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This work reviews fundamentals and the recent state-of-art achievements in the field of plasmonic biosensing based terahertz (THz) spectroscopy. Being nonpoisonous and nondestructive ...to the human tissues, THz signals offer promising, cost-effective, and real-time biodevices for practical pharmacological applications such as enzyme reaction analysis. Rapid developments in the field of THz plasmonics biosensors and immunosensors have brought many methodologies to employ the resonant subwavelength structures operating based on the fundamental physics of multipoles and asymmetric lineshape resonances. In the ongoing hunt for new and advanced THz plasmonic biosensors, the toroidal metasensors have emerged as excellent alternates and are introduced to be a very promising technology for THz immunosensing applications. Here, we provide examples of recently proposed THz plasmonic metasensors for the detection of thin films, chemical and biological substances. This review allows to compare the performance of various biosensing tools based on THz plasmonic approach and to understand the strategic role of toroidal metasensors in highly accurate and sensitive biosensors instrumentation. The possibility of using THz plasmonic biosensors based on toroidal technology in modern medical and clinical practices has been briefly discussed.
Hydrogen fuel produced from water splitting using solar energy and a catalyst is a clean and renewable future energy source. Great efforts in searching for photocatalysts that are highly efficient, ...inexpensive, and capable of harvesting sunlight have been made for the last decade, which, however, have not yet been achieved in a single material system so far. Here, we predict that MoS2/AlN(GaN) van der Waals (vdW) heterostructures are sufficiently efficient photocatalysts for water splitting under visible-light irradiation based on ab initio calculations. Contrary to other investigated photocatalysts, MoS2/AlN(GaN) vdW heterostructures can separately produce hydrogen and oxygen at the opposite surfaces, where the photoexcited electrons transfer from AlN(GaN) to MoS2 during the photocatalysis process. Meanwhile, these vdW heterostructures exhibit significantly improved photocatalytic properties under visible-light irradiation by the calculated optical absorption spectra. Our findings pave a new way to facilitate the design of photocatalysts for water splitting.
Phosphorene has attracted intense interest due to its unexpected high carrier mobility and distinguished anisotropic optoelectronic and electronic properties. In this work, we unraveled strain ...engineered phosphorene as a photocatalyst in the application of water splitting hydrogen production based on density functional theory calculations. Lattice dynamic calculations demonstrated the stability for such kind of artificial materials under different strains. The phosphorene lattice is unstable under compression strains and could be crashed, whereas phosphorene lattice shows very good stability under tensile strains. Further guarantee of the stability of phosphorene in liquid water is studied by ab initio molecular dynamics simulations. Tunable band gap from 1.54 eV at ambient condition to 1.82 eV under tensile strains for phosphorene is evaluated using parameter-free hybrid functional calculations. Appropriate band gaps and band edge alignments at certain pH demonstrate the potential application of phosphorene as a sufficiently efficient photocatalyst for visible light water splitting. We found that the strained phosphorene exhibits significantly improved photocatalytic properties under visible-light irradiation by calculating optical absorption spectra. Negative splitting energy of absorbed H2O indicates the water splitting on phosphorene is energy favorable both without and with strains.
Two-dimensional (2D) materials have shown extraordinary performances as photocatalysts compared to their bulk counterparts. Simulations have made a great contribution to the deep understanding and ...design of novel 2D photocatalysts.
Ab initio
simulations based on density functional theory (DFT) not only show efficiency and reliability in new structure searching, but also can provide a reliable, efficient, and economic way for screening the photocatalytic property space. In this review, we summarize the recent developments in the field of water splitting using 2D materials from a theoretical perspective. We address that DFT-based simulations can fast screen the potential spaces of photocatalytic properties with the accuracy comparable to experiments, by investigating the effects of various physical/chemical perturbations. This, at last, will lead to the enhanced photocatalytic activities of 2D materials, and promote the development of photocatalysis.
Two-dimensional (2D) materials have shown extraordinary performances as photocatalysts compared to their bulk counterparts.
