Double Band Research Articles

Engineering Relaxation-Paths of C-Exciton for Constructing Band Nesting Bypass in WS2 Monolayer.

Transition-metal dichalcogenides exhibit strong photon absorption characteristics in the band nesting region (denoted as C-exciton) due to intrinsic van Hove singularities despite being atomically thin. However, because of unique parallel band structure and ineluctably unfavorable recombination process, only a small fraction of the hot carriers from C-excitons are converted into optically active band-edge excitons via inherent relaxation-paths. The resultant photoluminescence quantum yield (PLQY) is severely suppressed for the resonant excitation of C-exciton. To overcome this limitation, we have designed double type-I band alignments to construct a band nesting bypass in a monolayer WS2/CdS quantum dot heterostructure for cooling the C-excitons. Transient optical measurements confirmed that the hot carriers from the C-excitons were effectively transferred from WS2 to CdS with an efficiency of 50% and subsequently back to the WS2 band-edge to form A-excitons over an ultrafast subpicosecond time scale, accompanied by a record high PLQY of ∼11.1% for near-resonance C-exciton excitation.

Tunable dual‐band filter based on monolayer black phosphorus

AbstractWe propose analytical and numerical modeling of a tunable electromagnetic dual‐band filter based on a periodic structure of black phosphorus (BP) discs deposited on silicon dioxide for operating in terahertz and infrared regions. Due to BP anisotropy, single operation dipole mode bands for polarization of incident wave in the armchair or zigzag directions exist. These bands correspond to different resonant frequencies. However, for another polarization, in particular, for a polarization, a double operation band appears. The dynamic control of the proposed structure can be performed by varying the electronic doping of the BP, thus changing the operating frequency of the filter. The analytical model based on the temporal coupled‐mode theory is in good agreement with the numerical simulations by COMSOL Multiphysics.

Novel chalcone-based phenothiazine derivative photoinitiators for visible light induced photopolymerization with photobleaching and good biocompatibility

Two novel visible light photoinitiators 4-(10-methyl-10H-phenothiazin-3-yl) but-3-en-2-one (PBO) and (1E,4E)-1,5-bis(10-methyl-10H-phenothiazin-3-yl)-1,4-pentadien-3-one (BMPPO) were successfully designed and synthesized. PBO and BMPPO have broad absorption range from 350 to 500 nm with the maximum absorption wavelength at 400 nm and 440 nm respectively. Three-component photoinitiating system of BMPPO/iodonium/amine was developed for free radical polymerization of acrylates. The results demonstrated that the photoinitiating system displayed rapid polymerization and high final vinyl group conversions under the irradiation of UV-LED (365 nm), blue LED (440) nm and solar light resource. Moreover, photopolymerization kinetics was studied by real-time FT-IR spectrum, the double band conversion was achieved up to 90% for BMPPO. The photocuring mechanism was identified via steady state photolysis and electron spin resonance spin-trapping experiments. The possible photoinduced mechanism of PBO and BMPPO in the presence of a co-initiator occurred through electron transfer. In addition, BMPPO possesses rapid photobleaching and good biocompatibility performance tested by photoinduced degradation and cytotoxicity experiments respectively, which exhibited that BMPPO has potential for light-color coatings and food packaging field.

Establishment of the Y-linked Dmrt1Y as the candidate sex determination gene in spotbanded scat (Selenotoca multifasciata)

