Publications by authors named "Rubin He"

Flexible and stretchable electronic devices are subject to failure because of vulnerable circuit interconnections. We develop a low-voltage (1.5 to 4.

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Lactic acid is the inhibitory agent in yoghurt responsible for the inhibition of Salmonella typhimurium. Casein, however, may exert a protective effect toward the survival of the salmonella in acid-milk products. Salmonella typhimurium was found to die-off 21.

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The fate of phenol carbon at phenol concentrations ranging from 1 ng/ml to 1 microgram/ml was determined in freshwater samples. Approximately 20% of the parent phenol was incorporated into trichloroacetic acid-precipitable material by the microorganisms capable of mineralizing phenol. There was no apparent lag period before phenol incorporation commenced, and incorporation was complete within 2 h at all concentrations tested.

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A method was developed to enumerate the procaryotic and eucaryotic phenol-mineralizing microorganisms present in samples of fresh water. Sixty-five percent or greater mineralization of [U-14C]phenol was considered a positive tube (contained phenol-mineralizing microorganisms) in the most-probable-number technique. Replicate most-probable-number tubes contained no microbial inhibitors, streptomycin and tetracycline, or cyclohexamide and nystatin plus 200 pg to 100 micrograms of phenol per ml.

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A sensitive and rapid method was developed to measure the mineralization of C-labeled organic compounds at picogram-per-milliliter or lower levels in samples of natural waters and sewage. Mineralization was considered to be equivalent to the loss of radioactivity from solutions. From 93 to 98% of benzoate, benzylamine, aniline, phenol, and 2,4-dichlorophenoxyacetate at one or more concentrations below 300 ng/ml was mineralized in samples of lake waters and sewage, indicating little or no incorporation of carbon into microbial cells.

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The rates of mineralization of phenol, benzoate, benzylamine, p-nitrophenol, and di(2-ethylhexyl) phthalate added to lake water at concentrations ranging from a few picograms to nanograms per milliliter were directly proportional to chemical concentration. The rates were still linear at levels of <1 pg of phenol or p-nitrophenol per ml, but it was less than the predicted value at 1.53 pg of 2,4-dichlorophenoxyacetate per ml.

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We determined how lactic acid inhibits growth of Salmonella typhimurium in yogurt. This inhibition was demonstrated by microscopic examination not to be due to bacteriolysis. Neither growth nor metabolic activity could be initiated after cells were washed in phosphate buffer and exposed to 1.

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The inhibitory nature of yogurt against contaminating microorganisms has been studied extensively. Nevertheless, the factors responsible for the death of Salmonella typhimurium in yogurt have not been elucidated. An understanding of these factors is important for the determination of yogurt's safety to consumer health.

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Toxicological model for a two-acid system.

Appl Environ Microbiol

October 1978

Article Synopsis
  • Lactic and acetic acids showed a small synergistic effect when used together against Salmonella typhimurium, meaning they worked slightly better together than they do alone.
  • This conclusion was drawn from a modified toxicological model, which is a study method used to test the effects of substances on organisms.
  • The findings suggest potential for these acids in controlling Salmonella in food safety applications.
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Article Synopsis
  • The supernatant fluid from cultures of E. coli W-11, a pur E mutant, can prevent growth inhibition of E. coli B when using adenine or adenosine, with adenine being more effectively blocked.
  • Over 90% of the biologically active component of the supernatant was found in the anionic fraction after treatment, while the cationic fraction, rich in AIRS, did not have the same inhibitory prevention capability.
  • The study identifies that the protective compound is an intermediate in thiamine biosynthesis (called int-1) and demonstrates its stability under various conditions, providing a new understanding of its role in synthesizing thiamine.
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