Electrochemical Properties and Crystal Structure of Li+ / H+ Cation-exchanged LiNiO2

LiNiO2 has high energy density but easily reacts with moisture in the atmosphere and deteriorates. We performed qualitative and quantitative evaluations of the degraded phase of LiNiO2 and the influence of the structural change on the electrochemical properties of the phase. Li1-xHxNiO2 phase with cation exchange between Li+ and H+ was confirmed by thermogravimetric analysis and Karl Fischer titration measurement. As the H concentration in LiNiO2 increased, the rate capability deteriorated, especially in the low-temperature range and under low state of charge. Experimental and density functional theory (DFT) calculation results suggested that this outcome was due to increased activation energy of Li+ diffusion owing to cation exchange. Rietveld analysis of X-ray diffraction and DFT calculation confirmed that the c lattice parameter and Li-O layer reduced because of the Li+/H+ cation exchange. These results indicate that LiNiO2 modified in the atmosphere has a narrowed Li-O layer, which is the Li diffusion path, and the rate characteristics are degraded.Comment: 8 pages, 11 figure

First-Principles-Based Insight into Electrochemical Reactivity in a Cobalt-Carbonate-Hydrate Pseudocapacitor

Cobalt carbonate hydroxide (CCH) is a pseudocapacitive material with remarkably high capacitance and cycle stability. Previously, it was reported that CCH pseudocapacitive materials are orthorhombic in nature. Recent structural characterization has revealed that they are hexagonal in nature; however, their H positions still remain unclear. In this work, we carried out first-principles simulations to identify the H positions. Through the simulations, we could consider various fundamental deprotonation reactions inside the crystal and computationally evaluate the electromotive forces (EMF) of the deprotonation ($V_\mathrm{dp}$). Compared with the experimental potential window of the reaction ($< 0.6$ V (vs. saturated calomel electrode (SCE))), the computed $V_\mathrm{dp}$ (vs. SCE) value ($3.05$ V) was beyond the potential window, indicating that deprotonation never occurred inside the crystal. This may be attributed to the strongly formed hydrogen-bonds (H-bonds) in the crystal, thereby leading to the structural stabilization. We further investigated the crystal anisotropy in an actual capacitive material by considering the growth mechanism of the CCH crystal. By associating our X-ray diffraction (XRD) peak simulations with experimental structural analysis, we found that the H-bonds formed between CCH $\{(\bar{1}\bar{1}\bar{1}), (2\bar{1}\bar{1}), (2\bar{1}1)\}$ planes (approximately parallel to $ab$-plane) can result in 1-D growth (stacked along with $c$-axis)

Interface modelling for {\it ab initio} evaluation of contact angle on a metallic surface

Controlling the contact angles of the wettability is an important issue especially in industrial applications. Establishing its {\it ab initio} predictions is hence a topic of great interest. For the predictions, it is required to setup a model of the adsorption structure of liquid molecules on a surface. The appropriate setting is expected to depend on whether the surface is of insulating or metallic materials, the latter of which is the target of the present study while all preceding {\it ab initio} studies have worked on the former. Since the feasibility of {\it ab initio} evaluations relies on the approximation of the liquid-gas interface energy evaluated roughly by the crystal ice, it would be a natural choice to take the periodic honeycomb array of the water molecules as the adsorbing model of water on the surface. Although the periodic model have successfully been used for the preceding treatments of insulating surfaces, we found for the case with metallic surfaces that the periodic model gives worse prediction to reproduce experimental values. Rather than that, the models with isolated water multimers are found to give better predictions. The ambiguity of the models about the size of multimers and the coverage is found to be small ($\sim\pm 10^{\circ}$), and is averaged over to give a plausible value based on the Boltzmann weight with the adsorbing energies. The procedure we are providing can generally be applicable to any of wettability on the surfaces of metallic materials.Comment: 4 page