Spotbanded scat (Selenotoca multifasciata) has become a valuable marine culturing fish species in the southeast coastal areas of China. Herein, sex-linked markers were developed in spotbanded scat to elucidate its genetic foundation of sex determination. Eighty-four (84) cultured spotbanded scat were randomly chosen and used to screen and test the sex-linked markers. The average weight of the female (249 g, n = 32) is significantly higher than that of the male (212 g, n = 52). The whole genome of a male spotbanded scat was sequenced using next-generation sequencing technology. Phylogenetic analysis showed that spotbanded scat diverged from its closely related species, spotted scat (Scatophagus argus) 13.1 million years ago.Three sex-linked markers (Marker-1, 2 and 3) were obtained in spotbanded scat. Marker-1 and 2 could only amplify 562 bp and 881 bp Dmrt1 specific bands in male fish, while there were no amplified bands in female fish. Marker-3 amplified a single band of 373 bp in all female, and double bands of 373 bp and specific 294 bp in male. Sequence analysis showed that the 294 and 373 bp are Dmrt1 homologous sequences. These results indicate that the spotbanded scat possesses XY sex-determination system (XX females, XY males). Two types of Dmrt1 cDNA sequences were cloned and named Dmrt1X and Dmrt1Y according to their locations on the X and Y chromosomes, respectively. The amino acid (aa) sequences coded by Dmrt1X (309 aa) and Dmrt1Y (305 aa) are highly similar (85.8%). Dmrt1Y mRNA is specifically expressed in testis, with no expression in the ovary. Hence, Dmrt1Y is male-specific and the candidate SD gene. Knowledge of genetic sex determination and the development of sex-linked markers in spotbanded scat, will promote artificial reproduction and breeding in aquaculture.

Defect band formation in high pressure die casting AE44 magnesium alloy

The characteristics of defect bands in the microstructure of high pressure die casting (HPDC) AE44 magnesium alloy were investigated. Special attention was paid to the effects of process parameters during the HPDC process and casting structure on the distribution of defect bands. Results show that the defect bands are solute segregation bands with the enrichment of Al, Ce and La elements, which are basically in the form of Al11RE3 phase. There is no obvious aggregation of porosities in the defect bands. The width of the inner defect band is 4–8 times larger than that of the outer one. The variation trends of the distribution of the inner and outer defect bands are not consistent under different process parameters and at different locations of castings. This is due to the discrepancy between the formation mechanisms of double defect bands. The filling and solidification behavior of the melt near the chilling layer is very complicated, which finally leads to a fluctuation of the width and location of the outer defect band. By affecting the content and aggregation degree of externally solidified crystals (ESCs) in the cross section of die castings, the process parameters and casting structure have a great influence on the distribution of the inner defect band.

Upconversion Nanoparticle-Integrated Bilayer Inverse Opal Photonic Crystal Film for the Triple Anticounterfeiting.

Optical anticounterfeiting plays a vital role in information security because it can be recognized by the naked eye and is difficult to imitate. Herein, a hydrophilic modified upconversion nanoparticle (M-UCNP)-integrated bilayer inverse opal photonic crystal (IOPC) film was designed in which the luminescent M-UCNPs were deposited on the surface of the optimized bilayer structure with double photonic stop bands. The structure which can modulate light to produce structural colors can also enhance the upconversion luminescence (UCL) to improve the anticounterfeiting effect synergistically. On the one hand, the reflection colors from green to blue were observed in the specular angles on the front (540-layer) of the film. Meanwhile, the scattering colors under nonspecular angles from red to blue on the back (808-layer) appeared in the natural light. On the other hand, the bilayer structure in which the 808-layer functions as a "secondary excitation source" to improve the intensity of the excitation light on M-UCNPs and the 540-layer reflects the emission light of the M-UCNPs to enhance the UCL intensity endows the film with good night vision ability. Finally, the dual-mode structural colors and enhanced UCL of the patterned film work together to realize triple anticounterfeiting in banknotes.

Double Sublaminal Band Passage Technique for Spinal Deformity Correction.

Sublaminar band fixation is a reliable way to anchor spinal rods to the vertebral column. This technique is especially useful when the anatomy precludes safe pedicle screw placement. Sublaminar bands allow for deformity correction and stabilization of the spine. One of the disadvantages of using the sublaminar band technique is the risk for neurologic injury during the passage of the band between the dura and lamina. In this article, we describe a new technique for passing sublaminar bands, i.e., the double sublaminar band passage technique. This technique decreases the number of passes against the dura, thereby decreasing the opportunity for neural injury. In addition, we present an illustrative case of an 11-year-old female with neuromuscular scoliosis who underwent a posterior spinal instrumented fusion with a hybrid screw and sublaminar band construct.

