Average Diffusion Coefficient Values Research Articles

Chitosan/teff flour active films incorporated with citric acid and beetroot leaf extract: Physicochemical properties and mathematical modeling of phenolic release

Active compounds are integrated into food packaging films to enhance their food protection capabilities. Understanding the release of these components in films, particularly in crosslinking scenarios, is crucial. This study aimed to mathematically model the release of phenolic compounds from chitosan/teff flour films to understand how active compounds gradually release. Moreover, it was aimed to study the effects of incorporation of beetroot leaf extract and citric acid crosslinking. The collective observations, encompassing increased density and thermal stability, alongside concurrent reductions in moisture content, water solubility, water vapor permeability and swelling index following citric acid addition, strongly suggested the presence of crosslinking. Applying Fick's law and the finite element method revealed a substantial influence of the crosslinking agent on diffusion coefficients. The model exhibited strong agreement with experimental data, as reflected in low root mean square error values ranging from 3.02 to 8.50 mmol/m3 for films. Furthermore, the influence of citric acid crosslinking on the release of TPC was evident, as indicated by a decrease in average diffusion coefficient values from 3.499 × 10−13 m2 s−1 to 1.770 × 10−13 m2 s−1 with the formula with 1.5 % citric acid and 0.5 % beetroot leaf extract. This showcases the impact of various parameters on controlled release in food packaging.

MRI of wrist and diffusion tensor imaging of the median nerve in patients with carpal tunnel syndrome.

Diagnosis of carpal tunnel syndrome (CTS) is based on the clinical symptoms and nerve conduction study. Magnetic resonance imaging (MRI) is non-invasive objective tool for assessing the median nerve and carpal tunnel. The purpose of this study was to evaluate MRI changes in patients with CTS, and compare them with healthy subjects. Forty-three CTS patients and 43 age matched control were included and scanned in a 3T MRI scanner. Cross-sectional areas (CSA) of median nerve were measured at the level of distal radio-ulnar joint level (CSA1), proximal row of carpal bone (CSA2), and hook of hamate (CSA3). Flattening ratio (FR) of median nerve, thickness of flexor retinaculum, median nerve signal intensity, and thenar muscles were assessed. Fractional anisotropy (FA), average diffusion coefficient (ADC), and radial diffusivity (RD) of median nerve of CTS patients were obtained from diffusion tensor imaging (DTI) and compared with those of controls. Thirty-three patients (76.7%) were female. Mean duration of the pain was 7.4 ± 2.6 months. The mean CSA1 (13.2 ± 4.2 mm2), CSA2 (12.5 ± 3.5 mm2), and CSA3 (9.2 ± 1.5 mm2) in CTS patients were significantly higher compared to control group: CSA1 (10.15 ± 1.64 mm2), CSA2 (9.38 ± 1.37 mm2), and CSA3 (8.4 ± 0.9 mm2), (P = 0.001 in all). The mean FR of median nerve and thickness of flexor retinaculum were increased in CTS patients. The mean FA was reduced in CTS patients compared to control proximal to carpal tunnel and within the tunnel. Mean ADC and RD values were higher in CTS patients as compared to control for both levels. MRI can detect subtle changes in the median nerve and thenar muscles in CTS and may be useful in equivocal cases and to exclude secondary causes of CTS. DTI shows reduced FA and increased ADC and RD in CTS patients.

Cognitive and brain micro-structural correlates of alexithymia in essential tremor patients

