Principle Of Dilution Research Articles

An Enigma Called Homeopathy

When I speak of an enigma, I adhere to its definition; the one given by the RAE (Royal Spanish Academy), which means: a statement whose meaning is artificially concealed to make it difficult to understand or interpret. Homeopathy (pathos=disease, homoios=similar); was created by the German Doctor Samuel Hahnemann in 1796. He was a man with a restless spirit and deeply dissatisfied with late 18th century medicine. After multiple verifications, Hahnemann creates the law that supports the homeopathic doctrine, the Law of Similars. It states that: ‘‘in order to cure a given illness, a remedy must be taken which, when administered to a healthy subject, will cause illnesses ‘and if it is capable of making one sick, it is also capable of curing. This principle of dilution accompanies the Law of Similars [1].

Discharges of Nuclear Medicine Radioisotopes: The Impact of an Abatement System.

Clinical uses of radiopharmaceuticals imply the administration of radioactive substances that are mainly excreted through urine. The Nuclear Medicine Department at the Instituto Nacional de Cancerología (INC-COL) in Bogota, Colombia, administers radiopharmaceuticals for diagnostics and treatment to many patients, resulting in tens of cubic meters of radioactive waste water (WW) every day. As Colombian regulatory limits for liquid radioactive discharges to the sewer system are lower than in other countries, longer WW decay times are required, even when an in-house waste water treatment plant (WWTP) is used. To fulfill the requirements for controlled disposal of radioactive discharges, a complementary abatement system was implemented to retain WW for periods as long as 360 d, and was connected to the hospital´s WWTP. These holding times can cause major changes in the WW physicochemical parameters, reaching levels higher than acceptable. In this study, we evaluate the decontamination and decay efficiency of the retention system using water quality parameters and the amount of radioactivity in the effluents stored in the tanks and the WWTP. According to the results, to maintain the physicochemical parameters below acceptable levels, biological and chemical treatment of decayed WW is necessary before discharging it into urban waste water. Using the principles of dilution, retention, and decay, an integral radioactive WW management system was implemented favoring the quality of discharges and activity levels to the sewer system, with efficiencies close to 100% for WW from discharges in diagnostic procedures ranging from 98% (131I) to 100% (177Lu) for WW from discharges in therapeutic procedures. Activity concentration assessment in medically-derived radionuclides using an in-house waste water treatment plant (WWTP) and a complementary abatement system; an in-house WWTP could be used as an abatement system for short-lived radionuclides; and a tank-based abatement system attached to the in-house WWTP showed higher efficiencies for long-lived radionuclides and adequate physicochemical parameters for the discharge to the city sewage system.

Kinetics of Iron Absorption From Ferrous Fumarate With Galacto-oligosaccharides Measured by Stable-isotope Appearance Curves in Iron Depleted Women in Switzerland

ObjectivesPrebiotic galacto-oligosaccharides (GOS) have shown promising results in enhancing the absorption of oral supplemental iron in form of ferrous fumarate (FeFum) in iron depleted adults. The mechanism behind this effect is unknown. We aimed to assess the absorption profile of FeFum given with and without GOS using stable isotope appearance curves (SIACs). MethodsWe conducted a controlled, single-center, prospective cross-over trial in iron depleted women between Sept and Nov 2019 at the Laboratory of Human Nutrition, ETH Zurich, Switzerland. All women (n = 11; median SF = 15.2 μg/L) received two supplemental iron doses of 14 mg in form of FeFum containing 6 mg of isotopic tracers (57Fe or 58Fe). The supplemental iron doses were administered in random order on d 1 and 15 after an overnight fast. The supplement combinations were: 1) 57FeFum + 300 ml water; and 2) 58FeFum + 15 g GOS + 300 ml water. Eleven blood samples were collected up to 24 h after administration of the iron supplements to determine serum iron appearance. Fractional iron absorption (FIA) of the isotopic tracers was calculated in whole blood collected 14 days after administration of each of the supplemental iron doses on the basis of the shift in iron isotope ratios according to the principle of isotope dilution. ResultsThere was a trend towards increased FIA and total absolute AUC of the SIAC from FeFum given with 15 g GOS compared to without (P = 0.064; P = 0.080 respectively). Estimated timepoints of the peak serum isotope concentration were not different (P = 0.096). Relative SF and relative bioavailability correlated significantly (P = 0.037). In subjects with a lower SF the increase in bioavailability of iron when given with GOS was more pronounced compared to participants with higher SF. ConclusionsAdding 15 g GOS to FeFum did not result in a different absorption profile compared to without GOS. The enhancing effect of GOS seems to depend on iron status, even though overall the improvement of iron absorption when given with 15 g GOS did not reach significance, probably due to the small sample size. Since women with a low iron status can benefit the most from an increase in iron bioavailability, the use of GOS for the improvement of iron bioavailability from FeFum in women with very low iron stores is promising. Funding SourcesInnosuisse, Swiss Innovation Agency, in collaboration with Antistress AG - Burgerstein Vitamine.

