Freezing Point Method Research Articles

Method verification of serum and urine osmolality by Osmo pro micro-osmometer analyzer using freezing point method

Method verification of serum and urine osmolality by Osmo pro micro-osmometer analyzer using freezing point method

Acute and Chronic Posterior Pituitary Insufficiency Among Traumatic Brain Injury Patients at a Tertiary Care Center

Abstract Background: Traumatic brain injury (TBI) is the leading cause of death and disability in young adults. Disorders of salt and water balance are the most commonly recognized medical complications in the immediate post-TBI period and contribute to early morbidity and mortality. Objective: We aimed to evaluate the prevalence of acute (during hospital stay) and chronic posterior pituitary dysfunction in patients of head injury admitted at our tertiary care hospital. Study Design: Prospective, Observational study. Participants: 136 patients, attending tertiary care in North India with TBI with radiological evidence of head injury. Methodology: The severity of brain injury was assessed by the Glasgow Coma Scale (GCS), and Modified Rankin Scale (MRS) score at the time of admission. Lab measurements, apart from routine CBC and biochemical tests, included tests of serum and urinary osmolality, serum sodium, cortisol, and thyroid function test during the hospital stay. All patients were monitored closely during the hospital stay. Surviving patients were evaluated at 3, 6, and 12 months of follow-up. Urinary output and water deprivation tests were done to determine chronic posterior pituitary dysfunction. The results were compared against normative data obtained from 25 matched, healthy controls. Serum & urinary osmolality was measure by the freezing point method. Diabetes insipidus (DI) and Syndrome of inappropriate ADH secretion (SIADH) were diagnosed according to standard criteria. Results: Of 136 patients admitted, 61 (44.85%) had a mild head injury (GCS, ≤8), 47 (35.55%) had a moderate injury (GCS, 9-12), and 27 (19.85%) had a severe injury (GCS, 13-15). DI occurred in 10 patients (7.4%), while SIADH was observed in 4 patients in the immediate TBI period. Risk factors for diabetes insipidus were GCS of ≤ 8 at admission, midline shift, and surgical intervention. DI was an independent risk factor for death. There was a negative correlation between the presence of DI and GCS score (r, -0.367). Most of the patients with DI (8 out of 10) died during the hospital stay. One patient persisted to have partial diabetes insipidus and another one SIADH at three months post-TBI; both patients had recovered at six months of follow-up. No new case of DI or SIADH occurred on the follow up to 12 months. Conclusion: The incidence of acute DI in severe head injury (GCS ≤ 8) could be an indicator of the severity of TBI, and associated with increased mortality as most of our patients died during the hospital stay.

Oligosaccharides composition of Descurainiae sophia exerts anti-heart failure by improving heart function and water-liquid metabolism in rats with heart failure

PurposeTo investigate the protective effect of Oligosaccharides composition of Descurainiae sophia on doxorubicin-induced heart failure in rats, and to study its mechanism. MethodA rat model of heart failure was established in 180−220 g male Sprague-Dawley rats by low-dose intraperitoneal injection of doxorubicin for 6 weeks. Four weeks after continuous administration, echocardiography was used to detect left ventricular end diastolic diameter (LVEDD) and end systolic diameter (LVESD) in each group, and left ventricular short axis shortening rate (LVFS) and ejection fraction (LVEF) were calculated. ELISA method was used to detecte the levels of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), troponin I (cTnI), creatine kinase (CK), angiotensin II (Ang II), aldosterone (ALD), arginine pressurization AVP, Renin, Endothelin (ET-1), Nitric Oxide (NO), AQP2 in urine. 6 h cumulative urine output was measured by metabolic cage method after administration for 3 weeks. The urine osmotic pressure was measured by freezing point method. The expression of AQP2 protein in kidney was detected by Western blot method. The changes of myocardial morphology were observed. ResultsCompared with the normal control group, the heart rate of the model group was significantly increased (P < 0.01). LVESD and LVEDD were significantly increased (P < 0.01), LVEF and LVFS were significantly decreased (P < 0.01). The levels of CK, cTnI, NO, ET-1, BNP, ANP, ALD, AngII, Renin, AQP2, AVP and osmotic pressure were significantly increased (P < 0.01). Urine output was significantly decreased (P < 0.01). The heart HE showed obvious lesions. Compared with the model group, the Oligosaccharides composition of Descurainiae sophia significantly reduced the heart rate (P < 0.05), decreased LVESD and LVEDD (P < 0.01 or P < 0.05), and increased LVFS and LVEF values (P < 0.01). Oligosaccharides composition of Descurainiae sophia could significantly improve pathological damage of the heart, decrease the levels of cTnI, BNP, AngII, ALD, Renin, AVP in the serum, osmotic pressure and AQP2in the urine (P < 0.01 or P < 0.05), down-regulate the expression of AQP2 protein in the renal(P < 0.01), increase urine volume (P < 0.05). ConclusionOligosaccharides composition of Descurainiae sophia can significantly improve cardiac function and the disorder of water metabolism in rats with heart failure. Oligosaccharides composition of Descurainiae sophia exerts anti- heart failure through the RAAS system and the arginine vasopressin system.

