Intrazeolite phototopotaxy. EXAFS analysis of precursor 8{W(CO)6}-Na56Y and photooxidation products 16(WO3)-Na56Y and 28(WO3)-Na56Y

The intrazeolite photooxidation chemistry of alpha-cage encapsulated hexacarbonyltungsten(0) in Na56Y with O2, denoted n{W(CO)6}-Na56Y/O2/hv, which has previously been shown to provide a novel synthetic pathway to alpha-cage located tungsten(VI) oxide, denoted n(WO3)-Na56Y, is now the subject of an extended X-ray absorption fine structure (EXAFS) analysis. The EXAFS data of a precursor 8{W(CO)6}Na56Y, which contains on average one W(CO)6 per alpha-cage shows that the W(CO)6 guest maintains its structural integrity with only minor observable perturbations of the skeletal WC and ligand CO bonds compared to those found for the same molecule in the free state. The EXAFS analysis results for the photoxidation products 16(WO3)-Na56Y and 28(WO3)-Na56Y are very similar and display the presence of two terminal tungsten-oxygen bonds (1.75-1.77 angstrom) and two bridging tungsten-oxide bonds (1.94-1.95 angstrom), together with a short distance to a second tungsten (3.24-3.30 angstrom). This bond length and coordination number information for n = 16 and 28 samples is best interpreted in terms of the formation of a single kind of tungsten trioxide dimer unit (WO3)2, most likely interacting with extraframework Na+ cations, denoted ZONa...O2W(mu-O)2WO2...NaOZ. In conjunction with earlier chemical and spectroscopic information on this system, the EXAFS data support the contention that 16(WO3)-Na56Y contains a uniform array of single size and shape tungsten (VI) oxide dimers (WO3)2 housed in the 13-angstrom supercages of the zeolite Y host. The sequential addition of WO3 units to the 16(WO3)-Na56Y sample appears to increase the (WO3)2 dimer population, causing a buildup of alpha-cage encapsulated dimers-of-dimers {(WO3)2}2 rather than further cluster growth to trimers (WO3)2 and/or tetramers (WO3)4

Intrazeolite metal carbonyl topotaxy. A comprehensive structural and spectroscopic study of intrazeolite Group VI metal hexacarbonyls and subcarbonyls

This paper focuses attention on the intrazeolite anchoring, thermal decarbonylation, ligand exchange, and addition chemistry of M(CO)6-M'56Y, where M = Cr, Mo, W; M' = H, Li, Na, K, Rb, Cs. The key points to emerge from this study include the following. (i) M(CO)6-M'56Y samples have the hexacarbonylmetal(O) molecule associated with two alpha-cage extraframework cations (or Bronsted protons), via the oxygen end of two trans bonded carbonyls with a saturation loading of 2M(CO)6/alpha-cage. (ii) M(CO)6-M'56Y samples have the hexacarbonylmetal(O) guest confined to the internal surface of the zeolite with a homogeneous distribution throughout the zeolite crystals. (iii) A Mo and Rb EXAFS structure analysis of 8{Mo(CO)6}-Rb56Y shows that the alpha-cage encapsulated Mo(CO)6 guest maintains its structural integrity, with some evidence for anchoring via extraframework Rb+ cations. (iv) A rapid C-13O intrazeolite ligand exchange occurs M(12CO)6-M '56Y to yield M(12CO)m(13CO)6-m-M'56Y, the extent of which depends on the 13CO loading. (v) M(CO)3-M'56Y can be cleanly generated via the mild vacuum thermal decarbonylation of M(CO)6-M56Y, the tricarbonyl stoichiometry of which is unequivocally established from its observed and calculated diagnostic M(12CO)n(13CO)3-n-M'56Y vibrational isotope pattern and from EXAFS structural data. (vi) Intrazeolite ractions of M(CO)3-M'56Y with large and small arenes, trienes, and phosphines cleanly yield the respective intrazeolite six-coordinate complexes (shown to be identical with the products of direct impregnation of the latter complexes), thereby supporting the tricarbonylmetal(0) assignment as well as pinpointing the location of the M(CO)3-M'56Y tricarbonylmetal(0) fragment on the internal surface of the zeolite. (vii) Cation effects in the mid/far-IR, EXAFS data, and optical reflectance spectra indicate that the supercage-confined M(CO)3-M'56Y moiety is anchored to an oxygen framework site rather than to an extrawork cation site via the metal or oxygens of the carbonyls. (viii) The tricarbonyl fragments show C(s) and C3-upsilon symmetry depending on the choice of M and M' which can be rationalized in terms of a second-order Jahn-Teller effect. (ix) EXAFS data for the mild thermal decomposition of Mo(CO)3-Rb56Y demonstrates the formation of molybdenum atoms statistically distributed in the zeolite lattice

