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Research shows that the viscosity greatly reduction of viscous crude oil can improve the exploitation and promote the fluidity. We studied the effects and the mechanism of viscosity reduction of vi...

An Advanced Heavy Water Reactor (AHWR) has been specifically designed to exploit Th/233U as fuels. The reprocessing is focused mainly on the recovery of 233U and Pu from the spent fuels leaving bulk of Th (∼100 g/L) in the High Level Waste (HLW) solutions. No systematic attempts have been made so far to identify suitable solvents for the recovery of thorium from high level waste (HLW) solutions generated after AHWR spent fuel reprocessing. Tri-n-butyl phosphate (TBP), though the work horse for nuclear fuel reprocessing as an extractant, suffers from the serious limitation of third-phase formation during the extraction of macro concentrations of thorium. Two straight chain dialkyl amides such as N,N-dihexyl octanamide (DHOA), and N,N-dihexyl decanamide (DHDA) as well as TBP were evaluated for the recovery of the thorium from AHWR-HLW solutions. Attempts were made to identify suitable solvent (extractant + diluent) system and optimize the conditions for the recovery of thorium from HLW solutions. Selectivit...

Solvent extraction studies carried out at BARC, India on the evaluation of N,N-dialkyl amides as alternative extractants to tri-n-butyl phosphate (TBP) for reprocessing of spent fuel have suggested that straight chain N,N-dihexyloctanamide (DHOA) is promising alternative to TBP for the reprocessing of irradiated uranium based fuels. This paper presents the batch as well as mixer settler studies for uranium and plutonium extraction/stripping to evaluate DHOA vis a-vis TBP for the reprocessing of Pu rich fuels. These studies showed that uranium extraction using DHOA as extractant was comparable to that of TBP; however, it displayed better stripping behavior than TBP. Plutonium extraction behavior was better in the case of DHOA as compared to that of TBP. However, Pu stripping data indicated towards the need of reducing agent in the stripping cycle for both the extractants.

The effect of some low molecular weight straight-chain diamines to inhibit the corrosion of SS type 304 in 1 M HCl solution is examined by weight loss and galvanostatic polarization techniques. The inhibition efficiency increases with increasing the number of carbon atoms in the chain up to 8 carbons, but at higher than 8 carbon atoms (12 carbons) it decreases again. These diamine compounds act as mixed-type inhibitors, but the cathode is more polarized than the anode when an external current was applied. The corrosion rate in the presence of the investigated diamine compounds was found to increase with increasing the temperature and decrease with increasing the concentration of these compounds. Activation parameters for the corrosion of SS in 1 M HCl were calculated and showed that corrosion was much reduced in the presence of inhibitors. The adsorption of these compounds on SS from 1 M HCl solution obeys the Langmuir adsorption isotherm. The synergistic effect of KI on the inhibitive efficiency of the i...

With the help of low-frequency Raman spectroscopy, the peculiarity of structural organization of oriented PE produced by multistage zone drawing of melt-crystallized films was studied. The draw ratios varied from DR=6 to 21 for PEI with Mη=8·104 and from 3.5 to 5.7 for PEII with Mη≈106. The half widths (Δν) of all observed LAM bands were larger than 10–20 cm−1. This means that the bands comprise a continuum of the overlapped elementary bands with Δν≈3 cm−1 because of the wide straight–chain segments (SCS) length distribution. The length (L) of straight segments calculated from LAM-spectra, following a routine procedure, lies in the range from 7–8 to 60 nm. Weight fractions GMW of the SCS, as functions of their length, have a bell-like shape. Comparison of the SCS lengths with the value of the long periods (D) inferred from SAXS data for the same samples indicates that the lengths do not exceed 2D. The structural interpretation of the data obtained is given on the basis of microfibrillar models of oriented...

Synthetic dispersants can greatly increase the solubility of asphaltenes in crude oils at low concentrations. They have one or more head groups that complex with the polynuclear aromatic structures in asphaltenes and long paraffinic tails that promote solubility in the rest of the oil. As a result, synthetic dispersants can be much more effective than the natural dispersants in the oil, the resins. At high concentrations, synthetic dispersants can even make all the asphaltenes soluble in n-heptane and thereby convert asphaltenes to resins. Asphaltene dispersants were optimized according to their ability to reduce the toluene equivalence of 05a crude oil. By synthesizing families of prospective dispersants, one sulfonic acid group was determined to be the most effective head attached to a two ring aromatic structure. As previously reported, a straight chain paraffinic tail is not effective above 16 carbons. We discovered that this was because of decreased solubility in the oil caused by crystalliz...

