Unit Increases Research Articles

Synthesis of Fullerodendrons with an Ammonium Unit at the Focal Point and Their Cooperative Self‐Assembly on a Fluorescent Ditopic Crown Ether Receptor

Dendritic branches with 1, 2, or 4 peripheral fullerene subunits and an ammonium function at the focal point have been prepared. Their ability to form self-assembled dendritic structures with oligophenylenevinylene receptors bearing one or two crown ether moieties has been evidenced by ES-MS studies for the first time. These supramolecular complexes are multicomponent photoactive devices in which the emission of the central receptor is dramatically quenched by the fullerene units. This new property resulting from the association of the different molecular subunits allowed detailed investigations of the self-assembly process by means of fluorescence titrations. The binding studies have revealed positive cooperative effects for the assembly of the fullerodendrimers with the ditopic receptor. Interestingly, the stability of the supramolecular 2:1 structures increases as the size of the dendritic unit increases. This positive dendritic effect has been explained by the larger number of possible intramolecular fullerene-fullerene interactions between the two dendritic guests when the number of fullerene subunits is increased.

Synthesis and properties of poly(carbonate‐co‐ester)s obtained by cationic ring‐opening copolymerization of spiroorthocarbonate and ε‐caprolactone

AbstractCationic ring‐opening copolymerization behavior of 1,5,7,11‐tetraoxaspiro[5.5]undecane (SOC1) and ε‐caprolactone (CL), and the thermal behavior of the obtained copolymers are described. When SOC1 and CL were cationically copolymerized under various feed ratios using BF3OEt2 as the initiator in CH2Cl2 at 25 °C, the corresponding copolymers were obtained in 77–99% yields. The 1H NMR spectroscopic analysis of the copolymers revealed that the copolymer compositions were almost identical to the feed ratios, and the diad ratios of SOC1–SOC1/SOC1–CL and CL–SOC1/CL–CL are 48.0/52.0 and 54.3/45.7. These observations proved the random structures of the copolymers without containing the long blocks of the homopolymer sequences. Differential scanning calorimetric (DSC) analysis revealed that the melting points and melting entharpies decreased with the increase of the SOC1 unit compositions, suggesting that the copolymers gain flexibility as the SOC1 unit increases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2937–2942, 2006

Identification of equine cecal bacteria producing amines in an in vitro model of carbohydrate overload.

Acute laminitis has been associated with the overgrowth of gram-positive bacteria within the equine hindgut, causing the release of factor(s) leading to ischemia-reperfusion of the digits. The products of fermentation which trigger acute laminitis are, as yet, unknown; however, vasoactive amines are possible candidates. The objectives of this study were to use an in vitro model of carbohydrate overload to study the change in populations of cecal streptococci and lactobacilli and to establish whether certain species of these bacteria were capable of producing vasoactive amines from amino acids. Cecal contents from 10 horses were divided into aliquots and incubated anaerobically with either corn starch or inulin (fructan; both at 1 g/100 ml). Samples were taken at 6-h intervals over a 24-h period for enumeration of streptococci, lactobacilli, and gram-negative anaerobes by a dilution method onto standard selective growth media. The effects of the antibiotic virginiamycin (1 mg/100 ml) and calcium hydrogen phosphate (CaHPO(4); 0.3 g/100 ml) were also examined. Fermentation of excess carbohydrate was associated with increases in numbers of streptococci and lactobacilli (2- to 3.5-log unit increases; inhibited by virginiamycin) but numbers of gram-negative anaerobes were not significantly affected. A screening agar technique followed by 16S rRNA gene sequence analysis enabled the identification of 26 different bacterial strains capable of producing one or more vasoactive amines. These included members of the species Streptococcus bovis and five different Lactobacillus spp. These data suggest that certain bacteria, whose overgrowth is associated with carbohydrate fermentation, are capable of producing vasoactive amines which may play a role in the pathogenesis of acute laminitis.

