2,560 research outputs found
Cleavage of GeâS and CâH bonds in the reaction of electron-deficient [Osâ(CO)â(ÎŒ-H)(ÎŒâ-PhâPCHâP(Ph)CâHâ)] with PhâGeSPh: Generation of thiophenol derivatives [Osâ(CO)â(ÎŒ-H)(ÎŒ-SPh)(ÎŒ-dppm)] and [Osâ(CO)â(ÎŒ-H)(ÎŒ-SPh)(ÎŒâ-SCâHâ)(ÎŒ-dppm)]
Heating the electron-deficient [Osâ(CO)â(ÎŒ-H)(ÎŒâ-PhâPCHâP(Ph)CâHâ)] (1) and PhâGeSPh in benzene at 80 °C led to the thiolato bridged compounds, [Osâ(CO)â(ÎŒ-H)(ÎŒ-SPh)(ÎŒ-dppm)] (2) and [Osâ(CO)â(ÎŒ-H)(ÎŒ-SPh)(ÎŒâ-SCâHâ)(ÎŒ-dppm)] (3), formed by cleavage of GeâS and CâS bonds of the ligand, in 40% and 17% yields, respectively. Both compounds 2 and 3 have been characterized by a combination of elemental analysis, infrared and ÂčH NMR spectroscopic data together with single crystal X-ray crystallography. Compound 3 contains an open triangle of osmium atoms bridged by a SPh and SCâHâ ligands on opposite sides of the cluster with a dppm ligand bridging one of the OsâOs edges. Compound 2 consists of a closed triangular cluster of osmium atoms with a bridging SPh, and a bridging hydride ligand on the same OsâOs edge, and a dppm ligand bridging one of the remaining OsâOs edges
Population inference of spin-induced quadrupole moments as a probe for non-black hole compact binaries
Gravitational-wave (GW) measurements of physical effects such as spin-induced
quadrupole moments can distinguish binaries consisting of black holes from
non-black hole binaries. While these effects may be poorly constrained for
single-event inferences with the second-generation detectors, combining
information from multiple detections can help uncover features of non-black
hole binaries. The spin-induced quadrupole moment has specific predictions for
different types of compact objects, and a generalized formalism must consider a
population where different types of compact objects co-exist. In this study, we
introduce a hierarchical mixture-likelihood formalism to estimate the {\it
fraction of non-binary black holes in the population}. We demonstrate the
applicability of this method using simulated GW signals injected into Gaussian
noise following the design sensitivities of the Advanced LIGO Advanced Virgo
detectors. We compare the performance of this method with a
traditionally-followed hierarchical inference approach. Both the methods are
equally effective to hint at inhomogeneous populations, however, we find the
mixture-likelihood approach to be more natural for mixture populations
comprising compact objects of diverse classes. We also discuss the possible
systematics in the mixture-likelihood approach, caused by several reasons,
including the limited sensitivity of the second-generation detectors, specific
features of the astrophysical population distributions, and the limitations
posed by the waveform models employed. Finally, we apply this method to the
LIGO-Virgo detections published in the second GW transient catalog (GWTC-2) and
find them consistent with a binary black hole population within the statistical
precision.Comment: 13 pages, 6 figures, 1 tabl
Profile of Neonatal Septicaemia at a District-level Sick Newborn Care Unit
Although sepsis is a major cause of morbidity and mortality among newborns in resource-poor countries, little data are available from rural areas on culture-proven sepsis. The aim of the present study was to provide information in this regard. The study reports results on the incidence and aetiology of neonatal sepsis cases admitted to a facility in a rural area in eastern India. Blood culture was done for all babies, with suspected clinical sepsis, who were admitted to the sick newborn care unit at Suri where the study was conducted during March 2009âAugust 2010. A standard form was used for collecting clinical and demographic data. In total, 216 neonatal blood culture samples were processed, of which 100 (46.3%) grew potential pathogens. Gram-negative infection was predominant (58/100 cases) mainly caused by enteric Gram-negative bacteria. Klebsiella pneumoniae was the most common Gram-negative isolate. The emergence of fungal infection was observed, with 40% of the infection caused by yeast. Gram-negative organisms exhibited 100% resistance to ampicillin, cefotaxime, and gentamicin. Amikacin and co-trimoxazole showed 95% (n=57) resistance, and ciprofloxacin showed 83.3% (n=50) resistance among the Gram-negative bacteria. Carbapenem showed emerging resistance (n=4; 