bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging With Nature: Compressive Imaging Using a Multiply Scattering Medium
Authors: Liutkus Antoine , Martina David , Popoff Sébastien , Chardon Gilles , Katz Ori , Lerosey Geoffroy , Gigan Sylvain , Daudet Laurent , Carron Igor
Published: July 2014

The recent theory of compressive sensing leverages upon the structure of signals to acquire them with much fewer measurements than was previously thought necessary and certainly well below the traditional Nyquist-Shannon sampling rate. However, most implementations developed to take advantage of this framework revolve around controlling the measurements with carefully engineered material or acquisition sequences. Instead, we use the natural randomness of wave propagation through multiply scattering media as an optimal and instantaneous compressive imaging mechanism. Waves reflected from an object are detected after propagation through a well-characterized complex medium. Each local measurement thus contains global information about the object, yielding a purely analog compressive sensing method. We experimentally demonstrate the effectiveness of the proposed approach for optical imaging by using a 300-micrometer thick layer of white paint as the compressive imaging device. Scattering media are thus promising candidates for designing efficient and compact compressive imagers.
Sodium. Its Role in Bacterial Metabolism
Authors: Ito Masahiro , Barquera Blanca
Published: July 2014

This chapter reviews the multiple roles of the sodium ion Na+ in the physiology of bacteria. Virtually all cells need to extrude Na+ in order to maintain a constant internal environment. In many bacteria, transport of Na+ out of the cell has an important additional role in harnessing energy and distributing it within the cell. In these cases, Na+ takes on the role otherwise played by H+ in chemiosmotic energetic functions. As a means of exploring these functions, we will examine a subset of Na+ transport enzymes that are prototypical of the various catalytic processes involved in Na+ homeostasis and Na+ chemiosmosis.
Potassium
Authors: Miller David M. , Gulbis Jacqueline M.
Published: July 2014

Potassium is an essential mineral nutrient present in all organisms as the monovalent cation K+. The coordination chemistry of ionic potassium governs its physiological interactions, underpinning electrical excitability in nerve and muscle as well as electrolyte balance, blood pressure, cell volume regulation and downstream metabolic processes. The common link between these functions is the establishment and maintenance of a membrane potential. To retain membrane excitability, intracellular and extracellular K+ concentrations must be maintained within stringent limits. A failure to adequately regulate K+ levels can have dire physiological consequences under the broad umbrellas of hypo- and hyper-kalaemia. In multicellular organisms, K+ homeostasis entails both short- and long-term measures. Homeostatic processes involve interplay between ion channels and co-transporters differentially expressed in specific cell types or tissues. In the human central nervous system, for example, K+ uptake and spatial buffering mechanisms enable reinstatement of the membrane potential following action potentials. Electroneutrality is maintained by a complex balancing act between electrolyte species. In prokaryotes, the ability to actively accumulate K+ and maintain a potential driving force across the periplasmic membrane is critical to cellular integrity, cell volume regulation, cellular morphology, cell division, pH sensing and possibly intercellular communication.
Magnesium
Authors: Romani Andrea M. P.
Published: July 2014

Magnesium ions play an important role in cell biology. Cellular magnesium homeostasis responds to the same basic tenets in both prokaryotes and eukaryotes. Total cellular Mg2+ content is maintained below the concentration predicted by its electrochemical equilibrium and cellular free Mg2+ content is slightly below the concentration present in the extracellular environment. A similar modest gradient is present between the cytoplasm and the mitochondrial matrix or the lumen of the endoplasmic reticulum. In plant cells and eukaryotes, the distribution of Mg2+ within the cytoplasm and cellular organelles is well defined and Mg2+ homeostasis is tightly regulated through a combination of transport and chelating mechanisms. All organisms require adequate cellular Mg2+ levels to regulate the activity of numerous enzymes, channels and genes that directly and indirectly control metabolic and bioenergetics processes. Dynamic changes in total and free Mg2+ concentrations have been observed in both prokaryotes and eukaryotes following environmental, metabolic and hormonal variations. Although the changes in free Mg2+ concentrations are small in percentage terms compared to those of Ca2+, they are still of an amplitude sufficient to modulate the activity of the various cellular enzymes and processes. At the molecular level, our knowledge of Mg2+ transporters is more advanced in prokaryotes than in eukaryotes, although several of the transporters identified in prokaryotes have orthologues in both plant and mammalian cells. In eukaryotes, ATP and cAMP are essential chelating and regulating agents for Mg2+. Cyclic-AMP, especially, plays a key role in coordinating the effect of Mg2+ on cell metabolism and bioenergetics. Taken together, these pieces of evidence suggest an essential, albeit often underappreciated, role for Mg2+ as a key regulator of metabolic and cellular processes. Mounting clinical and experimental evidence further underlies the importance of this regulatory role in certain pathological conditions and diseases in humans, animals and plants alike.
Chromium
Authors: Lay Peter A. , Levina Aviva
Published: July 2014

Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.
Molybdenum and Tungsten
Authors: Tejada-Jiménez Manuel , Schwarz Guenter
Published: July 2014

