Crystalline Urea Research Articles

The electro-optic coefficients of urea

The two independent electro-optic coefficients of crystalline urea, r63 and r41, are determined experimentally using a voltage modulation technique. The results are compared with theoretical values obtained by direct summation over CNDO/S generated electronic states in a perturbation theory based expression for nonlinear optical coefficients. A further comparison is made with the predicted results of an anharmonic oscillator model for nonlinear optical processes. The results obtained by all three methods, after proper internal field corrections, agree within the limitations of the theoretical calculations and the margins of experimental error.

Utilization of seawater-urea as a culture medium for Spirulina maxima.

The possibilities of utilization of seawater enriched with ureas as the culture medium for a blue-green alga, Spirulina maxima, were investigated. Pretreatment by precipitation with NaHCO3 and (or) Na2CO3 was found essential to remove the excess amounts of Ca2+ and Mg2+ present in seawater prior to cultivation. A culture medium as good as the synthetic medium reported in the literature for the growth of S. maxima was obtained after treating seawater with NaHCO3 (19.2 g/L) at pH 9.2 and 35 degrees C for 2 h, filtering to remove precipitates, and enriching with K2HPO4 (0.5 g/L), NaNO3 (3.0 g/L), and FeSO4 (0.01 g/L). The same results were obtained by substituting a small amount (0.2 g/L or less) of either crystalline or polymerized urea for the NaNO3 in the above medium. Growth of S. maxima was inhibited at higher concentration of urea in the culture medium. The inhibition effect was due to the partial decomposition of urea into ammonia in alkali medium. Tests conducted on the 130-L cultivation open pond also confirmed that the seawater-urea medium supports growth of S. maxima as well as the best known synthetic medium.

Some Effects of Coating Urea Prills with Sulphur and Wax on Nitrogen Utilization By Ruminants

In two experiments two prilled urea products coated with sulphur and wax were given to either adult cows or sheep. In the first experiment administration per rumen fistula of the sulphur and wax-coated urea products resulted in lower concentrations of ammonia in the rumen liquor and blood of cows than did equivalent amounts of nitrogen given as crystalline feed-grade urea. Crystalline urea produced the largest and most rapid increase in the concentration of urea in the blood. In the second experiment with sheep, the addition of either of the sulphur and wax-coated urea products or crystalline feed-grade urea to a basal concentrate diet did not increase the amounts of nitrogen excreted in the faeces, indicating that each supplement was apparently fully digested. This was in contrast with the observation that some partially intact sulphur and wax-coated urea prills were present in the faeces.

An alternative method for removing low molecular weight proteins from urea and guanidine HCl solutions

Differential solubility in organic solvent mixtures provides the basis of an alternative method for removing guanidine HCl and urea from protein solutions. Solubilization and removal of these denaturing agents are accomplished by the use of specific combinations of organic solvents of varying dielectric constant, added to dehydrated mixtures of protein and crystalline guanidine HCl and urea. For the proteins tested, recovery varied directly with molecular weight.

Effect of moisture on process of diesel fuel dewaxing with crystalline urea

In the course of mastering the urea dewaxing process, the following points were established: 1. The moisture content of the suspension is the most important technological index governing the operability of the G-64 units; these units operate normally with a solid-phase moisture content of 0.7–1.5% in the adduct formation stage, 0.1% (trace) in the adduct decomposition stage, and 0.2–0.5% in the washing. 2. Moisturizing of the suspension as a result of using naphtha or feedstock with excessive water content cannot be tolerated; it leads to a gradual precipitation and sticking or lumping of the solid phase and plugging of the lines, pumps, and other equipment, and a shutdown of production. 3. The removal of moisture in an electroseparator and by settling in the regenerated-naphtha tank will serve as a reliable means for maintaining the required moisture content of the system.