A notched UWB microstrip patch antenna for 5G lower and FSS bands

AbstractIn ASEAN countries, the fifth generation (5G) forum proposed a 5G application lower frequency band (4.5–5.5) GHz and the fixed satellite service (FSS) C‐band at (3.3–4.2) GHz. Previous research works have demonstrated that the complexity of antenna design, large size and in most of the cases, active elements that were added to antenna has made the antenna costly. Therefore, this research work focused on developing a single band notched (SBN) and double band notched (DBN) antennas by creating notched bands for 5G lower band from 4.5 to 5.5 GHz and C‐band 3.3 to 4.2 GHz applications in antenna UWB spectrum. An UWB antenna has been developed using low‐cost FR‐4 substrate with partial grounding (PG) on a rectangular patch. A single band and dual band notched UWB antennas were realized for the 5G lower band through the use of a slot at the top of the radiating patch and by adding an arc shape open loop (ASOL) on the UWB antenna. Both antennas are fabricated using the same FR‐4 substrate and tested using Vector Network Analyzer (VNA). The voltage standing wave ratio (VSWR), return loss, gain, and 2‐D radiation pattern of the test results prove that all antennas have excellent performance (compared to previous research works) in notched band and UWB band frequencies. Therefore, developed single notch and dual notch UWB antennas are proposed as good candidates for 5G lower band and C‐band notched application environment.

Modification of electronic and thermoelectric properties of InSe/GaSe superlattices by strain engineering

In recent years, superlattices and layered materials have been highlighted as potential candidates for thermoelectric applications, this thanks to their low thermal conductivity. Moreover, external applied pressure and biaxial strain can be used to enhance their properties by achieving a band engineering and electronic tuning. With this in mind, we performed an $ab$ initio based study on InSe/GaSe superlattices under biaxial strain along the layer planes. Layers of InSe and GaSe with ${D}_{3h}$ symmetry were stacked along the $c$ axis to create the superlattice. The atomic stacking along the $c$ axis is Se-Ga-Ga-Se-Se-In-In-Se, which corresponds to the space group #187. Our ab initio calculations predict the superlattice to be a semiconductor with an electronic band gap of ${E}_{g}$ = 0.54 eV. With the aim to increase thermoelectric performance, we apply positive and negative biaxial strain on the ab plane. Under compressive strain, the electronic structure evolves to an insulating behavior by increasing the band gap. When tensile strain is applied, we observe a transition towards a metallic character with a systematic reduction of the band gap. Interestingly, the semiconductor-metal transition only occurs when spin-orbit coupling (SOC) is switched off. With the inclusion of SOC, the system experiences an electronic topological transition around 3% tensile strain, with a double band gap along the $K\text{\ensuremath{-}}\mathrm{\ensuremath{\Gamma}}\text{\ensuremath{-}}M$ high-symmetry paths. We have found that for both, $n$-type and $p$-type doping, compressive strain improves the electronic figure of merit ($Z{T}_{e}$ under constant relaxation time approximation). Not only the electronic part increases thermoelectric performance, but also the lattice contribution to the thermal conductivity decreases with compressive strain.

Design and analysis of frequency reconfigurable antenna for global positioning system applications

A compact frequency reconfigurable antenna is designed and analyzed in this paper to operate with global positioning system (GPS) and worldwide interoperability for microwave access (WiMAX) applications. The designed antenna is printed on flame resistant 4 (FR4) epoxy substrate with relative permittivity is 4.3, loss tangent of 0.03 and overall substrate with ground (GND) plane dimensions of (54.6x54.6x1.6) mm3 and patch dimensions of (45x45) mm2. The antenna is designed and optimized using computer simulation technology (CST) package through series of parametric studies in order to cover the GPS, WiMAX bands with resonant frequency of 1.229 GHz, 1.575 GHz, and 3.34 GHz. Two triangular slots at the patch sides and single elliptical slot at the middle are etched for the best antenna performance. The designed antenna performs frequency re-configurability by using PIN diode switch at the inset feed to change the operating frequencies from double band operation at (1.575 and 3.34) GHz to single band at 1.229 GHz under S11 ≤-10 dB. The proposed antenna produces accepted simulation results with voltage standing wave ratio (VSWR), maximum radiation efficiency and gain of less than 2.76% and 7.035 dBi respectively.