Essential tremor (ET) is the most common movement disorder which has both motor and non-motor findings such as neuropsychiatic symptoms. Alexithymia is defined as inability to identify and describe emotions experienced by one's self or others. In our study, we aimed to evaluate the neurocognitive and brain micro-structural correlates of alexithymia in ET. 40 ET patients (mean age = 53.05 ± 19.74 years), were included. Fahn-Tolosa-Marin Tremor Rating Scale, Toronto Alexithymia Scale (TAS), Beck Depression Inventory, Beck Anxiety Inventory and detailed neurocognitive evaluation were applied to all patients. The patients were divided into three groups based on their TAS scores: no alexithymia, probable alexithymia, definite alexithymia. Diffusion Tensor Imaging (DTI) was performed in all patients. The mean TAS score was 50.05 ± 10.06. Depressive symptoms and anxiety levels were higher in definite alexithymia (p < 0.001, p < 0.01). Partial correlation controlling for age, gender and educational level between alexithymia scores and each cognitive test showed significant association between similarities (p < 0.001) and phonemic verbal fluency (p = 0.04). Left orbitofrontal cortex average diffusion coefficient (ADC) value (p = 0.05), left anterior cingulate cortex fractional anisotropy (FA) value (p = 0.04), right cuneus FA value (p = 0.04), left amygdala ADC value (p = 0.01) and left insula ADC value (p = 0.02) were differed between groups. TAS and DTImetrics were not found to be independently associated with the level of anxiety (p < 0.001) and depressive symptoms (p < 0.01). As a conclusion, impairments in executive function and complex attention were correlated with higher levels of alexithymia in ET. Many micro-structural alterations were determined to be correlated with alexithymia levels.

Evaluation of changes in magnetic resonance diffusion tensor imaging after treatment of delayed encephalopathy due to carbon monoxide poisoning.

Diffusion tensor imaging of the brain tissue microstructure was performed to predict or diagnose the pathophysiological mechanism underlying delayed encephalopathy after carbon monoxide poisoning and the treatment effect was analyzed. The changes in the diffusion parameters (average diffusion coefficient and fractional anisotropy) in adult patients after hyperbaric oxygen therapy of delayed encephalopathy after carbon monoxide poisoning were not significant differences of the two lateral ventricles or anterior or posterior limb of the internal capsule. In the group exposed to hyperbaric oxygen therapy, the fractional anisotropy values of the white matter in the ventricles of the brain and anterior and posterior limbs of the internal capsule were higher than those recorded before therapy, while the average diffusion coefficient values were significantly lower. These finding provide important monitoring indicators for clinicians.

Imaging diagnosis of 95 cases of moderate and severe acute carbon monoxide poisoning

Objective: To explore the difference of radiological imaging features of delayed encephalopathy after carbon monoxide poisoning (DECMP) and acute carbon monoxide poisoning (ACMP) , and the correlation between the imaging findings and clinical prognosis of the disease. Methods: The correlation between imaging findings and clinical manifestations and prognosis of 95 patients with moderate and severe acute carbon monoxide poisoning were retrospectively analyzed. In the above 95 cases, there were 62 cases of ACMP and 33 cases of DEACMP. All patients underwent conventional CT, MRI and magnetic resonance diffusion tensor imaging (DTI) . Circular regions of interest (ROI) measurement was used for analysis of average diffusion coefficient (ADC) value and fractional anisotropy (FA) value of the MRI and DTI imaging manifestations in different brain regions. Results: The main clinical manifestation of moderate acute carbon monoxide poisoning was consciousness disorder and fatigue; Severe poisoning patients showed deep coma as the main clinical manifestations; The most prominent clinical manifestations of DEACMP were mental disorders and neurological impairment in the extrapyramidal system. A total of 95 cases with moderate or severe CO poisoning showed unilateral or bilateral cerebral cortex, bilateral basal ganglia (white ball) , cerebral white matter around bilateral ventricles or bilateral centrum semiovale, around bilateral ventricles cerebral white matter around bilateral ventricles and bilateral centrum semiovale, cerebral cortex and subcortical involvement. CT showed normal or low density shadow.MRI showed that the lesion T(1)WI presented slightly low or equal signal, T(2)WI and FLAIR sequences showed equal, a slightly higher or high signal; DWI sequence showed slightly higher or high signal. ADC value and FA value in different brain white matter regions of DEACMP group was significantly lower than those of ACMP group (P<0.05) , especially for those around semi oval center and lateral ventricles of the brain white matter (P<0.01) ; The ADC values increased significantly, FA value decreased significantly in the nerve nucleus (P<0.05) , especially for ADC values in globus pallidus (P<0.01) . Conclusion: DTI can evaluate the brain tissue damage in patients with DEACMP more early and more accurately.

