254 research outputs found
A half-century of metal and metalloid-containing polymers
No full textAlaa S. Abd-El-Aziz ... [et al.]; Includes bibliographical references and indexes.; Editor, Alaa S. Abd-El-Aziz, is currently President of the University of Prince Edward Island.Source type: Electronic(1
Effect of wall conduction on natural convection heat transfer in attic spaces / by Alaa Hussein Abdel Samad.
No full textThesis (M.M.E.)--American University of Beirut, Department of Mechanical Engineering, 2012.;"Advisor : Dr. Fadl Moukalled, Professor, Mechanical Engineering--Members of Committee : Dr. Marwan Darwish, Professor, Mechanical Engineering Dr. Kamel Aboughali, Associate Professor, Mechanical Engineering."Includes bibliographical references (leaves 76-78)In this study, steady natural convection heat transfer in trapezoidal enclosures is investigated numerically under winter-like and summer-like boundary conditions. These enclosures represent attic spaces with pitched roofs that are widespread in Lebanon. A two-dimensional model of the attic space is used to study the effect of the walls and ceiling conductivities on the natural convection heat transfer within the attic. During winter conditions the maximum height of the attic is considered to be 2 m with a span of 15 m. With the prevailing weather conditions in Lebanon, during winter the base wall is heated at 295 K whereas the vertical and inclined walls are exposed to an ambient wind stream at 276 K. On the other hand during summer conditions, the maximum height of the attic is considered to be 1 m with a span of 7.5 m. The base wall is cooled at 295 K while the vertical and inclined walls are exposed to an ambient air stream at 305 K. The thermal and geometrical conditions that are considered here lead to Rayleigh numbers in the order of 10⁹ and 10⁸ under winter and summer boundary conditions respectively. Using the two-dimensional model, different walls conductivities are studied for two ceiling assemblies having U-values of 3.12 and 0.49 W-m2°K, representing, respectively, conventional non-insulated and recommended roof by the Lebanese thermal standard. A three-dimensional model representing the attic space is also developed to study the actual flow during summer conditions. For computational analysis, turbulence is modeled using a low-Reynolds number k-omega model with the governing equations discretized using a finite-volume approach. The Semi-implicit method for pressure linked equation (SIMPLE) algorithm is employed to resolve the pressure-velocity coupling with the convection terms discretized using the second order upwind scheme. For every case studied, the average heat transfer rates are calculated and presented to underscore the differences. Moreover flow patterns and isotherms a
R02. HIV-1 Tat Promotes Age-Related Anxiety-like, Antinociceptive, and Neuromuscular Impairments in Aged Male Mice
No full textCorresponding author (BioMolecular Sciences): Alaa Qrareya, [email protected]://egrove.olemiss.edu/pharm_annual_posters/1001/thumbnail.jp
Properties of the [M(dppm)2M']2+ building blocks (M, M' = Pd or Pt): site selectivity, emission features, and frontier orbital analysis.
No full textThe homodinuclear [ClM(μ-dppm)2MCl] complexes 1 (M = Pd) and 2 (M = Pt) react with RNC ligands (R = Ph, xylyl, p-tolyl, p-C6H4iPr) to provide the A-frame [ClPd(μ-dppm)2(μ-C:N-R)PdCl] (R = Ph (5a), xylyl (5b)), [ClPt(μ-dppm)2(μ-C:N-R)PtCl] (R = p-tolyl (4a); p-C6H4iPr (4b)), and the d9-d9 M2-bonded [ClPt(μ-dppm)2Pt(CN-R)]Cl (R = xylyl (3a); p-C6H4iPr (3b)) complexes. The heterodinuclear [XPd(μ-dppm)2PtX] complexes 6a (X = Cl) and 6b (X = I) react with RNC (R = o-anisyl) to form the A-frame [XPd(μ-dppm)2(μ-C:N-R)PtX] (X = Cl (9); I (10a)) and M2-bonded [ClPt(μ-dppm)2Pt(CN-R)]Cl (10b) complexes. The dangling ligand-contg. complex [ClPd(μ-dppm)2Pt(η1-dppm:O)](BF4) (7) reacts with xylyl-NC stoichiometrically to produce the dicationic salt [(xylyl-NC)Pd(μ-dppm)2Pt(η1-dppm:O)](BF4)2 (8). Parameters ruling the coordination site terminal vs. bridging are discussed. The precursor 10a reacts with RNC (R = o-anisyl, tBu) to form the heterobimetallic bis(isonitrile) [IPd(μ-dppm)2(μ-C:N-o-anisyl)Pt(CN-R)]I complexes 11b and 12, resp., demonstrating the site selectivity of the second CNR ligand coordination, Pd vs. Pt. The x-ray structures of 11b and 12 were obtained. Complex 12 is the first example of an A-frame system of the Ni-triad bearing two different isocyanide ligands. Several d9-d9 terminal and d8-d8 A-frame homo- and heterodinuclear complexes in 2-MeTHF at 77 K were studied by UV-visible and luminescence spectroscopy. Assignments for the lowest energy absorption and emission bands are made from d. functional theory and time-dependent d. functional theory computations. [on SciFinder(R)
Correction: Saadah et al. Developing Robust Safety Protocols for Radiosurgery within Patient Positioning System Framework. Machines 2024, 12, 106
No full textAfter the publication of the paper, Endre Takacs from Clemson University contacted the corresponding author Alaa Saadah to ask for multiple individuals (Laszlo Fadgyas, Jason Henderson, Tibor Koroknai, Máté Koroknai, David Takacs, Peter Panko, and Endre Takacs) to be added as additional co-authors of the original publication [...
