Degree Of Dilution Research Articles

What is the therapeutically active ingredient of homeopathic potencies ?

The nature of the ‘active ingredient’, in homeopathic high dilutions is investigated. A model for every degree of dilution is introduced; within this the active ingredient can be dealt with in physical terms. In mathematical terms this model has features which correspond to the axioms of weak quantum theory. Features which are similar to entanglement in ordinary quantum theory are discussed in particular.

Multiaxial deformations of end-linked poly(dimethylsiloxane) networks. 4. Further assessment of the slip-link model for chain-entanglement effect on rubber elasticity

The Edwards–Vilgis slip-link model for the chain-entanglement effect on rubber elasticity is critically assessed on the basis of quasiequilibrium biaxial stress—strain data of end-linked polydimethylsiloxane (PDMS) networks with different entanglement densities. The PDMS networks with different entanglement densities were prepared by end-linking end-reactive long precursor PDMS in solutions with different solvent contents. The slip-link model, in which trapped entanglement is modeled by fictitious mobile slip-link attaching two entangled chains, satisfactorily describes the biaxial data over the entire range of deformation for all the networks examined. The model-specific parameters, i.e., slippage of slip-link (η) and inextensibility of network (α), were employed as adjustable parameters in data-fitting. The fitted values of η and α vary reasonably with the degree of dilution at network preparation, i.e., entanglement density. With an increase in dilution, i.e., decrease in entanglement density, η increases, whereas α decreases. In addition, the fitted values of η and α are in good agreement with the estimates from another molecular approach independent of mechanical testings: η=Me/Mc, where Me and Mc are the molecular masses between neighboring entanglements and between adjacent cross-links, respectively; α=nj−1/2, where nj is the number of Kuhn segments between adjacent elastically effective junctions including cross-links and trapped entanglements. The satisfactory data-fit with the model parameters of physically reasonable magnitudes supports the validity of the slip-link model for entanglement effects on rubber elasticity.

Electric properties of apple purée and pulpy apple juices

Results are presented of research, the aim of which has been to determine the selected physicochemical qualities, including electric quantities, of apple purees and pulpy juices obtained from them. The characteristics of the electric properties have covered the measurements of impedance (Z) and effective resistance (R), admittance (Y) and conductance (G), as well as equivalent parallel capacitance (Cp) and equivalent series capacitance (Cs). Changes have been determined in the puree properties relating to the technology of production as well as the function of diluting and the storage period. Apple purees, depending on the production technology, are characterized by the diversified, characteristic ranges of the resistivity and conductivity values. As the degree of the puree dilution rises, conductivity of juices falls. These relationships remain true throughout the puree storage period. In the conditions of the experiment, the measured values of resistivity and conductivity of pulpy juices clearly determine the content of apple purees in juices.

Linear rheology of multiarm star polymers diluted with short linear chains

We present experimental results on the linear rheology of multiarm star/linear polymer mixtures, the latter having molecular weight much smaller than the star arm molecular weight. In such a case the linear chains act as ideal macromolecular solvents, which dilute entanglements of the arms. Using different star polymers we show that it is possible to account for this dilution and describe the linear rheology of the mixtures using the Milner–McLeish theory for arm relaxation, complemented by the longitudinal modes of stress relaxation and high frequency Rouse modes. A universal description of the isofrictional arm relaxation time as a function of the number of entanglements is obtained for stars of any functionality and degree of dilution. The slow structural mode, related to the diluted star’s colloidal core, also depends on the number of entanglements, but in a more complex way.