Diffusional behavior and guest conformational analysis of hexadecane-1,16-diol and hexadecane in urea crystal model via molecular dynamics simulation approach.

Diffusion at the atomic or molecular level is a source of many physical, chemical, and biological processes taking place in plentiful materials. This work is an endeavor toward investigating the diffusional behavior of two different type of guests, hexadecane-1,16-diol and hexadecane enclathration in urea tunnel architecture, whereby the correlation of the diffusion mechanism with the guest's structural and conformational properties is explored. To carry out this study, molecular dynamics simulation approach is adopted. It is found that hexadecane-1,16-diol exhibit slower diffusion with an average diffusion coefficient value [Formula: see text], where hexadecane diffuse more rapidly with an average diffusion coefficient value [Formula: see text]. It is also observed that the structural properties influence the guest's travel distance and torsion angle distribution of the trans and gauche conformational proportion. Furthermore, the observed high energy barrier accounted for hexadecane-1,16-diol and low energy barrier for hexadecane along urea tunnel systems was analyzed. The comparison of our obtained results are in close agreement with the available experimental measurements, i.e., gauche proportion properties between two different guest molecules correlate well with Raman spectroscopy investigation on α,ω-dihalogenoalkane/urea inclusion compounds. Our calculations also successfully endorse the structure-property relation between the two systems.

A technique for drug surrogate diffusion coefficient measurement by intravitreal injection

The aim of this work is to develop a technique to accurately measure the diffusion coefficient of drugs and drug surrogates in the vitreous humor using MRI. Fresh bovine eyes were used for drug diffusion study in the vitreous, and Gd-DTPA was chosen as a drug surrogate/contrast agent to visualize the diffusion process by MRI. Experiments were conducted by injecting 30μl of the Gd-DTPA with a concentration of 20mM/l in 0.9% saline in the vitreous of the whole bovine eye. MRI images were acquired at regular intervals for 1.5–2h, and Gd-DTPA concentration was determined from the MRI signal intensity. At each time point, concentration contours were constructed and a least-squares best fit to the corresponding theoretical contours, based on a cylindrical bolus model, was performed. The best fit at different time points resulted in fairly consistent diffusion coefficient values. With the surrogate injection technique perfected, highly-symmetric distribution of Gd-DTPA was observed, allowing for spherically symmetric mathematical models, with adjustments for ellipticity as needed, for the diffusion coefficient analysis. The analysis yielded an average diffusion coefficient value of (3.040±0.274)×10−6cm2/s. The 3-D MRI visualization together with careful symmetric injection of the surrogate/contrast agent has provided a quantitative tool for the accurate measurement of the diffusion coefficient. With symmetric injection and corresponding diffusion theory based on the point-source model with adjustments for nonzero bolus size and asymmetry, strong agreement of theory with experiments has been achieved.

Effect of ethanol on the transport of methylene blue through stratum corneum

Abstract Diffusion of methylene blue (MB) dissolved in both saline (0.9% NaCl) and 40% ethanol/saline in skin was investigated with reflectance spectroscopy. Experiments have been carried out with rat skin samples in vitro at 20 °C. The present studies have shown that 40% concentration of ethanol in solution greatly enhances transport of MB across stratum corneum. The diffusion coefficient of MB in skin in vitro has been estimated. The average value of diffusion coefficient is (2.2±0.9)×10 −6 cm 2 /s.

