H.; Tada, Dayane Batista [Universidade Federal de Sao Paulo (UNIFESP), Sao Jose dos Campos, SP (Brazil)

2016-07-01

Full text: The hydroxyapatite nanoparticles (HA) have research attention because are material that exhibit biocompatibility with bone mineral phase of human body is great interest in the scientific community. Synthetic hydroxyapatite nanoparticles have excellent biocompatibility and bioactivity, due biocompatibility and osteo inducibility [1-3]. The hydroxyapatite nanoparticles were synthesized by hydrothermal processing and were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The XRD and Raman spectra showed crystalline hydroxyapatite colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated hydroxyapatite surface. TEM images showed HA nanoparticles presented a well defined nanorod shapes and narrow size distributions with dimensions (width and length) around of 5 nm and 50 nm decorated with silver nanoparticles of spherical shape about 20 nm in diameter The results showed that crystalline hydroxyapatite colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. These nanoparticles The cell viability of the HA and HA/Ag was analyzed by reduction of the tetrazolium salt (MTT test). Embryonic mouse fibroblast cells were grown in the presence of nanoparticles for a total period of 96 hours. Analyses were made in 24h, 48h, 72h and 96h. The suspensions at the end of each period were analyzed in spectrophotometer. The 24h experiments were the most conclusive, with the silver presence in the HA, there is an increased in cellular proliferation. The results demonstrated that the HA/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

Upper and lower bounds in nonrelativistic scattering theory

International Nuclear Information System (INIS)

Darewych, J.W.; Pooran, R.

1980-01-01

We consider the problem of determining rigorous upper and lower bounds to the difference between the exact and approximate scattering phase shift, for the case of central potential scattering. The present work is based on the Kato identities and the phase-amplitude formalism of potential scattering developed by Calogero. For nonstationary approximations, a new first-order (in small quantities) bound is established which is particularly useful for partial waves other than s waves. Similar, but second-order, bounds are established for approximations which are stationary. Some previous results, based on the use of the Lippman--Schwinger equation are generalized, and some new bounds are established. These are illustrated, and compared to previous results, by a simple example. We discuss the advantages and disadvantages of the present results in comparison to those derived previously. Finally, we present the generalization of some of the present formalism to the case of many-channel scattering involving many-particle systems, and discuss some of the difficulties of their practical implementation

HiggsBounds-4. Improved tests of extended Higgs sectors against exclusion bounds from LEP, the Tevatron and the LHC

Energy Technology Data Exchange (ETDEWEB)

Bechtle, Philip [Bonn Univ. (Germany). Physikalisches Inst.; Heinemeyer, Sven [Instituto de Fisica de Cantabria (CSIC-UC), Santander (Spain); Staal, Oscar [Stockholm Univ. (Sweden). Dept. of Physics; Stefaniak, Tim; Williams, Karina E. [Bonn Univ. (Germany). Physikalisches Inst.; Bonn Univ. (Germany). Bethe Center for Theoretical Physics; Weiglein, Georg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Brein, Oliver

2013-12-15

We describe the new developments in version 4 of the public computer code HiggsBounds. HiggsBounds is a tool to test models with arbitrary Higgs sectors, containing both neutral and charged Higgs bosons, against the published exclusion bounds from Higgs searches at the LEP, Tevatron and LHC experiments. From the model predictions for the Higgs masses, branching ratios, production cross sections and total decay widths - which are specified by the user in the input for the program - the code calculates the predicted signal rates for the search channels considered in the experimental data. The signal rates are compared to the expected and observed cross section limits from the Higgs searches to determine whether a point in the model parameter space is excluded at 95% confidence level. In this paper we present a modification of the HiggsBounds main algorithm that extends the exclusion test in order to ensure that it provides useful results in the presence of one or more significant excesses in the data, corresponding to potential Higgs signals. We also describe a new method to test whether the limits from an experimental search performed under certain model assumptions can be applied to a different theoretical model. Further developments discussed here include a framework to take into account theoretical uncertainties on the Higgs mass predictions, and the possibility to obtain the {chi}{sup 2} likelihood of Higgs exclusion limits from LEP. Extensions to the user subroutines from earlier versions of HiggsBounds are described. The new features are demonstrated by additional example programs.

HiggsBounds-4. Improved tests of extended Higgs sectors against exclusion bounds from LEP, the Tevatron and the LHC

International Nuclear Information System (INIS)

Bechtle, Philip; Staal, Oscar; Brein, Oliver

2013-12-01

We describe the new developments in version 4 of the public computer code HiggsBounds. HiggsBounds is a tool to test models with arbitrary Higgs sectors, containing both neutral and charged Higgs bosons, against the published exclusion bounds from Higgs searches at the LEP, Tevatron and LHC experiments. From the model predictions for the Higgs masses, branching ratios, production cross sections and total decay widths - which are specified by the user in the input for the program - the code calculates the predicted signal rates for the search channels considered in the experimental data. The signal rates are compared to the expected and observed cross section limits from the Higgs searches to determine whether a point in the model parameter space is excluded at 95% confidence level. In this paper we present a modification of the HiggsBounds main algorithm that extends the exclusion test in order to ensure that it provides useful results in the presence of one or more significant excesses in the data, corresponding to potential Higgs signals. We also describe a new method to test whether the limits from an experimental search performed under certain model assumptions can be applied to a different theoretical model. Further developments discussed here include a framework to take into account theoretical uncertainties on the Higgs mass predictions, and the possibility to obtain the χ 2 likelihood of Higgs exclusion limits from LEP. Extensions to the user subroutines from earlier versions of HiggsBounds are described. The new features are demonstrated by additional example programs.

Upper bound on the capacity of constrained three-dimensional codes

DEFF Research Database (Denmark)

Forchhammer, Søren

2000-01-01

An upper bound on the capacity of constrained three-dimensional codes is presented. The bound for two-dimensional codes of Calkin and Wilf (see SIAM Journal of Discrete Mathematics, vol.11, no.1, p.54-60, 1998) was extended to three dimensions by Nagy and Zeger. Both bounds apply to first order s...

Relevance of the ICRP biokinetic model for dietary organically bound tritium

International Nuclear Information System (INIS)

Trivedi, A.