Synthesis and properties of copolyesters of p,p′‐bibenzoic acid, dimer acid, and alkylene glycol

AbstractCopolyesters of p,p′‐bibenzoic acid, dimer acid, and an alkylene glycol are prepared by melt polycondensation of of dimethyl p,p′‐bibenzoate, dimer acid, and an alkylene glycol. The copolyesters are characterized by the inherent viscosity, FTIR, proton NMR, DSC, polarized microscopy, and X‐ray diffraction. The polymer composition and sequence distribution of the copolyesters can be seen from the NMR spectra. The copolyesters exhibit a degree of randomness of about 1, indicating that they are random copolymers. The glass‐transition temperature (Tg) and the melting point (Tm) of the copolyesters are found from the DSC heating curves. When the content of the flexible dimer acid unit increases, the Tg of the copolyesters decreases significantly. The copolymerization effect decreases the crystallinity and the Tm of the copolyesters. It can be seen from the DSC, polarized microscopy, and X‐ray diffraction data that some copolyesters derived from 1,6‐hexanediol and 1,5‐pentanediol exhibit a monotropic smectic phase. As the molar content of the dimer acid unit increases, the isotropic–mectic transition temperature and the smectic order decreases significantly. The liquid crystallinity is completely destroyed at certain molar contents of the dimer acid unit. The smectic order of the copolyesters derived from 1,6‐hexanediol is significantly higher than that of the copolyesters derived from 1,5‐pentanediol, and it is described as an odd–even effect. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 750–758, 2003

Breeding success of sympatric dabbling ducks in relation to population density and food resources

Breeding success in sympatric mallard Anas platyrhynchos, teal A. crecca and wigeon A. penelope in a boreal watershed in Finland was studied for 12 years. Benthic and surface‐emerging prey animals were trapped to obtain annual indices of food abundance. Mallard and teal were equally abundant over the years, being roughly twice as numerous as wigeon.Pair density, brood:pair ratio and duckling:pair ratio were used to test the hypothesis that per capita breeding success decreases in a density‐dependent fashion as either pair density or the number of nesting pairs per available food unit increases. In mallard we found no density‐dependent patterns at all. In teal per capita brood production decreased as prey animals became relatively scarcer, but this interpretation may not be robust. In wigeon, however, there were two independent significant patterns of direct density‐dependence in a temporal succession, i.e. between pair density and per capita brood production in the early part of the breeding season, and then between per capita abundance of surface‐emerging insect prey and the number of ducklings per pair. Despite wide dietary overlap and frequent co‐occurrence on single lakes among species in the guild, we found no evidence for interspecific density‐dependent effects. We hypothesize that there is no or infrequent food limitation for breeding dabblers in this system, and that behavior may be the process behind the pattern of density‐dependence in wigeon.

A rare structural characterisation of the phosphomolybdate lacunary anion, [PMo11O39]7−. Crystal structures of the Ln(iii) complexes, (NH4)11[Ln(PMo11O39)2]·16H2O (Ln = CeIII, SmIII, DyIIIor LuIII)

The syntheses and the crystal structures of (NH4)11[LnIII(PMo11O39)2]·16H2O (LnIII = Ce (1), Sm (2), Dy (3) or Lu (4)) are reported in which an LnIII cation is sandwiched between two ‘lacunary’ [PMo11O39]7− anions to give a complex with eight oxygen atoms coordinated to the lanthanide centre in a twisted square antiprismatic geometry. This analogous series of complexes represents only the second time that the [PMo11O39]7− anion has been fully crystallographically characterised. All four compounds are synthesised in high yield and characterised by a range of physical and spectroscopic techniques. 31P NMR, Raman and UV/Vis/nIR spectroscopies give a clear indication that the [LnIII(PMo11O39)2]11− anion is also stable in solution. As LnIII contracts across the lanthanide series the Ln–O bond distances decrease and the splitting of the νP–O vibrational mode within the [PMo11O39]7− unit increases. The relative stability of this species in solution may have importance in elucidating the speciation of Ln(III) and An(III) cations in nuclear waste solutions where phosphopolymolybdate anions are known to form.