Diffusion Tensor Imaging Study of the Anterior Limb of Internal Capsules in Neuroleptic-Naive Schizophrenia

Abnormalities in brain structure have been implicated in psychosis. Herein, we investigated the differences in fractional anisotropy (FA) and average diffusion coefficient (ADC) in the bilateral anterior limb of internal capsules between neuroleptic-naive schizophrenic patients and appropriately matched healthy controls. Magnetic resonance imaging was performed with a 1.5 T superconductive MR scanner, and diffusion tensor imaging was carried out in 21 neuroleptic-naive schizophrenic patients and 18 matched healthy controls. FA and ADC were measured by region of interest analysis. Compared with healthy controls, the neuroleptic-naive schizophrenic patients showed significantly reduced FA in the bilateral anterior limb of the internal capsule. However, the difference in the ADC values between the patients and the controls was not significant. FA of the bilateral anterior limb of the internal capsule was reduced in neuroleptic-naive schizophrenic patients, indicating that the integrity of the white matter of the bilateral thalamus-frontal connection or the bilateral thalamus-anterior cingulate gyrus connection was destroyed.

Diffusion tensor trace mapping in normal adult brain using single-shot EPI technique. . A methodological study of the aging brain

To quantify age-related changes of the average diffusion coefficient value in normal adult brain using orientation-independent diffusion tensor trace mapping and to address the methodological influences on diffusion quantification. Fifty-four normal subjects (aged 20-79 years) were studied on a 1.5-T whole-body MR medical unit using a diffusion-weighted single-shot echo-planar imaging technique. Orientation-independent diffusion tensor trace maps were constructed for each subject using diffusion-weighted MR measurements in four different directions using a tetrahedral gradient combination pattern. The global average (including cerebral spinal fluid) and the tissue average of diffusion coefficients in adult brains were determined by analyzing the diffusion coefficient distribution histogram for the entire brain. Methodological influences on the measured diffusion coefficient were also investigated by comparing the results obtained using different experimental settings. Both global and tissue averages of the diffusion coefficient are significantly correlated with age (p<0.03). The global average of the diffusion coefficient increases 3% per decade after the age of 40, whereas the increase in the tissue average of diffusion coefficient is about 1% per decade. Experimental settings for self-diffusion measurements, such as data acquisition methods and number of b-values, can slightly influence the statistical distribution histogram of the diffusion tensor trace and its average value. Increased average diffusion coefficient in adult brains with aging are consistent with findings regarding structural changes in the brain that have been associated with aging. The study also demonstrates that it is desirable to use the same experimental parameters for diffusion coefficient quantification when comparing between different subjects and groups of interest.

Diffusion tensor trace mapping in normal adult brain using single-shot EPI technique. A methodological study of the aging brain.

To quantify age-related changes of the average diffusion coefficient value in normal adult brain using orientation-independent diffusion tensor trace mapping and to address the methodological influences on diffusion quantification. Fifty-four normal subjects (aged 20-79 years) were studied on a 1.5-T whole-body MR medical unit using a diffusion-weighted single-shot echo-planar imaging technique. Orientation-independent diffusion tensor trace maps were constructed for each subject using diffusion-weighted MR measurements in four different directions using a tetrahedral gradient combination pattern. The global average (including cerebral spinal fluid) and the tissue average of diffusion coefficients in adult brains were determined by analyzing the diffusion coefficient distribution histogram for the entire brain. Methodological influences on the measured diffusion coefficient were also investigated by comparing the results obtained using different experimental settings. Both global and tissue averages of the diffusion coefficient are significantly correlated with age (p<0.03). The global average of the diffusion coefficient increases 3% per decade after the age of 40, whereas the increase in the tissue average of diffusion coefficient is about 1% per decade. Experimental settings for self-diffusion measurements, such as data acquisition methods and number of b-values, can slightly influence the statistical distribution histogram of the diffusion tensor trace and its average value. Increased average diffusion coefficient in adult brains with aging are consistent with findings regarding structural changes in the brain that have been associated with aging. The study also demonstrates that it is desirable to use the same experimental parameters for diffusion coefficient quantification when comparing between different subjects and groups of interest.

