The Effect of Resin Bonding on Long-Term Success of High-Strength Ceramics

Digital manufacturing, all-ceramics, and adhesive dentistry are currently the trendiest topics in clinical restorative dentistry. Tooth- and implant-supported fixed restorations from computer-aided design (CAD)/computer-aided manufacturing (CAM)–fabricated high-strength ceramics—namely, alumina and zirconia—are widely accepted as reliable alternatives to traditional metal-ceramic restorations. Most recent developments have focused on high-translucent monolithic full-contour zirconia restorations, which have become extremely popular in a short period of time, due to physical strength, CAD/CAM fabrication, and low cost. However, questions about proper resin bonding protocols have emerged, as they are critical for clinical success of brittle ceramics and treatment options that rely on adhesive bonds, specifically resin-bonded fixed dental prostheses or partial-coverage restorations such as inlays/onlays and veneers. Resin bonding has long been the gold standard for retention and reinforcement of low- to medium-strength silica-based ceramics but requires multiple pretreatment steps of the bonding surfaces, increasing complexity, and technique sensitivity compared to conventional cementation. Here, we critically review and discuss the evidence on resin bonding related to long-term clinical outcomes of tooth- and implant-supported high-strength ceramic restorations. Based on a targeted literature search, clinical long-term studies indicate that porcelain-veneered alumina or zirconia full-coverage crowns and fixed dental prostheses have high long-term survival rates when inserted with conventional cements. However, most of the selected studies recommend resin bonding and suggest even greater success with composite resins or self-adhesive resin cements, especially for implant-supported restorations. High-strength ceramic resin-bonded fixed dental prostheses have high long-term clinical success rates, especially when designed as a cantilever with only 1 retainer. Proper pretreatment of the bonding surfaces and application of primers or composite resins that contain special adhesive monomers are necessary. To date, there are no clinical long-term data on resin bonding of partial-coverage high-strength ceramic or monolithic zirconia restorations. © 2017, © International & American Associations for Dental Research 2017

Borderline Aggregation Kinetics in ``Dry'' and ``Wet'' Environments

We investigate the kinetics of constant-kernel aggregation which is augmented by either: (a) evaporation of monomers from finite-mass clusters, or (b) continuous cluster growth -- \ie, condensation. The rate equations for these two processes are analyzed using both exact and asymptotic methods. In aggregation-evaporation, if the evaporation is mass conserving, \ie, the monomers which evaporate remain in the system and continue to be reactive, the competition between evaporation and aggregation leads to several asymptotic outcomes. For weak evaporation, the kinetics is similar to that of aggregation with no evaporation, while equilibrium is quickly reached in the opposite case. At a critical evaporation rate, the cluster mass distribution decays as $k^{-5/2}$, where $k$ is the mass, while the typical cluster mass grows with time as $t^{2/3}$. In aggregation-condensation, we consider the process with a growth rate for clusters of mass $k$, $L_k$, which is: (i) independent of $k$, (ii) proportional to $k$, and (iii) proportional to $k^\mu$, with $0<\mu<1$. In the first case, the mass distribution attains a conventional scaling form, but with the typical cluster mass growing as $t\ln t$. When $L_k\propto k$, the typical mass grows exponentially in time, while the mass distribution again scales. In the intermediate case of $L_k\propto k^\mu$, scaling generally applies, with the typical mass growing as $t^{1/(1-\mu)}$. We also give an exact solution for the linear growth model, $L_k\propto k$, in one dimension.Comment: plain TeX, 17 pages, no figures, macro file prepende

Maxwell Model of Traffic Flows

We investigate traffic flows using the kinetic Boltzmann equations with a Maxwell collision integral. This approach allows analytical determination of the transient behavior and the size distributions. The relaxation of the car and cluster velocity distributions towards steady state is characterized by a wide range of velocity dependent relaxation scales, $R^{1/2}<\tau(v)<R$, with $R$ the ratio of the passing and the collision rates. Furthermore, these relaxation time scales decrease with the velocity, with the smallest scale corresponding to the decay of the overall density. The steady state cluster size distribution follows an unusual scaling form $P_m \sim ^{-4} \Psi(m/< m>^2)$. This distribution is primarily algebraic, $P_m\sim m^{-3/2}$, for $m\ll ^2$, and is exponential otherwise.Comment: revtex, 10 page

Development of a New Clusterization Method for the GEM-TPC Detector

The Facility for Antiproton and Ion Research FAIR, in Darmstadt Germany, will be one of the largest accelerator laboratories worldwide. The Superconducting FRagment Separator (Super-FRS)* is one of its main components. The Super-FRS can produce, separate and deliver high-energy radioactive beams with intensities up to 1e11 ions/s, covering projectiles from protons up to uranium and it can be used as an independent experimental device. The Gas Electron Multiplier-based Time Projection Chambers (GEM-TPC) in twin configuration is a newly developed beam tracking detector capable of providing spatial resolution of less than 1 mm with a tracking efficiency close to 100% at 1 MHz counting rate. The GEM-TPC (HGB4) was tested at the FRagment Separator (FRS), with 238U beam at 850 MeV/u. A new clusterization method was developed, for the first time and used for an analysis. This method allowed to access to waveforms of each strip signal within a single trigger in an event-by-event basis. The procedures involved in this method will be shown in details.Peer reviewe

