Shelf-life of99mTc(Sn)-pyrophosphate

The effect of the preparation conditions on the in vitro stability of^99mTc (Sn)-pyrophosphate kit solution has been examined. To extend the shelf-life of the preparation, different methods of protection were tested. Nitrogen purging stabilizes the kit for at least 6 h after labeling when the content of^99mTc-pertechnetate raises to about 5%. However, this method is ineffective in the presence of hydrogen peroxide. The protecting ability of two chemicals was also determined. Gentisic acid gave good results. In the presence of 50 g of gentisic acid per ml of the kit the content of pertechnetate was 1–2% throughout the examined time interval. To eliminate the influence of hydrogen peroxide (6 g per ml of the kit) about 100 g of gentisic acid is needed. N, N-diphenyl-p-phenylenediamine (DPPD) performs some protecting effect only when used in the samples protected by nitrogen purging. However its protecting ability is lower that in the case of gentisic acid.     

Statistical approach to bistable behaviour of a nonlinear system in a stationary field

Conclusions This discussion concerning the probability density confirms in a new way the results obtained in paper [1] in which a two-peak behaviour of the photocount distribution has been found. This general result depends on the particular nonlinear interaction scheme, and the bistable behaviour is caused by quantum fluctuations produced by the nonlinear interaction.As losses are not taken into account, other kinds of fluctuations that can modify the bistable behaviour are not accounted for in this paper.     

Toward the synthesis of reidispongiolide a: stereocontrolled synthesis of the C17-C22 and C23-C35 degradation fragments

[structure: see text] By relying on the asymmetric aldol reactions of chiral ketones, a highly stereocontrolled synthesis of each of the C(17)-C(22) and C(23)-C(35) degradation fragments of reidispongiolide A has been achieved. This permits a configurational assignment of the complete C(17)-C(36) region of this antimitotic macrolide, along with providing advanced intermediates for a projected total synthesis.     

Cyclization of citronellal in a supercritical solvent in a flow reactor in the presence of Al2O3

The reactivity of citronellal under supercritical solvent conditions in a flow reactor in the presence of Al₂O₃ is examined. It is shown that at 160°C, the main transformation product of citronellal is isopulegol, and when the temperature is increased to 190°C, they are monoterpenes with a para-menthane framework and myrcene.     

Optimal volume-corrected laplace-metropolis method

The article provides a refinement for the volume-corrected Laplace-Metropolis estimator of the marginal likelihood of DiCiccioet al. The correction volume of probability α in DiCiccioet al. is fixed and suggested to take the value α=0.05. In this article α is selected based on an asymptotic analysis to minimize the mean square relative error (MSRE). This optimal choice of α is shown to be invariant under linear transformations. The invariance property leads to easy implementation for multivariate problems. An implementation procedure is provided for practical use. A simulation study and a real data example are presented.     

Hepatic lipid composition analysis using 3.0-T MR spectroscopy in a steatotic rat model

Purpose

To investigate the feasibility of in vivo assessment of hepatic lipid composition using 3.0-T proton magnetic resonance spectroscopy (¹H-MRS) in a steatotic rat model and compare it to histopathological and biochemical assessment.

Materials and Methods

Hepatic steatosis was induced by feeding rats with a methionine/choline-deficient (MCD) diet for 1, 2, 3, 5 or 7 weeks (n=5 per group). At the end of the diet period, ¹H-MRS of the liver was performed, and rats were sacrificed for histopathological and biochemical assessment of the liver. Spectra were acquired in a single voxel (1.2 cc) using a point-resolved spectroscopic sequence with TE/TR=35/2000 ms and 64 signal acquisitions. From the MR spectra, peak area ratios were calculated to estimate hepatic lipid composition.

