Picosecond spectrochronography

The general problem of extracting complete (amplitude and phase) information out of an optical signal is discussed. We have shown that the best one can do to determine all essential features of light pulses is to apply simultaneous temporal and spectral analysis to take spectrochronograms with the appropriate shape of the resolution cell on theomegat-plane. We use the term "spectrochronogram" instead of the much broader term "time-resolved spectrum" for a specific measurement result where the resolutionsDeltaomegaandDeltatused are transform correlated. A novel subtractive mount of monochromators has been proposed to overcome the obstacles to experimental realization of uncertainty-principle-limited setups for high spectral resolution picosecond spectrochronography. For the examples of perylene and anthracene molecules, experimental spectrochronograms revealing temporal behavior of hot luminescence lines and, correspondingly, picosecond kinetics of intramolecular vibrational relaxation have been presented. Some further applications of picosecond spectrochronography have been discussed.     

Effect of pre‐germination time of brown rice on serum cholesterol levels of hypercholesterolaemic rats

BACKGROUND: Brown rice is unpolished rice with immeasurable benefits for human health. Brown rice (BR) and pre‐germinated brown rice (PGBR) are known to contain various functional compounds such as γ‐oryzanol, dietary fibre and γ‐aminobutyric acid (GABA). In the present study, the experimental diets containing BR and PGBR (24, 48 h pre‐germination) were used to investigate the influence of pre‐germination time of brown rice on blood cholesterol in Sprague–Dawley male rats. RESULTS: Hypercholesterolaemia and elevation of LDL‐cholesterol were successfully ameliorated by the experimental diets containing BR and PGBR (24 and 48 h pre‐germination). As compared to the control sample, the pre‐germination time had a significant (P < 0.05) effect on blood cholesterol of Sprague–Dawley male rats. It was also found that the significantly (P < 0.05) better effect on lipid profile of hypercholesterolaemic rats was observed by prolonging the pre‐germination time. As compared to non‐germinated brown rice, the germinated brown rice showed the higher cardio‐protective effect on hypercholesterolaemic Sprague–Dawley male rats. CONCLUSION: The present study suggests that the changes of blood cholesterol can be mainly modulated by using the PGBR rather than BR. The prolonging of pre‐germination time led to an increase in the bioactive components, thereby providing a more efficient functional diet affecting the high blood cholesterol. This study suggests that PGBR can be used instead of BR and polished rice in the human diet. Copyright © 2009 Society of Chemical Industry     

Programmable SiGe BiCMOS low-pass filter for a multicarrier WCDMA base-station receiver

SiGe BiCMOS low-pass filter for a multicarrier WCDMA base-station receiver is described in this paper. The 4th-order Chebyshev filter with a 0.1-dB passband ripple is designed to drive a high-resolution A/D converter. The −3-dB frequency of the implemented filter can be programmed to four different bandwidths: 2.5, 5, 7.5, and 10 MHz depending on the number of received WCDMA channels. The filter achieves +9.7-dBV in-band IIP3, +20-dBV out-of-band IIP3, and 8.5-nV/√Hz input-referred noise density with 10-MHz bandwidth. The circuit uses a 2.5 V supply and has been fabricated in a 0.25-μm SiGe BiCMOS process.     

Aroma precursors and methylpyrazines in underfermented cocoa beans induced by endogenous carboxypeptidase

Cocoa-specific aroma precursors and methylpyrazines in underfermented cocoa beans obtained from fermentation induced by indigenous carboxypeptidase have been investigated. Fermentation conditions and cocoa bean components were analyzed during 0 to 3 d of fermentation. Underfermented cocoa beans were characterized as having hydrophilic peptides and free hydrophobic amino acids much higher than unfermented ones. These 2 key components of cocoa aroma precursors may be produced from the breakdown of proteins and polypeptides by endogenous carboxypeptidase during the fermentation process. The enzyme was activated during fermentation. Polypeptides of 47, 31, and 19 kDa were observed in the samples throughout the 3-d fermentation period; however, only the first 2 polypeptides were remarkably reduced during fermentation. Since the 1st day of fermentation, underfermented cocoa beans contained methylpyrazines, a dominant group of cocoa-specific aroma. This might be due to microbial activities during fermentation, observed through a decrease of pH value and an increase of temperature of cocoa beans. The concentration of tetramethylpyrazines was significantly increased during the 3 d of fermentation. This may increase the cocoa-specific flavor to the beans.     

Vital parameters for high gamma-aminobutyric acid (GABA) production by an industrial soy sauce koji Aspergillus oryzae NSK in submerged-liquid fermentation

Food Science and Biotechnology - In submerged-liquid fermentation, seven key parameters were assessed using one-factor-at-a-time to obtain the highest GABA yield using an industrial soy sauce koji...     