The diagnostic accuracy of intraoperative frozen section biopsy for diagnosis of sentinel lymph node metastasis in breast cancer patients: a meta-analysis
No full textSentinel lymph node (SLN) sampling is important for evaluating the nodal stage of breast cancer when the axillary nodes are clinically free of metastasis. The intraoperative frozen section (IFS) of SLN is used for lymph node assessment. This meta-analysis aims to provide evidence about the diagnostic accuracy and the applicability of IFS of SLN in breast cancer patients. Data were collected by searching PubMed, Cochrane, Scopus, and Web of Science electronic databases for trials matching our eligibility criteria. The statistical analysis included the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and pooled studies’ diagnostic odds ratio outcomes. The analyses were conducted using the Open Meta-analyst software. This meta-analysis pooled the results of 110 studies. The overall sensitivity of IFS for SLN metastasis was 74.7%; 95% CI [72.0, 77.2], P < 0.001. It was 31.4% 95% CI [25.2, 38.3], P < 0.001 for the micro-metastasis, and 90.2%; 95% CI [86.5, 93.0], P < 0.001 for the macro-metastasis. The overall specificity was 99.4%; 95% CI [99.2, 99.6], P < 0.001. The overall positive likelihood ratio was 121.4; 95% CI [87.9, 167.6], P < 0.001, and the overall negative likelihood ratio was 0.226; 95% CI [0.186, 0.274], P < 0.001. The overall diagnostic odds ratio of IFS for diagnosing SLN metastasis was 569.5; 95% CI [404.2, 802.4], P < 0.001. The intraoperative frozen section of SLN has good sensitivity for diagnosing breast cancer macro-metastasis. However, the sensitivity is low for micro-metastasis. The specificity is very satisfactory. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11356-022-20569-4
Iron cyclopentadienyl mediated 2-alkyl-2-arylphenylsulfonylacetonitrile synthesis.
No full textA unique route to the synthesis of 2-alkyl-2-arylphenylsulfonylacetonitriles via the nucleophilic arom. substitution (SNAr) of (chloroarene)cyclopentadienyliron complexes with 2-alkyl phenylsulfonylacetonitriles was studied. Reactions of chloroarene complexes with 2-alkyl phenylsulfonylacetonitrile in the presence of K2CO3 in DMF at room temp. gave I (R1 = H, o-, m-, p-Me; R2 = Et, Bu) in good yields. The use of alkylated phenylsulfonylacetonitriles as nucleophiles in the reactions with the p-dichlorobenzene complex gave I (R1 = CR2(CN)(SO2Ph), R2 = Et, Bu). Photolytic demetalation provided an efficient route to the liberation of the arylated phenylsulfonylacetonitriles
Homogeneous degradation of 1,2,9,10-tetrachlorodecane in aqueous solutions using hydrogen peroxide, iron and UV light
No full textThe homogeneous degradation of the polychlorinated n-alkane, 1,2,9,10-tetrachlorodecane (T4C10), was studied in aqueous solutions of hydrogen peroxide, including Fenton and photo-Fenton reaction conditions. All solutions were adjusted to a pH of 2.8 and an ionic strength of 0.1 M NaClO4 prior to photolysis. T4C10 (2 x 10(-6) M) was substantially degraded by the H2O2/UV system (1.0 x 10(-2) M H2O2), with 60% disappearance in 20 min of irradiation in a photoreactor equipped with 300 nm lamps of light intensity 3.6 x 10(-5) Ein L(-1) min(-1) (established by ferrioxalate actinometry). The reaction produced stoichiometric amounts of chloride ion indicating complete dechlorination of the chlorinated n-alkane. T4C10 degraded very slowly under Fenton (Fe2+/H2O2/dark) and Fenton-like (Fe3+/H2O2/dark) conditions. However, when the same solutions were irradiated, T4C10 degraded more rapidly than in the H2O2/UV system, with 61% disappearance in 10 min of exposure. The rapid degradation is related to the enhanced degradation of hydrogen peroxide to oxidizing *OH radicals under photo-Fenton conditions. Degradation was inhibited in both the H2O2/UV and photo-Fenton systems by the addition of KI and tert-butyl alcohol due to *OH scavenging
Epic of the palm tree in Los Angeles