Solvability of the Sequence Spaces Equations With Operators C<sub>a</sub>+C<sub>x</sub> = (C<sub>b</sub>)<sub>B</sub><sub>(r,s)</sub> And C<sub>a</sub>+C<sub>x</sub> = (C<sub>b</sub>)<sub>G</sub><sub>(α,α)</sub>

Given any sequence a = (an)n?1 of positive real numbers and any set E of complex sequences, we write Ea for the set of all sequences y = (yn)n?1 such that y/a = (yn/an)n?1 ? E; in particular, ca, (or s(c) a ) denotes the set of all sequences y such that y/a converges. In this paper, we solve sequence spaces equations of the form (Ex)B(r,s) = Ea, where E 2 {c0, c, `1}. Then we apply these results to the solvability of each of the (SSE) with operators ca + cx = (cb)B(r,s) and ca + cx = (cb)G(,), where B (r, s) is a double band matrix, and G(, ) is the factorable matrix with positive sequences and , that is, the triangle whose the nonzero entries are defined by [G(, )]nk = nk.

Second-Order Real Nodal-Line Semimetal in Three-Dimensional Graphdiyne.

Real topological phases featuring real Chern numbers and second-order boundary modes have been a focus of current research, but finding their material realization remains a challenge. Here, based on first-principles calculations and theoretical analysis, we reveal the already experimentally synthesized three-dimensional (3D) graphdiyne as the first realistic example of the recently proposed second-order real nodal-line semimetal. We show that the material hosts a pair of real nodal rings, each protected by two topological charges: a real Chern number and a 1D winding number. The two charges generate distinct topological boundary modes at distinct boundaries. The real Chern number leads to a pair of hinge Fermi arcs, whereas the winding number protects a double drumhead surface bands. We develop a low-energy model for 3D graphdiyne which captures the essential topological physics. Experimental aspects and possible topological transition to a 3D real Chern insulator phase are discussed.

Topological phonons and electronic structure of Li2BaSi class of semimetals

Extension of the topological concepts to the bosonic systems has led to the prediction of topological phonons in materials. Here we discuss the topological phonons and electronic structure of Li2BaX (X = Si, Ge, Sn, and Pb) materials using first-principles theoretical modelling. A careful analysis of the phonon spectrum of Li2BaX reveals an optical mode inversion with the formation of nodal line states in the Brillouin zone. Our electronic structure results reveal a double band inversion at the Γ point with the formation of inner nodal-chain states in the absence of spin–orbit coupling (SOC). Inclusion of the SOC opens a materials-dependent gap at the band crossing points and transitions the system into a trivial insulator state. We also discuss the lattice thermal conductivity and transport properties of Li2BaX materials. Our results show that coexisting phonon and electron nontrivial topology with robust transport properties would make Li2BaX materials appealing for device applications.

Theoretical exploration of mechanical, electronic structure and optical properties of aluminium based double halide perovskite.

The mechanical, electronic structure and optical properties of aluminium based double halide perovskite were calculated by density functional theory. The formation energy and elastic constant confirm the stability of the cubic perovskite materials. The materials are all ductile and suitable for flexible photovoltaic and optoelectronic devices. The band gap values vary from 0.773 eV to 3.430 eV, exactly corresponding to the range of ideal band gap values for good photoresponse. The band structure analysis shows that all the materials possess small effective mass, which indicates a good transport of carriers. And these materials have a broad energy range of optical absorption for utilization and a detector of photons. Moreover, less expensive K2AgAlBr6 were investigated for comparison with materials containing a cesium element, and according to the results, is also a candidate for photoelectronic devices due to the similar properties.

