Efficient propylene and propane separation is a major challenge in the modern chemical industry. With current separation methods being highly energy-intensive, there is a pressing need to find alternative green technology. Membrane separation emerged as a promising candidate for propylene and propane separation. Their small footprint, low cost, reliability, and environmental friendliness give membrane separation systems a competitive edge in the race towards sustainable development. The continuous advancements in material science created avenues for new membrane materials such as carbon molecular sieve (CMS) membranes which exhibit exceptional gas separation performances for challenging applications due to their strong size-sieving capabilities. In this work, a carbon molecular sieve (CMS) membrane derived from a polymer of intrinsic microporosity (TPE-PIM) has been investigated for propylene/propane separation made by pyrolysis at 400, 450, 500, 550, 600, 650, and 700 ºC. TPE-PIM-derived CMS films showed excellent pure and mixed-gas permeability and selectivity, exceeding the upper bound limits for propylene and propane. Observed in this work was the presence of an optimal pyrolysis temperature at 600 ºC, where the film showed the best performance with a permeability of 41.6 Barrer and a selectivity of 197 based on pure-gas measurements but dropping to 34 Barrer and selectivity of 33 under equimolar mixed-gas conditions. Such performance could be attributed to the unique internal structural changes that occurred during the pyrolysis. In addition, propane permeability though the CMS films was slow and required long times to reach steady-state values. Such slow kinetics illustrates the molecular sieving capabilities of CMS membranes for bigger and more condensable gases. Several characterization techniques have been performed on the films to confirm CMS formation and showcase deeper molecular structure insights. X-ray diffraction of all TPE-PIM films showed a broad spectrum at each peak due to the material’s amorphous nature. Diffraction patterns also revealed a gradual peak shift for the (002) plane towards smaller values closer to that of pure graphite. Raman spectra showed the characteristic D and G peaks for carbon films prepared at 500 ºC and above. FTIR analysis was also performed to investigate the potential formation of triazine crosslinks in the thermally treated samples, but no conclusive results were obtained.

Given a symmetric Frobenius superalgebra A equipped with a compatible involution, we define the associated Frobenius Brauer category B(A) and affine Frobenius Brauer category AB(A), generalizing the plain Brauer category B and affine Brauer category AB. We define the orthosymplectic Lie superalgebra osp m|2n(A) and a functor from B(A) to osp m|2n(A)-mod, the category of supermodules over osp m|2n(A). We also define a functor from AB(A) to the endofunctor supercategory of osp m|2n(A)-mod.We prove that these two functors are well-defined and use the former functor to prove a basis result for B(A, δ), a specialized version of B(A). Prior to defining these categories and functors, we provide the background information on super-mathematics and Frobenius superalgebras needed to understand the new results.

No description available.

The macrocyclic square planar nickel complex, [Ni II CR] 2+ , has been shown to be a useful DNA or RNA structure probe due to its highly site- and conformation specific ability to induce cleavage on exposed guanine residues via the formation of a direct guanine N7-Ni III bond. Since the postulated intermediate [Ni III CR] 3+ is unstable, the detailed mechanism is unknown. In this study, the nature of the interaction of NiCR 2+ and its oxidized products with biomolecules was investigated. A study of the conversion of [Ni II CR] 2+ between a diamagnetic square planar structure and a paramagnetic tetragonal structure in aqueous solution has shown that the conversion is affected by the identity and the concentration of the counter anion. Of the anions studied, it is clear that Br − , ClO 4 − , and CF 3 SO 3 − have a higher ability to promote the conversion to the square planar form for [NiCR] 2+ than Cl − or CF 3 COO − . The oxidation reaction of [NiCR] 2+ with either KHSO 5 or Na 2 S 2 O 8 in a molar ratio of 1/1 resulted in the same stable complex [Ni(CR-2H)] 2+ . A single crystal x-ray diffraction study gave the structure of Ni(CR-2H)(ClO 4 ) 2 . In addition, kinetic studies revealed the oxidation reaction to be first order. The six protons on the two methyl groups of the macrocyclic ligand were also found to be sufficiently labile to exhibit hydrogen/deuterium exchange. The [Ni(CR-2H)] 2+ displays a higher acidity than [NiCR] 2+ by H/D exchange. This observation supports the conjecture that there is an enhanced dπ-pπ* back-bonding effect associated with the presence of the additional imine formed in [Ni(CR-2H)] 2+ . The [NI(CR-2H)] 2+ species with KHSO 5 also displays an oxidation ability similar to [NiCR] 2+ with KHSO 5 in the reaction with a 17 base pair synthetic oligonucleotide. This implies that [Ni(CR-2H)] 2+ is not just an oxidation product of [NiCR] 2+ , but may also play an important role in the reaction with guanine residues in oligonucleotides. The reactions of [NiCR] 2+ or [Ni(CR-2H)] 2+ with linoleic acid under a high concentration of Ni complexes (3.21 × 10 −3 M, 200 fold over linoleic acid) resulted in the unexpected reduced nickel complexes, (Ni 0 (CR-4H)-H + ) − - m/z 311.1 and (Ni 0 (CR-2H)-H + ) − - m/z 313.1, instead of the hydroperoxide product (HpODE-H + ) − - m/z 311.2.