Results

During MCD diet periods, hepatic steatosis significantly increased on histopathology (P<.001). The ¹H-MRS measurements of total hepatic fat content [1.3/(1.3+4.65) ppm] correlated strongly with histological macrovesicular hepatic steatosis (r=0.93, P<.001) and with the biochemical total hepatic fatty acids (r=0.94, P<.001). Total unsaturated fatty acids [TUFA, 5.4/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with the biochemical unsaturated fatty acids (r=0.90, P<.001). Polyunsaturated fatty acids [PUFA, 2.8/(1.3+4.65) ppm] estimated with ¹H-MRS strongly correlated with biochemical PUFA (r=0.91, P<.001). The proportion of total unsaturated fatty acids relative to the amount of total fatty acids (rTUFA, 5.4/1.3ppm) measured with ¹H-MRS strongly correlated with the biochemical amount of unsaturated relative to total hepatic fatty acids (r=0.81, P<.001). The proportion of PUFA relative to the amount of total fatty acids (rPUFA, 2.8/1.3 ppm) measured with ¹H-MRS correlated with the biochemical amount of PUFA relative to total fatty acids (r=0.59, P=0.005,) and with the biochemical amount of omega-6 PUFA relative to total fatty acids (r=0.73, P<.001).PUFA at ¹H-MRS correlated with the histopathologically assessed degree of lobular inflammation in the liver (r=0.57, P=.001).

Conclusion

3.0T ¹H-MRS is able to measure poly- and unsaturated hepatic fatty acids and this strongly correlates with biochemical assessment. This study provides evidence that 3.0-T ¹H-MRS is a noninvasive technique to assess hepatic lipid composition.     

Mechanisms determining the salience of coloration in echoed sound: influence of interaural time and level differences

This study investigates whether the salience of the pitch associated with a single reflection of a broadband sound, such as noise, is determined by the monaural information mediated by the stimuli at the two ears, or by the relative locations of the primary sound and the reflection. Pitch strength was measured as a function of the reflection delay and the lateral displacement between the primary sound and the reflection. Thereby, lateral displacement was produced by means of interaural time differences (ITDs) in experiment 1 and interaural level differences (ILDs) in experiment 3. The results from both experiments are in accordance with the assumption that the strength of the pitch associated with a reflection is based on a central average of the internal representations of the stimuli at the two ears. This notion was corroborated by experiment 2, which showed that the results from experiment 1 could be mimicked by simply adding the stimuli from the two ears and presenting the merged stimulus identically to both ears.     

Transmissive in-fiber Fabry-Perot etalons as tunable dispersion compensators and dispersion-slope compensators

We report for what is believed to be the first time the use of transmissive fiber Bragg grating-based Fabry-Perot etalons for tunable dispersion compensation and dispersion-slope compensation. The resulting device has a number of advantages, such as low cost, ease of fabrication, full optical fiber compatibility, and simplicity.     

Unilateral recurrent laryngeal nerve paralysis:The importance of “preoperative” voice therapy

This preliminary retrospective study of 19 female patients and 22male patients with unilateral recurrent nerve lesions demonstrated the promise of objective measurements in predicting the need for surgery, the efficacy of voice therapy in ameliorating vocal symptoms, and the effects of therapy in conjunction with surgery. Sixty-eight percent (68%) of the female patients and 64% of the male patients did not elect to have surgery. Outcome satisfaction of nonsurgical and surgical patients appeared to be similar. The data from this study support the importance of preoperative therapy for patients with unilateral vocal fold paralysis.     

Optodynamic description of a linear momentum transfer from a laser induced ultrasonic wave to a rod

We present a new optodynamic experimental technique to measure the linear momentum obtained by a rod during a nanosecond laser pulse ablation of the rod’s front face on the basis of the displacement due to an ultrasonic wave reflection at its rear end. With the help of a simple theory, we explained the step-like motion of the rod’s free end. This theory conforms well with the general shape of the measured displacement history curve. The acquired momentum can be directly estimated by measuring the height of a step from the step-like motion of the rod’s end. Measurements based on an arm-compensated Michelson interferometer also enabled us to follow the attenuation of an ultrasonic wave and so to determine the characteristic attenuation time. This quantity plays a major role in the transfer of linear momentum from within the initial ultrasonic wave to the final net uniform motion of the specimen. PACS  52.38.Mf; 43.35.Yb; 43.35.Cg