Numerical simulation and study on heat and mass transfer in a hybrid ultrasound/convective dryer

Susceptibility of airborne ultrasonic power to augment heat and mass transfer during hot air dehydration of peppermint leaves was investigated in the present study. To predict the moisture removal curves, a unique non-equilibrium mathematical model was developed. For the samples dried at temperatures of 40‒70 °C and the power intensities of 0‒104 kW m-3, the diffusion of moisture inside the leaves and coefficients for of mass and heat transfer varied from 0.601 × 10-4 to 5.937 × 10-4 s-1, 4.693 × 10-4 to 7.975 × 10-4 m s-1 and 49.2 to 78.1 W m-2 K-1, respectively. In general, at the process temperatures up to 60 °C, all the studied transfer parameters were augmented in the presence of ultrasonic power.

Optimum drying conditions for ginger (Zingiber officinale Roscoe) based on time, energy consumption and physicochemical quality

The effect of ultrasonic pre-treatment on moisture removal characteristics of ginger in a convective dryer was investigated. The slabs were dried by practicing sonication durations of 0, 15 and 30 min at different levels of the air temperature and velocity. Following increasing the sonication duration and air temperature, required time and energy to dehydrate the samples were decreased. The pre-treatment played important role in improving rehydration capability and surface color retention in the dried gingers. Content of the main volatile component (α-Zingiberene) was not influenced by the sonication. Mean values for the phenolic contents and antioxidant activity at sonication duration of 0, 15 and 30 min were determined to be 18.93, 18.15 and 17.49 GAE/g dry matter and 83.57, 78.33 and 74.58 %, respectively. The desired values for the temperature, velocity and sonication duration were revealed to be about 66 °C, 3 m/s and 20 min, respectively.

INFRARED DEHYDRATION OF BLANCHED QUINCE SLICES: STUDY ON PROCESS AND MASS TRANSFER CHARACTERISTICS

In the present work, moisture removal characteristics of quince slices in a convective tray dryer were studied. The blanched slices (with thicknesses of 3, 5 and 7 mm) were dried at drying temperatures of 50, 60 and 70 °C and air flow rates of 1, 1.5 and 2 m/s. The analytical model proposed by Dincer and Dost was used to determine the mass transfer parameters. The obtained Biot numbers (0.108‒0.293) revealed that both the internal and external resistance control the moisture diffusion within the samples. The moisture diffusivity and convective mass transfer coefficient were found to be in the ranges of 1.578×10-7‒7.331×10-7 m2/s and 2.040×10-5‒3.507×10-5 m/s, respectively. The activation energies for moisture diffusion and surface mass evaporation were determined to be in the ranges of 17.607 to 48.019 kJ/mol and 5.270 to 27.430 kJ/mol, respectively.

Levodopa medication improves incidental sequence learning in Parkinson's disease

Empirical evidence suggests that levodopa medication used to treat the motor symptoms of Parkinson's disease (PD) may either improve, impair or not affect specific cognitive processes. This evidence led to the 'dopamine overdose' hypothesis that levodopa medication impairs performance on cognitive tasks if they recruit fronto-striatal circuits which are not yet dopamine-depleted in early PD and as a result the medication leads to an excess of dopamine. This hypothesis has been supported for various learning tasks including conditional associative learning, reversal learning, classification learning and intentional deterministic sequence learning, on all of which PD patients demonstrated significantly worse performance when tested on relative to off dopamine medication. Incidental sequence learning is impaired in PD, but how such learning is affected by dopaminergic therapy remains undetermined. The aim of the current study was to investigate the effect of dopaminergic medication on incidental sequence learning in PD. We used a probabilistic serial reaction time task (SRTT), a sequence learning paradigm considered to make the sequence less apparent and more likely to be learned incidentally rather than intentionally. We compared learning by the same group of PD patients (n=15) on two separate occasions following oral administration of levodopa medication (on state) and after overnight withdrawal of medication (off state). Our results demonstrate for the first time that levodopa medication enhances incidental learning of a probabilistic sequence on the serial reaction time task in PD. However, neither group significantly differed from performance of a control group without a neurological disease, which indicates the importance of within group comparisons for identifying deficits. Levodopa medication enhanced incidental learning by patients with PD on a probabilistic sequence learning paradigm even though the patients were not aware of the existence of the sequence or their acquired knowledge. The results suggest a role in acquiring incidental motor sequence learning for dorsal striatal areas strongly affected by dopamine depletion in early PD.

