Using Kelgin to Increase Heat Resistance and Strength of the Sheet of Paper Against Prolonged Heating

The purpose of this paper has been to examine what properties of sheet strength may be stabilized by the use of kelgin in a size press application and after a subsequent heating period. A softwood kraft pulp was used because of the strength properties which it possesses. Alkaline sizing with Aquapel and Kymene was felt to be the best because of the alkaline p.H. range which was desired. The sheets were sized with solutions of Kelgin (M .V.) of varying concentrations and treated at 150 and 175 °C. The effects were studied using the M.I .T. Fold Test, the Instron Tensile (kg to rupture), and the Instron Elongation. The results showed that as the concentrations of the kelgin size solutions increased, some protection was afforded the fiber against prolonged heating. The strength loss was appreciable in the samples which were treated at the different temperatures. The room temperature samples showed higher strength properties than either of the samples heated at 150 or 175°C. which was as expected. It was shown that the high viscosity of the kelgin solutions at the concentrations of 1.00 and 1.25 percent tended to . give a tapering off of the protection which was expected. A viscosity reducer (Azite 900 Liquifier) was used in conjunction with the kelgin solutions to study the effects of a reduced viscosity on strength maintenance. It was shown that the liquefier did indeed increase the penetration of the kelgin into the sheet and provide a better protection. The experimental findings demonstrate that the use of kelgin in the form of a sizing solution can give beneficial results against loss of strength upon prolonged heating. It was also shown that the magnitude of this effect was not as great as had been expected from previous findings

MULTIPLE COMPARISONS WITH THE BEST: BAYESIAN PRECISION MEASURES OF EFFICIENCY RANKINGS

A large literature exists on measuring the allocative and technical efficiency of a set of firms. A segment of this literature uses data envelopment analysis (DEA), creating relative efficiency rankings that are nonstochastic and thus cannot be evaluated according to the precision of the rankings. A parallel literature uses econometric techniques to estimate stochastic production frontiers or distance functions, providing at least the possibility of computing the precision of the resulting efficiency rankings. Recently, Horrace and Schmidt (2000) have applied sampling theoretic statistical techniques known as multiple comparisons with control (MCC) and multiple comparisons with the best (MCB) to the issue of measuring the precision of efficiency rankings. This paper offers a Bayesian multiple comparison alternative that we argue is simpler to implement, gives the researcher increased exibility over the type of comparison made, and provides greater, and more in-tuitive, information content. We demonstrate this method on technical efficiency rankings of a set of U.S. electric generating firms derived within a distance function framework.Research Methods/ Statistical Methods,

RESPONSE OF WARM SEASON TURFGRASSES TO REDUCED LIGHT ENVIRONMENTS

Shade or low light tolerance is an increasingly important issue to turf managers as they are often expected to grow turf in less than ideal agronomic conditions. As permanent structures such as residential buildings add to already problematic shade caused by trees, and other barriers, new solutions are needed to help turf managers provide acceptable turf conditions. The plant growth regulator trinexapac-ethyl (TE) can lessen negative responses of turfgrass to shade. Two experiments were conducted during the summers of 2008 and 2009 to evaluate various grasses under a reduced light environment (RLE). In the first study, performance of `Diamond\u27 zoysiagrass in a RLE was evaluated when maintained under putting green conditions. In a second study, performance of various cultivars of zoysiagrass [Zoysia japonica Steud.] [Zoysia matrella (L.) Merr.] and bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy] were evaluated under a RLE. Both studies included three levels of shade: (0, 60, and 90%) and two levels of trinexapac-ethyl (0 and 0.57 kg ai ha-1 wk-1 Primo MAXX 1 EC). TE treatments were applied with a CO2 backpack operating at 189.5 L ha-1 (20 GPA) with an 8003 flat flan nozzle. Application of shade was initiated on 23 May 2008 and removed 30 October 2008. In 2009 application of shade was initiated 24 May and removed 31 October. Plot size in the first study was 2m by 1.5m. Shade structures were maintained at a height of 45 cm above ground level to maintain proper airflow. Shade tents were removed 2 hours weekly to take measurements and perform maintenance. In the first study, application of Trinexapac-ethyl to 90% shade increased turf quality by ~4 units from 1 to ~5 at the end of each study year. While still not commercially acceptable (TQ≥7), some turf cover was still preserved. Other plant responses measured included percent lateral regrowth (LR), total non-structural carbohydrates (TNC), clipping yield, ball roll distance, and total shoot chlorophyll. Lateral regrowth increased initially with shade application until plant health declined, leading to decreased LR. Application of TE decreased LR by limiting plant growth. Total non-structural carbohydrates decreased with increasing shade application, and increased with TE application. Clipping yield initially increase in both 60% and 90% RLE, then declined as plant health declined. Application of TE slowed clipping yield production at the beginning of the study, then increased clipping yield at the end due to increase in plant health from TE application compared to treatments not receiving TE. Ball roll distance was decreased by 60% and 90% RLE initially. As plant health in 90% RLE without TE and 90% RLE + TE declined, ball roll distance increased due to declining turf cover. Chlorophyll concentration was increased by both 60% RLE with and without TE. Ninety percent RLE with and without TE reduced chlorophyll concentration. In the second study, TQ decreased with increasing RLE level in all cultivars. At the end of both years, Diamond and Meyer zoysiagrass demonstrated the highest TQ in a 60% RLE out of all cultivars. In a 90% RLE, Meyer zoysiagrass demonstrated the highest TQ at the end of each year. Application of TE increased TQ of cultivars grown in 60% and 90% RLE. At the end of 2009, Meyer zoysiagrass + TE application was the only cultivar to maintain turf cover in a 90% RLE. Clipping yield was initially increased in all cultivars by increased levels of RLE. Application of TE decreased clipping yield. As plant health declined, clipping yield also decreased. At the end of the study, TE application increased clipping yield as a result of increased plant health. Initially, an increase was seen in chlorophyll concentration with increased levels of RLE. Application of TE to RLE treatments further increased chlorophyll concentration. At the end of each study, chlorophyll concentration decreased in 60% and 90% RLE treatments as plant health declined. Once again, as TE application increased plant health, chlorophyll concentration was increased

