An eleven-vertex deltahedron with hexacapped trigonal bipyramidal geometry.

International audienceThe first elemental cluster with hexacapped trigonal bipyramidal geometry is revealed in the luminescent undecanuclear silver complex which is stabilized by nine dithiocarbamate ligands and has an interstitial hydride. The hydride position within the Ag(11) cage is confirmed by a DFT investigation

Targeting F-Box Protein Fbxo3 Attenuates Lung Injury Induced by Ischemia-Reperfusion in Rats

Background: Increasing evidence suggests that Fbxo3 signaling has an important impact on the pathophysiology of the inflammatory process. Fbxo3 protein inhibition has reduced cytokine-driven inflammation and improved disease severity in animal model of Pseudomonas-induced lung injury. However, it remains unclear whether inhibition of Fbxo3 protein provides protection in acute lung injury induced by ischemia-reperfusion (I/R). In this study, we investigated the protective effects of BC-1215 administration, a Fbxo3 inhibitor, on acute lung injury induced by I/R in rats.Methods: Lung I/R injury was induced by ischemia (40 min) followed by reperfusion (60 min). The rats were randomly assigned into one of six experimental groups (n = 6 rats/group): the control group, control + BC-1215 (Fbxo3 inhibitor, 0.5 mg/kg) group, I/R group, or I/R + BC-1215 (0.1, 0.25, 0.5 mg/kg) groups. The effects of BC-1215 on human alveolar epithelial cells subjected to hypoxia-reoxygenation (H/R) were also examined.Results: BC-1215 significantly attenuated I/R-induced lung edema, indicated by a reduced vascular filtration coefficient, wet/dry weight ratio, lung injury scores, and protein levels in bronchoalveolar lavage fluid (BALF). Oxidative stress and the level of inflammatory cytokines in BALF were also significantly reduced following administration of BC-1215. Additionally, BC-1215 mitigated I/R-stimulated apoptosis, NF-κB, and mitogen-activated protein kinase activation in the injured lung tissue. BC-1215 increased Fbxl2 protein expression and suppressed Fbxo3 and TNFR associated factor (TRAF)1–6 protein expression. BC-1215 also inhibited IL-8 production and NF-κB activation in vitro in experiments with alveolar epithelial cells exposed to H/R.Conclusions: Our findings demonstrated that Fbxo3 inhibition may represent a novel therapeutic approach for I/R-induced lung injury, with beneficial effects due to destabilizing TRAF proteins

Dynamic relationships between S&P 500 stock index and volatility index

[[abstract]]本研究探討S&P500 股價指數與波動率指數之間的關係，實證結果顯示S &P500 股價指數與波動率指數通常具有負向關係，但有些時候波動率指 數會與其標的股價指數呈現正向關係變動， 處於波動率高的期間， 投資 者的不安情緒增高， 股票市場及波動率指數的波動變得更劇烈， 動態相 關性也會變得較弱，且波動率指數與S&P 500 股價指數呈現正相關的頻 率會增加。[[abstract]]This study examines the relationships between S&P 500 stock index and volatility index. The results indicate that the relationships between S&P 500 stock index and volatility index is usually negative. But sometimes volatility index does not move opposite its underlying index. During the high volatility period, the investor fear is greater. The stock market and volatility index are more volatile, the dynamic correlation between S&P 500 stock index and volatility index becomes weaker. And volatility index moves in the same direction with S&P 500 stock index more often

A Cover-Up Scheme for Data-Centric Storage in Wireless Sensor Networks

[[abstract]]One critical problem in wireless sensor networks is how to make the effective use of the vast amount of data by providing sensor and sink nodes with efficient data storing and retrieving, respectively. Several data-centric storage techniques had been proposed to exploit data storing and retrieving, but all of them failed to effectively deal with hotspot storage due to irregular sensor deployments or data distribution. In this paper, we propose a cover-up scheme for data-centric storage in wireless sensor networks. In our scheme, the storage node generates a virtual coordinate to feign that it is far away from the hash location. A geographic routing protocol forwarding an event data to a storage node will ignore the original storage node and find a new storage node whose coordinate is the closest to the hash location. Our cover-up mechanism can adjust to another storage node dynamically when a storage node is full. Simulations have shown that our cover-up scheme can reduce the energy consumption and achieve better quality of data.[[notice]]補正完畢[[journaltype]]國內[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[countrycodes]]TW

Multi-channel medium access control protocol with channel distribution for mobile ad hoc networks

[[abstract]]This study proposes a novel multi-channel medium access control protocol for mobile ad hoc networks that enables nodes to transmit packets in distributed channels. In our protocol, the ad hoc traffic indication message window is divided into two windows. The first window is called the deciding channel window (DCW). Source and destination nodes can negotiate with each other in deciding a channel that can be used to compete for the final data channel in the DCW. The second window is called the exchanging packet window (EPW). Pair source and destination nodes can compete to obtain a channel to transfer packets in the EPW. This mechanism can distribute pair source and destination nodes to compete for a data channel. Hence, because of this, collisions can be avoided greatly and throughput can be increased. The simulation results show that our protocol successfully exploits the use of the bandwidth of multiple channels effectively.[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙

A TDMA-based Bandwidth Reservation Protocol for QoS Routing in a Wireless Mobile Ad Hoc Network