Odor Concentration Decay and Stability in Gas Sampling Bags

This paper presents results of an experimental study into factors contributing to decay of odor samples during storage, between 4 and 40 hr after sample collection. The odor studied was sampled from a tobacco processing plant as part of collaborative research with a view to establishing a manual outlining methods for odor annoyance management, specifically for the tobacco industry. In August and September 1997, an experimental program was carried out in which two types of tobacco odor were sampled: Burley Toaster and Mix. The dependent variable was odor concentration in the bag, measured by dynamic olfactometry in accordance with the draft Comité Européen de Normalisation (CEN) standard EN13725 “Air Quality— Determination of Odor Concentration by Dynamic Olfactometry.” The independent variables were sampling bag material, degree of dilution during sampling, dilution gas used, particle removal during sampling, and age of sample in hours. In the first phase, 94 odor analyses were carried out. In a second test, 32 samples were analyzed for odor concentration. In addition, 16 samples were analyzed using gas chromatography-mass spectrometry (GC-MS). Analysis of the results (analysis of variance) led to the unexpected conclusion that Nalophan film bags performed significantly better than metalized Cali-Bond layered film as a bag material. The odor concentration of samples in Nalophan bags remained relatively stable between 4 and 12 hr after sampling. After 30 hr, decay to about half the initial concentration, as measured at 4 hr, was observed. Particle removal during sampling caused the odor concentration in the bags to be reduced by approximately 20%. For practical reasons, particle removal remains useful, to avoid contamination of equipment. Using air or nitrogen as the neutral gas for pre-dilution during sampling or the dilution factor used (between factor 2 and 6) did not appear to have an effect on the decay characteristic of odor samples. The following recommendations are suggested for the practice of collecting odor samples and apply specifically to tobacco processing emissions: • Analyze samples as soon as possible, preferably within 12 hr; • When samples age for more than 12 hr, decay is likely to cause a reduction in odor concentration to half the original concentration at age 30 hr; • Use sampling bags made of Nalophan NA or benchmark performance of other materials against Nalophan NA before using alternative materials; • Use pre-dilution when sampling only for the purpose of avoiding condensation during sample storage. Use an appropriate minimum dilution factor to avoid condensation; • Both nitrogen and high-purity (synthetic) air are suitable to use as neutral gas for pre-dilution; and • When sampling tobacco odors, use an odorless filter to remove particles. This practice removes a source of variation and avoids contamination of equipment. The effect on results, despite being consistently lower in odor concentration, is not meaningful in terms of perceived intensity or annoyance potential.

Selection of spectral lines of a CW chemical HF laser

The spectral distribution of laser radiation power generated in two (initial and final) regions of the flow of an active medium formed by a three-jet nozzle array of a supersonic cw chemical HF laser embodying the nozzle-nozzle-nozzle mixing scheme is investigated experimentally. It is demonstrated that the spectral lines can be selected by merely varying laser operating parameters, such as the feedback factor of the cavity, the orientation of the optical axis of the cavity with respect to the exit plane of the nozzle array, and the degree of secondary dilution of the active medium with helium. This method results in the selection of one line P1−0 (6) with a power as high as 80% of the total radiation power and two lines P1−0 (5) and P1−0 (6) with a power of 100%.

Hypotonic treatment evokes biphasic ATP release across the basolateral membrane of cultured renal epithelia (A6).

In renal A6 epithelia, an acute hypotonic shock evokes a transient increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)) through a mechanism that is sensitive to the P2 receptor antagonist suramin, applied to the basolateral border only. This finding has been further characterized by examining ATP release across the basolateral membrane with luciferin-luciferase (LL) luminescence. Polarized epithelial monolayers, cultured on permeable supports were mounted in an Ussing-type chamber. We developed a LL pulse protocol to determine the rate of ATP release (R(ATP)) in the basolateral compartment. Therefore, the perfusion at the basolateral border was repetitively interrupted during brief periods (90 s) to measure R(ATP) as the slope of the initial rise in ATP content detected by LL luminescence. Under isosmotic conditions, 1 microl of A6 cells released ATP at a rate of 66 +/- 8 fmol min(-1). A sudden reduction of the basolateral osmolality from 260 to 140 mosmol (kg H(2)O)(-1) elevated R(ATP) rapidly to a peak value of 1.89 +/- 0.11 pmol min(-1) (R(ATP)(peak)) followed by a plateau phase reaching 0.51 +/- 0.07 pmol min(-1) (R(ATP)(plat)). Both R(ATP)(peak) and R(ATP)(plat) values increased with the degree of dilution. The magnitude of R(ATP)(plat) remained constant as long as the hyposmolality was maintained. Similarly, a steady ATP release of 0.78 +/- 0.08 pmol min(-1) was recorded after gradual dilution of the basolateral osmolality to 140 mosmol (kg H(2)O)(-1). This R(ATP) value, induced in the absence of cell swelling, is comparable to R(ATP)(plat). Therefore, the steady ATP release is unrelated to membrane stretching, but possibly caused by the reduction of intracellular ionic strength during cell volume regulation. Independent determinations of dose-response curves for peak [Ca(2+)](i) increase in response to exogenous ATP and basolateral hyposmolality demonstrated that the exogenous ATP concentration, required to mimic the osmotic reduction, was linearly correlated with R(ATP)(peak). The link between the ATP release and the fast [Ca(2+)](i) transient was also demonstrated by the depression of both phenomena by Cl(-) removal from the basolateral perfusate. The data are consistent with the notion that during hypotonicity, basolateral ATP release activates purinergic receptors, which underlies the suramin-sensitive rise of [Ca(2+)](i) during the hyposmotic shock.

