bluuebunny/crossref_metadata_2025 huggingface dataset:
Costs of the construction and operation of irrigation systems in recreation and sports areas
Authors: Gulczyński Radosław , Przybyła Czesław
Published: February 2011

Costs of the construction and operation of irrigation systems in recreation and sports areas

The paper discusses the problems of investment costs of irrigation systems in recreation and sports objects and the costs of maintenance and operation of these systems. For this purpose, source materials referring to six objects realized in the years 2006-2007 in Konin district were analysed. Particular consideration was devoted to the irrigation system, water intake and costs of the construction and operation of the irrigation system in various operation conditions. Furthermore, cost analysis included the maintenance and operation of particular objects. In effect of these studies, the investment unit costs per square meter of area were calculated.
Effect of Droplet Size on Weed Control in Wheat
Authors: Esehaghbeygi Ali , Tadayyon Ali , Besharati Shahin
Published: February 2011

Effect of Droplet Size on Weed Control in Wheat

The efficacy of different water volume and nozzle systems, comprising spinning-discs with two disc speeds (low volume, LV), a spinning-cage rotary atomizer (median volume, MV), a flat fan nozzle Teejet-11004 (high volume, HV), and no weed control, were assessed for the application of 2,4-D to control weeds in irrigated wheat. The herbicide was applied at the tillering stage of cultivated wheat, Ghods variety. Sprayer nozzle performance was evaluated in terms of wheat grain yield, weed shoot biomass, and wheat residual (straw), at the research farm of Shahrekord University in 2007 and 2008. ANOVA analysis indicated that nozzle type, and the year had significant effects on grain yield and dry biomass of weeds at 5% confidence. There was a significant difference between the two years of the experiment for all variants. The results indicated that the median diameter volume using the spinning disc (low disc speed) for herbicide application, gave better weed control than others. The spinning disc nozzle decreased water use and so it was cheaper to operate. It did not, however, significantly improve herbicide efficacy, especially in dense canopies compared with the conventional flat fan nozzles. The spinning-disc had more droplet uniformity at high disc speeds compared with the cage rotary atomizer, but was more effective for weed control at low disc speeds.
Application of permeable reactive barriers near roads for chloride ions removal
Authors: Fronczyk Joanna , Pawluk Katarzyna , Michniak Marta
Published: February 2011

Application of permeable reactive barriers near roads for chloride ions removal

One of the most critical sources of pollutants are road run-offs. Road run-off is a complex mixture of toxicants e.g. heavy metals, de-icing agents, organic compounds and water suspensions of solid substances. One of the most negative impact on the environment has sodium chloride which is used as de-icing agent. In the case of incorrect environment protection in the vicinity of roads pollutants may migrate to groundwater causing hazard to sources of potable water. One of the methods to prevent the migration of pollutants to groundwater is imposing the flow of polluted water through a reactive material filling a permeable reactive barrier (PRB). This paper examines the feasibility of selected reactive materials for the reduction chlorides concentration in road run-offs. Four different reactive materials: zero valent-iron, activated carbon, zeolite and geza rock have been chosen for studies. The tests results indicated that the most popular reactive materials used in PRB technology, activated carbon and zero-valent iron, removed exhibited the highest efficiency in chloride ions removal. Moreover, the composition of road run-off in samples collected along roads in Warsaw was determinated.
Revised modelling of the post-AD 79 volcanic deposits of Somma-Vesuvius to reconstruct the pre-AD 79 topography of the Sarno River plain (Italy)
Authors: Vogel Sebastian , Märker Michael , Seiler Florian
Published: February 2011

Revised modelling of the post-AD 79 volcanic deposits of Somma-Vesuvius to reconstruct the pre-AD 79 topography of the Sarno River plain (Italy)

In this study the methodology proposed by Vogel & Märker (2010) to reconstruct the pre-AD 79 topography and paleo-environmental features of the Sarno River plain (Italy) was considerably revised and improved. The methodology is based on an extensive dataset of stratigraphical information from the entire Sarno River plain, a high-resolution present-day digital elevation model (DEM) and a classification and regression tree approach. The dataset was re-evaluated and 32 additional stratigraphical drillings were collected in areas that were not or insufficiently covered by previous stratigraphic data. Altogether, an assemblage of 1,840 drillings, containing information about the depth from the present-day surface to the pre-AD 79 paleo-surface (thickness of post-AD 79 deposits) and the character of the pre-AD 79 paleo-layer of the Sarno River plain was utilized. Moreover, an improved preprocessing of the input parameters attained a distinct progress in model performance in comparison to the previous model of Vogel & Märker (2010). Subsequently, a spatial model of the post-AD 79 deposits was generated. The modelled deposits were then used to reconstruct the pre-AD 79 topography of the Sarno River plain. Moreover, paleo-environmental and paleo-geomorphological features such as the paleo-coastline, the paleo-Sarno River and its floodplain, alluvial fans near the Tyrrhenian coast as well as abrasion terraces of historical and protohistorical coastlines were identified. This reconstruction represents a qualitative improvement of the previous work by Vogel & Märker (2010).
Geomorphological, mineralogical, and geochemical evidence of Pleistocene weathering conditions in the southern Italian Apennines
Authors: Di Leo Paola , Gioia Dario , Martino Claudio , Pappalardo Anna , Schiattarella Marcello
Published: February 2011

