The conservation of sacred sites: Sarnath, a case study

This article concerns research issues in historic conservation exemplified through a case study of a sacred site in India. It discusses the environmental qualities of Indian sacred spaces characterised by a multiplicity of religions and diffusing into the realm of the secular. An historical survey of religious architecture, myths and legends and participant observations of the many user groups are recommended as research methodologies to be followed when formulating a conservation policy framework.     

Synthesis of Nanocrystalline KTiOPO4 Powder by Chemical Method

Nanocrystalline potassium titanyl phosphate (KTiOPO₄, KTP) powder with average particle size of 25–50 nm has been synthesized from aqueous solution of titanyl chloride through coprecipitation method, using aqueous solution of potassium dihydrogen phosphate and potassium carbonate in the presence of triethanolamine (TEA) as a capping agent. In the presence of tetrapotassium pyrophosphate as a capping agent it produces the particles having average size around 70–80 nm. The same sample with average particle size ∼250 nm has also been synthesized without any capping agent. Initial amorphous phase after precipitation requires heat treatment at 500–550°C for 2 h to generate nanocrystalline powders of KTP. Formation of the KTP phase in the heat-treated samples has been confirmed through X-ray powder diffraction, thermogravimetric and differential thermal analysis, ³¹P Magic angle spinning-nuclear magnetic resonance and Fourier transform infrared spectroscopy studies, and surface area measurements.     

Hybrid Quinazoline 1,3,5-Triazines as Epidermal Growth Factor Receptor (EGFR) Inhibitors with Anticancer Activity: Design,Synthesis, and Computational Study

We report a series of hybrid quinazoline-1,3,5-triazine derivatives as EGFR inhibitors, which were synthesised and tested by using a variety of in vitro, in silico, and in vivo techniques. The derivatives were found to be active against different cancer cell lines and nontoxic against normal ones, with compounds 7 c , 7 d , 7 e , and 7 j being the most potent ones. The derivatives were also evaluated for angiogenesis inhibition potency in chicken eggs, and molecular docking and dynamics simulation studies were carried out to elucidate the fundamental substituent groups essential for their bioactivity. Additionally, a SAR study of the derivatives was performed for future compound optimisation. These studies suggested that the derivatives have a high affinity towards EGFR with favourable pharmacological properties. The most active compound ( 7 e ) was further evaluated for in vivo anticancer activity against DMBA-induced tumours in female Sprague-Dawley rats as well as its effects on plasma antioxidant status, biotransformation enzymes, and lipid profile. The study suggested that 7 e has lead properties against breast cancer and can serve as a starting compound for further development of anti-EGFR compounds.     

Formamidinium‐Based Dion‐Jacobson Layered Hybrid Perovskites: Structural Complexity and Optoelectronic Properties

Layered hybrid perovskites have emerged as a promising alternative to stabilizing hybrid organic–inorganic perovskite materials, which are predominantly based on Ruddlesden‐Popper structures. Formamidinium (FA)‐based Dion‐Jacobson perovskite analogs are developed that feature bifunctional organic spacers separating the hybrid perovskite slabs by introducing 1,4‐phenylenedimethanammonium (PDMA) organic moieties. While these materials demonstrate competitive performances as compared to other FA‐based low‐dimensional perovskite solar cells, the underlying mechanisms for this behavior remain elusive. Here, the structural complexity and optoelectronic properties of materials featuring (PDMA)FA_n–1Pb_nI_3n+1 (n = 1–3) formulations are unraveled using a combination of techniques, including X‐ray scattering measurements in conjunction with molecular dynamics simulations and density functional theory calculations. While theoretical calculations suggest that layered Dion‐Jacobson perovskite structures are more prominent with the increasing number of inorganic layers (n), this is accompanied with an increase in formation energies that render n > 2 compositions difficult to obtain, in accordance with the experimental evidence. Moreover, the underlying intermolecular interactions and their templating effects on the Dion‐Jacobson structure are elucidated, defining the optoelectronic properties. Consequently, despite the challenge to obtain phase‐pure n > 1 compositions, time‐resolved microwave conductivity measurements reveal high photoconductivities and long charge carrier lifetimes. This comprehensive analysis thereby reveals critical features for advancing layered hybrid perovskite optoelectronics.     

A new chemical route for the preparation of fine ferrite powders

Precursors to MFe₂O₄ [spinels ferrites; where M = Ni(II), Co(II) and Zn(II)] have been prepared by the evaporation of polyvinyl alcohol added mixed metal nitratesolution, in presence and absence of urea. Theprecursor materials have low ignition temperature and are spontaneously combustible at low temperatures (250°C to 400°C). The heat liberated through the process is sufficient for the crystallization of the desired ferrite phase. The urea added process resulted in finer, superparamagnetic particles (12–17 nm) compared to the process without urea (particle size 25–30 nm). The ultrafine ferrite powders obtained have been characterized by X-ray powder diffraction (XRD), thermal gravimetry (TG), differential scanning calorimetry (DSC), infrared spectroscopy (IR), transmission electron microscopy (TEM) and room temperature magnetic measurement studies.     