Temporomandibular joint synovial fluid sampling: estimation of dilution factor using calcium ion concentration

Saline aspirates have been commonly used in the biochemical investigations of temporomandibular joint (TMJ) pathology. However, due to presence of adhesions in the diseased temporomandibular joint, full equilibration between the injected saline and the synovial fluid may not be achieved in all cases. We measured calcium ion concentration in the saline aspirates and the plasma to assess the degree of dilution of the synovial fluid by the injected media. Saline aspirates obtained prior to the arthroscopic examination of 17 patients with painful TMJs not responding to 3 months of conservative treatment were analysed for their calcium content by a highly sensitive spectrophotometric autoanalyser. In 10 patients with unilateral symptoms, the contralateral asymptomatic side was used as a control. Using a concentration volume equation the amount of the synovial fluid in the saline aspirates was calculated. The yield of the saline aspirates was variable ranging from 330 to 1000μl. The mean calcium level was 0.787mg/dl in the symptomatic group (C.I. 95% 0.337–1.237mg/dl) and 0.512mg/dl (C.I. 95% 0.235–0.797) in the asymptomatic group. Using a Student t -test there was no significant difference between the two groups. Furthermore, there was no demonstrable correlation between the volume of the aspirate and its synovial fluid content. This study confirms that the saline aspirate may not be a representative sample of the TMJ synovial fluid, and that expression of the results of the biochemical assays per volume of the aspirate may be misleading.

Multiaxial deformations of end‐linked poly(dimethylsiloxane) networks. III. Effect of entanglement density on strain‐energy density function

AbstractStrain‐energy density functions (W) of end‐linked polydimethylsiloxane (PDMS) networks with different entanglement densities were estimated as a function of the first and second invariants I1 and I2 of Green's deformation tensor on the basis of the quasi‐equilibrium biaxial stress‐strain data. Entanglement densities in the PDMS networks were controlled by varying the precursor PDMS concentration (ϕ0) in end‐linking. The deduced functional form of W [W = C10(I1 − 3) + C01(I2 − 3) + C11(I1 − 3)(I2 − 3) + C20(I1 − 3)2 + C02(I2 − 3)2] is independent of the degree of dilution at network preparation. The contribution of each term in I1 and I2 to total energy depends on whether the precursor PDMS solution before end‐linking belongs to the concentrated regime ϕ0 > ϕc where many entanglement couplings of precursor chains exist or the moderately concentrated regime ϕ0 < ϕc where pronounced entanglement couplings of precursor chains are absent. These results suggest that the rubber elasticity of the end‐linked networks is significantly influenced by the entangled state of precursor chains before end‐linking, and the extra terms in the estimated W that are absent in the prediction of the classical rubber elasticity theories [W = C (I1 − 3)] mainly originate from the effect of trapped entanglements. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2780–2790, 2002

Magnetostructural study of iron–dextran

Dynamic AC magnetic susceptibility, magnetisation and electron microscopy analyses have been performed on several samples derived from a commercial iron–dextran complex. The system contains nanometric spindle shape nanoparticles whose electron diffraction pattern corresponds to that of the iron oxyhydroxide akaganéite (β-FeOOH) and whose magnetic behaviour is superparamagnetic above approximately 100 K. Below such temperature the system exhibits outstanding magnetic relaxation, associated to the blocking of the magnetic moments which result from the incomplete compensation of the intraparticle antiferromagnetic spins. This phenomenon, which is clearly manifested in the temperature dependent out-of-phase susceptibility χ″( T) profile, does not fit the Arrhenius relaxation model and seems not to depend on the type of sample processing, in particular on the degree of particle dilution.

Efficient generation in a chemical oxygen — iodine laser with a low buffer-gas flow rate

The efficient generation in a chemical oxygen — iodine laser (COIL) with a low buffer-gas flow rate for Mach numbers M ≤ 1 is demonstrated. The maximum output power of the COIL was 415 W for a molecular chlorine flow rate of 20 mmol s-1, which corresponds to a chemical efficiency ηch =23%. It is shown that the substitution of the buffer gas CO2 for N2 does not cause any significant variation in the dependence of the output power on the degree of dilution of the active medium.