Geomorphological, mineralogical, and geochemical evidence of Pleistocene weathering conditions in the southern Italian Apennines

Pleistocene weathering, uplift rates, and mass movements have been studied and correlated in a key-area of the Italian southern Apennines. The study area is the Melandro River valley, developed in a tectonically-controlled Quaternary intermontane basin of the axial zone of the chain. The goal of this paper is to assess ages and geomorphic features of two paleo-landslides and to relate them to values of uplift rates and the climate conditions in the axial zone of the chain during the Pleistocene. Uplift rates have been estimated using elevation and age of flat erosional land surfaces. In the southern area of the basin, the landscape features a wide paleo-landslide which can be ascribed to the upper part of the Lower Pleistocene on the basis of relationships with Quaternary deposits and land surfaces. Another paleo-landslide, in the northern sector of the basin, can be referred to the beginning of the Upper Pleistocene. The correlation between the ages of the two landslides and the temporal trend of the uplift rates allowed us to hypothesize that mass movements occurred in response to uplift peaks that destabilized slopes. Additionally, deciphering weathering conditions by means of the analysis of mineralogical and geochemical signals from landslide deposits and weathered horizons allowed assessment of changes in paleoclimate scenarios during the Pleistocene. The deep weathering was probably caused by the onset of warm-humid climate conditions, which may have acted as a further factor triggering landslide movements in an area already destabilized by the rapid uplift.
Upper Maeotian-Lower Pontian "Transitional Strata" in the Taman Peninsula: stratigraphic position and paleogeographic interpretation
Authors: Radionova Eleonora , Golovina Larissa
Published: February 2011

Upper Maeotian-Lower Pontian "Transitional Strata" in the Taman Peninsula: stratigraphic position and paleogeographic interpretation

Three sections (Taman, Popov Kamen, and Zheleznyi Rog) of the Upper Maeotian-Lower Pontian sediments of the Taman Peninsula (Eastern Paratethys) have been studied. The sequences represent continuous successions of the Maeotian and Pontian sediments. The transitional Upper Maeotian-Lower Pontian relatively deep-water sediments were formed at the time when Eastern Paratethys was connected with other marine basins. The facies are represented by thin clay layers interbedded with laminated diatomites and contain unusual diatom and nannofossil associations. The small size of coccoliths and the absence of zonal markers indicate that the influx of marine waters took place in the stressed conditions of a restricted basin. Diatom assemblages are more diverse and include the open-marine speciesAzpeitiaaff.komuraeandThalassiosira maruyamicaand marine endemicsActinocyclusaff.paradoxus, Rhizosolenia bezrukovii, Hemiaulussp.,Nitzschia miocenicaof the tropicalNitzschia miocenicaZone and — the index species of nextThalassiosira convexaZone appear in these part of the sections. Three stages of the Mediterranean marine invasion are distinguished; during the first one the connection between basins was rather permanent, for the two others its character became pulsing and not stable. The possible duration of the invasion is estimated from 6.4 to 6.1 Ma and belongs to the Early Messinian — to pre-evaporate deposits and lower part of lower evaporate deposits.
Recent Rapid Climate Changes in Antarctic and their Influence on Low Diversity Ecosystems
Authors: Chwedorzewska Katarzyna J.
Published: February 2011

The geographic position, astronomic factors (e.g. the Earth’s maximum distance from the Sun during winter), ice cover and altitude are the main factors affecting the climate of the Antarctic, which is the coldest place on Earth. Parts of Antarctica are facing the most rapid rates of anthropogenic climate change currently seen on the planet. Climate changes are occurring throughout Antarctica, affecting three major groups of environmental variables of considerable biological significance: temperature, water, UV-B radiation.

Low diversity ecosystems are expected to be more vulnerable to global changes than high diversity ecosystems
Change in N and P Concentrations in Antarctic Streams as a Response to Change in Penguin Populations
Authors: Nędzarek Arkadiusz
Published: February 2011

This study presents changes in the concentrations of nitrogen and phosphorus in two streams in Western Antarctica (Admiralty Bay, King George Island, South Shetlands) that differ in trophic status. The results suggest a decline in concentrations of the determined forms of N and P between 2001 and 2005. The decrease ranged from 9.3% for reactive phosphorus to 73.2% for ammonium-nitrogen. Such inferred declines in N and P concentrations are considered to reflect reduced deposition on land of organic matter brought in from the seas by the penguins nesting in the area. The ultimate cause of this is in turn the steady decline in abundance that is being noted for these penguins.
Effects of Intermediates between Vitamins K2 and K3 on Mammalian DNA Polymerase Inhibition and Anti-Inflammatory Activity
Authors: Mizushina Yoshiyuki , Maeda Jun , Irino Yasuhiro , Nishida Masayuki , Nishiumi Shin , Kondo Yasuyuki , Nishio Kazuyuki , Kuramochi Kouji , Tsubaki Kazunori , Kuriyama Isoko , Azuma Takeshi , Yoshida Hiromi , Yoshida Masaru
Published: February 2011

