Ionic liquids at electrified interfaces

Until recently, “room-temperature” (<100–150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)–(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of “first-generation” room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the “later generation” RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in “cocktails” of one’s choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost “universal” solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) “sister-systems”.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules

Regional Myocutaneous Flaps for Head and Neck Reconstruction: Experience of a Head and Neck Cancer Unit

Background: Pectoralis major myocutaneous pedicle flap and other regional myocutaneous pedicle flaps (RMF), despite the superiority shown by free flaps, have remained relevant in the reconstruction of major head and neck oncologic defects. It has continued to find relevance as the preferred reconstruction of choice in some general head and neck reconstructive applications. While its role has been defined in developed environment, the same cannot be said for developing environment. The aim thus, was to review our experiences with RMFs in head and neck reconstructions, with a view to evaluating the indications and outcomes in a limited opportunity environment with some free flaps expertise.Materials and Methods: This was a retrospective cohort study from records of RMF cases performed for head and neck reconstruction, at the study institution. Eligibility for study inclusion comprised case cohorts with advanced head and neck diseases requiring ablative surgery and reconstruction with pectoralis major flaps and other RMFs.Results: A total of 17 cases were treated with RMFs. 10 were pectoralis major flaps while 7 were other RMFs. The main indications were failed free flaps and financial constraints. No regional pedicle flap failure was recorded; however, complication rate was 35.5% (6/17).Conclusion: Pectoralis major flaps and other RMFs were very reliable option for head and neck reconstruction. Free flap failure and financial constraints were the main indications for RMF reconstruction indications in head and neck reconstruction in a developing environment with some free flap expertise.Keywords: Free flap, myocutaneous, pectoralis, reconstructio

Emerging Trends in the Epidemiological Pattern of Head and Neck Cancers in Lagos, Nigeria

Background: Unfortunately, despite an increase in medical knowledge, survival rates of head and neck cancers (HNCs) have not been observed to improve greatly. This is true, especially in tumors located in obscure primary sites or late presentation. Aim: The purpose of this study is to assess the epidemiologic pattern of HNCs and to evaluate its emerging trends and patterns in Lagos state. Subjects and Methods: A retrospective study was conducted from 2003 to 2013 that analyzed histologically diagnosed cases of HNC at the Pathology Departments of  he two tertiary teaching hospitals in Lagos. Data analysis was performed using the Statistical Package for the Social Sciences (version 20) statistical software. Results: One thousand and eighty‑three cases of head and neck malignancies were recorded. A female: male ratio of 1.01:1 was reported with mean age of 39.6 (standard deviation 21.1) years. The oral cavity was the most affected anatomic site (21.2%, 230/1083) in the period under review. Malignant epithelial tumors accounted for 72% (779/1083) of cases seen. Carcinomas were the most common histological variant seen (67%, 726/1083) and squamous cell carcinoma accounted for 58% (421/726) of carcinomas recorded. Oral cavity malignancies (21.8%, 118/540) were the most common in males while thyroid malignancies (28.5%, 155/543) were the most seen in females. In children (≤15 years), the most common histologic findings were carcinomas (42.3%; 77/182) and retinoblastomas (23.6%; 43/182). Conclusion: Epithelial malignancies were the most common malignancy in the study, and the oral cavity appears to be the increasingly predominant site for HNCs. A changing pattern in gender predominance, age distribution, and frequency with  histological variants and anatomical sites was also observed in this study.Keywords: Epidemiology, Head and neck cancer, Prevalenc

Maxillary reconstruction with radial forearm fasciocutaneous free flap: a case presentation

No Abstrac

Unusual Voltammetry of the Reduction of O2 in [C4dmim][N(Tf)2] Reveals a Strong Interaction of O2•− with the [C4dmim]+ Cation