Ruptured anterior paraclinoid aneurysms

The purpose of this study was to evaluate cases of subarachnoid hemorrhage (SAH) from ruptured anterior (dorsal) paraclinoid aneurysms. Anterior paraclinoid aneurysms are defined as aneurysms arising from the anterolateral wall of the proximal internal carotid artery without any relationship to an arterial branch. Between 1991 and 2008, a total of 159 patients with 169 paraclinoid aneurysms were treated at the Shinshu University Hospital and its affiliated hospitals. A retrospective analysis was carried out using charts, operation records, operation videos, and neuroimagings. Twenty six patients had anterior paraclinoid aneurysm. Six patients presented with SAH. Three aneurysms were saccular and the others were blister-like aneurysms based on operative findings. Neck laceration or premature rupture frequently happened during the clipping surgery even though the aneurysm was saccular type. The treatment of a ruptured anterior paraclinoid aneurysm is quite difficult. Trapping and bypass would be recommended for such fragile aneurysms.ArticleNEUROSURGICAL REVIEW. 34(1):49-54 (2011)journal articl

Urgent open embolectomy for cardioembolic cervical internal carotid artery occlusion

Acute ischemic stroke attributable to cervical internal carotid artery (ICA) occlusion is frequently associated with severe disability or death and is usually caused by atherosclerosis. By contrast, the cardioembolic cervical ICA occlusion is rare, and feasibility of urgent recanalization remains unclear. We present the first study in the literature that focuses on urgent open embolectomy for the treatment of cardioembolic cervical ICA occlusion. A retrospective review of the charts for patients undergoing open embolectomy was performed. Between April 2006 and September 2007, 640 consecutive patients with acute ischemic stroke were treated. Of them, three patients (0.47%) with the acute complete cardioembolic cervical ICA occlusion underwent urgent open embolectomy. All patients presented with profound neurological deficits and atrial fibrillation. The urgent open embolectomy achieved complete recanalization in all patients without any complications. All emboli in three patients were very large and fibrinous in histological findings. Two of three patients showed rapid improvement in neurological functions after surgical treatments. The cardioembolic occlusion of the cervical ICA is rare, but its possibility should be considered in patients with acute ischemic stroke suffering profound neurological deficits and atrial fibrillation. Urgent open embolectomy may be a treatment option to obtain successful recanalization for cardioembolic cervical ICA occlusion and is recommended because it is technically easier and similar to carotid endarterectomy.ArticleNEUROSURGICAL REVIEW. 33(3):341-348 (2010)journal articl

Safe and minimally invasive laminoplastic laminotomy using an ultrasonic bone curette for spinal surgery: technical note

Background: Ultrasonic surgical aspirators have been used mainly for removing brain tumors. Because of their longitudinal and torsional tip, they are used for cutting the bone structures in spinal surgery installing a scalpel-type tip. The purpose of this report is to describe the effectiveness and surgical pitfalls of an ultrasonic bone curette in laminoplastic laminotomy and hemilaminotomy. Methods: We present 12 patients who underwent laminoplastic laminotomy and hemilaminotomy. We used a SONOPET UST-2001 ultrasonic bone curette with HB-05S handpieces (M and M Co, Ltd, Tokyo, Japan). After a tumor was removed, titanium plates were used for the laminoplastic laminotomy and hemilaminotomy. The technical advantage of an ultrasonic bone curette and procedure-related complication were examined. Results: There were no major procedure-related complications such as cord injury. Wound infection and subcutaneous fluid collection caused by cerebrospinal fluid leakage did not occur for reconstruction of posterior bony structure. In 1 patient with calcified dura mater associated with tumor, dural tear occurred. The width of the tip was narrow enough for resected laminae to be fused postoperatively, and spinal instability did not occur in all cases. Conclusion: The scalpel-type ultrasonic bone curette is useful for cutting bone and effective for reconstruction of the laminae. Laminotomy with an ultrasonic bone curette is safe and minimally invasive. To prevent dural tear, we recommend drilling laminae to make the bone thin as the first step, followed by cutting the remaining laminae using a bone curette especially in cases with calcified or tense dura mater.ArticleSURGICAL NEUROLOGY. 72(5):470-475 (2009)journal articl