Previously, we reported that vitamin K3 (VK3), but not VK1 or VK2 (=MK-4), inhibits the activity of human DNA polymerase γ (pol γ). In this study, we chemically synthesized three intermediate compounds between VK2 and VK3, namely MK-3, MK-2 and MK-1, and investigated the inhibitory effects of all five compounds on the activity of mammalian pols. Among these compounds, MK-2 was the strongest inhibitor of mammalian pols α, κ and λ, which belong to the B, Y and X families of pols, respectively; whereas VK3 was the strongest inhibitor of human pol γ, an A-family pol. MK-2 potently inhibited the activity of all animal species of pol tested, and its inhibitory effect on pol λ activity was the strongest with an IC50 value of 24.6 μM. However, MK-2 did not affect the activity of plant or prokaryotic pols, or that of other DNA metabolic enzymes such as primase of pol α, RNA polymerase, polynucleotide kinase or deoxyribonuclease I. Because we previously found a positive relationship between pol λ inhibition and anti-inflammatory action, we examined whether these compounds could inhibit inflammatory responses. Among the five compounds tested, MK-2 caused the greatest reduction in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced acute inflammation in mouse ear. In addition, in a cell culture system using mouse macrophages, MK-2 displayed the strongest suppression of the production of tumor necrosis factor (TNF)-α induced by lipopolysaccharide (LPS). Moreover, MK-2 was found to inhibit the action of nuclear factor (NF)-κB. In an in vivo mouse model of LPS-evoked acute inflammation, intraperitoneal injection of MK-2 in mice led to suppression of TNF-α production in serum. In conclusion, this study has identified VK2 and VK3 intermediates, such as MK-2, that are promising anti-inflammatory candidates.
The New Carotenoid Pigment Moraxanthin Is Associated with Toxic Microalgae
Authors: Mangoni Olga , Imperatore Concetta , Tomas Carmelo  R. , Costantino Valeria , Saggiomo Vincenzo , Mangoni Alfonso
Published: February 2011

The new pigment “moraxanthin” was found in natural samples from a fish mortality site in the Inland Bays of Delaware, USA. Pure cultures of the species, tentatively named Chattonella cf. verruculosa, and natural samples contained this pigment as a dominant carotenoid. The pigment, obtained from a 10 L culture of C. cf. verruculosa, was isolated and harvested by HPLC and its structure determined from MS and 1D- and 2D-NMR. The data identified this pigment as a new acylated form of vaucheriaxanthin called moraxanthin after the berry like algal cell. Its presence in pure cultures and in natural bloom samples indicates that moraxanthin is specific to C. cf. verruculosa and can be used as a marker of its presence when HPLC is used to analyze natural blooms samples.
Tracing colonial carolina boats to their European roots
Authors: Alford Michael B.
Published: February 2011

Les sources historiques et archéologiques démontrent que les bateaux monoxyles et ceux comportant des éléments monoxyles étaient des embarcations d'un type courant en Caroline du Nord et du Sud aux XVIIIe et XIXe s. Elles permettent également de constater que les techniques de construction utilisées n'avaient pas les origines nord-européennes ou méditerranéennes habituellement attendues. Des études récentes ont mis en évidence la forte corrélation existant entre certaines traditions de construction navale du sud-ouest de la France et les découvertes faites en Caroline. D'après les données historiques, ces pratiques auraient été introduites en Caroline avant 1700 par des réfugiés huguenots français. Cette influence ancienne transparaît dans les méthodes caractérisant un type de construction navale en bois pratiqué encore de nos jours en Caroline du Nord.
ORGANISATIONAL CHANGE AND DEVELOPMENT: PERSPECTIVES ON THEORY AND PRACTICE
Authors: Rees Christopher J.
Published: February 2011

„Organisational change and development: Perspectives on theory and practice" Journal of Business Economics & Management, 9(2), p. 87-89
ANALYSIS OF INCIDENCES OF COLLAPSED BUILDINGS IN LAGOS METROPOLIS, NIGERIA
Authors: Oni Ayotunde Olawande
Published: February 2011

Building collapses in Lagos metropolis have become worrisome to residents, developers, and Government. This study examined the incidences of collapsed buildings in Lagos metropolis over a thirty‐year period. Time series analysis was carried out to determine the past and predict direction of the future occurrences. In addition, a process of inference from reports on investigations of past occurrences was adopted to establish causes of building collapses in the study area. Spatial analysis of the collapses showed high concentration in swampy terrain that was reclaimed in the past. The study recommends, amongst other things, comprehensive investigation of the geophysical characteristics of the affected locations towards finding lasting solution to the menace.