N-Paraffins from kerosine cut of Mangyshlak crude

1. The C8-C15 n-paraffins required in the production of Sul'fanol detergent are present in amounts of 10–12% in 120–250 and 130–250°C cuts from Mangyshlak crude. 2. The C8-C15 n-paraffins recovered by means of crystalline urea from the kerosine cut of Mangyshlak crude, with thorough washing with a 60–80°C straight-run fraction, contain not more than 0.2% aromatic hydrocarbons, a level that is entirely satisfactory in meeting the requirements imposed on raw material for Sul'fanol production. 3. The dewaxed product meets all requirements of G'OST 10227-62 and can be used as TS-1 jet fuel.

Quality of wax obtained in urea dewaxing of diesel fuels in relation to choice of solvent

1. A study has been made of how the quality of liquid waxes obtained in diesel fuel dewaxing with crystalline urea is affected by the hydrocarbon composition of certain materials used as solvents. 2. The use of alkylate (56–172°C or 80–100°C fraction) or n-hexane will give a wax product containing less than 0.5% aromatic hydrocarbons without any supplementary treatment.

Urea dewaxing of the 230?350�C cut of Ust'-Balyk petroleum in a stationary bed of crystalline urea

1. Using a stationary bed of crystalline urea, one may obtain from the diesel distillate of Ust'-Balyk petroleum both liquid paraffins with low aromatic hydrocarbon content and winter diesel fuel components with low solidification ] points. 2. With a 1∶1 weight-to-weight ratio of urea to the feedstock, one may obtain Mark “Z” diesel fuel with minimal solidification point of −45 °C from this unpurified feedstock, but liquid paraffin with an aromatic hydrocarbon content of 0.5 wt.% or less cannot be obtained. 3. With the same ratio (1∶1), the purified feedstock enables one to obtain liquid paraffins with an aromatic hydrocarbon content of less than 0.5% and also winter diesel fuel with a solidification point of 52°C.

Electroencephalogram in ruminants. 3. Effect of experimental hyperammonemia on the REG in goats

Electroencephalograms (EEGs) were recorded bipolarly from the frontal andparietal cortical regions in 7 female goats. Silver balls (1 mm in diameter) were usedas electrodes and implanted chronically on the cerebral dura mater through a small holeof the skull. Experiments were carried out to clarify the effect of experimental hyper-ammonemia on the EEG in goats.l. When ammonium chloride (aqueous solution) was injected in an amount of0.5 milli-molecules (ml) per kg of body weight into the anterior vena cava through apolyethylene cannula, the blood ammonia concentration increased rapidly. On theEEG there appeared high-amplitude slow waves (2O0s4O0pV, 4x5 c/s) at a durationof 2 to 3 seconds and an interval of 10 to 20 seconds. This pattern was induced when theblood ammonia concentration exceeded 500pg per TOO ml of blood. There was anincrease in duration and frequerncy of appearance of this pattern with an increase indose of ammonia.2.. When ammonium chloride was infused into the anterior vena cava at a rateof 0.033 mlVI per minute per kg of body weight for 60 minutes, the blood ammoniaconcentration increased gradually, and high-amplitude slow waves tended to appear.When it was infused at a rate of 0.05 ml per minute per kg of body weight, there wasa rapid increase in this concentration and induced pattern appeared. When the bloodammonia concentration was high and the respiratory movement was in a critical state, however, low-amplitude fast waves were observed on the pattern.3. When urea was injected in a dose of 3 to 12 mM per kg of body weight intothe anterior vena cava, no induced pattern appeared at all.4. When urea was infused in a dose of 4 ml per kg of body weight irtto therumen through a permanent fistula, the induced pattern appeared.5. When crystalline urea was mixed with powdered food and fed at a rate of6 ml per kg of body weight, it was a little slower in sltowing an effect than when itsaqueous solution was infused into the rumen, there was an increase in blood ammoniaconcentration and tlae induced pat

Deparaffination of Ust'-Balyk petroleum distillate of 230?350�C range by adducting with urea

1. Optimum conditions have been determined for deparaffinating diesel distillate in the range 230–350°C from Ust'-Balyk petroleum by vigorous mechanical mixing with crystalline urea. 2. It has been found that optimum conditions for obtaining “A” grade diesel fuel are the following: an adduction temperature of 20 °C, a contact time of 30 min, a urea consumption of 100 wt. % of base material, and a total solvent consumption of 250 wt. % of base material. 3. It is shown that the amount of activator in the reaction mixture should be in proportion to the consumption of urea if the latter exceeds 100 wt. % of base material.

