Ba Solution Research Articles

Bioinspired Diffuse Reflectance Coatings for Fabric-Based Radiative Coolers

As global temperatures rise due to anthropogenic climate change, thermal comfort becomes an increasingly critical area of research. While most buildings are equipped to cool and heat their interiors, this process is very energy intensive; a smarter approach is to enable personal thermal management using clothing and textiles. In particular, we are interested in the ability to use textiles and clothing to cool bodies in extreme heat, both to maintain comfort and prevent deaths in urban deserts due to heat stroke. One innovative category in this realm is radiative coolers—surfaces adept at manipulating light to passively regulate temperature. These coolers achieve sub-ambient surface temperatures by selectively reflecting or refracting sunlight wavelengths (200nm-2.5µm) while emitting infrared light (8-13µm). This unique capability allows them to maintain cooler temperatures, even when exposed to direct sunlight and the open sky. Coatings facilitating this cooling action typically consist of a porous media filled with refractive gaps, requiring specific substrates and custom production processes, thereby limiting their applications. Furthermore, the necessity of low light transmission presents issues in creating fabrics that radiatively cool while still retaining high breathability and durability. In this study we present a method whereby an optically active coating comprised of a mixture of CaCO3 and BaSO4 microcrystals was applied to multiple fabric substrates to create a radiative cooler. Through the use of photoinitiated chemical vapor deposition (pICVD), a 5 µm thick layer of a hydrophilic polymer polyhydroxyethyleneacrylate (pHEA) was deposited on the fabric substrate. Subsequently, through serial immersion in solutions containing Ca and Ba ions and solutions containing CO3 and SO4 ions, inorganic microcrystals were grown directly on the surface of the fabric. These microcrystals formed with a large polydispersity, endowing the coating with excellent reflective properties in the solar spectrum. Mie scattering calculations confirmed that the CaCO3 and BaSO4 microcrystals were primarily responsible for scattering. Further simulations using finite difference time domain software revealed, surprisingly, that surface-immobilized crystals provided the highest reflection efficiency, indicating that composite fibers with embedded particles are not as efficient. Upon outdoor testing, the device showed a cooling ability of 8°C compared to an uncoated fabric, achieving a maximum cooling of 4°C below ambient temperature. Washing and durability testing of the coating found no degradation in the material's performance, affirming its resilience and long-term effectiveness.

Respons Pertumbuhan Planlets Anggrek Phalaenopsis terhadap Pemberian BA dan NAA Selama Aklimatisasi

Orchid plants are a type of plant that belongs to the Orchidaceae family which has approximately 900 genera and estimated to have 15.000- 25.000 species. Orchid plants can be cultivated vegetative and generative. Tissue culture is one of the vegetative propagation methods of orchids. Acclimatization is a critical period for tissue cultured plantlets. Acclimatization is a critical period for plantlets resulting from tissue culture. Plant growth regulators can help stimulate plantlet growth during the acclimatization period. growth regulators is one of the success factors in acclimatization. This study aims to determine the best BA and NAA concentrations and the best treatment combination for acclimatization of Phalaenopsis orchids. This research was conducted from March to July 2022 at the Research and Experimental station, University of Bangka Belitung. This study used a factorial randomized block design (RBD). The factors tested were the concentrations of BA and NAA solutions. The results showed that the acclimatization of Phalaenopsis orchids was successful, indicated by the high percentage of plantlet survival. The highest average growth was shown at concentrations of 10 ppm BA and 10 ppm NAA. The treatment combination showing the highest average growth was BA 20 + NAA 10 ppm.Keywords : Acclimatization, BA, NAA, Phalaenopsis

First-Order Derivative Spectrophotometry Method with Triapine as Chelating Agent for Simultaneous Determination of Barium(II) and Lead(II)