White-light emission lead-free perovskite phosphor Cs2ZrCl6:Sb3+

Obtaining phosphors with white-light emission is a promising and economical approach for phosphor-conversion light emitting diodes (pc-LEDs), but traditional single-phase white light emission phosphors are inefficient. Here a white-light-emission phosphor was prepared via a co-precipitation method by doping Sb 3+ into lead-free and vacancy-ordered double perovskite Cs 2 ZrCl 6 . X-ray diffraction, X-ray photoelectron spectroscopy, and formation energy calculations confirmed that Sb 3+ ions replaced the Zr 4+ sites in the [ZrCl 6 ] 2− octahedron. The optical properties of Cs 2 ZrCl 6 :Sb 3+ were investigated and compared with those of blank Cs 2 ZrCl 6 . The origination of the emission bands was determined according to their fluorescence spectra and decay-time at an approximate temperature of 4 K Sb 3+ -doped Cs 2 ZrCl 6 exhibited white-light emission with double emission bands at 495 and 622 nm due to the 1 P 1 → 1 S 0 and 3 P 2, 1, 0 → 1 S 0 transitions of Sb 3+ , respectively. The intensity ratios of cyan light (495 nm) and the red light emission bands (622 nm) were tunable by adjusting the Sb 3+ concentration. The red component increased with increasing Sb 3+ concentration in the present experimental range. Moreover, 10% Sb 3+ -doped Cs 2 ZrCl 6 showed the strongest emission with a photoluminescence quantum yield of approximately 78% under excitation of 333-nm light White LED devices with different correlated color temperatures were achieved by combining 1% or 10% Sb 3+ -doped Cs 2 ZrCl 6 with a 310-nm ultraviolet chip, suggesting that the synthesized samples have potential applications in white-illumination LEDs. Single-phased white emitting phosphor Cs 2 ZrCl 6 : Sb 3+ and corresponding LEDs.

Design and simulation double Ku-band Vivaldi antenna

Due to the tremendous development in the field of wireless communication and its use in several fields, whether military or commercial was proposed. A novel tapered slot Vivaldi antenna is designed and simulated at double band frequency (Ku-band) using computer simulation technology (CST) software 2020. The dimensions of the antenna are 2.3 × 1 × 0.4 mm<sup>3</sup> with a microstrip feed of 0.5 mm. The proposed antenna is improved by cutting a number of circle shapes on the patch layer in different positions. The simulation results are divided into more sections according to the number of circle shapes cutting. The results are good acceptance and make the improved Vivaldi antenna valuable in many future wireless communication applications.

A molecular dynamics study of the nonlinear spectra and structure of charged (101) quartz/water interfaces.

The relationship between the nonlinear spectra and the structure of charged (101) α-quartz/water interfaces was investigated by classical molecular dynamics simulations. The results of the simulations show that the layered organization of interfacial water is only slightly perturbed by the surface charge and the ionic strength of the aqueous phase. Molecules next to the surface, in a bonded interfacial layer (BIL), tend to direct one of their OH bonds towards the surface, while the water orientation further from the surface, in a diffuse layer (DL), is essentially isotropic. A Stern layer of solvated cations is built up already on a neutral surface and the deprotonation of silanols leads to the formation of an inner Helmholtz plane of cations directly interacting with the SiO- surface sites. A flip of the molecular orientation in the DL could be inferred from the analysis of the structural characteristics of concentrated NaCl solution in contact with a highly charged surface. The computed spectra of χ(2) susceptibility show a double band structure typical of the spectra of silica/water interfaces and the calculations reproduce the experimentally observed variation of the spectral intensity with the pH of the liquid phase. The analysis of results suggests that the behaviour stems from the interplay between the orientational and induced components of the χ(2) susceptibility of the BIL and DL. The dependence of the Im[χ(2)] spectra of the BIL on the surface charge yields the spectrum of H2O molecules directly interacting with SiO- sites. The spectrum is in excellent agreement with the experimental spectrum of the topmost water of a silica/water interface [Urashima et al., J. Phys. Chem. Lett., 2018, 9, 4109].

Molecular identification and genetic-polymorphism analysis of Fasciola flukes in Dali Prefecture, Yunnan Province, China.

This study aimed to identify species of Fasciola flukes in Dali Prefecture (Yunnan Province, China) and analyze their genetic diversity. Fasciola flukes (n=122) were collected from cattle livers in a farmers' market in Xiaguan Town, Dali Prefecture. Nucleotide sequences of ribosomal internal transcribed spacer (ITS) as well as nicotinamide adenine dinucleotide dehydrogenase subunit 1 (ND1) and mitochondrial cytochrome c oxidase subunit 1 (CO1) were amplified, sequenced, and subjected to homology analysis. The heterozygosity ratios of different ITS alleles were determined using the peak-height ratio of heterozygous loci. Multiplex PCR analysis of the nuclear protein coding gene, phosphoenolpyruvate carboxykinase (pepck), was used to identify Fasciola species. Multiple ND1 sequence alignments enabled further genetic diversity analysis of regional Fasciola flukes. Seven ITS sequences belonged to F. hepatica and 115 belonged to Fh/Fg heterozygous flukes. Sequencing analysis of heterozygous flukes revealed 11 heterozygous loci with double peaks, with significantly variable ratios among individuals. ND1 and CO1 results indicated that one specimen was identical to F. hepatica, while 121 specimens were identical to F. gigantica or contained one variable site. Multiplex PCR results for pepck showed that double bands for F. hepatica and F. gigantica were amplified from Dali Fasciola specimens; hence, they were all heterozygous. By combining ITS, ND1, and CO1 sequences with multiplex pepck PCR results, all 122 specimens were identified as Fh/Fg heterozygous Fasciola flukes. Our experimental results preliminarily confirmed a high degree of Fh/Fg heterozygosity among Fasciola flukes in the Dali area. Selecting multiple molecular markers for concurrent analysis will provide more comprehensive and accurate genetic information.