1999-10-01

Ingested dietary tritium can participate in metabolic processes, and become synthesized into organically bound tritium in the tissues and organs. The distribution and retention of the organically bound tritium throughout the body are much different than tritium in the body water. The International Commission on Radiological Protection (ICRP) Publication 56 (1989) has a biokinetic model to calculate dose from the ingestion of organically bound dietary tritium. The model predicts that the dose from the ingestion of organically bound dietary tritium is about 2.3 times higher than from the ingestion of the same activity of tritiated water. Under steady-state conditions, the calculated dose rate (using the first principle approach) from the ingestion of dietary organically bound tritium can be twice that from the ingestion of tritiated water. For an adult, the upper-bound dose estimate for the ingestion of dietary organically bound tritium is estimated to be close to 2.3 times higher than that of tritiated water. Therefore, given the uncertainty in the dose calculation with respect to the actual relevant dose, the ICRP biokinetic model for organically bound tritium is sufficient for dosimetry for adults. (author)

Dielectric structures with bound modes for microcavity lasers

NARCIS (Netherlands)

Visser, P.M.; Allaart, K.; Lenstra, D.

2002-01-01

Cavity modes of dielectric microsphcres and vertical cavity surface emitting lasers, in spite of their high Q, are never exactly bound, but have a finite width due to leakage at the borders. We propose types of microstructures that sustain three-dimensionally bound modes of the radiation field when

Towards an abstract parallel branch and bound machine

NARCIS (Netherlands)

A. de Bruin (Arie); G.A.P. Kindervater (Gerard); H.W.J.M. Trienekens

1995-01-01

textabstractMany (parallel) branch and bound algorithms look very different from each other at first glance. They exploit, however, the same underlying computational model. This phenomenon can be used to define branch and bound algorithms in terms of a set of basic rules that are applied in a

Bound state and localization of excitation in many-body open systems

Science.gov (United States)

Cui, H. T.; Shen, H. Z.; Hou, S. C.; Yi, X. X.

2018-04-01

We study the exact bound state and time evolution for single excitations in one-dimensional X X Z spin chains within a non-Markovian reservoir. For the bound state, a common feature is the localization of single excitations, which means the spontaneous emission of excitations into the reservoir is prohibited. Exceptionally, the pseudo-bound state can be found, for which the single excitation has a finite probability of emission into the reservoir. In addition, a critical energy scale for bound states is also identified, below which only one bound state exists, and it is also the pseudo-bound state. The effect of quasirandom disorder in the spin chain is also discussed; such disorder induces the single excitation to locate at some spin sites. Furthermore, to display the effect of bound state and disorder on the preservation of quantum information, the time evolution of single excitations in spin chains is studied exactly. An interesting observation is that the excitation can stay at its initial location with high probability only when the bound state and disorder coexist. In contrast, when either one of them is absent, the information of the initial state can be erased completely or becomes mixed. This finding shows that the combination of bound state and disorder can provide an ideal mechanism for quantum memory.

Bounded Rationality in Transposition Processes

DEFF Research Database (Denmark)

Vollaard, Hans; Martinsen, Dorte Sindbjerg

2014-01-01

Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first that con......Studies explaining the timeliness and correctness of the transposition of EU directives into national legislation have provided rather inconclusive findings. They do not offer a clear-cut prediction concerning the transposition of the patients’ rights directive, which is one of the first...... that concerns the organisation and financing of national healthcare systems. This article applies the perspective of bounded rationality to explain (irregularities in) the timely and correct transposition of EU directives. The cognitive and organisational constraints long posited by the bounded rationality...

Mannan-Modified PLGA Nanoparticles for Targeted Gene Delivery

Directory of Open Access Journals (Sweden)

Fansheng Kong

2012-01-01

Full Text Available The studies of targeted gene delivery nanocarriers have gained increasing attention during the past decades. In this study, mannan modified DNA loaded bioadhesive PLGA nanoparticles (MAN-DNA-NPs were investigated for targeted gene delivery to the Kupffer cells (KCs. Bioadhesive PLGA nanoparticles were prepared and subsequently bound with pEGFP. Following the coupling of the mannan-based PE-grafted ligands (MAN-PE with the DNA-NPs, the MAN-DNA-NPs were delivered intravenously to rats. The transfection efficiency was determined from the isolated KCs and flow cytometry was applied for the quantitation of gene expression after 48 h post transfection. The size of the MAN-DNA-NPs was found to be around 190 nm and the Zeta potential was determined to be −15.46mV. The pEGFP binding capacity of MAN-DNA-NPs was (88.9±5.8% and the in vitro release profiles of the MAN-DNA-NPs follow the Higuchi model. When compared with non-modified DNA-NPs and Lipofectamine 2000-DNA, MAN-DNA-NPs produced the highest gene expressions, especially in vivo. The in vivo data from flow cytometry analysis showed that MAN-DNA-NPs displayed a remarkably higher transfection efficiency (39% than non-modified DNA-NPs (25% and Lipofectamine 2000-DNA (23% in KCs. The results illustrate that MAN-DNA-NPs have the ability to target liver KCs and could function as promising active targeting drug delivery vectors.

Humid Heat Autoclaving of Hybrid Nanoparticles Achieved by Decreased Nanoparticle Concentration and Improved Nanoparticle Stability Using Medium Chain Triglycerides as a Modifier.

Science.gov (United States)

Gou, Jingxin; Chao, Yanhui; Liang, Yuheng; Zhang, Ning; He, Haibing; Yin, Tian; Zhang, Yu; Xu, Hui; Tang, Xing

2016-09-01

Humid heat autoclaving is a facile technique widely used in the sterilization of injections, but the high temperature employed would destroy nanoparticles composed of biodegradable polymers. The aim of this study was to investigate whether incorporation of medium chain triglycerides (MCT) could stabilize nanoparticles composed of poly (ethylene glycol)-b-polycaprolactone (PEG-b-PCL) during autoclaving (121°C, 10 min). Polymeric nanoparticles with different MCT contents were prepared by dialysis. Block copolymer degradation was studied by GPC. The critical aggregation concentrations of nanoparticles at different temperatures were determined using pyrene fluorescence. The size, morphology and weight averaged molecular weight of pristine/autoclaved nanoparticles were studied using DLS, TEM and SLS, respectively. Drug loading content and release profile were determined using RP-HPLC. The protecting effect of MCT on nanoparticles was dependent on the amount of MCT incorporated. Nanoparticles with high MCT contents, which assumed an emulsion-like morphology, showed reduced block copolymer degradation and particle disassociation after incubation at 100°C for 24 h. Nanoparticles with high MCT content showed the lowest critical aggregation concentration (CAC) under either room temperature or 60°C and the lowest particle concentration among all samples. And the particle size, drug loading content, physical stability and release profile of nanoparticles with high MCT contents remained nearly unchanged after autoclaving. Incorporation of high amount of MCT changed the morphology of PEG-b-PCL based nanoparticles to an emulsion-like structure and the nanoparticles prepared could withstand autoclaving due to improved particle stability and decreased particle concentration caused by MCT incorporation.