Kinetic Analysis of PbTiO3 Phase Formation Via Diffusion Couple Method

ABSTRACTA detail kinetic analysis was performed on the PbTiO3 phase formation reaction occurring via PbO-TiO2 diffusion couple experiments. The diffusion model of Pb2+ and O2− ions was used to derive the kinetics equation of PbTiO3 phase formation reaction. From the parabolic kinetics between the thickness of PbTiO3 layer and time, the reaction rate constant for PbTiO3 formation was determined to be a function of the average diffusion coefficient of Pb2+ ions. By substituting the diffusion couple experimental results into the present kinetics equation, average diffusion coefficient values of Pb2+ ions in PbTiO3 layer were calculated according to temperature values. The activation energy value for the diffusion of Pb2+ ions was estimated for PbTiO3 formation using Arrhenius plot and the equation for the diffusion coefficient of Pb2+ ions was determined.

99mTc annexin V imaging of neonatal hypoxic brain injury.

Delayed cell loss in neonates after cerebral hypoxic-ischemic injury (HII) is believed to be a major cause of cerebral palsy. In this study, we used radiolabeled annexin V, a marker of delayed cell loss (apoptosis), to image neonatal rabbits suffering from HII. Twenty-two neonatal New Zealand White rabbits had ligation of the right common carotid artery with reduction of inspired oxygen concentration to induce HII. Experimental animals (n=17) were exposed to hypoxia until an ipsilateral hemispheric decrease in the average diffusion coefficient occurred. After reversal of hypoxia and normalization of average diffusion coefficient values, experimental animals were injected with (99m)Tc annexin V. Radionuclide images were recorded 2 hours later. Experimental animals showed no MR evidence of blood-brain barrier breakdown or perfusion abnormalities after hypoxia. Annexin images demonstrated multifocal brain uptake in both hemispheres of experimental but not control animals. Histology of the brains from experimental animals demonstrated scattered pyknotic cortical and hippocampal neurons with cytoplasmic vacuolization of glial cells without evidence of apoptotic nuclei by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining. Double staining with markers of cell type and exogenous annexin V revealed that annexin V was localized in the cytoplasm of scattered neurons and astrocytes in experimental and, less commonly, control brains in the presence of an intact blood-brain barrier. Apoptosis may develop after HII even in brains that appear normal on diffusion-weighted and perfusion MR. These data suggest a role of radiolabeled annexin V screening of neonates at risk for the development of cerebral palsy.

Kinetics analysis of mullite formation reaction at high temperatures

A detailed kinetics analysis was performed on the mullite (3Al 2O 3·2SiO 2) formation reaction occurring at high temperatures ranging from ∼1600 to 1800°C. The counterdiffusion model of Al 3+ and Si 4+ fluxes was used to derive the kinetics equation of the mullite formation reaction. From the parabolic kinetics between the thickness of the mullite layer and time, the reaction rate constant ( k) for the mullite formation was determined to be a function of the average diffusion coefficient of Si 4+ ions. This kinetics equation can be used to estimate the mullite formation at any temperature. By substituting previous experimental data into the present kinetics equation, average diffusion coefficient values of Si 4+ ions in the mullite layer were calculated and these values are in good agreement with the diffusion coefficient values calculated using Aksay’s interdiffusion equation for mullite formation. The activation energy values for the diffusion of the Si 4+ ions were estimated to range from 730 to 780 kJ/mol, which are close to those obtained from previous diffusion and creep experiments.

Assessment of induced rat mammary tumour response to chemotherapy using the apparent diffusion coefficient of tissue water as determined by diffusion-weighted1H-NMR spectroscopy in vivo

Chemosensitivity of N-methyl-N-nitrosourea-induced rat mammary tumours treated with 5-fluorouracil at a dose of 100 mg kg(-1) i.p. was assessed by using diffusion-weighted 1H-MRS to measure the average diffusion coefficient (ADC) of water in the tumour tissue. ADC measurements prior to any therapy correlated positively with necrotic fraction. Tumours with low initial ADC (< 0.95 x 10(9) m2 s(-1)) showed an increase in ADC 7 days after treatment, whereas tumours with a high initial ADC (> 1.2 x 10(9) m2 s(-1)) showed a decrease. All tumours decreased significantly in volume (P < 0.05) 2, 5 and 7 days after treatment. At day 7 post-treatment, tumours with a high pre-treatment ADC started to regrow. The initial ADC value, as well as changes after treatment predict tumour chemosensitivity, which could be clinically relevant.