Synthesis and non-isothermal crystallization behavior of poly(ethylene-co-1,4-butylene terephthalate)s

A series of random poly(ethylene-co-1,4-butylene terephthalate)s (PEBTs), as well as poly(ethylene terephthalate) (PET) and poly(1,4-butylene terephthalate) (PBT), were synthesized by the bulk polycondensation. Their composition, molecular weight, and thermal properties were determined. All the copolymers are crystallizable, regardless of the compositions, which may originate from both even-atomic-numbered ethylene terephthalate and butylenes terephthalate units that undergo inherently crystallization. Non-isothermal crystallization exotherms were measured over the cooling rate of 2.5–20.0 K/min by calorimetry and then analyzed reasonably by the modified Avrami method rather than the Ozawa method. The results suggest that the primary crystallizations in the copolymers and the homopolymers follow a heterogeneous nucleation and spherulitic growth mechanism. However, when the cooling rate increases and the content of comonomer unit (ethylene glycol or 1,4-butylene glycol) increases, the crystallization behavior still becomes deviated slightly from the prediction of the modified Avrami analysis, which is due to the involvement of secondary crystallization and the formation of relatively low crystallinity. Overall, the crystallization rate is accelerated by increasing cooling rate but still depended on the composition. In addition, the activation energy in the non-isothermal crystallization was estimated.

The adeno-associated virus type 2 Rep protein regulates RNA processing via interaction with the transcription template.

The adeno-associated virus type 2 (AAV) large Rep proteins can act to increase the ratio of spliced to unspliced AAV RNA when they are targeted to the transcription template via a Rep binding element. The required Rep binding site is both location and orientation independent; however, Rep enhancement decreases as the distance between the promoter and the intron of the affected transcription unit increases. Only the AAV intron and an extended polyadenylation site must remain for the AAV transcription unit to manifest responsiveness to Rep. A number of promoters, when driving the AAV capsid gene transcription unit, were responsive to targeted Rep, though to various degrees. Transactivation of transcription initiation is not sufficient for the enhancement of RNA processing, because activation of the P40 transcription unit by other activators targeted to this transcription template did not result in enhancement of the ratio of spliced to unspliced AAV RNA. These results suggest that Rep may act as a trans regulator of RNA processing by modulating such functions coupled to RNA polymerase II (RNA pol II) transcription, perhaps by affecting the composition of the transcription complex either prior to or during elongation. These results reveal another way in which gene expression can be regulated by trans-acting proteins and help explain an important feature of the parvovirus life cycle.

Synthesis and Non-Isothermal Crystallization Characteristics of Poly[(ethylene)-co-(trimethylene terephthalate)

A series of random copolyesters were synthesized by the bulk polycondensation of dimethyl terephthalate with ethylene glycol (EG) and trimethylene glycol (TMG) in various compositions. Their composition, molecular weight, and thermal properties were determined. The copolymers containing 22.2 mol-% ≤ TMG ≥ 46.0 mol-% are crystallizable while the other copolymers containing 32.8 mol-% ≤ TMG ≤ 39.3 mol-% are amorphous. Non-isothermal crystallization exotherms were measured over the cooling rate of 2.5–20.0 K/min by calorimetry and analyzed by the Avrami method. For the crystallization at 2.5 K/min, the Avrami exponent n was estimated to be in the range of 2.91–3.81, depending on the composition. The results suggest that the primary crystallization follows a heterogeneous nucleation and spherulitic growth mechanism. However, when the cooling rate increases and the content of the minor component unit (EG or TMG) increases, the crystallization behavior becomes deviated from the prediction of the Avrami analysis, which is due to the involvement of secondary crystallization and the achievement of relatively low crystallinity. The crystallization rate is accelerated by increasing cooling rate but retarded by incorporating the minor component into the polymer backbone. In addition, the activation energy in the crystallization was estimated.

