Fitting the environment by modifying water structure

1968 ◽  
Vol 171 (1022) ◽  
pp. 59-65 ◽  
Keyword(s):  
Molecular Weight ◽  
Surface Water ◽  
Solar System ◽  
Water Structure ◽  
Low Molecular Weight ◽  
Complex Structures ◽  
Complex Processes ◽  
Relative Neglect

Earth is distinguished from other planets of the solar system by an abundance of surface water. Water is a part of man’s environment from the womb onwards and we tend to take it and its properties completely for granted. It is too seldom consciously regarded as a significant metabolite, an essential substrate for very many enzymes, but tends to be thought of merely as an end product of the divertingly complex processes of oxidation in the cell. Its low molecular weight and the facts that it comes out of a tap, and that its formula is one of the two or three known to non-scientists all perhaps contribute to its relative neglect by a science occupied with unravelling the complex structures and functions of polymers. Yet water itself is a polymer, perhaps the most unstable and structurally labile we know of at present.

scholarly journals Assessing pre-adsorption time impact on ultrafiltration performance for surface water treatment

2017 ◽  
Vol 18 (3) ◽  
pp. 950-955
Author(s):  
Bo Gui ◽  
Qingqing Zhao ◽  
Junxia Liu ◽  
Zhihong Wang ◽  
Huaqiang Chu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Liquid Chromatography ◽  
Activated Carbon ◽  
Water Treatment ◽  
Surface Water ◽  
Membrane Fouling ◽  
Low Molecular Weight ◽  
Raw Water ◽  
Adsorption Time ◽  
Surface Water Treatment

Abstract This study was to assess the effect of powdered activated carbon (PAC) pre-adsorption time on ultrafiltration performance for surface water treatment. Experimental results demonstrated that membrane fouling could be mitigated by extending the pre-adsorption time. The molecular weight (MW) distribution of water samples was determined by liquid chromatography – organic carbon detector (LC-OCD) and results showed that the mechanism of PAC controlling fouling was attributed to a decrease in the low molecular weight (LMW) fraction of raw water via extending the pre-adsorption time. Fouling indexes (FIs) were used to evaluate membrane fouling potential and the results showed that polysaccharides (PS) and proteins (PN) were greatly responsible for membrane fouling. Therefore, prolonging the PAC pre-adsorption time and decreasing the PS and PN content in raw water are the main measurement for the alleviation of membrane fouling when PAC is used as the pretreatment in waterworks.

scholarly journals Demonstrating Aqueous-Phase Low-Molecular-Weight-Gel Wicking of Oil for the Remediation of Oil Spilled into Surface Water

Langmuir ◽  
2020 ◽  
Vol 36 (44) ◽  
pp. 13155-13165
Author(s):  
Daniel J. Walls ◽  
Emilie Espitalié ◽  
Gabriel Hum ◽  
Jun Chen ◽  
Michael Gattrell ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Surface Water ◽  
Aqueous Phase ◽  
Low Molecular Weight

Assessment on the Health Risk of Low-Molecular-Weight Polycyclic Aromatic Hydrocarbons (PAHs) in Surface Water of Lake Baiyangdian

2013 ◽  
Vol 864-867 ◽  
pp. 840-843
Author(s):  
Wei Guo ◽  
Yao Feng
Keyword(s):  
Molecular Weight ◽  
Drinking Water ◽  
Surface Water ◽  
Health Risk ◽  
Risk Level ◽  
Low Molecular Weight ◽  
Potential Health ◽  
Polycyclic Aromatic ◽  
Carcinogenic Effects ◽  
Lake Baiyangdian

Low-molecular-weight (LMW) PAHs in surface water of Lake Baiyangdian were determined to assess the potential health risk when using as drinking water for children and adults. The concentration of LMW PAHs in surface water were in the range of 77.26-760.16 ng L-1. Compared with similar results reported around the world, the level of LMW PAHs in this study was in the mid-range. The analysis of health risk indicated that risks from LMW PAHs in most part of the lake would not be risky to human health according to the acceptable risk level, while carcinogenic effects caused by LMW PAHs might occur if drinking water from Nanliuzhuang (NLZ), Shaochedian (SCD) and Laowangdian (LWD). Risks of LMW PAHs for children were apparently much higher than those caused by LMWs PAHs for adults.

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment

Venous thromboembolism in a general hospital. An update with low molecular weight heparin prophylaxis

VASA ◽  
2007 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
Schulz ◽  
Kesselring ◽  
Seeberger ◽  
Andresen
Keyword(s):  
Molecular Weight ◽  
Pulmonary Embolism ◽  
Venous Thromboembolism ◽  
Low Molecular Weight ◽  
Trauma Patients ◽  
Vte Prophylaxis ◽  
Vein Thrombosis ◽  
Patients At Risk ◽  
Hospital Stays ◽  
Event Rates

Background: Patients admitted to hospital for surgery or acute medical illnesses have a high risk for venous thromboembolism (VTE). Today’s widespread use of low molecular weight heparins (LMWH) for VTE prophylaxis is supposed to have reduced VTE rates substantially. However, data concerning the overall effectiveness of LMWH prophylaxis is sparse. Patients and methods: We prospectively studied all patients with symptomatic and objectively confirmed VTE seen in our hospital over a three year period. Event rates in different wards were analysed and compared. VTE prophylaxis with Enoxaparin was given to all patients at risk during their hospital stay. Results: A total of 50 464 inpatients were treated during the study period. 461 examinations were carried out for symptoms suggestive of VTE and yielded 89 positive results in 85 patients. Seventy eight patients were found to have deep vein thrombosis, 7 had pulmonary embolism, and 4 had both deep venous thrombosis and pulmonary embolism. The overall in hospital VTE event rate was 0.17%. The rate decreased during the study period from 0.22 in year one to 0,16 in year two and 0.13 % in year three. It ranged highest in neurologic and trauma patients (0.32%) and lowest (0.08%) in gynecology-obstetrics. Conclusions: With a simple and strictly applied regimen of prophylaxis with LMWH the overall rate of symptomatic VTE was very low in our hospitalized patients. Beside LMWH prophylaxis, shortening hospital stays and substantial improvements in surgical and anasthesia techniques achieved during the last decades probably play an essential role in decreasing VTE rates.

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