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Table 6 Results and analysis in orthogonal test L9(34) Number Calcination temperature Degradation time Lanthanum doping ratio Amount of catalyst Photo-degradation rate ºC min % mg % A B C D 1 1 1 1 1 6.620 2 1 2 2 2 19.100 3 1 3 3 3 7.836 4 2 1 2 3 16.426 5 2 2 3 1 9.619 6 2 3 1 2 29.716 7 3 1 3 2 4.838 8 3 2 1 1 5.486 9 3 3 2 3 16.021 K1 11.185 9.295 13.941 10.753 K2 18.587 11.402 17.182 17.885 K3 8.782 17.858 7.431 9.916 RD 9.805 8.563 9.751 7.969 The experimental program in accordance with Table 6 results showed: according to different conditions of lanthanum doped ultra-fine TiO2 was prepared are white powders, the factors affecting photo-degradation rate followed by a significant degree of catalyst calcination temperature (A) > lanthanum doping ratio (C) > photocatalytic degradation time of methyl orange (B) > amount of catalyst (D).

Reported results reveal that the preparation route has a significant influence on the morphology of the LDHs, giving rise to solids consisting of compact agglomerates of non-porous grains, which are poorly crystalline, or solids with presence of platelets, many of which are hexagonal in form, typical of well-crystallized hydrotalcite-type compounds [43].
Catalytic performance In the recent years an important number of review articles devoted to the use of heterogeneous catalysts for the synthesis of biodiesel have been published, which demonstrates that this topic constitutes a very active research field [32,64-67,71-79].

As a result, higher densities of extended defects such as dislocations and grain boundaries are much easier to generate as these growth islands from different nucleation sites coalesce.
The semiconductor laser has a number of unique advantages when compared against other coherent light sources, namely high efficiency, robustness, high speed, higher reliability, and potentially lower cost.
Hence, no wonder that only a small number of research efforts have been undertaken on UV LDs, and consequently only a few works have been published so far [158-162, 163 ].
There are now some new materials and improved structures with better quality, and a number of recent results seem to be promising in this regard.

Rutile is the stable phase at high temperatures, but anatase and brookite are common in fine grained (nanoscale) natural and synthetic samples [3, 4, 14-16].
To improve these parameters, a number of synthetic strategies have been adopted by the researchers.
Titania-silica mixed oxides have a large number of applications in catalysis, either as catalyst by themselves or as catalyst support [32-34].
TiZr denote the zirconium titanium mixed oxide and the number indicates different mole of hydrazine (N) used. 2.4 Titania-tungsten oxide materials Titania-tungsten oxide system is studied by several researchers due to some inherent interesting properties of WO3 in combination with titania.

Fig. 2: Radiative recombination having transitions between (i) (a) intrinsic band and acceptor level (b) intrinsic band and donor level, (ii) band to band transitions, (iii) donor to acceptor level, and (iv) excitonic recombination via impurity centers Photoluminescence process can involve non-radiative transitions which can be described as: (i) generation of phonons due to thermal vibrations, (ii) recombination at surface states, dislocations, grain boundaries, etc., (iii) all the defect sites may not act as recombination centers to allow the carriers to recombine radiativly, (iv) auger process in which the energy lost by the captured carriers excites another nearby carrier in the crystal and gives rise to non-radiative transition.
This offers simple, clean, fast, efficient, and economic technique for the synthesis of a large number of organic molecules.
The degree of crystallization also increases after the addition of nanorods in PVA which is due to the increase in number of hydrogen bonds.
(v) Sensors: Chemically sensitive materials and gas sensors made from polymer nanocomposites have attracted great attention due to their number of industrial and technological applications such as food packaging, electronics, security, and chemical industry.

The XRD and scanning electron microscopy (SEM) analyses revealed that the structure of the prepared ZnPNPs was the monoclinic phase with an average grain size of around 15 nm and the particles were highly agglomerated with irregular morphology.
Besides, both techniques utilize a variety of capping agents, a large number of toxic chemicals and produce harmful by-products, which could be detrimental to humans and the environment [116, 117].

Moreover, conductive BaTiO3 single crystals and grains exhibit a clear ferroelectric phase transition, which is manifested by the divergence of the dielectric permittivity at TC, in a similar manner to pure BaTiO3 [32, 46].
A question is “why has not even a trace of intrinsic screening been detected by tremendous number of researches on 180o domains in the past?”

When a solid-state reaction is applied to prepare aluminates, boron oxide (B2O3) is used as a flux to accelerate grain growth [139].
The absorption and emission bands of activators are controlled by changing the crystal field or the covalence depending on site size, site symmetry and coordination number of activator ions [243].

Massive number of plant species available in nature, with broad range of phytochemicals still remains unexplored for the NP synthesis [15, 50, 56, 62-67].
NPs of Au, Ag, Au-Ag, Pd, Pt, Cu, Fe, Ti, In, Se, Zn have been synthesised using plant portions that are utilized as vegetables, grains, spices, fruits, medicinals and other foodstuffs.
At pH 5 the functional groups acquire an overall negative charge, which averts the binding of negatively charged Au(III) thus generating few number of NPs.
Moreover, as the extract concentration with respect to Au(III) was increased, the size of the triangular and hexagonal particles decreases and the ratio of the number of spherical NPs to triangular/hexagonal particles also increased.
iv) The work done so far is largely confined to nanoparticles of gold, silver, platinum, and palladium while a very vast number of elements and their compounds are yet to be explored.