Abstract There is not much level 1 evidence based literature to guide management of hypertrophic scars and keloids despite an array of therapeutic modalities at disposal. Intralesional (i/l) ...triamcinolone injections have remained a gold standard in non surgical management. Sporadic reports on use of i/l verapamil suggest its efficacy. Since verapamil has not found sufficient mention as an effective alternative modality, it was decided to undertake a randomized study which could also address some additional clinical parameters. A randomized, parallel group and observer blinded comparison with 40 patients (48 scars) was carried out to compare the effects of i/l triamcinolone (T) (22 scars) and verapamil injections (V) (26 scars). 1.5 ml was the maximum indicative volume decided in the study protocol for both the drugs (triamcinolone @40 mg/ml and verapamil @ 2.5 mg/ml). Patients included were aged between 15–60 years with scars ranging between 0.5–5 cm (but total area roughly <6 cm2 ), and scars under 2 years duration. Patients with keloidal diathesis were excluded. Injections were scheduled every three weeks until complete flattening of the scar or eight sessions, which ever came earlier. No concomitant therapies like massage, silicone gel or pressure garments were used. Scar evaluation at each stage was done by serial photographic records as well as by Vancouver Scar Scale (VSS). Comparative survival analysis between the two drugs was done using Kaplan Meier curves, and VSS scores were analyzed using Wilcoxon test and log rank test. Mean zero VSS scores were achieved with treatments in respect of scar height (T-12 weeks, V-21 weeks), vascularity (T-15 weeks, V-18 weeks) and pliability (T-15 weeks, V-21 weeks). The improvement in scar vascularity and pliability kept pace with decrease in scar height, in both the groups. There was not much difference in the rate of change of scar pigmentation with either drug but almost 60% patients in both the groups regained normal pigmentation. Our study adds to evidence of verapamil's capability in flattening the raised scars. With an extremely low cost and fewer adverse effects it deserves better positioning in the wide armamentarium against hypertrophic scars. It also offers several therapeutic possibilities to alternate with triamcinolone or be used simultaneously in larger (or multiple) scars.
To the league of rapidly expanding 2D materials, borophene is a recent addition. Herein, a combination of ab initio density functional theory (DFT) and nonequilibrium Green’s function (NEGF) based ...methods is used to estimate the prospects of this promising elemental 2D material for gas sensing applications. We note that the binding of target gas molecules such as CO, NO, NO2, NH3, and CO2 is quite strong on the borophene surface. Interestingly, our computed binding energies are far stronger than several other reported 2D materials like graphene, MoS2, and phosphorene. Further rationalization of stronger binding is made with the help of charge transfer analysis. The sensitivity of the borophene for these gases is also interpreted in terms of computing the vibrational spectra of the adsorbed gases on top of borophene, which show dramatic shift from their gas phase reference values. The metallic nature of borophene enables us to devise a setup considering the same substrate as electrodes. From the computation of the transmission function of system (gas + borophene), appreciable changes in the transmission functions are noted compared to pristine borophene surface. The measurements of current–voltage (I–V) characteristics unambiguously demonstrate the presence and absence of gas molecules (acting as ON and OFF states), strengthening the plausibility of a borophene based gas sensing device. As we extol the extraordinary sensitivity of borophene, we assert that this elemental 2D material is likely to attract subsequent interest.
Abstract
We studied the physical, electronic transport and optical properties of a unique pentagonal PdQ
2
(Q = S, Se) monolayers. The dynamic stability of 2Dwrinkle like-PdQ
2
is proven by positive ...phonon frequencies in the phonon dispersion curve. The optimized structural parameters of wrinkled pentagonal PdQ
2
are in good agreement with the available experimental results. The ultimate tensile strength (UTHS) was calculated and found that, penta-PdS
2
monolayer can withstand up to 16% (18%) strain along
x
(
y
) direction with 3.44 GPa (3.43 GPa). While, penta-PdSe
2
monolayer can withstand up to 17% (19%) strain along
x
(
y
) dirrection with 3.46 GPa (3.40 GPa). It is found that, the penta-PdQ
2
monolayers has the semiconducting behavior with indirect band gap of 0.94 and 1.26 eV for 2D-PdS
2
and 2D-PdSe
2
, respectively. More interestingly, at room temperacture, the hole mobilty (electron mobility) obtained for 2D-PdS
2
and PdSe
2
are 67.43 (258.06) cm
2
V
−1
s
−1
and 1518.81 (442.49) cm
2
V
−1
s
−1
, respectively. In addition, I-V characteristics of PdSe
2
monolayer show strong negative differential conductance (NDC) region near the 3.57 V. The Shockly-Queisser (SQ) effeciency prameters of PdQ
2
monolayers are also explored and the highest SQ efficeinciy obtained for PdS
2
is 33.93% at −5% strain and for PdSe
2
is 33.94% at −2% strain. The penta-PdQ
2
exhibits high optical absorption intensity in the UV region, up to 4.04 × 10
5
(for PdS
2
) and 5.28 × 10
5
(for PdSe
2
), which is suitable for applications in optoelectronic devices. Thus, the ultrathin PdQ
2
monolayers could be potential material for next-generation solar-cell applications and high performance nanodevices.
By performing density-functional calculations, we have investigated the electronic bandgap of single epitaxial and multiepitaxial graphene layers on SiC. The calculations show that a defect-free ...graphene layer above the carbon buffer layer is very flat and no bandgap is found in the Dirac bands. By introducing a finite density of Stone−Wales defects in the graphene layer(s), we find that a bandgap is opened and decreases as the thickness of graphene layers increases, in good agreement with experiments. The band splitting and the charge distribution vary greatly with the number of graphene layers. The bandgap opening is due to the symmetry breaking within the single graphene layer. The narrowing of the bandgap in multiple graphene layers is induced by interlayer interaction.
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