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Journal of Oral Biology and... 2024The permanence of deep subgingival restorations are questionable both functionally and biologically. Crown lengthening is one of the traditionally performing procedures... (Review)
Review
The permanence of deep subgingival restorations are questionable both functionally and biologically. Crown lengthening is one of the traditionally performing procedures to visualize and relocate the deep margins, but the limitations of the invasive surgical procedure are anatomical complications like exposure of root concavities or furcation, violation of biological width, post operative discomfort because of sutures or periodontal packs; and less patient compliance. Other than crown lengthening, researchers tried some other techniques like modified matrix adaptation technique, using retraction cord, making holes in matrix band and flowing resin modified glass ionomer cement (RMGIC) to the root or cervical caries, orthodontic extrusion. But most of these procedures are failed to give adequate clinical success. Deep margin elevation (DME) is one of the minimally invasive and successful procedure performing in deep subgingival caries. But the evidences and knowledge in this technique is limited among practitioners. This review is to evaluate the applicability of DME, the current clinical concepts, techniques and materials for DME; and a comparison with traditionally used various techniques for cervical margin relocation also concluding that currently available various clinical parameters with this technique.
PubMed: 38481655
DOI: 10.1016/j.jobcr.2023.12.002 -
The Journal of Physical Chemistry. C,... Mar 2024We present a theoretical model to compute the efficiency of the generation of two or more electron-hole pairs in a semiconductor by the absorption of one photon via the...
We present a theoretical model to compute the efficiency of the generation of two or more electron-hole pairs in a semiconductor by the absorption of one photon via the process of carrier multiplication (CM). The photogeneration quantum yield of electron-hole pairs is calculated from the number of possible CM decay pathways of the electron and the hole. We apply our model to investigate the underlying cause of the high efficiency of CM in bulk 2H-MoTe, as compared to bulk PbS and PbSe. Electronic band structures were calculated with density functional theory, from which the number of possible CM decay pathways was calculated for all initial electron and hole states that can be produced at a given photon energy. The variation of the number of CM pathways with photon energy reflects the dependence of experimental CM quantum yields on the photon energy and material composition. We quantitatively reproduce experimental CM quantum yields for MoTe, PbS, and PbSe from the calculated number of CM pathways and one adjustable fit parameter. This parameter is related to the ratio of Coulomb coupling matrix elements and the cooling rate of the electrons and holes. Large variations of this fit parameter result in small changes in the modeled quantum yield for MoTe, which confirms that its high CM efficiency can be mainly attributed to its extraordinary large number of CM pathways. The methodology of this work can be applied to analyze or predict the CM efficiency of other materials.
PubMed: 38476826
DOI: 10.1021/acs.jpcc.4c00383 -
Polymers Mar 2024The application of absorbing materials for electromagnetic shielding is becoming extensive, and the use of absorbents is one of the most important points of preparing...
The application of absorbing materials for electromagnetic shielding is becoming extensive, and the use of absorbents is one of the most important points of preparing absorbing foam materials. In this work, epoxy resin was used as the matrix and carbonyl iron powder (CIP) was used as the absorbent, and the structural absorbing foam materials were prepared by the ball mill dispersion method. Scanning electron microscopy showed that the CIP was evenly dispersed in the resin matrix. The foam structures formed at pre-polymerization times of 10 min, 30 min and 50 min were analyzed, and it was found that the cell diameter decreased from 0.47 mm to 0.31 mm with the increase in the pre-polymerization time. The reflectivity of the frontal and reverse sides of the foam gradually tends to be unified at frequencies of 2-18 GHz. When the CIP content increased from 30 wt% to 70 wt%, the cell diameter increased from 0.32 mm to 0.4 mm, and the uniformity of CIP distribution deteriorated. However, with the increase in the CIP content, the absorption properties of the composite materials were enhanced, and the absorption frequency band broadened. When the CIP content reached 70 wt%, the compression strength and modulus of the foam increased to 1.32 MPa and 139.0 MPa, respectively, indicating a strong ability to resist deformation.
PubMed: 38475381
DOI: 10.3390/polym16050698 -
RSC Advances Feb 2024High-purity reduced graphene oxide (RGO or rGO) with appreciable conductivity is a desired conductive filler for lightweight polymer composites used in coatings,...
Scalable synthesis of high-quality, reduced graphene oxide with a large C/O ratio and its dispersion in a chemically modified polyimide matrix for electromagnetic interference shielding applications.