Santruka

Lagose griūvantys pastatai kelia nerima gyventojams, vystytojams ir vyriausybei. Šiame tyrime nagrinejamas pastatu griuvumo dažnumas Lagose per trisdešimt metu. Atlikta laiko eilučiu analize, siekiant nustatyti buvusius atvejus ir numatyti būsimu atveju tendencijas. Be to, siekiant nustatyti, del kokiu priežasčiu tiriamoje teritorijoje griūva pastatai, buvo pasirinktas išvadu procesas, pagristas ankstesniu atveju tyrimo ataskaitomis. Erdvine griuvimu analize parode didele koncentracija pelketose vietovese, kurios anksčiau buvo melioruotos. Be kitu dalyku, tyrime rekomenduojama atlikti išsamu paveiktu vietoviu geofiziniu savybiu tyrima, siekiant rasti ilgalaiki sprendima, kaip išvengti šios gresmes.
« The private and uninteresting history of a single town ? »
Authors: Sweet Rosemary H.
Published: February 2011

Cet article répertorie les différents types d’écrits historiques que l’on peut trouver dans les villes du dix-huitième siècle et analyse leur impact tant auprès des lettrés de l’époque, que des historiens actuels, spécialistes d’histoire urbaine. En raison d’un développement rapide des villes de provinces au dix-huitième siècle, l’histoire urbaine devint un genre reconnu et bien établi ; cependant ses racines remontent à une période bien antérieure. Garder une trace écrite des faits urbains a permis de légitimer la gouvernance municipale et ce, depuis le Moyen Âge. De fait, les chroniques urbaines représentent un enjeu crucial de ce type d’histoire. D’autres sources y ont également joué un rôle : les relevés topographiques, les études des antiquités ou les guides pour les voyageurs, toutes formes de documents historiques à prendre en compte dans l’étude de cette évolution. La plupart de ces écrits présente une société qui se police et devient plus prospère, offrant ainsi un point de vue intéressant et nouveau sur le rôle de l’histoire et de sa place dans la construction de l’identité urbaine, ainsi que sur la réponse des villes de province face à une urbanisation rapide et constante au dix-huitième siècle.
L'historien de la ville et l'espace public
Authors: Coulomb Clarisse
Published: February 2011

Les histoires des villes connurent une fortune croissante en France au cours de la période moderne, les réécritures, rééditions, abrégés se multipliant au XVIII e siècle. Il ne s’agit pas ici d’étudier le contenu de ces histoires, mais les textes qui les encadrent, dédicaces et préfaces. Comment se situe l’historien de la ville dans l’espace public ? L’étude d’un corpus constitué d’une centaine de textes publiés du XVII e siècle à la fin du XVIII e siècle permet d’observer un basculement : si, au début de la période, l’historien se confond avec son objet, s’effaçant derrière les édiles commanditaires et la communauté savante locale, on assiste à une progressive affirmation de l’auteur, écrivant désormais contre les autorités locales politiques ou savantes et en appelant au jugement du public. Ce glissement reflète la dissolution des « petites patries » dans un espace national, mais aussi la réactivité du monde culturel urbain face aux mutations du champ littéraire et sa participation aux débats nationaux non seulement intellectuels, mais aussi politiques.
L'Union des écrivains
Authors: Dragomir Lucia
Published: February 2011

Résumé Les politiques culturelles des États communistes entendent unifier les communautés des écrivains pour les diriger plus facilement vers des fonctions idéologiques précises et les contrôler. C’est ainsi qu’est créée l’Union des écrivains, institution littéraire monopolistique. Ce modèle est reproduit après la Seconde Guerre mondiale dans les pays d’Europe centrale et orientale passés sous régime communiste. Il est suivi tout au long de la période communiste autant par des stratégies internes que par une coopération intense avec les institutions homologues de l’espace soviétique. Les documents laissent pourtant transparaître des évolutions qui montrent les limites de l’Unions des écrivains, qui vont parfois jusqu’à la mise en doute du modèle et même jusqu’à la transformation de certaines unions en lieu de contestation du pouvoir politique, violant donc leur contrat initial. Les tensions internes des unions et certaines tensions enregistrées dans les échanges littéraires des « démocraties populaires » semblent nier l’existence d’une harmonie parfaite dans le bloc soviétique. Ces institutions représentent, de ce fait, un lieu propice à l’interrogation des significations et de la pertinence de la notion de bloc soviétique.
Le réalisme socialiste et ses modèles internationaux
Authors: Bazin Jérôme
Published: February 2011

Résumé L’article pose la question des modèles artistiques qui circulaient dans les pays socialistes, à partir de l’exemple des arts plastiques en RDA. Le seul modèle revendiqué était l’art soviétique, pourtant peu repris par les artistes est-allemands engagés dans la création du réalisme socialiste. Les formes réalistes instituées en modèle viennent plutôt des périphéries du bloc, d’Italie, de France et du Mexique. À partir des années 1960, la marginalisation du réalisme socialiste dans le monde de l’art socialiste ne marque cependant pas la fin de ces modèles, ni la fin d’une recherche à un niveau international d’une peinture manifestant une solidarité politique.
Les échanges universitaires, la logique de bloc et l'esprit de guerre froide
Authors: Verdery Katherine , Faure Justine
Published: February 2011

