Calorimetric Investigation of Grafting of Styrene and Methylmethacrylate onto Air-Preirradiated Polyethylene

All existing and widely used methods for measuring reaction rate of polymerization processes suffer from basic disadvantages including indirect measurement, insufficient accuracy and limited applicability. Their unsuitability is especially pronounced in the investigation of graft copolymerization reactions in which the accuracy of measurement could be affected even by the different properties of individual polymer samples. In this work a new method, calorimetry, free of mentioned disadvantages is generally proposed for investigation of polymerization processes and particularly its application to radiation induced grafting of styrene and methylmethacrylate onto polyethylene is demonstrated. Experimental results showed the possibility of calorimetry to measure the grafting rate continuously and directly in the whole conversion range with the accuracy much better than with any other method used so far. It was concluded that styrene grafting is non-diffusion-controlled, whereas methylmethacrylate grafting is not diffusion- independent. With both monomers the reaction kinetics was found to be dependent on the type of polyethylene a s a consequence of different mechanisms, i. e. in the initiation step two different species, peroxy radicals and peroxides, take part. Its concentration is different in two types of polyethylene used. In the case of high density polyethylene both active species participate in the initiation process equally, according to their different nature. However, in low density polyethylene the concentration of peroxy radicals is negligible compared to that of peroxides and therefore peroxides have dominating role in the initiation step of grafting reaction. The change of the viscosity of reaction medium in the course of reaction as well as the structure of polymer in the case of high density polyethylene influence the kinetics of grafting reaction

The micropropagation of chrysanthemums via axillary shoot proliferation and highly efficient plant regeneration by somatic embryogenesis

Protocols for axillary shoot proliferation and somatic embryogenesis were developed for Dendranthema × grandiflora (Ramat.) Kitamura cv. Palisade White. Shoot tips were cultured on a modified Murashige and Skoog (MS) media supplemented with benzyl aminopurine (BA) and gibberellic acid (GA3) or BA, kinetin (Kin) and indole-3-acetic acid (IAA). The auxins indole -3-butyric acid (IBA) and IAA were used to induce rooting. Direct somatic embryogenesis was induced from leaf, internode’s stem and for the first time for chrysanthemums from petiole explants. Modified MS medium supplemented with 1 mg/L naphthalene acetic acid (NAA) or 2,4- dichlorophenoxyacetic acid (2,4-D), 0.1 mg/L BA, 200 mg/L casein hydrosylate (CH) and 290 mg/L proline was used for induction. Proliferation rate of 3.2 new microshoots per one inoculated was achieved when BA (0.1 mg/L) was used in combination with GA3 (0.5 mg/L). The number of roots per shoot was higher using IBA (0.5 mg/L), but IAA (2 mg/L) promoted longer roots. A high percentage of embryogenesis was induced by both combinations of plant growth regulators (PGRs). Leaf explants were most responsive, demonstrating the highest percentage of embryogenesis (97.9%), followed by petiole and internode’s stem explants (56.3 and 35.1%, respectively). The number of somatic embryos per embryogenic explant was also the highest on leaf explants; however, the best conversion rate (53.8%) of somatic embryos to plantlets was observed from petiole explants. For this reason, petiole explants are the most suitable type of explants for plant regeneration of chrysanthemum cv. Palisade White through somatic embryogenesis.Key words: Chrysanthemum, Dendranthema × grandiflora (Ramat.) Kitamura cv. Palisade White, micropropagation, direct somatic embryogenesis, explant type

Calvet Microcalorymetry - a New Suitable Method for Investigation of Polymerization Reactions

The method of Calvet microcalorimetry was used to follow the course of the spontaneous polymerization of styrene. Comparison of this method with widely used point-by-point methods has been performed and the great advantages of calorimetry are shown. Calorimetry measures continuously and directly the reaction rate independently from the physical state of the sample using only one sample for the whole conversion range. The accuracy and sen,sitivity achieved are better than those achieved with other methods. On the basis of these advantages Calvet microcalorimetry can be recommended as very promising method for the investigation of polymerization kinetics

