Salinity separation

Chromosomes are made of two chromatids held together by a centromere, which may be in the middle (epicentric), at one end (acrocentric), or between the midline and the end (metacentric) of the chromosome. The chromatids, which adhere to each other before treatment with saline, separate except for contact in the area occupied by the centromere. Consequently, after hypotonic treatment, epicentric chromosomes look like X s, acrocentric chromosomes like V s, and all other chromosome like Y s. The length of the stem of the Y depends upon the position of the centromere between the midline and the end of the chromosome. 

The seminal discovery that transformed membrane separation from a laboratory to an industrial process was the development, in the early 1960s, of the Loeb-Sourirajan process for making defect-free, high flux, asymmetric reverse osmosis membranes (5). These membranes consist of an ultrathin, selective surface film on a microporous support, which provides the mechanical strength. The flux of the first Loeb-Sourirajan reverse osmosis membrane was 10 times higher than that of any membrane then avaUable and made reverse osmosis practical. The work of Loeb and Sourirajan, and the timely infusion of large sums of research doUars from the U.S. Department of Interior, Office of Saline Water (OSW), resulted in the commercialization of reverse osmosis (qv) and was a primary factor in the development of ultrafiltration (qv) and microfiltration. The development of electro dialysis was also aided by OSW funding. 

Tannins occur in many plants and are separated by extraction. At present, only quebracho extract is used as a mud thinner in significant quantity in the United States. Quebracho is an acidic material and performs best at high pH. It is an excellent thinner for lime-treated and cement-contaminated muds. However, it is not effective at high salt concentrations. Sulfomethylated tannin products are functional over a wide range of pH and salinity and have either been treated with chromium for good thermal stabiUty (58) or are chrome free. Concentrations of tannin additives are ca 1.5—18 kg/m (0.5—6 lb/bbl). 

Minimal Energy Requirements. The relative effect of the cost of the energy on the cost of the freshwater produced depends on local conditions, and is up to one-half of the total. In attempting to reduce this cost, it is of interest to determine the minimal energy amount thermodynamically needed for separating the water from the saline solution. The physical background to this will be introduced in a simple example. Because of the negligible... 

The ice crystals must be separated from the saline solution surrounding them, and washed with freshwater. This is accompHshed by a downward countercurrent flow of a small amount of freshwater through the ice slurry in the washer—melter unit. Keeping that unit at about 0°C limits the needed pressure rise by the compressor to only about 130—260 Pa, and an auxiUary refrigerator is often used to compensate for heat gains from the ambient and the compression. 

Electrodialysis. In electro dialysis (ED), the saline solution is placed between two membranes, one permeable to cations only and the other to anions only. A direct electrical current is passed across this system by means of two electrodes, causiag the cations ia the saline solution to move toward the cathode, and the anions to the anode. As shown ia Figure 15, the anions can only leave one compartment ia their travel to the anode, because a membrane separating them from the anode is permeable to them. Cations are both excluded from one compartment and concentrated ia the compartment toward the cathode. This reduces the salt concentration ia some compartments, and iacreases it ia others. Tens to hundreds of such compartments are stacked together ia practical ED plants, lea ding to the creation of alternating compartments of fresh and salt-concentrated water. ED is a continuous-flow process, where saline feed is continuously fed iato all compartments and the product water and concentrated brine flow out of alternate compartments. 

The voltage used for electro dialysis is about 1 V per membrane pair, and the current flux is of the order of 100 A/m of membrane surface. The total power requirement increases with the feedwater salt concentration, amounting to about 10 MW per m product water per 1000 ppm reduction in salinity. About half this power is required for separation and half for pumping. Many plant flow arrangements exist, and their description can be found, along with other details about the process, in References 68 and 69. Many ED plants, as large as 15,000 vsf jd, are in operation, reducing brackish water concentration typically by a factor of 3—4. 

Follicle Stimulating Hormone (FSH, foilitropin) [9002-68-0] Mr 36,000. Purified by Sephadex GlOO gel filtration followed by carboxymethyl-cellulose with NH4OAC pH 5.5. The latter separates luteinising hormone from FSH. Solubility in H2O is 0.5%. It has an isoelectric point of 4.5. A soln of Img in saline (lOOmL) can be kept at 60° for 0.5h. Activity is retained in a soln at pH 7-8 for 0.5h at 75°. The activity of a 50% aq EtOH soln is destroyed at 60° in 15 min. [Bloomfield et al. Biochim Biophys Acta 533 371 1978 Hartree Biochem J100 754 1966 Pierce and Parsons Ann Rev Biochem 50 465 1981.]... 

Calf kidneys, dog kidneys and rhesus monkey kidneys were treated with trypsin to give suspensions of cells. The suspensions were centrifuged and the packed cells diluted with 400 volumes (calf cells) or 200 volumes (dog cells and rhesus monkey cells) of a growth medium consisting of 5% horse serum and 0.5% lactalbumen hydrolysate in Earle s saline, with 100 units/ml each of penicillin and streptomycin. These media were used separately to produce Semliki Forest/calf interferon, Semliki Forest/dog interferon and Semliki Forest/rhesus monkey interferon. The cell-containing growth medium was dispensed into 500 ml medical flat bottles (70 ml in each). The cultures were incubated at 36°C. Confluent sheets of cells (monolayers) were formed in 5 to 6 days. The growth medium was then removed and the monolayers were washed with isotonic phosphate-buffered saline, pH 7.5. 

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

The second valve controls a sample loop, 5 cm long and 1 mm in diameter, packed with dimethyloctadecyl reverse phase comprising of fairly coarse particles 100-120 im in diameter to reduce flow impedance. The sample pump is supplied via a two-way tap from either of two reservoirs, one containing pure water and the other, normal saline. The output of the pump can be used to either force the contents of the open loop sample tube through the packed loop, or to permit washing with an appropriate solvent. The separate pump is necessary to overcome the impedance of the packed loop. 

Organophosphates, such as methyl parathion, are known to inhibit cholinesterase activity. A method has been developed to measure the extent of this inhibition and relate it to organophosphate exposure (EPA 1980d Nabb and Whitfield 1967). In this EPA-recommended method, blood is separated into plasma and red blood cell fractions. The fractions are treated with saline solution, brought to pH 8 with sodium hydroxide, and dosed with acetylcholine perchlorate. The ensuing acetic acid releasing enzyme reaction... 

Separation. The proeess by which the bacterial cells are separated from the culture fluid. Centrifugation using either a batch or continuous flow process is commonly used, but preeipitation of the cells by reducing the pH is an alternative. In the case of vaeeines prepared fiom eells, the fluid is discarded and the cells are resuspended in a saline mixture where vaeeines are made fiom a constituent of the fluid, the cells are discarded. 

Typhoidt whole cell Cultures of Sat. typhi grown in liquid media 1 Killing with heat or phenol 2 Separation and resuspension of bacteria in saline Induction of antibodies in rabbits Exclusion of live Sai. typhi... 

Some effort has been directed toward understanding the growth requirements of the alga of interest, allelopathic alga (13), the optimum salinity (14), the distribution of allelopathic agents (15), and the temperature optimum (16). This paper reviews the approaches taken to separate the allelopathic agents from the other materials and the methods used to characterize the biological activity of aponin from Nannochloris sp. 

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