Résumé Katherine Verdery, anthropologue américaine spécialiste de la Roumanie socialiste, revient dans cet entretien sur plusieurs points importants de son parcours dans la guerre froide. Elle montre tout d’abord combien elle fut, intellectuellement et professionnellement, influencée par les effets structurants du conflit Est-Ouest. Elle souligne aussi combien la possibilité d’aller travailler sur le terrain, derrière le rideau de fer, changea sa perception du socialisme et lui permit de dissiper l’esprit de guerre froide. Elle revient enfin sur la question de la circulation des savoirs en anthropologie entre les États-Unis et la Roumanie, montrant que les obstacles rencontrés furent parfois créés par les contraintes de la guerre froide mais aussi souvent tout simplement liés à deux traditions intellectuelles différentes.
Transcriptomes of the B and T Lineages Compared by Multiplatform Microarray Profiling
Authors: Painter Michio W. , Davis Scott , Hardy Richard R. , Mathis Diane , Benoist Christophe ,   The Immunological Genome Project Consortium, Zhou Yan , Shinton Susan , Hardy Richard , Asinovski Natasha , Davis Scott , Ergun Ayla , Ericson Jeff , Heng Tracy , Hill Jonathan , Hyatt Gordon , Gray Daniel , Painter Michio , Laplace Catherine , Ortiz-Lopez Adriana , Mathis Diane , Benoist Christophe , Bellemare-Pelletier Angelique , Elpek Kutlu , Turley Shannon , Best Adam , Knell Jamie , Goldrath Ananda , Sun Joseph , Bezman Natalie , Lanier Lewis , Bogunovic Milena , Helft Julie , Sachidanandam Ravi , Merad Miriam , Jakubzick Claudia , Gautier Emmanuel , Randolph Gwendalyn , Cohen Nadia , Brenner Michael , Collins Jim , Costello James , Jianu Radu , Laidlaw David , Jojic Vladimir , Koller Daphne , Malhotra Nidhi , Sylvia Katelyn , Narayan Kavitha , Kang Joonsoo , Shay Tal , Regev Aviv
Published: February 2011

T and B lymphocytes are developmentally and functionally related cells of the immune system, representing the two major branches of adaptive immunity. Although originating from a common precursor, they play very different roles: T cells contribute to and drive cell-mediated immunity, whereas B cells secrete Abs. Because of their functional importance and well-characterized differentiation pathways, T and B lymphocytes are ideal cell types with which to understand how functional differences are encoded at the transcriptional level. Although there has been a great deal of interest in defining regulatory factors that distinguish T and B cells, a truly genomewide view of the transcriptional differences between these two cells types has not yet been taken. To obtain a more global perspective of the transcriptional differences underlying T and B cells, we exploited the statistical power of combinatorial profiling on different microarray platforms, and the breadth of the Immunological Genome Project gene expression database, to generate robust differential signatures. We find that differential expression in T and B cells is pervasive, with the majority of transcripts showing statistically significant differences. These distinguishing characteristics are acquired gradually, through all stages of B and T differentiation. In contrast, very few T versus B signature genes are uniquely expressed in these lineages, but are shared throughout immune cells.
Subcellular localization and distribution of the reduced folate carrier in normal rat tissues
Authors: Hinken M. , Halwachs S. , Kneuer C. , Honscha W.
Published: February 2011

The reduced folate carrier (Rfc1; Slc19a1) mediated transport of reduced folates and antifolate drugs such as methotrexate (MTX) play an essential role in physiological folate homeostasis and MTX cancer chemotherapy. As no systematic reports are as yet available correlating Rfc1 gene expression and protein levels in all tissues crucial for folate and antifolate uptake, storage or elimination, we investigated gene and protein expression of rat Rfc1 (rRfc1) in selected tissues. This included the generation of a specific anti-rRfc1 antibody. Rabbits were immunised with isolated rRfc1 peptides producing specific anti-rRfc1 antiserum targeted to the intracellular C-terminus of the carrier. Using RT-PCR analysis, high rRfc1 transcript levels were detected in colon, kidney, brain, thymus, and spleen. Moderate rRfc1 gene expression was observed in small intestine, liver, bone marrow, lung, and testes whereas transcript levels were negligible in heart, skeletal muscle or leukocytes. Immunohistochemical analyses revealed strong carrier expression in the apical membrane of tunica mucosa epithelial cells of small intestine and colon, in the brush-border membrane of choroid plexus epithelial cells or in endothelial cells of small vessels in brain and heart. Additionally, high rRfc1 protein levels were localized in the basolateral membrane of renal tubular epithelial cells, in the plasma membrane of periportal hepatocytes, and sertoli cells of the testes. Taken together, our results demonstrated that rRfc1 is expressed almost ubiquitously but to very different levels. The predominant tissue distribution supports the essential role of Rfc1 in physiological folate homeostasis. Moreover, our results may contribute to understand antifolate pharmacokinetics and selected organ toxicity associated with MTX chemotherapy.
Altered alkaline phosphatase activity in obese Zucker rats liver respect to lean Zucker and Wistar rats discussed in terms of all putative roles ascribed to the enzyme
Authors: Bertone V. , Tarantola E. , Ferrigno A. , Gringeri E. , Barni S. , Vairetti M. , Freitas I.
Published: February 2011

