DIELECTRIC AND ELECTRICAL BEHAVIOUR OF ZNO AND CDO SEMICONDUCTING MATERIALS WITH AND WITHOUT MN DOPING

ZnO and CdO pellets with and without Mn doping were prepared by using Hydraulic pressure machine at room temperature. The effect of Mn content (1,3,5 wt % ) on the electrical properties have been carried out by Keithley meter. The result shows that the resistivity decreases as increasing Mn content. Impedance analyzer are used for dielectric behavior and results shows that decrement of dielectric constant as well as dielectric loss with the increment of frequency

Study on the improvement of image quality of 3.0 T fetal head MR scan by high dielectric constant / 中华放射学杂志

Objective:To explore the clinical application of a new high dielectric constant (HDC) to improve image quality in 3.0 T fetal head MR scans.Methods:Forty pregnant women who underwent 3.0 T fetal head MR examinations at the Drum Tower Hospital of Nanjing University School of Medicine from May to July 2021 were prospectively included and divided into a test group and a control group according to the placement and non-placement of HDC pads. After the scans were completed, qualitative and quantitative analysis were performed on the image quality of the two groups acquired in each case. Qualitative analysis: A 5-point scale was used to score the images of both groups by two diagnosticians and their scores were recorded. Quantitative analysis: Firstly, the overall radiofrequency specific absorption ratio (SAR) values of the two sets of fetal cranial cross-sectional scans of each pregnant woman were recorded separately, and the average rate of change of the overall SAR values was calculated; secondly, four regions of interest (ROIs) were placed on the standard level of the cross-sectional section of each fetal cranium (including the level of the basal ganglia region of the dorsal thalamus), and the minimum and maximum of the four ROIs of each of the two data sets were calculated separately. The ratio of minimum to maximum signal intensity (RSI), signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated for each of the four ROIs in the two sets of data. Wilcoxon test was used to analyze the differences between the two groups of image quality score results; paired sample t-test or paired rank sum test was used to analyze the differences in SAR, RSI, SNR and CNR values between the two groups. Results:The fetal head image quality score was 4 (3, 4) in the test group and 3 (1, 4) in the control group, and the test group was significantly higher than the control group, with statistically significant difference ( Z=-3.62, P<0.01), and the images in the test group had a uniform signal compared with the control group, and none of them had significant artifacts. The results of quantitative analysis showed that the overall SAR value of the test group was significantly reduced, with a mean reduction rate of 32.1%, and the difference between the SAR values of the two groups was statistically significant ( Z=-2.78, P<0.01). The RSI, SNR and CNR in the frontal, temporal, thalamic and occipital lobes of the test group were all higher than those of the control group, and the differences were all statistically significant ( P<0.01). Conclusion:The HDC pads can significantly improve the image quality of 3.0 T fetal head imaging by reducing or eliminating the inhomogeneous artifacts in the RF field, which makes a good technical foundation for fetal head MR imaging.

Measurement of local tissue water in the diagnosis of breast cancer related lymphedema / 中华整形外科杂志

Objective@#To investigate the value of local tissue water (LTW) in the diagnosis and evaluation for breast cancer related lymphedema(BCRL).@*Methods@#Sixty one patients with BCRL in Peking Union Medical College Hospital were recruited. The tissue dielectric constant (TDC) method was used to measure the LTW of the ventral and dorsal midpoint of the bilateral upper arm and forearm of the patients. Meanwhile, the circumference of the bilateral upper arm and forearm was measured with a tape. The LTW ratio and the circumference ratio of the affected and the unaffected arms were calculated respectively.@*Results@#The percentage of the patients who had two centimeter or above difference in the same reference point between their affected and unaffected arms or had 1.2 or above LTW ratio in their ventral upper arm and forearm were 29.5%, 39.3% and 52.5% respectively. The LTW ratio of the ventral reference point between the affected arms and the unaffected arms was significantly higher than that of the dorsal reference point (P<0.05). The circumference ratio was related to the LTW ratio between the affected arms and the unaffected arms (P<0.05), especially the coefficient of the ventral LTW ratio was higher. The lymphedema stage of the patients was also related to the LTW ratio of the upper arm and forearm (P<0.05), and the coefficient of the LTW ratio in the ventral forearm was the highest.@*Conclusions@#LTW measurement is helpful for early diagnosis and quantitative evaluation of BCRL. It is suggested that the ventral reference point of forearm should be examined.

Effect of ultrahigh diluted homeopathic medicines on the electrical properties of PVDF-HFP

In an effort to improve the electrical properties of the electroactive Poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP), we introduced a novel and simple approach to synthesize PVDFHFP composite films by incorporating ultrahigh dilutions of two homeopathic medicines Ferrum metallicum (FM) and Zincum oxidatum (ZO) in different potencies. The homeo-PVDF-composite films (HPCF) were synthesized by simple solution casting technique. XRD, FESEM, FTIR studies were performed to check the presence of nanoparticles in the film. The electrical properties of the HPCF samples get enhanced significantly due to the incorporation of the medicines and the effect increases with the increase in potency of the medicines.

