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Treatment of edentulous maxillary anterior region with horizontal ridge atrophy presents a clinical situation in which the placement of endosseous implants might be complex or sometimes impossible without a ridge augmentation procedure. This case report presents management of horizontally deficient maxillary anterior ridge with ridge split procedure using piezotome and simultaneous implant placement. In contrast to other ridge augmentation techniques, ridge splitting allows for immediate implant placement following surgery reducing the overall treatment time and eradicates the possible morbidity from a second surgical site. [ABSTRACT FROM AUTHOR]

The response of the electronic properties of the HfN2 monolayer to external perturbation, such as strain and electric fields, has been extensively investigated using density functional theory calculations for its device-based applications and photocatalysis. The HfN2 monolayer is found to be a semiconductor showing a direct band gap of 1.44 eV, which is widely tunable by 0.9 eV via application of biaxial strain. Furthermore, the tunability in the band edges of the HfN2 monolayer straddling the water redox potential under a biaxial strain of ±10% makes it suitable for solar energy harvesting via photocatalytic applications over a wide range (0–7) of pH. The band gap can be decreased by 29.8% under a biaxial tensile strain of 10%. Upon incorporation of spin orbit coupling (SOC) a large spin splitting at the conduction band (Δc ∼ 314 meV) and a small splitting at the valence band (Δv ∼ 32 meV) are noted, which is attributable to the orbital composition of the band edges. The spin splitting in the band edges is found to be adjustable via biaxial compressive strain. The strain dependent mechanical properties and stability reveal the ability of the HfN2 monolayer to withstand a large magnitude of strain of up to ±10%, thereby bringing about a giant tunability in its Young modulus (Y) from 66 N m−1 to 283 N m−1, which is gainfully exploitable in flexible electronics. The tunability in Y over such a wide range has not been observed in other 2D materials. Moreover, the HfN2 monolayer undergoes a transition from a semiconducting to a metallic state under the application of a normal electric field or gate voltage of 0.48 V Å−1, which may potentially serve as the OFF (semiconducting) and ON (metallic) state in devices. Interestingly, an electric field of such intensity has been realized experimentally using pulsed ac field technology. Such a small gate voltage will greatly lower its power consumption. The electronic origin of this transition from the OFF to the ON state is found to arise from unoccupied NFEG (Nearly Free Electron Gas) states. A HfN2 monolayer based tunnel field effect transistor (t-FET) is proposed herewith as a model device for low-power digital data storage, thereby paving new avenues in flexible electronics and memory devices. [ABSTRACT FROM AUTHOR]

Organic quinones conjugated with a conductive support like graphene via a covalent and/or non-covalent approach are emerging as low-cost and sustainable alternatives to conventional pseudocapacitive materials because of their fast and reversible redox kinetics. Herein, for the first time, reduced graphene oxide (rGO) networks functionalized with the eco-friendly dopamine (DA) moiety in a combined covalent and non-covalent manner have been explored by a facile hydrothermal synthesis method as high-performance pseudocapacitive materials. Further, a unique in situ electrochemical polymerization approach has been undertaken in an attempt to boost the overall storage capacity as well as cycling stability. Electrochemical tuning of the active material can result in an enhancement in the specific capacitance via dual improvement in faradaic and capacitive current as compared to the initial xerogel material, highlighting the significance of the in situ process. The electrode material shows a highest specific capacitance (CSP) of 348 F g−1 at a current density of 0.5 A g−1 in 1 M H2SO4 while retaining 60% of its initial capacitance even at a very high current density of 200 A g−1. A metal-free all-solid-state symmetric supercapacitor was developed with the in situ electropolymerized active material and the as-fabricated device exhibits an excellent CSP of 218 F g−1 at 0.325 A g−1 in 1 M PVA/H2SO4 gel electrolyte with a maximum energy density of 30.3 W h kg−1 and power density up to 13 kW kg−1. Most importantly, the material exhibited an extraordinary stability of 53 000 charge–discharge cycles while retaining 94% of its initial capacitance, while the device also shows an excellent capacitance retention of 92% even after 10 000 continuous cycles. Simultaneously, the DFT study was amended to understand the covalent and non-covalent interaction of the redox species, its charge storage mechanism and charge density distribution as well as to calculate the density of states. [ABSTRACT FROM AUTHOR]

