Changes In KCl Concentration Research Articles

High-Resolution Graphene Films for Electrochemical Sensing via Inkjet Maskless Lithography.

Solution-phase printing of nanomaterial-based graphene inks are rapidly gaining interest for fabrication of flexible electronics. However, scalable manufacturing techniques for high-resolution printed graphene circuits are still lacking. Here, we report a patterning technique [i.e., inkjet maskless lithography (IML)] to form high-resolution, flexible, graphene films (line widths down to 20 μm) that significantly exceed the current inkjet printing resolution of graphene (line widths ∼60 μm). IML uses an inkjet printed polymer lacquer as a sacrificial pattern, viscous spin-coated graphene, and a subsequent graphene lift-off to pattern films without the need for prefabricated stencils, templates, or cleanroom technology (e.g., photolithography). Laser annealing is employed to increase conductivity on thermally sensitive, flexible substrates [polyethylene terephthalate (PET)]. Laser annealing and subsequent platinum nanoparticle deposition substantially increases the electroactive nature of graphene as illustrated by electrochemical hydrogen peroxide (H2O2) sensing [rapid response (5 s), broad linear sensing range (0.1-550 μm), high sensitivity (0.21 μM/μA), and low detection limit (0.21 μM)]. Moreover, high-resolution, complex graphene circuits [i.e., interdigitated electrodes (IDE) with varying finger width and spacing] were created with IML and characterized via potassium chloride (KCl) electrochemical impedance spectroscopy (EIS). Results indicated that sensitivity directly correlates to electrode feature size as the IDE with the smallest finger width and spacing (50 and 50 μm) displayed the largest response to changes in KCl concentration (∼21 kΩ). These results indicate that the developed IML patterning technique is well-suited for rapid, solution-phase graphene film prototyping on flexible substrates for numerous applications including electrochemical sensing.

Comparison of soil extraction parameters for Al, Mn, Ca, and Mg determinations

Abstract Inductively coupled argon plasma atomic emission spectroscopy (ICAP‐AES) is frequently used for analysis of soil extracts. Advantages include increased detection limits, simultaneous multi‐element capabilities, speed, and operator safety due to inert, non‐combustible source gas. Previous research showed that instrumentation problems increased with increasing salt content in soil extracting solutions. An ICAP‐AES was used to analyze AI, Mn, Ca, and Mg in KCl soil extracts under various KCl concentrations, soil: solution ratios, and shaking times for two acidic soils in Oklahoma. Changes in KCl concentration and soil: solution ratio resulted in differences in extractable Al, Mn, Ca, and Mg for both soils. Shaking time did not affect extractable Al in either soil, but did affect extractable Mn. Extractable Ca and Mg varied in one of the soils as a result of shaking time. The most effective extraction parameters selected based on these soils were 0.5M KCl, 10 min. shaking time, and 1: 15 soil: solution ratio.

マイナス温度域未凍結条件下におけるミオシンＢの変性に及ぼすＫＣｌ濃度と貯蔵温度の影響

In order to investigate the effect of KCl and temperature on the freeze denaturation of myosin B prepared from seven kinds of fish, myosin B-KCl solutions were stored under un-frozen conditions in a range of 0 ?? -8°C with various combinations of KCl concentrations and storage temperatures. The rate constant (kF) for inactivation of myosin B Ca-ATPase was affected by changes in KCl concentration rather than temperature in the range above the eutectic point of the KCl solution. The effect of KCl concentration differed markedly in each fish. When the change of the subunit composition in myosin B was compared in terms of changes in various ATPase activities, thermal inactivation mode of myosin B Ca-ATPase and content of soluble components in 0.1M KCl solution, it was found that the rates of denaturation of F-actin and of the enzymatic site of myosin molecule differed in each fish, i.e. carp, rainbow trout, and fat greenling.

An actin-depolymerizing protein (destrin) from porcine kidney. Its action on F-actin containing or lacking tropomyosin.

