Defining Dry Eye from a Clinical Perspective

Over the past decades, the number of patients with dry eye disease (DED) has increased dramatically. The incidence of DED is higher in Asia than in Europe and North America, suggesting the involvement of cultural or racial factors in DED etiology. Although many definitions of DED have been used, discrepancies exist between the various definitions of dry eye disease (DED) used across the globe. This article presents a clinical consensus on the definition of DED, as formulated in four meetings with global DED experts. The proposed new definition is as follows: “Dry eye is a multifactorial disease characterized by a persistently unstable and/or deficient tear film (TF) causing discomfort and/or visual impairment, accompanied by variable degrees of ocular surface epitheliopathy, inflammation and neurosensory abnormalities.” The key criteria for the diagnosis of DED are unstable TF, inflammation, ocular discomfort and visual impairment. This definition also recommends the assessment of ocular surface epitheliopathy and neurosensory abnormalities in each patient with suspected DED. It is easily applicable in clinical practice and should help practitioners diagnose DED consistently. This consensus definition of DED should also help to guide research and clinical trials that, to date, have been hampered by the lack of an established surrogate endpoint.     

Data Driven Order Selection for Projection Estimator of the Spectral Density of Time Series with Long Range Dependence

Fractional exponential (FEXP) models have been introduced by Robinson (1991) and Beran (1993) to model the spectral density of a covariance stationary long-range dependent process. In this class of models, the spectral density f ( x ) of the process is decomposed as f ( x ) = |1 − exp( ix )|^{−2 d} f _*( x ), where f _*( x ) accounts for the short-memory component. In this contribution, FEXP models are used to construct semi-parametric estimates of the fractional differencing coefficient and of the spectral density, by considering an infinite Fourier series expansion of log f _*( x ). A data-driven order selection procedure, adapted from the Mallows' C _p procedure, is proposed to determine the order of truncation. The optimality of the data-driven procedure is established, under mild assumptions on the short-memory component f _*( x ). A limited Monte-Carlo experiment is presented to support our claims.     

Calcium silicate hydrate—in-situ development of the silicate structure followed by infrared spectroscopy

In the current study, the development of the silicate structure of synthetic calcium silicate hydrates with different calcium contents was followed by in-situ infrared (IR) spectroscopy and correlated to the in-situ phase development evaluated by X-ray diffraction (XRD). A baseline correction method initially developed for X-ray diffractograms was successfully adapted for the complex background of the fingerprint region in in-situ IR, which significantly contributed to signal quality and reproducibility. The development of separate silicate infrared bands could be monitored over 24 h of reaction. These bands could be assigned to oligomeric and dimeric species based on their time and stoichiometry-dependent development. It was clearly shown that the main peak of the dimeric silicate species was overlooked in the literature. The correlation of time-dependent events to in-situ XRD revealed that changes in the unit cell of calcium silicate hydrate are related to silicate polymerization. The results were compared to ²⁹Si-MAS-NMR, which highlighted the benefits of in-situ IR spectroscopy.     

Stress Heterogeneity Effect on the Strength of Silicon Nitride

The experiments reported in this paper demonstrate the causes of the failure of monolithic ceramics. The specimens are made of silicon nitride and tested at room temperature. The stress field within the specimen is different for each of four series of tests that have been conducted. Fractographic observations have also been made to identify the causes of the failures. A size effect analysis is performed.     

Inactivation of Escherichia coli, Listeria innocua and Saccharomyces cerevisiae in relation to membrane permeabilization and subsequent leakage of intracellular compounds due to pulsed electric field processing

Membrane permeabilization, caused by pulsed electric field (PEF) processing of microbial cells, was investigated by measurement of propidium iodide (PI) uptake with flow cytometry. Inactivation of Escherichia coli, Listeria innocua and Saccharomyces cerevisiae was determined by viable counts, and leakage of intracellular compounds, such as ATP and UV-absorbing substances, was measured in the extracellular environment. Electrical field strength and pulse duration influenced membrane permeabilization of all three tested organisms of which S. cerevisiae was the most PEF sensitive, followed by E. coli and L. innocua. It was shown by viable counts, PI uptake and leakage of intracellular compounds that L. innocua was the most resistant. Increased inactivation corresponded to greater numbers of permeabilized cells, which were reflected by increased PI uptake and larger amounts of intracellular compounds leaking from cells. For E. coli and L. innocua, a linear relationship was observed between the number of inactivated cells (determined as CFU) and cells with permeated membranes (determined by PI uptake), with higher number of inactivated cells than permeated cells. Increased leakage of intracellular compounds with increasing treatment severity provided further evidence that cells were permeabilized. For S. cerevisiae, there was higher PI uptake after PEF treatments, although very little or no inactivation was observed. Results suggest that E. coli and L. innocua cells, which took up PI, lost their ability to multiply, whereas cells of S. cerevisiae, which also took up PI, were not necessarily lethally permeabilized.     

Stability of rare‐earth‐doped spherical yttria‐stabilized zirconia synthesized by ultrasonic spray pyrolysis

Phase stability is one of the crucial requirements for any material that can be used at elevated temperature applications such as thermal barrier coating (TBC). The most traditional TBC material, partially stabilized zirconia, limits the operating temperature due to its phase transformation. Conversely, the low thermal conductivity of fully stabilized zirconia (YSZ) may enable effective reduction in the surface temperature on the coated component, while avoiding deleterious phase transitions, although still being subjected to sintering and grain growth. It has been reported that addition of rare‐earths as dopants to YSZ can significantly increase resistance to grain growth at high temperature. Keeping this under consideration, this work investigates the role of rare‐earths (lanthanum and gadolinium) in increasing thermal stability of YSZ microspheres, the building blocks for high‐temperature photonics for reflective TBC. The spheres were produced by ultrasonic spray pyrolysis, and the doping led to significant improvement of stability by significant inhibition of grain growth. While the individual dopants showed significant growth and sintering inhibition up to 900°C, co‐doping with 4% (in mol) of each (Gd and La) led to coarsening resistance up to 1000°C for 3 hours, when particles retained reasonable spherical features with nanometric crystallite sizes.     

Synergistic effect of organoclay fillers based on fluorinated surfmers for preparation of polystyrene nanocomposites

Novel fluorinated reactive surfactants were used for the organic modification of monmorillonite clays. These organoclays were used for the preparation of polystyrene?clay nanocomposites by in‐situ free radical polymerization. Reference systems based on hydrocarbon homologous surfmer and nonpolymerizable surfactants were also used to deduce the effect of the fluorine moiety and the polymerizable function on the morphology and thermal stability of the prepared nanocomposites. Different structural parameters of the surfactants were investigated and modulated for the clay modification including: the nature of surfactant (surfmer/classical surfactant, fluorinated, or hydrocarbonated), the length of the fluorinated chain as well as the length of the hydrocarbon spacers linking the ammonium head to the fluorine chain or the polymerizable acrylic function. Wide angle‐X‐ray scattering (WAXD), thermogravimetric analysis (TGA), and electronic microcopies (TEM and SEM) were used to establish a structure‐morphology, thermal properties relationships, and to highlight the key parameters governing the exfoliation process. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42347.