Bionic effects of nano hydroxyapatite dentifrice on demineralised surface of enamel post orthodontic debonding: in-vivo split mouth study

Background Orthodontic debonding procedure produces inevitable enamel surface alterations, sequelae to which are enamel demineralization, sensitivity and retention of pigments. Several agents have been employed to counterbalance the same. The purpose of this study was (1) To evaluate the hypothesis that no significant difference exists in the remineralising potential of nano hydroxyapatite (NanoHAP) dentifrice and fluoridated dentifrice after orthodontic debonding, (2) To estimate the enamel topographic parameters following use of nano HAP dentifrice, post orthodontic debonding. Methods Sixty upper first bi-cuspids (30 subjects) planned for therapeutic extraction for the orthodontic treatment were bonded with a light cured adhesive. Envelope method of randomisation was followed in this prospective in-vivo study. In each subject, one of the first premolar brackets was debonded using a debonding plier and polished following standard protocols. Envelope method of randomisation was used to determine the side of the premolar to be debonded first. Patient was advised to use fluoridated (Group I) dentifrice for the first 15 days, then the first premolar was covered with a heavy-bodied putty cap, extracted and subjected to atomic force microscopy (AFM). Contralateral first premolar was then debonded and polished using similar protocol, and patient was advised to use nano hydroxyapatite dentifrice (Group II) for next 15 days. The premolar was then extracted and analyzed for surface roughness using AFM. The remineralizing potential of dentifrices was assessed by evaluating surface roughness parameters of the two groups and were compared using a two-sample t test. Results A significant difference was found amongst Group I (Fluoridated dentifrice) and Group II (NanoHAP dentifrice) (p > 0.001***) for enamel surface roughness variables which reflect remineralising potential of dentifrices. Group II showed significantly lesser value of surface roughness characteristics. Conclusions NanoHAP dentifrice was shown, after 15 days, to be superior to fluoridated dentifrice in remineralising enamel post orthodontic debonding.

Retrieval of Optical Constants of Undoped Flash-Evaporated Lead Iodide Films from an Analysis of Their Normal Incidence Transmission Spectra Using Swanepoel’s Transmission Envelope Theory of Non-Uniform Films

Normal-incidence transmission-wavelength (T_exp (λ)-λ) spectra of 1 and 1.2 m thick flash-evaporated lead iodide (PbI2) films on 1.1 mm thick glass slides held at 200 ℃ display well-spaced several interference-fringe maxima and minima in the λ-range 520-900 nm, without exhibiting a transparent region and with the maxima lying well below the substrate transmission. Below 520 nm, these T_exp (λ)-λ curves drop steeply to zero (at λ ≼ 505 nm), signifying crystalline-like PbI2 film absorption. As corrections of measured (PbI2 film/substrate) transmittance data for substrate absorption and spectrometer slit-width effect were marginal over the studied λ-range, the observed low transmittance of (PbI2 film/substrate) system was related to PbI2 film thickness non-uniformity (∆d), which causes shrinkage of both maxima and minima and leads to significant film optical absorption that reduces both maxima and minima. The McClain ENVELOPE algorithm was utilized, with a minor modification, to construct maxima T_M (λ_max/λ_min) and minima T_m (λ_min/λ_max) envelope curves, which were analyzed by Swanepoel’s envelope method of non-uniform films using an approach that takes account of dispersive substrate refractive index n_s (λ) and circumvents the non-availability of a high-λ transparency region. In such analytical approach, ∆d was varied till a re-generated T_gen (λ)-λ curve matches the T_exp (λ)-λ curve. An average thickness d ̅ of the film, besides its refractive index n(λ) and absorption coefficient α(λ) in the weak, medium and strong absorption regions, were then obtained. The energy-dependence of α(λ) is discussed in view of interband electronic transition models. The obtained results are consistent with other literature studies on similar flash-evaporated PbI2 films. Keywords: PbI2, Optical constants and bandgap, Swanepoel's transmission envelope method, Non-uniform films.