Catalyst performance testing: the influence of catalyst bed dilution on the conversion observed

A study was performed to investigate the influence of inert dilution on the conversion in a gas–solid laboratory micro-reactor for an irreversible reaction, viz. the catalyzed N 2O decomposition over two different catalysts: FeZSM-5 and Co-La, Al mixed oxide (denoted as Co-La Al-ox). Vertically and horizontally segregated beds, as well as mixed beds with different degrees of dilution were considered. The results showed that catalyst dilution should be applied with caution since it may significantly influence the conversion and lead to an erroneous interpretation of data from catalyst activity measurements and kinetic studies. If the catalyst and the diluting particles are not well-mixed, the conversion reduces significantly due to bypassing and axial dispersion. Also apparent activation energies are reduced. The effects are stronger at high conversion levels (>0.4). Also over beds in which the catalyst and the diluent are perfectly mixed the conversion may be negatively affected by the dilution. It was found that the relative deviation in conversion caused by the dilution can be well estimated from observable parameters, i.e. the observed conversion, the volume fraction of bed dilution, the bed height, and the particle diameter. The relative deviation is approximately proportional to the reaction order. The combination of a high degree of dilution and high conversion should be avoided in catalyst activity measurements.

Changes in estrogenic and androgenic activities at different stages of treatment in wastewater treatment works

Estrogenic and androgenic activities of wastewater were determined during treatment in five wastewater treatment works (WWTWs) in the Untied Kingdom. With one exception, both estrogenic and androgenic activities decreased markedly as wastewater progressed through the plants; removal rates were generally 70% or higher, sometimes reaching 100%. Most of the reduction in activity occurred during secondary (biological) treatment. In both influents and effluents, estrogenic and androgenic activities were appreciably lower in samples collected in August, when the amount of rain had been substantial, compared with samples collected in April and May. Most final effluents contained very low (or nondetectable) estrogenic activity (undetectable to 13 ng/L of estradiol equivalents) and androgenic activity (undetectable to 143 ng/L of dihydrotestosterone [DHT] equivalents), although one (from a WWTW that had only primary treatment) contained relatively high activities (40 ng/L of estradiol equivalents; 4,033 ng/L of DHT equivalents). The type of treatment available at the various WWTWs also affected the activity of the final effluent. The biological significance of these results will depend upon which chemicals contribute to the estrogenic and androgenic activities, because of widely different potencies of different estrogenic chemicals, and on the degree of dilution of the effluents in their receiving waters.

Extinction thickness in the SHS flame propagation in two-layered composite medium

Extinction of the self-propagating high-temperature synthesis (SHS) flame in a condensed composite medium, consisting of adjacent layers of reactants and inert, has been analyzed for the synthesis of functionally graded materials (FGMs), which are anticipated to be useful in future space applications. The essential heterogeneous nature of the SHS flame propagation is appropriately described and the effects of the particle size on the combustion and/or extinction behavior are capture. The analysis, based on the temperature sensitivity of the mass diffusion process in the condensed phase, yields the extinction thickness due to heat transfer to the neighboring inert layer. The study further identifies the extinction thickness as function of the system parameters, which include the mixture ratio, the degree of dilution, the particle size, the representative length of the specimen cross section, and the initial temperature. It is demonstrated that the extinction thickness strongly depends on the particle radius, increasing with increasing particle size, due to the reduced heat generation rate at the particle surfaces. It is also shown that the thickness of the heat of combustion. Furthermore, it is found that preheating can be quite effective in reducing the extinction thickness when there exist restriction in reducing the particle size for the production of composite materials.

Human liver AMP-deaminase--oligomeric forms of the enzyme.

AMP-deaminase (EC 3.5.4.6) is a key enzyme of nucleotide breakdown involved in regulation of adenine nucleotide pool in the liver. Mechanisms regulating activity of the enzyme are not completely elucidated, till now. In this paper experimental data indicating on the potential regulatory significance of changes in oligomeric structure of the enzyme are presented. SDS-PAG electrophoresis of human liver AMP-deaminase revealed the presence of three enzyme fragments. Only largest of them (the protein fragments weighing 68 kDa) reacted immunologically with anti- (human liver) AMP-deaminase antibodies. At physiological pH 7.0, in the absence of regulatory ligands, reaction catalysed by human liver AMP-deaminase was strongly dependent on enzyme concentration used, with half-saturation constant (S0.5) values increasing significantly with the degree of enzyme dilution. Preincubation with activated long-chain fatty acids--substances promoting dissociation of oligomeric enzymes, inhibited the activity of AMP-deaminase studied nearly completely. Gel filtration on Sepharose CL-6B column demonstrated existence of at least three active oligomeric forms of human liver AMP-deaminase. We postulate that oligomeric structure of the enzyme is a factor determining regulatory profile of AMP-deaminase studied.

