Magnetism in lithium-oxygen discharge product.

Lu, Jun,Jung, Hun-Ji,Lau, Kah Chun,Zhang, Zhengcheng,Schlueter, John A,Du, Peng,Assary, Rajeev S,Greeley, Jeffrey,Ferguson, Glen A,Wang, Hsien-Hau,Hassoun, Jusef,Iddir, Hakim,Zhou, Jigang,Zuin, Lucia Wiley-VCH 2013 ChemSusChem Vol.6 No.7

<P>Nonaqueous lithium-oxygen batteries have a much superior theoretical gravimetric energy density compared to conventional lithium-ion batteries, and thus could render long-range electric vehicles a reality. A molecular-level understanding of the reversible formation of lithium peroxide in these batteries, the properties of major/minor discharge products, and the stability of the nonaqueous electrolytes is required to achieve successful lithium-oxygen batteries. We demonstrate that the major discharge product formed in the lithium-oxygen cell, lithium peroxide, exhibits a magnetic moment. These results are based on dc-magnetization measurements and a lithium-oxygen cell containing an ether-based electrolyte. The results are unexpected because bulk lithium peroxide has a significant band gap. Density functional calculations predict that superoxide-type surface oxygen groups with unpaired electrons exist on stoichiometric lithium peroxide crystalline surfaces and on nanoparticle surfaces; these computational results are consistent with the magnetic measurement of the discharged lithium peroxide product as well as EPR measurements on commercial lithium peroxide. The presence of superoxide-type surface oxygen groups with spin can play a role in the reversible formation and decomposition of lithium peroxide as well as the reversible formation and decomposition of electrolyte molecules.</P>

Increased Stability Toward Oxygen Reduction Products for Lithium-Air Batteries with Oligoether-Functionalized Silane Electrolytes

Zhang, Zhengcheng,Lu, Jun,Assary, Rajeev S.,Du, Peng,Wang, Hsien-Hau,Sun, Yang-Kook,Qin, Yan,Lau, Kah Chun,Greeley, Jeffrey,Redfern, Paul C.,Iddir, Hakim,Curtiss, Larry A.,Amine, Khalil American Chemical Society 2011 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.115 No.51

<P>The successful development of Li-air batteries would significantly increase the possibility of extending the range of electric vehicles. There is much evidence that typical organic carbonate based electrolytes used in lithium ion batteries form lithium carbonates from reaction with oxygen reduction products during discharge in lithium-air cells so more stable electrolytes need to be found. This combined experimental and computational study of an electrolyte based on a tri(ethylene glycol)-substituted trimethylsilane (<ext-link xlink:type='simple'>1NM3</ext-link>) provides evidence that the ethers are more stable toward oxygen reduction discharge species. X-ray photoelectron spectroscopy (XPS) and FTIR experiments show that only lithium oxides and no carbonates are formed when <ext-link xlink:type='simple'>1NM3</ext-link> electrolyte is used. In contrast XPS shows that propylene carbonate (PC) in the same cell configuration decomposes to form lithium carbonates during discharge. Density functional calculations of probable decomposition reaction pathways involving solvated oxygen reduction species confirm that oligoether substituted silanes, as well as other ethers, are more stable to the oxygen reduction products than propylene carbonate. These results indicate that the choice of electrolyte plays a key role in the performance of Li-air batteries.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2011/jpccck.2011.115.issue-51/jp2087412/production/images/medium/jp-2011-087412_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp2087412'>ACS Electronic Supporting Info</A></P>

Cervical Disc Replacement: Trends, Costs, and Complications

Jain Nickul Saral,Nguyen Ailene,Formanek Blake,Alluri Ram,Buser Zorica,Hah Ray,Wang Jeffrey Chun 대한척추외과학회 2020 Asian Spine Journal Vol.14 No.5

Study Design: Retrospective review of insurance database.Purpose: To investigate national trends, complications, and costs after cervical disc replacement (CDR) using an administrative insurance database representative of the United States population.Overview of Literature: As CDR continues to be used to treat patients with cervical stenosis, it is important to gain a better understanding of its use on a national level, potential complications, and cost. This information will allow for optimal patient counseling, risk stratification, and healthcare cost assessments. Several prior studies have investigated complications associated with CDR, but they have been limited by small sample size, single institution experiences, limited follow-up, and potential conflicts of interest.Methods: Patients who underwent single or multilevel CDR between 2007 and 2015 were identified using an insurance database. We collected data on annual trends, reimbursement costs, patient demographic information, hospital information, and information on complications from the time of operation to 1 year postoperative.Results: Total of 293 patients underwent either single or multilevel CDR. The number of procedures increased nonlinearly over time at an average of 17% per year, with a greater increase seen in the outpatient setting. Less than 3.7% of patients had new onset pain within 1 year after CDR. Within 1 year, 12.3% of patients reported a mechanical and/or bone-related complication. There were no patients who indicated a new nerve injury within 6 months of follow-up. Less than 3.7% of patients presented with dysphagia or dysphonia within 6 months, infection within 3 months, or a revision or reoperation within 1 year. Average reimbursement for single-level inpatient versus outpatient CDR was $33,696.28 and $34,675.12, respectively (p =0.29).Conclusions: This study demonstrated that the use of CDR continued to increase. The most common complication was mechanical and/or bone-related, and cost analysis demonstrated no significant difference between inpatient and outpatient CDR.