Progress toward clonable inorganic nanoparticles

Science.gov (United States)

Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi L.; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth A. H.; Ackerson, Christopher J.

2015-10-01

Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular

Bound on viscosity and the generalized second law of thermodynamics

International Nuclear Information System (INIS)

Fouxon, Itzhak; Betschart, Gerold; Bekenstein, Jacob D.

2008-01-01

We describe a new paradox for ideal fluids. It arises in the accretion of an ideal fluid onto a black hole, where, under suitable boundary conditions, the flow can violate the generalized second law of thermodynamics. The paradox indicates that there is in fact a lower bound to the correlation length of any real fluid, the value of which is determined by the thermodynamic properties of that fluid. We observe that the universal bound on entropy, itself suggested by the generalized second law, puts a lower bound on the correlation length of any fluid in terms of its specific entropy. With the help of a new, efficient estimate for the viscosity of liquids, we argue that this also means that viscosity is bounded from below in a way reminiscent of the conjectured Kovtun-Son-Starinets lower bound on the ratio of viscosity to entropy density. We conclude that much light may be shed on the Kovtun-Son-Starinets bound by suitable arguments based on the generalized second law

Silver nanoparticle-enriched diamond-like carbon implant modification as a mammalian cell compatible surface with antimicrobial properties

Science.gov (United States)

Gorzelanny, Christian; Kmeth, Ralf; Obermeier, Andreas; Bauer, Alexander T.; Halter, Natalia; Kümpel, Katharina; Schneider, Matthias F.; Wixforth, Achim; Gollwitzer, Hans; Burgkart, Rainer; Stritzker, Bernd; Schneider, Stefan W.

2016-01-01

The implant-bone interface is the scene of competition between microorganisms and distinct types of tissue cells. In the past, various strategies have been followed to support bony integration and to prevent bacterial implant-associated infections. In the present study we investigated the biological properties of diamond-like carbon (DLC) surfaces containing silver nanoparticles. DLC is a promising material for the modification of medical implants providing high mechanical and chemical stability and a high degree of biocompatibility. DLC surface modifications with varying silver concentrations were generated on medical-grade titanium discs, using plasma immersion ion implantation-induced densification of silver nanoparticle-containing polyvinylpyrrolidone polymer solutions. Immersion of implants in aqueous liquids resulted in a rapid silver release reducing the growth of surface-bound and planktonic Staphylococcus aureus and Staphylococcus epidermidis. Due to the fast and transient release of silver ions from the modified implants, the surfaces became biocompatible, ensuring growth of mammalian cells. Human endothelial cells retained their cellular differentiation as indicated by the intracellular formation of Weibel-Palade bodies and a high responsiveness towards histamine. Our findings indicate that the integration of silver nanoparticles into DLC prevents bacterial colonization due to a fast initial release of silver ions, facilitating the growth of silver susceptible mammalian cells subsequently. PMID:26955791

On the nature of citrate-derived surface species on Ag nanoparticles: Insights from X-ray photoelectron spectroscopy

Science.gov (United States)

Mikhlin, Yuri L.; Vorobyev, Sergey A.; Saikova, Svetlana V.; Vishnyakova, Elena A.; Romanchenko, Alexander S.; Zharkov, Sergey M.; Larichev, Yurii V.

2018-01-01

Citrate is an important stabilizing, reducing, and complexing reagent in the wet chemical synthesis of nanoparticles of silver and other metals, however, the exact nature of adsorbates, and its mechanism of action are still uncertain. Here, we applied X-ray photoelectron spectroscopy, soft X-ray absorption near-edge spectroscopy, and other techniques in order to determine the surface composition and to specify the citrate-related species at Ag nanoparticles immobilized from the dense hydrosol prepared using room-temperature reduction of aqueous Ag+ ions with ferrous ions and citrate as stabilizer (Carey Lea method). It was found that, contrary to the common view, the species adsorbed on the Ag nanoparticles are, in large part, products of citrate decomposition comprising an alcohol group and one or two carboxylate bound to the surface Ag, and minor unbound carboxylate group; these may also be mixtures of citrate with lower molecular weight anions. No ketone groups were specified, and very minor surface Ag(I) and Fe (mainly, ferric oxyhydroxides) species were detected. Moreover, the adsorbates were different at AgNPs having various size and shape. The relation between the capping and the particle growth, colloidal stability of the high-concentration sol and properties of AgNPs is briefly considered.

Lower Bounds in the Asymmetric External Memory Model

DEFF Research Database (Denmark)

Jacob, Riko; Sitchinava, Nodari

2017-01-01

Motivated by the asymmetric read and write costs of emerging non-volatile memory technologies, we study lower bounds for the problems of sorting, permuting and multiplying a sparse matrix by a dense vector in the asymmetric external memory model (AEM). Given an AEM with internal (symmetric) memory...... of size M, transfers between symmetric and asymmetric memory in blocks of size B and the ratio ω between write and read costs, we show Ω(min (N, ωN/B logω M/B N/B) lower bound for the cost of permuting N input elements. This lower bound also applies to the problem of sorting N elements. This proves...

Adsorption energies of poly(ethylene oxide)-based surfactants and nanoparticles on an air-water surface.