Biology, Ecology, and Control of Doveweed (Murdannia nudiflora [L.] Brenan)

Doveweed (Murdannia nudiflora [L.] Brenan) is a summer annual in the Southeastern United States with an expanding geographic range. The light green color and texture of doveweed is problematic for turfgrass managers as it contrasts with the color and texture of desirable turfgrasses. Limited research is available concerning the biology, ecology, and herbicide control options for doveweed. Therefore, experiments were conducted to improve the understanding of how environmental conditions effect doveweed germination, how cultural practices and environmental resource availability effect doveweed growth and development, to identify pre- and postemergence herbicides with efficacy for doveweed control, and to improve the understanding of why poor control is observed with postemergence herbicides. Doveweed germination was affected by scarification, osmotic potential and salt concentration. Mechanical abrasion of the seed coat increased germination to 84% compared to 18% in non-scarified seed. Germination was similar between osmotic potentials of 0 and -0.4 MPa and was reduced ~50% in a -0.8 MPa solution, suggesting doveweed favors a moist environment for germination. Germination was similar between NaCl concentrations of 0 and 40 mM, and reduced ~50% in a 160 mM NaCl solution, suggesting infestations can occur in moderately saline soils. Germination was not affected by nitrate concentration or pH. Doveweed spread of established plants was between 30 and 46% less in response to low mowing after one study year; however, differences in doveweed spread were not detected after year two. The lack of mowing height effect was attributed to recruitment of doveweed seedlings from seeds produced at the end of year one. This result suggests doveweed infestations can rapidly increase in severity if left unchecked. When grown in competition with `Tifway\u27 bermudagrass (Cynodon dactylon [L.] Pers × C. transvaalensis Burtt-Davy), doveweed coverage per plant was ~38% less when mown at 1.32 cm compared to mowing at 2.65 cm. In the same study, increasing nitrogen rate from 24.5 to 49 kg N ha-1 increased doveweed spread per plant 75%. In response to a reduced light environment (RLE), shoot production did not increase on a weight basis; however, an etiolation response was detected as internode length increased 28% in plants grown in a 30% RLE and 39% in a 50 and 70% RLE. Root production on a weight basis was between 46 and 59% less in all RLE treatments compared to full sunlight treatments. Doveweed shoot growth was significantly greater in plants maintained above 50% field capacity (FC) and plants maintained at ≥75% FC produced more root biomass than 50, 25, and 12.5% FC treatments, further suggesting doveweed suggests a moist environment for growth and development. Sequential applications of pre- and postemergence herbicides improved doveweed control compared to single applications. Indaziflam, dimethenamid-p, and oxadiazon applied at 0.054, 1.68, and 3.36 kg ai ha-1, respectively, provided ~12, 6, and 6 wk of doveweed control, respectively, when applied on May 1 in Augusta, GA. Postemergence control was greatest following sequential application of sulfentrazone + metsulfuron at 0.30 kg ai ha-1, thiencarbazone + iodosulfuron + dicamba at 0.176 kg ai ha-1, 2,4-D + MCPP + dicamba + carfentrazone at 0.123 kg ai ha-1, or thiencarbazone + foramsulfuron + halosulfuron at 0.136 kg ai ha-1 21 days apart

Stroke, High Blood Pressure and The Renin–Angiotensin–Aldosterone System – New Developments

This review considers whether a case can be made for a protective effect of inhibitors and blockers of the renin–angiotensin–aldosterone system (RAAS) on the cerebral circulation. It first looks at whether there exists a preferential effect on the cerebral circulation during a drug-induced lowering of high arterial blood pressure and cardiovascular morbi-mortality. It then goes on to consider background studies on the relationship between inhibition of the RAAS and stroke. This is followed by exploration of possible new directions in the inhibition of the RAAS and its effect on stroke