Molybdenum (Mo) is an essential micronutrient for the majority of organisms ranging from bacteria to animals. To fulfil its biological role, it is incorporated into a pterin-based Mo-cofactor (Moco) and can be found in the active centre of more than 50 enzymes that are involved in key reactions of carbon, nitrogen and sulfur metabolism. Five of the Mo-enzymes are present in eukaryotes: nitrate reductase (NR), sulfite oxidase (SO), aldehyde oxidase (AO), xanthine oxidase (XO) and the amidoxime-reducing component (mARC). Cells acquire Mo in form of the oxyanion molybdate using specific molybdate transporters. In bacteria, molybdate transport is an extensively studied process and is mediated mainly by the ATP-binding cassette system ModABC. In contrast, in eukaryotes, molybdate transport is poorly understood since specific molybdate transporters remained unknown until recently. Two rather distantly related families of proteins, MOT1 and MOT2, are involved in eukaryotic molybdate transport. They each feature high-affinity molybdate transporters that regulate the intracellular concentration of Mo and thus control activity of Mo-enzymes. The present chapter presents an overview of the biological functions of Mo with special focus on recent data related to its uptake, binding and storage.
Iron in Eukarya
Authors: Sharp Paul
Published: July 2014

Iron is essential for the normal physiological function of all organisms. In humans it is required for a plethora of biochemical roles including the transport of oxygen in the blood and energy production in the mitochondria. However, iron is also highly cytotoxic when present at high levels as it readily participates in oxidation-reduction reactions that lead to the generation of reactive oxygen species. One unique feature of iron biology is the lack of excretory mechanisms to remove excess iron from the body. Therefore, the concerted action of several genes and proteins working together to regulate the movement of iron across cell membranes, its storage in peripheral tissues and its physiological utilization in the body is essential for maintaining iron homeostasis. Humans are exposed to iron in a number of chemical forms (haem or non-haem; ferric or ferrous). This chapter will describe how humans acquire iron from their diet; the subsequent delivery of iron to its sites of utilization and storage; and how iron is recycled from effete erythrocytes for re-use in metabolism. Mutations in a number of the genes controlling iron metabolism have been identified and study of the pathological consequences of these mutations has allowed us to gain a greater understanding of how the body senses changes in iron status and coordinates its transport, storage and utilization to maintain homeostasis.
Copper in Eukaryotes
Authors: Blackburn Ninian J. , Yan Nan , Lutsenko Svetlana
Published: July 2014

Copper is essential for normal growth and development of eukaryotic organisms. Numerous physiological processes rely on sufficient availability of copper: from indispensable reactions such as mitochondrial respiration to more highly specialized processes such as pigment development in a skin. Copper misbalance has been linked to a variety of metabolic and neurodegenerative disorders in humans. Complex cellular machinery has evolved to mediate copper uptake, compartmentalization and incorporation into target proteins. Extensive studies revealed a predominant utilization of methionines and histidines by copper handling molecules for copper capture at the extracellular surface and delivery to cuproenzymes in the lumen of cellular compartments, respectively. Cu(I) is a predominant form within the cell, and copper binding and distribution inside the cell at the cytosolic sites relies heavily on cysteines. The selectivity and directionality of copper transfer reactions is determined by thermodynamic and kinetic factors as well as spatial distribution of copper donors and acceptors. In this chapter, we review current structural and mechanistic data on copper transport and distribution in yeast and mammalian cells and highlight important issues and questions for future studies.
Zinc
Authors: Hogstrand Christer , Fu Dax
Published: July 2014

Zinc(II) is essential to life. It is involved in biological processes as cofactor of proteins, and as signalling ion. This demands a precise control of zinc movements and concentrations. In vertebrates, zinc transport across lipid bilayers is mediated principally by two protein families, ZNT (SLC30) and ZIP (SLC39). These proteins are ubiquitously present among organisms and unique insight into the mechanism of Zn2+ translocation comes from studies of the Escherichia coli SLC30 homologue, Yiip, the structure of which has been determined at 2.9 Å resolution. Here we emphasize the structure-function relationship of YiiP as it mediates the journey of Zn2+ across the membrane. Zinc also permeates cell membranes through calcium channels and, in prokaryotes, plants and fungi, by the aid of P-type ATPases. ZIP proteins can mediate gated flux of free zinc into the cytosol and the resulting zinc transients modulate cell signalling networks, and in particular pathways involved in cell proliferation, migration and differentiation. A slower genomic effect of elevated cytosolic free zinc concentrations occurs through a zinc-responsive transcription factor, MTF1. There is also a dynamic binding and release of zinc from metallothioneins that completes an intricate system to regulate this biologically active trace metal.
Cadmium
Authors: Moulis Jean-Marc , Bourguignon Jacques , Catty Patrice
Published: July 2014

