Salt content dependent dielectric properties of pistachios relevant to radio-frequency pasteurization.

This study was conducted to investigate the effect of salt content during radio-frequency (RF) heating on rate of temperature increase, dielectric properties (DPs), and reduction of pathogens in pistachios. Also, the effect of RF heating on pistachio quality of varying salt content was determined. Pistachios of different salt content (0, 100, and 330 mg sodium/serving) were inoculated with Salmonella enterica and treated in a 27.12-MHz RF heater. The RF heating rate increased when salt content was in the range of 0-100 mg sodium/serving, but there were no significant (P > 0.05) differences in the rate of temperature rise after salt content reached to 100 mg sodium/serving. Both dielectric constant and dielectric loss factor of pistachios increased with rising salt content. Along with increased salt content, RF treatment time required to reduce this pathogen by 4 log CFU/g decreased first and then remained the same above an upper limit of salt content corresponding to the peak heating rate. RF treatment did not significantly (P > 0.05) cause changes in the color and level of lipid oxidation of pistachios. The results of the current study imply that RF heating may be a potential intervention for inactivating foodborne pathogens in pistachios and that the effect of pasteurization is influenced by dielectric loss factor relative to salt content.

OSL PROPERTIES IN VARIOUS FORMS OF KCl AND NaCl SAMPLES AFTER EXPOSURE TO IONIZING RADIATION.

The aim of this work was to investigate the optically-stimulated luminescence (OSL) properties of potassium chloride (KCl) and its potential use in radiation dosimetry. The optimal condition for OSL readout with blue light stimulation were designated using a commercially available Risø TL/OSL reader. KCl was studied in three sample forms: crystals, powder and pellets. The following OSL characteristics were determined: signal reproducibility, OSL measurement-induced sensitivity changes, temperature dependence of OSL and signal stability over time. The results show a high reproducibility of KCl samples and strong sensitivity changes, which can be corrected for by using a test-dose. The long-term OSL studies confirmed the occurrence of both inverse fading and fading phenomena in KCl. In addition, a comparison with corresponding measurements using sodium chloride (NaCl) were carried out. Although it was confirmed that NaCl is more suitable for dosimetry, there might be benefits of combining NaCl with KCl for more accurate absorbed dose determinations.

Bactericidal effects of deep ultraviolet light-emitting diode for solutions during intravenous infusion.

Background: Ultraviolet irradiation is effectively used as a disinfection method for inactivating microorganisms. Methods: We investigated the bactericidal effects by irradiation with a deep-ultraviolet light-emitting diode (DUV-LED) on the causative microorganisms of catheter related blood stream infection contaminating the solution for intravenous infusion. For irradiation, prototype modules for water disinfection with a DUV-LED were used. Experiments were conducted on five kinds of microorganisms. We examined the dependence of bactericidal action on eleven solutions. Administration sets were carried out three types. Results: When the administration set JY-PB343L containing the infusion tube made of polybutadiene was used, the bactericidal action of the DUV-LED against all tested microorganisms in the physiological saline solutions was considered to be effective. We confirmed that the number of viable bacteria decreased in 5% glucose solution and electrolyte infusions with DUV-LED irradiation. Conclusions: These results indicate that the DUV-LED irradiation has bactericidal effects in glucose infusion and electrolyte infusions by irradiating via a plasticizer-free polybutadiene administration set. We consider DUV-LED irradiation to be clinically applicable.

Influence of extrinsic operational parameters on salt diffusion during ultrasound assisted meat curing.