The interfacial tension (IFT) of 1 M solutions of N,N-dialkyl amide in n-dodecane against water and nitric acid has been measured at 303K. Ten amides, namely, dibutyl hexanamide (DBHA), diisobutyl hexanamide (DiBHA), dibutyl octanamide (DBOA), dihexyl hexanamide (DHHA), dibutyl dodecanamide (DBDA), di n-octyl butanamide (DOBA), diisooctyl butanamide (DiOBA), di n-octyl isobutanamide (DOiBA), di n-hexyl octanamide (DHOA), and di n-octyl hexanamide (DOHA) were synthesized and used. The effect of concentration of DOHA on IFT against 3 M nitric acid was also studied. It was observed that the introduction of branching in an amide on either the acyl or the nitrogen side increases the IFT over its straight chain analogue, as in the case of DiOBA, DOiBA, and DiBHA. Increasing the carbon chain length on the acyl side, keeping the total carbon number constant, was found to increase the IFT considerably. Increasing the concentration of the amide resulted in a decrease in the IFT values, due to the lowering of the concentration of hydrophobic diluent. An increase in the uranium loading of the organic phase in the case of 1 M DOHA, was found to increase the IFT.

We have performed both conventional canonical molecular dynamics (MD) and multicanonical MD (MMD) simulations for a single di-block polyampholyte in vacuum to investigate possible structural phase transitions. The conventional canonical MD simulation for temperature T∗ > 0.05 gives reliable results, since these are independent of the initial conformation. The MMD simulation results for temperature T∗ > 0.05 are in good agreement with those of the conventional canonical MD simulation. Glassy-like states are obtained when quenched into temperatures below T∗ > 0.05 with a straight chain structure as an initial conformation. On the other hand a spherical double helical structure is obtained when the temperature is gradually lowered to T∗ > 0.01. Also we find a stretched double helical structure at T∗ ∼ 0.01 which changes to the spherical double helical structure by annealing and quenching.

Stereoselective reduction of a triple C-C bond and chemoselective transformation of an azide function into amino group have been employed in the synthesis of straight-chain primary E and Z allylic amines from alk-2-yn-1-ols.

Wear and degradation as exhibited by degassing of three commercially available perfluoroalkylpolyethers, A, straight chain with acetal linkage (OCF2CF2)p(OCF2)q;B, straight chain without acetal linkage (CF2CF2CF2O)n; C, branched chain (CFCF3CF2O)m, were evaluated at 0.025 mis under 1 to 300 N at 10−5 Pa in a four-ball configuration using 440C and Si3N4 balls, Φ:6.35 mm, as test specimens. A quadrupole mass spectrometer having a mass range of 1 to 200 amu was employed to analyze gaseous products released from the sliding surfaces. Disregarding the gas released, Oil C showed slightly better wear characteristics than B, but far better than A when tested with a 440C ball on 440C balls. Taking gas evolution into account, Oil B carried the highest load; the initial degassing was detected at the Hertzian pressure of 1 GPa for A, 2 GPa for B, and 1.75 GPa for C when using 440C balls, and at 1.5 GPa for A and 2.75 GPa for C when using Si3N4 balls. Oil B evaluated with Si3N4 balls did not evolve gases even at 2.75 ...

A convenient method has been developed to selectivly form the monotriphenylmethyl derivatives of symmetric 1,n-diols, both straight chain and cyclic, in moderate to high yields.

Tri(2-ethylhexyl) amine (TEHA) was found to be a considerably weaker extractant for mineral acids than straight chain aliphatic amines. It is still, however, markedly stronger than solvating extractants such as alcohols and esters. Its medium strength provides for a relatively wide range of efficient and reversible extraction. TEHA and similarly branched chain tertiary amines are therefore suitable for recovery of strong mineral acids from effluents containing them in low concentrations. Effects of diluents and modifiers and of amine concentration were found to provide a strong tool for adjusting the range of efficient and reversible extraction to characteristics of treated solutions.

A mathematical model is developed to determine the deposition of straight chain aggregates in the human respiratory tract. The expressions for collection efficiencies of various deposition mechanisms, both in the airways and in the head region, are derived. Total and regional results are obtained for aggregates of different primary sphere diameters and for different numbers of spheres in the chain.

A procedure has been developed for the detection and quantification of the straight chain fatty acids from propionic (C3) to decanoic (C10) acid using post‐column reaction detection. This method utilizes the change in color produced when the acids are mixed with the pH indicator, neutral red, following separation on a phenyl‐bonded phase column. As each of the acids elutes from the column, they mix with an aqueous solution of the indicator and 0.01 M boric acid at pH 6.80. The change in the concentration of the protonated form of the dye allows for quantification of the acids at 533 nm.

Many derivatives of cholesterol form cholesteric liquid crystal phases and these have wide application in medicine and technology. In particular the straight chain alkyl esters of Cholesterol occur in arterial fatty deposits and a knowledge of the crystalline forms and mesophases of these compounds may explain the conditions of formation of the deposits and ultimately lead to preventative measures.1–4

A variety of homologous 1-deoxy-1-(N-methylalkamido)-D-glucitols were prepared and their liquid crystal phases characterized. In this study the thermotropic liquid-crystalline properties of these materials are investigated. The mesophases formed are shown to be of the smectic A class with an interdigitated bilayer ordering of the constituent molecules. This ordering is thought to be stabilized by hydrogen-bonding between neighbouring carbohydrate moieties. The properties of these materials are compared with those of other closely related acyclic carbohydrates.

