Chlorophyll is not accurate measurement for algal biomass

Microalgae are key primary producers and their biomass is widely applied for theproduction of pharmaceutics, bioactive compounds and energy. Conventionally, the contentof algal chlorophyll is considered an index for algal biomass. However, this study, we estimatedalgal biomass by direct measurement of total suspended solids (TSS) and correlated it withchlorophyll content. The results showed mean chlorophyll-a equal to 1.05 mg/L; chlorophyllb0.51 mg/L and chlorophyll-a+b 1.56 mg/L. Algal biomass as 161 mg/L was measured bydry weight (TSS). In statistical t-tests, F-tests and all the tested growth models, such as linear,quadratic, cubic, power, compound, inverse, logarithmic, exponential, s-curve and logisticmodels, we did not find any discernible relationship between all chlorophyll indices and TSSbiomass. Hence, the conventional method of chlorophyll measurement might not be a goodindex for biomass estimation

The Thermodynamic and Ground State Properties of the TIP4P Water Octamer

Several stochastic simulations of the TIP4P [W. L. Jorgensen, J. Chandrasekhar, J. D. Madura, R. W. Impey, and M. L. Klein, J. Chem. Phys. 79, 926 (1983)] water octamer are performed. Use is made of the stereographic projection path integral and the Green’s function stereographic projection diffusion Monte Carlo techniques, recently developed in one of our groups. The importance sampling for the diffusion Monte Carlo algorithm is obtained by optimizing a simple wave function using variational Monte Carlo enhanced with parallel tempering to overcome quasiergodicity problems. The quantum heat capacity of the TIP4P octamer contains a pronounced melting peak at 160 K, about 50 K lower than the classical melting peak. The zero point energy of the TIP4P water octamer is 0.0348± 0.0002 hartree. By characterizing several large samples of configurations visited by both guided and unguided diffusion walks, we determine that both the TIP4P and the SPC [H. J. C. Berendsen, J. P. Postma, W. F. von Gunsteren, and J. Hermans, (Intermolecular Forces, Reidel, 1981). p. 331] octamer have a ground state wave functions predominantly contained within the D2d basin of attraction. This result contrasts with the structure of the global minimum for the TIP4P potential, which is an S4 cube. Comparisons of the thermodynamic and ground-state properties are made with the SPC octamer as well

Ab-initio study of BaTiO3 surfaces

We have carried out first-principles total-energy calculations of (001) surfaces of the tetragonal and cubic phases of BaTiO3. Both BaO-terminated (type I) and TiO2-terminated (type II) surfaces are considered, and the atomic configurations have been fully relaxed. We found no deep-gap surface states for any of the surfaces, in agreement with previous theoretical studies. However, the gap is reduced for the type-II surface, especially in the cubic phase. The surface relaxation energies are found to be substantial, i.e., many times larger than the bulk ferroelectric well depth. Nevertheless, the influence of the surface upon the ferroelectric order parameter is modest; we find only a small enhancement of the ferroelectricity near the surface.Comment: 8 pages, two-column style with 4 postscript figures embedded. Uses REVTEX and epsf macros. Also available at http://www.physics.rutgers.edu/~dhv/preprints/index.html#pad_sur

Evidence of Electromagnetic Absorption by Collective Modes in the Heavy Fermion Superconductor UBe13

We present results of a microwave surface impedance study of the heavy fermion superconductor UBe13. We clearly observe an absorption peak whose frequency- and temperature-dependence scales with the BCS gap function. Resonant absorption into a collective mode, with energy approximately proportional to the superconducting gap, is proposed as a possible explantation