Self-assembly of Chloro-Bridged Arene-Ruthenium Based Rectangle: Synthesis, Structural Characterization and Sensing Study

Self-assembly of a chloro-bridged half-sandwich p-cymene ruthenium(II) complex Ru-2(mu-Cl-2)(eta(6)-p-cymene)(2)Cl-2] 1 with linear ditopic donor L; trans-1,2-bis(4-pyridyl) ethylene] in presence of 2 eq. AgNO3 in CH3CN yielded a chloro-bridged molecular rectangle 2. The rectangle 2 was isolated as nitrate salt in high yield (90 %) and characterized by infra-red, H-1 NMR spectroscopy including ESI-MS analyses. Molecular structure of 2 was determined by single crystal X-ray diffraction study The diffraction analysis shows that 2 adopts a tetranuclear rectangular geometry with the dimensions of 5.51 angstrom x 13.29 angstrom and forming an infinite supramolecular chain with large internal porosity arising through multiple pi-pi and CH-pi interactions between the adjacent rectangles. Furthermore, rectangle 2 is used as selective receptor for phenolic-nitroaromatic compounds such as picric acid, dinitrophenol and nitrophenol.

Self-Assembled Discrete Molecules for Sensing Nitroaromatics

Efficient sensing of trace amount nitroaromatic (NAC) explosives has become a major research focus in recent time due to concerns over national security as well as their role as environment pollutants. NO2-containing electron-deficient aromatic compounds, such as picric acid (PA), trinitrotoluene (TNT), and dinitrotoluene (DNT), are the common constituents of many commercially available chemical explosives. In this article, we have summarized our recent developments on the rational design of electron-rich self-assembled discrete molecular sensors and their efficacy in sensing nitroaromatics both in solution as well as in vapor phase. Several p-electron-rich fluorescent metallacycles (squares, rectangles, and tweezers/pincers) and metallacages (trigonal and tetragonal prisms) have been synthesized by means of metal-ligand coordination-bonding interactions, with enough internal space to accommodate electron-deficient nitroaromatics at the molecular level by multiple supramolecular interactions. Such interactions subsequently result in the detectable fluorescence quenching of sensors even in the presence of trace quantities of nitroaromatics. The fascinating sensing characteristics of molecular architectures discussed in this article may enable future development of improved sensors for nitroaromatic explosives.

Experimental determination and theoretical correlation for the solubilities of dicarboxylic acid esters in supercritical carbon dioxide

The synthesis of high molecular weight esters such as bis (2-ethylhexyl) sebacate is of significance for its use as a lubricant. This ester is synthesized by the transesterification of dimethyl sebacate with 2-ethylhexanol. Therefore, the solubilities of bis (2-ethylhexyl) sebacate and dimethyl sebacate were determined at 308-328 K at pressures of 10-18 MPa in supercritical carbon dioxide. The solubility of dimethyl sebacate was always higher than bis (2-ethylhexyl) sebacate at a given temperature and pressure. The Mendez-Teja model was used to verify the self-consistency of data. Further, a new semi-empirical model with three parameters was developed using the solution theory coupled with Wilson activity coefficient. This model was used to correlate the experimental data of this work and solubilities of many high molecular weight esters reported in the literature. (C) 2015 Elsevier B.V. All rights reserved.

Autonomous Star Camera Calibration and Spacecraft Attitude Determination

This paper presents two methods of star camera calibration to determine camera calibrating parameters (like principal point, focal length etc) along with lens distortions (radial and decentering). First method works autonomously utilizing star coordinates in three consecutive image frames thus independent of star identification or biased attitude information. The parameters obtained in autonomous self-calibration technique helps to identify the imaged stars with the cataloged stars. Least Square based second method utilizes inertial star coordinates to determine satellite attitude and star camera parameters with lens radial distortion, both independent of each other. Camera parameters determined by the second method are more accurate than the first method of camera self calibration. Moreover, unlike most of the attitude determination algorithms where attitude of the satellite depend on the camera calibrating parameters, the second method has the advantage of computing spacecraft attitude independent of camera calibrating parameters except lens distortions (radial). Finally Kalman filter based sequential estimation scheme is employed to filter out the noise of the LS based estimation.