6.6%). Results of analysis of risk factors showed an extremely significant association between gestation and sepsis and gender and sepsis. Gastrointestinal symptoms were highly specific for fungal infections. One-third of babies (n=29), who developed culture-positive sepsis, died. Blood culture is an investigation which is frequently unavailable in rural India. As a result, empirical antibiotic therapy is commonly used. The present study attempted to provide data for evidence-based antibiotic therapy given to sick newborns in such rural units. The results suggest that there is a high rate of antibiotic resistance in rural India. Urgent steps need to be taken to combat this resistance
Search for merger ejecta emission from late time radio observations of short GRBs using GMRT
Short gamma-ray bursts (GRBs) are the aftermath of compact binary mergers
involving neutron stars. If the merger remnant is a millisecond magnetar
instead of a black hole, a significant proportion of the rotational energy
deposited to the emerging ejecta can produce a late-time radio brightening from
its interaction with the ambient medium. Detection of this late-time radio
emission from short GRBs can have profound implications for understanding the
physics of the progenitor. We report the radio observations of five short GRBs
- 050709, 061210, 100625A, 140903A, and 160821B using the Giant Metrewave Radio
Telescope (GMRT) at 1250, 610, and 325 MHz frequencies after
years from the time of the burst. The GMRT observations at low frequencies are
particularly important to detect the signature of merger ejecta emission at the
peak. These observations are the most delayed searches associated with some of
these GRBs for any late-time low-frequency emission. We find no evidence for
such an emission. We find that none of these GRBs are consistent with maximally
rotating magnetar with a rotational energy of .
However, magnetars with lower rotational energies cannot be completely ruled
out. Despite the non detection, our study underscores the power of radio
observations in the search for magnetar signatures associated with short GRBs.
However, only future radio observatories may have the capabilities to either
detect these signatures or put more stringent constraints on the model.Comment: 10 pages, 4 figures, Published in MNRA
STANDARDIZATION OF A TRADITIONAL POLYHERBO-MINERAL FORMULATION- BRAHMI VATI
The present study deals with standardization of an in-house standard preparation and three marketed samples of Brahmi vati, which is a traditional medicine known to be effective in mental disorders, convulsions, weak memory, high fever and hysteria. Preparation and standardization have been done by following modern scientific quality control procedures for raw material and the finished products. The scanning electron microscopic (SEM) analysis showed the reduction of metals and minerals (particle size range 2-5 ÎŒm) which indicates the proper preparation of bhasmas, the important ingredient of Brahmi vati. Findings of EDX analysis of all samples of Brahmi vati suggested the absence of Gold, an important constituent of Brahmi vati in two marketed samples. All the samples of Brahmi vati were subjected to quantitative estimation of Bacoside A (marker compound) by HPTLC technique. Extraction of the samples was done in methanol and the chromatograms were developed in Butanol: Glacial acetic acid: water (4.5:0.5:5 v/v) and detected at 225nm. The regression analysis of calibration plots of Bacoside A exhibited linear relationship in the concentration range of 50-300 ng, while the % recovery was found to be 96.06% w/w, thus proving the accuracy and precision of the analysis. The Bacoside A content in the in-house preparation was found to be higher than that of the commercial samples. The proposed HPTLC method was found to be rapid, simple and accurate for quantitative estimation of Bacoside A in different formulations. The results of this study could be used as a model data in the standardization of Brahmi vati
Tetranuclear Group 7/8 Mixed-Metal and Open Trinuclear Group 7 Metal Carbonyl Clusters Bearing Bridging 2-mercapto-1-methylimidazole Ligands