Science.gov (United States)

Zell, Zachary A; Isa, Lucio; Ilg, Patrick; Leal, L Gary; Squires, Todd M

2014-01-14

The self-assembly of polymer-based surfactants and nanoparticles on fluid-fluid interfaces is central to many applications, including dispersion stabilization, creation of novel 2D materials, and surface patterning. Very often these processes involve compressing interfacial monolayers of particles or polymers to obtain a desired material microstructure. At high surface pressures, however, even highly interfacially active objects can desorb from the interface. Methods of directly measuring the energy which keeps the polymer or particles bound to the interface (adsorption/desorption energies) are therefore of high interest for these processes. Moreover, though a geometric description linking adsorption energy and wetting properties through the definition of a contact angle can be established for rigid nano- or microparticles, such a description breaks down for deformable or aggregating objects. Here, we demonstrate a technique to quantify desorption energies directly, by comparing surface pressure-density compression measurements using a Wilhelmy plate and a custom-microfabricated deflection tensiometer. We focus on poly(ethylene oxide)-based polymers and nanoparticles. For PEO-based homo- and copolymers, the adsorption energy of PEO chains scales linearly with molecular weight and can be tuned by changing the subphase composition. Moreover, the desorption surface pressure of PEO-stabilized nanoparticles corresponds to the saturation surface pressure for spontaneously adsorbed monolayers, yielding trapping energies of ∼10(3) k(B)T.

Volume dependence of N-body bound states

Science.gov (United States)

König, Sebastian; Lee, Dean

2018-04-01

We derive the finite-volume correction to the binding energy of an N-particle quantum bound state in a cubic periodic volume. Our results are applicable to bound states with arbitrary composition and total angular momentum, and in any number of spatial dimensions. The only assumptions are that the interactions have finite range. The finite-volume correction is a sum of contributions from all possible breakup channels. In the case where the separation is into two bound clusters, our result gives the leading volume dependence up to exponentially small corrections. If the separation is into three or more clusters, there is a power-law factor that is beyond the scope of this work, however our result again determines the leading exponential dependence. We also present two independent methods that use finite-volume data to determine asymptotic normalization coefficients. The coefficients are useful to determine low-energy capture reactions into weakly bound states relevant for nuclear astrophysics. Using the techniques introduced here, one can even extract the infinite-volume energy limit using data from a single-volume calculation. The derived relations are tested using several exactly solvable systems and numerical examples. We anticipate immediate applications to lattice calculations of hadronic, nuclear, and cold atomic systems.

Scattering theory methods for bound state problems

International Nuclear Information System (INIS)

Raphael, R.B.; Tobocman, W.

1978-01-01

For the analysis of the properties of a bound state system one may use in place of the Schroedinger equation the Lippmann-Schwinger (LS) equation for the wave function or the LS equation for the reactance operator. Use of the LS equation for the reactance operator constrains the solution to have correct asymptotic behaviour, so this approach would appear to be desirable when the bound state wave function is to be used to calculate particle transfer form factors. The Schroedinger equation based N-level analysis of the s-wave bound states of a square well is compared to the ones based on the LS equation. It is found that the LS equation methods work better than the Schroedinger equation method. The method that uses the LS equation for the wave function gives the best results for the wave functions while the method that uses the LS equation for the reactance operator gives the best results for the binding energies. The accuracy of the reactance operator based method is remarkably insensitive to changes in the oscillator constant used for the harmonic oscillator function basis set. It is also remarkably insensitive to the number of nodes in the bound state wave function. (Auth.)

Efficiency bounds for nonequilibrium heat engines

International Nuclear Information System (INIS)

Mehta, Pankaj; Polkovnikov, Anatoli

2013-01-01

We analyze the efficiency of thermal engines (either quantum or classical) working with a single heat reservoir like an atmosphere. The engine first gets an energy intake, which can be done in an arbitrary nonequilibrium way e.g. combustion of fuel. Then the engine performs the work and returns to the initial state. We distinguish two general classes of engines where the working body first equilibrates within itself and then performs the work (ergodic engine) or when it performs the work before equilibrating (non-ergodic engine). We show that in both cases the second law of thermodynamics limits their efficiency. For ergodic engines we find a rigorous upper bound for the efficiency, which is strictly smaller than the equivalent Carnot efficiency. I.e. the Carnot efficiency can be never achieved in single reservoir heat engines. For non-ergodic engines the efficiency can be higher and can exceed the equilibrium Carnot bound. By extending the fundamental thermodynamic relation to nonequilibrium processes, we find a rigorous thermodynamic bound for the efficiency of both ergodic and non-ergodic engines and show that it is given by the relative entropy of the nonequilibrium and initial equilibrium distributions. These results suggest a new general strategy for designing more efficient engines. We illustrate our ideas by using simple examples. -- Highlights: ► Derived efficiency bounds for heat engines working with a single reservoir. ► Analyzed both ergodic and non-ergodic engines. ► Showed that non-ergodic engines can be more efficient. ► Extended fundamental thermodynamic relation to arbitrary nonequilibrium processes

Computing variational bounds for flow through random aggregates of Spheres

International Nuclear Information System (INIS)

Berryman, J.G.

1983-01-01

Known formulas for variational bounds on Darcy's constant for slow flow through porous media depend on two-point and three-poiint spatial correlation functions. Certain bounds due to Prager and Doi depending only a two-point correlation functions have been calculated for the first time for random aggregates of spheres with packing fractions (eta) up to eta = 0.64. Three radial distribution functions for hard spheres were tested for eta up to 0.49: (1) the uniform distribution or ''well-stirred approximation,'' (2) the Percus Yevick approximation, and (3) the semi-empirical distribution of Verlet and Weis. The empirical radial distribution functions of Benett andd Finney were used for packing fractions near the random-close-packing limit (eta/sub RCP/dapprox.0.64). An accurate multidimensional Monte Carlo integration method (VEGAS) developed by Lepage was used to compute the required two-point correlation functions. The results show that Doi's bounds are preferred for eta>0.10 while Prager's bounds are preferred for eta>0.10. The ''upper bounds'' computed using the well-stirred approximation actually become negative (which is physically impossible) as eta increases, indicating the very limited value of this approximation. The other two choices of radial distribution function give reasonable results for eta up to 0.49. However, these bounds do not decrease with eta as fast as expected for large eta. It is concluded that variational bounds dependent on three-point correlation functions are required to obtain more accurate bounds on Darcy's constant for large eta

Bounding the space of holographic CFTs with chaos

Energy Technology Data Exchange (ETDEWEB)

