Smart packaging: sensors for monitoring of food quality and safety

The development of chemical sensors and biosensors over several decades has been investigated resulting in novel and very interesting sensor devices with great promise for many areas of applications including food technology. The incorporation of such sensors into the food packaging technology has resulted what we call smart or intelligent packaging. These are truly integrated and interdisciplinary systems that invoke expertise from the fields of chemistry, biochemistry, physics and electronics as well as food science and technology. Smart packaging utilises chemical sensor or biosensor to monitor the quality & safety of food from the producers to the costumers. This technology can result in a variety of sensor designs that are suitable for monitoring of food quality and safety, such as freshness, pathogens, leakage, carbon dioxide, oxygen, pH, time or temperature. Thus, this technology is needed as on-line quality control and safety in term of consumers, authorities and food producers, and has great potential in the development of new sensing systems integrated in the food packaging, which are beyond the existing conventional technologies, like control of weight, volume, colour and appearance.     

Melt Production and Antimicrobial Efficiency of Low-Density Polyethylene (LDPE)-Silver Nanocomposite Film

Colloidal silver nanoparticles with a size of 5.5 ± 1.1 nm were prepared by chemical reduction using polyethylene glycol (PEG). Silver nanoparticles were incorporated into low-density polyethylene (LDPE) by melt blending and subsequent hot pressing at 140 °C to produce nanocomposite film with an average thickness of 0.7 mm. PEG was added at 5% weight of polymer as a compatibilizer agent in order to prevent agglomeration and provide uniform distribution of nanoparticles in polymer matrix. Antimicrobial activity of silver nanocomposites against Escherichia coli ATCC 13706, Staphylococcus aureus ATCC12600, and Candida albicans ATCC10231 was evaluated by semi-qualitative agar diffusion test and quantitative dynamic shake flask test. Mechanical properties of nanocomposites were not significantly different from silver-free LDPE-containing PEG films (p > 0.05), and silver nanoparticles did not form chemical bonding with the polymer. LDPE-silver nanocomposite samples by more than 6.69 ppm silver nanoparticles showed considerable antimicrobial clear zone. LDPE-silver nanocomposite affected growth kinetic parameters of the examined bacteria and is more efficient on S. aureus than E. coli. Polyethylene-silver nanocomposites containing 22.64 ppm silver nanoparticles could reduce 57.8% growth rate and 23.3% maximum bacterial concentration and increase 35.8% lag time of S. aureus. This study shows the potential use of LDPE-silver nanocomposite as antimicrobial active film. Antimicrobial efficiency of silver nanocomposite depends on silver nanoparticles concentration; however, high level of silver nanoparticles may lead to weakening of mechanical properties.     

Portal hypertension changes following selective splenorenal shunt surgery. Evaluation by percutaneous transhepatic portal catheterization, venography, and cinefluorography

A series of ergot alkaloids, together with the DA agonists apomorphine and piribedil, were tested for protective effects against audiogenic seizures in an inbred strain of mice (DBA/2) and for induction of circling behaviour in mice with unilateral destruction of one nigrostriatal DA pathway. The order of potency against audiogenic seizures was apomorphine greater than ergocornine greater than bromocryptine greater than ergometrine greater than LSD greater than methysergide greater than piribedil while that observed in the rotating mouse model was apomorphine greater than ergometrine greater than ergocornine greater than bromocryptine greater than piribedil. LSD caused only weak circling behaviour even when administered in high doses (greater than 1 mg/kg). Methysergide was ineffective. Prior administration of the neuroleptic agent haloperidol blocked the effect of DA agonists and of ergot alkaloids in both animal models. The possible action of ergot alkaloids as DA agonists is discussed.     

