Cerebral energy metabolism in rats studied by phosphorus nuclear magnetic resonance using surface coils

Phosphorus nuclear magnetic resonance with surface coils was used to investigate the regional metabolism of the rat brain in vivo under conditions of normoxia, severe hypoxemia, partial necrosis, and partial ischemia. The results show an increase in sugar phosphate and/or inorganic phosphate with injury in accordance with in vivo assays. The technique provides a powerful means of monitoring the metabolism of stroke and its response to therapy in vivo.     

Ultrasonic treatment decreases Lyophyllum decastes fruiting body browning and affects energy metabolism

Lyophyllum decastes is a common mushroom that is prone to browning during prolonged storage. In this study, the effects of ultrasonic treatment on metabolic gene expression, enzyme activity, and metabolic compounds related to L. decastes browning were investigated. Treatment of the fruiting body at 35 kHz and 300 W for 10 min reduced the browning index of L. decastes by 21.0 % and increased the L* value by 11.1 %. Ultrasonic treatment of the fruiting body resulted in higher levels of total phenols, flavonoids, and 9 kinds of amino acid with catalase (CAT) and peroxidase (POD) activities maintained at high levels. Higher cytochrome c oxidase (CCO), succinate dehydrogenase (SDH), phosphofructokinase (PFK), and pyruvate kinase (PK) activities may be ascribed to increased antioxidant capacity. Moreover, ultrasonication retained higher adenosine triphosphate (ATP) concentrations with an increased energy charge, while there were lower levels of adenosine diphosphate (ADP) and reduced and oxidized nicotinamide adenine dinucleotide (NADH and NAD⁺), respectively. Meanwhile, lower lignin contents were observed, along with retarded polyphenol oxidase (PPO) and lipoxygenase (LOX) activities. Lower PPO activity reduced the fruiting body enzymatic browning rate through decreased expression of LdPpo1, LdPpo2, and LdPpo3 during storage at 4 °C for 16 days. This activity may be used to determine the effectiveness of ultrasonication.     

Analysis of thermal energy harvesting using ferromagnetic materials

This Letter aims at giving a preliminary investigation of the thermal energy harvesting capabilities of a technique using the temperature-dependent permeability of ferromagnetic materials. The principles lie in the modification of the magnetic field caused by the variation of the permeability due to the temperature change, hence generating a voltage across a coil surrounding the circuit. The technique can be made truly passive by the use of magnets for applying bias magnetic field. Theoretical results, validated by experimental measurements, show a voltage output of 1.2 mV at optimal load of 2 Ω under 60 K temperature variation in 5 s (with a maximum slope of 25 K s⁻¹). Further improvements, such as the use of low resistivity coil and magnet with high remnant magnetic field, indicate that it is possible to convert up to 7.35 μJ cm⁻³ K⁻² cycle⁻¹.     

Electrostatic energy harvesting enhancement using variable equivalent permittivity

This Letter exposes an electrostatic-based vibration energy scavenging scheme using a two-layer configuration made of a high permittivity material and a low permittivity layer of variable thickness. Because of the significant change in the permittivity allowed by this process, the capacitance ratio variation is much larger than in the case of a single layer (whatever the permittivity of the latter), therefore allowing an increased efficiency and a significant energy gain, by a typical factor of 50.     

Post mortem energy metabolism and pH development in porcine M. longissimus dorsi as affected by two different cooling regimes. A (31)P-NMR spectroscopic study

(31)P-NMR spectroscopy was carried out on M. longissimus dorsi samples chilled by two different cooling profiles corresponding to commercial batch and tunnel chilling. The half-life of post mortem phosphocreatine (PCr) degradation was found to be significantly less in muscle samples exposed to tunnel chilling (rapid) compared with muscle samples exposed to batch chilling (soft) conditions, while no difference in the post mortem ATP degradation was found. Moreover, the post mortem pH development in the muscle samples differed considerably between the two cooling regimes. A maximum difference of approx. 0.25 pH units between the two cooling profiles was observed around 150 min post mortem. Theoretical calculations of the registered pH difference between rapid and soft chilling of muscle samples revealed that the temperature effect on the buffer capacity of muscle is the major determining factor in the detected difference in intracellular pH between the two cooling profiles, while any contribution from a temperature-induced delayed progress in the lactate formation post mortem seems negligible. Moreover, calculations on the effect of the registered pH difference between rapid and soft chilling of muscle samples resemble a 2.5 times greater denaturation of myosin in samples which were chilled softly compared with samples chilled more rapidly. Finally, the relationship to the functionality of meats from soft and rapid chilled pork carcasses is discussed.     

