INVESTIGATION OF PHASE TRANSITION BEHAVIORS AND TRANSITION MECHANISMS OF NAT-TOPOLOGY ZEOLITES IN T-P(H2O) SPACE

Thesis (Ph.D.) - Indiana University, Geological Sciences, 2011NAT-topology zeolites, namely natrolite (Na-bearing), mesolite (Na/Ca-bearing), and scolecite (Ca-bearing), consist of a three-dimensional host framework of (Al2Si3)O10 chains, with structural "pores" that contain reactive guest cations and H2O molecules. The nature of structural interactions between a host framework and guest cations and H2O molecules defines the character of phase transitions, which depend on the chemistry of the guests and rely on the symmetry (topology) of the host framework. X-ray diffraction and synchrotron X-ray total scattering experiments coupled with appropriate modeling methods showed the existence of different dehydration (heating)/phase transition behaviors under high- and low-P(H2O) conditions in these zeolites. Infrared spectroscopic studies of the dynamic interactions among the guest cation-H2O complexes and host frameworks allowed characterization of host-guest interactions as a function of T and P(H2O). Structural analyses reconciled these data and showed that different structural evolutions result from the cooperative processes in which the thermal behaviors of cations-H2O complexes are coupled with the framework symmetry constraints through direct bonding interactions. These results showed for the first time that the extent of coupling under specific T and P(H2O) conditions influences the flexibility of the structure and ultimately drives structural changes. The determined bulk thermodynamic behaviors in the NAT system were consistent with the observed structural behaviors. The computed apparent enthalpies of dehydration in these zeolites reflect strong dependence not only on guest cation chemistry but also on the local hydrogen bonding configurations

An Empirical Study Of Flow Experiences In Social Network Sites

Social network sites (SNS) have simplified and amplified social interaction between online users. The unique hedonic-oriented features provide experiential motives for SNS users. Although SNS is growing popularity, a number of questions remain to be addressed concerning the usage of SNS: What are experiential motives for SNS users? What is the relationship between flow experiences and behavioural intentions within the SNS context? Given the novelty of SNS phenomenon and its unexplored potential in many fields, this study develops a conceptual model derived from reference studies on online services and social psychology. The present study proposes four flow experiences of SNS users such as perceived enjoyment, concentration, escape and social interaction to represent the multidimensional aspect of flow instead of a single dimension. To investigate the research model, this study apply structural equation mode(SEM) analysis with 342 valid replies. As a result, this empirical study indicated that perceived enjoyment was the most important flow experience with SNS, followed by escape and social interaction. Concentration was not a significant predictor of behavioral intentions toward SNS

Understanding Repeat Purchase Intentions And Uncertainty In The Context Of Online Shopping

The distant and impersonal nature of e-commerce (EC) and the unpredictability of the Internet infrastructure generate an implicit uncertainty around online transactions. Moreover, customer repeat purchasing is critical to the e-commerce vendor’s survival and success. However, few studies explain online repeat purchase from an uncertainty perspective. The purpose of this study is to propose a conceptual model to examine the sources of uncertainty and types of uncertainty in an online transaction, which affect online repeat purchase intentions. We drew on uncertainty and online repeat purchase literature to formulate a conceptual model that identifies the sources of uncertainty, and three types of uncertainty (seller uncertainty, product uncertainty and environmental uncertainty) are respectively proposed as formative second-order constructs. The proposed structural model is empirically tested with data from 554 experienced online shoppers, and then analyzed using Structure Equation Model (SEM). The results show that seller uncertainty and environmental uncertainty have a negative effect on repeat purchase intentions. Implications for theory and practice and suggestions for future research are discussed

KINETIC EFFECTS ON THE LOWER EXTREMITY DURING PLYOMETRIC JUMP

INTRODUCTION: Plyometric exercises are a series of cyclical activities of muscle stretch and shortening. Jumping and landing are the major movements of plyometric exercises. Previous researches reported that the plyometric training can increase the proprioception in lower extremities. It also reported that plyometric jump exercise has great assistance to increase muscle strength of lower limbs. However, a few of published researches had studied the joint loading of lower limbs in each movement of plyimetric jump. Understanding of the loading on the lower limbs is greatly helpful to decide the proper exercise prescription for the subjects who had suffered musculoskeletal injury and in the period of rehabilitation. The purpose of this study is to estimate the joint kinetics of lower limbs in depth jump

Radiosurgery for Vestibular Schwannomas

BackgroundRadiosurgery has been established as an important alternative to microsurgery. We report our experience with radiosurgery for tumor control and the complications of unilateral vestibular schwannomas.MethodsWe reviewed our early experience regarding clinical presentation, management and outcomes in 45 patients with acoustic schwannomas who underwent gamma knife stereotactic radiosurgery. The median follow-up period was 25 months (range, 6-48 months). Thirteen patients had undergone 1 or more previous resections before radiosurgery; 32 underwent radiosurgery as the first procedure. Median tumor volume was 4.5 mL (range, 0.5-30.0), and median radiotherapy dose was 11.5 Gy (range, 10.5-14.0 Gy).ResultsTumor control was achieved in 43 patients (95.6%). Loss of central contrast enhancement was a characteristic change and was noted in 29 patients (64.4%). Reduction in tumor size was shown in 15 patients (33.3%). Thirteen patients (28.9%) had good or serviceable hearing preoperatively, and in all of these, the preoperative status was retained immediately after radiosurgery. At follow-up, however, 10 patients (76.9%) had preserved hearing and 3 (23.1%) had reduced hearing on the treated side. Hearing in 1 patient that was not serviceable preoperatively later improved to a serviceable level. No patients had delayed facial palsy or lower cranial nerve dysfunction, but one had delayed trigeminal sensory loss.ConclusionRadiosurgery achieved a high tumor control rate and a relatively low post-radiosurgical complication rate for acoustic neuromas

Interpretable Fully Convolutional Classification of Intrapapillary Capillary Loops for Real-Time Detection of Early Squamous Neoplasia

In this work, we have concentrated our efforts on the interpretability of classification results coming from a fully convolutional neural network. Motivated by the classification of oesophageal tissue for real-time detection of early squamous neoplasia, the most frequent kind of oesophageal cancer in Asia, we present a new dataset and a novel deep learning method that by means of deep supervision and a newly introduced concept, the embedded Class Activation Map (eCAM), focuses on the interpretability of results as a design constraint of a convolutional network. We present a new approach to visualise attention that aims to give some insights on those areas of the oesophageal tissue that lead a network to conclude that the images belong to a particular class and compare them with those visual features employed by clinicians to produce a clinical diagnosis. In comparison to a baseline method which does not feature deep supervision but provides attention by grafting Class Activation Maps, we improve the F1-score from 87.3% to 92.7% and provide more detailed attention maps

Slipped Capital Femoral Epiphysis as a Complication of Growth Hormone Therapy

Slipped capital femoral epiphysis (SCFE) is a rare complication of growth hormone (GH) therapy. Here, we report three patients who developed SCFE during GH therapy. The first two patients had hypopituitarism and had started GH therapy at the age of 15 years 6 months and 13 years 9 months, respectively. SCFE developed 4 years and 1 year after GH therapy, respectively. The third patient had Prader-Willi syndrome with obesity and hypogonadism and began GH therapy at the age of 12 years and 11 months. SCFE developed 2 months after starting GH therapy. Pain over the hip joints or over the knees is an early sign of SCFE. Despite recommendation, none of the three patients continued GH therapy. A high index of suspicion during GH therapy in patients at high risk of SCFE is important for early diagnosis and appropriate management. [J Formos Med Assoc 2007;106(2 Suppl):S46-S50