Isometric Forms Research Articles

Improvement of the process of improving the quality of urea granules

The object of research is the process of improving the quality of urea granules by processing. The subject of research is the physicochemical properties of granular urea after processing with a new composite. Granular urea has a wide range of uses, but during storage and sale it is capable of caking with a significant loss of its flowability, static and dynamic strength of granules. When transporting over long distances, these phenomena cause inconvenience in loading and unloading operations, and also affect the quality of the supplied goods. Therefore, the search for methods to improve its quality is still important. The paper considers the results of theoretical studies of ways to improve the quality of granular urea. As a rule, at most enterprises, an additive is introduced into the urea melt - urea-formaldehyde concentrate, which promotes the formation of isometric forms of urea crystals and reduces the growth rate of faces with the third pinacoid. Due to the toxicity of formaldehyde, the market for such urea is limited. The results are presented for laboratory tests of the processing of urea produced by pouring without a fluidized bed, a new anti-caking composite – a hydrolyzed solution of protein raw materials from the family of fibrillar proteins with a protein raw material concentration of 10 %. The main purpose of the granule processing was to improve the quality of urea through the use of a new composite anti-caking agent, which leads to an increase in the shelf life without changing the physicochemical properties and provides an environmentally friendly condition. As a result of laboratory studies, a decrease in moisture absorption was revealed. It has been established that the proposed anti-caking agent exhibits a hydrophobilization effect. The effectiveness of the conditioning action of the proposed composite has been proven, which consists in achieving fixation of a hydrophobic coating of natural origin on the surface of fertilizer granules and, as a consequence, reducing the percentage of caking of fertilizers. The disadvantages of the developed composite were also established, namely: the fact of a decrease in the static strength of granules after processing was established. Therefore, work on improving the composition of the composite will continue.

ОПРЕДЕЛЕНИЕ ЦЕЛЕСООБРАЗНОСТИ ГРАВИТАЦИОННОГО ОБОГАЩЕНИЯ РУДЫ МЕСТОРОЖДЕНИЯ «ДЖАМГЫР»

PURPOSE. The paper studies the material composition of the ore from the Jamgyr deposit located in the Chatkal region of the Jalal-Abad district of the Kyrgyz Republic and determines the expediency of its gravity concentration. The ore belongs to the quartz low sulfide type. Its main valuable component is gold, the content of which averages 8.5 g/t. METHODS. Complex mineralogical analysis was performed using X-ray phase, optical and microscopic analyzes. Sulphide minerals and gold were studied using the method of selective dissolution of natural minerals. X-ray phase analysis was carried out on a portable X-ray diffractometer D2 PHASER (CuKa) of Bruker AXS design in the range of 20 angles from 5 to 80°. The obtained diffractograms were processed in the DIFFRAC.EVA program. A qualitative X-ray phase analysis was performed via comparison of standards (ICDD PDF-2) and diffractograms. A semiquantitative analysis of the sample was carried out using the DIFFRAC.TOPAS program according to Rietveld method. The content of gold was determined on the atomic absorption multielement spectrometer AGEP-0,1 by the assay atomic absorption analysis. RESULTS AND THEIR DISCUSSION. Having studied the morphology of particles of free gold, we have found that the shape of coarse gold is mainly dendritic, small-size gold has the shape of a drop in pyrite. The data on the granulometric distribution of gold show that the percentage of coarse gold is about 70%. The phase analysis data show that the percentage of free gold is 64.37%. The ore study has allowed to substantiate the use of gravity concentration through the GRG test at a hydraulic pressure of 25-12 kPa, ore feed rates from 1000 g/min to 400 g/min, stage-by-stage reduction in size from 100% of 85 μm to 80% of 75 μm. The technique of performing the stage-by-stage gravity concentration conducted in three stages on Knelson concentrator is given and the GRG test determination diagram is presented. The results of each stage and the total result of the GRG test are provided. According to the GRG test result 19.86% of free gold is extracted at the first stage, 35.83% - at the second stage, and 17.65% - at the third stage. The total recovery is 73.34%. CONCLUSIONS. The morphology and release of gold on the concentrates obtained by gravitation on a centrifugal separator are studied. The degree of gold release is determined as well as the gold grain size in I, II, III stage concentrates and relative amounts of free gold grains. The final determination is given to the main shape of gold grains: it is either dendritic or flake. It is also noted that stage-by-stage decrease in the grind size causes changes in the gold grain shape: the particles of isometric forms are expanded into flat grains.