Severe course of Lyme neuroborreliosis in an HIV-1 positive patient; case report and review of the literature

<p>Abstract</p> <p>Background</p> <p>Lyme Neuroborreliosis (LNB) in a human immunodeficiency virus (HIV) positive patient is a rare co-infection and has only been reported four times in literature. No case of an HIV patient with a meningoencephalitis due to LNB in combination with HIV has been described to date.</p> <p>Case presentation</p> <p>A 51 year old woman previously diagnosed with HIV presented with an atypical and severe LNB. Diagnosis was made evident by several microbiological techniques. Biochemical and microbiological recovery during treatment was rapid, however after treatment the patient suffered from severe and persistent sequelae.</p> <p>Conclusions</p> <p>A clinician should consider LNB when being confronted with an HIV patient with focal encephalitis, without any history of Lyme disease or tick bites, in an endemic area. Rapid diagnosis and treatment is necessary in order to minimize severe sequelae.</p

Nonlinear drift-diffusion model of gating in the fast Cl channel

The dynamics of the open or closed state region of an ion channel may be described by a probability density p(x,t) which satisfies a Fokker-Planck equation. The closed state dwell-time distribution fc(t) derived from the Fokker-Planck equation with a nonlinear diffusion coefficient D(x)∝exp(−γx), γ>0 and a linear ramp potential Uc(x), is in good agreement with experimental data and it may be shown analytically that if γ is sufficiently large, fc(t)∝t−2−ν for intermediate times, where ν=Uc′∕γ≈−0.3 for a fast Cl channel. The solution of a master equation which approximates the Fokker-Planck equation exhibits an oscillation superimposed on the power law trend and can account for an empirical rate-amplitude correlation that applies to several ion channels.S. R. Vaccar

MscS-like mechanosensitive channels in plants and microbes

The challenge of osmotic stress is something all living organisms must face as a result of environmental dynamics. Over the past three decades, innovative research and cooperation across disciplines have irrefutably established that cells utilize mechanically gated ion channels to release osmolytes and prevent cell lysis during hypoosmotic stress. Early electrophysiological analysis of the inner membrane of Escherichia coli identified the presence of three distinct mechanosensitive activities. The subsequent discoveries of the genes responsible for two of these activities, the mechanosensitive channels of large (MscL) and small (MscS) conductance, led to the identification of two diverse families of mechanosensitive channels. The latter of these two families, the MscS family, consists of members from bacteria, archaea, fungi, and plants. Genetic and electrophysiological analysis of these family members has provided insight into how organisms use mechanosensitive channels for osmotic regulation in response to changing environmental and developmental circumstances. Furthermore, determining the crystal structure of E. coli MscS and several homologues in several conformational states has contributed to our understanding of the gating mechanisms of these channels. Here we summarize our current knowledge of MscS homologues from all three domains of life and address their structure, proposed physiological functions, electrophysiological behaviors, and topological diversity

A Folding Pathway-Dependent Score to Recognize Membrane Proteins

While various approaches exist to study protein localization, it is still a challenge to predict where proteins localize. Here, we consider a mechanistic viewpoint for membrane localization. Taking into account the steps for the folding pathway of α-helical membrane proteins and relating biophysical parameters to each of these steps, we create a score capable of predicting the propensity for membrane localization and call it FP3mem. This score is driven from the principal component analysis (PCA) of the biophysical parameters related to membrane localization. FP3mem allows us to rationalize the colocalization of a number of channel proteins with the Cav1.2 channel by their fewer propensities for membrane localization

ATP release via anion channels

ATP serves not only as an energy source for all cell types but as an ‘extracellular messenger-for autocrine and paracrine signalling. It is released from the cell via several different purinergic signal efflux pathways. ATP and its Mg2+ and/or H+ salts exist in anionic forms at physiological pH and may exit cells via some anion channel if the pore physically permits this. In this review we survey experimental data providing evidence for and against the release of ATP through anion channels. CFTR has long been considered a probable pathway for ATP release in airway epithelium and other types of cells expressing this protein, although non-CFTR ATP currents have also been observed. Volume-sensitive outwardly rectifying (VSOR) chloride channels are found in virtually all cell types and can physically accommodate or even permeate ATP4- in certain experimental conditions. However, pharmacological studies are controversial and argue against the actual involvement of the VSOR channel in significant release of ATP. A large-conductance anion channel whose open probability exhibits a bell-shaped voltage dependence is also ubiquitously expressed and represents a putative pathway for ATP release. This channel, called a maxi-anion channel, has a wide nanoscopic pore suitable for nucleotide transport and possesses an ATP-binding site in the middle of the pore lumen to facilitate the passage of the nucleotide. The maxi-anion channel conducts ATP and displays a pharmacological profile similar to that of ATP release in response to osmotic, ischemic, hypoxic and salt stresses. The relation of some other channels and transporters to the regulated release of ATP is also discussed