The facile synthesis of a highly durable, low-cost and robust electrocatalyst for hydrogen generation from water is vital to address the existing environmental issues, as well as to provide an environmentally-friendly clean and green energy supply. Electrochemical deposition of single-phase nickel phosphide on galvanostatically deposited copper foam (Cuf@Ni5P4) core–shell nanostructure offers an innovation in the structural design of a new platform for novel electrocatalysts. The Cuf@Ni5P4 provides a superior three-dimensional conductive channel for ion transport during the catalytic process. The catalyst exhibits an excellent electrocatalytic activity towards the hydrogen evolution reaction (HER) in acidic media. The superhydrophilic and aerophobic properties of the porous electrode help the H2 gas bubbles to quickly leave the surface. Interestingly, it requires a very low overpotential of 90 mV for HER at a current density of 10 mA cm−2. The very small Tafel slope of 49 mV dec−1 and the very high exchange current density (∼0.76 mA cm−2) originate from the large electrochemically active surface area and the fast mass and electron transfer efficiency of the Cuf@Ni5P4 catalyst. A theoretical study was performed to investigate the mechanism underlying the HER activity in Cu-supported Ni5P4 at an atomic scale. Density functional theory (DFT) calculations suggest a very high negative Gibbs free energy change (ΔGH*) in Ni5P4 (0001)/Cu (111) upon hydrogen adsorption, which is actually responsible for the excellent HER activity of the catalyst. Furthermore, it shows remarkable durability for hydrogen generation under low (10 mA cm−2) and high current densities (160 mA cm−2) for >84 h with ∼96% retention of the overpotential, establishing a low-cost and efficient catalyst for sustainable, future energy generation strategies. [ABSTRACT FROM AUTHOR]

Photoconversion of carbon dioxide with water into renewable solar fuels using a single integrated system is the primary goal of artificial photosynthesis. The ease of applying mechanical strain reversibly in low dimensional materials can be exploited in optimizing their artificial photosynthetic or photocatalytic properties. In this work, strain effects on the concerted interplay of all the factors controlling the photocatalytic ability, such as suitable band edges straddling the redox potentials for CO2 reduction with the water and oxygen evolution reactions, optical absorbance and conductivity, carrier mobilities, carrier mobility ratios (i.e. hole/electron or electron/hole mobility ratio) and exciton binding energies, have been comprehensively studied on monolayer MoS2 nanosheets and calibrated, using density functional theory, to ascertain the type and magnitude of strain under which the optical absorbance and conductivity, carrier mobilities and the carrier mobility ratio are simultaneously and optimally enhanced, while the requisite redox reactivity and small exciton binding energies are retained. Additionally, the role of pH has been carefully addressed. Optical conductivity in pristine ML-MoS2 calculated in this work agrees with the experimental ones. Of all strain types studied, shear strain is found to be most effective in driving the kinetics of the light-driven reduction of CO2 with water, water reduction in the absence of CO2 [i.e. the H2 evolution reaction (HER)] and oxidation of water [i.e., the O2 evolution reaction (OER)] with nearly the same efficiency. The optical absorbance and conductivity are found to reach their maximum magnitude at 3% shear strain along the direction of lattice dilation. 0.5–3.5 and 0.5–6.5 ranges in pH are found to be favorable for the photo-catalytic HER and CO2 reduction with water respectively. Carrier mobility has been calculated using a more reliable and robust formulation where the carrier mobility depends not only on the carrier effective mass, deformation potential and elastic modulus along the longitudinal charge transport direction but also on these parameters along the transverse direction. Shear strain induces the maximum enhancement in carrier mobilities and the carrier mobility ratio, which facilitates the separation and migration of e−–h+ pairs along opposite or transverse directions and thereby in prolonging the carrier lifetimes, i.e., lowering their recombination rates. [ABSTRACT FROM AUTHOR]

MoS2 nanostructures, i.e., nanoribbons, nano-mesh, etc., may open different prospect of applications in nano-electronic and opto-electronic devices and sensors. However, the fabrication of these complicated nanostructures can be executed by using standard nano-patterning techniques such as lithography, printing, etc. Nevertheless, these standard techniques involve affluent multistep processes to optimize scalability, form factors and accuracy in the feature size. Herein, we demonstrate the fabrication of unique nano-structures on MoS2, such as nano-ribbons and nano-mesh, by a simple one-step process of direct laser writing using 532 nm low power focused laser. The minimum power required to etch a MoS2 layer for a 532nm laser is found to be ~6.95 mW and the minimum void size observed is ~300 nm, which is very close to the diffraction limit of the laser used. Both the experimental and computational results have shown that the voids induced by laser etching always take a hexagonal or triangular shape, which can be used to define crystal orientation of the MoS2 flake. Investigation shows that the periphery of hexagonal voids lies on S atoms, whereas for triangular voids, it lies on Mo atoms of the MoS2 crystal. In-depth AFM and Raman analysis show that the etching rate is tunable by controlling the laser power and the exposure time. [ABSTRACT FROM AUTHOR]