Formation of 4-hydroxynonenal, a toxic aldehyde, in soybean oil at frying temperature

The formation of 4-hydroxy-2-trans-nonenal (HNE), a mutagenic and cytotoxic product of the peroxidation of linoleic acid, was monitored in soybean oil that was heated at 185°C for 2, 4, 6, 8, and 10 h. Unheated soybean oil contained no HNE and a relatively low concentration of polar lipophilic secondary oxidation products (aldehydes and related carbonyl compounds), measured as 2,4-dinitrophenylhydrazine derivatives by HPLC. An increase in the concentration of both HNE and total lipophilic polar oxidation products was observed with increased exposure to frying temperature. A considerable concentration of HNE had already formed at 2 h and the concentration continued to increase at 4 and 6 h of heating. After 6 h the concentration of HNE decreased, possibly due to degradation of the aldehyde with further exposure to high temperature. The loss of endogenous tocopherols was also monitored in the heated oil, and the tocopherol concentration decreased as the secondary lipid oxidation products increased.     

The effect of intermittent and continuous heating of soybean oil at frying temperature on the formation of 4-hydroxy-2-trans-nonenal and other α-, β-unsaturated hydroxyaldehydes

4-Hydroxy-2-trans-nonenal (HNE) is a cytotoxic secondary lipid peroxidation product of linoleic acid. Previous investigations in this laboratory showed that HNE is formed in thermally oxidized soybean oil, which is high in linoleic acid. Continuous exposure of the oil to frying temperature (185°C) for up to 6 h graduallyincreased the formation of HNE and other polar lipophilic aldehydes. Additional investigations in this laboratory showed that HNE is absorbed into food fried in thermally oxidized oil in the same concentration as was found in the oil. In the present experiment, the effect of intermittent heating on the formation of HNE in soybean oil was compared with continuous heating. Soybean oil samples were heated either for 1 h each day for five sequential days or for 5 h continuously at 185±5°C. The thermally oxidized soybean oil samples were analyzed by HPLC for the presence of HNE and three other polar lipophilic α-,β-unsaturated hydroxyaldehydes: 4-hydroxy-2-trans-hexanal, 4-hydroxy-2-trans-octenal, and 4-hydroxy-2-trans-decenal. Under intermittent and continuous heating over a total of 5 h, the concentration of these compounds increased similarly. These results indicate that the formation of HNE and other hydroxyaldehydes at frying temperature is a cumulative result of oxidation of PUFA over time.     

Effects of Temperature and Heating Time on the Formation of Four Toxic α,β‐Unsaturated‐4‐Hydroxyaldehydes in Vegetable Oils

The formation of four α,β‐unsaturated hydroxyaldehydes, 4‐hydroxy‐2‐trans‐hexenal (HHE), 4‐hydroxy‐2‐trans‐octenal (HOE), 4‐hydroxy‐2‐trans‐nonenal (HNE), and 4‐hydroxy‐2‐trans‐decenal (HDE), was detected in commercial corn, soybean, peanut, and canola oils heated for 1, 3, and 5 hours at 145, 165, and 185 °C. These four toxic aldehydes were investigated using high‐performance liquid chromatography (HPLC). These oils were selected based upon different degrees of unsaturations, especially their linoleic and linolenic acid concentrations. To select the appropriate conditions of temperatures and heating times, preliminary experiments were conducted using the thiobarbituric acid assay, which detects the formation of secondary‐oxidation products such as aldehydes and related carbonyl compounds. After various heat treatments, the formation of HHE, HOE, HNE, and HDE was detected as 2,4‐dinitrophenyl hydrazine derivatives using HPLC. In general, HHE, HOE, HNE, and HDE formation increased in all four oils with higher temperatures, longer heating times, and higher concentrations of linoleic and linolenic acids in the oils. The formation of HNE in the oils was mostly much higher than the other three 4‐hydroxyaldehyde isomers under the same conditions.     

Modulation of Lipid Metabolism by Centella Asiatica in Oxidative Stress Rats

ABSTRACT:  A study was carried out to investigate the effects of Centella asiatica leaf on lipid metabolism of oxidative stress rats. The rats were fed 0.1% hydrogen peroxide (H₂O₂) with either 0.3% (w/w) C. asiatica extract, 5% C. asiatica powder (w/w), or 0.3% (w/w) α-tocopherol for 25 wk. Results of the study showed that C. asiatica powder significantly ( P < 0.05) lowered serum low-density lipoprotein compared to that of control rats (rats fed H₂O₂ only). At the end of the study C. asiatica -fed rats were also found to have significantly ( P < 0.05) higher high-density lipoprotein and lower triglyceride level compared to rats fed only normal diet. However, cholesterol level of rats fed both C. asiatica extract and powder was found to be significantly ( P < 0.05) higher compared to that of control rats. It was interesting to note that consumption of C. asiatica significantly decreased body and liver weights of the rats. Histological examinations revealed no obvious changes in all rats studied. Quantitative analysis of C. asiatica leaf revealed high concentration of total phenolic compounds, in particular, catechin, quercetin, and rutin.