Cadmium is not an essential element for life. It is geologically marginal but anthropogenic activities have contributed significantly to its dispersion in the environment and to cadmium exposure of living species. The natural speciation of the divalent cation Cd2+ is dominated by its high propensity to bind to sulfur ligands, but Cd2+ may also occupy sites providing imidazole and carboxylate ligands. It binds to cell walls by passive adsorption (bio-sorption) and it may interact with surface receptors. Cellular uptake can occur by ion mimicry through a variety of transporters of essential divalent cations, but not always. Once inside cells, Cd2+ preferentially binds to thiol-rich molecules. It can accumulate in intracellular vesicles. It may also be transported over long distances within multicellular organisms and be trapped in locations devoid of efficient excretion systems. These locations include the renal cortex of animals and the leaves of hyper-accumulating plants. No specific regulatory mechanism monitors Cd2+ cellular concentrations. Thiol recruitment by cadmium is a major interference mechanism with many signalling pathways that rely on thiolate-disulfide equilibria and other redox-related processes. Cadmium thus compromises the antioxidant intracellular response that relies heavily on molecules with reactive thiolates. These biochemical features dominate cadmium toxicity, which is complex because of the diversity of the biological targets and the consequent pleiotropic effects. This chapter compares the cadmium-handling systems known throughout phylogeny and highlights the basic principles underlying the impact of cadmium in biology.
Mercury
Authors: Fretham Stephanie J. B. , Aschner Michael
Published: July 2014

Mercury (Hg) is a non-essential, naturally occurring metal with many industrial uses. Most forms of Hg are highly toxic to both prokaryotic and eukaryotic organisms. There are no known biological proteins or processes that require Hg; however, unlike most non-essential metals, several protein-based processes have evolved to aid in Hg detoxification. This chapter outlines and discusses the mechanisms by which Hg enters and is handled by cells. In particular, similarities and differences between the effects of elemental and ionic Hg are highlighted in both prokaryotic and eukaryotic cells. The processes involved include Hg resistance, transport mechanisms, cellular distribution, and detoxification.
Antimony and Bismuth
Authors: Cheng Tianfan , Sun Hongzhe
Published: July 2014

Antimony and bismuth are in Group 15 of the periodic table. They display important impacts on biological systems and are being used as components of anti-parasitic, antimicrobial or anti-cancer drugs. In this chapter, the general scenarios of binding and transport of antimony (as Sb(III) and Sb(V)) and bismuth (as Bi(III)) in biological systems are summarized. Both can be biomethylated by different mechanisms, including enzymatic catalysis. Antimonate (Sb(V)) can be reduced to the more toxic antimonite (Sb(III)), both enzymatically and non-enzymatically. Sb(III) transporters are ubiquitously present in organisms as aquaglyceroporin protein channels. To acquire resistance to antimony, organisms rely on several protein systems that extrude intracellular antimony. Selected antimony-binding proteins have been identified and structurally characterized and more can be identified by proteomic approaches. Binding of Bi(III) to proteins and enzymes offers information on transport of the metal ions in biological systems. Further work is required to uncover their medicinal potentials as well as understand their toxicity.
Lead
Authors: Cangelosi Virginia M. , Pecoraro Vincent L.
Published: July 2014

Lead (Pb) has been recognized as a human toxin for thousands of years. In biological systems, sulfur-, oxygen- and nitrogen-containing groups coordinate lead in a variety of geometries. Upon ingestion by humans, lead is absorbed through the stomach, released into the blood and coordinated by glutathione and a variety of zinc and calcium proteins including δ-aminolevulinic acid dehydratase (ALAD), zinc finger transcription factors and calmodulin. Metal substitution and indiscriminate binding to proteins causes a loss of function, reflected in the diverse symptoms of lead poisoning. Although some lead binding proteins are induced in the presence of lead, their role in detoxification in humans is unclear. However, several types of bacteria have evolved defence mechanisms for the uptake, storage and exportation of lead. The proteins involved in regulating these defences, such as PbrR, are extremely selective for lead.
Microwave-assisted aqueous synthesis of Mn-doped ZnS quantum dots and their room-temperature phosphorescence detection of indapamide
Authors: Zhu Dong , Li Wei , Wen Hong-Mei , Chen Qian , Ma Li , Hu Yue
Published: July 2014

High-quality Mn-doped ZnS QDs were prepared using a green and rapid microwave-assisted synthetic approach in an aqueous solution, which were used for room-temperature phosphorescence (RTP) detection of indapamide.
Electrochemical determination of selected neurotransmitters at electrodes modified with oppositely charged carbon nanoparticles
Authors: Kundys Magdalena , Szot Katarzyna , Rozniecka Ewa , Jönsson-Niedziółka Martin , Lawrence Ruth , Bull Steven D. , Marken Frank , Opallo Marcin
Published: July 2014

The electrocatalytic oxidation of neurotransmitters on the electrodes modified with oppositely charged carbon nanoparticles has been investigated.
Green synthesis of gold nanoparticles with willow tree bark extract: a sensitive colourimetric sensor for cysteine detection
Authors: Bahram Morteza , Mohammadzadeh Esmat
Published: July 2014

In this work we report an easy and simple green synthesis method for gold nanoparticles (GNPs) using willow tree bark extract.
Gold-plated magnetic polymers for highly specific enrichment and label-free detection of blood biomarkers under physiological conditions
Authors: Kwon Seung-Ryong , Jeon Chang Su , Hong Nam Young , Kim Kwang Pyo , Hwang Inseong , Chung Taek Dong
Published: July 2014

Highly efficient prevention of nonspecific binding by gold-plated magnetic polymer microspheres enables bead-based label-free assays using MADLI MS under physiological conditions.
Preparation of recoverable Fe3O4@PANI–PdII core/shell catalysts for Suzuki carbonylative cross-coupling reactions
Authors: Zhu Xiaohang , Niu Jianrui , Zhang Fengwei , Zhou Jinghui , Li Xinzhe , Ma Jiantai
Published: July 2014

