Multi-functional electrolyte for lithium-ion batteries, A

2016 Summer.Includes bibliographical references.Thermal management of lithium-ion batteries (LIBs) is paramount for multi-cell packs, such as those found in electric vehicles, to ensure safe and sustainable operation. Thermal management systems (TMSs) maintain cell temperatures well below those associated with capacity fade and thermal runaway to ensure safe operation and prolong the useful life of the pack. Current TMSs employ single-phase liquid cooling to the exterior surfaces of every cell, decreasing the volumetric and gravimetric energy density of the pack. In the present study, a novel, internal TMS that utilizes a multi-functional electrolyte (MFE) is investigated, which contains a volatile co-solvent that boils upon heat absorption in small channels in the positive electrode of the cell. The inert fluid HFE-7000 is investigated as the volatile co-solvent in the MFE (1 M LiTFSI in 1:1 HFE-7000/ethyl methyl carbonate by volume) for the proposed TMS. In the first phase of the study, the baseline electrochemical performance of the MFE is determined by conductivity, electrochemical stability window, half and full cell cycling with lithium iron phosphate (LiFePO4), lithium titanate oxide (Li4Ti5O12), and copper antimonide (Cu2Sb), and impedance spectroscopy measurements. The results show that the MFE containing HFE-7000 has comparable stability and cycling performance to a conventional lithium-ion electrolyte (1 M LiPF6 in 3:7 ethylene carbonate/diethyl carbonate by weight). The MFE-containing cells had higher impedance than carbonate-only cells, indicating reduced passivation capability on the electrodes. Additional investigation is warranted to refine the binary MFE mixture by the addition of solid electrolyte interphase (SEI) stabilizing additives. To validate the thermal and electrochemical performance of the MFE, Cu2Sb and LiFePO4 are used in a full cell architecture with the MFE in a custom electrolyte boiling facility. The facility enables direct viewing of the vapor generation within the channel in the positive electrode and characterizes the galvanostatic electrochemical performance. Test results show that the LiFePO4/Cu2Sb cell is capable of operation even when a portion of the more volatile HFE-7000 is continuously evaporated under an extreme heat flux, proving the concept of a MFE. The conclusions presented in this work inform the future development of the proposed internal TMS

Planning a Rural Fire Protection Service

Fire remains one of the major problems of this country and causes more loss of life and property than all natural disasters combined. Small towns and rural areas reported a greater frequency of fires with higher death rates and dollar losses per capita than larger cities and metropolitan areas. As more people move into small towns and rural areas, provision of adequate fire protection services becomes even more important. The following information can assist local decision makers in planning new or additional fire services.Reviewed October 1993

Collider-independent t tbar forward-backward asymmetries

We introduce the forward-backward asymmetries A_u, A_d corresponding to u ubar, d dbar -> t tbar production, respectively, at hadron colliders. These are collider- and center-of-mass-independent observables, directly related to the forward-backward and charge asymmetries measured at the Tevatron and the LHC, respectively. We discuss how to extract these asymmetries from data. Because these asymmetries are collider-independent, their measurement at these two colliders could elucidate the nature of the anomalous forward-backward asymmetry measured at the Tevatron. Our framework also shows in a model-independent fashion that a positive Tevatron asymmetry exceeding the standard model expectation is compatible with the small asymmetry measured at the LHC.Comment: RevTeX 5 pages. Extended discussion about A_FB vs A_C, several clarifications, references added. Version to appear in PR

Lactose and benign ovarian tumours in a case–control study

We investigated the relation between benign ovarian tumours and lactose among 746 case women identified at seven New York metropolitan hospitals and 404 community controls, age and hospital frequency matched to the expected case distribution. No increase in risk was found for lactose (highest quartile versus lowest: adjusted odds ratio = 0.82 (95% CI 0.57–1.20) or for any other lactose foods. © 2000 Cancer Research Campaign http://www.bjcancer.co

Surveilling the web, mobile, and language accessibility of Communication’s digital presence within institutions of higher education globally

This study aims to understand the general web accessibility of digital information networks which may serve as barriers for access to the global discipline of Communication through institutional and departmental websites, specifically for persons with disabilities and those with limited English proficiency (LEP). Our exploratory content analysis relies on computer-aided software to systematically analyze the departmental home pages of websites of institutional members of the International Communication Association (ICA), N = 77, representing 26 countries, globally. Findings from this study help us to: (1) better understand the general web, language, and mobile accessibility of discipline-related online information; (2) identify strengths and opportunities for improvement; and, (3) to reflect upon the anticipated barriers impacting persons with disabilities when accessing higher education information online

Dose-finding study of a 90-day contraceptive vaginal ring releasing estradiol and segesterone acetate.

ObjectiveTo evaluate serum estradiol (E2) concentrations during use of 90-day contraceptive vaginal rings releasing E2 75, 100, or 200 mcg/day and segesterone acetate (SA) 200 mcg/day to identify a dose that avoids hypoestrogenism.Study designWe conducted a multicenter dose-finding study in healthy, reproductive-aged women with regular cycles with sequential enrollment to increasing E2 dose groups. We evaluated serum E2 concentrations twice weekly for the primary outcome of median E2 concentrations throughout initial 30-day use (target ≥40 pg/mL). In an optional 2-cycle extension substudy, we randomized participants to 2- or 4-day ring-free intervals per 30-day cycle to evaluate bleeding and spotting based on daily diary information.ResultsSixty-five participants enrolled in E2 75 (n = 22), 100 (n = 21), and 200 (n = 22) mcg/day groups; 35 participated in the substudy. Median serum E2 concentrations in 75 and 100 mcg/day groups were <40 pg/mL. In the 200 mcg/day group, median E2 concentrations peaked on days 4-5 of CVR use at 194 pg/mL (range 114-312 pg/mL) and remained >40 pg/mL throughout 30 days; E2 concentrations were 37 pg/mL (range 28-62 pg/mL) on days 88-90 (n = 11). Among the E2 200 mcg/day substudy participants, all had withdrawal bleeding following ring removal. The 2-day ring-free interval group reported zero median unscheduled bleeding and two (range 0-16) and three (range 0-19) unscheduled spotting days in extension cycles 1 and 2, respectively. The 4-day ring-free interval group reported zero median unscheduled bleeding or spotting days.ConclusionsEstradiol concentrations with rings releasing E2 200 mcg/day and SA 200 mcg/day avoid hypoestrogenism over 30-day use.ImplicationsA 90-day contraceptive vaginal ring releasing estradiol 200 mcg/day and segesterone acetate 200 mcg/day achieves estradiol concentrations that should avoid hypoestrogenism and effectively suppresses ovulation