Consistency of surface electromyography assessment at lower limb selected muscles during vertical countermovement.

Given the difficulty of invasive methods to assess muscle action during natural human movement, surface electromyography (sEMG) has been increasingly used to capture muscle activity in relation to kinesiological analysis of specific tasks. Isolated isometric, concentric and eccentric forms of muscle action have been receiving the most attention for research purposes. Nevertheless natural muscle action frequently involves the use of a preceding eccentric muscle action as a form of potentiation of immediate muscle concentric action, in what is designated as muscle stretch-shortening cycle (SSC). The most frequently applied protocols for the evaluation of SSC on vertical jumps are by virtue of their reproducibility and control of experimental conditions, squat jump (SJ) without countermovement (CM), countermovement jump (CMJ) with long CM and drop jump (DJ) with short CM. The methods used to extract information and relationship of the captured signals also present a high diversity, with the question about the consistency of the methods and obtained results. The objective of this study is to evaluate the consistency of the analysis and results by applying different EMGs signal analysis techniques related to strategic muscle groups of the lower limbs at different countermovement evaluated in vertical jumps. Raw sEMG signals of 5 lower limb muscles of 6 subjects during SJ, CMJ and DJ were rectified, filtered and obtained their envelope, and then correlated (CR) for detection of synergistic, agonist and antagonist activity, applied principal component analysis (PCA) for the detection of uncorrelated components explaining maximum variability and normalized cross-correlation (CCRN) for detection of maximum correlations and time lag. CR of EMG envelopes presented higher coactivities (CoA) in DJ relative to SJ and these CoA superior to CMJ with greater synergy in DJ relative to SJ and CMJ that present several loop cycles corresponding to time lag of activity. CCRN of the EMG envelopes presented also higher CoA in DJ when compared to SJ and both higher CoA to CMJ. PCA allowed to detect a principal component (PC) explaining 92.2% of the variability of EMG in DJ, 90.6% in SJ and 78.7% in CMJ, the second PC responsible for the explanation of 4.9% variability in DJ, 6.7% in SJ and 15.3% in CMJ.

Detecting repetitions and time features in resistance training using triaxial accelerometry

Accurately determining resistance-training parameters is crucial to gain knowledge about the training process and to evaluate training interventions. To current knowledge, no method exists to automatically detect a series of features in a repetition training session using one three-dimensional accelerometer. In this study, a specific algorithm was used to detect the number of repetitions and different time features. Features determined by the acceleration algorithm were compared to a reference system using a linear wire encoder to detect movements. A total of 50 healthy participants were randomly assigned to three different groups (maximal strength, hypertrophy, and muscular endurance) and executed three different resistance-training exercises (bench press, leg press, and trunk flexion). Results of both measurement systems were compared for agreement using Bland–Altman plots, regarding repetition numbers, TUT (time under tension) in concentric, eccentric, and isometric contraction forms and total TUT (sum...

An elementary proof that rationally isometric quadratic forms are isometric

Let R be a valuation ring with fraction field K and 2 ∈ R ×. We give an elementary proof of the following known result: two unimodular quadratic forms over R are isometric over K if and only if they are isometric over R. Our proof does not use cancelation of quadratic forms and yields an explicit algorithm to construct an isometry over R from a given isometry over K. The statement actually holds for hermitian forms over valuated involutary division rings, provided mild assumptions.