Optimization of Anhydrous Coolant’s Base Fluid and the Evaluation of Low Temperature Performance

The low-temperature viscosity of anhydrous coolant is reduced by adding ethylene glycol to the propylene glycol base fluid, and the evaluation method of low-temperature fluidity is also studied. The experimental results show that the low-temperature fluidity of anhydrous coolant can be greatly improved by the participating of ethylene glycol. Freezing point method is usually used for measuring the low temperature performance of coolant, but for “long icing process” anhydrous coolant, beginning-crystal point shows more practical reference value. Therefore, freezing point, beginning-crystal point and low-temperature fluidity should be considered at the same time when evaluation the low temperature performance of anhydrous coolant.

Change of aquaporin-1 in rat models of kidney-yang-deficiency syndrome

To explore the material foundation of kidney-yang-deficiency syndrome. Two kinds of rat models of deficiency of kidney-yang were induced by adenine intragastric administration (model I) and hydrocortisone intramuscular injection (model II). One hundred rats were randomly divided into normal control group, model I group, low-dose model II group, medium-dose model II group and high-dose model II group. After model establishment, contents of serum creatinine (SCr), blood urea nitrogen (BUN), and urine creatinine (UCr) were detected by automatic biochemistry analyzer; freezing point method was used for 24-hour urinary osmotic pressure (Uosm) testing and kaolinite method was used to detect the content of urinary 17-hydroxycorticosteroid (17-OHCS). Expression of aquaporin-1 in renal tissue was observed by using real time reverse transcription polymerase chain reaction. The rats of model groups had the characteristics of kidney-yang deficiency syndrome. The contents of SCr and BUN were significantly higher in model I group than in normal control group and three model II groups (P<0.05), and UCr and Uosm were significantly lower (P<0.05). The level of urinary 17-OHCS and expression of aquaporin-1 in renal tissue were decreased in the model I group (P<0.05) as compared with the normal control group. Compared with the normal control group, the content of SCr was increased and urinary 17-OHCS was decreased in the medium-dose model II group, but the expression of aquaporin-1 was increased in three model II groups with a dose-dependent manner. Aquaporin-1 may be one of the material foundations of kidney-yang-deficiency syndrome.

Measurements of freezing‐point depression to evaluate rubber network structure. Crosslinking of natural rubber with dicumyl peroxide

AbstractAn experimental approach based on the freezing‐point depression of a solvent in a swollen gel has been developed to characterize the structure of rubber networks. This property depends on the conditions required for the formation of crystalline nuclei, which are limited by the elastomer network restrictions. Information about the functionality, spatial distribution, and number of crosslinks can be obtained by the use of this easy and ready experimental method. Application of the tube model of rubber elasticity in the uniaxial stress–strain experiments of natural rubber samples vulcanized with dicumyl peroxide yields the characteristic parameters of the rubber networks, which are in concordance with the network structures predicted by the freezing point method. Finally influence of vulcanization conditions in network structure and its relationship with the mechanical properties was evaluated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 544–556, 2007

A near-infrared method for the assay of cineole in eucalyptus oil as an alternative to the official BP method.

Thirty different eucalyptus oil samples were scanned on the FOSS NIRSystems 6500 Rapid Content Sampler using a reflectance vessel as sample presentation method. The cineole content of each sample was determined by the BP method and these reference data were used to construct two calibration equations for cineole content in the oils using Vision software. The mean accuracy for the NIR method differed by 1.01% or less, and the mean bias by +/-0.33% or less, compared with the BP method. Calculation of the 95% confidence intervals for the slope and intercept of plots of NIR predicted values against BP method reference values showed that there was no evidence of fixed or relative systematic errors. Tests for short-term and intermediate repeatability were conducted. The standard deviation was 0.83% w/w or less and the coefficient of variation was 1.11% or less. The confidence intervals for both short-term and intermediate repeatability overlapped with that for the BP method, suggesting that there was no evidence for a difference in values obtained by the BP and NIR methods. The range of cineole contents used in the calibrations was extended by incorporating five samples of eucalyptus oil spiked with cineole, and five samples of two essential oils known to have a lower cineole content than eucalyptus oil, to give a range of 52.5 to 99.0% w/w. The mean accuracy decreased to an error of 1.26% or less and the bias to +/-0.50% or less. Again, confidence intervals suggested there was no evidence for fixed or systematic errors in the NIR calibrations. We propose that NIR spectroscopy could be used as an alternative method for the determination of cineole content in eucalyptus oils.