This paper considers the bandwidth reservation problem in a mobile ad hoc network (MANET) to support QoS (quality-of-service) routing. We approach this problem by assuming a common channel shared by all hosts under a TDMA (Time Division Multiple Access) channel model. Existing solutions have addressed this problem by assuming a stronger multi-antenna model [3], [6], where the bandwidth of a link is independent of the transmitting/receiving activities of its neighboring links, or a less stronger CDMA-over-TDMA channel model [7], where the use of a time slot on a link is only dependent of the status of its one-hop neighboring links. While more practical and less costly, using a TDMA model needs to face the challenge of radio interference problems. In this paper, we propose a new protocol that can reserve routes by addressing both the hidden-terminal and exposed-terminal problems. The protocol can conduct accurate bandwidth calculation while performing route discovery. Simulation results are presented to verify how this new protocol performs

A Nanospheric Polyhydrido Copper Cluster of Elongated Triangular Orthobicupola Array: Liberate H2 from Solar Energy

International audienceAn unprecedented air-stable, nanospheric polyhydrido copper cluster, [Cu20H11(S2P(OiPr)2)9] (1H), which is the first example of an elongated triangular orthobicupola array of Cu atoms having C3h symmetry, was synthesized and characterized. Its composition was primarily determined by electrospray ionization mass spectrometry, and it was fully characterized by 1H, 2H, and 31P NMR spectroscopy and single-crystal X-ray diffraction (XRD). The structure of complex 1H can be expressed in terms of a trigonal-bipyramidal [Cu2H5]3- unit anchored within an elongated triangular orthobicupola containing 18 Cu atoms, which is further stabilized by 18 S atoms from nine dithiophosphate ligands and six capping hydrides. The positions of the 11 hydrides revealed by low temperature XRD were supported by a density functional theory investigation on the simplified model [Cu20H11(S2PH2)9] with C3h symmetry. 1H is capable of releasing H2 gas upon irradiation with sunlight, under mild thermal conditions (65 °C), or in the presence of acids at room temperature

Crystal Structure, Photophysical Properties, and Theoretical Investigation of Extremely Distorted Pentacapped Trigonal-Prismatic Undecasilver Clusters

International audienceA new cluster family of the type [Ag11(S){S2P(OR)2}8]+ (R = Et, Pr, iPr) has been synthesized and characterized as their hexafluorophosphate salts. These compounds are the first silver dithiophosph(in)ato complexes exhibiting photoluminescence at ambient temperature. Their unprecedented skeletal structure describes a very distorted pentacapped trigonal-prismatic polyhedron. Geometry optimizations by DFT calculations on the R = H model reproduce the same structural arrangement in the ground state. Its electronic structure exhibits a low-lying LUMO with a large Ag(5s/5p) character whereas the highest occupied levels have a major contribution from the ligand sulfur lone pairs. The above-mentioned orbitals are shown to be responsible for the optical absorption and emission properties of these compounds

Octanuclear copper(I) clusters inscribed in a Se(12) icosahedron: anion-induced modulation of the core size and symmetry.

International audienceSynthesis and structural characterization of an octanuclear Cu(I) cluster [Cu(8){Se(2)P(O(i)Pr)(2)}(6)](PF(6))(2) (1) with an empty Cu(8) cubic core involving diisopropyl diselenophosphate (dsep) ligand has been demonstrated despite its high tendency to abstract anions even from the traces of impurities in the solvent. Reaction of 1 with anion sources (Bu(4)NF for F(-); NaBH(4) for H(-), and NaSH for S(2-)) in a 1:1 ratio produced anion-centered Cu(8) clusters with a formula [Cu(8)(X){Se(2)P(O(i)Pr)(2)}(6)](PF(6)) (X = F, 2a; H, 3a; D, 3a') and [Cu(8)(S){Se(2)P(O(i)Pr)(2)}(6)] (4) in high yields. In addition, fluoride- and hydride-centered Cu(8)(I) clusters [Cu(8)(X){Se(2)P(OEt)(2)}(6)](PF(6)) (X = F, 2b; H, 3b) could be generated in approximately 80% yield by direct reaction of [Cu(CH(3)CN)(4)](PF(6)), NH(4)Se(2)P(OEt)(2), and the anion sources (Bu(4)NF for F(-); NaBH(4) for H(-)) in 8:6:1 ratio. Whereas the structural elucidation of complexes 2 and 4 revealed an anion-centered cubic Cu(8) core surrounded by six dsep ligands, it was a tetracapped tetrahedral copper framework with a hydride in the center in compounds 3. All Cu...Cu distances along either the edge of the cube in 2 and 4 or the tetracapped tetrahedron in 3 are shorter than those identified in 1. Although the cubic (or spherical) contraction of the copper framework that was identified in a series of closed-shell anion-centered (except a hydride) Cu(8) cube having T(h) symmetry could be explained by the existence of strong anion-cation attractions, it was definitely a surprise that the hydride, which is the smallest closed-shell anion and spherical too, induced a tetrahedral contraction of four out of the eight Cu atoms in the empty cube 1, resulting in a tetracapped-tetrahedral geometry and reducing the symmetry to T from T(h). Furthermore the fact that the encapsulated anion induced modulation of the copper core size and symmetry was fully reproduced by DFT calculations on model compounds. To the best of our knowledge, this demonstrated the first example of the reduction of molecular symmetry (from T(h) to T) simply by changing the encapsulated species without altering the general bonding pattern of the surrounding ligands. We also demonstrated that the hydride can easily replace other anions (Cl(-), Br(-), F(-), S(2-), Se(2-)) in a very facile manner to produce hydride-centered species. Eventually, compounds 3 were stable in the presence of other anions, and hydride/deuteride exchange could not be achieved