Langendorff灌流心脏的31P NMR谱测定

测定了Langendorff灌流大鼠和兔心脏的³¹P NMR谱.观测到PCr、ATP、SP、P_i以及PME和GPC等含磷代谢物的共振峰,各谱峰之间实现了很好的分辨.在3~5min的累加时间内测得的图谱具有较好的S/N,可用于以上含磷代谢物的定量测定,以高能含磷化合物ATP和PCr相对峰强度以及冠脉流量的变化对灌流大鼠心脏代谢的稳定性进行了考察,结果表明,在本实验条件下大鼠心脏的能量储存至少可稳定2h,用所建方法以3min的时间间隔对同一大鼠心脏缺血21min及再灌注12min过程中心脏的³¹P NMR谱进行了连续跟踪测定,并初步观测了缺血及再灌注过程中心肌细胞内ATP、PCr与P_i之间的消长关系.     

Anoxia followed by hyperoxia: In vivo 31-P NMR of cat brain

In vivo ³¹P NMR spectroscopy was performed on a cat brain subjected to an extended period of anoxia followed by restoration of oxygen. High energy phosphate spectra were continuously obtained and pH measured. Following the onset of anoxia, phosphocreatine and ATP peaks decreased with a concomitant increase in inorganic phosphate. Following 34 min ventilation on 100% N₂, the animal was ventilated on 100% O₂. The spectral content progressively changed, inorganic phosphate decreased and ATP increased with the spectrum closely resembling that of control. Our results suggest that the absence of NMR detectable ATP signal cannot be interpreted as an irreversable change in cellular metabolic function.     

Assessment of tumor vasculature for diagnostic and therapeutic applications in a mouse model in vivo using 25-MHz power Doppler imaging

Objective

The blood flow rate in the microcirculation associated with angiogenesis plays an important role in the progression and treatment of cancer. Since the microvascular status of tumor vessels can yield useful clinical information, assessing changes in the tumor microcirculation could be particularly helpful for tumor evaluation and treatment planning.

Methods

In this study we used a self-developed 25-MHz ultrasound imaging system with a spatial resolution of 150 μm for assessing tumor-microcirculation development and the pattern of the vasculature in three tumor-bearing mice in vivo based on power Doppler images. The total Doppler power (DP) and color pixel density (CPD) revealed the presence of functional vessels distributed throughout a tumor volume. The vasculature distributions in the core and periphery were compared to the regulation of vasculature function, which facilitated determination of when the tumor grew rapidly.

Results

The data obtained from a quantified analysis of power Doppler images indicated that the tumor vascularity initially increased throughout the tumor. Both DP and CPD increased rapidly in the tumor periphery when the tumor volume exceeded 10 mm³.

Conclusion

Our preclinical findings suggest that power Doppler imaging could be useful for detecting the changes in tumor vascular perfusion and for determining the optimal treatment timing when a tumor begins its rapid volumetric growth.     

Enhancement of image quality by using metamaterial inspired energy harvester

Metamaterial energy harvester based subwavelength imaging structure is presented. Besides, 2×2 array patch antenna is designed to create incident radiated signal towards the proposed harvester structure. Harvested energy is converted to DC voltage signal by using Schottky diodes and each cell is represented by 256 grey levelled pixel value. Therefore, any incident electromagnetic wave placed in the operating frequency range can be monitorized. In the experimental study, experiments are realized with and without antenna to investigate the effects of instantaneous electromagnetic waves and the observed images. Afterwards, another experiment is conducted to observe the effects of metal plate which is located between the antenna and the harvester structure. The last experiment is performed by using a Yagi Uda antenna for sub-wavelength imaging. The proposed harvester structure can be used in various applications such as energy harvesting, incident wave tracing, crack detection, spy device detection, medical imaging, and so on.     

同核双原子分子离子的势能研究

使用作者最近建立的研究双原子分子离子精确势能的离子能量自洽法(ECMI),对碱金属、氟、氧的同核双原子分子离子的以下电子态进行了研究:Na2 的X2∑g 态,Li2 的X2∏u态,F2 的A2Пu态,F2 的X2∏g,和O2 的A2∏u态.将获得的ECMI势能曲线与用其他理论方法得到的势能曲线进行的比较表明,ECMI得到了这些态的最好势能,而且ECMI势不仅能获得平衡核间距附近的精确势能,还能得到其他方法往往难以得到的双原子分子离子渐进区和离解区的正确势能.     