We report on the synthesis, characterization and catalytic performance of a palladium-based superparamagnetic catalyst of Fe3O4@polyaniline core/shell microspheres (Fe3O4@PANI–PdII).
Fluorinated low band gap copolymer based on dithienosilole–benzothiadiazole for high-performance photovoltaic device
Authors: Lv Hongying , Zhao Xiaoli , Li Zidong , Yang Dalei , Wang Zhongliang , Yang Xiaoniu
Published: July 2014

The introduction of fluorine atom into a copolymer of dithienosilole–benzothiadiazole causes significant enhancement in the PSCs with the PCE increasing from 4.68% to 6.70%.
Hyperbranched polyester nanorods with pyrrolo[2,1-a]isoquinoline end groups for fluorescent recognition of Fe3+
Authors: Han Qiaorong , Jiang Yuliang , Jin Can , Cheng Shanshan , Wang Xiaoxia , Wang Xiangyu , Wang Bingxiang
Published: July 2014

Novel hyperbranched polyester nanorods HBPE-CICA6 and HBPE-CICA2 were obtained and used to establish a highly sensitive fluorescent sensor for Fe3+ ions.
Pd doped SiO2 nanoparticles: an efficient recyclable catalyst for Suzuki, Heck and Sonogashira reactions
Authors: Kotadia Deepali A. , Patel Urmila H. , Gandhi Sahaj , Soni Saurabh S.
Published: July 2014

Palladium doped silica (Pd/SiO2) mesoporous material was synthesized via a sol–gel route using the P123 triblock copolymer as structure directing agent. Pd/SiO2 was efficiently used as a catalyst for Suzuki, Heck and Sonogashira reactions under microwave irradiation. The catalyst exhibited high activity for all the coupling reactions and can be recycled nine times without a significant loss in its catalytic activity.
Synthesis of polyborosiloxane and its reversible physical crosslinks
Authors: Li Xufeng , Zhang Dian , Xiang Kewei , Huang Guangsu
Published: July 2014

A hybrid polyborosiloxane was synthesized and the effect of boron concentration on the Si–O : B weak bonding of polyborosiloxane was investigated mainly using FTIR and dynamic rheology.
Phosgene-free synthesis of polypeptides using activated urethane derivatives of α-amino acids: an efficient synthetic approach to hydrophilic polypeptides
Authors: Yamada Shuhei , Sudo Atsushi , Goto Mitsuaki , Endo Takeshi
Published: July 2014

Polypeptide synthesis has been successfully achieved through polycondensation of activated urethane derivatives with amines, accompanied by the elimination of phenol and CO2.
Microwave synthesis of high rate nanostructured LiMnBO3 with excellent cyclic behavior for lithium ion batteries
Authors: Karthikeyan Kaliyappan , Lee Yun Sung
Published: July 2014

LiMnBO3 nanobeads (LMB-NB) prepared using a urea assisted microwave irradiation method delivered 67 mA h g−1 capacity at 0.6 C rate between 1.25 and 4.8 V, showing 88% cyclability after 100 cycles.
Probing the importance of planar surfaces and crystal edges for electron transfer within iron-bearing clays
Authors: Wang Zhaohui
Published: July 2014

Clay with different binding environment of structural iron many differ in its mode of electron transfer from and to external electron donor/acceptor.
Shape recovery characteristics for shape memory polymers subjected to high intensity focused ultrasound
Authors: Li Guo , Fei Guoxia , Liu Bo , Xia Hesheng , Zhao Yue
Published: July 2014

A random copolymer shape memory behaviour triggered by high intensity focused ultrasound (HIFU) was studied in detail.
Synthesis, characterization, and visible-light photocatalytic activity of BiOI hierarchical flower-like microspheres
Authors: Liu Jingyi , Li Haiping , Du Na , Song Shue , Hou Wanguo
Published: July 2014

BiOI flower-like microspheres prepared using N(Bu)4I as iodine source and template exhibit high photocatalytic activity under visible light.
Centri-voltammetric dopamine detection
Authors: Cemgil Sultan Sinan , Sezer Esma , Tepeli Yudum , Anik Ulku
Published: July 2014

Centri-voltammetry is a novel method that combines centrifuge with voltammetry. In the present work centri-voltammetric detection of DA has been mad e for the first time.
PEI@Mg2SiO4: an efficient carbon dioxide and nitrophenol compounds adsorbing material
Authors: Chen Zheng-Yong , Gao Hong-Wen , Yang Jia-Xiang
Published: July 2014

PEI@Mg2SiO4: an efficient carbon dioxide and nitrophenol compounds adsorbing material.
3D printed modules for integrated microfluidic devices
Authors: Lee Kyoung G. , Park Kyun Joo , Seok Seunghwan , Shin Sujeong , Kim Do Hyun , Park Jung Youn , Heo Yun Seok , Lee Seok Jae , Lee Tae Jae
Published: July 2014

Direct 3d printing for functional modules and their assembly into an integrated microfluidic device.
Access to harmonine, a chemical weapon of ladybird beetles
Authors: Chandra Philkhana Satish , Dhasaiyan Prabhu , Prasad B. L. V. , Reddy D. Srinivasa
Published: July 2014