Reconstruction of the Disassembly Pathway of an Icosahedral Viral Capsid and Shape Determination of Two Successive Intermediates

Viral capsids derived from an icosahedral plant virus widely used in physical and nanotechnological investigations were fully dissociated into dimers by a rapid change of pH. The process was probed in vitro at high spatiotemporal resolution by time-resolved small-angle X-ray scattering using a high brilliance synchrotron source. A powerful custom-made global fitting algorithm allowed us to reconstruct the most likely pathway parametrized by a set of stoichiometric coefficients and to determine the shape of two successive intermediates by ab initio calculations. None of these two unexpected intermediates was previously identified in self-assembly experiments, which suggests that the disassembly pathway is not a mirror image of the assembly pathway. These findings shed new light on the mechanisms and the reversibility of the assembly/disassembly of natural and synthetic virus-based systems. They also demonstrate that both the structure and dynamics of an increasing number of intermediate species become accessible to experiments.

Does Immigration Raise Natives’ Income? National and Regional Evidence from Spain

How immigration affects the labor market of the host country is a topic of major concern for many immigrant-receiving nations. Spain is no exception following the rapid increase in immigrant flows experienced over the past decade. We assess the impact of immigration on Spanish natives’ income by estimating the net immigration surplus accruing at the national level and at high immigrant-receiving regions while taking into account the imperfect substitutability of immigrant and native labor. Specifically, using information on the occupational densities of immigrants and natives of different skill levels, we develop a mapping of immigrant-to-native self-reported skills that reveals the combination of natives across skills that would be equivalent to an immigrant of a given self-reported skill level, which we use to account for any differences between immigrant self-reported skill levels and their effective skills according to the Spanish labor market. We find that the immigrant surplus amounts to 0.04 percent of GDP at the national level and it is even higher for some of the main immigrant-receiving regions, such as Cataluña, Valencia, Madrid, and Murcia.

Precision of age determination of northern offshore spotted dolphins.

We investigated within- and between-reader precision in estimating age for northern offshore spotted dolphins and possible effects on precision from the sex and age-class of specimens. Age was estimated from patterns of growth layer groups i n the dentine and cementum of the dolphins' teeth. Each specimen was aged at least three times by each of two persons. Two data samples were studied. The first comprised 800 of each sex from animals collected during 1973-78. The second included 45 females collected during 1981. There were significant, generally downward trends through time in the estimates from multiple readings of the 1973-78 data. These trends were slight, and age distributions from last readings and mean estimates per specimen appeared to be homogeneous. The largest factor affecting precision in the 1973-78 data set was between-reader variation. In light of the relatively high within-reader precision (trends considered), the consistent between-reader differences suggest a problem of accuracy rather than precision for this series. Within-reader coefficients of variation averaged approximately 7% and 11%. Pooling the data resulted i n an average coefficient of variation near 16%. Within- and between-reader precision were higher for the 1981 sample, and the data homogeneous over both factors. CVs averaged near 5% and 6% for the two readers. These results point to further refinements in reading the 1981 series. Properties of the 1981 sample may be partly responsible for greater precision: by chance there were proportionately fewer older dolphins included, and preparation and selection criteria were probably more stringent. (PDF contains 35 pages.)

Age determination methods for northwest Atlantic species

The successful application of techniques to enhance detection of age marks in biological specimens is of vital importance in fisheries research. This manual documents age determination techniques used by staff at the Woods Hole Laboratory, National Marine Fisheries Service. General information on procedures for preparing anatomical structures is described, together with criteria used to interpret growth patterns and assign ages. Annotated photographs of age structures are provided to illustrate criteria. Detailed procedures are given for the following species: Atlantic herring (Clupea harengus), haddock (Melanogrammus aeglefinus), Atlantic cod (Gadus morhua), pollock (Pollachius virens), silver hake (Merluccius bilinearis), red hake (Urophycis chuss), black sea bass (Centropristis striata), weakfish (Cynoscion regalis), Atlantic mackerel (Scomber scombrus), butterfish (Peprilus triacanthus), redfish (Sebastes fasciatus), summer flounder (Paralichthys dentatus), winter flounder (Pseudopleuronectes americanus), witch flounder (Glyptocephalus cynoglossus), American plaice (Hippoglossoides platessoides), yellowtail flounder (Limanda ferruginea), surf clam (Spisula solidissima), and ocean quahog (Arctica islandica). (PDF file contains 142 pages.)