Simultaneously Enhancing Photoluminescence Quantum Efficiency and Optical Gain of Polyfluorene via Backbone Intercalation of 2,5‐Dimethyl‐1,4‐Phenylene

AbstractSimultaneous enhancement of photoluminescence quantum efficiency (PLQE) and optical gain in semiconducting polymer films is desirable for optically‐ or electrically‐pumped organic solid‐state lasers. In this work, a simple self‐dilution effect is achieved by introducing a small amount (≈10% by weight) of 2,5‐dimethyl‐1,4‐phenylene (DP) units in the backbone of poly(9,9‐dioctylfluorene) (PFO). The resulting copolymers, compared with PFO (PLQE 39%), exhibit a significantly increased PLQE (66%) while keeping similar absorption and photoluminescence profile, concomitant with an enhancement in optical gain properties. The radiative decay rate increases sharply along with a sustaining reduction in the non‐radiative decay rate in these copolymers, following similar principle of physical dilution of a luminescent compound in solution or in a polymer matrix. Among all the copolymers, the one containing 10% DP units exhibits the lowest amplified spontaneous emission/distributed feedback laser threshold (10.9 nJ/1.4 nJ, eightfold reduction), and the highest gain coefficient (54.4 cm−1). The results demonstrate that a moderate DP/fluorene ratio can maximize the beneficial self‐dilution effects. These investigations shed light on new design strategies to achieve conjugated polymers with concurrent high PLQE and large optical gain properties.

Laminar burning characteristics of premixed methane-dissociated methanol-diluent mixtures

The influence of dissociated methanol (DM) and diluent (CO2 and N2) addition on methane was investigated in a constant volume chamber under initial conditions of 3 bar and 343 K. CO was also added in separate proportions instead of DM under the same conditions to assess its effect. The laminar burning velocity, Markstein length and flame instability were analyzed systematically under various equivalence ratios (0.8–1.4), dissociated methanol gas ratios (40 and 80%), CO ratios (40 and 80%) and dilution ratios (0–15%). Furthermore, the flame speed of the fuel mixture and the production rate of key reactants were analyzed based on the calculation results of the Aramco Mech 2.0 mechanism to determine the influence principles of dilution. The results show that dissociated methanol gas increases the flame speed of the mixtures and promotes instability of the flame, and H2 is the dominant component in enhancing the combustion process. Within the dilution ratio range of this study, the diluents decrease the laminar burning velocity of the mixtures since the addition of diluent gas decreases the concentration of key reactants, such as H and OH. The addition of diluent gas can inhibit the flame instability, but the effect is not clear. Compared with N2, the effect of CO2 is more significant.

Experimental Study of a Downward Directed Water Mist suppressing a Diffusion Flame

