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Copper zinc sulfide (CuZnS) is an upcoming photovoltaic material. The room temperature photoluminescence (PL) study of thin films of this material synthesized using automated chemical spray pyrolysis (CSP) is reported. The PL spectra from CuZnS comprises of a broad emission constituted by multiple peaks. In this work, ratio of intensities of peaks around 660 nm and 550 nm (I660/I550) as a function of copper ion concentration and deposition temperature is studied. The nature of spectra at lower and higher deposition temperatures seem to be significantly different. Existence of mutually interacting but independent Cu and Zn related phases are evident from PL spectra. Lower deposition temperatures favor copper related phases and higher deposition temperatures promote zinc related emissions. PL technique is used as a non-destructive tool in bringing out the potential of the material to be used as an absorber and p-type window layer in solar cell.

This paper reports on room temperature photoluminescence (PL) studies on copper zinc sulfide (CuZnS) films that are deposited through chemical bath deposition (CBD) technique. The PL emission is a broad emission in greenish red region of the spectra. PL spectroscopy is employed as a non-destructive tool to identify copper rich and copper deficient areas of the film. The emissions attributing to copper related and zinc related defects are well distinguished in copper rich and zinc rich films. PL also serves as a contactless method to determine the uniformity of the films. Structural and morphological analysis of the film gives further confirmation of the results obtained from PL analysis.

Duggleby (2018) has made a numerical analysis of some aspects of the wide range of phenomena we reviewed in Steele et al. (2018) and asserted " .that panspermia as proposed by Steele et al. (2018) is extremely implausible.” It seems to us that Duggleby has based his viewpoint on a quite narrow and specific model of Panspermia which he supposes to be active in the cosmos. Here we address both his conclusions and his numerical analysis. Our response therefore will be at two levels, his specific analysis and his general conclusions. In the specific section below we show that while Duggleby's numerical analysis appears in part correct it is, in the final analysis, quite irrelevant to Cosmic Panspermia. In the general response which follows we address his unsupported conclusion throughout his critique, namely that … " none of the examples mentioned by Steele et al. (2018) is decisive enough to allow no other explanation."

We review the salient evidence consistent with or predicted by the Hoyle-Wickramasinghe (H-W) thesis of Cometary (Cosmic) Biology. Much of this physical and biological evidence is multifactorial. One particular focus are the recent studies which date the emergence of the complex retroviruses of vertebrate lines at or just before the Cambrian Explosion of ∼500 Ma. Such viruses are known to be plausibly associated with major evolutionary genomic processes. We believe this coincidence is not fortuitous but is consistent with a key prediction of H-W theory whereby major extinction-diversification evolutionary boundaries coincide with virus-bearing cometary-bolide bombardment events. A second focus is the remarkable evolution of intelligent complexity (Cephalopods) culminating in the emergence of the Octopus. A third focus concerns the micro-organism fossil evidence contained within meteorites as well as the detection in the upper atmosphere of apparent incoming life-bearing particles from space. In our view the totality of the multifactorial data and critical analyses assembled by Fred Hoyle, Chandra Wickramasinghe and their many colleagues since the 1960s leads to a very plausible conclusion - life may have been seeded here on Earth by life-bearing comets as soon as conditions on Earth allowed it to flourish (about or just before 4.1 Billion years ago); and living organisms such as space-resistant and space-hardy bacteria, viruses, more complex eukaryotic cells, fertilised ova and seeds have been continuously delivered ever since to Earth so being one important driver of further terrestrial evolution which has resulted in considerable genetic diversity and which has led to the emergence of mankind. ispartof: PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY vol:136 pages:3-23 ispartof: location:England status: published

ZnO sensors were fabricated from flower like nanorods prepared by hydrothermal method. Thick films of pure ZnO were prepared for gas sensing application. Different sample characterization techniques have been employed, such as, XRD, SEM, FESEM, TEM etc. XRD pattern ZnO samples reveal hexagonal wurtzite structure of the sample. The average crystallite size for ZnO sensor was found to be 31 nm. The sensitivity, operating temperature, response time and recovery time of the ZnO – based gas sensor were investigated in terms of the response to reducing gas NH3. The lowest detection limit for ammonia gas was about 5 ppm at an operating temperature of 230°C.

Single crystals of potassium sulfamate are grown by the method of slow evaporation at constant temperature. AC electrical conductivity of potassium sulfamate is measured in the temperature range 300–430 K and in the frequency region between 100 Hz and 3 MHz along the a, b and c-axes. Complex impedance spectroscopy is used to investigate the frequency response of the electrical properties of the potassium sulfamate single crystal. Temperature variation of AC conductivity and dielectric measurements show a slope change around 345 K for both heating and cooling run and this anomaly is attributed as phase transition, which is well supported by the DSC measurements. Value of loss tangent in the temperature region 330–400 K is found to be very low. Activation energies for the conduction process are calculated along the a, b and c-axes. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

DC electrical conductivity studies were carried out along the three crystallographic axes for tripotassium sodium dichromate (K3Na(CrO4)2 or KNCr). Earlier studies of phase transition in this crystal show successive phase transitions at 239 K and 853 K. In this paper we report the dc electrical conductivity measurements in the temperature region 303–430 K along the crystallographic axes. An anomaly in conductivity was obtained around 326 K along both the axes. This may be attributed as due to a newly observed phase transition in the crystal. DSC taken for the sample also shows exothermic peak supporting the occurrence of newly observed phase transition.

