Measurement of heterogeneous reaction rates during indium-mediated allylation.

Indium-mediated allylation provides remarkable stereo- and regioselectivity, and it proceeds easily and in high yield in aqueous solutions. In spite of its widespread use, there have been few fundamental studies of this reaction. We have developed a photomicrographic technique for measuring rates of reaction of allyl halides at indium surfaces, and we describe the mathematical model for discriminating between diffusion and kinetic control.

One-dimensional ordering of ultra-low-density ion beams in a storage ring.

The two-particle model, first introduced by Hasse, is employed to predict the beam temperature at which a one-dimensional ordered state of ions will be established in a cooler storage ring. The proposed state does not have the ions (in the beam frame) at rest, but simply has them not passing each other; i.e.

Subluminous phase velocity of a focused laser beam and vacuum laser acceleration.

It has been found that for a focused laser beam propagating in free space, there exists, surrounding the laser beam axis, a subluminous wave phase velocity region. Relativistic electrons injected into this region can be trapped in the acceleration phase and remain in phase with the laser field for sufficiently long times, thereby receiving considerable energy from the field. Optics placed near the laser focus are not necessary, thus allowing high intensities and large energy gains.

Body morphology and the speed of cutaneous rewarming.

Background: Infants and children cool quickly because their surface area (and therefore heat loss) is large compared with their metabolic rate, which is mostly a function of body mass. Rewarming rate is a function of cutaneous heat transfer plus metabolic heat production divided by body mass. Therefore, the authors tested the hypothesis that the rate of forced-air rewarming is inversely related to body size.

Experimental determination of heat flow parameters during induction of general anesthesia.

Background: Alterations in body temperature result from changes in tissue heat content. Heat flow is a complex function of vasomotor status and core, peripheral, and ambient temperatures. Consequently it is difficult to quantify specific mechanisms responsible for observed changes in body heat distribution.

Polyunsaturated fatty acid regulation of gene expression.

For the past three decades, polyunsaturated fatty acids (PUFA) have been recognized as important energy sources and membrane components. PUFA also play key roles in many cellular events, such as gene regulation. Most recently, research has focused on identifying the mechanisms by which PUFA modulate gene transcription, mRNA stability and cellular differentiation.

Regulation of stearoyl-CoA desaturase 1 mRNA stability by polyunsaturated fatty acids in 3T3-L1 adipocytes.

The effects of arachidonic acid (20:4, n-6) and other fatty acids on the expression of stearoyl-CoA desaturase gene 1 were investigated in fully differentiated 3T3-L1 adipocytes. Treatment of 3T3-L1 adipocytes with arachidonic acid resulted in a decrease in stearoyl-CoA desaturase (Scd) enzyme activity and scd1 mRNA. Arachidonic acid did not alter the transcription of the scd1 gene, whereas the half-life of the scd1 mRNA was reduced from 25.

A model cell line to study regulation of stearoyl-CoA desaturase gene 1 expression by insulin and polyunsaturated fatty acids.

Insulin and polyunsaturated fatty acids (PUFAs) regulate the expression of SCD1 gene in mouse liver. Accordingly, we examined the insulin and PUFA regulation of SCD1 gene expression in H2.35 cells.

Heat flow and distribution during induction of general anesthesia.

Background: Core hypothermia after induction of general anesthesia results from an internal core-to-peripheral redistribution of body heat and a net loss of heat to the environment. However, the relative contributions of each mechanism remain unknown. The authors evaluated regional body heat content and the extent to which core hypothermia after induction of anesthesia resulted from altered heat balance and internal heat redistribution.

Heat loss during surgical skin preparation.

Background: Hypothermia develops rapidly during the 1st h of anesthesia and results in part from evaporative heat loss during surgical skin preparation. The authors tested the hypothesis that evaporation of skin preparation solution contributes significantly to hypothermia.

Methods: Five healthy, unanesthetized volunteers were studied in a 22 +/- 0.

Leg heat content continues to decrease during the core temperature plateau in humans anesthetized with isoflurane.

Background: Sufficient hypothermia during anesthesia provokes thermoregulatory responses, but the clinical significance of these responses remains unknown. Nonshivering thermogenesis does not increase metabolic heat production in anesthetized adults. Vasoconstriction reduces cutaneous heat loss, but the initial decrease appears insufficient to cause a thermal steady state (heat production equaling heat loss).

Perioperative thermal insulation.

To determine the efficacy of passive insulators advocated for prevention of cutaneous heat loss, we determined heat loss in unanesthetized volunteers covered by one of the following: a cloth "split sheet" surgical drape; a Convertors disposable-paper split sheet; a Thermadrape disposable laparotomy sheet; an unheated Bair Hugger patient-warming blanket; 1.5-mil-thick plastic hamper bags; and a prewarmed, cotton hospital blanket. Cutaneous heat loss was measured using 10 area-weighted thermal flux transducers while volunteers were exposed to a 20.