The synthesis of harmonine, a defense alkaloid from the harlequin ladybird is reported by three different routes.
Formation of quasi-mesocrystal ZnMn2O4 twin microspheres via an oriented attachment for lithium-ion batteries
Authors: Liu Yurong , Bai Jing , Ma Xiaojian , Li Jingfa , Xiong Shenglin
Published: July 2014

Quasi-mesocrystal ZnMn2O4 twin microspheres have been successfully prepared for the first time based on a distinctive oriented attachment accompanied by Ostwald ripening.
AIE-active, highly thermally and morphologically stable, mechanochromic and efficient solid emitters for low color temperature OLEDs
Authors: Gong Yongyang , Liu Jun , Zhang Yiren , He Gufeng , Lu Yang , Fan Wen Bin , Yuan Wang Zhang , Sun Jing Zhi , Zhang Yongming
Published: July 2014

Carefully designed AIE-active luminogens can be utilized to fabricate metal-free and non-doped low color temperature OLEDs.
Shell-thickness-dependent nonlinear optical properties of colloidal gold nanoshells
Authors: Gordel Marta , Olesiak-Banska Joanna , Kolkowski Radoslaw , Matczyszyn Katarzyna , Buckle Malcolm , Samoc Marek
Published: July 2014

Third-order nonlinear optical properties of gold nanoshells of different thickness were investigated over a broad wavelength range (530–1200 nm) by the Z-scan technique using femtosecond laser pulses.
Effect of Cu and PdCu wire bonding on bond pad splash
Authors: Tan Y.Y. , Sim K.S.
Published: July 2014

Cu wire bonding research has exploded exponentially in the past few years. Many studies have been carried out to understand the different behaviours of Cu wire and Au wire. One of the observations on Cu wire bonding is the excessive formation of aluminium (Al) splash on the bond pad due to a higher bond force. This leads to pad peeling and bond failure resulting in poor reliability performance of Cu and PdCu wire semiconductor devices. It is known that the Al splash is influenced by the front‐end pad metal process and back‐end wire bond process. Reported is the design of an experiment carried out to study a few factors that could influence the Al splash. The characterisation work is implemented to understand the bond pad structure using the focused ion beam (FIB) followed by a hardness test of bond pad metallisation. Then the mechanical cross‐section is taken to measure the Al splash in three different directions. The results show that Al splash can be controlled by optimising the bond pad thickness, hardness and additive for reliable Cu and PdCu wire bonding.
Differential broadband filter based on microstrip coupled line structures
Authors: Wang Xiao‐Hua , Hu Shen , Cao Qian‐Yu
Published: July 2014

A coupled line schematic is proposed to build the differential filter featuring broadband, low insertion loss and good common‐mode suppression. The proposed filter is composed of four quarter‐wavelength coupled lines and four quarter‐wavelength microstrip lines. The calculated, simulated and measured results are in good agreement with each other. The differential‐mode signal can propagate with low insertion loss, whereas the common‐mode signal will be suppressed below −10 dB. The fractional bandwidth of the proposed filter is 82% centred at 3 GHz.
Lentivirus-Mediated Knockdown of NOB1 Suppresses the Proliferation of Colon Cancer Cells
Authors: Liu Y. , Huang H. , Yuan B. , Zhuang L. Y. , Luo T. P. , Zhang Q.
Published: July 2014

NOB1 is important for ribosome biogenesis and protein degradation. Previous studies showed that it could regulate the growth and colony-formation ability of ovarian, breast and hepatocellular carcinoma cells. However, its function in colon cancer cells is largely unknown. In this study, we found that NOB1 could express in 6 different colon cancer cell lines. Lentivirus-mediated shRNA targeted NOB1 could suppress the endogenous gene expression. NOB1 depletion significantly inhibited cell proliferation and colony formation ability, as determined by MTT and colony formation assays. Flow cytometry analysis showed NOB1 silencing arrested cell cycle in G0 / G1 phase. Moreover, the percentage of cells at sub-G1 phase dramatically increased after NOB1 knockdown. These results indicate that NOB1 may play an important role in the growth and tumorigensis of colon cancer and knockdown of NOB1 may be a potential therapeutic method for colon cancer in the future.
Gallenwegserkrankungen im Alter
Authors: Heger E. , Lammert F. ,   für die Arbeitsgemeinschaft Geriatrische Gastroenterologie (AGGG) der Deutschen Gesellschaft für Verdauungs- und Stoffwechselkrankheiten (DGVS)
Published: July 2014

Durch Gallensteine bedingte Krankheiten treten in höherem Lebensalter häufiger auf. In dieser Kurzübersicht werden leitlinienbasierte Empfehlungen zur Diagnostik und Therapie bei Gallenwegserkrankungen im Alter zusammengefasst. Biliäre Koliken stellen grundsätzlich eine Indikation zur Cholezystektomie dar, um Komplikationen des Gallensteinleidens zu vermeiden. Bei der leichten und moderaten akuten Cholezystitis sollte auch bei älteren Patienten Cholezystektomie möglichst innerhalb von 24 Stunden nach der stationären Aufnahme erfolgen. Bei der simultanen Choledocho- und Cholezystolithiasis oder unkomplizierten biliären Pankreatitis sollte sie nach der endoskopischen retrograden Cholangiografie mit Steinextraktion noch innerhalb desselben stationären Aufenthalts durchgeführt werden. Das erhöhte Risiko, in der Folge der Cholelithiasis ein Gallenblasen- oder Gallenwegskarzinom zu entwickeln, steigt mit dem Alter an, sodass die Cholezystektomie auch karzinompräventiv ist.
Obere gastrointestinale Blutung mit hämorrhagischem Schock am Ende einer Urlaubsreise: Präklinische und innerklinische Versorgung eines gastrointestinalen Notfalls
Authors: Nguyen-Tat M. , Hoffman A. , Marquardt J. U. , Buggenhagen H. , Münzel T. , Kneist W. , Galle P. R. , Kiesslich R. , Rey J. W.
Published: July 2014