An Mr 19 000 protein (destrin) that has the ability to rapidly depolymerize F-actin in a stoichiometric manner was purified from porcine kidney by sequential chromatography on DNase I-agarose, hydroxyapatite, and Sephadex G-75. Its actin-depolymerizing activity is reversibly controlled by changes in KCl concentration but is insensitive to Ca2+ concentration. The rate of depolymerization of F-actin by destrin is much faster than that of spontaneous depolymerization induced by dilution and is not markedly decreased by the addition of end-blocking reagents such as cytochalasin B. These results suggest that destrin depolymerizes F-actin by interacting directly with F-actin protomers. Binding of muscle tropomyosin to F-actin slows down the rate of destrin-induced depolymerization of F-actin by about 30-fold. The data suggest that the destrin-induced depolymerization occurs from the ends of F-actin when F-actin is complexed with tropomyosin, but it takes place from the entire length of F-actin in the absence of tropomyosin.

Preparation and analysis of polyribosomes isolated from Tetrahymena pyriformis

1. 1. The Mg 2+ concentration of the solutions used for harvesting cells and preparing postmitochondrial supernatants must be above 4 mM to avoid polysome disaggregation. 2. 2. Sequential reduction of the concentration below this threshold value resulted in a progressive lowering of the polysome size with a concomitant increase in monomeric ribosomes or subunit levels. 3. 3. Changes in KCl concentration or pH value of the isolation buffers did not affect the polysomes. 4. 4. The cell harvesting method used will affect the profiles obtained. For consistent results, the cells must be rapidly chilled prior to harvesting. 5. 5. A variety of cell breakage methods were examined and it was found that some methods produced more reliable results than others. The poorer methods produced smaller classes of polysome suggesting that damage had been sustained by the protein synthetic machinery during isolation. 6. 6. Extracts from different strains of Tetrahymena were examined and the polysome profiles obtained correlated with the cell doubling time. Similar experiments were performed with strain HSM, where the effects of growth medium composition on polysome profiles and on cell doubling times were compared.

Properties of the conductance induced in lecithin bilayer membranes by alamethicin.

Current-voltage relations have been measured across lecithin bilayers doped with alamethicin molecules. The results show that there are two aspects of the induced conductances, a voltage-dependent and a voltage-independent conductance. Both have been characterized as a function of alamethicin and KCl concentration. The two aspects of the conductances do not show the same changes with those two variables. The voltage-independent conductance is affected very little by changes in KCl concentration, and its dependance on alamethicin concentration reveals that it is produced by two or three alamethicin molecules. The voltage-dependent conductance is shifted by the changes in KCl concentration only when the concentrations are greater than or equal to 100 mM; below 100 mM KCl the slope of the log conductance-voltage curve is also reduced. The effect of changing alamethicin concentration reveals that nine or ten molecules are involved for KCl concentrations larger than 100 mM; if the KCl concentration is less than 100 mM, the effect of changing the alamethicin concentration is reduced. Time-dependent measurements have also been performed; only one time constant was found and it is strongly voltage-dependent. Also a very slow voltage-dependent absorption process is found. These results can be explained if it is assumed that pores are formed of a mixture of charged and uncharged alamethicin molecules when a voltage is applied and that uncharged alamethicin can also form pores without applying a voltage, once the absorption process has been started by previously applied voltages. The voltage dependence of the time constant seems to indicate that the voltage-dependent pore formation is produced by aggregates of charged alamethicin rather than independent molecules.

Presence of Two Different Membrane-bound, KCl-stimulated Adenosine Triphosphatase Activities in Maize Roots

Recent publications have indicated that a KCl-stimulated ATPase from cereal roots is specifically associated with plasmalemma-enriched membrane fractions. However, in previous work we found that relatively high specific activities of this enzyme were also associated with a membrane fraction which did not contain plasmalemma. In an attempt to clarify this discrepancy, we have investigated the effect of density gradient composition upon the association of the enzyme with different membrane fractions isolated from the roots of Zea mays L. (WF9 x M14).When roots were fractionated on a single, discontinuous sucrose density gradient the KCl-stimulated ATPase activity was concentrated in membrane fractions of relatively high density (sigma = 1.17-1.22) which were enriched in plasmalemma. When fractions were isolated on both Ficoll and sucrose density gradients, KCl-stimulated ATPase activity was again found associated with plasmalemma and also in a second membrane fraction which did not contain plasmalemma. This fraction was found at relatively low densities (sigma = 1.08) on the Ficoll gradient. The precise identity of the membrane in this fraction could not be determined.A preliminary investigation into the properties of the two KCl-stimulated ATPase activities indicated that both had acid pH maxima and both displayed similar responses to changes in KCl concentration.