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We report a patient with recurrent discharging sinus over the nasal bridge which was finally diagnosed as pilonidal sinus over the nasal bridge. Nasal pilonidal sinus is a rare condition that presents as a chronic and recurrent inflammation of the hair follicles and surrounding tissues of the nose, leading to the formation of abscesses and sinus tracts. The following report deals the dilemma of diagnosing and management of the patient. Though rare, nasal pilonidal sinus should be included as a differential diagnosis to aid in management as well as to improve awareness and inclusion of this condition. This report provides an overview of the clinical presentation, diagnosis and management of nasal pilonidal sinus. [ABSTRACT FROM AUTHOR]

The nanostructure of engineered bioscaffolds has a profound impact on cell response, yet its understanding remains incomplete as cells interact with a highly complex interfacial layer rather than the material itself. For bioactive glass scaffolds, this layer comprises of silica gel, hydroxyapatite (HA)/carbonated hydroxyapatite (CHA), and absorbed proteins—all in varying micro/nano structure, composition, and concentration. Here, we examined the response of MC3T3-E1 pre-osteoblast cells to 30 mol% CaO–70 mol% SiO2 porous bioactive glass monoliths that differed only in nanopore size (6–44 nm) yet resulted in the formation of HA/CHA layers with significantly different microstructures. We report that cell response, as quantified by cell attachment and morphology, does not correlate with nanopore size, nor HA/CHO layer micro/nano morphology, or absorbed protein amount (bovine serum albumin, BSA), but with BSA's secondary conformation as indicated by its β-sheet/α-helix ratio. Our results suggest that the β-sheet structure in BSA interacts electrostatically with the HA/CHA interfacial layer and activates the RGD sequence of absorbed adhesion proteins, such as fibronectin and vitronectin, thus significantly enhancing the attachment of cells. These findings provide new insight into the interaction of cells with the scaffolds' interfacial layer, which is vital for the continued development of engineered tissue scaffolds. [ABSTRACT FROM AUTHOR]

Fabrication of single crystals of materials by conventional methods, which decompose or undergo incongruent melting upon melting, has limited the development of advanced technologies. A solution to this challenge was demonstrated a few years ago using laser heating in a localized region to minimize undesirable nucleation, and then scanning the beam to obtain single crystal growth at the crystallization temperature of glass that was usually significantly below its melting temperature. An overview of the development of this new mode of crystal growth including some new results and insights is presented here. The discovery of rotating lattice single crystal as a novel form of meta-material and its characteristics in relation to process parameters are discussed in detail. Preliminary observations suggest strong correlation between the shape of growth front and rate of lattice rotation. Finally, challenges to single crystal growth via solid → solid transformation are exposed, which include the high interfacial stresses from density difference and the thermal expansion mismatch, of extremely steep T gradients due to highly localized (~μm) laser heating, and of the preferential diffusion of certain elements in the case of incongruent crystallization. [ABSTRACT FROM AUTHOR]

Ferroelectric single-crystal-architecture-in-glass is a new class of metamaterials that would enable active integrated optics if the ferroelectric behavior is preserved within the confines of glass. We demonstrate using lithium niobate crystals fabricated in lithium niobosilicate glass by femtosecond laser irradiation that not only such behavior is preserved, the ferroelectric domains can be engineered with a DC bias. A piezoresponse force microscope is used to characterize the piezoelectric and ferroelectric behavior. The piezoresponse correlates with the orientation of the crystal lattice as expected for unconfined crystal, and a complex micro- and nano-scale ferroelectric domain structure of the as-grown crystals is revealed. [ABSTRACT FROM AUTHOR]

We analyzed the biological performance of spinodally and droplet-type phase-separated 45S5 Bioglass generated by quenching the melt from different equilibrium temperatures. MC3T3-E1 pre-osteoblast cells attached more efficiently to 45S5 Bioglass® with spinodal than to the one with droplet morphology, providing the first demonstration of the role of micro-/nano-scale on the bioactivity of Bioglass®. Upon exposure to biological solutions, phosphate buffered saline (PBS) and cell culture medium (α-MEM), a layer of hydroxyapatite (HA) formed on both glass morphologies. Although both Bioglass® varieties were incubated under identical conditions, and physico-chemical characteristics of the HA layers were similar, the adsorption magnitude of a model protein, bovine serum albumin (BSA, an abundant blood serum component) and its β-sheet/β-turn ratio and α-helix content were significantly higher on spinodal than droplet type Bioglass®. These results indicate that: (i) a protein layer quickly adsorbs on the surface of 45S5 Bioglass® varieties (with or without HA layer), (ii) the amount and the conformation of adsorbed proteins are guided by the glass micro-/nano-structure, and (iii) cell attachment and proliferation are influenced by the concentration and the conformation of attached proteins with a significantly better cell adhesion to spinodal type 45S5 Bioglass® substrate. Taken together, our results indicate that the biological performance of 45S5 Bioglass® can be improved further with a relatively simple, inexpensive fabrication procedure that provides a superior glass micro-/nano-structure. Graphical abstract: A simple modification to the fabrication procedure of classic 45S5 Bioglass® generates spinodal (A(a)) and droplet (A(b)) varieties and has a significant impact on protein adsorption (B) and cell adhesion (C). [ABSTRACT FROM AUTHOR]