Perlmutter, Eric [Department of Physics, Princeton University,Jadwin Hall, Princeton, NJ 08544 (United States)

2016-10-13

Thermal states of quantum systems with many degrees of freedom are subject to a bound on the rate of onset of chaos, including a bound on the Lyapunov exponent, λ{sub L}≤2π/β. We harness this bound to constrain the space of putative holographic CFTs and their would-be dual theories of AdS gravity. First, by studying out-of-time-order four-point functions, we discuss how λ{sub L}=2π/β in ordinary two-dimensional holographic CFTs is related to properties of the OPE at strong coupling. We then rule out the existence of unitary, sparse two-dimensional CFTs with large central charge and a set of higher spin currents of bounded spin; this implies the inconsistency of weakly coupled AdS{sub 3} higher spin gravities without infinite towers of gauge fields, such as the SL(N) theories. This fits naturally with the structure of higher-dimensional gravity, where finite towers of higher spin fields lead to acausality. On the other hand, unitary CFTs with classical W{sub ∞}[λ] symmetry, dual to 3D Vasiliev or hs[λ] higher spin gravities, do not violate the chaos bound, instead exhibiting no chaos: λ{sub L}=0. Independently, we show that such theories violate unitarity for |λ|>2. These results encourage a tensionless string theory interpretation of the 3D Vasiliev theory.

Automatic bounding estimation in modified NLMS algorithm

International Nuclear Information System (INIS)

Shahtalebi, K.; Doost-Hoseini, A.M.

2002-01-01

Modified Normalized Least Mean Square algorithm, which is a sign form of Nlm based on set-membership (S M) theory in the class of optimal bounding ellipsoid (OBE) algorithms, requires a priori knowledge of error bounds that is unknown in most applications. In a special but popular case of measurement noise, a simple algorithm has been proposed. With some simulation examples the performance of algorithm is compared with Modified Normalized Least Mean Square

Influence of nanosizing on hydrogen electrosorption properties of rhodium based nanoparticles/carbon composites

International Nuclear Information System (INIS)

Cachet-Vivier, Christine; Bastide, Stéphane; Zlotea, Claudia; Oumellal, Yassine; Laurent, Michel; Latroche, Michel

2017-01-01

Highlights: • Rh nanohydride (1.3–2.3 nm) investigated by cyclic voltammetry in the hydrogen domain. • An isopotential point characteristic of surface dehydrogenation is observed on cycling. • Upon cycling, the nanoparticle surface converts from RhH x to Rh. • The amount of sorbed H increases with nanoparticle downsizing, H/Rh = 0.47 at 1.3 nm. • Nanoparticle downsizing creates new multi-fold adsorption (sub)surface sites for H upd - Abstract: Composites made of ultra-small Rh hydride nanoparticles (NP) with controlled average sizes of 1.3, 1.9 and 2.3 nm dispersed in high surface area graphite powders were synthesized. The hydrogen electrosorption properties of the Rh nanohydride that is stable under ambient conditions were characterized by cyclic voltammetry under various scan rates in the hydrogen potential domain with the help of a cavity microelectrode. During the first cycles, an evolution of the voltammograms, characterized by an isopotential point, is observed that corresponds to a surface conversion of RhH x into Rh, the core of the NP remaining in the hydride phase. After stabilization, the voltammograms exhibit the classical hydrogen electrosoprtion peaks of Rh, but a shift to positive potentials indicates that H is more weakly bounded to the surface as the NP size decreases. The onset of the HER follows the same trend. Interestingly, it is observed that the quantity of electrosorbed hydrogen strongly increases when downsizing the NPs, with the H/Rh ratio reaching 0.47 ± 0.11 for NPs with an average size of 1.3 nm. This enhancement cannot be explained just by the increase in surface area by NP downsizing. It may arise from the creation of new multi-fold adsorption surface and sub-surface sites due to the presence of many corner and edge atoms in ultra-small NPs with strong surface curvature.

Lower Bounds for External Memory Dictionaries

DEFF Research Database (Denmark)

Brodal, Gerth Stølting; Fagerberg, Rolf

2003-01-01

We study trade-offs between the update time and the query time for comparison based external memory dictionaries. The main contributions of this paper are two lower bound trade offs between the I/O complexity of member queries and insertions: If N < M insertions perform at most δ · N/B I/Os, then......We study trade-offs between the update time and the query time for comparison based external memory dictionaries. The main contributions of this paper are two lower bound trade offs between the I/O complexity of member queries and insertions: If N

Quantum engine efficiency bound beyond the second law of thermodynamics.

Science.gov (United States)

Niedenzu, Wolfgang; Mukherjee, Victor; Ghosh, Arnab; Kofman, Abraham G; Kurizki, Gershon

2018-01-11

According to the second law, the efficiency of cyclic heat engines is limited by the Carnot bound that is attained by engines that operate between two thermal baths under the reversibility condition whereby the total entropy does not increase. Quantum engines operating between a thermal and a squeezed-thermal bath have been shown to surpass this bound. Yet, their maximum efficiency cannot be determined by the reversibility condition, which may yield an unachievable efficiency bound above unity. Here we identify the fraction of the exchanged energy between a quantum system and a bath that necessarily causes an entropy change and derive an inequality for this change. This inequality reveals an efficiency bound for quantum engines energised by a non-thermal bath. This bound does not imply reversibility, unless the two baths are thermal. It cannot be solely deduced from the laws of thermodynamics.

Capacity bounds for parallel IM-DD optical wireless channels

KAUST Repository

Chaaban, Anas; Rezki, Zouheir; Alouini, Mohamed-Slim

2016-01-01

A system consisting of parallel intensity-modulation direct-detection optical wireless channels with a total average intensity constraint is studied. Capacity upper and lower bounds for this system are derived. If channel-state information is available at the transmitter, the bounds have to be optimized with respect to intensity allocation over the parallel channels. The optimization of the lower bound is non-convex, however, the Karush-Kuhn-Tucker conditions can be used to find a list of possible solutions one of which is optimal. The optimal solution can then be found by an exhaustive search algorithm, which is computationally expensive. To overcome this, we propose a low-complexity intensity allocation algorithm which is nearly optimal. The optimized capacity lower bound coincides with the capacity at high signal-to-noise ratio. © 2016 IEEE.