Changes in Populations of Listeria monocytogenes Inoculated on Packaged Fresh-Cut Vegetables

A variety of Wholesale and retail packaged vegetables and salads were inoculated with a mixture of strains of Listeria monocytogenes and incubated at 4 and 10°C. Whole rutabagas, butternut squash, and onions, as well as packaged Caesar salad, carrots, coleslaw mix, and stir-fry vegetables were purchased from local supermarkets in the Ottawa area. L. monocytogenes population levels remained constant on all fresh-cut vegetables stored at 4°C for 9 days, except for carrots and butternut squash: counts of cell numbers declined on carrots and increased on the butternut squash. Fresh-cut vegetables stored at 10°C, however, supported good growth of L. monocytogenes on all vegetables tested, except for chopped carrots, where the population decreased approximately 2 log units over a 9-day storage period. As in the situation with the produce stored at 4°C, butternut squash supported the highest rate of cell growth. In addition, Caesar salad and coleslaw mix were kept at 25°C for 1 or 2 days before subsequent storage at 4 or 10°C to simulate extreme temperature-abuse conditions. In Caesar salad stored at 4°C, by day 6 an initial 24- and 48-h temperature abuse at 25°C led to a 1.21- and 2.55-log-unit population increase, respectively, over the control. Similar increases were observed on Caesar salads stored at 10°C. Compared to Caesar salad, coleslaw mix temperature-abused at 25°C and then stored at 4°C supported slightly greater increases in the population of L. monocytogenes, i.e., a 3.22- and 3.83-log-unit increase over the control for the 1- and 2-day abused samples, respectively. Coleslaw mix samples temperature-abused and then stored at 10°C, however, only showed log unit increases of 1.75 and 1.94, respectively, compared to the Controls. These results point to the importance of strict temperature control to prevent or reduce the growth of L. monocytogenes cells on fresh-cut vegetables.

New luminescent polymers for leds and LECS

AbstractStatistical copolymers 5 containing poly(2‐dimethyloctylsilyl‐1,4‐phenylenevinylene) (DMOS‐PPV) and poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) have been synthesized using the dehydrohalogenation condensation route. The copolymers show a shift of photoluminescence maxima to longer wavelengths as the proportion of the MEH‐PV unit increases. This trend is accompanied by reduced efficiencies and lower turn‐on voltages in single layer electroluminescent devices. Light‐emitting electrochemical cells (LECs) have been prepared using a blend of DMOS‐PPV 1 with poly(ethylene oxide)/lithium triflate and the homopolymer poly[2‐methoxy‐5‐(triethoxymethoxy)‐1,4‐phenylene vinylene] (MTEM‐PPV) 9 with lithium triflate. In comparison with single‐layer devices which were fabricated using the homopolymers 1 and poly[2,5‐bis(triethoxymethoxy)‐1,4‐phenylene vinylene] (BTEM‐PPV) 10, the LEC devices showed lower turn‐on voltages.

Synthesis and properties of poly(alkylenep,p?-bibenzoate-co-adipate)s

Various poly( alkylene p,p '-bibenzoate-co-adipate )s were prepared by melt polycondensation of dimethyl-p,p '-bibenzoate, adipic acid, and an alkylene glycol. The copolyesters were characterized by inherent viscosity, FTIR, proton NMR, DSC, polarized microscopy, and X-ray diffraction. The polymer composition and sequence distribution of the copolyesters can be seen from NMR spectra. The copolyesters exhibit a degree of randomness of about 1, indicating that they are random copolymers. From the DSC data, the glass transition temperature (T g ) and melting point (T m ) of the copolyesters can be detected. When the content of the flexible adipate unit increases, the T g of copolyesters decreases significantly. The type of alkylene glycol used also affects the T g to some extent. The copolymerization effect decreases crystallinity and the T m of the copolyesters. The DSC, polarized microscopy, and X-ray diffraction data show that some copolyesters derived from 1,6-hexanediol exhibit a monotropic smectic phase. As the molar fraction of adipate unit in diacid units, x, is more than 0.4, the liquid crystallinity is completely destroyed.

Group living for elderly patients with dementia — A cost analysis

The average labour cost of group living for elderly people suffering from senile dementia amounted to just over SEK 230 000 per patient and year, or SEK 639 per patient and day (24 h), in 1992 prices. These figures emerge from our study of 106 group-living units in 46 municipalities in southern Sweden. The average staff density, that is the number of full-time employees on a yearly basis, was 1.06 per patient. The study also shows that the labour cost per patient decreases when the number of patients in a unit increases. Units that form part of other types of residence for the elderly have lower labour costs than detached group-living units (everything else being equal). If individual flats or apartments are large (at least two rooms), a higher staff density was observed. A high degree of functional disability in the individual entails higher staff density and consequently higher labour costs as well. However, in comparison with other forms of caring for the elderly, such disabilities have a less marked effect on labour costs. Everything else being equal, comparatively young residents entail higher labour costs than older ones. The average cost per patient in group-living units amounted to SEK 986 per day. this cost includes the cost of care (labour cost adjusted for flexible salary increments), as well as of capital, operation and maintenance, and food (raw materials). The cost of care amounts to approx. 80% of the estimated cost per patient. The average cost per patient is higher in group-living units than in old people's homes; but as regards dementia sufferers with some degree of functional disability, the cost of care is probably about the same in both types of accommodation.