Assessment of induced rat mammary tumour response to chemotherapy using the apparent diffusion coefficient of tissue water as determined by diffusion-weighted 1H-NMR spectroscopy in vivo

Chemosensitivity of N-methyl-N-nitrosourea-induced rat mammary tumours treated with 5-fluorouracil at a dose of 100 mg kg−1 i.p. was assessed by using diffusion-weighted 1H-MRS to measure the average diffusion coefficient (ADC) of water in the tumour tissue. ADC measurements prior to any therapy correlated positively with necrotic fraction. Tumours with low initial ADC (<0.95×109 m2 s−1) showed an increase in ADC 7 days after treatment, whereas tumours with a high initial ADC (>1.2×109 m2 s−1) showed a decrease. All tumours decreased significantly in volume (P<0.05) 2, 5 and 7 days after treatment. At day 7 post-treatment, tumours with a high pre-treatment ADC started to regrow. The initial ADC value, as well as changes after treatment predict tumour chemosensitivity, which could be clinically relevant.

DETERMINATION OF DIFFUSION COEFFICIENT OF THE TURKISH TRONA IN WATER

Mineral Resources EngineeringVol. 05, No. 01, pp. 3-11 (1996) No AccessDETERMINATION OF DIFFUSION COEFFICIENT OF THE TURKISH TRONA IN WATERGÜLHAYAT NASÜN-SAYGILI and HASANCAN OKUTANGÜLHAYAT NASÜN-SAYGILIIstanbul Technical University, Chemical and Metallurgical Engineering Faculty, Chemical Engineering Department, 80626, Maslak-Istanbul, Turkey Search for more papers by this author and HASANCAN OKUTANIstanbul Technical University, Chemical and Metallurgical Engineering Faculty, Chemical Engineering Department, 80626, Maslak-Istanbul, Turkey Search for more papers by this author https://doi.org/10.1142/S0950609896000029Cited by:1 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail AbstractLaboratory experiments were conducted to measure the diffusion coefficient of the Turkish trona in water. A rapid and inexpensive method was used for measuring the diffusion coefficient. The procedure consists essentially of soaking a porous disc in the solution of interest and then suspending the disc over a bath of pure water. The rate of diffusion of trona solution from the disc is then ascertained by measuring the apparent weight of the suspended disc at various times. The rate of change of the apparent weight is directly related to the loss of solute and hence to the diffusion coefficient of the trona. The diffusion coefficient of trona from solutions of various concentrations was measured and a linear relationship was found between diffusion coefficient and trona solution concentration. The average value of diffusion coefficient of trona was calculated to be 1.194 10−5 cm2/sec at 25°C. FiguresReferencesRelatedDetailsCited By 1Effect of temperature on dissolution of Turkish tronaGülhayat Nasün-Saygılı1 Feb 2003 | Hydrometallurgy, Vol. 68, No. 1-3 Recommended Vol. 05, No. 01 Metrics History PDF download

Soil moisture movement and groundwater recharge by tritium tracer tagging technique

The paper deals with the study of rate of soil moisture movement and recharge to groundwater system at Indian Agricultural Research Institute (IARI) farm for the years 1973, 1974 and 1975. The utility of artificially injected tritium, experimental techniques adopted and a quantitative determination of recharge and moisture movement rates are discussed. Corrections for upward movement of moisture after the end of monsoon have been used to calculate the average rates of water movement below the injection level and groundwater recharge. Average rates of soil moisture movement and recharge are 9.4 mm/d and 27.4% (193 mm) of monsoon precipitation for three years respectively. Under favourable conditions the diffusion coefficients for soil water system are calculated assuming Gaussian distribution of tritium concentrations in the soil profiles. The average value of diffusion coefficient is 2.5 × 10−5 cm2/s for the sandy loam soils. The variation in recharge is mainly due to inherent variability in soil physical properties and vegetative cover. The technique is not found reliable for higher water table conditions on account of lateral flow.