Lymphocyte transformation in vitro in dermatophytosis

Peripheral blood lymphocytes from 59 patients with dermatophytosis and from nine young healthy women were studied by the lymphocyte transformation test (LT) using mitogens and bacterial as well as fungal antigens. The latter included Candida albicans (CA) and four dermatophyte species, viz. Trichophyton rubrum (TR), Trichophyton mentagrophytes (TM), Epidermophyton floccosum (EF) and Microsporum canis (MF). Most of the patients showed normal transformation in response to mitogens and non-dermatophyte antigens, indicating that they have no functional T-cell deficiency. Dermatophyte antigens act as stimulators in LT. In general, patient lymphocytes responded more strongly to these antigens than lymphocytes from controls. In most patients suffering from TM infections, response to the TM antigen was significantly stronger (p less than 0.05) than that in the other patients, indicating that this antigen preparation shows species specificity. In patients with Trichophyton (TR + TM) infections, response to the corresponding antigens was significantly stronger than that in the other patients, which suggests the existence of genus specificity. Any differences between patients suffering from chronic TR infections and those with acute TR infections were not observed, a finding which is in contrast to those obtained in other studies. However, a few patients with chronic TM infections responded weakly to mitogens and non-dermatophyte antigens. LT in four patients with id-reaction to TM infection was not found to differ from that in the remaining TM patients.     

Severe mental retardation among children in the county of Arhus, Denmark. A community study on prevalence and provision of service

(1) We have used both subjective and evoked potential tests to study cases of multiple sclerosis with no history of retrobulbar neuritis (spinal patients) and compared them with patients with multiple sclerosis who had experienced an attack of retrobulbar neuritis (RBN). We measured the delay of steady-state evoked potentials (EPs) elicited by flicker in the medium-frequency (13-25 c/s) range, by flicker in the high-frequency (30-60 c/s) range, and by pattern-reversal. We also measured the delay in seeing (perceiving) both an increase of light intensity and a decrease of light intensity. (2) The difference between perceptual delays for the left and right eyes (D s) was abnormal when retrobulbar neuritis affected only one eye (22/22 patients) even when acuity and discs were normal. It might be supposed that this perceptual test would be ineffective when both eyes were affected by retrobulbar neuritis. However, the value of D was abnormal in cases of bilateral retrobulbar neuritis (5/5 patients). Probably the principal reason is that demyelination was patchy in the patients studied. For this same reason the difference between perceptual delays for two sites in the visual field (T s) may also be abnormal. In principle the perceptual delay test can be effective even when both eyes are similarly delayed: abnormal values of T were recorded in 5 spinal patients for whom D was normal. (3) Perceptual delays were measured for an extended group of 19 patients suffering from spinal multiple sclerosis. Taking both D and T into account, the perceptual delay test alone picked out 12/19 spinal patients. The perceptual delay test has the advantage over EP tests that it can detect islands of demyelination as small as 3 degrees diameter, and the apparatus is cheap and straightforward to use. (4) Thirteen patients with spinal multiple sclerosis, including 6 with no ocular signs or symptoms, were examined with a battery of two evoked potential and one perceptual test. Ten patients had clearly abnormal visual delays. Results for the remaining 3 were equivocal. Delay tests can reveal visual damage in most patients who have not experienced an attack of RBN as well as in practically all patients who have experienced an attack. (5) Correlations between the results of the various tests were different in spinal patients and in multiple sclerosis patients who had experienced an attack of retrobulbar neuritis. Flicker EPs, pattern EPs and visual perception were all delayed in every RBN patient, whereas for spinal patients different tests could pick up different patients. Flicker EPs picked up 5/13 spinal patients, pattern EPs 6/13, perceptual delay (D) picked up 4/13 and perceptual delay T picked up 7/13. (6) Delay tests divided spinal multiple sclerosis patients into two fairly distinct groups. In one group pattern EPs and perception were delayed; in the other group flicker EPs were delayed. This grouping corresponded to a clinical distinction between long-standing patients with visual signs and recent patients without visual signs...     

Pigmented lesions in newborn infants

1058 newborn infants were examined. Forty-one (3-9%) had clinically discernible pigmented lesions compatible with melanocytic naevi. Biopsy was performed on thirty-four of the forty-one and of these; eleven, representing 1-01% of the infants, proved to be melanocytic naevi. No giant (garment) naevi were seen in this series. Two of the eleven naevi pathologically examined showed histological changes similar to those that have been reported in some giant naevi, but the remaining nine were not only different from criteria usually assigned to giant naevi, but they also differed from the usual adult naevi, in that most were predominantly junctional. None of the melanocytic naevi in this series showed any suggestion of malignant change. In newborn infants it is often impossible clinically to distinguish naevi from other types of pigmented lesions, as only eleven out of the thirty-four pigmented lesions were melanocytic naevi. Seven of the eleven melanocytic naevi were under 1-5 cm in diameter. No pigmented lesions were found on the palms, soles or genitalia.