Interaction of fires with water have been a focus of study for human kind from the times immemorial. With the recent advances in water-based suppression, and restrictions put on halon usage, sprinklers and water-mist based fire suppression systems have become popular for industrial usage. Of this water mist is an interesting candidate, for it has advantages and to name a few would be less water requirement, non-wetting nature, gas phase action on fire. Water mist, as an effective fire suppressant, works on the principle of oxygen dilution and flame cooling.In this work, we are studying the action of water mist on a diffusion flame. The water mist was generated from a Delavan nozzle, fed with high pressure water, which is then directed downward into the raising flame. A circular burner fed with Methane in a controlled manner generated the diffusion flame. The reason to prefer a gas burner is to have a control over heat release rate which will help in simulating various fuel sources of different burning rate. A glass cubicle was used to isolate the experiments from ambient disturbances. A Digital SLR camera was used to record the flame and subsequently the images were processed to obtain flame height. Particle Image Velocimetry was used to study the effect of the flame on the water mist., by imaging the Mie scattered laser light from the droplets. Parameters that were varied were the injection pressure and flow rate of the Methane into the burner.Visual imaging from the camera indicated that there were occasional flame tip flattening during the suppression mechanism. The flame luminosity is diminished and the diffusion flame height is reduced due to the action of the water mist. Moreover, this effect is more pronounced for smaller flame than larger flame, indicating the role of the buoyancy in fire suppression effectiveness. The PIV results show that the droplets are slowed down very close to the nozzle due to the flame. Also, a recirculation zone is observed at the periphery of the spray cone, very close to the nozzle. It is a toroidal vortex that is generated due to the interaction, and the droplets thrown away from the spray cone gets trapped into this flow. The flow structure is present in a highly turbulent region and is identified in the mean field. Another finding is that close to the burner, fine droplets that could make it to the base, gets entrained into the flame. It is expected that the droplets tend to be entrained into the larger flame, as the entrainment is stronger for large flame, compared to the smaller flame. But the PIV results indicate otherwise, which is attributed to the larger size of droplets making its way close to the burner.We believe that these results will enlarge our understanding of the suppression mechanism of water mist and could form a basis for validating various simulation models.

Quantifying atmospheric N deposition in dryland ecosystems: A test of the Integrated Total Nitrogen Input (ITNI) method

Estimating nitrogen (N) deposition to terrestrial ecosystems is complicated by the multiple forms and routes of N loading from the atmosphere. We used the integrated total nitrogen input (ITNI) method, which is based on the principle of isotope dilution within a plant-liquid-sand system, to quantify N inputs to coastal sage scrub ecosystems in Riverside, California. Using the ITNI method, we measured atmospheric N deposition of 29.3 kg N ha−1 yr−1 over a range of aboveground plant biomass of 228 to 424 g m−2. From 85 to 96% of the atmospheric N inputs were taken up by plants in the ITNI modules with most of the assimilation mediated by, and stored in, aboveground biomass. Parallel measurements using conventional approaches yielded deposition rates of 25.2 kg N ha−1 yr−1 when using the inferential method and 4.8 kg N ha−1 yr−1 using throughfall collectors. The relatively low throughfall estimates were attributed to canopy retention of inorganic N, low rainfall, and to the fact that the throughfall flux data did not include organic N and stomatal uptake of N gases. Also, during dry periods, frequent watering of ITNI modules may have increased stomatal conductance and led to overestimates of N deposition. Across published studies that used the ITNI method, areal N deposition rates varied by ~40-fold, were positively correlated with plant biomass and 90% of the variability in measured deposition rates can be explained by plant biomass production. The ITNI method offers a holistic approach to measuring atmospheric N deposition in arid ecosystems, although more study is needed to understand how watering rates effect N deposition measurements.

An overview of the role and significance of 15N methodologies in quantifying biological N2 fixation (BNF) and BNF dynamics in agro-ecosystems

Quantitative estimates of BNF are needed to improve our understanding of the ecology of N in the environment and aid efforts to improve agricultural N management. Static models based on the principle of 15N isotope dilution have been proposed to estimate the proportion of N in a N2-fixing species that is derived from the atmosphere via biological N2 fixation. Furthermore, equations have been developed to quantify the movement of biologically fixed N between neighboring species or from legumes to cereals in crop rotations. The present paper is structured to provide a comprehensive overview of these methods in a logical and systematic manner. While the relevant literature is vast, some aspects have fortunately been covered by recent in-depth reviews which will be identified and briefly summarized. The overview will emphasize the more practical indirect methodologies based either on artificial 15N enrichment or 15N depletion, or alternatively on 15N natural abundance. In considering methods used to estimate symbiotic dependence, the major structural division is whether or not a non-N2-fixing reference plant is employed, and approaches taken to remove this source of error are described. Four examples are provided to illustrate the contemporary success of 15N-based methods, one in basic research involving endophytic BNF, and three in applied research involving legume breeding for enhanced BNF, the response of legumes to climate change and biotic and abiotic factors affecting legume symbiotic performance.