No full textThesis: M. Arch., Massachusetts Institute of Technology, Department of Architecture, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 84-85).The Palm Tree of Los Angeles is it's own entity. It is spelled with a capital P and T. It is also inherently contranymic. (A contranym is defined as a word with two opposite meanings.) Although referred to as "tree," it biologically is not. It is a monocot, similar to grass. Although it is completely embedded into the making of Los Angeles, it is not native to the city at all. Different palm trees from around the world, along with their stories, have participated in constructing myths continuously perpetuated in and by Los Angeles. Current myth making, however, perpetuates a flat, simple narrative. This thesis brings multiple dimensions of positive and negative narratives forward in one continual experience, collapsing these into an alternative mythology. The proposal moves from a flat representation to a collapsed representation. Flat representation is when the myth references only a single story, whereas collapsed representation allows the myth to reference multiple stories. This shift is a new approach on reading the city's history, creating an alternative mythology. By using an aesthetic of Persian miniatures, the thesis re-orientalizes representations of the palm tree. I use the term re-orientalize intentionally, also calling to a re-orienting of the interpreter. This thesis uses a flat aesthetic, but tells a collapsed mythology. The proposal is architecturalized through a series of interventions in the city that can be approached either on their own, or as a constructed loop. The series of interventions are put together as a "nameh," which is a book from a Persian tradition that tells a type of history through painting and verse. This is the Palmnameh: The Epic of The Palm.by Alaa Quraishi.M. Arch
Triplet energy transfers in electrostatic host-guest assemblies of unsaturated organometallic cluster cations and carboxylate-containing porphyrin pigments.
No full textThe unsaturated cyclic [M3(dppm)3(CO)](2+) clusters (M = Pt, Pd; dppm = Ph2PCH2PPh2; such as PF6(-) salt) exhibit a cavity formed by the six dppm-phenyl groups placed like a picket fence above the unsaturated triangular M3 dicationic center. Electrostatic interactions of the M(3+) units inside this cavity with the carboxylate anion RCO2(-) [R = tetraphenylporphyrinatozinc(II), ZnTPP; p-phenyltritolylporphyrinatozinc(II), ZnTTPP; p-phenyltritolylporphyrinatopalladium(II), PdTTPP] form dyads for through-space triplet energy transfers. The binding constants are on the order of 20,000 M(-1) in all six cases (298 K). The energy diagram built upon absorption and emission spectra at 298 and 77 K places the [Pt3(dppm)3(CO)](2+) and [Pd3(dppm)3(CO)](2+) as triplet energy donors, respectively, with respect to the ZnTPPCO2(-), ZnTTPPCO2(-), and PdTTPPCO2(-) pigments, which act as acceptors. Evidence for energy transfer is provided by the transient absorption spectra at 298 K, where triplet-triplet absorption bands of the metalloporphyrin chromophores are depicted at all time (at 298 K) with total absence of the charge-separated state in the nanosecond to microsecond time scale. Rates for energy transfer (ranging in the 10(4) s(-1) time scale) are extracted from the emission lifetimes of the [Pt3(dppm)3(CO)](2+) donor in the free chromophore and the host-guest assemblies. The emission intensity of [Pd3(dppm)3(CO)](2+) is too weak to measure its spectrum and emission lifetime in the presence of the strongly luminescent metalloporphyrin-containing materials. For the [Pd3(dppm)3(CO)](2+)...metalloporphyrin dyads, evidence for fluorescence and phosphorescence lifetime quenching of the porphyrin chromophore at 298 K is provided. These quenchings, exhibiting rates of 10(4) (triplet) and 10(8) s(-1) (singlet), are attributed to a photoinduced electron transfer from the metalloporphyrin to the cluster due to the low reduction potential.Source type: Electronic(1
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