Drying of Carrots in a Fluidized Bed. II. Design of a Model Based on a Modular Neural Network Approach

The present paper deals with the design of a neural network type model for drying of carrots, which includes the associated transport mechanisms of the process. The model uses the operational variables and the time as input parameters. Two sub-layers of linear and sigmoidal nodes make up the hidden layer, to represent the external and internal resistances to the diffusion of water vapors during the drying process. The single output node weights the contribution of each mechanism of the drying process to predict the exit moisture content of the product. This model was used to predict the drying of carrot particles in a mechanically fluidized bed dryer reported in a previous paper [Reyes, A.; Alvarez, P.; Marquardt, F. Drying of carrots in a fluidized bed: I.- effects of drying conditions and modeling. Drying Technology 2002, 20 (7), 1463-1483.]. Simulated drying curves obtained with this model fits adequately the curves determined experimentally for the most operation conditions, which would indicate that this model is appropriate to be used for rough estimations in the design, the selection of optimal operational conditions, and the scaling up of dryers.     

Morphogenesis of the epithelial cell transporting phenotype: synthesis and distribution of ion channels

Open partial trapeziectomy and interpositional arthroplasty have proven to be effective in ameliorating the symptoms of carpometacarpal joint arthritis of the thumb. Surgical technique of arthroscopic partial resection of the trapezium and interpositional arthroplasty is described. Thirty-three interpositional arthroplasties were carried out arthroscopically. Autogenous tendon graft. Gortex (WL Gore & Associates, Inc. Flagstaff, AZ) and fascia lata allograft were used as interpositional material; 87.8% of patients got relief from pain. Average postoperative pinch strength was 11 lbs. No ligament reconstruction was required because the capsule was left intact. The procedures were done on an outpatient basis and all patients were discharged the same day. There were no complications associated with radial sensory nerve.     

Room temperature migration of ion beam injected point defects in crystalline silicon

We have investigated the room temperature diffusion and trapping phenomena of ion beam generated point defects in crystalline Si by monitoring their interaction with dopants, native contaminants such as C and O, and other defects. Spreading resistance measurements show that a small fraction ( 10⁻⁷–10⁻⁶) of the defects generated at the surface by a 40 keV Si implant is injected into the bulk. These defects undergo trap-limited diffusion and produce dopant deactivation and/or partial annihilation of preexisting deep (several micron) defect markers, produced by MeV He implants. It is found that in highly pure, epitaxial Si layers, these effects extend to several microns from the surface, demonstrating a long range migration of point defects at room temperature. A detailed analysis of the experimental evidences allows us to identify the Si self-interstitials injected into the bulk as the major responsible of both dopant deactivation and partial annealing of vacancy-type defects (divacancies, phosphorus-vacancy and oxygen-vacancy) generated by the implants. Finally, a lower limit of 6 × 10⁻¹¹ cm²/s is obtained for the room temperature diffusivity of Si self-interstitials.     

A multifractal comminution approach for drilling scaling laws

The drilling comminution is theoretically and experimentally analyzed by a multifractal approach. A generalization of the three classical comminution laws [Rittinger, P.R., 1867. Lehrbuch der Aufbereitungskunde. Berlin; Kick, F., 1885. Das Gesetz der Proportionalen Widerstände. Leipzig; Bond, F.C., Min. Eng. 193 (1952) 484] has been performed to evaluate the energy dissipation in the process and to compute the mass distribution of the particles. A transitional fractal exponent of the fragment size distribution is experimentally demonstrated to exist. As a consequence, a multifractal scaling law for the partial mass of fragments and its physical interpretation is consistently proposed.In addition, we show, both theoretically and experimentally, that the drilling strength is strongly size-dependent and cannot be considered a material constant, as classically supposed. Consequently, a multifractal scaling law for the drilling strength is also proposed.     

Dephosphorization and desulfurization of molten Fe-Cr-C alloys

Thermodynamic calculation of phosphorus-chromium and sulfur-chromium relationships in molten Fe-Cr-P-C and Fe-Cr-S-C alloys at 0 to 18 wt. % Cr and 0 to 6 wt. % C. Experiments to prove the potentiality of dephosphorization and desulfurization of Fe-Cr alloys at 18 wt. % Cr and elevated carbon contents using highly basic FeO_n-CaO-CaF₂-BaF₂ slag.     

Chronic stress effects on the apoptotic index of the adrenal cortex of pregnant rats.

Chronic stress by immobilization during gestation can alter several mechanisms that maintain homeostasis in adrenal gland. The aim of this work was to quantify the apoptotic index of adrenal cortex during mid-pregnancy and to prove cytological characteristics by electron microscopy. The apoptotic index did not present significant differences between the adrenal cortex areas of control and experimental rats in any of the three ages studied. The day of gestation influenced significantly on the apoptotic index in both groups. This index increased as gestation progressed. It may be concluded that chronic stress by immobilization might induce the increase of apoptotic index in adrenal cortex as gestation progresses which might be related variations of plasmatic corticosterone and prolactin, and to the decrease of specific growth factors. On the other hand, it might be concluded that each zone of adrenal cortex behaves independently in regards to apoptosis and cellular proliferation via paracrine and/or autocrine regulatory mechanisms without being affected by other zones.     