Metal nanoparticle induced hormetic activation: a novel mechanism of homeopathic medicines

High-potency homeopathic remedies, 30c and 200c have enormous dilution factors of 1060 and 10400 respectively. Therefore, the presence of physical entities in them is inconceivable. As a result, their efficacy is highly debated and often dismissed as a placebo. Despite several hypotheses postulated to explain the claimed homeopathic efficacy, none have satisfactorily answered the qualms of the sceptics. Against all beliefs and principles of conventional dilution, we have shown that nanoparticles (NPs) of the starting metals are unequivocally found in the 30c and 200c remedies at concentrations of a few pg/ml. In this paper, our aim was to answer the important question of whether such negligible metal concentrations elicit a biological response. Metal-based homeopathic medicines (30c and 200c) were analysed at doses between 0.003%v/v and 10%v/v in in-vitro HepG2 cell-line. Upon treatment, cell response was estimated by MTT assay, FACS and total intracellular protein. Experiments were performed to discern whether the hormesis was a cell-activation or a proliferation effect. Remedies at doses containing a few femtograms/ml levels of the starting metals induced a proliferation-independent hormetic activation by increasing the intracellular protein synthesis. The metal concentrations (at fg/ml) were a billion-fold lower than the studies with synthetic NPs (at μg/ml). Further, we also highlight a few plausible mechanisms initiating a hormetic response at a billion-fold lower dose. Hormetic activation has been shown for the first time with standard homeopathic high-potency remedies. These findings should have a profound effect in understanding these extreme dilutions from a biological perspective.

Influenza Vaccination of Healthcare Workers: Critical Analysis of the Evidence for Patient Benefit Underpinning Policies of Enforcement.

BackgroundFour cluster randomized controlled trials (cRCTs) conducted in long-term care facilities (LTCFs) have reported reductions in patient risk through increased healthcare worker (HCW) influenza vaccination. This evidence has led to expansive policies of enforcement that include all staff of acute care hospitals and other healthcare settings beyond LTCFs. We critique and quantify the cRCT evidence for indirect patient benefit underpinning policies of mandatory HCW influenza vaccination.MethodsPlausibility of the four cRCT findings attributing indirect patient benefits to HCW influenza vaccination was assessed by comparing percentage reductions in patient risk reported by the cRCTs to predicted values. Plausibly predicted values were derived according to the basic mathematical principle of dilution, taking into account HCW influenza vaccine coverage and the specificity of patient outcomes for influenza. Accordingly, predicted values were calculated as a function of relevant compound probabilities including vaccine efficacy (ranging 40–60% in HCWs and favourably assuming the same indirect protection conferred through them to patients) × change in proportionate HCW influenza vaccine coverage (as reported by each cRCT) × percentage of a given patient outcome (e.g. influenza-like illness (ILI) or all-cause mortality) plausibly due to influenza virus. The number needed to vaccinate (NNV) for HCWs to indirectly prevent patient death was recalibrated based on real patient data of hospital-acquired influenza, with adjustment for potential under-detection (5.2-fold), and using favourable assumptions of HCW-attributable risk (ranging 60–80%).ResultsIn attributing patient benefit to increased HCW influenza vaccine coverage, each cRCT was found to violate the basic mathematical principle of dilution by reporting greater percentage reductions with less influenza-specific patient outcomes (i.e., all-cause mortality > ILI > laboratory-confirmed influenza) and/or patient mortality reductions exceeding even favourably-derived predicted values by at least 6- to 15-fold. If extrapolated to all LTCF and hospital staff in the United States, the prior cRCT-claimed NNV of 8 would implausibly mean >200,000 and >675,000 patient deaths, respectively, could be prevented annually by HCW influenza vaccination, inconceivably exceeding total US population mortality estimates due to seasonal influenza each year, or during the 1918 pandemic, respectively. More realistic recalibration based on actual patient data instead shows that at least 6000 to 32,000 hospital workers would need to be vaccinated before a single patient death could potentially be averted.ConclusionsThe four cRCTs underpinning policies of enforced HCW influenza vaccination attribute implausibly large reductions in patient risk to HCW vaccination, casting serious doubts on their validity. The impression that unvaccinated HCWs place their patients at great influenza peril is exaggerated. Instead, the HCW-attributable risk and vaccine-preventable fraction both remain unknown and the NNV to achieve patient benefit still requires better understanding. Although current scientific data are inadequate to support the ethical implementation of enforced HCW influenza vaccination, they do not refute approaches to support voluntary vaccination or other more broadly protective practices, such as staying home or masking when acutely ill.