Volumetric and Cryoscopic Measurements of Aqueous [Co(en)3]3+ near 273 K

Osmotic coefficients of aqueous solutions of tris(ethylenediamine)cobalt(III) oxalate have been obtained from 0.000 to 0.010 mol-kg -1 by the freezing-point method. Apparent molar volumes have been determined by density measurements of aqueous solutions oftris(ethylenediamine)cobalt(III) perchlorate at 288 and 218 K in the range 0.000-0.060 mol-kg -1 . Partial molar volumes at infinite dilution for the complex cation at 288, 218, and 213 K are estimated

Multiphase equilibria of binary and ternary mixtures involving solid phase(s) at supercritical-fluid conditions

The P-T-liquid composition values of the solid-liquid-gas coexistence curves were determined for the binary systems naphthalene-ethylene and biphenyl-ethylene using the first freezing point method. The technique was further extended to the determination of the P and T values of the solid-solid-liquid gas equilibria for the systems naphthalene-biphenyl-CO 2 and naphthalene-phenanthrene-CO 2. The presence of a second solid increases the freezing point depression significantly, regardless of whether its triple point is higher or lower than that of the first solid. The results also indicate that the eutectic compositions of the binary solids may vary with pressure. The multiphase equilibria of both binary and ternary mixtures were correlated with some success by means of the Peng-Robinson (PR) equation together with the Adachi-Sugie mixing rule but with the α values of the PR equation reevaluated.

Osmotic coefficients of dilute aqueous solutions of unsymmetrical cobalt-amine type salts at 0�C

The osmotic coefficients of dilute aqueous solutions of [Co(pn)3]X3 [pn=1,2-diaminopropane and X=Cl−, Br− and (NO3)−] and [Co(tn)3]X3 (tn=1,3-diaminopropane and X=Cl− and Br−) have been measured from 0.00 to 0.02 mol-kg−1 at 0°C by the freezing point method. The results have been compared with those obtained from the numerical integration of the Poisson-Boltzmann equation.

Vapor pressure and freezing point osmolality measurements applied to a volatile screen.

This is a report of a rapid and precise screening procedure, developed for the determination of ethanol in serum using osmolality measurements. The osmolality of the patient is determined by freezing point method (freezing point osmometry) and dew point (water vapor pressure osmometry) method. The difference between freezing point osmolality and vapor pressure osmolality (delta osm) is due to the presence of volatiles in the serum, because the volatiles are not measured by vapor pressure osmometry. The amount of ethanol (mg/dL) in serum is estimated by multiplying delta osm by a factor of 4.2. As a comparison method, ethanol also is measured by a spectrophotometric alcohol dehydrogenase method. In addition, a significant difference between an osmometric alcohol assayed value and enzymatic spectrophotometric measurement indicates the presence of volatiles, other than ethanol. In addition to ethanol there is a linear relationship between osmolality and isopropanol or methanol when added in vitro to serum.

Osmolar relationships in infantile dehydration.

We studied serum osmolality in 167 consecutive infants admitted for gastroenteritis with 5% or more dehydration. Osmolality was determined by the freezing-point method in a 0.2-mL sample of serum immediately on admission. Forty-one patients (24.6%) had hypo-osmolar dehydration, with a mean osmolality of 257 mOsm/kg (range, 234 to 270 mOsm/kg). Eleven patients (6.5%) had hyperosmolar dehydration, with a mean osmolality of 329 mOsm/kg (range, 312 to 369 mOsm/kg). Simultaneous serum and CSF osmolalities were determined in 14 patients with hypo-osmolar and eight with hyperosmolar dehydration. In patients with hyperosmolar dehydration, serum osmolality correlated well with CSF osmolality, but a poor correlation was seen between serum and CSF sodium levels. Convulsions occurred in two patients in whom the CSF osmolality was greater than the serum osmolality by more than 10 mOsm/kg. Convulsions also occurred in two patients with hypo-osmolar dehydration in whom the CSF osmolality was lower than the serum osmolality by more than 13 mOsm/kg.

Osmotic concentrations: comparison of vapor pressure and freezing point methods.