Capacity bounds for parallel IM-DD optical wireless channels

KAUST Repository

Chaaban, Anas

2016-07-26

A system consisting of parallel intensity-modulation direct-detection optical wireless channels with a total average intensity constraint is studied. Capacity upper and lower bounds for this system are derived. If channel-state information is available at the transmitter, the bounds have to be optimized with respect to intensity allocation over the parallel channels. The optimization of the lower bound is non-convex, however, the Karush-Kuhn-Tucker conditions can be used to find a list of possible solutions one of which is optimal. The optimal solution can then be found by an exhaustive search algorithm, which is computationally expensive. To overcome this, we propose a low-complexity intensity allocation algorithm which is nearly optimal. The optimized capacity lower bound coincides with the capacity at high signal-to-noise ratio. © 2016 IEEE.

Self-colored nanoparticles containing naphthalene-bisimide derivatives: Synthesis and protein adsorption study

Energy Technology Data Exchange (ETDEWEB)

Polpanich, Duangporn, E-mail: duangporn@nanotec.or.th [National Nanotechnology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120 (Thailand); Asawapirom, Udom; Thiramanas, Raweewan; Piyakulawat, Phimwipha [National Nanotechnology Center, National Science and Technology Development Agency, Thailand Science Park, Pathumthani 12120 (Thailand)

2011-09-15

Highlights: {yields} Novel polymerizable naphthalene-bisimide dyes were designed and synthesized. {yields} Highly monodispersed self-colored nanoparticles were successfully prepared. {yields} Good colloidal stability of the nanoparticles was achieved after protein adsorption. - Abstract: An approach to covalently bound the novel polymerizable dyes, 2,3,6,7-tetrathienyl-1,4,5,8-naphthalenetetracarboxylic-N,N' -di(2-methylallyl)-bisimide (ALN4T) and 2,3,6,7-tetra(2,2'-bithiophene)-1,4,5,8-naphthalenetetracarboxylic-N,N' -di(2-methylallyl)-bisimide (ALN8T), and vinyl monomers for tailoring the self-colored nanoparticles (NPs) was demonstrated. Using the miniemulsion polymerization technique, the NPs with high conversion were synthesized. Examining the particles by scanning electron micrograph (SEM) revealed a uniform size distribution. UV/vis spectroscopy results showed that the colored NPs comprising of ALN4T exhibited the same absorption maxima compared to that of the parent dye, while a hypsochromic shift was observed when using ALN8T. By using bovine serum albumin (BSA) as a model, the amount of protein adsorption ({Gamma}{sub ads}) onto the surface of the colored NPs was evaluated. The {Gamma}{sub ads} on the colored NPs was found to be dictated by synergistic effects of the conformation change of BSA at a given pH and the electrostatic interaction between the protein and the particle surface. The good colloidal stability of the NPs after BSA adsorption was observed by zeta potential measurement. Therefore, the prepared self-colored NPs have potential application in biomedical areas.

Antimicrobial activity of silver nanoparticles encapsulated in poly-N-isopropylacrylamide-based polymeric nanoparticles.

Science.gov (United States)

Qasim, Muhammad; Udomluck, Nopphadol; Chang, Jihyun; Park, Hansoo; Kim, Kyobum

2018-01-01

In this study, we analyzed the antimicrobial activities of poly- N -isopropylacrylamide (pNIPAM)-based polymeric nanoparticles encapsulating silver nanoparticles (AgNPs). Three sizes of AgNP-encapsulating pNIPAM- and pNIPAM-NH 2 -based polymeric nanoparticles were fabricated. Highly stable and uniformly distributed AgNPs were encapsulated within polymeric nanoparticles via in situ reduction of AgNO 3 using NaBH 4 as the reducing agent. The formation and distribution of AgNPs was confirmed by UV-visible spectroscopy, transmission electron microscopy, and inductively coupled plasma optical emission spectrometry, respectively. Both polymeric nanoparticles showed significant bacteriostatic activities against Gram-negative ( Escherichia coli ) and Gram-positive ( Staphylococcus aureus ) bacteria depending on the nanoparticle size and amount of AgNO 3 used during fabrication.

Culture-bound syndromes in Hispanic primary care patients.

Science.gov (United States)

Bayles, Bryan P; Katerndahl, David A

2009-01-01

We sought to document Hispanic primary care patients' knowledge and experience of five culture-bound syndromes (CBS), as well as the basic socio-cultural correlates of these disorders. A convenience sample of 100 adult Hispanic patients presenting in an urban South Texas primary care clinic was recruited to complete a brief cross-sectional survey, presented in an oral format. Interviews sought information concerning five culture-bound syndromes--susto, empacho, nervios, mal de ojo, and ataques de nervios. Additional demographic, socio-economic, and acculturation data was collected. Descriptive and bivariate statistics (chi square, Fisher's) were used to assess relationships among variables and experience with each CBS. A multivariate logistic analysis was conducted to determine the possible contributions of age, gender, acculturation, and education to the personal experience of a culture-bound syndrome. Results indicate that 77% of respondents had knowledge of all five syndromes, with 42% reporting having personally experienced at least one CBS. Nervios was the most commonly suffered disorder, being reported by 30 respondents. This was followed, in declining order ofprevalence, by susto, mal de ojo, empacho, and ataques de nervios. Multivariate logistic regression analysis found that higher education beyond high school was associated with a slightly decreased likelihood of reporting having suffered from any culture-bound syndrome. While co-occurrence among these disorders occurred, the patterns of predictors suggest that the co-occurrence is not a reflection of mislabeling of one common syndrome. Knowledge of and experience with culture-bound syndromes is common among Hispanic primary care patients in South Texas. Healthcare providers ought to consider discussing these illnesses in a non-judgmental manner with patients who present with symptoms that are consistent with these syndromes. Future studies, with larger sample sizes, are warranted to elucidate the nature

Bounds of Certain Dynamic Inequalities on Time Scales

Directory of Open Access Journals (Sweden)

Deepak B. Pachpatte

2014-10-01

Full Text Available In this paper we study explicit bounds of certain dynamic integral inequalities on time scales. These estimates give the bounds on unknown functions which can be used in studying the qualitative aspects of certain dynamic equations. Using these inequalities we prove the uniqueness of some partial integro-differential equations on time scales.