The Influence of Scleral Flap Thickness, Shape, and Sutures on Intraocular Pressure (IOP) and Aqueous Humor Flow Direction in a Trabeculectomy Model

Intraocular pressure and aqueous humor flow direction determined by the scleral flap immediately after trabeculectomy are critical determinants of the surgical outcome. We used a large-scale model to objectively measure the influence of flap thickness and shape, and suture number and position on pressure difference across the flap and flow of fluid underneath it. The model exploits the principle of dynamic and geometric similarity, so while dimensions were up to 30× greater than actual, the flow had similar properties. Scleral flaps were represented by transparent 0.8- and 1.6-mm-thick silicone sheets on an acrylic plate. Dyed 98% glycerin, representing the aqueous humor was pumped between the sheet and plate, and the equilibrium pressure measured with a pressure transducer. Image analysis based on the principle of dye dilution was performed using MATLAB software. The pressure drop across the flap was larger with thinner flaps, due to reduced rigidity and resistance. Doubling the surface area of flaps and reducing the number of sutures from 5 to 3 or 2 also resulted in larger pressure drops. Flow direction was affected mainly by suture number and position, it was less toward the sutures and more toward the nearest free edge of the flap. Posterior flow of aqueous humor was promoted by placing sutures along the sides while leaving the posterior edge free. We demonstrate a new physical model which shows how changes in scleral flap thickness and shape, and suture number and position affect pressure and flow in a trabeculectomy.

A Study of Water Crystal Growing Based on Dilution and Succussion Theory of Homeopathy

By studying the formation of snowflakes, scientists have found that frequency data can be stored in water. Using the homeopathic principles of dilution and succussion, this study explored the relationship between aqueous information transmission and differences in the formation of water crystals. We utilized three different types of experimental solution: bali water, distilled water, and ionized water, and studied the water crystals sprouting from the resulting ice crystals. From the four significant phases of morphological change (mother tincture, 1X, 4c, and 30c), it was determined that at higher dilution ratios, crystals grown in either distilled or ionized water developed from crystallites into a single-body structure, approaching the higher energy form of straight edge hexagonals. This phenomenon demonstrates the features of coherent domains and water clusters, both of which match the homeopathic principles of energy waves and information transmission.

Use of isotope dilution method to predict bioavailability of organic pollutants in historically contaminated sediments.

Many cases of severe environmental contamination arise from historical episodes, where recalcitrant contaminants have resided in the environment for a prolonged time, leading to potentially decreased bioavailability. Use of bioavailable concentrations over bulk chemical levels improves risk assessment and may play a critical role in determining the need for remediation or assessing the effectiveness of risk mitigation operations. In this study, we applied the principle of isotope dilution to quantify bioaccessibility of legacy contaminants DDT and PCBs in marine sediments from a Superfund site. After addition of 13C or deuterated analogues to a sediment sample, the isotope dilution reached a steady state within 24 h of mixing. At the steady state, the accessible fraction (E) derived by the isotope dilution method (IDM) ranged from 0.28 to 0.89 and was substantially smaller than 1 for most compounds, indicating reduced availability of the extensively aged residues. A strong linear relationship (R2 = 0.86) was found between E and the sum of rapid (Fr) and slow (Fs) desorption fractions determined by sequential Tenax desorption. The IDM-derived accessible concentration (Ce) was further shown to correlate closely with tissue residue in the marine benthic polychaete Neanthes arenaceodentata exposed in the same sediments. As shown in this study, the IDM approach involves only a few simple steps and may be readily adopted in laboratories equipped with mass spectrometers. This novel method is expected to be especially useful for historically contaminated sediments or soils, for which contaminant bioavailability may have changed significantly due to aging and other sequestration processes.