Classifying quantum phases using matrix product states and projected entangled pair states

We give a classification of gapped quantum phases of one-dimensional systems in the framework of Matrix Product States (MPS) and their associated parent Hamiltonians, for systems with unique as well as degenerate ground states, and both in the absence and presence of symmetries. We find that without symmetries, all systems are in the same phase, up to accidental ground state degeneracies. If symmetries are imposed, phases without symmetry breaking (i.e., with unique ground states) are classified by the cohomology classes of the symmetry group, this is, the equivalence classes of its projective representations, a result first derived in [X. Chen, Z.-C. Gu, and X.-G. Wen, Phys. Rev. B 83, 035107 (2011); arXiv:1008.3745]. For phases with symmetry breaking (i.e., degenerate ground states), we find that the symmetry consists of two parts, one of which acts by permuting the ground states, while the other acts on individual ground states, and phases are labelled by both the permutation action of the former and the cohomology class of the latter. Using Projected Entangled Pair States (PEPS), we subsequently extend our framework to the classification of two-dimensional phases in the neighborhood of a number of important cases, in particular systems with unique ground states, degenerate ground states with a local order parameter, and topological order. We also show that in two dimensions, imposing symmetries does not constrain the phase diagram in the same way it does in one dimension. As a central tool, we introduce the isometric form, a normal form for MPS and PEPS which is a renormalization fixed point. Transforming a state to its isometric form does not change the phase, and thus, we can focus on to the classification of isometric forms.

Morphological analysis of viral communities in the floodwater of a Japanese paddy field

Capsid size distributions of viral communities in the floodwater of a Japanese paddy field under a long-term fertilizer trial were surveyed during the rice cultivation period by using transmission electron microscopy. The capsid size distributions were monophasic, and the median values fell within the range of 50–70 nm. The quartile intervals were narrow from either 40–50 nm or 50–60 nm to either 60–70 nm or 70–80 nm for most samples. There was no clear seasonal variation in the capsid size distribution of viral communities. The difference in size distributions among different fertilizer plots was also not found. Viral communities in the floodwater were predominated by isometric icosahedral forms. Viruses with octahedral capsids and elongated ones were rare and sporadic in the floodwater.

Investigation of ferrites properties with polyaniline layer in anticorrosive coatings

The presented paper is devoted to pigments of various chemical compositions and particles morphology surface-modified by polyaniline layer as corrosion inhibitors to coatings. They were synthetized of pigments on the spinel base, ferrites with contents of Zn, Mg and Ca cations with isometric and nonisometric forms of primary particles. These pigments were surface-modified with electrically conductive polymer, polyaniline, by the oxidative polymerization of aniline. The surface composition of coated pigments was characterized by Fourier transform infrared (FTIR) spectrum and scanning electron microscopy (SEM). For testing the properties of pigments prepared, the model coatings compositions were formulated using solvent-based alkyd resin. On the tested samples, corrosive tests were performed. The present research has shown that the presence of polyaniline has better efficiency in protection against corrosion than spinel-type pigments alone in the selected alkyd resin.

Binding at molecule/gold transport interfaces. V. Comparison of different metals and molecular bridges

The geometric and electronic structural properties of symmetric and asymmetric metal cluster-molecule-cluster' complexes have been explored. The metals include Au, Ag, Pd, and Al, and both benzenedithiol and the three isometric forms of dicyanobenzene are included as bridging molecules. Calculated properties such as cluster-molecule interface geometry, electronic state, degree of metal --> molecule charge transfer, metal-molecule mixing in the highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) energy region, the HOMO-LUMO gap, cluster --> cluster' charge transfer as a function of external field strength and direction, and the form of the potential profile across such complexes have been examined. Attempts are made to correlate charge transport with the characteristics of the cluster-complex systems. Indications of rectification in complexes that are asymmetric in the molecule, clusters, and molecule-cluster interfaces are discussed. The results obtained here are only suggestive because of the limitations of the cluster-complex model as it relates to charge transport.

Nodular Fraction of Phosphatic Sand from the Namibia Shelf

Morphology, microstructure, and chemical composition of the nodular fraction of phosphatic sand from the outer Namibia shelf are considered. The nodules are divided into three varieties: concretions, phosphatic casts of shells pelecipod and gastropod, and phosphatized sea lion coprolites. A part of nodules shows massive homogeneous structure, whereas other nodules contain sand-size phosphatic grains derived from the host phosphatic sand. All nodules display the same spectrum of microstructures, including colloform, granular-globular, and crystallomorphic ones. The crystallomorphic nodules are composed of scattered and aggregated crystallites of isometric, rod-shaped, and dumbbell-shaped forms, as well as crystallized shells on grains incorporated into nodules. Phosphatized remains of diatoms, foraminifers, and embryonic gastropods, as well as vermicular and filamentous bacterial forms occur among biogenic components of the nodules. Framboidal pyrite is present in all nodules. In terms of phosphate microstructure, character of organic remains, and chemical composition, the nodules are similar to phosphate grains of the host sand, recent phosphorites from the inner Namibia shelf, and some ancient phosphorites.