Letter to the Editor [ABSTRACT FROM AUTHOR]

In 1991, Arthur Stanley Nowick and his co-workers discovered a new universality, now known as nearly constant loss (NCL) or second universality. This mini-review, written in honor of A.S. Nowick, reports on the present authors' more recent endeavors and advances on their way toward understanding the second-universality phenomenon. In pursuit of that goal, new ideas and new data have led us to new questions and new answers. The essence of the new ideas was to consider time-dependent single-particle potentials, caused by Coulomb interactions and experienced by locally mobile ions. The dynamics of such ions were described in terms of a rate equation, and model conductivity spectra showing the NCL effect could be derived from it, with the help of linear response theory. New data corroborated the predictions made by the model. Also, our experimental data suggested a gradual transition, occurring with decreasing temperature, from a slightly activated NCL-type behavior to the non-activated features of the second universality. Two new questions have emerged. (i) Is it possible to quantify the transition mentioned above? (ii) Is there a crossover of the low-temperature, second-universality ionic conductivity from its characteristic linear frequency dependence to a quadratic one at low frequencies? New answers to our two questions can now be given, both of them in the affirmative. In particular, the crossover in the frequency dependence has been identified as an implication of the localization of the non-activated ionic motion. [ABSTRACT FROM AUTHOR]

Since Roman times the addition of tin is known to induce a deep red color in ruby glass based on gold nanoparticles, but very little information is available on how electrical properties of such glasses are affected by the presence of gold nanoparticles or tin doping. Therefore, we have explored the electrical effects of the addition of tin (≤0.1 mol%) to sodium trisilicate glass, which was doped with 0.1 mol% gold. The addition of both 0.1 mol% gold and 0.1 mol% tin increases the DC electrical conductivity, which arises from sodium ion transport, compared to base glass. The activation energy of DC conductivity decreases when the amount of tin increases with the gold content held constant. The mechanism of the enhancement of Na ion transport appears to be different for the two types of dopings: Au doping causes general expansion of molar volume whereas tin doping enhances the polarizability of the medium. [ABSTRACT FROM AUTHOR]

Positron annihilation lifetime measurements are performed for sol–gel-derived 70 mol% SiO2–30 mol% CaO bioactive glass. Strong positronium formation processes are shown to be an inherent feature for these kinds of materials. Observed orthopositronium (o-Ps) lifetimes show a three-modal distribution with lifetime values weighed at ∼2, ∼18, and ∼70 ns. The exposure of the investigated sol–gel-derived bioactive glasses to water vapor significantly modifies o-Ps lifetime distribution due to the penetration of water molecules into the nanopores, indicating high ratio of their interconnectivity. Classic Tao–Eldrup equation is used to relate the o-Ps lifetimes with the size of nanopores, whose distribution is verified by nitrogen adsorption porosimetry. [ABSTRACT FROM AUTHOR]

According to Joule's well-known first law, application of electric field across a homogeneous solid should produce heat uniformly in proportion to the square of electrical current. Here we report strong departure from this expectation for common, homogeneous ionic solids such as alkali silicate glasses when subjected even to moderate fields (~100 V/cm). Unlike electronically conducting metals and semiconductors, with time the heating of ionically conducting glass becomes extremely inhomogeneous with the formation of a nanoscale alkali-depletion region, such that the glass melts near the anode, even evaporates, while remaining solid elsewhere. In situ infrared imaging shows and finite element analysis confirms localized temperatures more than thousand degrees above the remaining sample depending on whether the field is DC or AC. These observations unravel the origin of recently discovered electric field induced softening of glass. The observed highly inhomogeneous temperature profile point to the challenges for the application of Joule's law to the electrical performance of glassy thin films, nanoscale devices, and similarly-scaled phenomena. [ABSTRACT FROM AUTHOR]

Lithium niobate crystals were grown in 3D through localized heating by femtosecond laser irradiation deep inside 35Li2O-35Nb2O5-30SiO2 glass. Laser scanning speed and power density were systematically varied to control the crystal growth process and determine the optimal conditions for the formation of single crystal lines. EBSD measurements showed that, in principle, single crystals can be grown to unlimited lengths using optimal parameters. We successfully tuned the parameters to a growth mode where nucleation and growth occur upon heating and ahead of the scanning laser focus. This growth mode eliminates the problem reported in previous works of non-uniform polycrystallinity because of a separate growth mode where crystallization occurs during cooling behind the scanning laser focus. To our knowledge, this is the first report of such a growth mode using a fs laser. The crystal cross-sections possessed a symmetric, smooth lattice misorientation with respect to the c-axis orientation in the center of the crystal. Calculations indicate the observed misorientation leads to a decrease in the refractive index of the crystal line from the center moving outwards, opening the possibility to produce within glass a graded refractive index single crystal (GRISC) optically active waveguide. [ABSTRACT FROM AUTHOR]

Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64 dB/cm at 1530 nm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing. [ABSTRACT FROM AUTHOR]