Ambient Volatile Organic Compounds (VOCs) pollution in Isolo Industrial Area of Lagos State, Southwestern – Nigeria

Air pollution by volatile organic compounds is based on the principles of dilution, diffusion and dispersion. The air samples were collected by passive sampler (ORSA 5). The air samplers were exposed to a height of 1.5 - 2.0 m and sampling was carried out four times a month for a period of 12 months. The adsorbed VOCs were desorbed with carbondisulphide (CS2) and the solution analysed using Gas Chromatography (GC) fitted with Flame Ionization Detector (FID). The results from analysis of the air samples collected showed that twenty-six (26) VOCs were captured in Isolo Industrial area. The VOCs were classified thus: aromatics 41%, halogenated 42%, esters 3%, ketones 8%, alcohols 4%, and ethers 2%. There is a significant difference (P < 0.05) between the levels of VOCs in Isolo Industrial area. The meteorological parameters showed significant correlations with the ambient concentrations of VOCs. The principal component analysis revealed that the major sources of VOCs in the industrial area are mainly anthropogenic. Evaporative, vehicular/petroleum product, solvent and Industrial emission were identified as sources of VOCs in the studied industrial area with industrial emissions dominating.Keywords: Pollution, Ambient, Gas Chromatography, Industrial, Anthropogenic.

Effect of sample dilution on estimated values of antioxidant capacity by photochemiluminiscence method

This paper describes principles of a proper dilution of samples used for the determination of antioxidant capacity by means of a photochemiluminiscence method using the instrument Photochem (Analytik Jena AG). The authors used the method ACL (Lipid-soluble Antioxidant Capacity), which is one of two methods enabling to measure in this instrument. It was demonstrated that values measured by the photochemiluminiscence method ACL were influenced by the degree of sample dilution. When studying effects of dilution of samples of wine and rutin, it was demonstrated that there is a non-linear correlation between the degree of dilution and measured values of antioxidant capacity. At low molar amount of substance (i.e. at 0.5 and 1.0 nmol), the measured value of rutin inhibition was higher than the same that molar amount of trolox. At higher molar amounts (i.e. 3; 4 and 5 nmol), the inhibition value of trolox was higher. This dependent change can be explained by means of a different effectiveness of antioxidants and a different stability of their products with radicals.

Measurement of Isotope Abundance Variations in Nature by Gravimetric Spiking Isotope Dilution Analysis (GS-IDA)

Subtle variations in the isotopic composition of elements carry unique information about physical and chemical processes in nature and are now exploited widely in diverse areas of research. Reliable measurement of natural isotope abundance variations is among the biggest challenges in inorganic mass spectrometry as they are highly sensitive to methodological bias. For decades, double spiking of the sample with a mix of two stable isotopes has been considered the reference technique for measuring such variations both by multicollector-inductively coupled plasma mass spectrometry (MC-ICPMS) and multicollector-thermal ionization mass spectrometry (MC-TIMS). However, this technique can only be applied to elements having at least four stable isotopes. Here we present a novel approach that requires measurement of three isotope signals only and which is more robust than the conventional double spiking technique. This became possible by gravimetric mixing of the sample with an isotopic spike in different proportions and by applying principles of isotope dilution for data analysis (GS-IDA). The potential and principle use of the technique is demonstrated for Mg in human urine using MC-TIMS for isotopic analysis. Mg is an element inaccessible to double spiking methods as it consists of three stable isotopes only and shows great potential for metabolically induced isotope effects waiting to be explored.

Investigation into the use of rapid (alternative) microbial detection methods to determine bioburden of NHS pharmacy-manufactured non-sterile medicines†

BackgroundRapid microbiological methods (RMMs) have been shown to improve aseptic NHS QA activities. This study investigates the potential to use these new rapid qualitative technologies for quantitative bioburden testing. The...