Proceedings of the International Workshop on age determination of oceanic pelagic fishes: Tunas, billfishes, and sharks, Miami, Florida, February 15-18,1982

Accurate and precise estimates of age and growth rates are essential parameters in understanding the population dynamics of fishes. Some of the more sophisticated stock assessment models, such as virtual population analysis, require age and growth information to partition catch data by age. Stock assessment efforts by regulatory agencies are usually directed at specific fisheries which are being heavily exploited and are suspected of being overfished. Interest in stock assessment of some of the oceanic pelagic fishes (tunas, billfishes, and sharks) has developed only over the last decade, during which exploitation has increased steadily in response to increases in worldwide demand for these resources. Traditionally, estimating the age of fishes has been done by enumerating growth bands on skeletal hardparts, through length frequency analysis, tag and recapture studies, and raising fish in enclosures. However, problems related to determining the age of some of the oceanic pelagic fishes are unique compared with other species. For example, sampling is difficult for these large, highly mobile fishes because of their size, extensive distributions throughout the world's oceans, and for some, such as the marlins, infrequent catches. In addition, movements of oceanic pelagic fishes often transect temperate as well as tropical oceans, making interpretation of growth bands on skeletal hardparts more difficult than with more sedentary temperate species. Many oceanic pelagics are also long-lived, attaining ages in excess of 30 yr, and more often than not, their life cycles do not lend themselves easily to artificial propagation and culture. These factors contribute to the difficulty of determining ages and are generally characteristic of this group-the tunas, billfishes, and sharks. Accordingly, the rapidly growing international concern in managing oceanic pelagic fishes, as well as unique difficulties in ageing these species, prompted us to hold this workshop. Our two major objectives for this workshop are to: I) Encourage the interchange of ideas on this subject, and 2) establish the "state of the art." A total of 65 scientists from 10 states in the continental United States and Hawaii, three provinces in Canada, France, Republic of Senegal, Spain, Mexico, Ivory Coast, and New South Wales (Australia) attended the workshop held at the Southeast Fisheries Center, Miami, Fla., 15-18 February 1982. Our first objective, encouraging the interchange of ideas, is well illustrated in the summaries of the Round Table Discussions and in the Glossary, which defines terms used in this volume. The majority of the workshop participants agreed that the lack of validation of age estimates and the means to accomplish the same are serious problems preventing advancements in assessing the age and growth of fishes, particularly oceanic pelagics. The alternatives relating to the validation problem were exhaustively reviewed during the Round Table Discussions and are a major highlight of this workshop. How well we accomplished our second objective, to establish the "state of the art" on age determination of oceanic pelagic fishes, will probably best be judged on the basis of these proceedings and whether future research efforts are directed at the problem areas we have identified. In order to produce high-quality papers, workshop participants served as referees for the manuscripts published in this volume. Several papers given orally at the workshop, and included in these proceedings, were summarized from full-length manuscripts, which have been submitted to or published in other scientific outlets-these papers are designated as SUMMARY PAPERS. In addition, the SUMMARY PAPER designation was also assigned to workshop papers that represented very preliminary or initial stages of research, cursory progress reports, papers that were data shy, or provide only brief reviews on general topics. Bilingual abstracts were included for all papers that required translation. We gratefully acknowledge the support of everyone involved in this workshop. Funding was provided by the Southeast Fisheries Center, and Jack C. Javech did the scientific illustrations appearing on the cover, between major sections, and in the Glossary. (PDF file contains 228 pages.)