O3 Nanoparticles

KAUST Repository

Wang, Juan

2016-11-16

Ti2O3 nanoparticles with high performance of photothermal conversion are demonstrated for the first time. Benefiting from the nanosize and narrow-bandgap features, the Ti2O3 nanoparticles possess strong light absorption and nearly 100% internal solar–thermal conversion efficiency. Furthermore, Ti2O3 nanoparticle-based thin film shows potential use in seawater desalination and purification.

Bounds and enhancements for negative scattering time delays

International Nuclear Information System (INIS)

Muga, J.G.; Egusquiza, I.L.; Damborenea, J.A.; Delgado, F.

2002-01-01

The time of passage of the transmitted wave packet in a tunneling collision of a quantum particle with a square potential barrier becomes independent of the barrier width in a range of barrier thickness. This is the Hartman effect, which has been frequently associated with 'superluminality'. A fundamental limitation on the effect is set by nonrelativistic 'causality conditions'. We demonstrate first that the causality conditions impose more restrictive bounds on the negative time delays (time advancements) when no bound states are present. These restrictive bounds are in agreement with a naive, and generally false, causality argument based on the positivity of the 'extrapolated phase time', one of the quantities proposed to characterize the duration of the barrier's traversal. Nevertheless, square wells may in fact lead to much larger advancements than square barriers. We point out that close to the thresholds of new bound states, the time advancement increases considerably, while, at the same time, the transmission probability is large, which facilitates the possible observation of the enhanced time advancement

Two-nucleon bound states in quenched lattice QCD

International Nuclear Information System (INIS)

Yamazaki, T.; Kuramashi, Y.; Ukawa, A.

2011-01-01

We address the issue of bound state in the two-nucleon system in lattice QCD. Our study is made in the quenched approximation at the lattice spacing of a=0.128 fm with a heavy quark mass corresponding to m π =0.8 GeV. To distinguish a bound state from an attractive scattering state, we investigate the volume dependence of the energy difference between the ground state and the free two-nucleon state by changing the spatial extent of the lattice from 3.1 fm to 12.3 fm. A finite energy difference left in the infinite spatial volume limit leads us to the conclusion that the measured ground states for not only spin triplet but also singlet channels are bounded. Furthermore the existence of the bound state is confirmed by investigating the properties of the energy for the first excited state obtained by a 2x2 diagonalization method. The scattering lengths for both channels are evaluated by applying the finite volume formula derived by Luescher to the energy of the first excited states.

Structure and magnetic properties of Cr nanoparticles and Cr2O3 nanoparticles

International Nuclear Information System (INIS)

Zhang, W.S.; Brueck, E.; Zhang, Z.D.; Tegus, O.; Li, W.F.; Si, P.Z.; Geng, D.Y.; Buschow, K.H.J.

2005-01-01

We have synthesized Cr nanoparticles by arc-discharge and Cr 2 O 3 nanoparticles by subsequent annealing the as-prepared Cr nanoparticles. The structure of these nanoparticles is studied by means of X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscope. Most of the particles show a good crystal habit of well-defined cubic or orthorhombic shape, while some small particles show spherical shape. The as-prepared Cr nanoparticles have a BCC Cr core coated with a thin Cr 2 O 3 layer. Cr in the core of the particles heated at 873 K for 4 h is changed to Cr 2 O 3 . The results of magnetic measurements show that the Cr nanoparticles exhibit mainly antiferromagnetic properties, in addition to a weak-ferromagnetic component at lower fields. The weak-ferromagnetic component may be ascribed to uncompensated surface spins. For the field-cooled Cr 2 O 3 nanoparticles, an exchange bias is observed in the hysteresis loops, which can be interpreted as the exchange coupling between the uncompensated spins at the surface and the spins in the core of the Cr 2 O 3 nanoparticles

Output controllability of nonlinear systems with bounded control

International Nuclear Information System (INIS)

Garcia, Rafael; D'Attellis, Carlos

1990-01-01

The control problem treated in this paper is the output controllability of a nonlinear system in the form: x = f(x) + g(x)u(t); y = h(x), using bounded controls. The approach to the problem consists of a modification in the system using dynamic feedback in such a way that the input/output behaviour of the closed loop matches the input/output behaviour of a completely output-controllable system with bounded controls. Sufficient conditions are also put forward on the system so that a compact set in the output space may be reached in finite time using uniformally bounded controls, and a result on output regulation in finite time with asymptotic state stabilization is obtained. (Author)

Malabsorption of protein bound vitamin B12.

OpenAIRE

Dawson, D W; Sawers, A H; Sharma, R K

1984-01-01

Patients with subnormal serum vitamin B12 concentrations were tested for absorption of protein bound vitamin B12 and compared with controls. Absorption of the protein bound vitamin appeared to decrease with increasing age in healthy subjects. Differences between the result of this test and the result of the Schilling test in patients who had undergone gastric surgery were confirmed; such differences were also seen in some patients who had iron deficiency anaemia, an excessive alcohol intake, ...

New Spectral Features from Bound Dark Matter

DEFF Research Database (Denmark)

Catena, Riccardo; Kouvaris, Chris

2016-01-01

We demonstrate that dark matter particles gravitationally bound to the Earth can induce a characteristic nuclear recoil signal at low energies in direct detection experiments. The new spectral feature we predict can provide the ultimate smoking gun for dark matter discovery for experiments...... with positive signal but unclear background. The new feature is universal, in that the ratio of bound over halo dark matter event rates at detectors is independent of the dark matter-nucleon cross section....

Antimicrobial active silver nanoparticles and silver/polystyrene core-shell nanoparticles prepared in room-temperature ionic liquid

International Nuclear Information System (INIS)

An Jing; Wang Desong; Luo Qingzhi; Yuan Xiaoyan

2009-01-01

Uniform silver nanoparticles and silver/polystyrene core-shell nanoparticles were successfully synthesized in a room temperature ionic liquid, 1-n-butyl-3-methylimidazolium tetrafluoroborate ([BMIM].BF 4 ). [BMIM].BF 4 plays a protective role to prevent the nanoparticles from aggregation during the preparation process. Transmission electron micrographs confirm that both silver nanoparticles and core-shell nanoparticles are regular spheres with the sizes in the range of 5-15 nm and 15-25 nm, respectively. The X-ray diffraction analysis reveals the face-centered cubic geometry of silver nanoparticles. The as-prepared nanoparticles were also characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy. In addition, antimicrobial activities against E. coli and S. aureus were studied and the results show that both silver nanoparticles and core-shell nanoparticles possess excellent antimicrobial activities. The antimicrobial mechanism of the as-prepared nanoparticles was discussed.

