Thermoelastic problem for shells of revolution exhibiting temperature dependent properties

Summary Analysis of the axially symmetric steady state thermoelastic problem for thin shells of revolution is given, assuming temperature dependent elastic and thermal properties of the material. Three governing equations are established involving components of the displacement along and normal to the meridian as well as the shearing force.A multi-parameter perturbation scheme is used with two perturbation parameters, one associated with the shear modulus and the other with Poisson's ratio.Illustrative examples are solved concerning cylindrical, conical and spherical shells as well as compound shells, such as spherico-conical, conicocylindrical and conico-conical.The results presented in this paper are taken from a thesis by the first author submitted in partial fulfilment of the requirements for the Ph. D. degree at the University of Delaware. The research was supported by a grant of the National Science Foundation.     

Isolation and characterization of triterpenes from the leaves of Orthosiphon stamineus

Orthosiphon stamineus, Benth, belonging to the family Lamiaceae, is a medicinal plant growing wild in tropical countries. Seven triterpenes, ursolic acid, oleanolic acid, betulinic acid, hydroxybetulinic acid, maslinic acid, α-amyrin and β-amyrin have been isolated from the leaves of Orthosiphon stamineus. The structures of these compounds have been established by spectroscopic methods. α-Amyrin was isolated from this plant for the first time.     

Host–Guest Complexation of [60]Fullerenes and Porphyrins Enabled by “Click Chemistry”

Herein the synthesis, characterization, and organization of a first‐generation dendritic fulleropyrrolidine bearing two pending porphyrins are reported. Both the dendron and the fullerene derivatives were synthesized by Cu^I‐catalyzed alkyne–azide cycloaddition (CuAAC). The electron‐donor–acceptor conjugate possesses a shape that allows the formation of supramolecular complexes by encapsulation of C₆₀ within the jaws of the two porphyrins of another molecule. The interactions between the two photoactive units (i.e., C₆₀ and Zn–porphyrin) were confirmed by cyclic voltammetry as well as by steady‐state and time‐resolved spectroscopy. For example, a shift of about 85 mV was found for the first reduction of C₆₀ in the electron‐donor–acceptor conjugate compared with the parent molecules, which indicates that C₆₀ is included in the jaws of the porphyrin. The fulleropyrrolidine compound exhibits a rich polymorphism, which was corroborated by AFM and SEM. In particular, it was found to form supramolecular fibrils when deposited on substrates. The morphology of the fibrils suggests that they are formed by several rows of fullerene–porphyrin complexes.     

Novel Synthesis of Pyrido[2,1-B]Benzothiazoles and 1,3-Benzothiazole Derivatives

Abstract

A variety of new pyrido[2,1-b]benzothiazole and benzothiazoles, have been prepared via the reaction of 2-substituted methylthiazole with α,β-unsaturated nitriles and activated methylene compounds. The structures of the reaction products were established based on the elemental analyses and spectral data (IR, ¹H-, ¹³C-NMR, MS).     

SOME REACTIONS OF CHOLESTERYL N-PHENYL-PHOSPHORAMIDIC CHLORIDE AND RELATED COMPOUNDS

Abstract

Cholesteryl N-phenylphosphoramidic chloride has been converted to the corresponding phosphoramidic hydrazide and azide. The former compound was characterised by the preparation of a number of hydrazones, while the latter has been reacted with norbornene, dimethylsulphoxide, and triphenylphosphine. However, the azide did not react with decane, o-anisole, or butylamine. 17-Oxoandrost-5-ene-3β-yl N-phenylphosphoramidic chloride was prepared and was converted to the hydrazide, but a pure sample of the azide could not be isolated. Cholesteryl N-phenyl phosphoramidic triphenylphosphinimine has been reacted with eight carbonyl compounds and the structures of the products investigated. Cholesteryl N-cyclohexylphosphoramidic chloride was converted to the azide and the triphenylphosphinimine; the latter was reacted with acetone and p-nitrobenzaldehyde.

Cholesteryl phosphorodichloridate has been condensed with phenol, p-nitrophenol, and p-methoxyphenol to give the corresponding O-arylphosphorochloridates. The O-phenyl and O-p-methoxyphenyl phosphorochloridates have been converted to the corresponding azides, but the azide from the p-nitrophenyl derivative could not be isolated. The reactions of cholesteryl phosphorodichloridate with diethylamine, hydrazine, and sodium azide have also been examined; and cholesteryl phosphorodichloridothioate has been condensed with aniline and benzylamine.     