Nach der Rückkehr aus dem Urlaub wurde ein 55-jähriger Patient mit Teerstuhl und hämorrhagischem Schock im Zugabteil eines InterCity der Deutschen Bahn notfallmedizinisch versorgt und in ein Krankenhaus der Maximalversorgung eingeliefert. Hier erfolgte zunächst die weitere notfallmedizinische Behandlung, in deren Rahmen in der internistischen Notaufnahme in interdisziplinärer Zusammenarbeit eine Stabilisierung der Hämodynamik sowie die Sicherung der Atemwege und Atemfunktion erfolgten. Anschließend wurde eine Notfall-Endoskopie des oberen Gastrointestinaltrakts durchgeführt. Ursächlich für das hämorrhagische Schockgeschehen war eine arteriell spritzende, endoskopisch nicht zu stillende Blutung im Duodenum. Die definitive Blutungsstillung gelingt schließlich im Rahmen einer notfallmäßigen Laparatomie. Durch ein an die Versorgung traumatologischer Patienten angelehntes, aber für gastroenterologische Patienten mit Schockgeschehen nicht regelhaft vorhandenes Schockraum-Management konnte im vorliegenden Falle eines hochgradig instabilen Patienten durch die spontane Übernahme von etablierten Algorithmen aus der interdisziplinären Versorgung von Trauma-Patienten eine adäquate Kreislaufstabilisierung sowie Blutungskontrolle erreicht werden. Auch wenn ein Großteil der oberen gastrointestinalen Blutungen spontan sistieren, sollte wie für hier berichtete internistische Notfälle mit hämorrhagischem Schockgeschehen eine notfallmedizinische Versorgung nach Algorithmen entwickelt und implementiert werden. Am vorliegenden Fall wird ein mögliches beispielhaftes Vorgehen diskutiert sowie ein Vorschlag für ein mögliches Schockraum-Protokoll für diese Patientengruppe entwickelt.
Simulation of interplanetary magnetic field By penetration into the magnetotail
Authors: Guo Jiuling , Shen Chao , Liu Zhenxing
Published: July 2014

Based on our global 3D magnetospheric MHD simulation model, we investigate the phenomena and physical mechanism of the By component of the interplanetary magnetic field (IMF) penetrating into the magnetotail. We find that the dayside reconnected magnetic field lines move to the magnetotail, get added to the lobe fields, and are dragged in the IMF direction. However, the By component in the plasma sheet mainly originates from the tilt and relative slippage of the south and north lobes caused by plasma convection, which results in the original Bz component in the plasma sheet rotating into a By component. Our research also shows that the penetration effect of plasma sheet By from the IMF By during periods of northward IMF is larger than that during periods of southward IMF.
Peptide-induced membrane curvature in edge-stabilized open bilayers: A theoretical and molecular dynamics study
Authors: Pannuzzo Martina , Raudino Antonio , Böckmann Rainer A.
Published: July 2014

Peptide- or protein-induced curvatures of lipid membranes may be studied in molecular dynamics (MD) simulations. In these, membranes are usually modeled as infinitely extended bilayers by using periodic boundary conditions. However, the enforced periodicity results in an underestimation of the bending power of peptides, unless the patch size is much larger than the induced curvature radii. In this letter, we propose a novel approach to evaluate the bending power of a given distribution and/or density of peptides based on the use of flat open-edged lipid patches. To ensure long-lived metastable structures, the patch rim is stabilized in MD simulations by a local enrichment with short-chain lipids. By combining the theory of continuum elastic media with MD simulations, we prove that open-edged patches evolve from a planar state to a closed vesicle, with a transition rate that strongly depends on the concentration of lipid soluble peptides. For close-to-critical values for the patch size and edge energy, the response to even small changes in peptide concentration adopts a transition-like behavior (buckling instability). The usage of open-edged membrane patches amplifies the bending power of peptides, thereby enabling the analysis of the structural properties of membrane-peptide systems. We applied the presented method to investigate the curvature induced by aggregating β -amyloid peptides, unraveling a strong sensitivity of membrane deformation to the peptide concentration.
Thermal radiation of laser heated niobium clusters ${\rm Nb}_N^+$ Nb N+, 8 ⩽ N ⩽ 22
Authors: Hansen Klavs , Li Yejun , Kaydashev Vladimir , Janssens Ewald
Published: July 2014

The thermal radiation from small, laser heated, positively charged niobium clusters has been measured. The emitted power was determined by the quenching effect on the metastable decay, employing two different experimental protocols. The radiative power decreases slightly with cluster size and shows no strong size-to-size variations. The magnitude is 40–50 keV/s at the timescale of several microseconds, which is the measured crossover time from evaporative to radiative cooling.
Efficient algorithms for semiclassical instanton calculations based on discretized path integrals
Authors: Kawatsu Tsutomu , Miura Shinichi
Published: July 2014

