CONTINUOUS-FLOW DILUTION OF SOIL SUSPENSIONS FOR MICROBIAL ASSAY

1960 ◽  
Vol 6 (5) ◽  
pp. 583-589 ◽  
Author(s):  
J. D. Menzies
Keyword(s):  
Soil Sample ◽  
Closed System ◽  
Continuous Flow ◽  
Optimum Number ◽  
Sterile Water ◽  
Soil Suspension ◽  
Water Flows ◽  
Glass Chamber ◽  
Microbial Assay

The principle of logarithmic dilution resulting from passage of a diluent through a solution in a closed system is used in an apparatus for obtaining samples of soil suspension of known dilution for microbial assay. The device consists of a 14-ml glass chamber containing a magnetic agitator. As sterile water flows through the chamber in which a soil sample has been placed, the dilution of the sample in the effluent depends upon the amount of water used. Samples of effluent can thus be collected for replicated plating at any desired dilution, or aliquots can be plated directly at dilution intervals selected so that some portion of the series will yield plates with the optimum number of colonies for counting. The method is simple and timesaving and should compare favorably in accuracy with conventional procedures.

Automated Micro Measurement of Glucose by Means of o-Toluidine

1969 ◽  
Vol 15 (12) ◽  
pp. 1162-1170 ◽  
Author(s):  
Robert E Wenk ◽  
Ronald J Creno ◽  
Valerie Loock ◽  
John Bernard Henry
Keyword(s):  
Cerebrospinal Fluid ◽  
Closed System ◽  
Continuous Flow ◽  
Reduction Method ◽  
Flow Analysis ◽  
Protein Precipitation ◽  
Ferricyanide Reduction ◽  
Continuous Flow Analysis

Abstract The method described is based on Dubowski’s o-toluidine procedure for the determination of glucose in plasma, serum, or cerebrospinal fluid. It utilizes the rapidity, precision, and closed system of continuous flow analysis of an unmodified AutoAnalyzer to substantially increase sensitivity and accuracy in the low range. The method is more specific than the ferricyanide reduction method. Protein precipitation or dialysis are unnecessary except for hemolyzed specimens and only 0.042 ml of sample are required. The method is inexpensive, easily performed, and compares favorably on a practical basis with enzymatic, reducing, and other aniline dye methods.

Impacts of matric suction equalization on small strain shear modulus of soils during air drying

2020 ◽  
Vol 57 (12) ◽  
pp. 1982-1997
Author(s):  
Thang Pham Ngoc ◽  
Behzad Fatahi ◽  
Hadi Khabbaz ◽  
Daichao Sheng
Keyword(s):  
Shear Modulus ◽  
Water Content ◽  
Soil Sample ◽  
Closed System ◽  
Small Strain ◽  
Matric Suction ◽  
Drying Process ◽  
Air Drying ◽  
Small Strain Shear Modulus ◽  
The Impact

In this study, a weight-control bender element system has been developed to investigate the impact of matric suction equalization on the measurement of small strain shear modulus (Gmax) during an air-drying process. The setup employed is capable of measuring the shear wave velocity and the corresponding Gmax of the soil sample in either an open system in which the soil sample evaporates freely or in a closed system that allows the process of matric suction equalization. The comparison between measurements of Gmax in the open and closed systems revealed underestimations of Gmax when matric suction equalization was ignored due to the nonuniform distribution of water content across the sample cross-sectional area. This study also investigated the time required for matric suction equalization tse to be established for samples with different sizes. The experimental results indicated two main mechanisms driving the matric suction equalization in a closed system during an air-drying process, namely the hydraulic flow of water and the flow of vapour. While the former played the key role when the micropores were still saturated at the high range of water content, effects of the latter increased and finally dominated when more air invaded the micropores at lower water contents.

COMMITTEE ON FETUS AND NEWBORN

PEDIATRICS ◽  
1966 ◽  
Vol 38 (1) ◽  
pp. 142-144
Author(s):  
Keyword(s):  
Organic Matter ◽  
Closed System ◽  
Nosocomial Infections ◽  
Sterile Water ◽  
Insufficient Evidence ◽  
Satisfactory Solution ◽  
Objective Information ◽  
Insurmountable Problem ◽  
Teflon Coating ◽  
Chemical Disinfection

THE Committee on Fetus and Newborn and consultants met in Chicago, Illinois, on October 23, 1965, to consider the problem of decontamination of fomites in neonatal units to reduce the incidence of nosocomial infections. It was agreed that there is insufficient evidence available to make authoritative recommendations for uniform procedures to deal with problems of decontamination of incubators, bassinets, respirators, and other equipment used in present day neonatal facilities. However, the participants suggested that certain statements could be made at this time which would serve to stimulate the interest of those concerned with the management of neonatal units and to emphasize the need to obtain objective information for a satisfactory solution to the problems posed. Agreement was reached on the following statements: 1. Emphasis must be placed on cleansing and housekeeping procedures. Chemical disinfection is not a substitute for mechanical scrubbing and removal of dirt or organic matter. Moreover, organic matter inactivates many chemical disinfectants. 2. Manufacturers of equipment used in the newborn nursery must be encouraged to design equipment which can be easily cleaned and disinfected. Adequate cleansing of occupied incubators poses an almost insurmountable problem; ingenious engineering solutions are badly needed. Component pants of intricate devices should be removable for easier cleaning. Teflon coating of surfaces would ease mechanical cleansing. Nebulizing equipment should use air which has passed through a bacterial filter, sterile water from freshly opened bottles, and a closed system for delivery of water to the nozzle. Nebulizers should be designed for easy disinfection, preferably sterilization.