Further Increasing the Accuracy of Characterization of a Thin Dielectric or Semiconductor Film on a Substrate from Its Interference Transmittance Spectrum

Three means are investigated for further increasing the accuracy of the characterization of a thin film on a substrate, from the transmittance spectrum T(λ) of the specimen, based on the envelope method. Firstly, it is demonstrated that the accuracy of characterization, of the average film thickness d¯ and the thickness non-uniformity ∆d over the illuminated area, increases, employing a simple dual transformation utilizing the product T(λ)xs(λ), where Tsm(λ) is the smoothed spectrum of T(λ) and xs(λ) is the substrate absorbance. Secondly, an approach is proposed for selecting an interval of wavelengths, so that using envelope points only from this interval provides the most accurate characterization of d¯ and ∆d, as this approach is applicable no matter whether the substrate is transparent or non-transparent. Thirdly, the refractive index n(λ) and the extinction coefficient k(λ) are computed, employing curve fitting by polynomials of the optimized degree of 1/λ, instead of by previously used either polynomial of the optimized degree of λ or a two-term exponential of λ. An algorithm is developed, applying these three means, and implemented, to characterize a-Si and As98Te2 thin films. Record high accuracy within 0.1% is achieved in the computation of d¯ and n(λ) of these films.

Determination of Optical Constants and Thickness of Nanostructured ZnO Film by Spin Coating Technique

In this report, we have investigated optical constants and thickness of nanostructured ZnO films grown on a glass substrate by sol-gel spin coating technique using zinc acetate as precursor. Optical constants such as complex refractive index ñ and dielectric constant ϵ determined from the transmittance spectrum in the ultraviolet, visible, near infrared (UV-VIS, NIR) region by envelope method. The value of refractive index decreases from 2.34 to 1.86 and extinction coefficient increases from 0.28 to 0.64 with increasing wavelength. The decreasing behavior of refractive index is attributed due to the increase in transmission and decrease in absorption coefficient with increasing wavelength. The film exhibits reasonably high transmittance (>80%) in the visible region. Absorbance coefficient α and film thickness (d) were calculated from the interference of fringes of transmittance spectrum. The band gap and thickness of the film were found 3.02 eV and 275nm, respectively. The thickness of the film measured by envelope method is validated with cross-section micrograph of SEM images which is about 285 nm. The real part of the dielectric function of nanostructured ZnO decreases with increasing wavelength where as the imaginary part of dielectric constant increases with increasing wavelength. The observed high value of refractive index n and real part of dielectric constant ϵ at lower wavelength is due to band edge absorption of carriers. The dispersion relation shows the increase of complex refractive index and dielectric constant at the high frequency regime is due to the discharging of defect levels using optical excitation of carriers in the visible region.

ANALYSIS OF DIMENSIONAL AND CALCULATIONS STRUCTURE DESIGNED BASED ON SNI 2847-2013

Floor slabs are structural components of a building that have certain dimensions to transmit dead and live loads on them to be distributed to their supports. Designing the floor slabs of a building, load data will be borne by the structure, so that the planned structure is able to bear the loads and forces that work. With careful planning, it is expected that the dimensions and reinforcement of the floor slabs are economical and safe which can avoid deflection and cracks. The building being reviewed is hospitals in Surabaya. This building consists of 9 floors with a height of up to 37 m. Planning dimensions and reinforcement in this hospital building includes two-way slabs with different size variations. The analysis was carried out using the 'envelope method' in accordance with SNI 2847: 2013 (Basics of Reinforced Concrete Planning). The results of the analysis of dimensions and reinforcement in this hospital building are: a) the dimensions / thickness of the plate on the roof plate is 125 mm, while b) the reinforcement used on this floor plate is Ø10-125 and the reinforcement for Ø10-200. Each moment analyzed is contained in the analysis results table and floor slab reinforcement drawings.

A Novel Maneuver-Based Driving Envelope Generation Approach for Driving Safety Assessment

It is of utmost importance for advanced driver assistance systems to evaluate the risk of the current situation and make continuous decisions about what kind of evasive maneuver can be initiated. The purpose of this paper is to establish efficient indicators to evaluate the risk of candidate driving maneuvers for a human-in-the-loop vehicle. A novel safe driving envelope generation method is proposed, which takes various constraints into consideration, including the human operation, vehicle motion limits, and collision avoidance with road boundary and obstacles. The efficiency of the proposed method is validated by simulation experiments and real vehicle tests. The results show that the feasibility of candidate driving maneuvers can be efficiently determined by computing the driving envelope, and the proposed driving envelope method can be easily implemented for real-time applications.

Theoretical study of optical properties of optical anti-reflection films

In this paper, the theoretical calculation of the characteristics of the optical film, including the basic theory of the film, the calculation of the characteristics of the single-layer film, and the calculation of the characteristics of the multilayer film, to achieve a certain degree of understanding of the characteristics of the optical film. And through the optical anti-reflection film The design principle, material selection, and process mastering have a deeper understanding of the anti-reflection film. The transmission spectrum is used to calculate the “envelope method” The refractive index, thickness, absorption coefficient, an extinction coefficient of the film to analyze the optical performance of the film.