Search results for "strength"

Macromolecules in ordered media VIII. High-performance size-exclusion chromatography as a technique for characterizing the interaction between polyan…

1997

Abstract The association of polyanions with liposomes based on dimyristoyl phosphatidyl choline and stearylamine at a ratio of 50:50 was investigated in terms of the binding model and, to a lesser extent, of the partition model. Aqueous size-exclusion chromatography has been proposed as a major technique for monitoring the interactions between liposomes and polyelectrolytes and the results were compared with those obtained by fluorescence spectroscopy. Quantitatively, the extent of the association follows the order: Sodium poly(styrene sulfonate) ( K A = 10 000 M −1 ), poly (acrylic acid) ( K A = 2000 M −1 ) and poly ( l -glutamic acid) ( K A = 700 M −1 ). Also, the effect of the ionic stre…

Macromolecules in ordered media: 7. Influence of ionic strength and bilayer composition on the association of polyelectrolytes to mixed liposomes

1997

The effect of both the phospholipid composition of the bilayer and the ionic strength of the medium on the association between poly(2-vinyl pyridine) and mixed liposomes based on dimyristoyl phosphatidic acid and dimyristoyl phosphatidil choline was investigated using fluorescence spectroscopy. Intensity changes upon addition of vesicles have allowed us to estimate the extent of the association and data have been processed as association isotherms. We found that the association is enhanced by increasing both the ionic strength and the anionic phospholipid fraction. However, whereas the negative net charge of the bilayer strongly enhances the interaction, the presence of more and more electr…

Thermal nucleation of cavities in liquid helium at negative pressures

1993

We have investigated the nucleation rate at which cavities are formed in $^{4}\mathrm{He}$ and $^{3}\mathrm{He}$ at negative pressures due to thermal fluctuations. To this end, we have used a density functional that reproduces the He liquid-gas interface along the coexistence line. The inclusion of thermal effects in the calculation of the barrier against nucleation results in a sizable decrease of the absolute value of the tensile strength above 1.5 K.

Characterization and thermomechanical assessment of a SiC-sandwich material for Flow Channel Inserts in DCLL blankets

2019

Abstract Flow Channel Inserts (FCIs) are key elements in the high-temperature Dual Coolant Lead Lithium (DCLL) blanket, since they insulate electrically the flowing PbLi to avoid MHD effects and protect the steel structure from the hot liquid metal. SiC-based materials are main candidates for high-temperature FCIs, being a dense-porous SiC-based sandwich material an attractive option. The present work is focused on the development of such a SiC-based material. On the one hand, in order to assess the suitability of the concept for FCIs, the main results of a stress analysis, MHD and heat transfer simulations are summarized. On the other hand, the experimental production of the SiC-based mate…

Flexural behavior of external beam-column reinforced concrete assemblages externally strengthened with steel cages

2016

In this paper, an experimental study referring to the flexural behavior of full-scale external beam-column joints externally strengthened with steel angles and strips and subjected to cyclic reversal loading is presented. One control specimen and five other specimens having the same characteristics as the control specimen but strengthened with steel angles and strips along beams and columns, and characterized by different configurations of strengthening in the critical regions, were tested. The control specimen was designed with a weak column and strong beam to reproduce the most common cases of old frame structures in the Mediterranean area, which were designed only for gravity loads and a…

Mechanical properties of blends of low density polyethylene with isotactic polypropylene II. effect of mixing temperature and rate

1989

Abstract The effects of mixing temperature and rate on tensile properties of some blends of low density polyethylene with isotactic polypropylene have been studied. Results, with those presented previously on the effect of mixing time, indicate significant effects of mixing parameters and suggest the need to find an “optimum mixing procedure” for each kind of blend.

1997

Polyethylene wastes (low-density polyethylene, high-density polyethylene and their binary blends) were subjected to high-energy radiation, using a 60Co gamma radiation source. The crosslinked materials thus obtained were processed to heatshrinkable films. Tensile strength could be sharply improved by increasing the dose up to 20 Mrad, simultaneously increasing the elongation at break of the most degraded PE waste. An increase of the degree of compatibility of LDPE and HDPE waste was also observed. All samples examined exhibit a “memory effect” after drawing at 130°C and cooling under tension followed by further heating under relaxed conditions. The value of shrinkage depended on the degree …

Trunk Muscle Strength After Lumbar Spine Fusion: A 12-Month Follow-up.

2019

Objective: The aim of this study was to investigate changes in trunk muscle strength 12 months after lumbar spine fusion (LSF) compared to preoperative strength. Methods: A total of 194 patients (mean ± standard deviation [SD] age, 61 ± 21 years) who underwent LSF participated in this prospective longitudinal study. Physical measurements of the participants were made before surgery and 12 months postoperatively. Isometric trunk extension and flexion strength was measured using a strain-gauge dynamometer in the standing position. Strength changes were calculated. Regression analysis was performed to explore which factors predicted strength levels at 12 months postoperatively. Results: The pr…

Helium-3 imaging of pulmonary ventilation.

1998

In the first studies in humans, the 3He gas was Helium is an inert, non-radioactive, noble gas. directly inhaled from the glass cell or via a mouth 3He is a rare isotope with a nuclear spin c. As it tip or plastic bag [2, 3]. The estimated inhaled is derived from tritium decay, it is quite expensive. volume in our studies was 400–500 ml. Recently, Non-polarized 3He costs 100–150 US$. Advanwe developed a computer-assisted application tages for applications in humans are: negligible system which is compatible with spontaneous solubility in water or blood, no adverse effects — breathing, assisted or mechanical ventilation. The widely used in deep-sea diving (80% He, 20% lungs can be flushed wi…

Handgrip strength and cause-specific and total mortality in older disabled women: exploring the mechanism.

2003

OBJECTIVES: To examine the association between muscle strength and total and cause-specific mortality and the plausible contributing factors to this association, such as presence of diseases commonly underlying mortality, inflammation, nutritional deficiency, physical inactivity, smoking, and depression. DESIGN: Prospective population-based cohort study with mortality surveillance over 5 years. SETTING: Elderly women residing in the eastern half of Baltimore, Maryland, and part of Baltimore County. PARTICIPANTS: Nine hundred nineteen moderately to severely disabled women aged 65 to 101 who participated in handgrip strength testing at baseline as part of the Women's Health and Aging Study. M…