Abstract The thermoelectric vapor pressure method of determining osmotic concentrations is inaccurate for certain classes of aqueous solutions and body fluids such as plasma. With temperatures of 25 ° to 50 °C., thermal decomposition of bicarbonates and volatilization of solutes may invalidate determinations by this method in contrast to that of cryoscopy. Other sources of discrepancy between these methods include chemical reactions with carbon dioxide, and the effect of temperature upon solute activities and solubilities. In general, the coefficient of variation is greater for vapor pressure than for freezing point measurements. For some aqueous solutions the vapor pressure method, carried out well above the freezing point, is more reliable than cryoscopy. A method is described for calculating changes in osmotic pressure resulting from chemical reactions in solution, and of following the course of these reactions by osmometric monitoring.

Displacement of Elastomers from Carbon Gel in Filled Mixes

Abstract Bound rubber may be displaced by milling filled hydrocarbon elastomers with polar rubbers such as NBR. The displacement is not complete in a single stage. Crosslinking can be detected in filled natural rubber by moderate swelling and then measuring the freezing point depression caused by the rubber in the filled and unfilled state, a greater depression being observed for the filled state. Filled and unfilled CB at the same concentration in benzene seems to cause the same freezing point depression and so crosslinking during the reinforcement of this rubber, though known to exist from other behavior, seems not to be indicated by the freezing point method.

Use of the freezing point method to adjust the tonicity of fixing solutions

It has been determined that many of the fixing solutions used in tissue preparation for electron microscopy are hypotonic, a few are hypertonic. A commercially available electronic apparatus is used to determine the freezing point depression of a given fixing solution. This solution is then adjusted by the addition of strong saline or water to yield a depression equivalent to that of 0.9 % NaCl. Such a fixative is called a normal saline equivalent (NSE) fixing solution. By use of this method an excellent OsO 4 and KMnO 4 fixing solution is formulated.

Isotonic Solutions XII: Permeability of Red Corpuscles to Various Water-Soluble Organic Iodine Compounds

In the present investigation, inquiry was made into the penetration effects of certain water-soluble organic iodine compounds with respect to the human erythrocyte membrane. Employing the hemolytic method, van't Hoff factors were calculated for each compound. The results indicated that all compounds studied yielded hemolytic i values which were higher than i values obtained by the freezing point method. Experiments were also conducted in the presence of 0.2% sodium chloride; in some cases this had the effect of lowering the hemolytic i values. Some tests were made in which the defibrinated blood used in determination of hemolytic i values was replaced by whole blood containing heparin sodium. The i values obtained with heparinized blood were in agreement with the i values resulting from the use of defibrinated blood. None of the compounds studied appeared to cause hemolysis of erythrocytes by penetration of the cell; hemolysis was noted only in hypotonic solutions of these compounds.

The effects of eserine on sodium regulation in crayfish

1. 1. The concentration of sodium in the blood of the crayfish, Orconectes virilis Hagen, is decreased from a mean value of 220 m. equiv/l. to 196 m. equiv/l. over a 24-hr period with the injection of eserine. This is accompanied by an increase in the total outflow of sodium into the medium. 2. 2. The concentration of sodium in the urine is drastically increased 3 hr after the injection of eserine with a partial return to normal at 12 hr. 3. 3. Control injections with water and sucrose cause no change in the concentration of sodium in the urine. 4. 4. Eserine injections caused an increase in the total osmotic concentrationas determined by the freezing point method. 5. 5. The data are discussed in light of evidence that the crayfish kidney is a filtration-reabsorption kidney, and that cholinesterase, found in both kidney and gills of crayfish, is involved in the regulation of sodium.

Determination of Isosmolar Blood Anticoagulant Solutions by the Freezing-Point Method

Abstract Freezing-point depressions of several anticoagulants were determined from which concentrations isosmolar with the blood of any species may be computed. The method is not applicable to solutes of high molecular weight.

The evaluation of cryoscopic constants for use in the determination of purity by the freezing point method

A simple modification to the apparatus used for the determination of freezing points enables cryoscopic constants to be evaluated. An accuracy of ±10% has been obtained with compounds having a latent heat of fusion greater than 14 Kcal/mole, and ±20% below this value. This is sufficiently accurate for most determinations of purity by the freezing point method.

The Freezing Point Method of Determining Free Energies in a 2-Component System Forming Compounds. Concentrated Aqueous Sulfuric Acid1

The Freezing Point Method of Determining Free Energies in a 2-Component System Forming Compounds. Concentrated Aqueous Sulfuric Acid¹