The present study investigated the effect of geometric parameters of the ultrasound instrument during meat salting in order to enhance salt diffusion and salt distribution in pork meat on a lab scale. The effects of probe size (∅2.5 and 1.3cm) and of different distances between the transducer and the meat sample (0.3, 0.5, and 0.8cm) on NaCl diffusion were investigated. Changes in the moisture content and NaCl gain were used to evaluate salt distribution and diffusion in the samples, parallel and perpendicular to ultrasound propagation direction. Results showed that 0.3cm was the most efficient distance between the probe and the sample to ensure a higher salt diffusion rate. A distance of 0.5cm was however considered as a trade-off distance to ensure salt diffusion and maintenance of meat quality parameters. The enhancement of salt diffusion by ultrasound was observed to decrease with increased horizontal distance from the probe. This study is of valuable importance for meat processing industries willing to apply new technologies on a larger scale and with defined operational standards. The data suggest that the geometric parameters of ultrasound systems can have strong influence on the efficiency of ultrasonic enhancement of NaCl uptake in meat and can be a crucial element in determining salt uptake during meat processing.

Stability of Alprostadil in 0.9% Sodium Chloride Stored in Polyvinyl Chloride Containers.

The stability of alprostadil diluted in 0.9% sodium chloride stored in polyvinyl chloride (VIAFLEX) containers at refrigerated temperature, protected from light, is reported. Five solutions of alprostadil 11 mcg/mL were prepared in 250 mL 0.9% sodium chloride polyvinyl chloride (PL146) containers. The final concentration of alcohol was 2%. Samples were stored under refrigeration (2°C to 8°C) with protection from light. Two containers were submitted for potency testing and analyzed in duplicate with the stability-indicating high-performance liquid chromatography assay at specific time points over 14 days. Three containers were submitted for pH and visual testing at specific time points over 14 days. Stability was defined as retention of 90% to 110% of initial alprostadil concentration, with maintenance of the original clear, colorless, and visually particulate-free solution. Study results reported retention of 90% to 110% initial alprostadil concentration at all time points through day 10. One sample exceeded 110% potency at day 14. pH values did not change appreciably over the 14 days. There were no color changes or particle formation detected in the solutions over the study period. This study concluded that during refrigerated, light-protected storage in polyvinyl chloride (VIAFLEX) containers, a commercial alcohol-containing alprostadil formulation diluted to 11 mcg/mL with 0.9% sodium chloride 250 mL was stable for 10 days.

Infusion of solutions of pre-irradiated components in rats.

INTRODUCTION: The objective of this study was to conduct a 14-day toxicology assessment for intravenous solutions prepared from irradiated resuscitation fluid components and sterile water. METHODS: Healthy Sprague Dawley rats (7-10/group) were instrumented and randomized to receive one of the following Field IntraVenous Resuscitation (FIVR) or commercial fluids; Normal Saline (NS), Lactated Ringer's, 5% Dextrose in NS. Daily clinical observation, chemistry and hematology on days 1,7,14, and urinalysis on day 14 were evaluated for equivalence using a two sample t-test (p<0.05). A board-certified pathologist evaluated organ histopathology on day 14. RESULTS: Equivalence was established for all observation parameters, lactate, sodium, liver enzymes, creatinine, WBC and differential, and urinalysis values. Lack of equivalence for hemoglobin (p=0.055), pH (p=0.0955), glucose (p=0.0889), Alanine-Aminotransferase (p=0.1938), albumin (p=0.1311), and weight (p=0.0555, p=0.1896), was deemed not clinically relevant due to means within physiologically normal ranges. Common microscopic findings randomly distributed among animals of all groups were endocarditis/myocarditis and pulmonary lesions. DISCUSSION: These findings are consistent with complications due to long-term catheter use and suggest no clinically relevant differences in end-organ toxicity between animals infused with FIVR versus commercial fluids.

Investigation of the antimicrobial activity at safe levels for eukaryotic cells of a low power atmospheric pressure inductively coupled plasma source.

