Service robots create a touchless experience for travellers; therefore, this research aims to conduct a systematic literature review (SLR) of service robots in the tourism and hospitality sector. ...This study used the Scientific Procedures and Rationales for Systematic Literature Reviews (SPAR-4-SLR) approach for reviewing the articles. One hundred eighteen articles are selected for the final review. A thematic analysis divided the articles into three themes and nine sub-themes. For establishing the future research directions Theory, Methodology, and Context (TMC) framework was used and forty-one future research questions are proposed. The study provides various research implications concerning theory and practical perspective. Different management theories are linked with future research questions. Few review papers discussed the service robot in the context of the tourism sector, but none of these studies used the SPAR-4-SLR and TMC framework. This study comprehensively reviews the articles and provides potential future research directions.
Amniotic band syndrome (ABS) has been known since ancient times. Descriptions in modern medicine have occurred since the mid-nineteenth century. The association of the amniotic band syndrome with ...tethered cord is rare. It was generally thought to be incompatible with life. Of late, with better imaging, there have been case reports of amniotic bands causing cord tethering in neurosurgical literature, but its association with limited dorsal myeloschisis has hitherto not been described. We report a case of amniotic band syndrome (ABS) associated with a cervical limited dorsal myeloschisis (LDM) in a child of 2 and a half years old. The management of LDM in ABS is essentially the same as in isolated cases
This paper presents the dimensional synthesis of a 3-RPS (revolute–prismatic–spherical) parallel manipulator according to the limitation on the range of motion of the spherical joints. The synthesis ...of the manipulator is carried out using a hybrid optimization method called GA–simplex method. The architectural parameters of the manipulator are determined by considering the design problem as an optimization problem. The hybrid method first carries out the global search for the solution using genetic algorithm (GA) and then applies the simplex method for the local search. While determining the dimensions of the fixed platform, the physical constraints such as limitation on the range of motion of the spherical joints are considered to make the design practical. The procedure presented can be applied to synthesize the manipulator for any number of positions. A numerical example for the synthesis with 10 positions is presented.
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•Co-precipitation method is used to synthesize Co-Sm co-doped ZnO sample.•The crystallinity of the sample enhanced on adding Co dopant into ZnO matrix.•Prismoid structure is observed ...for CZ and CSZ1 samples.•CSZ1 sample showed strong superparamagnetic with weak ferromagnetic ordering.
The current study illustrates the impact of defects on magnetic behaviour of the ZnO based samples. We examined the structural, luminescent, and magnetic properties of Co-Sm co-doped ZnO nano powder synthesized using the co-precipitation method. X-ray diffraction (XRD) and a Raman study were carried to understand the structural properties. The XRD results showed that all the prepared samples exhibited wurtzite phase with no impurity peaks. The same was reflected in the Raman study along with disorder induced band indicating enhanced defects sites on doping and co-doping. The presence of defects in the prepared samples was further confirmed using photoluminescence characterization. The morphological study confirms the prismoid structures in Co doped, and Co and Sm co-doped ZnO samples. A vibrating sample magnetometer (VSM) was used to investigate the magnetic properties of the samples at room temperature, which showed the coexistence of superparamagnetic and weak ferromagnetic ordering in doped/co-doped samples. The formation of defects in prismoid structures enhanced the magnetic behaviour of the samples. The evolution of ferromagnetic ordering in doped/co-doped samples due to defect states was discussed in detail.
We synthesized a novel water-soluble porphyrin THPP and its metalated derivative Zn-THPP having excellent triplet excited state quantum yields and singlet oxygen generation efficiency. When compared ...to U.S. Food and Drug Administration approved and clinically used sensitizer Photofrin, THPP showed ca. 2-3-fold higher in vitro photodynamic activity in different cell lines under identical conditions. The mechanism of the biological activity of these porphyrin systems has been evaluated through a variety of techniques: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, comet assay, poly(ADP-ribose)polymerase (PARP) cleavage, CM-H(2)DCFDA assay, DNA fragmentation, flow cytometric analysis, fluorescence, and confocal microscopy, which confirm the apoptotic cell death through predominantly reactive oxygen species (ROS). Moreover, THPP showed rapid cellular uptake and are localized in the nucleus of the cells as compared to Hoechst dye and Photofrin, thereby demonstrating its use as an efficient sensitizer in photodynamic therapy and live cell NIR nucleus imaging applications.
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•The synthesis of the pure and Mg-doped ZnO nanoparticles was done using the chemical co-precipitation method.•The photocatalytic degradation study of pure and Mg-doped ZnO with ...Methylene Blue (MB) dye solution was done by studying the optical absorption spectra of MB dye solution at different time intervals using the UV–Vis spectrophotometer.•Photoluminescence spectroscopy (PL) to study the defect levels and anion vacancies introduced by doping and the subsequent enhancement of electronic properties.•Theoretical investigation of the band structure of the doped and the undoped system done using Density Functional Theory (DFT) calculations.
Currently, the world needs low-cost and high-performance photocatalysts to degrade the carcinogenic pollutant from water. In the present work, a modified ZnO matrix using Mg as a dopant has been reported with theoretical and experimental results to highlight its structure and functions on photocatalytic activity. A versatile chemical co-precipitation technique was employed to get the Mg-ZnO nanostructures. Structural characterization by high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) studies show the formation of hexagonal wurtzite structures with no impurity phases. Optical studies confirm the formation of ZnO with intrinsic defects after modifying the matrix, which agrees with the band structure calculations computed using density functional theory (DFT). Mg-modified ZnO introduced intrinsic defects like vacancies and interstitials that have a great impact on applications like photocatalysis. Based on these supporting results we employed prepared samples for dye degradation, which performed well (80% degradation efficiency) in a short period of UV irradiation. This could be a promising technology for environmental remediation.