31P-NMR分析湿地沉积物有机磷的方法优化

近年来,31P-NMR（nuclearmagneticresonance）已成为研究环境有机磷的有力武器,然而此方法在湿地学研究中的应用却很少,关于湿地沉积物样品制备方法的研究更缺乏。本研究通过改变提取剂组成、提取剂比例、离心条件、检测扫描时间等因素设计实验,寻找最佳的湿地沉积物样品处理及检测方法,以期为31P-NMR技术在湿地沉积物样品有机磷研究中的应用提供科学依据。结果表明采用：1mol·L-1HCl预提取,0.25mol·L-1NaOH＋0.05mol·L-1EDTA主提取,沉积物与提取剂比例为1∶8的提取方法,可获得更好的提取效果。提取完成后,采用冷冻高速离心可更好地分离提取液、避免某些磷组分的水解。此外,NMR扫描分析时间设为14～16h（约扫描25000次）可获得更完整的图谱。相较于传统的化学分析法,31P-NMR法的样品前处理相对简单、分析时破坏性小且组分分辨完全,该技术的运用,有望获得湿地磷循环,特别是对有机磷认知的新突破。     

离体心脏的31P NMR谱

³¹P NMR谱自70年代后期开始被用于离体心脏中含磷化合物代谢的动态研究.^3lP NMR谱不仅可以鉴定心肌组织中浓度较高的含磷化合物,即ATP、磷酸肌酸和无机磷酸盐,而且可提供有关这些化合物化学环境(包括pH和Mg²⁺)和细胞内分布的信息.利用这一非损伤性的定量分析方法,可连续观测心肌的代谢并可同时测定离体心脏的机械功能.利用饱和转移技术还能对完整心脏中肌酸激酶和腺苷酸激酶反应的速率加一测定.本文综述介绍了近年来进行离体灌流心脏^3lP NMR谱测定的实验方法以及这一技术所提供的各种信息.     

Alpha spectroscopy in CR-39 SSNTDs using energy simulation and matrix of energy equations for open field studies

Encouraged with the success of the matrix of energy equations in resolving alpha spectra for narrow energy band [O.A. Bondarenko, P.L. Salmon, D.L. Henshaw, A.P. Fews, Radiat. Meas. 26 (1996) 59; O.A. Bondarenko, P.L. Salmon, D.L. Henshaw, A.P. Fews, A.N. Ross, Nucl. Instrum. Methods A 369 (1996) 582] and wide energy band [E.M. Awad, A.A. Soliman, Y.S. Rammah, Phys. Lett. A 369 (5-6) (2007) 359] as well, the present work extends the applicability of this method to work out for open field studies. ²⁴¹Am alpha source was used for irradiating CR-39 samples in air at normal temperature and pressure and at three different distances to obtain three different energies. Alpha particles were sorted to ten different bins according to their dip angle and the energy inside each bin was determined using alpha particle range-energy relation. Then, the energy matrix inside each bin was constructed using some selected calibration tracks. This matrix was composed of two track axes, the track minor axis (m) and diameter of etched out track end (d) of some selected elliptical tracks. The energy E in (m,d) coordinates was given by . The adjusting parameters aij were obtained by solving an over-determined system of energy equations using the SVD method. The three energies in each bin were well resolved.     

Modeling of 31P-NMR spectra of magnetically oriented phospholipid liposomes: A new analytical solution

³¹P-NMR spectroscopy is widely used for studies of phospholipid liposomes, a commonly used model of a biological membrane. For the correct analysis of ³¹P-NMR spectra of the liposomes it is necessary to take into account that they are deformed by the magnetic field of the spectrometer. The liposomes become ellipsoidal and this affects the lineshape of the spectrum. In the present communication we suggest a new analytical formula for modeling of ³¹P-NMR spectra of the prolate phospholipid liposomes. The formula assumes a Lorentzian broadening function and exactly ellipsoidal shape of the liposomes. Based on the formula a program called P-FIT is designed for the practical analysis of the experimental multicomponent spectra of the prolate liposomes. The versatility of the program developed in a Mathematica environment is demonstrated by simulations of a number of ³¹P-NMR spectra with different complexity.     