Rationally but not integrally isometric bilinear forms

Let K be a non-dyadic local field and A its ring of integers. First we notice that the classification of unimodular A-bilinear forms and of systems of two unimodular symmetric A-bilinear forms are both reduced to the classification of hermitian forms over the category of double isomorphisms over projective A-modules ; the duality is nevertheless different for each case. Then we use the methods of reduction and transfer to construct some examples of non isometric unimodular forms (or system of unimodular symmetric forms) having the same asymmetry and becoming isometric over K.

Unit-Cell Models of Isometric Crystals

All crystal shapes can be built up from unit cells. Illustrations of unit cells used to build a few simple forms are widely reproduced, but most crystal forms seem to have been rarely if ever illustrated this way. With modern computer graphics technology it is quite easy to build models of any desired crystal form. Unit cell models of important isometric forms and their construction are described here.

Molecular Characterization of the DNA of Anatid Herpesvirus 1

A plaque-purified isolate of the Holland strain of Anatid herpesvirus (AHV-ppc3) was purified by differential and buoyant density sedimentation. The virus buoyant density was 1.215 g/cm3 in sucrose. AHV-ppc3 DNA was analyzed by sedimentation velocity studies in neutral or alkaline sucrose gradients. Based upon a comparison with T4 DNA, the DNA of AHV-ppc3 was found to have a sedimentation coefficient of 59.7 S and a molecular mass of 1.19 x 10(8) daltons. Between 15 and 22 bands were observed in agarose gel electrophoresis with AHV DNA cut by BamHI, EcoRI, PstI or BglII. The possibility of isometric forms is indicated by the finding of restriction fragments having molar ratios differing from 1.0. The mean molecular mass calculated from the fragments was 1.18 x 10(8) daltons. Terminal fragments were identified using exonuclease II and BgII. In alkaline sucrose gradients, AHV DNA fragments with the largest of the most abundant species have a sedimentation coefficient of 69 S and a calculated mass of 6.0 x 10(7) daltons. The buoyant density of AHV-ppc3 DNA in cesium chloride was 1.723 g/cm3 corresponding to a % G + C content of 64.3. This finding was supported by thermal melts of the DNA in SSC/10 in which the thermal melting point was 82.7 degrees. The data support a model for AHV in which the viral duplex DNA is linear, without covalently closed termini or significant base modifications, but with single strand nicks or gaps. The % G + C content of AHV DNA is the highest reported for any avian herpesvirus in the alpha-herpesvirinea subgroup.

Polyatomic ions: Bond energies, most stable isometric form and low excited states

Bond energies are quite accurately additive in saturated polyatomic ions notwithstanding the long-range interactions and the marked dependence on the complexity of the ion of the extent of the dispersal of the free charge. Additivity is a less good approximation for unsaturated polyatomic ions. However, patterns emerge that allow predictions on association energies to be made and facilitate the identification of the most stable of the several isometric forms. The two most stable isometric forms are commonly not far apart in the energy.

Inhibitory potential of acetaminophen and o-, m-, p-aminophenols for development of γ-glutamyltranspeptidase-positive liver cell foci in rats pretreated with diethylnitrosamine

The inhibitory potential of treatment with acetaminophen (AAP) and 3 different isometric forms of monoaminophenols ( o-, m-, p-AP) for the development of γ-glutamyltranspeptidase-positive (γ-GT +) liver cell foci was examined in an in vivo short-term assay system. Rats were initially given a single intraperitoneal injection of diethylnitrosamine (DEN) and fed test compounds from week 2 until they were killed at week 6, all rats being subjected to two-thirds partial hepatectomy at week 3. All 4 compounds exerted obvious inhibition of the development of γ-GT foci with both number and area (mm 2) being reduced. AAP proved the most potent agent whereas dose-related inhibitory potential was observed within the 2 doses of p-AP treated.