Biliary complications often lead to acute and chronic liver injury after orthotopic liver transplantation (OLT). Bile composition and secretion depend on the integrated action of all the components of the biliary tree, starting from hepatocytes. Fatty livers are often discarded as grafts for OLT, since they are extremely vulnerable to conventional cold storage (CS). However, the insufficiency of donors has stimulated research to improve the usage of such marginal organs as well as grafts. Our group has recently developed a machine perfusion system at subnormothermic temperature (20°C; MP20) that allows a marked improvement in preservation of fatty and even of normal rat livers as compared with CS. We sought to evaluate the response of the biliary tree of fatty liver to MP20, and a suitable marker was essential to this purpose. Alkaline phosphatase (AlkP, EC 3.1.3.1), frequently used as marker of membrane transport in hepatocytes and bile ducts, was our first choice. Since no histochemical data were available on AlkP distribution and activity in fatty liver, we have first settled to investigate AlkP activity in the steatotic liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. The AlkP reaction in Wistar rats was in accordance with the existing data and, in particular, was present in bile canaliculi of hepatocytes in the periportal region and midzone, in the canals of Hering and in small bile ducts but not in large bile ducts. In lean ZR liver the AlkP reaction in Hering canals and small bile ducts was similar to Wistar rat liver but hepatocytes had lower canalicular activity and besides presented moderate basolateral reaction. The difference between lean Zucker and Wistar rats, both phenotypically normal animals, could be related to the fact that lean Zucker rats are genotypically heterozygous for a recessive mutated allele. In fatty liver, the activity in ductules and small bile ducts was unchanged, but most hepatocytes were devoid of AlkP activity with the exception of clusters of macrosteatotic hepatocytes in the mid-zone, where the reaction was intense in basolateral domains and in distorted canaliculi, a typical pattern of cholestasis. The interpretation of these data was hindered by the fact that the physiological role of AlkP is still under debate. In the present study, the various functions proposed for the role of the enzyme in bile canaliculi and in cholangiocytes are reviewed. Independently of the AlkP role, our data suggest that AlkP does not seem to be a reliable marker to study the initial step of bile production during OLT of fatty livers, but may still be used to investigate the behaviour of bile ductules and small bile ducts.
Some Causes of Variation in the Quality of Raw Rubber and Latex. The Sol: Gel Ratio in Relation to the Ultimate Physical Properties of Rubber
Authors: Spence D. , Ferry John D.
Published: February 2011

When raw rubber is treated with solvents such as benzene or ether, dissolution is gradual and never complete; a swollen residue remains which disperses extremely slowly, if at all. The soluble portion is generally called the “sol”, and the insoluble the “gel”, and although these need not be considered as two distinct components, it is convenient, in view of the existing state of our knowledge regarding them, to continue to use this terminology. The nature of the gel fraction of raw rubber has long been under discussion. Gladstone and Hibbert were inclined to regard the less soluble modification as a product produced by heat during the drying of the latex and rubber, whereas Fessenden and Seeligman came to the conclusion that the two components were isomerides, a view which has long persisted. Weber, as the result of studies of the gel fraction of Para rubber, contended that the soluble and insoluble fractions were not identical in composition. Later it was shown by one of us that the gel fraction contained proteins which could be removed only by suitable treatment of the latex before coagulation or by digestion of the rubber in presence of acids or alkali. These early observations and records are of more than historical interest, as they foreshadow in large measure almost all that has been made known regarding the origin and nature of the gel fraction in raw rubber. The vast array of recent literature on this subject is admirably reviewed in the English edition of Memmler's “Handbuch der Kautschukwissenschaft”.
Structural Studies of the Vulcanization of Rubber under Stretch
Authors: Hauser E. A. , Smith I. N.
Published: February 2011

Just one hundred years have passed since the changes were discovered which rubber undergoes when mixed with sulfur and heated. Although “vulcanization”, as this reaction and the changes subsequent thereto have been termed, must be considered the most important development in the rubber industry, we are still far from being in a position to offer a fully satisfactory explanation for this phenomenon. Nevertheless we have been able to improve our concept of these changes by the application of such modern methods of research as x-ray diffraction, and recent attempts to shed more light on the phenomenon from a strictly chemical point of view also have been successful. The outstanding results of the latter work are the definite proof that the changes in physical properties, which become noticeable during vulcanization, show no correlation with the amount of combined sulfur or with the total loss in unsaturation. The experiments offered no direct experimental evidence as to the existence of specific chemical bonds or linkages in vulcanized rubber. However, it could be definitely ascertained that chemical reactions involving the double bonds of the hydrocarbon and its combination with the vulcanizing agent, in one way or another, are necessary to produce a vulcanized structure responsible for the observed changes in properties.
Temperature Coefficient of Vulcanization
Authors: Gerke R. H.
Published: February 2011

One hundred years ago rubber was the only available substance having the property of long-range elasticity which makes rubber so useful to man. The invention of vulcanization tremendously increased the usefulness of rubber, since it decreased the plastic flow at elevated temperatures and increased the resistance to hardening at low temperatures. It is now the general consensus that vulcanization is caused by a chemical reaction or at least is attended by a chemical reaction. The fact that vulcanization is the result of a chemical reaction is an all-important factor in controlling the nature of the manufacturing processes in the rubber industry. The existence of a temperature coefficient of vulcanization like other chemical reactions exerts a powerful influence on the nature of the manufacturing processes. Thus, vulcanized rubber is made by a thermosetting rather than thermoplastic process.
Vulcanization of Rubber in an Ultra-High Frequency Field. A Preliminary Communication
Authors: Medvedchuk P. I. , Khimudis N. S. , Nemirovskii Ya N.
Published: February 2011