The reactivity of group 7 metal dinuclear carbonyl complexes [M2(CO)6(ÎŒ-SN2C4H5)2] (1, M = Re; 2, M = Mn) toward group 8 metal trinuclear carbonyl clusters were examined. Reactions of 1 and 2 with [Os3(CO)10(NCMe)2] in refluxing benzene furnished the tetranuclear mixed-metal clusters [Os3Re(CO)13(ÎŒ3-SN2C4H5)] (3) and [Os3Mn(CO)13(ÎŒ3-SN2C4H5)] (4), respectively. Similar treatment of 1 and 2 with Ru3(CO)12 yielded the ruthenium analogs [Ru3Re(CO)13(ÎŒ3-SN2C4H5)] (5), and [Ru3Mn(CO)13(ÎŒ3-SN2C4H5)] (6), but in the case of 2 a secondary product [Mn3(CO)10(ÎŒ-Cl)(ÎŒ3-SN2C4H5)2] (7) was also formed. Compounds 3â6 have a butterfly core of four metal atoms with the M (Mn or Re) at a wingtip of the butterfly and containing a noncrystallographic mirror plane of symmetry. This result provides a potential method for the synthesis of a series of new group 7/8 mixed metal complexes containing a bifunctional heterocyclic ligand. Compound 7 is a unique example of a 54-electron trimanganese complex having bridging 2-mercapto-1-methylimidazolate and chloride ligands. Interestingly, the reaction of 1 with Fe3(CO)12 at 70â75 °C furnished the tri- and dirhenium complexes [Re3(CO)10(ÎŒ-H)(ÎŒ3-SN2C4H5)2] (8) and [Re2(CO)6(N2C4H5)(ÎŒ-SN2C4H5)2] (9), respectively instead of the expected formation of the mixed-metal clusters. The former is an interesting example of a 52-electron trirhenium-hydridic complex containing bridging 2-mercapto-1-methylimidazolate ligand, while the latter can be viewed as a 1-methylimidazole adduct of 1. No mixed FeâRe complexes were produced in this reaction. The molecular structures of the new compounds 3â5 and 7â9 were established by single-crystal X-ray diffraction analyses and the DFT studies of compounds 5, 7 and 8 are reported
CarbonâPhosphorus Bond Activation of Tri(2-thienyl)phosphine at Dirhenium and Dimanganese Centers
Reaction of [Re2(CO)9(NCMe)] with tri(2-thienyl)phosphine (PTh3) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re2(CO)9(PTh3)] (1), [Re2(CO)8(NCMe)(PTh3)] (2), and [Re2(CO)8(PTh3)2] (3). Complex 2 was also obtained from the room-temperature reaction of [Re2(CO)8(NCMe)2] with PTh3 and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene affords [Re2(CO)8(ÎŒ-PTh2)(ÎŒ-η1:Îș1-C4H3S)] (4) and [Re2(CO)7(PTh3)(ÎŒ-PTh2)(ÎŒ-H)] (5), respectively, both resulting from carbonâphosphorus bond cleavage of a coordinated PTh3 ligand. Reaction of [Re2(CO)10] and PTh3 in refluxing xylene gives a complex mixture of products. These products include 3â5, two further binuclear products, [Re2(CO)7(PTh3)(ÎŒ-PTh2)(ÎŒ-η1:Îș1-C4H3S)] (6) and [Re2(CO)7(ÎŒ-Îș1:Îș2-Th2PC4H2SPTh)(ÎŒ-η1:Îș1-C4H3S)] (7), and the mononuclear hydrides [ReH(CO)4(PTh3)] (8) and trans-[ReH(CO)3(PTh3)2] (9). Binuclear 6 is structurally similar to 4 and can be obtained from reaction of the latter with 1 equiv of PTh3. Formation of 7 involves a series of rearrangements resulting in the formation of a unique new diphosphine ligand, Th2PC4H2SPTh. Reaction of [Mn2(CO)10] with PTh3 in refluxing toluene affords the phosphine-substituted product [Mn2(CO)9(PTh3)] (10) and two carbonâphosphorus bond cleavage products, [Mn2(CO)6(ÎŒ-PTh2)(ÎŒ-η1:η5-C4H3S)] (11) and [Mn2(CO)5(PTh3)(ÎŒ-PTh2)(ÎŒ-η1:η5-C4H3S)] (12). Both 11 and 12 contain a bridging thienyl ligand that is bonded to one manganese atom in a η5-fashion. The molecular structures of eight of these new complexes were established by single-crystal X-ray diffraction studies, allowing a detailed analysis of the disposition of the coordinated ligands
Quantum deleting and Signalling
It is known that if we can clone an arbitrary state we can send signal faster
than light. Here, we show that deletion of unknown quantum state against a copy
can lead to superluminal signalling. But erasure of unknown quantum state does
not imply faster than light signalling.Comment: Latex file, 6 pages, no figure
A low cost PC based card for heat-capacity measurements at low temperatures
We describe a simple, low cost pc based card for the measurement of heat capacity using adiabatic calorimetry at low temperatures. This card provides the control pulse to the sample heater as well as trigger pulse to the nano-voltmeter which monitors the sensor voltage (Ge sensor, Lake Shore Inc., USA). We have also added a 12 bit DAC on this card and this is used for remote setting of the heater current of an old SHE (now Biomagnetic, Inc., USA, model CCS) analog constant current source. Although this card is used here for heat-capacity measurements, the same can also be used for thermo-power and thermal-conductivity measurements
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