Association between timing of speech and language therapy initiation and outcomes among post-extubation dysphagia patients: a multicenter retrospective cohort study

Background Post-extubation dysphagia (PED) is recognized as a common complication in the intensive care unit (ICU). Speech and language therapy (SLT) can potentially help improve PED; however, the impact of the timing of SLT initiation on persistent PED has not been well investigated. This study aimed to examine the timing of SLT initiation and its effect on patient outcomes after extubation in the ICU. Methods We conducted this multicenter, retrospective, cohort study, collecting data from eight ICUs in Japan. Patients aged >= 20 years with orotracheal intubation and mechanical ventilation for longer than 48 h, and those who received SLT due to PED, defined as patients with modified water swallowing test scores of 3 or lower, were included. The primary outcome was dysphagia at hospital discharge, defined as functional oral intake scale score < 5 or death after extubation. Secondary outcomes included dysphagia or death at the seventh, 14th, or 28th day after extubation, aspiration pneumonia, and in-hospital mortality. Associations between the timing of SLT initiation and outcomes were determined using multivariable logistic regression. Results A total of 272 patients were included. Of them, 82 (30.1%) patients exhibited dysphagia or death at hospital discharge, and their time spans from extubation to SLT initiation were 1.0 days. The primary outcome revealed that every day of delay in SLT initiation post-extubation was associated with dysphagia or death at hospital discharge (adjusted odds ratio (AOR), 1.09; 95% CI, 1.02-1.18). Similarly, secondary outcomes showed associations between this per day delay in SLT initiation and dysphagia or death at the seventh day (AOR, 1.28; 95% CI, 1.05-1.55), 14th day (AOR, 1.34; 95% CI, 1.13-1.58), or 28th day (AOR, 1.21; 95% CI, 1.07-1.36) after extubation and occurrence of aspiration pneumonia (AOR, 1.09; 95% CI, 1.02-1.17), while per day delay in post-extubation SLT initiation did not affect in-hospital mortality (AOR, 1.04; 95% CI, 0.97-1.12). Conclusions Delayed initiation of SLT in PED patients was associated with persistent dysphagia or death. Early initiation of SLT may prevent this complication post-extubation. A randomized controlled study is needed to validate these results

High concentrations of omega-3 fatty acids are associated with the development of atrial fibrillation in the Japanese population

The favorable effect of fish oils rich in n-3 polyunsaturated fatty acids (PUFAs) on the development of atrial fibrillation (AF) is controversial. The relationship between the serum concentrations of n-3 PUFAs and the incidence of AF is unclear; therefore, in the present study, we aimed to elucidate this relationship. We evaluated the serum concentrations of n-3 PUFAs in 110 patients with AF, 46 patients with ischemic heart disease (IHD) and no AF, and 36 healthy volunteers. Thirty-six patients had a history of IHD (IHD-AF group) and 74 did not (L-AF group). The eicosapentaenoic acid (EPA) levels in the L-AF group were higher than those in the IHD-AF and control groups (117 +/- A 64, 76 +/- A 30, and 68 +/- A 23 mu g/ml, respectively); the docosahexaenoic acid (DHA) levels showed the same pattern (170 +/- A 50, 127 +/- A 27, and 126 +/- A 35 mu g/ml, respectively). In both the L-AF and IHD-AF groups, the EPA levels in patients with persistent and permanent AF were higher than those in patients with paroxysmal AF (L-AF 131 +/- A 74 vs. 105 +/- A 51 mu g/ml; IHD-AF 82 +/- A 28 vs 70 +/- A 33 mu g/ml). Multivariate analysis showed that cases of AF were associated with higher levels of EPA but not DHA. In this Japanese population study, the EPA and DHA levels in patients with L-AF were higher than those in normal subjects. In particular, the EPA level was associated with the incidence of AF. These findings suggest that an excess of EPA might be a precipitating factor of AF.ArticleHEART AND VESSELS. 28(4):497-504 (2013)journal articl