Electroencephalogram in ruminants. 2. Effect of experimental hyperketonemia on the electroencephalogram in goats

Electroencephalograms (EEGs) were recorded bipolarly from the frontal andparietal cortical regions in 7 female goats. Silver balls (1 mm in diameter) were usedas electrodes and implanted chronically on the cerebral dura mater through a small holeof the skull. Experiments were carried out to clarify the effect of experimental hyper-ammonemia on the EEG in goats.l. When ammonium chloride (aqueous solution) was injected in an amount of0.5 milli-molecules (ml) per kg of body weight into the anterior vena cava through apolyethylene cannula, the blood ammonia concentration increased rapidly. On theEEG there appeared high-amplitude slow waves (2O0s4O0pV, 4x5 c/s) at a durationof 2 to 3 seconds and an interval of 10 to 20 seconds. This pattern was induced when theblood ammonia concentration exceeded 500pg per TOO ml of blood. There was anincrease in duration and frequerncy of appearance of this pattern with an increase indose of ammonia.2.. When ammonium chloride was infused into the anterior vena cava at a rateof 0.033 mlVI per minute per kg of body weight for 60 minutes, the blood ammoniaconcentration increased gradually, and high-amplitude slow waves tended to appear.When it was infused at a rate of 0.05 ml per minute per kg of body weight, there wasa rapid increase in this concentration and induced pattern appeared. When the bloodammonia concentration was high and the respiratory movement was in a critical state, however, low-amplitude fast waves were observed on the pattern.3. When urea was injected in a dose of 3 to 12 mM per kg of body weight intothe anterior vena cava, no induced pattern appeared at all.4. When urea was infused in a dose of 4 ml per kg of body weight irtto therumen through a permanent fistula, the induced pattern appeared.5. When crystalline urea was mixed with powdered food and fed at a rate of6 ml per kg of body weight, it was a little slower in sltowing an effect than when itsaqueous solution was infused into the rumen, there was an increase in blood ammoniaconcentration and tlae induced pat

Gamma radiolysis of crystalline urea

Products formed by the γ-radiolysis of crystalline urea are, in order of decreasing G value, H 2NCHO, H 2, H 2NCONHCONH 2, N 2, NH 3, H 2NCONHNHCONH 2, H 2NCONHNH 2 and H 2NCOCONH 2; G(-urea) = 0·53. The yields appear to be independent of the presence of oxygen and of absorbed dose. Energy dissipation and radical caging are believed to be facilitated by the highly hydrogen-bonded structure of the crystals and to account for relatively low G(product) values. Product yields and the mass spectrum of urea suggest that radiation causes predominantly CN bond fission; a radiolysis mechanism is proposed. Radiolysis of the 1-iodohexane-urea inclusion compound gives a greater yield of iodine than radiolysis of pure 1-iodohexane. For the inclusion compound, G(I 2) is independent of absorbed dose.