Synthesis of Poly(2-methoxy-5-methyl-1,4-phenylenevinylene) and Its Poly(1,4-phenylenevinylene) Copolymers: Electrical and Third-Order Nonlinear Optical Properties

Asymmetrically disubstituted poly(2-methoxy-5-methyl-1,4-phenylenevinylene) (PMMPV) and a series of poly(1,4-phenylenevinylene-co-2-methoxy-5-methyl-1,4-phenylenevinylene)s (poly(PV-co-MMPV)) were synthesized through a water-soluble precursor route. These polymers were characterized using UV-visible, FT-IR spectroscopy, and a DSC, TGA thermal analyzer. The electrical conductivities of the polymers were investigated by the four-in-line method at room temperature. A PMMPV film can be stretched up to 5 times and doped with FeCl 3 and I 2 to give electrical conductivities of 27 and 7.4 S/cm, respectively, along the drawn direction. In copolymers, as the content of the MMPV unit increases, the electrical conductivity steadily increases. The X (3) (-3ω ; ω, ω, ω) value of PMMPV was determined by the third harmonic generation (THG) technique at 1907 nm, the fundamental wavelength. The measured X (3) value was 7.5 x 10 -12 esu.

Use of gas-turbine engines in oil field pumping units

Modern oil field pumping units for hydraulic fracturing of formations, in particular deep-penetration fracturing, typically have high power outputs. The unit, which is mounted on a truck chassis, consists of an engine, transmission, primary actuating mechanism (high-pressure pump), manifold, and other equipment. Diesels with power of 700-1500 kW are used as the drive engine for these units; the operating indexes of diesels vary sharply with load, dropping off when the load is increased only slightly. Pumping units do not operate under steady conditions. The injection pressure for pumping units will depend on the formation pressure, the physical properties of the formation, the well depth, the diameter of the well string through which the fracturing fluid and the sand mix are pumped, the fluid delivery rate, and so on. At the start of the operation, as the fracturing fluid and the sand mix are pumped, the fluid delivery rate, and so on. At the start of the operation, as the fracturing fluid is injected, the pressure on the pumping unit increases. Then, at the moment of fracturing the formation, the pressure drops off sharply and will vary, depending on the hydraulic resistances to movement of the sand mix and injection fluidmore » in the pipe and in the bottom-hole zone of the formation. Gas-turbine engines with a free turbine are more effective as the drive for pumping units. The first attempt to use a gas-turbine engine was made in the mid-1960s. At that time, however, the work was limited to the development of a rough design, in view of the great length of the AI-23 engine and, most important, its cost. In recent years, free-turbine gas engines have been designed and manufactured commercially as the drive for transport vehicles. The characteristics of these engines match the requirements for use in pumping units. Gas-turbine engines have the advantages over diesels. These advantages are discussed.« less

Radiolytic crosslinking and chain scission in aliphatic and alkyl-aromatic polyamides—II