There is no doubt about the theoretical interest and the technological significance of the action of ultra-high frequency on high-molecular compounds in general and on raw rubber in particular. The published data available on the effect of high-frequency currents on rubber indicate certain practical advantages and a high speed of “radiovulcanization” compared with the common thermal process. It is claimed that this new method can be applied to rubber articles of considerable thickness. Preliminary experiments in an investigation of the influence of an alternating electric field of ultra-high frequency on thin films and benzene solutions of rubber have given some positive results. In the present article no attempt is made to give the underlying theoretical principles and conclusions, since they require further experimental verification. In general, it can be said that ultra-high frequency currents produce not only a thermal effect but have a specific action on the objects under investigation.
Light Scattering in Stretched Rubber
Authors: Schwarzenbach H. A.
Published: February 2011

It is already known that when pure rubber is stretched in one direction it acquires a lustre. This means that light falling upon it is scattered with appreciably different intensities at various angles to the direction in which the rubber is stretched. In view of this and in connection with earlier experiments, a study of the scattering of visible light by stretched rubber was undertaken and the first results are reported in a brief way in the present paper. First of all, however, it is well to describe the experimental apparatus and technique which were used. A practically parallel, sharp beam of light was produced, the direction of which may be represented by the X-axis of a system of right-angle coordinates. The rubber test-specimen, in the form of a strip, was placed in such a position in the path of this beam of light that it was illuminated by the beam at right angles to its surface. In other words, the specimen lay in the YZ plane of the coördinate system and by means of a special device it could be stretched in the Z direction. At a suitable distance behind the test-specimen a smooth, transparent paper screen was placed, likewise at right angles to the direction of the beam of light. The distribution of the scattered light around the bright spot formed by the transmitted light could be observed by eye and could be photographed by a camera. Samples of rubber as nearly pure as possible and containing no fillers were examined, including not only films prepared from pure unvulcanized and partially vulcanized latex, but also strips prepared from commercial sheets of “patent rubber” and from Para rubber.
Mechanical Properties of Raw and Vulcanized Rubbers during Periodic Deformation
Authors: Kornfel'd M. , Poznyak V.
Published: February 2011

The construction of an apparatus for measuring the modulus of elasticity and the mechanical losses in raw and vulcanized rubbers during the periodical deformation of compression is described. With the aid of this device it is possible to measure these characteristics at frequencies from 10 to 50 cycles per second for relative compression deformations from 1 to 50 per cent and in a wide range of temperatures. The relation between temperature and modulus of elasticity and mechanical losses was studied at 30 cycles per second for various grades of raw and vulcanized rubbers and a general regularity of this dependence was determined. In the solution of technical problems such as the construction of automobile tire treads, the behavior of rubber under conditions of rapidly changing periodic deformation is highly important. Here the two characteristics of rubber: the dynamic modulus of elasticity and the magnitude of that part of work of deformation which is irreversibly spent during one cycle (mechanical losses) are of the greatest interest. In previous studies of these properties, three basic methods have been used:
A Critical Analysis of the T-50 Test for State of Vulcanization
Authors: Vila George R.
Published: February 2011

It is the consensus of opinion in the literature that the T-50 test is reliable, sensitive and easy to perform. The present analysis of the T-50 test, compared with other methods for determining state of cure, indicates it to be more sensitive and consistent than stress-strain data and easier to perform than sulfur analyses. In addition it seems to be a more constant function of state of cure than combined sulfur, and detects other factors contributing to state of cure which, for convenience and lack of a true understanding of their exact nature, may be referred to collectively as “vulcanization potential”. Plotting the logarithm of T-50, expressed as absolute temperature, against the logarithm of the time of cure seems to hold interesting possibilities for future study.
Determination of the Water Absorption of Crude Rubber and of Vulcanized Rubber
Authors: van Dalfsen J. W.
Published: February 2011

In the introduction the purpose of the investigation is described which is the development of a method suitable for the determination of the water absorption of crude and vulcanized rubber, and which, in conjunction with ash and nitrogen determinations is especially adapted to the testing of purified rubber. The conditions which affect the results of water determinations are reviewed, with special reference to the formulas of Taylor and Kemp, which make it possible, within certain limits, to compare results obtained by different determination methods. The reasons for selecting the foregoing method of determination of water absorption are described. It is pointed out that water absorption depends to different degrees on the time of vulcanization. In the rubber-sulfur mixture which was chosen, the influence of the degree of vulcanization is small, so that it is sufficient to vulcanize all types of rubber for the same length of time. At the same time it is shown that the results obtained by immersion of rubber for 7 and 25 hours at 80° C. still sufficiently agree with the values computed from the formulas of Taylor and Kemp. A method of measuring water absorption is described in detail. The question arises to what extent rubber manufacturers may use this method, in conjunction with ash and nitrogen determinations, method for estimating the quality of purified rubber. Rubber manufacturers are urged to give their opinion of this proposed method. Some other method will be considered if it should appear that manufacturers prefer this other method.
Contributions to the Analysis of Rubber. IV. Determination of Manganese in Crude Rubber; in Rubber Mixtures and in Fillers
Authors: Dekker P.
Published: February 2011