On functions of bounded semivariation

Czech Academy of Sciences Publication Activity Database

Monteiro, Giselle Antunes

2015-01-01

Roč. 40, č. 2 (2015), s. 233-276 ISSN 0147-1937 Institutional support: RVO:67985840 Keywords : semivariation * functions of bounded variation * regulated functions Subject RIV: BA - General Mathematics http://projecteuclid.org/euclid.rae/1491271216

Faddeev-Yakubovsky technique for weakly bound systems

International Nuclear Information System (INIS)

Hadizadeh, M.R.; Yamashita, M.T.; Tomio, Lauro; Delfino, A.

2011-01-01

Nature shows the existence of weakly bound systems in different sectors, ranging from atomic to nuclear physics. Few-body systems with large scattering length exhibit universal features, which are independent of the details of the interaction, and thus are common to nuclear and atomic systems. Very different methods are used to study the properties of few-body systems, from Faddeev methods to diagonalization methods that rely on an expansion of the wave functions in a complete basis set, like e.g. hyper-spherical harmonics and no core shell model. In this talk we present Faddeev-Yakubovsky method to study the three- and four-body bound states in momentum space. To show the efficiency and accuracy of the method we investigate the three- and four-boson weakly bound states in unitary limit (for zero two-body binding) and we present a pretty complete picture of universality. (author)

Bound values for Hall conductivity of heterogeneous medium under ...

Indian Academy of Sciences (India)

- ditions in inhomogeneous medium has been studied. It is shown that bound values for. Hall conductivity differ from bound values for metallic conductivity. This is due to the unusual character of current percolation under quantum Hall effect ...

Lower Bounds for Number-in-Hand Multiparty Communication Complexity, Made Easy

DEFF Research Database (Denmark)

Phillips, Jeff; Verbin, Elad; Zhang, Qin

2012-01-01

; the technique seems applicable to a wide range of other problems as well. The obtained communication lower bounds imply new lower bounds in the functional monitoring model [11] (also called the distributed streaming model). All of our lower bounds allow randomized communication protocols with two-sided error......In this paper we prove lower bounds on randomized multiparty communication complexity, both in the blackboard model (where each message is written on a blackboard for all players to see) and (mainly) in the message-passing model, where messages are sent player-to-player. We introduce a new...... technique for proving such bounds, called symmetrization, which is natural, intuitive, and often easy to use. For example, for the problem where each of k players gets a bit-vector of length n, and the goal is to compute the coordinate-wise XOR of these vectors, we prove a tight lower bounds of Ω...

Reply to ''Limitation on numerical bounds on transition probabilities''

International Nuclear Information System (INIS)

Storm, D.

1975-01-01

It is demonstrated that a good share of the error Shakeshaft attributes to the failure to account for ionization in customary impact-parameter calculations for proton--hydrogen-atom scattering amplitudes really results from the inadequacy of the traveling hydrogenic basis set to account for the dynamic polarization of the hydrogen atom by the moving proton. The lower limit for the first-order bound can be reduced by using hydrogenlike basis functions that allow for this polarization. Bounds on the cross sections obtained by using the bound Δ 1 need not be infinite. The inclusion of time-dependent adjustable parameters in the basis functions provides a method for modifying the projection of the deviation vector or error term in the Schroedinger equation in the continuum. The exploratory work of Storm and Rapp appears to offer hope that reasonably accurate bounds on at least the 1s charge-exchange amplitudes and cross sections can be obtained by employing only square-integrable basis functions that contain time-dependent variable parameters. However, if it is necessary to account for the flux in the ionization channels, it is shown that an account could be made without the bound becoming infinite

Upper bounds on the number of errors corrected by a convolutional code

DEFF Research Database (Denmark)

Justesen, Jørn

2004-01-01

We derive upper bounds on the weights of error patterns that can be corrected by a convolutional code with given parameters, or equivalently we give bounds on the code rate for a given set of error patterns. The bounds parallel the Hamming bound for block codes by relating the number of error...

Room temperature ferromagnetism and absorption red-shift in nitrogen-doped TiO2 nanoparticles

International Nuclear Information System (INIS)

Gómez-Polo, C.; Larumbe, S.; Monge, M.

2014-01-01

Highlights: • N-doped TiO 2 anatase nanoparticles were obtained by sol–gel. • The nanoparticle size, controlled by the N doping, determines lattice parameters. • Correlation between room temperature ferromagnetism and absorption red-shift. • Oxygen vacancies reinforce both phenomena. • Metal transition impurities contribute to the room temperature ferromagnetism. - Abstract: In this work, room-temperature ferromagnetism and the red-shift of the optical absorption is analyzed in nitrogen doped TiO 2 semiconductor nanoparticles. The nanoparticles were synthesized by the sol–gel method using urea as the nitrogen source. Titanium Tetraisopropoxide (TTIP) was employed as the alkoxyde precursor and dissolved in ethanol. The as prepared gels were dried and calcined in air at 300 °C. Additionally, post-annealing treatments under vacuum atmosphere were performed to modify the oxygen stoichiometry of the samples. The anatase lattice parameters, analyzed by means of powder X-ray diffractometry, depend on the nanometer grain size of the nanoparticles (increase and decrease, respectively, of the tetragonal a and c lattice parameters with respect to the bulk values). The diffuse reflectance ultraviolet–visible (UV–Vis) absorbance spectra show a clear red-shift as consequence of the nitrogen and the occurrence of intragap energy levels. The samples display ferromagnetic features at room temperature that are reinforced with the nitrogen content and after the post annealings in vacuum. The results indicate a clear correlation between the room temperature ferromagnetism and the shift of the absorbance spectrum. In both phenomena, oxygen vacancies (either induced by the nitrogen doping or by the post vacuum annealings) play a dominant role. However, we conclude the existence of very low concentration of diluted transition metal impurities that determine the room ferromagnetic response (bound magnetic polaron BMP model). The contraction of the c soft axis of the