Path integral instanton method is a promising way to calculate the tunneling splitting of energies for degenerated two state systems. In order to calculate the tunneling splitting, we need to take the zero temperature limit, or the limit of infinite imaginary time duration. In the method developed by Richardson and Althorpe [J. Chem. Phys. 134, 054109 (2011)], the limit is simply replaced by the sufficiently long imaginary time. In the present study, we have developed a new formula of the tunneling splitting based on the discretized path integrals to take the limit analytically. We have applied our new formula to model systems, and found that this approach can significantly reduce the computational cost and gain the numerical accuracy. We then developed the method combined with the electronic structure calculations to obtain the accurate interatomic potential on the fly. We present an application of our ab initio instanton method to the ammonia umbrella flip motion.
Theory of photoacoustic effect in media with thermal memory
Authors: Galović S. , Šoškić Z. , Popović M. , Čevizović D. , Stojanović Z.
Published: July 2014

This paper presents a model for indirect photoacoustic response that includes thermal memory effects. At low frequencies, the model reduces to the well-known thermal piston model of photoacoustic response given by Rosencweig and Gersho. However, at high frequencies, the presented model predicts resonant behavior of amplitudes and phases of photoacoustic response and determines the respective resonant frequencies. The results of the presented model enable experimental determination of standard thermal properties of solids (thermal diffusivity and thermal conductivity), as well as thermal memory properties, thermal relaxation time, and heat propagation speed.
Reversible amorphous-crystalline phase changes in a wide range of Se1−xTex alloys studied using ultrafast differential scanning calorimetry
Authors: Vermeulen Paul. A. , Momand Jamo , Kooi Bart J.
Published: July 2014

The reversible amorphous-crystalline phase change in a chalcogenide material, specifically the Se1−xTex alloy, has been investigated for the first time using ultrafast differential scanning calorimetry. Heating rates and cooling rates up to 5000 K/s were used. Repeated reversible amorphous-crystalline phase switching was achieved by consecutively melting, melt-quenching, and recrystallizing upon heating. Using a well-conditioned method, the composition of a single sample was allowed to shift slowly from 15 at. %Te to 60 at. %Te, eliminating sample-to-sample variability from the measurements. Using Energy Dispersive X-ray Spectroscopy composition analysis, the onset of melting for different Te-concentrations was confirmed to coincide with the literature solidus line, validating the use of the onset of melting Tm as a composition indicator. The glass transition Tg and crystallization temperature Tc could be determined accurately, allowing the construction of extended phase diagrams. It was found that Tm and Tg increase (but Tg/Tm decrease slightly) with increasing Te-concentration. Contrarily, the Tc decreases substantially, indicating that the amorphous phase becomes progressively unfavorable. This coincides well with the observation that the critical quench rate to prevent crystallization increases about three orders of magnitude with increasing Te concentration. Due to the employment of a large range of heating rates, non-Arrhenius behavior was detected, indicating that the undercooled liquid SeTe is a fragile liquid. The activation energy of crystallization was found to increase 0.5–0.6 eV when the Te concentration increases from 15 to 30 at. % Te, but it ceases to increase when approaching 50 at. % Te.
Enhanced phase sensitivity of metamaterial absorbers near the point of darkness
Authors: Vasić Borislav , Gajić Radoš
Published: July 2014

Plasmonic resonances are accompanied by abrupt phase changes. Utilization of this phase signal and lower phase noises can improve the refractive index resolution of plasmonic sensors. It is shown that the maximal phase change in the frequency domain is achieved at the point of the minimal reflection—the point of darkness. Since the metamaterial absorbers have near zero reflection at their resonance by definition, their phase can be used for sensing purpose. Considered metamaterial absorbers consist of parallel gold strips separated by a dielectric spacer from a thick metallic plate. By the optimization of the spacer thickness and strip widths, and by the adjustment of the angle of incidence, the phase sensitivity above 104 deg/RIU can be achieved in the dynamic range of 2×10−2 RIU.
Enhanced room-temperature mid-ultraviolet emission from AlGaN/AlN Stranski-Krastanov quantum dots
Authors: Himwas C. , den Hertog M. , Bellet-Amalric E. , Songmuang R. , Donatini F. , Si Dang Le , Monroy E.
Published: July 2014

We report on the identification of an optimum deposited amount of AlGaN in AlGaN/AlN quantum dot (QD) superlattices grown by molecular-beam epitaxy, which grants maximum luminescence at room temperature by finding a compromise between the designs providing maximum internal quantum efficiency (60%) and maximum QD density (9.0 × 1011 cm−2). The average Al composition in the QDs is estimated at 10.6% ± 0.8% by combining x-ray diffraction measurements with three-dimensional calculations of the strain distribution. The effect of the variation of the QD height/base-diameter ratio on the interband and intraband optical properties was explored by fitting the experimental data with three-dimensional calculations of the band diagram and quantum confined states.
Sheath-induced distortions in particle distributions near enhanced polar outflow probe particle sensors
Authors: Hussain S. , Marchand R.
Published: July 2014