A scheme for the determination of manganese in mineral fillers, compounding ingredients, crude rubber, rubber mixtures and rubberized materials is described. It is shown that with this method the use of potassium persulfate and two drops of orthophosphoric acid, as proposed by Kehren for the oxidation of colorless manganese ions to red permanganate ions, is advisable. When potassium periodate is used, small quantities of manganese escape detection. It is further shown that there is no appreciable difference between concentration with nitric acid and evaporation with hydrochloric acid and a little sulfuric acid. If, however, the ash is decomposed by soda-potash mixture, the manganese contents are considerably higher. Doubtless these higher values can be accounted for by manganese compounds which are occluded in silicates, and which can be regarded as harmless. A reliable method for the decomposition of the manganese compounds is therefore desirable. The results of analyses of the manganese contents of a large number of various materials are tabulated, and the maximum manganese contents of various materials allowed by the Netherlands Government Rubber Institute are given.
Coagulation of Rubber Latex and Its Control
Authors: Twiss D. F. , Amphlett P. H.
Published: February 2011

Removal of ammonia or dialysis narrows the range of pH over which coagulation of preserved Hevea latex occurs with acetic acid; the addition of saline substances, e. g., potassium sulfate or ammonium acetate, broadens it. These results accord with the view that the rubber particles carry an adsorbed protein layer. The delayed coagulant effect of sodium fluosilicate, of which use is made in the manufacture of rubber articles, arises not merely from the gradual development of acidity, but also from the concurrent formation of zinc ions. If the zinc ions become effective at too high a pH value, the coagula may be undesirably weak. This can be prevented by the additional presence of a sparingly soluble zinc salt, e. g., zinc sulfite. The coagulant activity of sodium fluosilicate can also be controlled by the addition of salts which decrease its solubility or its rate of hydrolysis. At ordinary temperatures ammonium persulfate is too slow to be a satisfactory delayed coagulant, but its action can be accelerated by the addition of suitable reducing substances.
Van Harpen's Hydratant Acid
Authors: Altman R. F. A.
Published: February 2011

In this article it is shown that the so-called hydratant acid or H-acid of van Harpen is not a definite chemical substance (a hydroxyamino acid), but is a mixture mainly of proteins and higher fat acids. The fat acids are responsible for the coalescent effect of H-acid when added to B latex.
The Concentration of Latex by Centrifugal Machines
Authors: Piddlesden J. H.
Published: February 2011

Rubber latex has become a very important raw material and finds many applications, ranging from the proofing of fabrics and impregnation of paper to the manufacture of elastic threads, can-sealing compounds, adhesives, and upholstery. A large amount of research work has been carried out in the East with a view to supplying preserved latex suitable for these processes. The latex as it leaves the tree has an average dry rubber content of about 33 to 35 per cent, and is so unstable that it will coagulate within a few hours unless a preservative is added. Ammonia has been found to be a suitable preservative and, in spite of the continued search for new materials, it remains in general use. The problem of concentrating the latex to avoid the shipment of surplus water arose early. Three methods for carrying out this operation were developed, namely, centrifugal concentration, creaming by the addition of gums and mucilages, and evaporation. A fourth method, utilizing the phenomena of electrodialysis, has recently been the subject of commercial development. The advent of concentrated latex widened the field of latex applications, since the concentrated products found uses for which preserved field latex was not suitable. For many processes the properties and applications of the latex or concentrate are now perhaps more important that the question of shipping cost. Various types of product, described briefly below, are obtained from the different processes of concentration.
Butyl Rubber. A New Hydrocarbon Product
Authors: Thomas R. M. , Lightbown I. E. , Sparks W. J. , Frolich P. K. , Murphree E. V.
Published: February 2011

The present distinction between the thoughts expressed by the terms synthetic rubber and rubber synthesis is indicative of the changes in viewpoint on which current progress in the duplication of rubberlike properties is based. For almost fifty years after the discovery by Williams that isoprene is the fundamental structural unit of rubber, research was directed toward rubber synthesis. Bouchardat, Tilden, Wallach, Hoffman, Mathews, and Harries all made valuable contributions to the chemistry of rubberlike products from isoprene. That none of them accomplished the purpose of synthesizing rubber is an accepted fact. In the preparation of a rubberlike material from dimethylbutadiene, Kondakow departed from classical attempts at rubber synthesis, and laid the foundation for the first commercial “synthetic rubber”, the German wartime “methyl rubber”. The tradition that rubber properties were related to high unsaturation persisted, and has led to numerous theories of elastic behavior based on geometric structures resulting from unsaturated linkages. Whitby and Staudinger questioned the importance of unsaturation in determining rubberlike behavior, but encountered some difficulty in finding adequate support for this view, owing to the poor elastic properties of the practical examples available to them. Our studies on polymers of the simple monoölefins, which have been in progress for the past ten years, have led to some interesting conclusions in regard to this point. It was shown that high-molecular-weight linear polymers derived from simple olefins, such as the butylenes, possess a majority of the properties characteristic of rubber. Only the susceptibility to chemical action can definitely be attributed to the unsaturation of the natural rubber molecule. Physical properties which appear not to be intrinsically dependent on the carbon-double bond-carbon configuration are: tensile strength, elasticity, rebound, elastic memory, x-ray structure, mechanical orientation, electrical properties, and fractional solubility. It was, however, conclusively demonstrated that the saturated polymers are not capable of vulcanization in conventional manner.