The effect of urea on the utilization of ground, pelleted roughage by penned sheep: I. Food intake, live-weight change and wool growth

SUMMARYIndividually-penned adult Merino wethers were fed for 16 weeks on a basal diet of ground, pelleted oat straw orPhalaris straw. Urea was supplied either in a salt-urea block containing 30% urea, or as crystalline urea incorporated into the pellets. A commercial mineral supplement was given during the first 8 weeks, but this was replaced with a laboratory-prepared mineral mix during the second 8 weeks.Urea supplementation significantly reduced live-weight loss. Over the 16 weeks control sheep lost a mean of 14·5 kg, and supplemented sheep 8·7 kg body weight. Most of this response to urea occurred during the second half of the experimental period.Food intakes of all sheep increased over the first 2 weeks and then fell. In the unsupplemented groups, levels of intake then remained fairly low, whereas in the sheep fed urea food intakes rose over the final 6 weeks of the experiment. There was a significant linear regression of live-weight change on food intake only with the urea-fed sheep. Intakes of urea-N from the blocks were extremely variable between individual sheep and between periods within sheep; in most cases, however, they appeared to be adequate, as this type of supplementation gave results similar to those obtained by mixing urea throughout the roughage.There was no significant effect of urea on total wool growth during the experimental period, although wool growth in the supplemented shepp showed a rise towards the end of the experiment. Wool growth in any 4-weekly period was closely related to food intake and live-weight change during that period.

RADIOCARBON-LABELED COMPOUNDS PRODUCED BY THE NEUTRON IRRADIATION OF CRYSTALLINE UREA AND ACETAMIDE HYDROCHLORIDE1

The nature and relative quantities of the radiocarbonlabeled compounds resulting from the pile-neutron irradiation of crystalline urea and acetamidine hydrochloride were investigated. Biuret and urea were found to contain 27 and 22%, respectively, of the total carbon-14 activity induced in the urea sample by neutron irradiation. The parent molecule, acetamidine, was found to contain 12% of the total carbon-14 activity induced in the acetamidine hydrochloride sample. In both studies, little activity was found in the form of simple compounds. Possible reaction mechanisms are suggested for the formation of the compounds containing appreciable percentages of the total activity. (auth)

Urea inclusion compounds of n-alkyl oxiranes and n-mercaptans

The effect of a 1,2-epoxy group in a normal alkane on the urea inclusion compound forming ability of a molecule is negligible and consistent with the cross-sectional diameter of the molecule. 1,2-Epoxyoctane is the shortest homologue that formed an inclusion compound. X-ray powder diffraction patterns were used to verify the formation of the inclusion compounds and to determine their relative stability. Crystalline urea inclusion compounds of n-alkyl mercaptans were prepared. The formation of the complex was verified and relative stability determined from the X-ray powder diffraction data. The odour of the mercaptan guest in the urea host was never removed although diminished. None of the branched mercaptans tested formed a urea inlclusion. n-Amyl mercaptan was the shortest homologue which formed a complex and n-decyl was the longest normal mercaptan tested.

Influence of Biuret and Urea Fertilizers Containing Biuret on Corn Plant Growth and Development1

SynopsisBiuret was toxic to germinating seeds and caused injury to developing corn seedlings. Hyponasty, frayed leaf margins, and interveinal leaf chlorosis in immature leaves were symptoms associated with this injury. Crystalline urea did not cause this injury to developing corn seedlings. Placement away from seed minimized the probability of biuret injury.