Low power atmospheric pressure inductively coupled thermal plasma sources integrated with a quenching device (cold ICP) for the efficient production of biologically active agents have been recently developed for potential biomedical applications. In the present work, in vitro experiments aimed at assessing the decontamination potential of a cold ICP source were carried out on bacteria typically associated with chronic wounds and designed to represent a realistic wound environment; further in vitro experiments were performed to investigate the effects of plasma-irradiated physiological saline solution on eukaryotic cells viability. A thorough characterization of the plasma source and process, for what concerns ultraviolet (UV) radiation and nitric oxide production as well as the variation of pH and the generation of nitrates and nitrites in the treated liquid media, was carried out to garner fundamental insights that could help the interpretation of biological experiments. Direct plasma treatment of bacterial cells, performed at safe level of UV radiation, induces a relevant decontamination, both on agar plate and in physiological saline solution, after just 2 min of treatment. Furthermore, the indirect treatment of eukaryotic cells, carried out by covering them with physiological saline solution irradiated by plasma, in the same conditions selected for the direct treatment of bacterial cells does not show any noticeable adverse effect to their viability. Some considerations regarding the role of the UV radiation on the decontamination potential of bacterial cells and the viability of the eukaryotic ones will be presented. Moreover, the effects of pH variation, nitrate and nitrite concentrations of the plasma-irradiated physiological saline solution on the decontamination of bacterial suspension and on the viability of eukaryotic cells subjected to the indirect treatment will be discussed. The obtained results will be used to optimize the design of the ICP source for an effective production of reactive species, while keeping effluent temperature and UV radiation at values compatible with biomedical treatments.

Photo-Fenton degradation of phenol, 2,4-dichlorophenoxyacetic acid and 2,4-dichlorophenol mixture in saline solution using a falling-film solar reactor.

In this work, a saline aqueous solution of phenol, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-dichlorophenol (2,4-DCP) was treated by the photo-Fenton process in a falling-film solar reactor. The influence of the parameters such as initial pH (5-7), initial concentration of Fe2+ (1-2.5mM) and rate of H202 addition (1.87-3.74mmol min-1) was investigated. The efficiency of photodegradation was determined from the removal of dissolved organic carbon (DOC), described by the species degradation of phenol, 2,4-D and 2,4-DCP. Response surface methodology was employed to assess the effects of the variables investigated, i.e. [Fe2+], [H202] and pH, in the photo-Fenton process with solar irradiation. The results reveal that the variables' initial concentration of Fe2+ and H202 presents predominant effect on pollutants' degradation in terms of DOC removal, while pH showed no influence. Under the most adequate experimental conditions, about 85% DOC removal was obtained in 180 min by using a reaction system employed here, and total removal of phenol, 2,4- and 2,4-DCP mixture in about 30min.

Enhanced surface photochemistry in chloride-nitrate ion mixtures.

Heterogeneous reactions of sea salt aerosol with various oxides of nitrogen lead to replacement of chloride ion by nitrate ion. Studies of the photochemistry of a model system were carried out using deliquesced mixtures of NaCl and NaNO3 on a Teflon substrate. Varying molar ratios of NaCl to NaNO3 (1 : 9 Cl- : NO3-, 1 : 1 Cl- : NO3-, 3 : 1 Cl- : NO3-, 9 : 1 Cl- : NO3-) and NaNO3 at the same total concentration were irradiated in air at 299 +/- 3 K and at a relative humidity of 75 +/- 8% using broadband UVB light (270-380 nm). Gaseous NO2 production was measured as a function of time using a chemiluminescence NO(y) detector. Surprisingly, an enhanced yield of NO2 was observed as the chloride to nitrate ratio increased. Molecular dynamics (MD) simulations show that as the Cl- : NO3- ratio increases, the nitrate ions are drawn closer to the interface due to the existence of a double layer of interfacial Cl- and subsurface Na+. This leads to a decreased solvent cage effect when the nitrate ion photodissociates to NO2+O*-, increasing the effective quantum yield and hence the production of gaseous NO2. The implications of enhanced NO2 and likely OH production as sea salt aerosols become processed in the atmosphere are discussed.

Sonolytic degradation of acetic acid in aqueous solutions.