We discuss sheath and kinetic effects on ion and electron distribution functions at the aperture of enhanced Polar Outflow Probe particle sensors. For this purpose, the interaction between the CASSIOPE spacecraft and space environment is simulated fully kinetically using the electrostatic Particle In Cell code PTetra. The simulations account for the geometry of the main features of the spacecraft body, the booms, and the sensors. In addition to the background plasma, the model also accounts for Earth magnetic field. The plasma parameters assumed in the simulations are obtained from the latest version of the International Reference Ionosphere (IRI) model and the value of magnetic field is obtained from the International Geophysical Reference Field model. Our analysis shows significant distortions in the ion distribution function in the plane of the sensor aperture, as well as in the direction along the boom holding the sensor. We argue that significant distortions and asymmetries should also occur at the aperture of the suprathermal electron imager when suprathermal electrons are detected, with energies of 5 eV or more.
Large field-induced magnetocaloric effect and magnetoresistance in ErNiSi
Authors: Gupta Sachin , Rawat R. , Suresh K. G.
Published: July 2014

Large magnetocaloric effect (MCE) and magnetoresistance (MR) together with negligible hysteresis loss have been observed in ErNiSi compound, which undergoes metamagnetic transition at low temperatures. Magnetization, heat capacity, and resistivity measurements confirm the metamagnetic transition. Both MCE and MR follow H2 dependence in the paramagnetic regime. The maximum value of isothermal entropy change (ΔSM) and MR for a field change of 50 kOe are found to be 19.1 J/kg K and ∼34%, respectively. Large MCE with negligible magnetic hysteresis loss could make this material promising for low temperature magnetic refrigeration.
Fission signal detection using helium-4 gas fast neutron scintillation detectors
Authors: Lewis J. M. , Kelley R. P. , Murer D. , Jordan K. A.
Published: July 2014

We demonstrate the unambiguous detection of the fission neutron signal produced in natural uranium during active neutron interrogation using a deuterium-deuterium fusion neutron generator and a high pressure 4He gas fast neutron scintillation detector. The energy deposition by individual neutrons is quantified, and energy discrimination is used to differentiate the induced fission neutrons from the mono-energetic interrogation neutrons. The detector can discriminate between different incident neutron energies using pulse height discrimination of the slow scintillation component of the elastic scattering interaction between a neutron and the 4He atom. Energy histograms resulting from this data show the buildup of a detected fission neutron signal at higher energies. The detector is shown here to detect a unique fission neutron signal from a natural uranium sample during active interrogation with a (d, d) neutron generator. This signal path has a direct application to the detection of shielded nuclear material in cargo and air containers. It allows for continuous interrogation and detection while greatly minimizing the potential for false alarms.
Opto-mechano-fluidic viscometer
Authors: Han Kewen , Zhu Kaiyuan , Bahl Gaurav
Published: July 2014

The recent development of opto-mechano-fluidic resonators has provided—by harnessing photon radiation pressure—a microfluidics platform for the optical sensing of fluid density and bulk modulus. Here, we show that fluid viscosity can also be determined through optomechanical measurement of the vibrational noise spectrum of the resonator mechanical modes. A linear relationship between the spectral linewidth and root-viscosity is predicted and experimentally verified in the low viscosity regime. Our result is a step towards multi-frequency measurement of viscoelasticity of arbitrary fluids, without sample contamination, using highly sensitive optomechanics techniques.
GaN-based vertical-cavity laser performance improvements using tunnel-junction-cascaded active regions
Authors: Piprek Joachim
Published: July 2014

This Letter investigates the output power enhancement achieved by tunnel junction insertion into the InGaN multi-quantum well (MQW) active region of a 410 nm vertical-cavity surface-emitting laser which enables the repeated use of carriers for light generation (carrier recycling). While the number of quantum wells remains unchanged, the tunnel junction eliminates absorption caused by the non-uniform MQW carrier distribution. The thermal resistance drops and the excess bias lead to a surprisingly small rise in self-heating.
Nonlinear magnetoelectric effect in PZT/Terfenol-D nanobilayer on a substrate with surface stress
Authors: Shi Yang , Niu Longfei , Gao Yuanwen
Published: July 2014

Based on a linear piezoelectric constitutive relation and a nonlinear magnetostrictive constitutive relation, a nonlinear magnetoelectric (ME) effect model for lead zirconate titanate (PZT)/Terfenol-D nanobilayer on a substrate has been developed. In this study, the nonlinear ME coefficients at bending mode for two cases (without surface stress and with surface stress) are calculated by using Gurtin-Murdoch theory. The difference between two cases and the influence of residual surface tension are discussed. At the same time, the clamping effect of the substrate on ME effect is studied by altering the thickness ratio of the substrate and selecting different substrate materials. The influences of frequency of the magnetic field, PZT volume fraction on the ME effect are investigated, respectively. Finally, the dependence of ME effect on pre-stress is presented. The results show that for the nanobilayer, both the residual surface tension and surface stress have non-ignored effects on the ME effect. Besides, the resonant frequency of the nanobilayer is very low at the bending mode, which can be enhanced by increasing the thickness ratio of the substrate. Also, the substrate can weaken the ME effect due to the clamping effect, and a more soft substrate material should be selected for large ME effect. In addition, pre-stress plays an important role in the nonlinear ME coupling effect of the model developed.