scholarly journals The numbers of bacterial cells in field soils, as estimated by the ratio method

1934 ◽  
Vol 115 (795) ◽  
pp. 522-543 ◽  
Keyword(s):  
Soil Sample ◽  
Bacterial Population ◽  
Total Population ◽  
Ratio Method ◽  
Bacterial Cells ◽  
Soil Suspension ◽  
Plate Counts ◽  
The Media ◽  
Diverse Groups ◽  
Do So

It has long been recognized that the method of counting bacteria in a soil sample by means of plate counts is valueless as an estimate of the total bacterial population, although such counts have undoubted value in comparing two or more samples. The numbers obtained by this method represent only a small fraction of the total population. This is due mainly to the fact that no single plating medium will enable all the diverse groups of soil bacteria to multiply and produce colonies. Indeed, many types will not grow on any of the media commonly used for plate counts, and it is very uncertain whether those which do so are of main importance in carrying out biochemical changes in the soil itself. The number of colonies which appear is probably reduced further by the fact that, in some soils, many of the bacteria occur in clumps which would not easily be broken up in the process of making the soil suspension. These limitations of the plate method make it very important that a technique should be developed for making accurate estimates of the total bacterial content of a soil sample from direct microscope counts. The counting of bacteria in dried and stained films has become a recognized technique for milk (Breed, 1911). A comparison between plate and direct microscope counts of milk samples was made by Breed and Stocking (1920) and more recently by Buice (1934) who found that the numbers obtained by two methods were of the same order. With milk, however, most, if not all, of the organisms counted were of types capable of growing upon the plating medium used. The application of direct counting methods to bacteria in a soil sample is greatly complicated by the presence of the soil particles. These introduce difficulties in staining the film, in obtaining an even distribution of bacteria over the film, and in estimating the mass of soil examined.

Dual Gradient Drilling Will Control Shallow Hazards in Deepwater Environments

2009 ◽  
Author(s):  
Brandee A. Elieff ◽  
Jerome J. Schubert
Keyword(s):  
Shallow Water ◽  
Closed System ◽  
Drilling Fluid ◽  
Detection Methods ◽  
Methane Hydrates ◽  
Shallow Gas ◽  
Well Control ◽  
Water Flows ◽  
Shallow Water Flows ◽  
Dual Gradient

Currently the “Pump and Dump” method employed by Exploration and Production (E&P) companies in deepwater is simply not enough to control increasingly dangerous and unpredictable shallow hazards. “Pump and Dump” requires a heavy dependence on accurate seismic data to avoid shallow gas zones; the kick detection methods are slow and unreliable, which results in a need for visual kick detection; and it does not offer dynamic well control methods of managing shallow hazards such as methane hydrates, shallow gas and shallow water flows. These negative aspects of “Pump and Dump” are in addition to the environmental impact, high drilling fluid (mud) costs and limited mud options. Dual gradient technology offers a closed system, which improves drilling most simply because the mud within the system is recycled. The amount of required mud is reduced, the variety of acceptable mud types is increased and chemical additives to the mud become an option. This closed system also offers more accurate and faster kick detection methods in addition to those that are already used in the “Pump and Dump” method. It has the potential to prevent the formation of hydrates by adding hydrate inhibitors to the drilling mud. And more significantly, this system successfully controls dissociating methane hydrates, over pressured shallow gas zones and shallow water flows. Dual gradient technology improves deepwater drilling operations by removing fluid constraints and offering proactive well control over dissociating hydrates, shallow water flows and over pressured shallow gas zones. There are several clear advantages for dual gradient technology: economic, technical and significantly improved safety, which is achieved through superior well control.

Catalyst- and oxidant-free electrochemical para-selective hydroxylation of N-arylamides in batch and continuous-flow

2020 ◽  
Vol 22 (19) ◽  
pp. 6437-6443
Author(s):  
Cheng-Kou Liu ◽  
Meng-Yi Chen ◽  
Xin-Xin Lin ◽  
Zheng Fang ◽  
Kai Guo
Keyword(s):  
Ammonium Salt ◽  
Quaternary Ammonium ◽  
Continuous Flow ◽  
Quaternary Ammonium Salt ◽  
Selective Hydroxylation

A catalyst-, oxidant-, acidic solvent- and quaternary ammonium salt-free electrochemical para-selective hydroxylation of N-arylamides at rt in batch and continuous-flow was developed.

A closed system audio helmet for monkeys.

1969 ◽  
Author(s):  
Leslie W. Dalton ◽  
Wenden W. Henton ◽  
Henry L. Taylor ◽  
James N. Allen
Keyword(s):  
Closed System
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