The role of charcoal on DTA curves of organo-clay complexes: an overview

DTA of organo-clay complexes supplemented by other thermal analysis methods supplies information on the thermal reactions, properties and stability of the complex, the amount and properties of the adsorbed water in the organo-clay and on the bonding between the organic species and the clay. It is used to identify the mineral to differentiate between various complexes composed of the same clay and the same organic ligand and to establish their composition. During the gradual heating in oxidizing atmospheres the adsorbed organic material is oxidized, giving rise to significant exothermic peaks. DTA curves of organo-clays are divided into three regions: (1) the dehydration of the clay, (2) the thermal oxidation of the organic material and (3) the dehydroxylation of the clay. The exothermic oxidation reaction occurring during the gradual heating of the sample takes place in two steps, in the range 200–500 °C, oxidation of organic hydrogen and formation of water and charcoal, and 400–750 °C, oxidation of charcoal and formation of CO₂. The exothermic peak temperatures depend on the mineral and on the organic compound and on the types of bonding between these two components of the organo-clay complex. The present communication concentrates in the role of the combustion of charcoal in the study of the fine structure of the complex and of the type of associations between the organic compound and the clay.     

Timber-framed partition walls and their restraining effect on warp in built-in wall studs – Models for twist

The shape of timber changes due to variations in moisture content (MC). Analytical models, which explain how the cladding restrains the timber studs that are prone to twist, are presented. The models are used for parametric studies of various properties, such as longitudinal shrinkage, torsional modulus of elasticity and cross-sectional size of the timber stud and stiffness of the cladding. With respect to twist, the bending stiffness of the cladding is of great importance. Large bending stiffness increases the restraint in the twist-prone studs and results in a straighter wall. Low torsional stiffness in the studs makes it easier for the cladding to restrain twist.     

Timber-framed partition walls and their restraining effect on warp in built-in wall studs – A model for spring

The shape of timber changes due to variations in moisture content (MC). A poor way of designing and/or erecting a structure may result in excessive deformation. An analytical model, which explains spring in a partition wall, is presented. The model is used for parametric studies of various properties such as longitudinal shrinkage coefficient, modulus of elasticity and cross-sectional size of the timber studs and stiffness of the cladding. With respect to spring, a problem is likely to occur when erecting a wall with single-sided cladding in a drying climate and the structure will benefit from relatively stiff studs and weak cladding.     

OPM/Web – Object-Process Methodology for Developing Web Applications

Web applications can be classified as hybrids between hypermedia and information systems. They have a relatively simple distributed architecture from the user viewpoint, but a complex dynamic architecture from the designer viewpoint. They need to respond to operation by an unlimited number of heterogeneously skilled users, address security and privacy concerns, access heterogeneous, up-to-date information sources, and exhibit dynamic behaviors that involve such processes as code transferring. Common system development methods can model some of these aspects, but none of them is sufficient to specify the large spectrum of Web application concepts and requirements. This paper introduces OPM/Web, an extension to the Object-Process Methodology (OPM) that satisfies the functional, structural and behavioral Web-based information system requirements. The main extensions of OPM/Web are adding properties of links to express requirements, such as those related to encryption; extending the zooming and unfolding facilities to increase modularity; cleanly separating declarations and instances of code to model code transferring; and adding global data integrity and control constraints to express dependence or temporal relations among (physically) separate modules. We present a case study that helps evaluate OPM/Web and compare it to an extension of the Unified Modeling Language (UML) for the Web application domain.     

Fuzzy and probability vectors as elements of a vector space

The problem of defining vector space operations on fuzzy and probability vectors is discussed. It is shown that such a definition is equivalent to choosing a 1-1 and onto mapping from the unit interval into the real axis. Although such a mapping cannot be continuous, it is suggested that under certain approximations a continuous mapping can be chosen. A characterization of some useful mappings with applications to image processing is also given.     

Saving Space by Fully Exploiting Invisible Transitions

Checking that a given finite state program satisfies a linear temporal logic property suffers from the state explosion problem. Often the resulting lack of available memory is more significant than any time limitations. One way to cope with this is to reduce the state graph used for model checking. We present an algorithm for constructing a state graph that is a projection of the program's state graph. The algorithm maintains the transitions and states that affect the truth of the property to be checked. Especially in conjunction with known partial order reduction algorithms, we show a substantial reduction in memory over using partial order methods alone, both in the precomputation stage, and in the result presented to a model checker. The price of the space reduction is a single additional traversal of the graph obtained with partial order reduction. As part of our space-saving methods, we present a new way to exploit Holzmann's Bit Hash Table, which assists us in solving the revisiting problem.     

Thyroid function in end stage renal disease and effects of frequent hemodialysis

Introduction: End‐stage renal disease (ESRD) is associated with perturbations in thyroid hormone concentrations and an increased prevalence of hypothyroidism. Few studies have examined the effects of hemodialysis dose or frequency on endogenous thyroid function. Methods: Within the Frequent Hemodialysis Network (FHN) trials, we examined the prevalence of hypothyroidism in patients with ESRD. Among those with endogenous thyroid function (without overt hyper/hypothyroidism or thyroid hormone supplementation), we examined the association of thyroid hormone concentration with multiple parameters of self‐reported health status, and physical and cognitive performance, and the effects of hemodialysis frequency on serum thyroid stimulating hormone (TSH), free thyroxine (FT4), and free tri‐iodothyronine (FT3) levels. Conventional thrice‐weekly hemodialysis was compared to in‐center (6 d/wk) hemodialysis (Daily Trial) and Nocturnal (6 nights/wk) home hemodialysis (Nocturnal Trial) over 12 months. Findings: Among 226 FHN Trial participants, the prevalence of hypothyroidism was 11% based on thyroid hormone treatment and/or serum TSH ≥8 mIU/mL. Among the remaining 195 participants (147 Daily, 48 Nocturnal) with endogenous thyroid function, TSH concentrations were modestly (directly) correlated with age (r = 0.16, P = 0.03) but not dialysis vintage. Circulating thyroid hormone levels were not associated with parameters of health status or physical and cognitive performance. Furthermore, frequent in‐center and nocturnal hemodialysis did not significantly change (baseline to month 12) TSH, FT4, or FT3 concentrations in patients with endogenous thyroid function. Discussion: Among patients receiving hemodialysis without overt hyper/hypothyroidism or thyroid hormone treatment, thyroid indices were not associated with multiple measures of health status and were not significantly altered with increased dialysis frequency.