Tetraborane(8) adducts of strongly basic phosphines

Abstract : Four methods were developed for the preparation of B4H8.P(CH3)3. the removal of one of thhe trimethylphosphine ligands from B4H8.2P(CH3)3 by B2H6, the hydride removal from B4H9P(CCH3)3byB2H6, the boron framework expansion of B3H7THF with the use of B2H42P(CH3)3 and the reaction of B3H62P(CH3)3B3H8- with trimethylamine. The yields were better than 90%. The adduct of tris(dimethylamino)phosphine, B4H8.P(N(CH3)2)3 was prepared from the above mono(phoshine)adducts. These were B4H8P(N(CH3)3N(CH3)3N(CH3)3, and B4H8P(CH3) 3P(N(CH3)2)3. The former existed in two isometric forms, each being different from the other in the positions of the two different ligands. These compounds were characterized by their 11B1H, and 31P NMR spectra. Originator-supplied keywords include: Boranes, Phoshines, Lewis Bases.

Mineralogy and Acidity of an Inland Acid Sulfate Soil of Texas

AbstractThe Aubrey soil occurs in the East Cross Timbers Region of north‐central Texas. It has developed in an acid clayey shale of the Lewisville member of the Woodbine geologic formation of Upper Cretaceous age. Jarosite [KFe3(OH)6(SO4)2] occurs in localized concentrations in the lower horizons. Selected particles form the C horizon were 87.6% jarosite and served as a reference mineral for the soil. Jarosite content of the B3 and C horizons was 1.6 to 6.7% and was detectable by thermal and x‐ray diffraction analyses of the whole soil. Scanning electron microscope examination indicated that the jarosite occurred as cubes and octahedra. These isometric forms suggest jarosite formation from pyrite present in the parent material. Smectite and kaolinite are the major clay constituents and they are both more poorly crystalline in the major A and B horizons than in the lower three horizons. The pH in water ranges from 5.0 in the upper B horizon at the 8‐cm depth to 4.0 in the C horizon to the 152‐cm depth. Exchangeable and nonexchangeable acidity increase with depth into the C horizon. The Aubrey soil has developed an accumulation of free Fe oxides above the jarosite zone, which is characteristic of an acid sulfate soil.

The effect of a combination of timolol, hydrochlorothiazide and amiloride on 24 hour blood pressure control using ambulatory intra‐ arterial monitoring.

1 The effectiveness of fixed combination tablets of timolol 10 mg, hydrochlorothiazide 25 mg and amiloride 2.5 mg (Moducren) once daily in the control of blood pressure has been assessed in fully ambulant hypertensives by the technique of continuous intra-arterial recording. Highly significant blood pressure reduction (P less than 0.001) was obtained consistently throughout the whole day, confirming the potency and usefulness of the preparation for those patients who need more than one drug to control their blood pressure. 2 Blood pressure responses to both isometric and dynamic forms of exercise were also significantly lowered by combination therapy. 3 The addition of a diuretic to a beta-adrenoceptor blocker appears to be an advantage if the aim of treatment in hypertension is 24 h blood pressure control.

The use of a laboratory data processor for the presentation of surface scanning data

A small laboratory data processor has been used to simplify presentation of information from surface scanning studies. Display options include number pattern, isometric and multi-colour contour forms.

Chemistry of oxo-metal ions-VI 1,10-phenanthrolinium oxopentachloromolybdate(V) and its derivatives

1,10 Phenanthrolinium oxopentachloro molybdate(V), PhenH 2[MoOCl 5] has been isolated as yellowish-green solid and from this salt the non-electrolytic paramagnetic complexes MoOCl 3·phen have been prepared in three different isometric (colored reddish-pink, pale brown and green) forms by dehydrohalogenation in suitable solvent and solid state reaction. Hydrolysis of the parent salt yielded the diamagnetic complex, Mo 2O 4Cl 2(phen) 2 as brownish red solid. All these products and the parent salt have been shown to be interconvertible and the probable constitution of expected cis-trans isomers of MoOCl 3·phen has also been discussed. All these compounds have been studied by various physicochemical methods and it has been shown that the oxometal entity MoO 3+ remains intact under various chemical environments.