α-Tocopherol is well designed to protect polyunsaturated fatty acids

poster abstractPolyunsaturated fatty acids (PUFA) are an influential constituent in cell membranes, but are extremely vulnerable to oxidation. The presumptive role for α-tocopherol (α-toc), the molecular form of vitamin E retained by the human body, is to protect PUFA-containing lipids from oxidation. To investigate whether α-toc preferentially interacts with PUFA in support of this function, we performed MD simulations on lipid bilayers composed of 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22-6PC) and 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) in the presence of α-toc. SDPC with docosahexaenoic acid (DHA) for the sn-2 chain is polyunsaturated, while SOPC with oleic acid (OA) for the sn-2 chain serves as a monounsaturated control. The simulations were run at 37 °C under constant pressure for 200 ns on a system that comprised 80 phospholipid molecules, 20 α-toc molecules and 2165 water molecules. In qualitative agreement with our results from solid state 2H NMR and neutron scattering experiments, the simulations show that α-toc increases order inside the bilayer and that the chromanol headgroup sits near the surface in both SDPC and SOPC. Analyses of the density distribution of the lipid chains relative to α-toc show that the α-toc’s chromanol headgroup, the part of the molecule that protects against oxidation, would have more chance to interact with PUFA chains than saturated chains. A major prediction from our simulations is that α-toc undergoes flip-flop across the bilayer and that the rate is an order of magnitude greater in SDPC than SOPC. This is a remarkable finding that reveals a possible mechanism by which the chromanol group would not only wait at the membrane surface but would also patrol the membrane interior to meet lipid radicals and terminate the chain reaction by which lipid peroxidation proceeds

The Relationship Among Absorption Anxiety and Frontal Electromyogram

This study examined the relationship among absorption, anxiety (state and trait), and frontal EMG in a sample of sixty undergraduate students. These relationships were examined during a baseline (relaxation) condition and during an anxiety condition during which an extemporaneous speech was given. It was determined that absorption was inversely related to state anxiety and trait anxiety was directly related to state anxiety measured after the relaxation period. Absorption and/or trait anxiety were not related to state anxiety after the speech anxiety condition. There was no relationship between absorption or trait anxiety and frontal EMG during either condition. In addition, state anxiety and absorption were inversely related at baseline. Implications of these results and directions for future research are presented

Synthesis and Properties of Poly(α-hydroxy acid)s with Poly(ether) Cores

Novel biomaterials composed of a polyglycidol backbone with polyester branches consisting of poly(lactide) or poly(lactide-co-glycolide) are synthesized and characterized. Thermal stability, mechanical properties, and hydrolytic degradation of these polymers are essential factors of their processing and practical application. Data from the analysis of the polymer properties is used to determine structure-property relationships for the branched polyesters. Poly(glycidol) (PG), poly(glycidol)-g-L-lactide (PG-g-La), and poly(glycidol)-g-glycolide (PG-g-Gly) are synthesized for evaluation of the core material and simple branched systems. Thermogravimetry, Fourier transform infrared spectroscopy, and isoconversional kinetic analysis are used to evaluate the kinetic and mechanistic aspects of nonoxidative thermal degradation. It is found that PG degrades in a single mass loss step, whereas, PG-g-La and PG-g-Gly degrade in two. It is demonstrated that the first step in degradation of PG-g-La and PG-g-Gly is associated with decomposition of the pendant groups and the second is due to degradation of the PG backbone. Poly(lactide)s and poly(lactide-co-glycolide)s with different number of arms are synthesized from L-lactide and glycolide monomers using stannous (II) 2-ethylhexanoate and alcohols containing 1, 2, 25 and 51 hydroxyl groups. 1-dodecanol is used to produce the 1-arm polymer, poly(ethylene glycol) for the 2-arm polymer, and polyglycidols of appropriate molecular weight are used to initiate the 25- and 51-arm branched polyesters. Polymer composition and molecular weight are characterized by 1H NMR and gel permeation chromatography (GPC). Thermal properties of the polymers are studied using differential scanning calorimetry (DSC). Thermal degradation behavior is investigated using a combination of thermogravimetry, FTIR spectroscopy, and isoconversional kinetic analysis. Polymer processing and use are evaluated by melt rheology, dynamic mechanical analysis (DMA), and in vitro degradation. Melt rheology demonstrates branched polymers have favorable processing temperatures. DMA demonstrates melt-processed polymer samples have similar storage and loss modulus values at room temperature and body temperature. Hydrolytic degradation and erosion is investigated in phosphate buffer pH 7.4 at 37 °C for 28 days. Degraded samples are analyzed by gravimetry, DSC, dilute solution viscometry (Cannon-Fenske), and GPC