Integrated Sensor Systems for Vessels of Opportunity, National Oceanographic Centre, Southampton, UK, October 10-12,2006 : workshop proceedings

The use of self-contained, low-maintenance sensor systems installed on commercial vessels is becoming an important monitoring and scientific tool in many regions around the world. These systems integrate data from meteorological and water quality sensors with GPS data into a data stream that is automatically transferred from ship to shore. To begin linking some of this developing expertise, the Alliance for Coastal Technologies (ACT) and the European Coastal and Ocean Observing Technology (ECOOT) organized a workshop on this topic in Southampton, United Kingdom, October 10-12, 2006. The participants included technology users, technology developers, and shipping representatives. They collaborated to identify sensors currently employed on integrated systems, users of this data, limitations associated with these systems, and ways to overcome these limitations. The group also identified additional technologies that could be employed on future systems and examined whether standard architectures and data protocols for integrated systems should be established. Participants at the workshop defined 17 different parameters currently being measured by integrated systems. They identified that diverse user groups utilize information from these systems from resource management agencies, such as the Environmental Protection Agency (EPA), to local tourism groups and educational organizations. Among the limitations identified were instrument compatibility and interoperability, data quality control and quality assurance, and sensor calibration andlor maintenance frequency. Standardization of these integrated systems was viewed to be both advantageous and disadvantageous; while participants believed that standardization could be beneficial on many levels, they also felt that users may be hesitant to purchase a suite of instruments from a single manufacturer; and that a "plug and play" system including sensors from multiple manufactures may be difficult to achieve. A priority recommendation and conclusion for the general integrated sensor system community was to provide vessel operators with real-time access to relevant data (e.g., ambient temperature and salinity to increase efficiency of water treatment systems and meteorological data for increased vessel safety and operating efficiency) for broader system value. Simplified data displays are also required for education and public outreach/awareness. Other key recommendations were to encourage the use of integrated sensor packages within observing systems such as 100s and EuroGOOS, identify additional customers of sensor system data, and publish results of previous work in peer-reviewed journals to increase agency and scientific awareness and confidence in the technology. Priority recommendations and conclusions for ACT entailed highlighting the value of integrated sensor systems for vessels of opportunity through articles in the popular press, and marine science. [PDF contains 28 pages]

Self-induced transmission on intersubband resonance in multiple quantum wells

We investigate the nonlinear propagation of ultrashort pulses on resonant intersubband transitions in multiple semiconductor quantum wells. It is shown that the nonlinearity rooted from electron-electron interactions destroys the condition giving rise to self-induced transparency. However, by adjusting the area of input pulse, we find the signatures of self-induced transmission due to a full Rabi flopping of the electron density, and this phenomenon can be approximately interpreted by the traditional standard area theorem via defining the effective area of input pulse.

Spatiotemporal evolution and multiple self-focusing of ultrashort pulses in a resonant two-level medium

The spatiotemporal evolutions of ultrashort pulses in two dimensions are investigated numerically by solving the coupled Maxwell-Bloch equations without invoking the slowly varying envelope approximation and rotating-wave approximation. For an on-axis 2n pi sech pulse, local delay makes the temporal split 2 pi sech pulses crescent-shaped in the transverse distribution. Due to the transverse effect, the temporal split 2 pi sech pulses become unstable and experience reshaping during the propagation process. Then, interference occurs between the successive crescent-shaped pulses and multiple self-focusing can form.

Intense laser beam guiding in self-induced electron cavitation channel in underdense plasmas

In underdense plasmas, the transverse ponderomotive force of an intense laser beam with Gaussian transverse profile expels electrons radially, and it can lead to an electron cavitation. An improved cavitation model with charge conservation constraint is applied to the determination of the width of the electron cavity. The envelope equation for laser spot size derived by using source-dependent expansion method is extended to including the electron cavity. The condition for self-guiding is given and illuminated by an effective potential for the laser spot size. The effects of the laser power, plasma density and energy dissipation on the self-guiding condition are discussed.