P-STAT3 is a PDC-E2 interacting partner in human cholangiocytes and hepatocytes with potential pathobiological implications

The E2 component of the mitochondrial pyruvate dehydrogenase complex (PDC) is the key autoantigen in primary biliary cholangitis (PBC) and STAT3 is an inflammatory modulator that participates in the pathogenesis of many liver diseases. This study investigated whether PDC-E2 interacts with STAT3 in human cholangiocytes (NHC) and hepatocytes (Hep-G2) under cholestatic conditions induced by glyco-chenodeoxycholic acid (GCDC). GCDC induced PDC-E2 expression in the cytoplasmic and nuclear fraction of NHC, whereas in Hep-G2 cells PDC-E2 expression was induced only in the cytoplasmic fraction. GCDC-treatment stimulated phosphorylation of STAT3 in the cytoplasmic fraction of NHC. siRNA-mediated gene silencing of PDC-E2 reduced the expression of pY-STAT3 in NHC but not in HepG2 cells. Immunoprecipitation and a proximity ligation assay clearly demonstrated that GCDC enhanced pY-STAT3 binding to PDC-E2 in the nuclear and cytoplasmic fraction of NHC cells. Staining with Mitotracker revealed mitochondrial co-localization of PDC-E2/pS-STAT3 complexes in NHC and Hep-G2 cells. In cirrhotic PBC livers the higher expression of both PDC-E2 and pY-STAT3 was observed. The immunoblot analysis demonstrated the occurrence of double bands of PDC-E2 protein in control livers, which was associated with a lower expression of pY-STAT3. Our data indicate the interaction between PDC-E2 and phosphorylated STAT3 under cholestatic conditions, which may play a role in the development of PBC.

Optimization of primer and polymerase chain reaction conditions to amplify COI locus for identification of Purnajiwa (Euchresta horsfieldii (Lesch.) Benn.) collected from Bedugul, Bali

The polymerase chain reaction (PCR) has been used for molecular research to amplify DNA fragments, especially from a small amount of genetic material. PCR has been applied for numerous researches, including for plant molecular identification. A good PCR product is dependent on good amplification of the DNA segment in optimum condition. This research was conducted to optimize the primer combination, and the annealing temperature for DNA barcoding application of Balinese rare medicinal plant (Euchresta horsfieldii (Lesch.) Benn.) collected from Bedugul. COI is a suitable primer to identify unknown species to higher taxa levels and species with high phenotypic plasticity. The range of annealing temperatures was tested to amplify the combination of five COI primers: GWSF and GWSF5 for forwarding primers and GWSR, GWSR3, and GWSR5 for reverse primers. The annealing temperature was 52, 54, 56, 58, 60°C for 30 seconds. The result showed that GWSF-GWSR, GWSF-GWSR5, GWSF5-GWSR, GWSF5-GWSR5, and GWSF5-GWSR3 produced multiple bands, the double band that cannot be cut, multiple bands, faint amplification band for GWSF5-GWSR5 and GWSF5-GWSR3, respectively. Primer combination of GWSF-GWSR3 with an annealing temperature of 52°Cproduced double bands that were available to have proceeded for sequencing. In conclusion, the combination of GWSF-GWSR3 that is annealed at 52°C produced the best amplification band. The primer combinations and conditions can be used for further identification of Purnajiwa collected from Bedugul.