Single crystals of sulfamic acid have been grown by the method of slow evaporation at constant temperature. DC electrical conductivity was measured in the temperature range 300 - 440 K along a, b and c-axes. Conductivity measurements show slope change near 330 K and 410 K. The slope change observed around 330 K may be attributed as due to a phase transition which has been well supported by the DSC and DTA measurements. Slope change observed around 410 K is attributed as the onset of the thermal decomcoposition as evidenced by TGA curve. TGA studies show the crystal is very stable up to 440 K. Activation energies for the conduction process are calculated for all measured crystallographic directions. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Elastic anomalies in Potassium Sulphamate, (KNH 2 SO 3 ), above room temperature were detected from temperature variation of elastic constants measured by ultrasonic Pulse Echo Overlap technique. Potassium Sulphamate has been reported to be a ferroelectric and piezo electric material. The elastic constants C 11 , C 44 , C 55 and C 66 have exhibited weak anomalies around 350 K. The DC conductivity measurement along a , b , and c axes also supports this conclusion.

The double sulfate family (ABSO4), where A and B are alkali metal cations, is the object of great interest owing to the complexity and richness of its sequence of phase transition induced by temperature variation. A new sulfate salt characterized by the presence of water molecule in the unit cell with the chemical formula, Li2Na3(SO4)2⋅6H2O (LSSW), was obtained. The ultrasonic velocity measurement was done with pulse echo overlap technique (PEO). All the six second order elastic stiffness constants, C11 = C22, C33, C44 = C55, C12, C14 and C13 = C23 are reported for the first time. The anisotropy in the elastic properties of the crystal are well explained by the pictorial representation of the polar plots of phase velocity, slowness, Young's modulus and linear compressibility in a-b and a-c planes.

DC electrical conductivity studies were carried out along the three crystallographic axes for Tripotassium sodium diselenate (K3Na(SeO4)2 or KNSe). Earlier studies of phase transition in this crystal show successive phase transitions at 334 K, 346 K, 730 K, and 758 K. In this paper we report the dc electrical conductivity measurements in the temperature region 303 K – 430 K along a, b and c – axes. An anomaly in conductivity was obtained around 341 K and another one around 333 K. These can be attributed as due to phase transitions in this crystal. A strong anomaly also has been observed along the c-axis and comparatively week one along a and b axes around 395 K for the first time. This can be due to newly observed phase transition in the crystal. DSC taken for the sample also shows endothermic peak supporting the occurrence of newly observed phase transition. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Cochin University of Science and Technology,Mahatma Gandhi University & Catholicate College, Pathanamthitta

Phase transition studies of sodium doped Lithium potassium sulphate, Li K 0.9 Na 0.1 SO 4 , crystal by ultrasonic Pulse Echo Overlap [PEO] technique are reported for the first time. The crystal shows pyroelectric, ferroelectric and electro optic properties. It is simultaneously ferroelastic and superionic. This study reported elastic properties and checked the effect of doping on suspected phase transition around 333 K as reported by Brillouin and thermal expansion studies. The transverse modes C 44 and C 66 show elastic anomalies around 333 K.

In this report, the effect of incorporation of metallic tin (Sn) on opto-electronic properties of ZnO thin films is presented. ZnO thin films were deposited through ‘automated chemical spray pyrolysis’ (CSP) technique; later different quantities of ‘Sn’ were evaporated on it and subsequently annealed. Vacuum annealing showed a positive effect on crystallinity of films. Creation of sub band gap levels due to ‘Sn’ diffusion was evident from the absorption and PL spectra. The tin incorporated films showed good photo response in visible region. Tin incorporated ZnO thin films seem to satisfy the desirable criteria for buffer layer in thin film solar cells.

Elastic properties of Potassium Sulphamate single crystal with chemical formula, KNH2SO3 are studied by ultrasonic Pulse Echo Overlap (PEO) technique. It crystallizes in the orthorhombic symmetry with space group Pbcm The study involves measuring ultrasonic velocity in the crystal in certain specified crystallographic directions; all the nine elastic stiffness constants, compliance constants and Poisson’s ratios are evaluated. The polar plots in a – b , a – c and b – c planes of Phase velocity, Slowness, Young’s modulus and Linear compressibility reveal the anisotropy in elastic properties.

