Use of the ultrasonic cavitation in wool dyeing process: Effect of the dye-bath temperature

The present work aims to study the effect of the liquid temperature on the performance of ultrasounds (US) in a dyeing process. The approach was both theoretical and experimental. In the theoretical part the simplified model of a single bubble implosion is used to demonstrate that the "maximum implosion pressure" calculated with the well known Rayleigh-Plesset equation for a single bubble can be correlated with the cavitation intensity experimentally measured with an Ultrasonic Energy Meter (by PPB Megasonics). In particular the model was used to study the influence of the fluid temperature on the cavitation intensity. The "relative" theoretical data calculated from the implosion pressure were satisfactorily correlated with the experimental ones and evidence a zone, between 50 and 60°C, were the cavitation intensity is almost constant and still sufficiently high. Hence an experimental part of wool dyeing was carried out both to validate the previous results and to verify the dyeing quality at low temperatures (40-70°C) in presence of US. A prototype dyeing equipment able to treat textile samples with US system of 600W power, was used. The dyeing performances in the presence and absence of US were verified by measuring ΔE (colour variation), R_e,% (reflectance percentage), K/S (colour strength) and colour fastness. The US tests performed in the temperature range of 40-70°C were compared with the conventional wool dyeing at 98°C. The obtained results show that a temperature close to 60°C should be chosen as the recommended US dyeing condition, being a compromise between the cavitation intensity and the kinetics which rules the dyestuff diffusion within the fibres.

Mapping of cavitational activity in a pilot plant dyeing equipment

A large number of papers of the literature quote dyeing intensification based on the application of ultrasound (US) in the dyeing liquor. Mass transfer mechanisms are described and quantified, nevertheless these experimental results in general refer to small laboratory apparatuses with a capacity of a few hundred millilitres and extremely high volumetric energy intensity. With the strategy of overcoming the scale-up inaccuracy consequent to the technological application of ultrasounds, a dyeing pilot-plant prototype of suitable liquor capacity (about 40 L) and properly simulating several liquor to textile hydraulic relationships was designed by including US transducers with different geometries. Optimal dyeing may be obtained by optimising the distance between transducer and textile material, the liquid height being a non-negligible operating parameter. Hence, mapping the cavitation energy in the machinery is expected to provide basic data on the intensity and distribution of the ultrasonic field in the aqueous liquor. A flat ultrasonic transducer (absorbed electrical power of 600 W), equipped with eight devices emitting at 25 kHz, was mounted horizontally at the equipment bottom. Considering industrial scale dyeing, liquor and textile substrate are reciprocally displaced to achieve a uniform colouration. In this technology a non uniform US field could affect the dyeing evenness to a large extent; hence, mapping the cavitation energy distribution in the machinery is expected to provide fundamental data and define optimal operating conditions. Local values of the cavitation intensity were recorded by using a carefully calibrated Ultrasonic Energy Meter, which is able to measure the power per unit surface generated by the cavitation implosion of bubbles. More than 200 measurements were recorded to define the map at each horizontal plane positioned at a different distance from the US transducer; tap water was heated at the same temperature used for dyeing tests (60°C). Different liquid flow rates were tested to investigate the effect of the hydrodynamics characterising the equipment. The mapping of the cavitation intensity in the pilot-plant machinery was performed to achieve with the following goals: (a) to evaluate the influence of turbulence on the cavitation intensity, and (b) to determine the optimal distance from the ultrasound device at which a fabric should be positioned, this parameter being a compromise between the cavitation intensity (higher next to the transducer) and the US field uniformity (achieved at some distance from this device). By carrying out dyeing tests of wool fabrics in the prototype unit, consistent results were confirmed by comparison with the mapping of cavitation intensity.

Washing off intensification of cotton and wool fabrics by ultrasounds

Wet textile washing processes were set up for wool and cotton fabrics to evaluate the potential of ultrasound transducers (US) in improving dirt removal. The samples were contaminated with an emulsion of carbon soot in vegetable oil and aged for three hours in fan oven. Before washing, the fabrics were soaked for 3 min in a standard detergent solution and subsequently washed in a water bath. The dirt removal was evaluated through colorimetric measurements. The total color differences ΔE of the samples were measured with respect to an uncontaminated fabric, before and after each washing cycle. The percentage of ΔE variation obtained was calculated and correlated to the dirt removal. The results showed that the US transducers enhanced the dirt removal and temperature was the parameter most influencing the US efficiency on the cleaning process. Better results were obtained at a lower process temperature.