VALIDITY LIMITS OF THE EXPRESSION FOR MEASURING SOIL RESISTIVITY BY THE WENNER METHOD ACCORDING TO IEEE STANDARD 81-1983

Za analizu rezultata i obavljanje mjerenja specifičnog otpora tla inženjerima su dane na raspolaganje smjernice i naputci različitih međunarodnih normi. Prilikom korištenja matematičkih izraza iz navedenih normi često nisu jasne okolnosti pod kojima su dobiveni navedeni izrazi. Jedan takav slučaj opisan je u ovom članku, a odnosi se na međunarodnu normu IEEE Std. 81-1983, izraz za prividni specifični otpor tla, a koji se odnosi na teorijski model i predviđanje mjernih rezultata dobivenih Wennerovim mjernim rasporedom elektroda. U IEEE Std. 81-1983 štapne elektrode su modelirane kao kuglaste, što u konačnici rezultira jednostavnim matematičkim izrazom za prividni specifični otpor tla. Zbog navedenog pojednostavljenja inženjeri nemaju uvid u granice valjanosti prema normi dobivenog izraza, odnosno njegovu točnost. Naime, pretpostavlja se da korisnik ima predznanje visokog obrazovanja, usmjeravajuće struke ili da je pohađao odgovarajuće tečajeve. Iz tog razloga u članku je detaljno prikazan izvod izraza za prividni specifični otpor tla u slučaju kada se mjerenje obavlja Wennerovom mjernom tehnikom. Izvodi su iscrpno komentirani kako bi iznesena građa bila razumljivija što širem krugu čitatelja. Dobiveni izraz uvažava stvarnu geometriju mjernih elektroda i utjecaj međusobne blizine elektroda na mjerenje. Na primjeru iz prakse uspoređeni su rezultati dobiveni izvedenim izrazom s predloženim izrazom prema međunarodnoj normi IEEE Std. 81-1983. Rezultati oba pristupa prikazani su grafički, analitički te diskutirani.For the analysis of soil resistivity results and measurement, engineers have guidelines and instructions from various international standards at their disposal. The circumstances under which the mathematical expressions in these standards were obtained are not always clear. One such case is described in this article and refers to the international IEEE Standard 81-1983, an expression for apparent soil resistivity, and refers to a theoretical model and the prediction and interpretation of measurement results obtained by using the Wenner method of electrode arrangement. In IEEE Std. 81-1983, rod electrodes are modeled as spherical, which ultimately results in a simplified mathematical expression for apparent soil resistivity. Due to this simplification, the expression in this standard does not provide engineers with insight into its validity limits, i.e. accuracy. It is assumed that the user is highly educated, specialized or has obtained the necessary training. Therefore, this article presents the derivation of the expression for apparent soil resistivity in detail when measurement is performed using the Wenner method. Exhaustive commentary on the derivations is provided so that the material presented will be understood by the widest possible circle of readers. The expression obtained takes the actual geometry of the measurement electrodes and the influence of the distance between the electrodes upon measurement into account. Using a practical example, the results obtained using the derived expression are compared to results obtained using the expression proposed according to the international IEEE Std. 81-1983. The results of both approaches are presented graphically and analytically, and are discussed

Consensus recommendations for the diagnosis, treatment and follow-up of inherited methylation disorders

Inherited methylation disorders are a group of rarely reported, probably largely underdiagnosed disorders affecting transmethylation processes in the metabolic pathway between methionine and homocysteine. These are methionine adenosyltransferase I/III, glycine N-methyltransferase, S-adenosylhomocysteine hydrolase and adenosine kinase deficiencies. This paper provides the first consensus recommendations for the diagnosis and management of methylation disorders. Following search of the literature and evaluation according to the SIGN-methodology of all reported patients with methylation defects, graded recommendations are provided in a structured way comprising diagnosis (clinical presentation, biochemical abnormalities, differential diagnosis, newborn screening, prenatal diagnosis), therapy and follow-up. Methylation disorders predominantly affect the liver, central nervous system and muscles, but clinical presentation can vary considerably between and within disorders. Although isolated hypermethioninemia is the biochemical hallmark of this group of disorders, it is not always present, especially in early infancy. Plasma S-adenosylmethionine and S-adenosylhomocysteine are key metabolites for the biochemical clarification of isolated hypermethioninemia. Mild hyperhomocysteinemia can be present in all methylation disorders. Methylation disorders do not qualify as primary targets of newborn screening. A low-methionine diet can be beneficial in patients with methionine adenosyltransferase I/III deficiency if plasma methionine concentrations exceed 800 μmol/L. There is some evidence that this diet may also be beneficial in patients with S-adenosylhomocysteine hydrolase and adenosine kinase deficiencies. S-adenosylmethionine supplementation may be useful in patients with methionine adenosyltransferase I/III deficiency. Recommendations given in this article are based on general principles and in practice should be adjusted individually according to patient's age, severity of the disease, clinical and laboratory findings

Exome sequencing reveals mutated SLC19A3 in patients with an early-infantile, lethal encephalopathy