CHANGES IN ESTROGENIC AND ANDROGENIC ACTIVITIES AT DIFFERENT STAGES OF TREATMENT IN WASTEWATER TREATMENT WORKS

Estrogenic and androgenic activities of wastewater were determined during treatment in five wastewater treatment works (WWTWs) in the Untied Kingdom. With one exception, both estrogenic and androgenic activities decreased markedly as wastewater progressed through the plants; removal rates were generally 70% or higher, sometimes reaching 100%. Most of the reduction in activity occurred during secondary (biological) treatment. In both influents and effluents, estrogenic and androgenic activities were appreciably lower in samples collected in August, when the amount of rain had been substantial, compared with samples collected in April and May. Most final effluents contained very low (or nondetectable) estrogenic activity (undetectable to 13 ng/L of estradiol equivalents) and androgenic activity (undetectable to 143 ng/L of dihydrotestosterone [DHT] equivalents), although one (from a WWTW that had only primary treatment) contained relatively high activities (40 ng/L of estradiol equivalents; 4,033 ng/L of DHT equivalents). The type of treatment available at the various WWTWs also affected the activity of the final effluent. The biological significance of these results will depend upon which chemicals contribute to the estrogenic and androgenic activities, because of widely different potencies of different estrogenic chemicals, and on the degree of dilution of the effluents in their receiving waters.

The gas‐phase oxidation ofn‐hexadecane

AbstractSincen‐hexadecane or cetane is a reference fuel for the estimation of cetane numbers in diesel engines, a detailed chemical model of its gas‐phase oxidation and combustion will help to enhance diesel performance and reduce the emission of pollutants at their outlet. However, until recently the gas‐phase reactions ofn‐hexadecane had not been experimentally studied, prohibiting a validation of oxidation models which could be written.This paper presents a modeling study of the oxidation ofn‐hexadecane based on experiments performed in a jet‐stirred reactor, at temperatures ranging from 1000 to 1250 K, 1‐atm pressure, a constant mean residence time of 0.07 s, and high degree of nitrogen dilution (0.03 mol% of fuel) for equivalence ratios equal to 0.5, 1, and 1.5. A detailed kinetic mechanism was automatically generated by using the computer package (EXGAS) developed in Nancy. The long linear chain of this alkane necessitates the use of a detailed secondary mechanism for the consumption of the alkenes formed as a result of primary parent fuel decomposition. This high‐temperature mechanism includes 1787 reactions and 265 species, featuring satisfactory agreement for both the consumption of reactants and the formation of products. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 574–586, 2001

Influence of mixing and extraction parameters on virgin olive oil quality

The mixing time, the temperature and the degree of dilution of olive paste are the main parameters liable to change during mixing and oil ext raction. They can greatly differ from a processing run to another, with variations being observed in Tuscan oil mills, between 26oC and 36oC, 40’ and 90’, and 10% and 50% respectively, for the temperature, the mixing time and the water added during the centrifugal extraction. This note reports on the results of some experimental trials run during the 1998 olive oil year in Tuscany. The mixing time and temperature as well as the olive paste dilution were changed one at a time and were assessed for their influence on extraction yield and oil quality. The best conditions to optimise the product yield and quality were identified.

Membrane crumpling and restricted swelling in onion phases

We have observed a deviation from one-dimensional swelling behaviour in onion phases. This is explained in terms of crumpling of each membrane due to its flexibility together with a lateral membrane tension which depends on the degree of dilution.

Multiple Light Scattering by Spherical Particle Systems and Its Dependence on Concentration: A T-Matrix Study

The T-matrix method has been used to calculate scattering cross-sections of two spherical particles close to each other. By comparing our results with those expected for infinite distance, we can determine the maximum distance required to produce interparticle light-scattering interactions. As a result, we can determine the degree of dilution needed in a particle suspension to remain within the single-scattering approximation. Cross sections have been calculated for a relative refractive index m=1.2 and a range of particle sizes and separations. Since the approach in this paper assumes double scattering as the first mechanism for beginning multiple scattering, our results will be compared with those arising from the condition that the optical depth is less than unity, τ<1. It is shown that this condition, widely used in transfer theory, is more restrictive than ours except for the smallest particles, where double scattering becomes the main agent for multiple scattering.