Prognostic significance of recurrent chromosomal aberrations detected by comparative genomic hybridization in sporadic colorectal cancer

Colorectal carcinomas are characterized by frequent recurrent gains and losses of chromosomal material, especially gains of chromosome arms 20q and 13q, and losses of chromosome arms 18q and 4q. These may be important in the development and progression of colorectal carcinomas. Chromosomal aberrations detected by comparative genomic hybridization in 67 sporadic colorectal carcinomas were examined for their possible associations with patient survival. Dukes' stage, tumor DNA ploidy status, and TP53 genotype/phenotype were also examined for the same. Patients with losses of chromosomal arms 1p, 4q, 8p, 14q, or 18q or gain of chromosomal arm 20q had significantly shorter survival times than those without these aberrations (univariate relative risk 3.45, 2.71, 3.32, 3.26, 3.32, 3.91, respectively), as did patients with more than six chromosomal aberrations per tumor than those with fewer than six aberrations (univariate relative risk 3.26, P = 0.013). DNA aneuploidy and Dukes' stage C + D resulted in poor patient survival (univariate relative risk 3.58, 3.39, respectively). Dukes' stage C + D, 1p loss and 8p loss emerged as the only independent prognostic parameters (relative risk 3.22, 2.53, 2.45, respectively) when entered into multivariate survival analysis together with other significant parameters from univariate survival analysis. Loss of chromosome arm 1p, 4q, 8p, 14q, or 18q or gain of chromosome arm 20q thus results in shortened survival times in colorectal cancer patients. 1p loss and 8p loss were shown to be independent predictors of poor prognosis.

Dual effects of pertussis toxin on murine neutrophils in vivo. I. Pertussis toxin inhibits extravasation potential of mature neutrophils while simultaneously stimulating granulopoiesis

Pertussis toxin (Ptx) has been employed as an adjuvant by many investigators to augment various types of cell-mediated and humoral immune responses. Recent work from our laboratory indicates that the exacerbation of delayed-type hypersensitivity (DTH) and contact hypersensitivity (CH) responses observed in Ptx-treated mice may be mediated by an absolute increase in the number of circulating neutrophils capable of migrating into tissue sites of antigen challenge. The purpose of the present study was to analyze the effects of Ptx on neutrophils and neutrophil function in vivo. Evidence is presented here suggesting that Ptx has both direct and indirect effects on neutrophils following its in vivo administration to normal mice. Mature neutrophils that are directly exposed to the actions of Ptx in vivo exhibit a marked reduction in their ability to extravasate into tissue sites of inflammation. These findings are consistent with those that have been reported following the exposure of isolated neutrophils to the effects of Ptx in vitro (i.e., that Ptx has an inhibitory effect on many of the functional capabilities of isolated neutrophils). Moreover, we have also determined that Ptx can affect the kinetics of neutrophil production indirectly through its ability to stimulate granulopoiesis. Ptx-exposed mice develop a protracted peripheral blood neutrophilia following toxin administration. Although the mechanism(s) involved in stimulating increased neutrophil production is presently unclear, both dexamethasone and indomethacin (cyclooxygenase pathway inhibitors) are able to function synergistically with Ptx to produce a markedly enhanced neutrophilia in exposed mice. We propose that the capacity of Ptx to augment CH and DTH responses and act as a potent adjuvant may relate, in part, to its ability to alter the rate of neutrophil production in vivo.