Condição de contorno para calibração de reflectômetro usado para medição de água no solo / Boundary conditions for calibration of reflectometer used to measure soil water

A reflectometria no domínio do tempo (TDR, na sigla em inglês) é uma técnica indireta usada para estimar o conteúdo de água do solo (θ) em função de sua constante dielétrica aparente (Ka). Neste estudo, o objetivo principal foi investigar as consequências de se incluir ou não medidas de Ka em água, na elaboração da curva de calibração do TDR. Foram avaliados horizontes de solo com 0,13kg kg-1, 0,23kg kg-1 e 0,64kg kg-1de argila. Para cada horizonte, a Ka foi medida em amostras desde solo seco até solo saturado. Adicionalmente, a Ka foi medida apenas em água. As medições foram feitas usando-se cabos coaxiais RGC58, 50 Ohm e sensor dupla haste metálica de 19cm. Para cada horizonte, foram formados dois conjuntos de dados com θ e Ka, um com e outro sem as medidas de Ka em água. Em cada conjunto, foi ajustada uma equação polinomial de terceiro grau, estimando θ em função de Ka. Com a inclusão das medidas de Ka em água, o polinômio de terceiro grau se ajustou melhor ao extremo saturado e preveniu erros na estimativa de θ. Como não há garantia de que as medidas de Ka de campo não serão maiores que as medidas de Ka das amostras saturadas em laboratório, recomenda-se a inclusão de medidas de Ka em água para obtenção da curva de calibração. Sem esse procedimento e sem verificação de campo das medidas de Ka, erros na estimativa de θ da ordem de 0,1m3 m-3 podem ocorrer facilmente.

The time domain reflectometry is a technique used to estimate soil water content (θ) as a function of its apparent dielectric constant (Ka). In this study the main objective was to investigate the consequences of including or not measures of Ka in water on the TDR calibration curve. Three horizons with different clay content were used: 0.13kg kg-1, 0.23kg kg-1 and 0.64kg kg-1. In each horizon, Ka was measured from dry to saturated soil. Additionally, Ka was measured in water. Measurements were made ​​using coaxial cables RGC58, 50 ohms and double stainless rod of 19cm. For each soil two data sets with θ and Ka were formed, one with and another without the addition of Ka measured in water. In each set a cubic polynomial equation was adjusted, estimating θ as a function of Ka. With the inclusion of Ka measured in water the cubic polynomial adjusted better the extreme saturated and avoided errors in the estimated θ. Since there is no certainty that the measures of Ka on field will not be greater than the measures of Ka in the saturated samples in the laboratory, it's recommend to include measures of Ka in water to obtain the calibration curve. Without this procedure and no field verification of Ka measurements, errors in estimated θ of the order of 0.1m3 m-3 can easily occur.

Crystallization separation of antitumor constituent 20(R)-25-OCH3-PPD / 中草药

Objective: To separate antitumor constituent AD-1 [20(R)-25-OCH3-protopanoxadiol (PPD)] from non-racemic enatiomeric mixture. Methods: A crystallization method has been developed to separate AD-1 from 25-OCH3-PPD non-racemic enatiomeric mixture, the sorts and amount of solvent and crystallization temperature were optimized to obtain the best separative conditions, and the relationship between the S/R percentage of 25-OCH3-PPD non-racemic enantiomeric mixture and dielectric constant of the solvent was discussed. Results: Under the optimized conditions (acetone 26 mL, 4°C), the yield and purity of AD-1 crystals are 38.76% and 97.83% from 25-OCH3-PPD non-racemic enatiomeric mixture (R: 59.34%; S: 38.35%), respectively. Conclusion: The ε values of solvents are about 20.7, and an unsaturated solution and low temperature are beneficial to the separation of AD-1 from 25-OCH3-PPD non-racemic enatiomeric mixture.

Dielectric studies of wheat in powder form at microwave frequencies.

Dielectric constant and loss factor of Raj-4120 variety of Indian wheat were determined in powder form (grain size 125 to 150 ) at room temperature. Microwaves at three different frequencies were employed in C-band, X-band and Ku-band respectively for investigating frequency dependence of dielectric parameters of the sample. Bulk dielectric values of the sample were determined by employing the dielectric mixture relations, such as, half power mixture equation, Landau and Lifshitz, Looyenga equation etc.

An Investigation on the Vibrational Frequency of C=O Bond in Benzoic Acid / 第三军医大学学报

The infrared spectra of benzoic acid in its solid form and in various solvents were determined.The result confirmed that the carbonyl bond of the dimer form of benzoic acid occurs at 1694 cm~(-l),but not at 1653 cm~(-1).The influences of hydrogen bond (polar solvent) and solvent effect (nonpolar solvent) on the vibrational frequency of C=O bond was also studied.In the nonpolar solvent,owing to the increment of the dielectric constant (?) of the solvent,C=O stretching frequency decreases slightly and the relationship between them can be expressed with the following formula:Here K and C are two contants,V_v and V_s represent the vibrational frequencyof C=O bond of benzoic acid in vapor and in solvent respectively.