A prospective evaluation of the effect of activated charcoal before oral N-acetylcysteine in acetaminophen overdose

STUDY OBJECTIVE

To evaluate whether activated charcoal (AC) reduces the efficacy of subsequent oral N-acetylcysteine therapy during acute acetaminophen overdose.

DESIGN

Prospective observational case series of all acute acetaminophen overdoses reported to three certified regional poison centers. TYPES OF PATIENTS: All patients with acute acetaminophen overdose in whom N-acetylcysteine therapy was initiated within 16 hours after ingestion.

INTERVENTIONS

All patients were treated with oral N-acetylcysteine therapy for 72 hours. The decision to use AC was left to the treating physician without input from the investigator.

MEASUREMENTS AND RESULTS

One hundred twenty-two patients were evaluated. Maximum recorded SGOT levels of more than 125 U/mL were defined as evidence of hepatotoxicity. AC was used in addition to N-acetylcysteine in 82 of 122 patients. Hepatotoxicity developed in four of 82 patients who received AC versus ten of 40 patients who did not receive AC (P < .005). An increasing dose of N-acetylcysteine provided no additional benefit (P > .05). Spacing the administration of AC and oral N-acetylcysteine less than or more than two hours apart did not affect outcome (P > .05).

CONCLUSION

Administration of AC before the administration of oral N-acetylcysteine in acetaminophen overdose does not reduce the efficacy of N-acetylcysteine therapy and may provide some additional hepatoprotective benefit. The practice of increasing the dose of oral N-acetylcysteine therapy after the administration of AC appears unwarranted.

Survival following hydrofluoric acid ingestion

Systemic toxicity after significant dermal exposure to hydrofluoric acid includes rapid development of hypocalcemia and hyperkalemia, leading to ventricular fibrillation. Similar dysrhythmias have occurred in patients after ingestion of sodium fluoride-containing compounds. Ingestion of hydrofluoric acid could induce similar cardiac toxicity; however, reported cases of hydrofluoric acid ingestion rarely have been described, and the rapid death of these patients has not allowed verification of this hypothesis. On two separate occasions, a 70-year-old woman ingested up to 2 oz of a 8% hydrofluoric acid-containing solution. Recurrent ventricular fibrillation with concurrent hypocalcemia and hypomagnesemia complicated her first episode, whereas a more aggressive administration of calcium and magnesium may have prevented dysrhythmias in the second episode. Survival from ventricular fibrillation after hydrofluoric acid ingestion has not been reported previously and suggests a role for aggressive empiric calcium and magnesium replacement.

Diltiazem overdose: case report and review

We present a case of diltiazem overdose in which the patient ingested 4.2 grams in an apparent suicide attempt. He arrived in the emergency department two hours postingestion with a blood pressure of 60/40 torr and a heart rate of 62 beats/min in a junctional rhythm. Intervention included activated charcoal, gastric lavage, intravenous fluids, calcium (both chloride and gluconate), dopamine, and atropine with improvement in vital signs. Diltiazem levels were obtained and half-life calculated. This ingestion is one of the largest reported in the literature and is remarkable in that the patient recovered without pacing or other extraordinary measures. All eight previously published cases of diltiazem overdose, including all unpublished reports to the manufacturer, are reviewed and their management strategies examined. Successful treatment in which recovery has occurred in less than 48 hours, includes pressors, calcium, glucagon, pacing, and charcoal hemoperfusion. A strategy for emergency physicians to use when approaching this problem is suggested from the review.

How serious is the radon problem?

In the last year or two, a vast array of radon-detection kits has appeared in stores and catalogs. The authors explain what radon is and why it has captured the interest of the American public. They also examine the extent and significance of the radon problem and suggest solutions for homes that are found to have a high concentration.

The effect of fluid volume on syrup of ipecac emesis time

Large volumes of fluid have been recommended to aid rapid ipecac-induced emesis, however, large volume intake may also have deleterious effects. We prospectively studied 121 children treated at home by a regional poison center to determine if a relationship existed between fluid volume and time to emesis. These children were treated in the usual manner except that parents were asked to measure the volume of fluid given and to note the time that fluid was given and the time of first emesis. The time ranged from 6 to 58 minutes (mean 20.6) with two who failed to respond and the volume ranged from 0 to 28 ounces (mean 6.7 ounces). In children who respond to ipecac, there is no significant relationship between the amount of fluid given and the time until emesis. We conclude that the traditional recommendation of forcing fluid with syrup of ipecac does not hasten emesis in children.