Voltammetric studies of the reduction of oxygen in the room temperature ionic liquid [C4dmim][N(Tf)2] have revealed a significant positive shift in the back peak potential, relative to that expected for a simple electron transfer. This shift is thought to be due to the strong association of the electrogenerated superoxide anion with the solvent cation. In this work we quantitatively simulate the microdisc electrode voltammetry using a model based upon a one-electron reduction followed by a reversible chemical step, involving the formation of the [C4dmim]+···O2•- ion-pair, and in doing so we extract a set of parameters completely describing the system. We have simulated the voltammetry in the absence of a following chemical step and have shown that it is impossible to simultaneously fit both the forward and reverse peaks. To further support the parameters extracted from fitting the experimental voltammetry, we have used these parameters to independently simulate the double step chronoamperometric response and found excellent agreement. The parameters used to describe the association of the O2•- with the [C4dmim]+ were kf = 1.4 × 103 s-1 for the first-order rate constant and Keq = 25 for the equilibrium constant

The Reduction of Oxygen in Various Room Temperature Ionic Liquids in the Temperature Range 293-318 K: Exploring the Applicability of the Stokes-Einstein Relationship in Room Temperature Ionic Liquids

The voltammetry for the reduction of oxygen at a microdisk electrode is reported in six commonly used RTILs: [C(4)mim][NTf(2)], [C(4)mpyrr][NTf(2)], [C(4)dmim][NTf(2)], [C(4)mim][BF(4)], [C(4)mim][PF(6)], and [N(6,2,2,2)][NTf(2)], where [C(4)mim](+) is 1-butyl-3-methylimidazolium, [NTf(2)](-) is bis(trifluoromethanesulfonyl)imide, [C(4)mpyrr](+) is N-butyl-N-methylpyrrolidinium, [C(4)dmim](+) is 1-butyl-2,3-methylimidazolium, [BF(4)](-) is tetrafluoroborate, [PF(6)](-) is hexafluorophosphate, and [N(6,2,2,2)](+) is n-hexyltriethylammonium at varying scan rates (50-4000 mV s(-1)) and temperatures (293-318 K). Diffusion coefficients, D, of oxygen are deduced at each temperature from potential-step chronoamperometry, and diffusional activation energies are calculated. Oxygen solubilities are also reported as a function of temperature. In the six ionic liquids, the Stokes-Einstein relationship (D proportional, variant eta(-1)) was found to apply only very approximately for oxygen. This is considered in relationship to the behavior of other diverse solutes in RTILs

Physical Properties of a New Deep Eutectic Solvent Based on a Sulfonium Ionic Liquid as a Suitable Electrolyte for Electric Double-Layer Capacitors

International audienceWe present in this study the physical properties of two deep eutectic solvent (DES) mixtures based on solid sulfonium bis[(trifluoromethyl)sulfonyl]imide (S111TFSI) aprotic ionic liquid and two different H-bond donors, formamide (FMD) and trifluoroamide (TFA), according to temperature. First, we investigated their thermal properties by differential scanning calorimetry , and the results revealed the formation of a deep eutectic solvent giving a wide liquid range from −40 to 270 °C for these mixtures which froze at a much lower temperature than either of the individual components. The densities, ionic conductivities, and viscosities of these DESs were measured according to temperature and then discussed by applying Arrhenius or Vogel–Tamman–Fulcher (VTF) equations, as well as the Walden classification. Thanks to their favorable transport properties, both S111TFSI/TFA and S111TFSI/FMD mixtures contribute to the formulation of the electrolytes with 1 mol·L–1 LiTFSI. The performances of these electrolytes were then estimated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge for activated carbon electrochemical double layer capacitor applications at 80 °C. The results showed that the selected H-bond donors allowed ion dissociation without solvation, increasing micropore accessibility and giving high capacitance values up to 350 F·g–1 in the case of formamide-based DESs. These unusual performances of the activated carbon material are debated with regards to the activation energy barrier to access the microporosity by ions in sulfonium-amides DESs