High-purity reduced graphene oxide (RGO or rGO) with appreciable conductivity is a desired conductive filler for lightweight polymer composites used in coatings, electronics, catalysts, electromagnetic interference (EMI) shielding, and energy storage devices. However, the intrinsic conductivity and the uniform dispersion of RGO in relatively polar matrices are challenging, leading to poor overall conductivity and performance of the composite material. The reported study improved the RGO intrinsic conductivity by increasing its C/O ratio while also simultaneously enhancing its compatibility with the polyimide (PI) matrix through ester linkages for better dispersion. A two-step reduction method drastically increased the number of structural defects and carbon content in the resulting RGO, corresponding to a maximum / and C/O of 1.54 and ∼87, respectively. Moreover, the 2D nanosheets with limited hydroxyl (-OH) groups effectively interacted with anhydride-terminated polyamic acid (AT-PAA) through chemical linkages to make high-performance RGO/PI nanocomposites. Consequently, the polymer matrix composites possessed the highest direct current conductivity of 15.27 ± 0.61 S cm for 20 wt% of the prepared RGO. Additionally, the composite material was highly stiff (3.945 GPa) yet flexible (easily bent through 180°), lightweight (∼0.34 g cm), and capable of forming thin films (162 ± 15 μm). Unlike most polymer matrix composites, it showcased one of its class's highest thermal stabilities (a weight loss of only 5% at 638 °C). Ultimately, the composite performed as an effective electromagnetic interference (EMI) shielding material in the X-Band (8 to 12 GHz), demonstrating outstanding shielding effectiveness (SE), shielding effectiveness per unit thickness (SE), specific shielding effectiveness (SSE), and absolute shielding effectiveness (SSE) of 46 dB, 2778 dB cm, 138 dB cm g, and 8358 dB cm g, respectively. As a consequence of this research, the high-purity RGO and its high-performance PI matrix nanocomposites are anticipated to find practical applications in conductive coatings and flexible substrates demanding high-temperature stability.
PubMed: 38440276
DOI: 10.1039/d4ra00329b -
Frontiers in Plant Science 2024Secondary salinization is a crucial constraint on agricultural progress in arid regions. The specific mulching irrigation technique not only exacerbates secondary...
Secondary salinization is a crucial constraint on agricultural progress in arid regions. The specific mulching irrigation technique not only exacerbates secondary salinization but also complicates field-scale soil salinity monitoring. UAV hyperspectral remote sensing offers a monitoring method that is high-precision, high-efficiency, and short-cycle. In this study, UAV hyperspectral images were used to derive one-dimensional, textural, and three-dimensional feature variables using Competitive adaptive reweighted sampling (CARS), Gray-Level Co-occurrence Matrix (GLCM), Boruta Feature Selection (Boruta), and Brightness-Color-Index (BCI) with Fractional-order differentiation (FOD) processing. Additionally, three modeling strategies were developed (Strategy 1 involves constructing the model solely with the 20 single-band variable inputs screened by the CARS algorithm. In Strategy 2, 25 texture features augment Strategy 1, resulting in 45 feature variables for model construction. Strategy 3, building upon Strategy 2, incorporates six triple-band indices, totaling 51 variables used in the model's construction) and integrated with the Seagull Optimization Algorithm for Random Forest (SOA-RF) models to predict soil electrical conductivity (EC) and delineate spatial distribution. The results demonstrated that fractional order differentiation highlights spectral features in noisy spectra, and different orders of differentiation reveal different hidden information. The correlation between soil EC and spectra varies with the order. 1.9th order differentiation is proved to be the best order for constructing one-dimensional indices; although the addition of texture features slightly improves the accuracy of the model, the integration of the three-waveband indices significantly improves the accuracy of the estimation, with an R of 0.9476. In contrast to the conventional RF model, the SOA-RF algorithm optimizes its parameters thereby significantly improving the accuracy and model stability. The optimal soil salinity prediction model proposed in this study can accurately, non-invasively and rapidly identify excessive salt accumulation in drip irrigation under membrane. It is of great significance to improve the growing conditions of cotton, increase the cotton yield, and promote the sustainable development of Xinjiang's agricultural economy, and also provides a reference for the prevention and control of regional soil salinization.
PubMed: 38439983
DOI: 10.3389/fpls.2024.1358965 -
Strip loaded waveguide amplifiers based on erbium-doped nanocomposites with 17 dB internal net gain.Optics Express Feb 2024We propose a strip loaded amplifier employing SU-8 as the loaded waveguide and nanoparticles (NPs)-polymethyl methacrylate (PMMA) as the cladding layer. By leveraging...
We propose a strip loaded amplifier employing SU-8 as the loaded waveguide and nanoparticles (NPs)-polymethyl methacrylate (PMMA) as the cladding layer. By leveraging the undoped SU-8 loaded waveguide, the polymer waveguide amplifier accomplished remarkably low transmission losses, reaching as low as 1.8 dB/cm at 1530 nm. We prepared NPs-PMMA nanocomposite by utilizing NaLuYF: Er, Yb @NaLuF core-shell nanoparticles, which exhibited a significantly enhanced lifetime of 6.15 ms. An internal net gain of up to 17.7 dB was achieved on a strip loaded waveguide with a length as short as 0.5 cm when the on-chip pump power was 77 mW. Signal enhancement (SE) was measured at different wavelengths, revealing that the strip loaded waveguide exhibited broadband SE ranging from 1510 nm to 1570 nm, covering the C-band. To the best of our knowledge, this work has achieved the highest gain results reported thus far on a polymer matrix and provides an efficient method for optical amplification in passive devices on silicon and SiN platforms, leveraging the ease of integration of polymer materials with diverse photonic platforms.