This study was designed to provide information about the mechanisms of pentaaquodihalomethyl chromium(III) ions (halo chloro, bromo and iodo). ... Mechanisms based on carbonium ion, carbeno and carbenoid type intermediates are proposed. A mechanism based on the nucleophillic attack (SN2) of water on the carbon center leading to a metal-formyl type intermediate is suggested as best fitting all the criteria observed in these studies. (see PDF file for additional Abstract as it includes formulas)

The naturally occurring polyamines play an essential role in cell growth and proliferation. The levels of polyamines have been shown to increase in rapidly proliferating cancer cells. Therefore, compounds that inhibit enzymes in polyamine biosynthetic pathway may have therapeutic potential. Compounds capable of providing both in vitro and in vivo inhibition of almost all enzymes in the polyamine biosynthetic pathway are known. An exception is the lack of an agent that inhibits spermidine/spermine N 1 -acetyltransferase (SSAT), the rate-limiting enzyme in the catabolism of polyamines. The design, synthesis and characterization of five new polyamine analogues as potential inhibitors of SSAT are presented. Three compounds, N 1 -[3-(propenamido) propyl]-1,4-diaminobutane dihydrochloride 5 , N 1 -[3-(maleimido)propyl]-1,4-diamino-butane dihydrochloride 7 and N 1 -[3-(2-bromoacetamido)propyl]-1,4-diaminobutane dihydrochloride 9 , were designed as active-site-directed affinity label inhibitors. Two compounds, N-[N-(5-acetamido-2-hydroxypentyl-3-aminopropyl)]-1,4-diaminobutane trihydrochloride 12 and N-[3-(2-hydroxyethylamino)propyl]-1,4-diaminobutane trihydrochloride 14 , were designed as transition state-like analogue inhibitors. These compounds were synthesized using one key intermediate, N-(3-aminopropyl)-N,N ′ -bis-(tert-butoxycarbonyl)-1,4-diaminobutane 3 . Three of these synthesized compounds, 5 , 7 and 12 were evaluated for their ability to inhibit SSAT. The enzyme used was a crude extract of human large cell undifferentiated lung carcinoma cell line NCI H157 cells. These synthetic analogues when tested against the crude enzyme extract at concentrations of 0.05, 0.1, 1 and 5 μM appeared to show no effects on the activity of SSAT.

Statement of the problem. This study was carried out to determine: (1) what advantages a laboratory-centered general chemistry course might have over the conventional laboratory course, and (2) whether improved understanding of laboratory work leads to better learning of chemistry. The four following questions were raised in connection with the study or this problem: What is the need for a laboratory-centered course? What has been done in the past to meet this need? Can students learn chemistry more effectively in a laboratory-centered course as compared to the conventional course? Is a laboratory-centered course to be preferred over the conventional course in teacher planning and programming?

In order to give the laboratory-centered course a trial run and to compare it with a lecture-centered course it seemed necessary to the author that both courses should be taught and compared. The latter gave rise to the following hypotheses: Students in a laboratory-centered general chemistry course show more favorable attitudes toward chemistry than do students in a lecture-centered course. Students in a laboratory-centered course show as good a subject-matter mastery as students in a lecture-centered course.

The Birch reduction of benzamide with sodium and absolute ethanol. 95% ethanol, or tert-butanol in liquid ammonia gave 1,4-dihydrobenzamide in varying amounts. The amide group was not reduced. The two most important variables encountered were the alcohol used and whether or not ammonium chloride was added after the reduction was completed. Without this addition of ammonium chloride, little or no 1,4-dihydrobenzamide was present after workup, while with its addition some 1,4-dihydrobenzamide formed whether the proton source was absolute ethanol, 95% ethanol, or tert-butanol. The highest yield was obtained with tert-butanol with ammonium chloride being added. Addition of ammonium chloride apparently prevents the disproportionation of 1,4-dihydrobenzamide to benzaminde and a tetrahydrobenzamide by neutralizing the strongly basic alkoxide which would otherwise be present. Ammonium chloride addition may also prevent air oxidation of the 1,4-dihydrobenzamide to benzamide. A blank experiment starting with 1,4-dihydrobenzamide confirmed this disproportionation.

No description available.