Effect of citric acid on properties of CeO2 films for electrochromic windows

An alcohol based sol–gel process involving cerium chloride heptahydrate and citric acid in different mole ratios has been employed for the deposition of CeO₂ films. The structural, electrochemical, and optical properties of the films have been investigated using a wide range of techniques. Differential thermal analysis has shown the onset of crystallization of CeO₂ at 389 °C. The addition of an additive (citric acid) to the precursor sol has led to homogeneity and also a reduced ion storage capacity in the films. This observation emphasizes on the use of optimum content of the citric acid such that the films are suitable in terms of transparency as well as uniformity characteristics and also exhibit good electrochemical response. As is evidenced by the SEM study, the degree of polycrystalline grain formation in the citric acid derived films is observed to be less. The XPS results have confirmed the presence of Ce⁴⁺ state in the films. The optically passive behavior of the films is affirmed by their negligible transmission modulation upon Li ion insertion and extraction. A higher proportion of citric acid has also resulted in a reduced porosity and diminished crystallite size of the cerianite phase. The effect of the CeO₂ films on the switching kinetics of the tungsten oxide (WO₃) films has revealed an increase in the coloration time of the latter with the diminished crystallite size of CeO₂ nanograins in the former.     

Bulk magnetic properties of CdFe<Subscript>2</Subscript>O<Subscript>4</Subscript> in nano-regime

Cadmium ferrite particles have been synthesized using co-precipitation technique followed by a low temperature (600°C) annealing in a time scale much shorter than reported in literature. Incorporation of sodium chloride during annealing helps to form a single phase spinel structure with a final particle size of around 50 nm. Even at such a short length scale we observe the overall magnetic properties to be similar to those of the bulk. The observed magnetic properties can be explained on the basis of an anti-ferromagnetic core with a shell containing ‘ferromagnetic-like’, but canted spin structure.     

Temperature effects in silicon solar cells

The temperature variation of the relative spectral response RSR, short circuit current I_sc and open circuit voltage V_oc is measured and the results are theoretically discussed. The RSR at wavelengths larger than the peak wavelengths always increases with temperature. The observed increase is found to agree with theory when temperature variation of the absorption coefficient of light and of L_n the carrier diffusion length in the base is taken into account properly. The temperature variation of short wavelength RSR depends on S, the surface recombination velocity and $\text{L}{}_{\mathrm{p}}\text{d}\text{, L}{}_{\mathrm{p}}$ is the carrier diffusion length in the diffused layer and d is the junction depth. If S is small and $\text{L}{}_{\mathrm{p}}\text{d}$ is large, the RSR is practically independent of temperature. On the other hand if S is large and/or $\text{L}{}_{\mathrm{p}}\text{d}$ is small, the RSR decreases as the temperature increases.A new relation between L_n, d and the peak position of RSR is derived. The observed temperature shift in the peak position agrees well with that predicted by this relation.The temperature increase of I_sc and decrease of V_oc are different for AM0 and AM1 illuminations. The observed differences can be explained at least qualitatively on the basis of the results obtained in this paper.     

Decadence, mourning and revolution: facets of the 19th-century landscape of Lucknow, India

Gardens played a significant role in the evolution of the city of Lucknow in the last quarter of the 18th century and the first half of the 19th century. In a period of eight decades from 1775, when it became the court of Avadh province, the city experienced a period of efflorescence in art, architecture, and garden design unmatched in its later history. This era was abruptly terminated by the mutiny or first war of independence in 1857, bringing colonial rule in its wake. Gardens in this brief period can be seen as settings of decadence, theatres of mourning, and arenas of rebellion. The paper explores these three themes interwoven in the landscape narrative.     

Inorganic nanocomposites for the next generation photovoltaics

Photovoltaic is an attractive alternative of conventional energy source, but for the limitations of present materials and technology, we need to find out cost effective and environmentally stable new materials. We have synthesized a novel nanocomposite, named titania–germanium (TiO₂–Ge). TiO₂–Ge is a thermodynamically stable material. Ge nanodots are dispersed in the TiO₂ matrix of the nanocomposites. Bohr radius of Ge is relatively large, 24.3 nm, therefore, it is easy to vary the size of Ge nanodots, and consequently the properties (structural, optical and electrical) of TiO₂–Ge can be tailored in a wide range just by varying the size and density of Ge nanodots. TiO₂–Ge with size gradient of Ge nanodots is a promising active layer of the next generation solar cells.