In this work, ultrasonic degradation of acetic acid, which is one of the most resistant carboxylic acids to oxidize, was investigated. The effects of parameters such as ultrasonic power, initial concentration, addition of NaCl or several oxides were studied on the degradation of acetic acid. Acetic acid was sonicated indirectly using an ultrasonic bath with 40 kHz. It was observed that degradation degree increased with decreasing power and initial concentration and with increasing NaCl concentration. Initial degradation degree was enhanced with addition of zeolite and SiO(2).

Optical absorption and thermoluminescence in single NaCl:Cu crystals exposed to 60Co and UV light.

Optical absorption (OA) and thermally stimulated luminescence measurements were performed on NaCl:Cu+(0.04 and 0.08%) crystals blocks grown by the Czochralski technique. The NaCl:Cu+ crystals were exposed to gamma rays from a 60Co source (0.954-30 kGy) as well as UV radiation. The radiation-induced defects were mainly F, Cu- and Cu+ centres, with absorption bands located at 464, 256.7 and 236 nm, respectively. The absorption bands were found to be independent of the Cu impurity concentration. As the gamma-dose irradiation increased, the absorption band at 256.7 nm decreased while the band at 236.3 nm increased highly along with the 256.7 nm band. The F-centres produced at high gamma-radiation dose while thermally bleached showed an increase of the Cu+ OA bands with a simultaneous decrease of Cu- absorption band. The bleaching with F-light showed the participation of the F centre generated by gamma radiation on the ion valence changes of the doping impurity as well as on the TL phenomenon. The TL measurements in NaCl:Cu crystals with both impurity concentrations demonstrated that the Cu+ concentration has a strong influence on the intensity and shape of the glow peaks.

Thermoluminescence dosimetric characteristics of beta irradiated salt.

The thermoluminescence (TL) characteristics of sodium chloride (NaCl), known as common salt, used for cooking purposes (iodised salt), have been studied in the present paper considering its usage as an 'accidental dosemeter' in the case of a nuclear fallout. TL characteristics of common salt have been examined under excitation with a beta dose of 20 Gy from a 90Sr beta source. The salt specimens are used in the form of discs. The average salt grain that sticks to the disc is measured to be approximately 1 mg. The TL of the beta irradiated salt is recorded in the conventional TL apparatus. Initially three peaks were observed at 133, 205 and 238 degrees C. All three peaks are well resolved, having maximum intensity at 238 degrees C. The material under investigation, i.e. 'common salt' possesses many good dosimetric properties and therefore this can be considered as an 'accidental dosemeter'.

The behavior of single crystals of NaCl: Ca2+, Mn2+ exposed to gamma rays.

The behavior of single crystals of NaCl: Ca(2+), Mn(2+) exposed to gamma rays was explored for its potential usage as a dosimeter. The study was focused to the effect of dose and dose rate. The crystals were analyzed using thermoluminescence (TL). The productions of irradiation defects in the solid were correlated with the glow curve. F-centers were measured as function of the dose. The bleaching of the F-centers produced a decrease of the peak of the glow curve. The results showed that the response is linear in an interval up to 60 Gy.

Advantage of the Mark-III FEL for biophysical research and biomedical applications.

Although 6.45 micro m is not the strongest absorption band of biological tissues in the mid-infrared, a Mark-III free-electron laser (FEL) tuned to this wavelength can efficiently ablate tissue while minimizing collateral damage. A model has previously been presented that explains this wavelength dependence as a competition between two dynamic processes--explosive vaporization of saline and denaturation of structural proteins. Here it is shown that this model predicts a 'sweet-spot' for each wavelength, i.e. a region of parameter space (incident intensity and pulse width) in which explosive vaporization is preceded by substantial protein denaturation. This sweet-spot is much larger for wavelengths where protein is the dominant chromophore. At other wavelengths, collateral damage may be minimized within the sweet-spot, but the maximum intensities and pulse widths in these regions are insufficient to remove tissue at surgically relevant rates.

The thermal field of radiofrequency probes at chondroplasty settings.