PubMed: 38439462
DOI: 10.1364/OE.514318 -
Optics Express Feb 2024Single-frequency fiber lasers at S-, C-, and L-bands play a crucial role in various applications such as optical network expansion, high-precision metrology, coherent...
Single-frequency fiber lasers at S-, C-, and L-bands play a crucial role in various applications such as optical network expansion, high-precision metrology, coherent lidar, and atomic physics. However, compared to the C-band, the S- and L-bands have wavelength deviations and suffer from excited-state absorption, which limits the output performance. To address this issue, a strategy called ion hybridization has been proposed to increase the differences in site locations of rare earth (RE) ions in the laser matrix, thereby achieving a broader gain bandwidth. This strategy has been applied to an Er/Yb co-doped modified phosphate fiber (EYMPF), resulting in gain coefficients per unit length greater than 2 dB/cm at S-, C-, and L-bands. To demonstrate its capabilities, several centimeter-long EYMPFs have been used to generate single-frequency laser outputs at S-, C- and L-bands with kHz-linewidths, high signal-to-noise ratios (>70 dB), and low relative intensity noise (<-130 dB/Hz) in a compact short linear-cavity configuration.
PubMed: 38439233
DOI: 10.1364/OE.511524 -
JPMA. the Journal of the Pakistan... Feb 2024To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system. (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To evaluate composite class II restoration proximal contacts and contours by comparing saddlecontoured metal matrix and pre-contoured self-adhesive matrix system.
METHODS
The randomised controlled trial (NCT05414656) was conducted at the Department of Operative Dentistry, School of Dentistry, Shaheed Zulfiqar Ali Bhutto Medical University, Pakistan Institute of Medical Sciences, Islamabad, Pakistan, from May to October 2022, and comprised of patients having supra-gingival class II cavities. They were randomised into class II restoration with saddle-contoured matrix band group A, and restoration with pre-contoured self-adhesive matrix group B. The tightness of proximal contacts was evaluated using the Fédération Dentaire Internationale criteria and the quality of proximal contours was assessed using clinical and radiographic examination. Data was analysed using SPSS 16.
RESULTS
Of the 60 subjects, 42(70%) were females and 18(30%) were males. The overall mean age was 38.03±15.33 years. There were 30(50%) subjects in each of the 2 groups. The highest restoration was needed in the upper premolar 20(33.3%). The tightness of proximal contact was not significantly different between the groups (p=0.94). Clinical examination for production of good contours was higher in group A compared to group B, but the difference was not significant (p>0.05).
CONCLUSIONS
There was no significant difference between saddle-contoured metal matrix and pre-contoured selfadhesive matrix for composite class II restoration proximal contacts and contours.
CLINICAL TRIAL LINK
https://clinicaltrials.gov RCT (NCT05414656).
Topics: Male; Female; Humans; Young Adult; Adult; Middle Aged; Composite Resins; Resin Cements; Matrix Bands; Research Design; Bicuspid; Dental Restoration, Permanent
PubMed: 38419215
DOI: 10.47391/JPMA.8627 -
ACS Omega Feb 2024Assemblies of photochromic molecules feature exciton states, which govern photochemical and photophysical processes in multichromophoric systems. Understanding the...
Visible Light Induced Exciton Dynamics and -to- Isomerization in Azobenzene Aggregates: Insights from Surface Hopping/Semiempirical Configuration Interaction Molecular Dynamics Simulations.
Assemblies of photochromic molecules feature exciton states, which govern photochemical and photophysical processes in multichromophoric systems. Understanding the photoinduced dynamics of the assemblies requires nonadiabatic treatment involving multiple exciton states and numerous nuclear degrees of freedom, thus posing a challenge for simulations. In this work, we address this challenge for aggregates of azobenzene, a prototypical molecular switch, performing on-the-fly surface hopping calculations combined with semiempirical configuration interaction electronic structure and augmented with transition density matrix analysis to characterize exciton evolution. Specifically, we consider excitation of azobenzene tetramers in the nπ* absorption band located in the visible (blue) part of the electromagnetic spectrum, thus extending our recent work on dynamics after ππ* excitation corresponding to the ultraviolet region [Titov, , , 13678-13688]. We find that the nπ* excitons, which are initially strongly localized by ground-state conformational disorder, undergo further (very strong) localization during short-time photodynamics. This excited-state localization process is extremely ultrafast, occurring within the first 10 fs of photodynamics. We observe virtually no exciton transfer of the localized excitons in the nπ* manifold. However, the transfer may occur via secondary pathways involving ππ* states or the ground state. Moreover, we find that the nπ* quantum yields of the -to- isomerization are reduced in the aggregated state.
PubMed: 38405525
DOI: 10.1021/acsomega.3c09900