Positional vertigo afterwards maxillary dental implant surgery with bone regeneration

Benign paroxysmal positional vertigo (BPPV) is the most common form of vertigo. It is caused by loose otoconia from the utricle which, in certain positions, displaced the cupula of the posterior semicircular canal. BPPV most often is a result of aging. It also can occur after a blow to the head. Less common causes include a prolonged positioning on the back (supine) during some surgical procedures. Additionally one can include in this ethiopathogenesis the positioning required during the maxillary dental implant surgery with bone regeneration related to a forced head positioning and inner ear trauma induced by dental turbine noise working in the maxillary bone. Two cases of patients who suffered BPPV after undergoing maxillary dental implant with bone regeneration procedures are reported. Diagnosis and treatment are also described

Capacity fading mechanisms and origin of the capacity above 4.5 V of spinel lithium manganese oxides

textLithium ion batteries have become attractive for portable devices due to their high operating voltage, high energy density, low self-discharge, and long cycle life. Lithium ion cells currently use the layered LiCoO2 cathode, but cobalt is expensive and relatively toxic. In this regard, spinel LiMn2O4 has become appealing since manganese is inexpensive and environmentally benign. However, LiMn2O4 exhibits severe capacity fade. This dissertation explores the electrochemical performances of spinel oxides derived from LiMn2O4 in a wide voltage range of 3.5 to 5.2 V to understand the capacity fading mechanisms and the origin of the high voltage capacity above 4.5 V. From a systematic investigation of a series of singly substituted LiMn2-yMyO4 and doubly substituted LiMn2-y-zMyLizO4 (M = Li, Al, or transition metal) oxides, the doubly substituted LiMn2-y-zNiyLizO4 oxides are found to show superior cyclability, low irreversible capacity (IRC), high rate capability, low electrode resistance, and excellent storage performance compared to LiMn2O4 despite a similar manganese dissolution. For example, LiMn1.85Ni0.075Li0.075O4 retains more than 99 and 97 % of its initial capacity after 50 cycles at, respectively, 25 and 60 o C. Its excellent electrochemical performances are found to be due to the small lattice parameter difference between the two cubic phases formed in the two-phase region during cycling and the consequent low microstrain. This concept of minimizing the lattice parameter difference and microstrain could successfully enable the use of spinel lithium manganese oxides for electric vehicle applications. In contrast to the literature suggestions that other transition metal ions or excess oxygen are essential to impart the high voltage (> 4.5 V) capacity, spinel lithium manganese oxides free from other transition metal ions are found to show capacity above 4.5 V even with a significant amount of oxygen deficiency if there are extractable Li+ ions in the 8a tetrahedral sites after the oxidation state of manganese reaches 4+. In the presence of other transition metals, the reversibility of the high voltage capacity depends on the element replacing Mn3+, and it decreases in the order LiMn2-yNiyO4 > LiMn2-yCoyO4 ≈ LiMn2-y-zCoyLizO4 > LiMn2-y-zNiyLizO4. Based on the results, the capacity above 4.5 V in manganesebased spinel oxides could be understood to arise from a participation of the O2-:2p band or a hybridized band involving M3+/4+:3d (or M2+/3+:3d) and O2-:2p.Materials Science and Engineerin

DEVELOPMENT OF A DYNAMIC SIMULATION CODE FOR A VHTR-AIDED SI PROCESS

Abstract -In order to establish the optimal start-up method and to understand the dynamic behavior of the SI process coupled to a VHTR through a

Altered intrinsic local activity and cognitive dysfunction in HIV patients: A resting-state fMRI study.

PurposeTo characterize resting-state brain activation patterns and investigate altered areas for cognitive decline in HIV patients.MethodsTwelve male HIV patients with intact cognition (HIV-IC), 10 with HIV-associated neurocognitive disorder (HAND), and 11 male healthy controls (HC) underwent resting-state functional MRI (rsfMRI). Three rsfMRI values, regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and fractional ALFF (fALFF) were calculated and compared between groups. Correlation analyses were performed between rsfMRI values and neuropsychological tests.ResultsrsfMRI analyses revealed decreased rsfMRI values in the frontal areas, and increases in the posterior brain regions for both HIV-IC and HAND compared to HC. When directly compared to HIV-IC, HAND showed lower fALFF in the orbitofrontal cortex and higher ReHo in the primary sensorimotor area. Additionally, decreased orbitofrontal fALFF, increased sensorimotor ReHo, and a larger difference between the two values were highly correlated with decreased verbal memory and executive function in HIV patients.ConclusionsRegardless of cognitive status, altered local intrinsic activities were found in HIV patients. The orbitofrontal cortex and primary sensorimotor area were more disrupted in HAND relative to HIV-IC and correlated with behavioral performance, suggesting these areas are relevant to cognitive impairment in HIV patients