PURPOSE: The purpose of this experimental study was to evaluate the thermal field produced with monopolar and bipolar radiofrequency probes located at increasing heights from the target treatment site. TYPE OF STUDY: Experimental study. METHODS: Two bipolar (ACD-50, ArthroCare, Sunnyvale, CA; VAPR-TC, Mitec Surgical Products, Westwood, MA) and one monopolar (Vulcan TAC-C II, Oratec Interventions, Menlo Park, CA) radiofrequency probes were placed in a screw-driven stage that allowed for 0.25-mm incremental height-position changes. ArthroCare ACD-50 was evaluated at settings 2 and 8. The Mitek VAPR-TC was evaluated at setting 65 degrees C and V2-20 desiccation mode. The Oratec Vulcan TAC-C II system was evaluated at preset 2, power 15, set temperature 70 degrees C. The RF-probes were evaluated at variable distances from 0 to 2 mm. A fluoroptic thermometer was used to evaluate the temperatures within a room temperature 0.9% normal saline arthroscopic simulation chamber. RESULTS: The ACD-50 setting 2 at 0 mm was 89.1 degrees C; at 0.5 mm, 71.2 degrees C; and at 2 mm it was 37.3 degrees C. The ACD-50 setting 8 at 0 mm was 87.3 degrees C; at 0.5 mm, 42.5 degrees C; and at 2 mm, 33.6 degrees C. The Mitek VAPR-TC at 0 mm was 53.1 degrees C; at 0.5 mm, 42.5 degrees C; and at 2 mm, 26.8 degrees C. The Oratec Vulcan at 0 mm was 73.9 degrees C; at 0.5 mm, 60.3 degrees C; and at 2 mm, 29.0 degrees C. Each of these radiofrequency systems produced characteristic thermal fields at these settings. CONCLUSIONS: The temperature decreases with increasing distance characteristically for each radiofrequency probe. This is clinically important because altering radiofrequency probe location may cause large variations in articular cartilage thermal exposure.

Effects of electrical shielding and salt concentration on microwave heating in cylindrical containers.

Time-temperature distributions in water and salt solutions were collected in a cylindrical container with and without electrical top shielding during microwave heating. A cold spot was found to exist for both water and salt solutions close to the bottom of the container with and without electrical top shielding. Surface heating was observed in unshielded salt solutions and resulted in a stagnant layer close to the top of the container. Surface heating was eliminated in salt solutions with electrical shielding at the top of the container. Flow profiles within the container were monitored using a potassium permanganate dye tracer and a video camera. The flow profiles for water showed an upward flow in the central region and a descending flow along the side walls. An upward flow along the side walls and a downward flow along the central axis was observed for salt solutions.

Absorption of 193- and 213-nm laser wavelengths in sodium chloride solution and balanced salt solution.

OBJECTIVE: To determine absorption coefficients for sodium chloride solution (saline) and balanced salt solution at the 193- and 213-nm laser wavelengths. METHODS: Absorption coefficients were obtained for each of the component species found in balanced salt solution. This was achieved by measuring laser pulse transmission through solutions of varying concentration. The experiments were repeated using the 193-nm excimer and 213-nm solid-state laser wavelengths. Results for each species were then used to obtain an overall absorption coefficient and penetration depth for balanced salt solution and 0.9% sodium chloride solution. RESULTS: Absorption coefficients in balanced salt solution for the 193- and 213-nm wavelengths were found to be 140 and 6.9 cm(-1), respectively. In 0.9% sodium chloride solution, the absorption coefficient was 81 cm(-1) at 193 nm and 0.05 cm(-1) at 213 nm. At 193 nm, absorption in balanced salt solution was dominated by sodium chloride. Sodium citrate emerged as the dominant species of absorption at 213 nm. CONCLUSIONS: For the species investigated, we found reduced absorption for the longer wavelength of 213 nm. While the difference in wavelength between 193 and 213 nm is within about 10%, the respective molar absorption coefficients varied by 1 to 4 orders of magnitude. This indicates that predictions for the wavelength-dependent changes of absorption coefficients of other solutions are unreliable. CLINICAL RELEVANCE: Fluid placed on the surface of the cornea during keratorefractive surgery has proved to be a barrier to ablation for the 193-nm wavelength. The increased penetration depth through sodium chloride solution and balanced salt solution for the longer 213-nm laser wavelength may mean that these solutions cannot be used as a masking agent for keratorefractive procedures performed with this wavelength.