We have grown ZnS (zinc sulfide) nanoparticles (NPs) by hydrothermal and microwave (MW) heating method and a comparative study on the physical properties was carried out. Zinc acetate dihydrate (ZAD) ...and thioacetamide (TA) were used as Zn and S precursors, respectively. X-ray diffraction (XRD) and selected area electron diffraction (SAED) pattern revealed the cubic structure for ZnS and nanocrystalline nature of the samples. The careful observation of the XRD patterns of the samples grown by hydrothermal and microwave heating method indicate that microwave-synthesized ZnS (ZnS–MW) samples were strained compared to those grown by conventional hydrothermal methods. Uniform sized smaller nanoparticles were formed during microwave irradiation in a much shorter time. UV–Vis absorption spectra indicated quantum confinement effect. The emission peaks in photoluminescence spectra indicate the presence of various point defects in the samples. In the microwave synthesized sample, nucleation and growth process of the ZnS crystallites are very quick, leading to the formation of defects. The dielectric studies of both types of the samples show a typical behavior of polycrystalline semiconducting material. Under the applied A.C. fields, the conduction phenomena provide sufficient evidence for the electronic hopping between localized sites. Lower values of activation energy obtained for both dipolar relaxation and DC conductivity in the case of microwave synthesized sample indicate the applicability of such materials in various switching applications.
The present work focuses on Raman and photoluminescence spectroscopic study of spin coated Nd doped titania thin films annealed at 350 and 450 °C. For all the samples, the penetration depth of laser ...was evaluated to be about 300–350 nm. The lifetime of phonon was in the range 0.46–0.52 ps for different samples and its variation is discussed in detail. Photoluminescence (PL) spectra of Nd doped titania revealed the influence of dopant concentration on defect sites and strong emission in near infrared (NIR) region confirms Nd doping in titania matrix. The effect of Nd doping on photocatalytic behavior of titania films was studied by degrading methyl orange (MO) under UV light. The Nd doped titania thin films enhance the photocatalytic activity as compared to pristine titania. The enhancement in efficiency is correlated to the formation of surface defects.
Energy transformation mechanism between titania and Nd, causing Nd related emission. Display omitted
•A Nd doped titania thin film photocatalyst was prepared using spin coating method.•The Raman scattering study illustrates influence of Nd dopant on structural properties of the films.•The origin of Nd related emission in infra-red region confirms the doping of Nd in titania matrix.•The photocatalytic activity was found to be high for 0.4 at% Nd doped sample annealed at 450 ֯C.
Zinc oxide (ZnO) thin films were deposited on glass substrates through spin coating technique. Zinc acetate dihydrate, monoethanolamine and 2-methoxyethanol were used as the starting material, ...stabilizer and solvent, respectively. The effect of precursor concentration on the structural, optical and electrical properties of ZnO thin films is investigated. The X-ray diffraction studies reveal that all the films are polycrystalline in nature with preferred (002) orientation with crystallite size ranging from ~25 to 32 nm. Atomic force microscopy images infer the columnar growth of the films. From the optical measurements it was found that there was a marginal decrease in the band gap energy with increase in molarity up to 0.7 M. Optical constants and thickness of the films were found with the help of Swanepoel envelope method and were verified through ellipsometric measurements. Electrical resistivity of the grown films was found to be in the range 29–244 Ω cm, with a lowest value obtained for the films grown at 0.7 M. Carrier concentration of the grown films has also followed a similar trend. On the other hand, the Hall effect mobility (~400 cm
2
/Vs) was highest for the films grown at 0.7 M. Such high values make these films potential candidates for photovoltaic and display applications.
•Fundamental, structure and extraction of Chitosan is properly discussed.•Explain role of deacetylation degree in properties.•Various derivatives and their synthesis methods and recent literature ...available for chitosan derivatives based nanocomposites is discussed.•Biomedical application such as tissue engineering, wound healing and drug delivery in vivo and in vitro are described.•Key challenges, future perspectives and chitosan based commercial products in market are discussed.
Chitosan is known to possess excellent properties such as biodegradability, biocompatibility, antimicrobial activity and less toxicity due to which it has applications in various fields. Another important benefit of chitosan is that it can be processed into different forms like membranes, sponges, gels, scaffolds, microparticles, nanoparticles, nanofibers and 3D printed constructs. For these reasons, chitosan has found to be highly advantageous in biomedical field. The reactive amino and hydroxyl groups in its chemical structure make it an ideal candidate for a wide range of applications. However, the compromising mechanical strength of chitosan limits its applications, which can be improved using nanotechnology. Chitosan based nanocomposites have gained significant attention in the last two decades. In the present review, we discuss the advantages of chitosan based nanocomposites for biomedical applications majorly tissue engineering, wound dressing and drug delivery. This review emphasizes on recent findings concerning the use of innovative chitosan based nanocomposites in biomedical applications. It also covers brief overview of chitosan, its extraction, structure and modifications and its in vitro and in vivo efficacy. Then, a detailed summary of recent progress in biomedical applications are presented. Current chitosan based nanocomposite as product in market, future perspectives and challenges are also discussed.
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