Differential stimulation of interleukin-12 (IL-12) and IL-10 by live and killed Helicobacter pylori in vitro and association of IL-12 production with gamma interferon-producing T cells in the human gastric mucosa

The objective of these experiments was to examine the ability of Helicobacter pylori to stimulate interleukin-10 (IL-10) or IL-12 and select for either Th1 or Th2 cells. Gastric biopsy specimens were collected from patients who were categorized with respect to the presence of H. pylori and gastric disease as well as their age, gender, medications, and other factors. As Th1 and Th2 cells are selected by IL-12 and IL-10, respectively, biopsy specimens were screened for mRNA and protein for these cytokines. Although mRNA for IL-12 and IL-10 was detected in biopsy specimens obtained from both infected and uninfected patients, IL-12 protein predominated. Levels of IL-10 and IL-12 in gastric tissue did not change in response to infection. Moreover, gamma interferon (IFN-gamma)-producing T cells were found in both the infected and the uninfected gastric mucosa. Stimulation of peripheral blood leukocytes from either infected or uninfected donors with various concentrations of live or killed H. pylori induced immunoreactive IL-12 and IL-10. After stimulation with live H. pylori, IL-12 levels increased more than 30-fold, whereas IL-10 levels increased only 2- to 5-fold, compared to cells stimulated with medium alone. Interestingly, killed H. pylori induced significantly more IL-10 (P < 0.05) than live H. pylori, while recombinant urease only induced IL-10. These results demonstrate that live H. pylori selectively stimulates the induction of IL-12 and Th1 cells that produce IFN-gamma, whereas preparations used in oral vaccines induce more IL-10 and may favor Th2 cell responses.     

Programmable time-multiplexed switched-capacitor variable equalizerfor arbitrary frequency response realizations

A time-multiplexed digitally-programmable switched-capacitor (SC) variable equalizer which allows the realization of arbitrary frequency responses is presented. The circuit performs the same operation as a cascade of N second-order programmable equalizers, where N is also the multiplexing order. Except the storing capacitors, the rest of the circuitry is shared for all individual equalizer functions (channels), resulting in silicon area savings higher than 60% with respect to a direct circuit implementation for N=4. The impact on circuit performance of crosstalk effects is discussed. Experimental results of a 3-V timesharing SC equalizer architecture fabricated in a CMOS 1.2 μm technology are given for different values of the multiplexing order. The circuit has been designed to be incorporated in a programmable hearing aid device     

Management of posttransplant lymphoproliferative disease in pediatric liver transplant recipients receiving primary tacrolimus (FK506) therapy

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) after pediatric liver transplantation has been associated with high mortality rates. METHODS: The present study examined 282 consecutive pediatric liver transplant recipients from October 1989 to June 1996 who received primary tacrolimus immunosuppression. The aim was to determine the incidence of PTLD, management strategies, and patient outcome. RESULTS: The incidence of PTLD was 13% (361282) with a mean age of 5.5+/-0.7 years (range 0.6 to 15) at diagnosis. The average time from transplantation to PTLD was 10.1+/-2.1 months. Initial treatment of PTLD consisted of reduction (3 patients) or discontinuation (33 patients) of tacrolimus and initiation of antiviral therapy (intravenous ganciclovir, 14 patients; intravenous acyclovir, 22 patients; or both, 5 patients). Alpha-interferon was used in four patients (two successfully). One patient also received gamma-interferon, chemotherapy, and radiation for a central nervous system lesion. Chemotherapy was also used in one patient with Burkitt's, whereas one patient with a pulmonary lesion received additional radiation therapy. Three patients received supportive surgery for gastrointestinal involvement, and one patient had a splenectomy for hemolysis. Overall mortality was 22% (8/36) with 5 (14%) PTLD-related deaths (disseminated disease, 4 patients; bowel perforation, 1 patient). Of 31 survivors, 23 had acute rejection at a median time of 24 days after PTLD, with 2 patients developing chronic rejection. One patient required retransplantation. Present immunosuppression consists of tacrolimus monotherapy in 14 patients, tacrolimus/prednisone in 8 patients, and none in 6 patients. CONCLUSION: In summary, PTLD can be successfully treated with reduction of immunosuppression and administration of antiviral agents in most patients. The management of rejection after PTLD requires reassessment of disease status and judicious reintroduction of immunosuppression therapy.     

Pectinlyase immobilization on polyamides for application in the food processing industry

The study concerns the immobilization of a pectinlyase (PL, EC 4.2.2.3) purified by means of a commercial enzyme for its possible applications in fruit juice and beverage processing. Results previously obtained were improved by employing polyamides, i.e. nylon 6 and nylon 11, activated by easy to perform and inexpensive methods such as direct activation with glutaraldehyde and alkylation with dimethylsulphate followed by treatment with amines and glutaraldehyde. The nylon 6 activated with glutaraldehyde gave an activity of the immobilized PL of about 200 U g^?1 (at optimum pH) and a half-life of about 190 h (at pH 3·3 and 25°C).