Fatih Camii

[No Abstract Available

Jenis-jenis Tikus Dan Cacing Parasitnya Di DAS Sekampung, Lampung

Di Indonesia ada ±150 jenis tikus (Kadarsan& Boeadl 1975),namun baru beberapa jenis yang sudah diteliti kandungan cacing parasitnya (Kadarsan 1968, Brown et al. 1975, Carney & Stafford 1979).Padahal tikus dapat berperanan sebagai penyebar penyakit yang disebabkan cacing; kasus penyakit radang selaput otak yang diduga disebabkan cacing Angiostrongylus cantonensis dilaporkan pada pasien rumah sakit Kisaran, Sumatera Utara (Carney et al 1974) dan epidemi skistosomiasis pernah melanda penduduk Lindu, Sulawesi Tengah (Clarke et al. 1974).Mengingat pentingnya peranan tikus sebagai penyebar penyakit cacing pada manusia,dan karena kekayaan fauna cacing di Indonesia belum banyak diketahui maka suatu penelitian dilaksanakan di Dacrah Aliran Sungai Sekampung,Lampung

Doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice

New results are presented concerning the topotactic self-assembly, n-type doping and band-gap engineering of an intrazeolite tungsten(VI) oxide supralattice n(W03)-Na56Y, where 0 < η < 32, built-up of single size and shape (W03)2 dimers. In particular it has been found that the oxygen content of these dimers can be quantitatively adjusted by means of a thermal vacuum induced reversible reductive-elimination oxidative-addition of dioxygen. This provides access to new n(W03.x)-Na56Y materials (0 < χ ^ 1.0) in which the oxygen content, structural properties and electronic architecture of the dimers are changed. In this way one can precisely control the oxidation state, degree of η-doping and band-filling of a tungsten(VI) oxide supralattice through an approach which can be considered akin to, but distinct in detail to, that found in the Magneli crystallographic shear phases of non-stoichiometric bulk W03.x . Another discovery concerns the ability to alter local electrostatic fields experienced by the tungsten(VI) oxide moieties housed in the 13Ä supercages of 16(W03)-M36Y, by varying the ionic potential of the constituent supercage M + cations across the alkali metal series. This method provides the first opportunity to fine-tune the band-gap of a tungsten(VI) oxide supralattice. Α miniband electronic description is advanced as a qualitative first attempt to understand the origin of the above effects. The implications of these discoveries are that cluster size, composition and intrinsic electrostatic field effects can be used to "chemically manipulate" (engineer) the doping and band architecture of intrazeolite supralattices of possible interest in quantum electronics and nonlinear optics

Acute-on-chronic Liver Failure: MELD Score 30-day Mortality Predictability and Etiology in a Pakistani Population

Background: Cirrhosis is a pathological condition that ultimately leads to liver failure. Acute on chronic liver failure (ACLF) has a high short term mortality rate. Viral hepatitis is the most common cause of liver failure in our local population. We carried out this study to identity the 30-day mortality and etiology of patients presenting with ACLF using Model for End-Stage Liver Disease (MELD) score predictability. Methodology: This was a descriptive case series, conducted at Sheikh Zayed Hospital, Lahore, Pakistan from January 31, 2018 to July 30, 2018. One hundred and eighty five patients who met the inclusion criteria were enrolled using 95% confidence level and 4% margin of error. Data was entered and analyzed with SPSS version 23.0. Numerical variables including age was presented by Mean ± S.D. Categorical variables i.e. gender, etiology of acute-on-chronic liver failure and 30-day mortality were presented by frequency and percentage. Data was stratified for age, gender, duration of chronic liver disease and MELD grade to address the effect modifiers. Post-stratification chi-square test was calculated using 95% significance (p≤0.05). Results: Majority of the enrolled patients were male (74.6%) while only 25.4% of the patients were female. One hundred and thirty patients (70.3%) had underlying viral hepatitis while twelve patients (6.5%) and forty three patients (23.2%) presented with alcoholic liver disease and drug-induced ACLF, respectively. Eighty patients (43.2%) died within 30 days of admission.The 30-day mortality with respect to MELD grade was statistically significant (p&lt;0.001) with the highest mortality noted in grade-IV and thirty five patients (43.8%) dying within 30 days of admission (p&lt;0.001). Grade-II and III MELD scores also contributed to the 30-day mortality with twenty three patients (28.8%) and nineteen patients (23.8%) dying within 30 days of admission (p&lt;0.001). Conclusion: MELD scores are able to accurately predict the short-term mortality in patients with ACLF and viral hepatitis was the most common etiology in our population. Early detection and use of appropriate prognostic models may alleviate mortality and morbidity in paitents with ACLF

