Optical Signature of a Crossover from Mott- to Slater-Type Gap in Sr_{2}Ir_{1-x}Rh_{x}O_{4}.

With optical spectroscopy we provide evidence that the insulator-metal transition in Sr_{2}Ir_{1-x}Rh_{x}O_{4} occurs close to a crossover from the Mott- to the Slater-type. The Mott gap at x=0 persists to high temperature and evolves without an anomaly across the Néel temperature, T_{N}. Upon Rh doping, it collapses rather rapidly and vanishes around x=0.055. Notably, just as the Mott gap vanishes yet another gap appears that is of the Slater-type and develops right below T_{N}. This Slater gap is only partial and is accompanied by a reduced scattering rate of the remaining free carriers, similar as in the parent compounds of the iron arsenide superconductors.

Scaling of the Fano Effect of the In-Plane Fe-As Phonon and the Superconducting Critical Temperature in Ba_{1-x}K_{x}Fe_{2}As_{2}.

By means of infrared spectroscopy, we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba_{1-x}K_{x}Fe_{2}As_{2}. The Fano parameter 1/q^{2}, which is a measure of the phonon coupling to the electronic particle-hole continuum, shows a remarkable sensitivity to the magnetic and structural orderings at low temperatures. Most strikingly, at elevated temperatures in the paramagnetic tetragonal state we observe a linear correlation between 1/q^{2} and the superconducting critical temperature T_{c}. Based on theoretical calculations and symmetry considerations, we identify the relevant interband transitions that are coupled to the Fe-As mode. In particular, we show that a sizable xy orbital component at the Fermi level is fundamental for the Fano effect and, thus, possibly also for the superconducting pairing.

Temperature-Driven Topological Phase Transition and Intermediate Dirac Semimetal Phase in ZrTe_{5}.

We present an infrared spectroscopy study of ZrTe_{5}, which confirms a recent theoretical proposal that this material exhibits a temperature-driven topological quantum phase transition from a weak to a strong topological insulating state with an intermediate Dirac semimetal state around T_{p}≃138 K. Our study details the temperature evolution of the energy gap in the bulk electronic structure. We found that the energy gap closes around T_{p}, where the optical response exhibits characteristic signatures of a Dirac semimetal state, i.e., a linear frequency-dependent optical conductivity extrapolating to the origin (after subtracting a weak Drude response). This finding allows us to reconcile previous diverging reports about the topological nature of ZrTe_{5} in terms of a variation of T_{p} that depends on the crystal growth condition.

DIAPHRAGM KINETICS IN PULMONARY FIBROSIS PATIENTS AND GASTROESOPHAGEAL REFLUX.

72 patients with pulmonary fibrosis were examined with ultrasound method. Some of them have also gastroesophageal reflux. Changes in amplitude of diaphragm motion during intensified breathing were informative. Diaphragm level in patients with gastroesophageal reflux was lower than without refiux.

Disturbance in the allocation of carbohydrates to regenerative organs in transgenic Nicotiana tabacum L.

Transgenic tobacco (Nicotiana tabacum L, cv. SR-1) expressing mannitol 1-phosphate dehydrogenase, MTLD, in chloroplasts and myo-inositol O-methyltransferase, IMT1, in the cytosol after crossing of lines which expressed these foreign genes separately has been analysed. Plants expressing both enzymes accumulated mannitol and D-ononitol in amounts comparable to those following single gene transfer and showed phenotypically normal growth during the vegetative stage. Induction of flowering for transgenovar and wild-type occurred at the same time, but during flowering the phenotype of the transformed plants changed. Compared to wild-type, transgenic plants were characterized by curled, smaller upper leaves and elongated stems during flowering; incomplete development of flower buds with shorter sepals and pedicels resulted in increased abortion. Flowers completing development were normal. The vegetative biomass of the transformed plants was slightly higher than that of wild-type. Concentrations of soluble sugars and potassium were lower than in wild-type only in the apical parts of the transgenic plants. Both enzymes, under control of the CaMV 35S promoter, promoted accumulation of mannitol and D-ononitol in the youngest leaves close to the vegetative meristem and in flowers, suggesting that their presence could signal lower sink demand leading to a decrease in carbon import to flowers and developing seed capsules. The interpretation here is that increases of inert carbohydrates in developing sinks interfere with metabolism, such as respiration or glycolysis. This interference may be less significant in source tissues during vegetative growth than in sink tissues during seed development.