To accomplish a diagnosis in patients with a rare unclassified disorder is difficult. In this study, we used magnetic resonance imaging pattern recognition analysis to identify patients with the same novel heritable disorder. Whole-exome sequencing was performed to discover the mutated gene. We identified seven patients sharing a previously undescribed magnetic resonance imaging pattern, characterized by initial swelling with T2 hyperintensity of the basal nuclei, thalami, cerebral white matter and cortex, pons and midbrain, followed by rarefaction or cystic degeneration of the white matter and, eventually, by progressive cerebral, cerebellar and brainstem atrophy. All patients developed a severe encephalopathy with rapid deterioration of neurological functions a few weeks after birth, followed by respiratory failure and death. Lactate was elevated in body fluids and on magnetic resonance spectroscopy in most patients. Whole-exome sequencing in a single patient revealed two predicted pathogenic, heterozygous missense mutations in the SLC19A3 gene, encoding the second thiamine transporter. Additional predicted pathogenic mutations and deletions were detected by Sanger sequencing in all six other patients. Pathology of brain tissue of two patients demonstrated severe cerebral atrophy and microscopic brain lesions similar to Leigh's syndrome. Although the localization of SLC19A3 expression in brain was similar in the two investigated patients compared to age-matched control subjects, the intensity of the immunoreactivity was increased. Previously published patients with SLC19A3 mutations have a milder clinical phenotype, no laboratory evidence of mitochondrial dysfunction and more limited lesions on magnetic resonance imaging. In some, cerebral atrophy has been reported. The identification of this new, severe, lethal phenotype characterized by subtotal brain degeneration broadens the phenotypic spectrum of SLC19A3 mutations. Recognition of the associated magnetic resonance imaging pattern allows a fast diagnosis in affected infant

Reproductive Performance of Late Pregnant Gilts Treated with Baypamun© before Farrowing

The aim of this study was to investigate whether the production results of pregnant gilts, grown under commercial farm conditions and moved from the sow keeping unit to the prefarrowing unit, could be increased by non-specific immunization with Baypamun© (Bayer, Leverkusen, Germany; BPM), an immune response modifier (IRM). We used three groups of pregnant gilts that obtained different treatments. Non-treated group A served as control; two experimental groups were treated on Day 6, 4 and 2 (group B), or on Day 5, 3 and 1 (group C), respectively, before their transfer from the sow keeping unit to the prefarrowing unit. The experimental gilts received i.m. 2 ml of IRM BPM, i.e. inactivated Parapoxovis virus (1 x 106.75 TCID50). Throughout the trial, the numbers of liveborn and stillborn piglets and the duration of farrowing were recorded. Variance analysis with the type of treatment as independent variable showed a significant difference between control (group A) and experimental group B in the number of liveborn piglets (P < 0.0001) as well as between group A and group B (P < 0.0001) or group C (P < 0.0001) in the number of stillborn piglets, respectively. No differences in duration of farrowing between groups were recorded

Novel cerebrospinal fluid biomarkers of glucose transporter type 1 deficiency syndrome: Implications beyond the brain's energy deficit

We used next-generation metabolic screening to identify new biomarkers for improved diagnosis and pathophysiological understanding of glucose transporter type 1 deficiency syndrome (GLUT1DS), comparing metabolic cerebrospinal fluid (CSF) profiles from 12 patients to those of 116 controls. This confirmed decreased CSF glucose and lactate levels in patients with GLUT1DS and increased glutamine at group level. We identified three novel biomarkers significantly decreased in patients, namely gluconic + galactonic acid, xylose-α1-3-glucose, and xylose-α1-3-xylose-α1-3-glucose, of which the latter two have not previously been identified in body fluids. CSF concentrations of gluconic + galactonic acid may be reduced as these metabolites could serve as alternative substrates for the pentose phosphate pathway. Xylose-α1-3-glucose and xylose-α1-3-xylose-α1-3-glucose may originate from glycosylated proteins; their decreased levels are hypothetically the consequence of insufficient glucose, one of two substrates for O-glucosylation. Since many proteins are O-glucosylated, this deficiency may affect cellular processes and thus contribute to GLUT1DS pathophysiology. The novel CSF biomarkers have the potential to improve the biochemical diagnosis of GLUT1DS. Our findings imply that brain glucose deficiency in GLUT1DS may cause disruptions at the cellular level that go beyond energy metabolism, underlining the importance of developing treatment strategies that directly target cerebral glucose uptake

Biallelic mutations in NBAS cause recurrent acute liver failure with onset in infancy

Acute liver failure (ALF) in infancy and childhood is a life-threatening emergency. Few conditions are known to cause recurrent acute liver failure (RALF), and in about 50% of cases, the underlying molecular cause remains unresolved. Exome sequencing in five unrelated individuals with fever-dependent RALF revealed biallelic mutations in NBAS. Subsequent Sanger sequencing of NBAS in 15 additional unrelated individuals with RALF or ALF identified compound heterozygous mutations in an additional six individuals from five families. Immunoblot analysis of mutant fibroblasts showed reduced protein levels of NBAS and its proposed interaction partner p31, both involved in retrograde transport between endoplasmic reticulum and Golgi. We recommend NBAS analysis in individuals with acute infantile liver failure, especially if triggered by fever