Structurally Enhanced Hydrogel Nanocomposites with Improved Swelling and Mechanical Properties

In this work, structurally enhanced hydrogel nanocomposites based on 2-acrylamido-2 methyl propane sulfonic acid (AMPS)-acrylamide (AAM) copolymer with high hydrophilic group content were prepared by in-situ copolymerization by using different types of clay (montmorillonite, mica and halloysite). Nanocomposite hydrogels were characterized by Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses and determination of swelling degrees of the samples. Mechanical properties of the samples were also investigated by determination of the compressive elastic modulus. It was also found that exfoliated or highly expanded intercalated nanocomposite structure was obtained and clay incorporation into the AMPS-AAM hydrogel structure improved its swelling capacity. The highest swelling capacity (1030 g H₂O/g) was observed for the nanocomposite sample prepared with the montmorillonite amount of 5% (w). Furthermore, mechanical strength of the hydrogels against compression forces was significantly improved by the clay addition. It was found that the type of clay, in other word filler geometry, affected the compressive elastic modulus (E) of the samples. It was concluded that halloysite, which is considered to be a one dimensional (1D) nanotubular filler was less effective to enhance the compressive elastic modulus (E) of such materials compared with the montmorillonite and mica having two dimensional (2D) platelet or disk-like shapes at a particular amount of clay.     

Enhanced Electrocatalytic Oxidation of Paracetamol at DNA Modified Gold Electrode

Cysteine monolayer has been assembled onto bare gold electrode (SAM/Au), and subsequently deoxyribonucleic acid (DNA) has been successfully immobilized at the SAM/Au electrode. The thus modified electrode is assigned DNA/SAM/Au. Modification steps of the electrode were followed electrochemically using K₄[Fe(CN₆)] electrochemical marker. Also, the build‐up of the modified electrode composition is followed using EDX and the crystallographic orientation is inspected using XRD. The electrochemical behavior of paracetamol (PC) at DNA/SAM/Au electrode is investigated. Interestingly, the sluggish irreversible behavior of PC at the bare gold electrode is converted to a quasi‐reversible one at DNA/SAM/Au electrode pointing to some interaction between the immobilized DNA and PC. The enhanced electrochemical behavior of PC at modified DNA/SAM/Au electrode is successfully used for a sensitive electrochemical determination of PC. Square wave voltammetry (SWV) was used for this purpose. The concentration of PC was in linear relation with the peak current at the optimum conditions within the range 10.0–110.0 μg mL^?1 with correlation coefficient (R²) of 0.998. Also, the standard deviation (SD) and relative standard deviation (RSD) were calculated and found to be 0.817 and 1.52, respectively, indicating the significance of the present method.     

Phenothiazine-Biaryl-Containing Fluorescent RGD Peptides

Cyclic RGD peptides are well-known ligands of integrins. The integrins α_Vβ₃ and α₅β₁ are involved in angiogenesis, and integrin α_Vβ₃ is abundantly present on cancer cells, thus representing a therapeutic target. Hence, synthetic and biophysical studies continuously are being directed towards the understanding of ligand-integrin interaction. In this context, the development of versatile synthetic strategies to obtain fluorescent building blocks that can add molecular diversity and modular spectral characteristics while not compromising binding affinity or selectivity is a relevant task. An on-resin intramolecular Suzuki–Miyaura cross-coupling (SMC) between l - or d -7-bromotryptophan (7BrTrp) and a phenothiazine (Ptz) boronic acid affords fluorescent cyclic RGD pseudopeptides, c(RGD(W/w)Ptz). Ring closure by SMC establishes a phenothiazine–indole moiety with axial chirality. An array of eight novel compounds has been synthesized, among them one fluorescent compound with good affinity to integrin α_Vβ₃. The fluorescence properties of the analogues can be efficiently tuned depending on the substituents in Ptz moiety even for fluorescence emission in the visible (red) spectral range.     

Design,synthesis, and in vitro anticancer screening of novel pyrazolinyl-pyrazole/1, 2, 3-triazole hybrids

Novel hybrids, pyrazolinylpyrazoles, and pyrazolinyltriazoles were designed, synthesized, and screened for their anticancer activity. Eleven compounds were selected by the National Cancer Institute (NCI)/USA for anticancer screening at single high dose (10⁻⁵ M) in full NCI 60 cell panels. Two compounds: 4-aminopyrazole-5-carbonitrile, 5c (NSC-747630/1) and ethyl 4-aminopyrazole-5- carboxylate, 7d (NSC-747634/1) were the most active candidates of the series and were selected for further evaluation at five dose screening as they displayed significant growth inhibition with full panel median growth inhibition (GI₅₀) 5.47 and 2.24 μM, respectively. Both 5c and 7d hybrids exhibited broad spectrum antitumor activity; however 7d showed moderate selectivity (selectivity ratio 3.6) toward leukemia.     

Molecular docking and biological assessment of substituted phthalazin-1(2H)-one derivatives

2, 4-Disubstituted phthalazin-1(2H)-one derivatives were synthesized via nucleophilic attack of N-2 of phthalazin-1(2H)-one derivatives on different alkyl halides. In addition, reactive phthalazinone acetohydrazide derivative was utilized as a scaffold to synthesize different heterocyclic systems. The assigned structures for all the newly synthesized derivatives were confirmed on the basis of elemental analyses and spectral data. Mechanistic illustrations for some of the synthesized compounds were also discussed. The synthesized compounds were evaluated for in vitro antimicrobial and antitumor activity. Most of the tested compounds exhibited significant potency as antimicrobial and antitumor agents. Moreover, MOE 2014.09 software was utilized to carry out computational studies to support the biological activity results.