Regression analysis of the radiation parameters of nine aliphatic polyamides exposed to ionizing radiation leads to the conclusion that the decline in the ratio of chain scission to crosslinking in higher aliphatic polyamides is best related to the linear increase in the methylene content of, or the number of methylene groups in, the polyamide repeat unit. G(crosslink) [ G(X)] and G(chain scission) [ G(CS)] values, however, do not correlate well with either of these parameters. Rather it is found that the major determinant of yields [about 80–85% of the variation for G(X), 70% for G(CS)] is the number of hydrogen atoms or methylene groups in the amine residue. A minor determinant [15% of the variation for G(X) and 30% for G(CS)] is the number of hydrogen atoms or methylene groups in the acid residue of the repeat unit. Significantly, although there was little sign of a decrease in G(CS) in the higher aliphatic homologues (up to 11 methylene residues per amide group), G(CS) is found to be positively related to the number of methylene groups in the amine residue but negatively related to the number of methylene groups in the acid residue. Thus although the amine residue dominates the radiolytic response, the acid residue plays a critical if lesser role in determining chain scission yields in polyamides. Thus a polyamide with the repeat unit —(CH 2) 3 n CONH(CH 2) n NHCO— would be predicted to have a very low or zero G(CS) and, if n is 10 or more, a G(X) comparable to that of polyethylene. Although, logically, the yields of crosslinks and chain scissions in polyamides would be expected to tend to that of polyethylene as the number of methylene groups in the repeat unit increases, use of two models assuming an exponential trend to the G(X) value characteristic of polyethylene in the analysis did not provide better fits to the data than the simple linear model referred to above. Indeed, the assumption of a significant exponential trend factor led to a marked drop in the goodness of fit.

Shortening of feet in longer articulatory units

A 20‐min radio broadcast of a short story, digitized and measured for both syllable and pause durations, was studied with respect to the durational characteristics of both pause durations and rhythmic groups. Syllables were grouped into feet and foot durations were calculated. Feet were then grouped into interpausal units and the durations of these larger articulation groups were also calculated. The hypothesis that pause duration is a function of average foot length, determined over the previous n feet, was tested for different values but no supporting evidence was found. It has already been shown that the durations of both stressed and unstressed syllables in a foot tend to decrease as the number of syllables in the foot increases. Evidence was found here for a similar shortening of average foot durations as the number of feet per interpausal unit increases. This shortening indicates that an element of planning may be involved at higher articulatory levels. That the shortening is asymptotic lends support to the concept of a minimum duration at some level of the timing hierarchy.

Interactive Computer Graphics System Improves Planning of Directionally Drilled Wells in the East Wilmington Field

Summary The Long Beach Unit of the East Wilmington field contains more than 1,200 wells directionally drilled from four manmade islands and five land-based drilling sites. Planning new wells that avoid interference with existing wells becomes more difficult and time-consuming as the density of wells in the Unit increases. Improvements and modifications in design procedures have culminated in the interactive computer graphics system now in use. The interactive computer graphics system (ICGS) permits the viewing of a proposed new well or redrill well course, together with all existing well surveys and other proposed well courses in the area of interest. Plan, section, and traveling cylinder views can be displayed to allow the identification of design problems. The significance of the problems is then minimized by use of the interactive features of the system to refine the design parameters. The system's interactive features are also used to create, edit, and plot the finalized design. Reductions in design and drilling costs and many other less-direct benefits have been realized as a result of the system's use. The step-by-step use of the system from the user's point of view is described and examples of its graphic output are presented. To the best of our knowledge, this is the most advanced system of its kind in use today.

Conditions for starting electric pump unit

The conditions for starting water-immersible electric pumps depend on many factors~ viz., the depth of immersion of the pump into the well, the water level in the well, the state of the delivery pipe, the motor power, the power and voltage in the terminals of the power source, its load, the length and cross section of the electric wires, and many others. The starting conditions become more complicated as the capacity of the unit increases. In view of this, for fabricating the first ETsV 12-63-520 electric pumps with an immersion depth greater than 500 m we studied, taking account of the potentials of the experimental station, the conditions for starting the unit as a function of the voltage in the motor terminals, the length of the electric wire and its location, the location of the gate valve in the pump delivery line.

The estimation of complete aggregation structures

The object of this paper is to establish several results which permit efficient estimation of behavioral parameters in models of aggregate data. The approach follows the ‘minimum chi-square’ estimation strategy customarily applied to contingency tables; by treating aggregates as general functionals of empirical distribution functions for each ‘cell’ (i.e., aggregation unit), consistent and asymptotically normal estimates are obtained for a fixed number of aggregation units as the number of observations per unit increases. The paper also discusses conditions under which the proposed estimators are asymptotically efficient, and gives examples applying the approach to continuous and discrete demand models.