Radiation chemistry of physiological saline reinvestigated: evidence that chloride-derived intermediates play a key role in cytotoxicity.

Contrary to common belief, hydrogen peroxide (H2O2) and hypochlorite (HOCl) are not produced continuously and independently during the irradiation of buffer solution containing chloride. Different buildup and decay reactions are involved in a complex interaction of these substances during irradiation. Which of the species predominates is determined by the parameters of the solution. The amount of either compound detectable after irradiation depends on the dissolved gas (O2, N2O or N2), on the pH value and to some extent on the presence of catalytic metals: Under slightly acidic conditions, low oxygen content and high generation rates of OH radicals, the only detectable species is hypochlorite; at high oxygen content and at pH values in the physiological range, hydrogen peroxide is the main detectable product. However, H2O2 and HOCl react with each other in a pH-dependent way, yielding the stable products O2 and Cl-. This reaction limits the expected lifetime of both species in aqueous solution to some tens of seconds. Therefore, analysis of the sample solution after irradiation determines only the substance that was present in greater relative concentration at the termination of irradiation. Such analysis, however, does not allow conclusions about the processes that occurred during irradiation. We have investigated the decay and formation reactions of H2O2 and HOCl under all relevant irradiation conditions and found evidence that the formation and further reaction of HOCl-, the precursor of HOCl, is of central importance even in cases where no significant amounts of H2O2 or HOCl are detectable after irradiation. We discuss the consequences of these results for the cytotoxicity observed after irradiation of cells suspended in physiological saline and conclude that analogous processes must also be relevant for irradiations under in vivo conditions.

Influence of the dielectric property on microwave oven heating patterns: application to food materials.

Patterns of power absorption in a microwave oven for a range of dielectric properties of relevance to food processing were investigated. The governing Maxwell's equations with boundary conditions and a TE10 excitation were solved using a finite element method. Food properties were varied from values at their frozen state to values at high temperatures, as would be typical in a thawing process. For low-loss materials such as frozen foods, the high quality factor makes the heating significantly higher only when the size and shape of the load permit a dielectric cavity resonance in the load. Otherwise, the heating pattern will follow the modal electric field pattern of the oven. For moderate loss materials, the patterns will come from the modes of the dielectric cavity. The bandwidths of these modes are larger than the low-loss situation and their overlap results in a heating pattern that is somewhat more uniform. For high-loss materials, the concept of modes is no longer useful as the very large number of modes strongly overlap. The rapidly decaying field and power loss in the high-loss material can probably be characterized as an exponential decay.

On the cytotoxicity of irradiated media. To what extent are stable products of radial chain reactions in physiological saline responsible for cell death?

In a previous publication (Czapski et al. 1992) we reported that HOCl accounts for the toxicity of irradiated phosphate-buffered saline towards Escherichia coli bacterial cells. We have now investigated the respective toxicities towards lambda phage and mammalian cells. For phage, as with bacteria, cytotoxicity of the irradiated media seems to derive from HOCl without detectable contribution of H2O2. Mammalian cells (V79 CHO), in contrast, are more sensitive to H2O2 than to HOCl. Both agents, however, are not able to account quantitatively for the toxicity of irradiated solutions towards V79 cells; a hitherto unidentified chlorine/oxygen derivative--being formed in the sub-micromolar concentration range--is suggested to be responsible for toxicity in the case of eukaryotes.