This study determined the changes of calcium concentration in a medium containing teeth/biofilm exposed to Coffea canephora extract (CCE). Enamel fragments were randomly fixed into two 24‐well ...polystyrene plates containing BHI. Pooled human saliva was added to form biofilm on fragments. Specimens were divided into treatment groups (G, n = 8 per group) and treated with 50 μl daily for 1 min per week, as follows: G1, 20% CCE; G2, Milli‐Q water (negative control); G3, antibiotic (positive control). Six fragments represented the blank control (G4). The calcium content was observed at baseline, 4 and 7 days of treatment by atomic‐absorption spectrophotometry. Cross‐sectional hardness of enamel was a demineralization indicator. Calcium increased in the medium after 4 and 7 days of treatment in G1 (3·80 ± 1·3 mg l⁻¹ and 4·93 ± 2·1 mg l⁻¹, respectively) and G3 (4th day = 5·7 ± 1·8 mg l⁻¹; 7th day = 6·7 ± 3·5 mg l⁻¹) (P > 0·05). Calcium from G2 decreased after 7 days, which was different from G3 (P < 0·05). The lower calcium content, at the end of the experiment, was represented by G4, 2·16 ± 0·2 mg l⁻¹. The increase in calcium after treatment with CCE is probably due to its antibacterial effect, which caused the bacterial lysis and consequent release of calcium in the medium. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed an inhibitory action of Coffea canephora against dental biofilm. This coffee species caused bacterial lysis and consequent release of calcium into the medium. Furthermore, the advantage of coffee as an antibacterial beverage is that it is consumed in a concentrated form (6–10%) as opposed to various medicinal infusions that have shown such effect in vitro and are usually consumed at 1–2%. Therefore, a light roasted C. canephora aqueous extract can be considered as a potential anticariogenic substance.
This Letter presents a study of the local density of states (LDOS) in photonic quasicrystals. We show that the LDOS of a Penrose-type quasicrystal exhibits small additional band gaps. Among the band ...gaps, some exhibit a behavior similar to that typical of photonic crystals, while others do not. The development of certain band gaps requires large-size quasicrystals. It is explained by the long-range interactions involved in their formation. Moreover, the frequencies where the band gaps occur are not necessarily explained using single scattering and should therefore involve multiple scattering.
Two-dimensional aperiodic tilings are collections of polygons, devoid of any translational symmetries, capable of covering a plane without gaps and overlaps. Although aperiodic, these structures can ...exhibit order and symmetry in an extended sense. In this paper, we study the radiation properties of planar antenna arrays based on certain categories of two-dimensional aperiodic tilings that illustrate diverse aspects of aperiodic order. Background material on aperiodic tilings and their known electromagnetic properties is reviewed. Results are illustrated to highlight the effects of aperiodic order in the antenna array radiation properties. Potential applications are also envisaged
The advent of ultra-low noise microwave amplifiers revolutionized several research fields demanding quantum-limited technologies. Exploiting a theoretical bimodal description of a linear ...phase-preserving amplifier, in this contribution we analyze some of the intrinsic properties of a model architecture (i.e., an rf-SQUID based Josephson Traveling Wave Parametric Amplifier) in terms of amplification and noise generation for key case study input states (Fock and coherent). Furthermore, we present an analysis of the output signals generated by the parametric amplification mechanism when thermal noise fluctuations feed the device.
Abstract Objectives The antibacterial activity of Coffea canephora extract was evaluated in vitro against Streptococcus mutans and Streptococcus sobrinus . The viability of planktonic cells was ...analysed by susceptibility tests (MIC and MBC) and time-kill assays. The effect of the extract on dental demineralisation was also investigated. Methods Primary 1st molar fragments ( n = 24) were inoculated with a saliva pool and sustained in a multiple plaque growth system for 10 days to form biofilm. The biofilm was treated with light roasted C. canephora extract at 20%, Milli-Q water (negative control) and chlorhexidine (positive control) once a day, during a week. Blank controls comprised fragments without treatment. Biofilm pH was monitored in the last day of treatment. Changes in tooth mineralisation were assessed by cross-sectional microhardness (CSMH) test. Results MIC and MBC for S. mutans were 7 ± 2 mg/mL and 160 ± 0 mg/mL, respectively, showing no activity for S. sobrinus . The extract produced a 4-log reduction in the number of colonies of S. mutans after 3-h treatment ( p < 0.05) with undiluted extract (20%) and MBC concentration (16%). There was no difference among negative/blank controls and coffee plaque pH. Differences between CSMH values of dental fragments subjected to the coffee extract and to chlorhexidine were not significant. At depths up to 30 μm from the enamel surface, coffee extract and chlorhexidine promoted higher CSMH values when compared to blank/negative controls ( p < 0.05). Conclusion Our data suggest that light roasted C. canephora extract is beneficial as an anticariogenic substance.