Finite Size Effects and Cooperativity in a Model Diatomic Supercooled Liquid

We use large scale molecular dynamics simulations to investigate the relation between cooperativity and size e ects in a simple diatomic supercooled liquid. We nd that below a characteristic temperature the transport properties depend on the size of the simulation box. is e ect then increases upon decreasing the temperature. For the model molecules constituting our liquid, the smaller box corresponds to the larger di usion coe cient. us, the size e ects increase the di usion of the liquid with our molecules in opposition with previous results concerning silica and atomic so molecules. As a result, the temperature dependence of the di usion coe cient tends to an Arrhenius law for smaller boxes in our simulations. is result is in agreement with a cooperativity origin of non-Arrhenius behavior and size e ects in fragile supercooled liquids, as a small box cuto cooperative motions thus inducing a constant activation energy. To investigate that picture further we then study the size dependence of cooperative motions in our model liquid.

Oxidation Behaviour and Bio-oxidation of Gold-bearing Sulphide Ores: Oxygen Capabilities and Challenges

The paper presents an overview of bio-oxidation of sulphidic refractory gold ores prior to gold cyanidation. This review discusses several factors, more importantly, oxygen requirements and oxygen limitations in biological oxidation of various sulphide minerals associated with gold ores. The availability of sufficient oxygen in bio-oxidation systems can speed up and enhance the oxidation of sulphide minerals, allowing the gold to be liberated for further extraction. However, oxygen supply and its low solubility in water have been the major limiting factors in bio-oxidation processes. More importantly, oxygen limitations are found to affect the rate of sulphide oxidation and the volume of materials that can be treated for gold leaching. First, the paper discusses the influence of dissolved oxygen on the oxidation behaviour of various sulphide minerals found in refractory gold ores or concentrates. Further discussed are the limiting factors in relation to dissolved oxygen during bio-oxidation of refractory gold ores. This review demonstrates that oxygen availability is a major challenge and therefore, oxygen enhancement techniques or strategies are vitally needed. As well, the review serves to inspire new research into efficient strategies to enhance oxygen availability

Aspects of continuity in steel and composite frames

This thesis concerns the continuity in steel and composite frame and specifically the region of the connections. It reports on five main areas as follows: 1. Seven beam-to-beam connection tests were conducted to study the structural performance of composite end plate connections. Various parameters such as the types of connections, amount of reinforcement, beams sizes, and the degree of shear connection were investigated. The investigation confirmed a similar overall response of moment-rotation (M-φ) curves to beam-to-column tests and justified the restriction by current design codes of having partial shear connection in hogging moment region. A prediction method to estimate the initial stiffness of composite connection has also been proposed. 2. The effects of concrete encasement on structural response of end plate joints of slimfloor beams were investigated. Five specimens of beam-to-column connection of slimfloor were tested. Parameters such as end plate thickness and bolt sizes are included in the study. The results have shown that proper reinforcement and design are needed if the connections are to be considered as a composite joint. 3. Tests were carried out to improve the bond capacity of encased slimfloor. A total of six push-out tests each with different type of “shear enhancer” were performed. The load at initial slip is not greatly depend on the types of enhancer and there were indications that the resistance of the enhancer only became effective after slip, due to bond failure, had occurred. 4. As far as stability of composite beams in the negative moment region is concerned, local buckling has been identified as one of the problems. The action of reinforcement may reduce many hot-rolled section to be in Class 3. Studies were conducted on published data to explore the possibility of upgrading Class 3 to Class 1. The studies indicated that beams of Class 3 web showed the characteristics of beams with higher class if the connection was full strength. Many of the Class 3 beams used in composite beams can only be upgraded to Class 2 and not to Class 1. 5. A method applicable to the design of unbraced multi-storey frames to specified limits on horizontal sway deflection is proposed. Only simple calculation are required by the method and its application is illustrated by worked example