Energy distribution and energy fluctuation in Tsallis statistics

The energy distribution and the energy fluctuation in the Tsallis canonical ensemble are studied with the OLM formalism but following a new way. The resulting formula for the energy fluctuation is not the same as that in previous work [L.Y. Liu, J.L. Du, Physica A 387 (2008) 5417]. In discussing the application of an ideal gas, we find that the energy fluctuation can not be negligible in the thermodynamic limit, showing the ensemble nonequivalence for this case in Tsallis statistics. We investigate the energy fluctuation with a Tsallis generalized canonical distribution studied by Plastino and Plastino [A.R. Plastino, A. Plastino, Phys. Lett. A 193 (1994) 140] for describing a system in contact with a finite heat bath. For this situation, the two formulae for the energy fluctuation are shown to be equivalent, while the nonextensive parameter q$q$ plays a very important role.     

In vivo (31)P MRS study of skeletal muscle metabolism in patients with postpolio residual paralysis

The muscle metabolism of at-rest patients with varying degrees of postpolio residual paralysis (PPRP) was studied and compared with that of controls using in vivo phosphorus magnetic resonance spectroscopy. The phosphocreatine (PCr)/inorganic phosphate (Pi) and PCr/adenosine triphosphate ratios were lower in patients than in controls. Reduction in PCr/Pi suggests abnormalities in oxidative phosphorylation. A significant increase was observed in the phosphomonoester/PCr ratio in patients, indicating the accumulation of intermediary compounds of the glycolytic pathway. Furthermore, the phosphodiester/PCr ratio was also significantly increased in patients. In general, the observed changes in metabolite ratios were found to be related to the degree of residual paralysis, suggesting that metabolic changes are secondary to chronic neurogenic processes. These metabolic alterations appear to be the possible cause of energy deficit and underlying muscle fatigue in PPRP patients. The present results provide an insight into the metabolic impairment and degree of muscle damage in patients with PPRP.     

Effects of hepatic impairment on the metabolism of fructose and 5-fluorouracil, as studied in fatty liver models using in vivo 31P-MRS and 19F-MRS

The purpose of this study was to observe the effects of hepatic impairment on the metabolism of fructose and 5-fluorouracil (5-FU) in fatty liver models using in vivo 31P-MRS and 19F-MRS and to compare the results. In addition, we compared the results to those of other conventional tests such as laboratory examinations, imaging and pathology. Male SIc:Wistar rats were examined on BEM170/200 (4.7 T, Otsuka Electronics, USA) with 17-mm diameter surface coil. Fatty liver was induced by a choline deficient diet (CD diet) for 2 weeks. 31P-MRS were obtained for 90 min after intravenous (i.v.) injection of 1 g/kg of fructose and 19F-MRS were measured for 100 min after i.v. injection of 100 mg/kg of 5-FU. 1H-MRS and 1H-MRI were also performed. On 31P-MRS, there was no statistical difference in the time course of phosphomonoester (PME), adenosine triphosphate (ATP), and inorganic phosphate (Pi) between CD diet group and control group. On 19F-MRS, we detected high peak of fluoronucleotide (Fnct) and suppressed peak of alpha-fluoro-beta-alanine (FBAL) in CD diet group. We showed the metabolism of fructose and 5-FU by 31P-MRS and 19F-MRS, respectively. There was no difference in fructose metabolism but we observed increased fluoronucleotide and decreased a-fluoro-b-alanine in 5-FU metabolism of fatty liver. We speculate that the effects of hepatic impairment in fatty liver may be more severe on 5-FU metabolism and the increased fluoronucleotide may reflect cell proliferation.     

The impact of energy spectrum width in the energy selective electron low-temperature thermionic heat engine at maximum power

A model of thermionic heat engine with the energy selective electron mechanism is studied. Analytical expressions of the power output and efficiency of this device are derived at low temperature, where the chemical potentials of the reservoirs are assumed to be constant. After discussing the impact of the energy spectrum width of the energy selective electron mechanism, we find two bounds (${\eta }_{\pm }$) of efficiency at maximum power exist naturally. When the energy spectrum width increases gradually from zero and then to the semi-infinite case with the infinite upper limit, the efficiency at maximum power decreases monotonously from the upper bound ${\eta }_{+}$ to the lower bound ${\eta }_{?}$ at a given temperature ratio of the cold and hot reservoirs. The two bound are given by numerical simulation and by an analytical expression respectively. These results may provide some guidance for the application of the practical energy selective electron heat engines.