Search results for "poro"
showing 10 items of 1943 documents
Study of Selective Adsorption of Gases by Calorimetry
2013
This chapter is devoted to the study of coadsorption of gases in nanoporous solids by using the differential calorimetry. In the first part, the thermodynamic principles of adsorption of gases are recalled. Some of them have already presented in chapter one. However a special attention has been paid here to the determination of the adsorption enthalpies and entropies and we focused on the selective adsorption of binary mixtures. Then the specific experimental technique based on the combination of differential calorimetry with manometry and gas phase chromatography or mass spectrometry is shown in details. In the last part, the thermodynamic concepts on coadsorption are illustrated with expe…
Some intriguing items in the history of adsorption
1994
Abstract Clay was already used in antiquity as a drying and bleaching agent, a carrier for paints, and for various medical purposes. Sand was applied for water desalination. Charcoal was recommended as an antidote Based on Lowitz' discovery of the decolorizing effect in 1785, charcoal was used for the purification first of sugar. The patents of Ostrejko in 1900 opened the way for its industrial application. Already in the Bible we find the description of an adsorption experiment. The systematic research began 1773 when Scheele observed the adsorption of air by charcoal using a volumetric apparatus. The first adsorption measuring instruments were hygrometers as described by Nicholas of Cues …
Study of the Pore Network of Dealuminated Faujasites by Water Vapor Adsorption
1991
Summary The adsorption and desorption isotherms of water vapor are drawn at 25°C for dealuminated HY zeolites upon framework Si/Al ratio. The isotherms are compared to that of the parent NaY zeolite. The isotherm changes in shape from the type I to the type IV with an hysteresis loop changing from the type H 4 to the type H 2 , as increases the Si/Al ratio. The POLANYI-DUBININ theory is used to determine the micropore volume accessible to water. It decreases with increasing Si/Al ratios, down to zero at a Si/Al ratio of 35. Such a result is accounted by the adsorption on the hydrophilic centers which are the cations (H + ) associated with the structural aluminium ions, each cation being coo…
Association between condylar asymmetry and temporo- mandibular disorders using 3D-CT
2011
Objectives: Using reconstructed three-dimensional computed tomography (3D-CT) models, the purpose of this study was to analyze and compare mandibular condyle morphology in patients with and without temporomandibular disorder (TMD). Study Design: Thirty-two patients were divided into two groups: the first comprised those with TMD (n=18), and the second those who did not have TMD (n=14). A CT of each patient was obtained and reconstructed as a 3D model. The 64 resulting 3D condylar models were evaluated for possible TMD-associated length, width and height asymmetries of the condylar process. Descriptive statistics were used to assess the results and student’s t tests applied to compare the tw…
BODY SIZE AT BIRTH, CHILDHOOD GROWTH, HIP FRACTURES IN OLDER AGE
2017
Childhood growth has been linked with bone properties in adulthood, whereas less is known about the contribution of early growth to bone fracture risk. We investigated the association of body size at birth and childhood growth with hip fractures and pharmacotherapy for osteoporosis in older age. Men and women, born full term, from the Helsinki Birth Cohort Study (n = 8345) were followed until the age of 68 to 80 years. Height and weight from birth to 11 years were obtained from health care records and diagnoses of hip fractures and osteoporosis drug purchases from national registers. Independent associations of each age period were analyzed using Cox models adjusted for age, childhood and a…
The effects of calorie restriction, intermittent fasting and vegetarian diets on bone health.
2019
Uncountable health care organizations, clinicians, and individuals are striving to prevent obesity and the many chronic medical conditions linked to it by advocating a healthy lifestyle that includes measures such as reducing dietary calorie intake (i.e., calorie restriction = CR and intermittent fasting = IF) or limiting/abolishing animal source foods (i.e., practices termed vegetarianism and veganism). Although these regimens are traditionally considered healthy, their real impact on bone health has yet to be established, and some studies have reported that they have negative effects on bone outcomes. The current work provides an overview of the studies carried out to examine the effect/s…
EMG-Assisted Muscle Force Driven Finite Element Model of the Knee Joint with Fibril-Reinforced Poroelastic Cartilages and Menisci.
2019
Abnormal mechanical loading is essential in the onset and progression of knee osteoarthritis. Combined musculoskeletal (MS) and finite element (FE) modeling is a typical method to estimate load distribution and tissue responses in the knee joint. However, earlier combined models mostly utilize static-optimization based MS models and muscle force driven FE models typically use elastic materials for soft tissues or analyze specific time points of gait. Therefore, here we develop an electromyography-assisted muscle force driven FE model with fibril-reinforced poro(visco)elastic cartilages and menisci to analyze knee joint loading during the stance phase of gait. Moreover, since ligament pre-st…
Correlation of the temporomandibular dysfunction classification index with cephalometric indicators of facial structure: a study on adult female subj…
2008
AIM: The aim of this study was to determine whether associations exist between temporomandibular dysfunction index (TMI) and craniofacial morphology. METHODS: The sample consisted of 30 symptomatic (mean age 28.3+/-6.7; range 24-39 years, TMI 0.48+/-0.21) and 30 asymptomatic women (mean age 27.4+/-9.2; range 22-42 years, TMI 0.1+/-0.05) seeking orthodontic treatment at Department of Dental Sciences ''''G. Messina'''', University of Palermo, who had routine lateral cephalograms. Symptoms and signs of temporomandibular joint dysfunction (TMD) were assessed by a standardized clinical examination and the TMI (a clinical measure of dysfunction used to evaluate the severity of TMD). Linear and an…
Electromyographic study of activity of the masseter and anterior temporalis muscles in patients with temporomandibular joint (TMJ) dysfuction : compa…
2010
Objectives: A comparison was made between the electromyographic patterns specific to patient with temporomandibular disorders and that of normal healthy patients. Study design: Electromyographic tests were carried out during rest and function of the masseter muscles and anterior temporalis muscles in a homogeneous group consisting of 95 patients for whom such pathology and its different degree of severity had been previously studied by means of a Helkimo Test. The electromyographic exploration results were compared to those of a control group consisting of 31 healthy subjects. Results: There were significant differences among patients with a different degree of clinical dysfunction, as well…
Long-term leisure time physical activity and properties of bone: A twin study
2009
Effects of physical activity on bone properties, when controlled for genetic effects, are not fully understood. We aimed to study the association between long-term leisure time physical activity (LTPA) and bone properties using twin pairs known to be discordant for leisure time physical activity for at least 30 yr. Volumetric BMD and geometric properties were measured at the tibia shaft and distal end using pQCT in 16 middle-aged (50-74 yr) same-sex twin pairs (seven monozygotic [MZ] and nine dizygotic [DZ] pairs) selected from a population-based cohort. Paired differences between active and inactive co-twins were studied. Active members of MZ twin pairs had larger cortical bone cross-secti…