Patterns of Lumbar Disc Degeneration: Magnetic Resonance Imaging Analysis in Symptomatic Subjects

Ruangchainikom Monchai,Daubs Michael D.,Suzuki Akinobu,Xiong Chengjie,Hayashi Tetsuo,Scott Trevor P.,Phan Kevin,Wang Jeffrey Chun 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.6

Study Design: Cross-sectional study. Purpose: To evaluate lumbar disc degeneration (LDD) on magnetic resonance imaging (MRI) in symptomatic subjects to accumulate baseline data on the pattern of degeneration. Overview of Literature: LDD plays an important role in the diagnosis and treatment of low-back pain in patients. Few studies have focused on the pattern of LDD to understand how the lumbar spine ages. Methods: This study included 1,095 patients (mean age, 44.29 years; range, 16–85 years) who underwent upright lumbar MRI. LDD was graded into five categories (I–V). Positive LDD was defined as grade III or greater. The prevalence and pattern of LDD were analyzed, and the correlations between age and total grade of LDD were evaluated. Results: The average number of LDD levels and the total grade of LDD increased with age. LDD moved cephalad with age. The rate of LDD increased rapidly during the decade before the prevalence of LDD and became >50%. In the single-level LDD group, the levels L5–S1 were the most common levels (60.3%). In the two-level group, L4–L5 and L5–S1 were the most common levels (53.5%). In the three-level group, L3–L4, L4–L5, and L5–S1 were the most common levels (55.7%). In the multilevel LDD group, contiguous multilevel disc degeneration (CMDD) was more common than the skipped level disc degeneration (SLDD). The levels L4–L5 were the most common levels in the CMDD group, and L5–S1 were the most common levels among SLDD. Conclusions: LDD was found to correlate with age, and the specific patterns and rates of LDD depended on lumbar disc level and age. These LDD pattern data can be used before spinal procedures to predict the probability of natural LDD progression with age.

Trends and Costs of External Electrical Bone Stimulators and Grafting Materials in Anterior Lumbar Interbody Fusion

Anthony D’Oro,Zorica Buser,Darrel Scott Brodke,박종범,Sangwook Tim Yoon,Jim Aimen Youssef,Hans-Joerg Meisel,Kristen Emmanuel Radcliff,Patrick Hsieh,Jeffrey Chun Wang 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.6

Study Design: Retrospective review. Purpose: To identify the trends in stimulator use, pair those trends with various grafting materials, and determine the influence of stimulators on the risk of revision surgery. Overview of Literature: A large number of studies has reported beneficial effects of electromagnetic energy in healing long bone fractures. However, there are few clinical studies regarding the use of electrical stimulators in spinal fusion. Methods: We used insurance billing codes to identify patients with lumbar disc degeneration who underwent anterior lumbar interbody fusion (ALIF). Comparisons between patients who did and did not receive electrical stimulators following surgery were performed using logistic regression analysis, chi-square test, and odds ratio (OR) analysis. Results: Approximately 19% of the patients (495/2,613) received external stimulators following ALIF surgery. There was a slight increase in stimulator use from 2008 to 2014 (multi-level R 2=0.08, single-level R 2=0.05). Patients who underwent multi-level procedures were more likely to receive stimulators than patients who underwent single-level procedures (p <0.05; OR, 3.72; 95% confidence interval, 3.02–4.57). Grafting options associated with most frequent stimulator use were bone marrow aspirates (BMA) plus autograft or allograft for single-level and allograft alone for multi-level procedures. In both cohorts, patients treated with bone morphogenetic proteins were least likely to receive electrical stimulators (p <0.05). Patients who received stimulation generally had higher reimbursements. Concurrent posterior lumbar fusion (PLF) (ALIF+PLF) increased the likelihood of receiving stimulators (p <0.05). Patients who received electrical stimulators had similar revision rates as those who did not receive stimulation (p >0.05), except those in the multilevel ALIF+PLF cohort, wherein the patients who underwent stimulation had higher rates of revision surgery. Conclusions: Concurrent PLF or multi-level procedures increased patients’ likelihood of receiving stimulators, however, the presence of comorbidities did not. Patients who received BMA plus autograft or allograft were more likely to receive stimulation. Patients with and without bone stimulators had similar rates of revision surgery.