Ppm In Combination Research Articles

Design and operation of a preferential oxidation microdevice for a portable fuel processor

Microreactor technology creates opportunities for the development of miniature chemical devices, in which several unit operations are integrated. In this paper, we describe the design, model simulation, and experimental validation and operation of a microdevice for the preferential oxidation of carbon monoxide in hydrogen-rich reformate gas. The microdevice integrates two heat exchangers and one reactor, all consisting of welded stacks of microstructured plates. We show that the device is able to reduce the carbon monoxide concentration to 10 ppm in combination with a high heat recovery efficiency of 90%. The design of the microstructured plates was based on a combination of three-dimensional computational fluid dynamics simulations of the flow pattern and a two-dimensional heat transfer model, in which the flow pattern was approximated. An integral one-dimensional micro heat exchange model was then used to design the integrated device. This approach may be well suited for designing microstructured reaction systems.

Increased Efficacy of Bacillus thuringiensis subsp. kurstaki m Combination with Tannic Acid

We identified tannic acid as an inexpensive additive that increased the efficacy of sublethal concentrations of Bacillus thuringiensis subsp. kurstaki (Berliner). Tannic acid mimicked the active constituents contained in an aqueous, tannin-rich extract of Taxus baccata (L.) bark that retarded development of Heliothis virescens (F.) larvae at 10,000 ppm; most larvae remained in first and second stage when treated with 250-10,000 ppm of tannic acid. Instar development of Trichoplusia ni (Hübner) larvae was affected in a concentration-dependent manner by 2.5-500 ppm of tannic acid. In subsequent bioassays, tannic acid at 25-500 ppm in combination with B. thuringiensis (1.63 micrograms [AI]/ml diet) yielded mean mortalities of 57-75%, whereas treatments with B. thuringiensis alone produced 10% mortality. Mean mortalities in the 3.0, 4.5, and 6.75 micrograms (AI) B. thuringiensis per milliliter of diet treatments (5.5; 8.0, and 30%, respectively) were significantly higher in the presence of 250 and 2,500 ppm tannic acid; in these treatments we observed 78-94% mortality. Addition of tannic acid increased the activity of concentrations of 3-4.5 micrograms (AI) B. thuringiensis per milliliter of diet to approximately that of a concentration of 13 micrograms (AI) B. thuringiensis per milliliter of diet alone (85-95% mortality). Although deaths caused by a formulation of B. thuringiensis + tannic acid occurred more slowly than with high rates of B. thuringiensis alone, such formulations would have the advantages of arresting development, minimizing foliar damage, and decreasing the concentration of B. thuringiensis used.

Occupational dimethylformamide exposure. 3. Health effects of dimethylformamide after occupational exposure at low concentrations.

A factory survey was conducted in a plant where N,N-dimethylformamide (DMF) was in use during the production of polyurethane plastics and related materials. In all, 318 DMF-exposed workers (195 men and 123 women) and 143 non-exposed controls (67 men and 76 women) were examined for time-weighted average exposure (to DMF and other solvents by diffusive sampling), hematology, serum biochemistry, subjective symptoms, and clinical signs. Most of the exposed workers were exposed only to DMF, whereas others were exposed to a combination of DMF and toluene. DMF exposure in the former group was up to 7.0 ppm (geometric mean on a workshop basis), whereas it was up to 2.1 ppm in combination with 4.2 ppm toluene. Both hematology and serum biochemistry, results (including aspartate and alanine aminotransferases, gamma-glutamyl transpeptidase and amylase) were essentially comparable among the 3 groups. There was, however, a dose-dependent increase in subjective symptoms, especially during work, and in digestive system-related symptoms such as nausea and abdominal pain in the past 3-month period. The prevalence rate of alcohol intolerance complaints among male (assumedly) social drinkers was also elevated in relation to DMF dose.

Increase in sister chromatid exchange rates in association with occupational exposure to N,N-dimethylformamide.

