Remarks on preparation of indandione detection reagents

A modified Claisen condensation with sliced sodium at a higher temperature was recommended for the production of ungranulated charcoal. A new ninhydrin production method by oxidation of benzaldiketohydrinden using available reagents was tried and was unsuccessful. Triketohydrinden was obtained by boiling ninhydrin in acetic acid anhydrides

Electronic properties of very thin native SiO2/a-Si:H interfaces and their comparison with those prepared by both dielectric barrier discharge oxidation at atmospheric pressure and by chemical oxidation

The contribution deals with electronic properties of thin oxide/amorphous hydrogenated silicon (a-Si:H) measured by capacitance-voltage (C-V) and charge version of deep level transient spectroscopy (Q-DLTS). The interest was focused on the studies of the interface properties of very thin dielectrics formed by dielectric barrier discharge (DBD) or natively on the a-Si:H layer. These properties were compared with those of oxide layers prepared by chemical oxidation in HNO3. The DBD was used for the preparation of a very thin SiO2 layer on a-Si:H for the first time to our knowledge. Preliminary electrical measurements confirmed that a very low interface states density was detected in the case of the native oxide/a-Si:H and DBD oxide/a-Si:H

Steady state evaluation of distributed secondary frequency control strategies for microgrids in the presence of clock drifts

Secondary frequency control, i.e., the task of restoring the network frequency to its nominal value following a disturbance, is an important control objective in microgrids. In the present paper, we compare distributed secondary control strategies with regard to their behaviour under the explicit consideration of clock drifts. In particular we show that, if not considered in the tuning procedure, the presence of clock drifts may impair an accurate frequency restoration and power sharing. As a consequence, we derive tuning criteria such that zero steady state frequency deviation and power sharing is achieved even in the presence of clock drifts. Furthermore, the effects of clock drifts of the individual inverters on the different control strategies are discussed analytically and in a numerical case study

Modelling, Analysis and Experimental Validation of Clock Drift Effects in Low-Inertia Power Systems

Clock drift in digital controllers is of great relevance in many applications. Since almost all real clocks exhibit drifts, this applies in particular to networks composed of several individual units, each of which being operated with its individual clock. In the present paper, we demonstrate via extensive experiments on a microgrid in the megawatt range that clock drifts may impair frequency synchronization in low-inertia power systems. The experiments also show that-in the absence of a common clock-the standard model of an inverter as an ideal voltage source does not capture this phenomenon. As a consequence, we derive a suitably modified model of an inverter-interfaced unit that incorporates the phenomenon of clock drifts. By using the derived model, we investigate the effects of clock drifts on the performance of droop-controlled grid-forming inverters with regard to frequency synchronization and active power sharing. The modeling and analysis is validated via extensive experiments on a microgrid in the megawatt range

The Increase of Epidermal Imidazoleacrylic Acid Following Insolation

It has been confirmed, by electron microscopy, that suction blisters detach the epidermis at the dermo-epidermal junction. Inter- and intracellular vacuolization was observed in some of the specimens. On the basis of a study comprising 15 subjects (12 males and 3 females), it was concluded that urocanic acid in the epidermis (suction blister skin) of the upper arm increased 9–11 days following insolation in comparison with specimens situated at an exactly symmetrical site of the control (non-irradiated) arm. This difference was significant in terms of μg urocanic acid per mg dry weight at a 95% level of probability and in terms of μg per cm2 of blister base at a 99% level (t-test for paired values). In two of the subjects other time intervals after insolation were also studied and an increase of epidermal urocanic acid level was noted. Dry weights of epidermis (mg per cm2) on the irradiated and control side (9–11 days following insolation) did not differ significantly in the group of 15 subjects. Significant increase due to insolation was only demonstrated when the values were divided by control values obtained for the respective arms 2 months before the experiment. Histidine ammonia-lyase activity was estimated in 8 subjects. The increase on the irradiated side on the 9–11th day after unilateral insolation was not significant

ForestGEO Dead Wood Census Protocol

After stems die, the wood persists in the ecosystem, either as standing deadwood or woody debris on the ground. Deadwood plays an important role in forest ecosystems, providing significantly different substrate, nutrient source, and microclimate to seedlings as well as habitat to vertebrates and invertebrates. Measurements of dead material on the forest floor can be used to more completely estimate biomass, carbon pools, and carbon fluxes. These methods continue the philosophy of the ForestGEO demography data by tracking the status of individual woody stems after mortality and thereby extending observations to the entire period each woody stem exists in the forest