Bunsen Valve Research Articles

Valvular mechanisms in antecubital cysts of rheumatoid arthritis.

AbstractTwo further cases of antecubital cysts resulting from rheumatoid arthritis are reported, both having valvular mechanisms permitting synovial fluid to pass from the elbow joint to the cyst but not the reverse. Rice bodies and synovial villous proliferation act as ball‐valves and the long neck of some cysts may act as Bunsen valves. One synovial cyst was successfully excised, while another underwent spontaneous regression after successful surgery at the wrist restored more nearly normal prontation and spination of the forearm.

Evaluation of Forages in the Laboratory. II. Simplified Artificial Rumen Procedure for Obtaining Repeatable Estimates of Forage Nutritive Value1,2

Summary The usual artificial rumen procedure has been simplified and adapted to give repeatable estimates of forage nutritive value. A 1-g sample of the ground forage was fermented in a 125-ml Erlenmeyer flask containing 30ml of McDougall's artificial sheep saliva adjusted to pH 6.7 and 25ml of strained rumen fluid obtained from a fistulated cow fed and managed in a standardized manner. Immediately after the addition of all contents the flask was flushed with CO 2 , capped with a Bunsen valve, and incubated at 39C for 24 hr. The per cent forage cellulose digested in this manner was significantly correlated with TDN, DDM, DE (calories per gram), and the digestion coefficient of energy determined in conventional animal digestibility trials. The artificial rumen method and prediction equation given in this paper yielded DE estimates on 19 forages which, when compared with the animal DE values, showed a coefficient of variation of 5.2%. The inclusion of a standard forage in each trial allowed adjustments to be made so that cellulose digestion obtained on two different days had a coefficient of variation of only 1.59%. It was found that the crude protein and digestible protein content of hays are highly correlated (r = 0.999) and that the latter could be estimated from the former with a resultant standard error of 0.25 and coefficient of variation of 2.26%.

Measurement of the Respiratory Quotient of Plant Tissues in a Constant Gaseous Environment

In the course of plant physiological investigations it is often necessary to determine the respiratory activity of living tissues. The rate of carbon dioxide evolution has been used frequently as an index of respiration since it is relatively easy to measure. Under some conditions, however, the carbon dioxide released does not reflect certain biochemical changes associated with respiration which may be more closely correlated with oxygen absorption. If both gases are measured simultaneously, and the respiratory quotient (CO2/O2) calculated, a better interpretation of attendant phenomena may be given than if an analysis is made of only one gaseous component of the system. For example, erroneous conclusions may be drawn concerning the influence of low oxygen tensions, and the effects of various absorbed salts on the formation of organic acids in excised barley roots when C02 measurements alone are used as a basis for measuring the respiratory processes. Many methods for determining the respiratory quotients of living tissues have been proposed according to which samples of gas were withdrawn from an enclosed chamber and then subsequently analyzed for carbon dioxide and oxygen. Objections to these methods were based on changes in composition of the gaseous environment during the experimental period and in the necessity of great accuracy in the analytical estimations. Major improvements were developed by Fernandez (2), who provided a closed system with a Bunsen valve pump for circulating the gases through alkali towers to absorb the carbon dioxide, and an oxygen generator controlled by an operator to replace electrolytically an oxygen deficit indicated by a manometer. His apparatus was adopted in a slightly modified manner by Wetzel (7) and more recently in revised form by Bennet-Clark (1). The latter investigator introduced a non-pulsating pump and the automatic addition of

Use of the Bunsen Valve in Connection with a Filter Pump.

Use of the Bunsen Valve in Connection with a Filter Pump.