The effects of occupational exposure to N,N-dimethylformamide (DMF) on sister chromatid exchange (SCE) rates were studied in peripheral lymphocytes from 22 DMF-exposed women (aged 22-52 years) in comparison with 22 sex-, age-, and residence-matched controls. All subjects were nonsmokers and nondrinkers as confirmed by medical interview. The 22 pairs were divided by the intensity of exposure to DMF into 3 subgroups of high-exposed (8 pairs with mean DMF exposure at 5.8 ppm), middle-exposed (5 pairs with DMF at 0.7 ppm in combination with toluene at 0.9 ppm), and low-exposed (9 pairs with DMF at 0.3 ppm). The SCE rates were significantly higher in the high (P less than 0.005) and middle (P less than 0.01) exposed than in their matched pairs, and the increase was related to the intensity of DMF exposure.

Effect of Sodium Nitrite and Origanum Oil on Growth and Toxin Production of Clostridium botulinum in TYG Broth and Ground Pork

Inhibition of Clostridium botulinum (strains A, B, and E) growth and toxin production by various concentrations of origanum oil and sodium nitrite was studied for both TYG broth and a model meat system. At concentrations of 100 and 200 ppm, origanum oil was effective in inhibiting C. botulinum growth in TYG broth. In addition, origanum oil acted synergistically with sodium nitrite in inhibiting C. botulinum growth in TYG broth. The inhibitory effect of origanum oil in the meat system was dramatically reduced and had a significant (p≤ 0.05) effect only when used at 400 ppm in combination with 50–100 ppm sodium nitrite.

Effect of Ethephon and Heat on the Growth and Yield of Edible Ginger

Abstract Preplant soak application of ethephon at 750 ppm in combination with a 51°C water soak for 10 min to ginger (Zingiber officinale Roscoe ‘Chinese’) rhizomes increased shoot number by 122% after 16 wk and rhizome weight by 38% at harvest, compared to 21° water-soaked rhizomes. The increase in rhizome weight was correlated with number of shoots per plant. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon).

Flowering in pineapple as influenced by ethephon and its combinations with urea and calcium carbonate

An investigation was carried out to increase the efficacy of ethephon by combining it with urea and calcium carbonate for induction of flowering in pineapple, with the main objective of lowering the concentration of ethephon. Ethephon at a concentration as low as 25 ppm in combination with urea (2%) and calcium carbonate (0.04%) was able to induce more than 90% flowering after 50 days of treatment. Addition of either urea or calcium carbonate increased the effectiveness of ethephon for induction of flowering. Ethephon treatments were found to be markedly superior to planofix and the control. In the case of the control, plants started flowering 250 days after treatment and completed it after 340 days. Apart from earlier flowering, ethephon treatments resulted in uniform ripening, and harvests were complete within 10 days, whereas in the control harvests continued for about 70 days. The increased efficacy of ethephon at a lower concentration for induction of flowering, with the addition of urea and calcium carbonate, is of great significance as this will lead to decreased costs and increased commercial use.

Use of Ethephon to Stimulate Red Color Without Hastening Ripening of ‘McIntosh’ Apples1

Abstract A regional experiment was conducted to determine if 2-chloroethylphosphonic acid (ethephon) could be used to increase red color of ‘McIntosh’ apples without stimulating fruit ripening. Ethephon was applied at 75 or 150 ppm in combination with succinic acid 2,2-dimethylhydrazide (SADH) and either 20 ppm naphthaleneacetic acid (NAA) or 10 ppm 2,4,5-trichlorophenoxypropionic acid (fenoprop). All combinations enhanced red color, but 150 ppm ethephon usually softened the fruit slightly. Following CA storage, apples treated with 150 ppm ethephron, or 75 ppm ethephon plus 20 ppm NAA, were slightly softer than ones sprayed with only SADH. Nevertheless, 5-member panels were generally unable to distinguish ripeness differences among the samples. We concluded that with careful restrictions, low concentrations of ethephon can be used to enhance red color without sacrificing fruit condition following storage.

A Benzothiadiazole Extends Cut Carnation Flower Life1

Abstract Immersion of cut carnation, Dianthus caryophyllus L. ‘Red Sim’ at the open, partially open or tight bud stage for 6-24 hours in 5-methyl-7-chloro-4-ethoxycarbonylmethoxy-2, 1, 3-benzothiadiazole (MCED) at 5 ppm in combination with 8-hydroxyquinoline sulfate (8HQS) at 200 ppm and 1.5% sucrose increased flower life. The greatest increase occurred when flowers were immersed in the solution at the partially open and tight bud stages for 12 to 24 hours.