Red rain cells are the microscopic biological cells which appear mixed in rain water in large quantity imparting visibly red color to the rain water in a strange event called red rain phenomenon. Our study of this phenomenon which happened in Kerala, India in 2001 has shown that the origin of these cells is possibly extraterrestrial. These cells are not so far successfully identified as any organism known on earth. The cells have unusual property like ability to reproduce at extreme high temperature and the colorless daughter cells cultured from the red cells show unusual autofluorescence characteristics. In this paper we report the autofluorescence characteristics of the original red rain cells. High resolution fluorescence microscopy is employed to study the fluorescence images of the cells under UV-Visible excitation. The results are discussed.

The red rain microbes, which caused red rain phenomenon in Kerala, India, exhibit many characteristics much different from conventional microorganisms. Previous study indicates that these microbes are possibly of extraterrestrial origin. Their ability to multiply at extreme high temperature of 300°C and the unusual autofluorescence of their biomolecules are some of their extraordinary properties. Their molecular composition is yet to be identified. In this paper we report the growth pattern of these novel microbes at temperatures below 100°C as a minimal approach to show their biological nature. Automated turbidity measurement of the cell culture indicate standard microbial growth curve. Increase in the cell population is faster at higher temperatures. Details of this investigation and results are discussed.

We have shown that the red cells found in the Red Rain (which fell on Kerala, India, in 2001) survive and grow after incubation for periods of up to two hours at 121 oC . Under these conditions daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure to 121 oC. No such increase in cells occurs at room temperature, suggesting that the increase in daughter cells is brought about by exposure of the Red Rain cells to high temperatures. This is an independent confirmation of results reported earlier by two of the present authors, claiming that the cells can replicate under high pressure at temperatures up to 300 oC. The flourescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectangle planetary nebula and other galactic and extragalactic dust clouds, suggesting, though not proving, an extraterrestrial origin., Comment: 11 pages 10 figures SPIE Conference 7819 Instruments, Methods, and Missions for Astrobiology XIII Aug. 3-5 2010 San Diego, Ed. Richard B. Hoover

A number of cases of yellow colored rain occurred in Kerala, India in July-August 2001 along with the red rain phenomenon. Recently during the end of July 2008 a few cases of yellow colored rain again occurred in Kerala and during the same time, unusual rain, termed as "blood rain" occurred in Bagado, Colombia. In this paper we show that the yellow rain and red rain can have a common origin. The yellow rainwater also exhibits the same unusual autofluorescence reported earlier for the cultured red rain microbes. Reasons for considering extraterrestrial origin for these colored rains are discussed.

The red cells found in the red rain in Kerala, India are now considered as a possible case of extraterrestrial life form. These cells can undergo rapid replication even at an extreme high temperature of 300 deg C. They can also be cultured in diverse unconventional chemical substrates. The molecular composition of these cells is yet to be identified. This paper reports the unusual autofluorescence characteristic of the cultured red rain cells. A spectrofluorimetric study has been performed to investigate this, which shows a systematic shift of the fluorescence emission peak wavelength as the excitation wavelength is increased. Conventional biomolecules are not known to have this property. Details of this investigation and the results are discussed.

A red rain phenomenon occurred in Kerala, India starting from 25th July 2001, in which the rainwater appeared coloured in various localized places that are spread over a few hundred kilometers in Kerala. Maximum cases were reported during the first 10 days and isolated cases were found to occur for about 2 months. The striking red colouration of the rainwater was found to be due to the suspension of microscopic red particles having the appearance of biological cells. These particles have no similarity with usual desert dust. An estimated minimum quantity of 50,000 kg of red particles has fallen from the sky through red rain. An analysis of this strange phenomenon further shows that the conventional atmospheric transport processes like dust storms etc. cannot explain this phenomenon. The electron microscopic study of the red particles shows fine cell structure indicating their biological cell like nature. EDAX analysis shows that the major elements present in these cell like particles are carbon and oxygen. Strangely, a test for DNA using Ethidium Bromide dye fluorescence technique indicates absence of DNA in these cells. In the context of a suspected link between a meteor airburst event and the red rain, the possibility for the extraterrestrial origin of these particles from cometary fragments is discussed., Comment: 18 pages, 15 figures, accepted for publication in Astrophysics and Space Science

Vicker's microhardness study of (100), (010) and (001) faces of a non-linear optical crystal sulfamic acid have been reported. Single crystals of sulfamic acid have been grown by slow evaporation method. The load dependence of the Vickers microhardness of sulfamic acid crystal were investigated and analyzed from the stand point of various theoretical models. Crystal samples in a, b and c-axes exhibit reverse indentation effect which is best described by Meyer's law, Hays-Kendall's approach and proportional specimen resistance (PSR) models. The negative values of load dependent quantities in Hays-Kendall's approach and PSR model suggest that the origin of indentation size effect is associated with the process of relaxation of indentation stresses.