Advances in 15N-tracing experiments: new labelling and data analysis approaches

To obtain an in-depth understanding of soil nitrogen dynamics, it is necessary to quantify a variety of simultaneously occurring gross nitrogen transformation processes. In order to do so, most studies apply 15N in a disturbed soil-microbial-root system and quantify gross rates based on the principles of 15N isotope dilution. However, this approach has several shortcomings. First, studying disturbed soil provides only limited information on in situ soil nitrogen dynamics. Secondly, the analytical data analysis allows the quantification of total production and consumption rates of the labelled pool, but does not provide information on process-specific transformation rates. Combining in situ 15N isotope labelling over 1-2weeks with numerical data analysis allows determining process-specific gross nitrogen transformations in undisturbed soils under field conditions in the presence of live roots and their associated microbial communities. This has the potential to increase our understanding of nitrogen dynamics in the soil environment.

Effects of concentration of dispersions on particle sizing during production of fine particles in wet grinding process

Stirred media milling is a prospective technology for producing colloidal dispersions by means of wet grinding process. In the past, many researchers have studied the effects of different operating parameters such as size, shape, nature and quantity of grinding medium, the speed of agitator in grinding chamber, the feed rate of dispersions, etc. in stirred media mills. However, it is still less known how particle sizing which generates valuable information of particle size of the product to interpret, control and optimize the grinding process, is influenced by the concentration of the dispersion during stirred media milling where particles change their size from micron to colloidal range rapidly. One of the reasons of this lack had been our incapability in the past to study the particle size distribution of dispersions without dilution. The recent advent of acoustic attenuation spectroscopy is known to be capable of studying dispersions without dilution, under real process conditions and on line. The study employs acoustic attenuation spectroscopy to investigate the effects of concentration of dispersions of CaCO 3 on its particle sizing during size reduction process in a stirred media mill (LabStar manufactured by NETZSCH). The dispersions of CaCO 3 at 5%, 10%, 20% and 30% (m/m) were studied about six hours under a selected set of operating conditions. Contrary to the existing knowledge obtained through other techniques of particle sizing that are based on the principle of dilution, acoustic attenuation spectroscopy shows that, under certain grinding time at given operating conditions, increase in concentration of dispersion results in better grinding results yielding smaller particles. The causes behind the differences in results of acoustic attenuation spectroscopy and dynamic light scattering have been thoroughly investigated. We find certain limitations of acoustic attenuation spectroscopy in particle sizing. A typical phenomenon which causes misleading trends in particle sizing is multiple scattering in acoustic measurements. Multiple scattering, particularly, influences acoustic results when particles approach to fine size range during size reduction process.

Hydrophobic hydration processes: General thermodynamic model by thermal equivalent dilution determinations

The “hydrophobic hydration processes” can be satisfactorily interpreted on the basis of a common molecular model for water, consisting of two types of clusters, namely WI and WII accompanied by free molecules WIII. The principle of thermal equivalent dilution (TED) is the potent tool (Ergodic Hypothesis) employed to monitor the water equilibrium and to determine the number ξw of water molecules WIII involved in each process. The hydrophobic hydration processes can be subdivided into two Classes: Class A includes those processes for which the transformation A(−ξwWI→ξwWII+ξwWIII+cavity) takes place with the formation of a cavity, by expulsion of ξw water molecules WIII whereas Class B includes those processes for which the opposite transformation B(−ξwWII−ξwWIII→ξwWI−cavity) takes place with reduction of the cavity, by condensation of ξw water molecules WIII. The number ξw depends on the size of the reactants and measures the extent of the change in volume of the cavity. Disaggregating the thermodynamic functions ΔHapp and ΔSapp as the functions of T (or lnT) and ξw has enabled the separation of the thermodynamic functions into work and thermal components. The work functions ΔGWork, ΔHWork and ΔSWork only refer specifically to the hydrophobic effects of cavity formation or cavity reduction, respectively. The constant self-consistent unitary (ξw=1) work functions obtained from both large and small molecules indicate that the same unitary reaction is taking place, independent from the reactant size. The thermal functions ΔHTh and ΔSTh refer exclusively to the passage of state of water WIII.Essential mathematical algorithms are presented in the appendices.