The value of calcium nitrate and urea for main-crop potatoes and kale

1. Twenty-two experiments on main-crop potatoes in 1955–7 compared calcium nitrate and ammonium sulphate applied to the seedbeds before planting. Urea was also tested in fifteen of the experiments in 1956–7. The three fertilizers were compared at rates that supplied 0·5, 1·Oand 1·5 cwt. N/acre.2. Seven experiments on kale in 1955–8 compared seedbed dressings of calcium nitrate and ammonium sulphate. Urea “was also tested in. five of the experiments in 1956–8. The rates used were 0·6, 1·2 and 1·8 cwt. N/acre in 1955 and 1·0 and 2·0 cwt. N/acre subsequently. Single dressings applied to the seedbed were also compared with divided dressings applied partly to the seedbed and partly in mid-season.3. Generally the potatoes gave only small responses to N; there was no worthwhile gain from applying more than 1·0 cwt. N/acre in 1955 and 0·5 cwt. N in 1956 and 1957. Nitrogen gave much larger proportionate increases in yields of kale, at several of the centres crops continued to respond up to dressings of 2·0 cwt. N/acre.4. Calcium nitrate generally gave lower yields of potatoes than ammonium sulphate and the superiority of ammonium sulphate was greater with the higher dressings. Losses in yield with the nitrate were usually associated with a severe check to early growth occurring in dry springs and with dressings concentrated close to the seed, but lower yields were also obtained at some centres where early growth was not damaged. Calcium nitrate and ammonium sulphate were roughly equivalent for kale when the nitrate did not damage germination; heavy seedbed dressings of the nitrate reduced kale plant numbers severely unless there was adequate rain after sowing.5. Granulated urea tested in 1956 contained 4·5% of biuret, it delayed emergence and reduced plant establishment seriously in several of the potato experiments; damage increased with the level of manuring and was accentuated when dressings were broadcast over furrows before hand-planting. Yields given by this batch of urea were less than with other N fertilizers and when 1·5 cwt. N/acre was applied they were less than with no nitrogen at all. Purer crystalline urea (having less than 1% of biuret) used in the 1957 experiments caused no damage to emergence of potatoes and gave yields similar to those obtained with ammonium sulphate. There were similar effects in the kale experiments; granulated urea containing much biuret damaged germination severely in 1956; the purer products containing little biuret used in later years reduced plant numbers at one centre in 1957 and at the single 1958 centre. Where there was no damage to the establishment of kale, urea and ammonium sulphate gave similar yields.6. Dressings applied partly to the seedbed and partly in mid-season gave slightly higher average yields of kale than an equivalent total amount of nitrogen all applied before sowing.

Urea as an Extender of Protein When Fed to Lambs

Cottonseed meal, crystalline urea, DuPont's “Two-Sixty-Two” feed compound and pelleted concentrate feeds containing approximately 4, 8 and 12 percent of urea were fed as sources of supplemental nitrogen for lambs during digestion and nitrogen balance trials. The addition of urea alone and as "TwO-Sixty-Two" to a basal ration of low-protein prairie hay increased the apparent digestibility of hay nutrients and changed nitrogen balances from slightly negative values to slightly positive values. Pelleted feeds with 25 percent of their total nitrogen supplied by 4 percent of urea permitted about the same storage of nitrogen as cottonseed meal. Nitrogen storage decreased as the proportion of total nitrogen supplied by urea was increased in the pellets to 50 and 75 percent.

NITROGEN AND SULPHUR METABOLISM IN BRIGHT'S DISEASE

Patients suffering from chronic nephritis with renal edema tend to retain both nitrogen and sulphur when fed diets high in protein,1and even retain crystalline urea.2On the other hand, it has been shown that patients with Bright's disease without renal edema tend toward a negative sulphur and nitrogen balance as the disease progresses.3The mechanism of these reactions is not clear, as it has been impossible to demonstrate an elevation of the nonprotein nitrogen level of the blood in patients retaining large quantities, whereas in patients without renal edema the nonprotein nitrogen level of the blood rises despite the negative balance. In the study of patients with renal edema it can be shown by a simple calculation that if the retained nitrogen and sulphur or urea is equally distributed throughout the body, easily measurable quantities should be demonstrable in the blood. It has always been assumed

NITROGEN AND SULPHUR METABOLISM IN BRIGHT'S DISEASE

It has previously been noted by Peters and others1that patients exhibiting the nephrosis syndrome retain a large proportion of the intake of nitrogen without an increase in the nonprotein nitrogen in the blood, and that even when crystalline urea is added to the diet, it is retained. Peters and Van Slyke2thought that the retention of nitrogen serves to make up the loss of body protein chiefly in the form of albumin excreted in the urine. If this is true, it accounts in part for the retention of sulphur noted formerly.3So far as I have been able to ascertain, no studies have been made on the relation between the excretion of nitrogen and that of sulphur in this condition when crystalline urea has been added to a diet already high in protein. I shall report metabolism studies on a patient, whose case history was included