Plant stress adaptations--making metabolism move.

Persistently sub-optimal environmental conditions constitute stress. Perception and signaling lead to protein expression changes, the activation of new biochemical pathways, and repression of others which are characteristic of the unstressed state. Protective metabolic adaptations alter physiological reactions of the whole plant. Paramount among the mechanisms are oxygen radical scavenging, maintenance of ion uptake and water balance, and reactions altering carbon and nitrogen allocation, such that reducing power is defused. Elements of the stress signaling pathways and proteins that lead to stress protection have recently become known.

Increased Salt and Drought Tolerance by D-Ononitol Production in Transgenic Nicotiana tabacum L.

A cDNA encoding myo-inositol O-methyltransferase (IMT1) has been transferred into Nicotiana tabacum cultivar SR1. During drought and salt stress, transformants (I5A) accumulated the methylated inositol D-ononitol in amounts exceeding 35 [mu]mol g-1 fresh weight In I5A, photosynthetic CO2 fixation was inhibited less during salt stress and drought, and the plants recovered faster than wild type. One day after rewatering drought-stressed plants, I5A photosynthesis had recovered 75% versus 57% recovery with cultivar SR1 plants. After 2.5 weeks of 250 mM NaCl in hydroponic solution, I5A fixed 4.9 [plus or minus] 1.4 [mu]mol CO2 m-2 s-1, whereas SR1 fixed 2.5 [plus or minus] 0.6 [mu]mol CO2 m-2 s-1. myo-Inositol, the substrate for IMT1, increases in tobacco under stress. Preconditioning of I5A plants in 50 mM NaCl increased D-ononitol amounts and resulted in increased protection when the plants were stressed subsequently with 150 mM NaCl. Pro, Suc, Fru, and Glc showed substantial diurnal fluctuations in amounts, but D-ononitol did not. Plant transformation resulting in stress-inducible, stable solute accumulation appears to provide better protection under drought and salt-stress conditions than strategies using osmotic adjustment by metabolites that are constitutively present.

Regulation of Photosynthetic Induction State in High- and Low-Light-Grown Soybean and Alocasia macrorrhiza (L.) G. Don.

Alocasia (Alocasia macrorrhiza [L.] G. Don) and soybean (Glycine max [L.]) were grown under high or low photon flux density (PFD) conditions to achieve a range of photosynthetic capacities and light-adaptation modes. The CO2 assimilation rate and in vivo linear electron transport rate (Jf) were determined over a range of PFDs and under saturating 1-s-duration lightflecks applied at a range of frequencies. At the same mean PFD, the assimilation rate and the Jf were lower under the lightfleck regimes than under constant light. The activation state of two, key enzymes of the photosynthetic carbon reduction cycle pathway, ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and fructose-1,6-bisphosphatase, and the photosynthetic induction states (ISs) were also found to be lower under flashing as compared to continuous PFD. Under all conditions, the IS measured 120 s after an increase in PFD to constant and saturating values was highly correlated with the Rubisco activation state and stomatal conductances established in the light regime before the increase. Both the fructose-1,6-bisphosphatase and Rubisco activities established in a particular light regime were highly correlated with the mean Jf in that regime. The relationships between enzyme activation state and Jf and between IS and enzyme activation state were similar in soybean and Alocasia and were not affected either by growth-light regime, and hence photosynthetic capacity, or by flashing versus constant PFD. The common relationship between the linear Jf and the activation state of key enzymes suggests that electron transport may be the determinant of the signal regulating IS, at least to the extent that the IS is controlled by the activation state of key stromal enzymes.