Ultralow-noise microwave amplification and detection play a central role in different applications, going from fundamental physics experiments to the deployment of quantum technologies. In many ...applications the necessity of reading multiple detectors, or cavities or qubits, calls for large bandwidth amplifiers with the lowest possible noise. Current technologies are based on High Electron Mobility Transistors and Josephson Parametric Amplifiers. Both have limitations, the former in terms of the minimum noise, the latter in terms of bandwidth. Superconducting Traveling Wave Parametric Amplifiers (TWPAs) have the potential of offering quantum limited noise and large bandwidth. These amplifiers are based on the parametric amplification of microwaves traveling along a transmission line with embedded nonlinear elements. We are developing superconducting TWPAs based both on Josephson junction arrays (Traveling Wave Josephson Parametric Amplifiers) and on nonlinear kinetic inductance (Dispersion Engineered Traveling Wave Kinetic Inductance Amplifiers). Our goal is to achieve large bandwidth (in the 5 to 10 GHz range), large gain (more than 20 dB), large saturation power (more than −50 dBm), and near quantum limited noise (noise temperature less than 600 mK). Current achievements in the design and development of the high performance TWPAs are here reported and discussed, together with current limitations and possible future developments.
Reducing noise to the quantum limit over a large bandwidth is a fundamental requirement for future applications operating at millikelvin temperatures, such as the neutrino mass measurement, the ...next-generation X-ray observatory, the CMB measurement, the dark matter and axion detection, and the rapid high-fidelity readout of superconducting qubits. The read out sensitivity of arrays of microcalorimeter detectors, resonant axion-detectors, and qubits, is currently limited by the noise temperature and bandwidth of the cryogenic amplifiers. The Detector Array Readout with Traveling Wave Amplifiers project has the goal of developing high-performing innovative traveling wave parametric amplifiers with a high gain, a high saturation power, and a quantum-limited or nearly quantum-limited noise. The practical development follows two different promising approaches, one based on the Josephson junctions and the other one based on the kinetic inductance of a high-resistivity superconductor. In this contribution, we present the aims of the project, the adopted design solutions and preliminary results from simulations and measurements.
Multimaterial optical coatings are a promising viable option to meet the challenging requirements (in terms of transmittance, absorbance, and thermal noise) of next-generation gravitational wave ...detector mirrors. In this paper we focus on ternary coatings consisting of quarter-wavelength-thick layers, where a third material (H^{′}) is added to the two presently in use, namely, silica (L) and titania-doped tantala (H), featuring higher dielectric contrast (against silica) and lower thermal noise (compared with titania-doped tantala), but higher optical losses. We seek the optimal material sequences, featuring minimal thermal (Brownian) noise under prescribed transmittance and absorbance constraints, by exhaustive simulation over all possible configurations, for different values of the optical density and extinction coefficient of the third material, including the case of amorphous silicon and silicon nitride operating at ambient and cryogenic temperatures. In all cases studied, the optimal designs consist of a stack of (H^{′}|L) doublets topped by a stack of (H|L) doublets, confirming previous heuristic assumptions, and the achievable coating noise power spectral density reduction factor ranges from ∼0.5 at 290 K down to ∼0.1 at 20 K. The robustness of the found optimal designs against layer thickness deposition errors and uncertainties and/or fluctuations in the optical losses of the third material is also investigated. Possible margins for further thermal noise reduction by layer thickness optimization, and strategies to implement it, are discussed.
AIM
: This study aimed to investigate the in vitro effects of three paediatric liquid oral medicines on bovine dental enamel subsurfaces under pH cycling conditions.
METHODS
: Bovine enamel blocks ...were evaluated for surface hardness at baseline for sample selection. 52 intact bovine enamel blocks (16mm
2
) were randomly divided into four groups (n=13) according to the immersion treatments: G1: antibiotic (Klaricid®), G2: antihistamine (Claritin®), G3: antihistamine (Dimetapp®) and G4: control (de-ionised water). The blocks were submitted to pH cycling treatments twice a day for 12 days. The medicines were evaluated for pH, viscosity, and concentration of calcium, phosphate and fluoride. After the treatment period, cross-sectional microhardness (CSMH) measurements of the enamel blocks were taken and the data, expressed in Knoop hardness number (kg/mm
2
) was used to calculate the ΔS.
STATISTICS
: ANOVA followed by the Tukey test were used for statistical analyses (p<0.05).
RESULTS
: The antibiotic Klaricid® showed the highest concentration of fluoride, calcium and phosphate. Considering pH and viscosity, the following pattern was observed according to the treatment group: G4>G1>G2>G3 and G1>G2>G3>G4 respectively. Regarding the demineralisation pattern, the following results were observed: G4>G3>G2>G1. Compared to the control, the antibiotic and both the anti-histamines provoked less demineralisation of the enamel blocks (p<0.05).
CONCLUSIONS
: Antibiotic G1 (Klaricid ®sented an in vitro protective effect against acid attacks probably due to its mineral content and viscosity.
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