A comparison is made between measured species concentrations in a spark ignition engine and predictions from a numerical model using detailed chemical kinetics. Gas samples are extracted from the end gas at times just prior to autoignition of n-butane/air oriso-butane/air mixtures. Concentration histories of stable species are ohtained through gas chromatographic analysis. A detailed chemical kinetics model is used to predict species concentrations in an idealized end gas. The chemical reactions leading to formation of the relevant species are identified. The relative distribution of intermediate products predicted by the model is in good agrrement with the experimental measurements. Chemical kinetic differences between autoignition of n-butane, a straight chain hydrocarbon, and iso-butane. a branched chain hydrocarhon. are discussed.

The analysis of silicate anions present in Portland cement using the trimethylsilylation technique, using modifications to the original methods described by Lentz and Tamas, have provided contrasting results. The Lentz method yields a large proportion of high molecular weight polyorganosiloxane derivatives of cyclic and straight silicate anion species. The Tamas method indicates the presence of initially straight chain and later cyclic anions that condense on prolonged hydration to form multicyclic species based on a cyclic octamer. The polyorganosiloxanes were separated and identified using conventional chromatography methods and anisotropic solvent induced shift 1H nuclear magnetic resonance. The susceptibility of the Lentz method to side reactions and the superiority of the modified Tamas method in reducing these reactions were demonstrated.MST/691

Townsend primary and secondary ionization coefficients have been measured and spark voltages deduced for pentene-1, hexene-1 and their cyclo-derivatives up to their respective saturation vapour pressure, corresponding to 48  E/po  2000 V cm–1 torr–1 at 0°C and voltages up to 500 kV. The Townsend equation α/po = A exp (— Bpo/E) is found to bo oboyed over an α/po range of 1000 to 1 and the constants A and B are deduced. This allows the cyclo-olefins to bo correctly categorized in relation to their straight chain counterparts. Giant avalanches in the region of exp (αd) = 108 have again been measured. A short historical survey of this discovery is given together with a. novel application.

Esters in the homologous series 4-alkoxyphenyl 4'-alkylbenzoates, 1a, have been synthesized with both straight and methyl-branched R-groups from C3-C6, plus n-C9 and n-C10 and with straight chain R...

The history of polyolefins actually began in the 1890s with the synthesis of polymethylene from diazomethane. In the 1930s researchers in England discovered that ethylene at high pressure and in the presence of oxygen polymerized to a high molecular weight resin. Further research there and in the United States at still higher pressures yielded essentially straight chain, higher density polyethylenes. Early in the 1950s, groups in the United States and Europe independently discovered that linear, high-density polyethylenes could be made at low pressure over heterogeneous catalysts. Concurrently, groups catalytically produced polyolefin plastics from propylene and higher a-olefins. The inventorship of crystalline polypropylene was awarded to Phillips Petroleum Co. by United States courts in early 1980 (subject to final appeal). Commercial production of low-density polyethylene began in England (ICI) in 1939. High-pressure plants appeared in the United States (Du Pont and Union Carbide) and in Germa...

In the 26 years since the term “shape-selective catalysis” was coined by P. B. Weisz and V. J. Frilette [1] to describe the unique catalytic properties of small pore molecular sieve zeolites, great strides in the use of shape-selective zeolites have been made, both scientifically and technologically. Since then, in addition to small pore zeolites, synthetic medium pore zeolites, such as ZSM-5 [2], ZSM-11 [3], ZSM-22 [4], ZSM-23 [5], ZSM-35 [6], ZSM-38 [7], ZSM-48 [8], etc., have been discovered. The availability of these synthetic medium pore zeolites has expanded the realm of “shape selectivity” beyond the original discovery of selective conversion of straight chain molecules to include certain branched molecules, single-ring aromatics, naphthenes, and nonhydrocarbons with a critical molecular dimension smaller than about 6 A.

The unit cell dimensions and space groups of the common n-alkyl esters of cholesterol (with the exception of the propanoate) have been determined by single crystal X-ray diffraction studies. No overall structural pattern is evident for this series but there are small groups of esters whose structures appear to form regular sequences. Using X-ray powder photography, the crystalline solid phases of the esters obtained from solution were compared with those obtained by cooling the melt. In the majority of cases there are no significant differences but for the mcthanoate, ethanoate, butanoate, pentanoate and dodecanoate there appears to be solid state polymorphism.

The composition of the essential oil from Hemizygia welwitschii twigs was analyzed by means of GLC, LSC and GC/MS. The portion investigated so far consisted of 51% sesquiterpene hydrocarbons, 17% monoterpene hydrocarbons, 17% oxygen-containing sesquiterpenes, 6% oxygencontaining monoterpenes and 2% oxygen-containing, straight chain aliphatic compounds. The main components were β-caryophyllene (35%) and trans-α-bergamotol (11%); this is the first reported occurrence of the latter compound in Lamiaceae. The composition of the oil of H. welwitschii has not been reported previously. Additionally, 30–40% diterpenes were detected in the total oil.