A simple, selective and sensitive first-order spectrophotometric method was used for the simultaneous determination of Ba(II) and Pb(II) with triapine as chelating agent. When triapine reagent was mixed with Ba(II) and Pb(II) solutions, it produces a light green colour in a basic medium. Maximum peaks for both Ba(II) and Pb(II) were observed at pH 8.5 (basic buffer solution) between 350 and 395 nm. Ba(II)-triapine has a molar absorbance of 5.276 × 106 L mol-1 cm-1 and a Sandell’s sensitivity of 0.000189 g/cm2. Similarly, they are 9.421 × 105 L mol-1 cm-1 and 0.00106 g/cm2 for Pb(II)-triapine, respectively. The stability constants of Ba(II)-triapine and Pb(II)-trapine complexes are 3.207 × 104 and 5.118 × 104, respectively. The effects of Ba(II)-triapine and Pb(II)-triapine concentrations on amplitude were also studied. The detection and quantification limits for Ba(II)-triapine are 0.0882 g/mL and 0.746 g/mL, respectively. Similarly, detection and quantification values were 0.089 g/mL and 0.745 g/mL for Pb(II)-triapine, respectively. The developed or proposed method was used to examine biological samples of carrots, onions, beans, paints, milk powder and alloys. The sample results were close to the certified reference values for the ICP-AES, FDA and AAS methods.

Optimization and Characterization of Low-Molecular-Weight Chitosan-Coated Baicalin mPEG-PLGA Nanoparticles for the Treatment of Cataract.

The present study was to evaluate the potential effectiveness of low-molecular-weight chitosan-coated baicalin methoxy poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) (mPEG-PLGA) nanoparticles (BA LCH NPs) for the treatment of cataract. mPEG-PLGA NPs were optimized by the Box-Behnken design and the central composite design based on the encapsulation efficiency and drug loading. Then, the BA LCH NPs were characterized based on morphology, particle size, and zeta potentials. The analytical data of differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy depicted the drug excipient compatibility. In vitro, we evaluated cell viability, cellular uptake, potential ocular irritation, transcorneal permeability, and the precorneal retention of BA LCH NPs. In vivo, the chronic selenium cataract model was selected to assess the therapeutic effect of BA LCH NPs. The size of BA LCH NPs was within the range from 148 to 219 nm and the zeta potential was 19-25 mV. Cellular uptake results showed that the fluorescence intensity of the preparations in each group increased with time, and the fluorescence intensity of the LCH NP group was significantly higher than that of the solution group. The optimized BA LCH NPs improved precorneal residence time without causing eye irritation and also showed a sustained release of BA through the cornea for effective management of cataract. Also, fluorescence tracking on the rabbit cornea showed increased corneal retention of the LCH NPs. In addition, the results of therapeutic efficacy demonstrated that BA LCH NPs can significantly reduce the content of malondialdehyde and enhanced the activities of catalase, superoxide dismutase, and glutathione peroxidase, which was comparable to positive control and better than the BA solution group. Thus, it can be inferred that the BA LCH NPs are a promising drug delivery system for enhancing the ophthalmic administration of BA to the posterior segment of the eye and improving cataract symptoms.

A New Saddle-Shaped Aza Analog of Tetraphenylene: Atroposelective Synthesis and Application as a Chiral Acylating Reagent

A New Saddle-Shaped Aza Analog of Tetraphenylene: Atroposelective Synthesis and Application as a Chiral Acylating Reagent

PGR and Its Application Method Affect Number and Length of Runners Produced in ‘Maehyang’ and ‘Sulhyang’ Strawberries

Vegetative propagation using runner plants is an important method to expand the cultivation area for the strawberry (Fragaria × ananassa Duch.). However, excessively long runners need an increased total amount of nutrients and energy to receive elongation from mother plants, which may lead to poor growth or reduced output. The use of plant growth regulators (PGRs) is an adoptable way to solve such problems. The objectives of this experiment were to study the effects of PGRs and their application methods on the growth and development of runners, runner plants, and mother plants, and also to find effective ways to control the number and length of runners without harmful side effects. Chlormequat chloride (CCC), 6-benzylaminopurine (BA), and ethephon (ETH) at a concentration of 100 mg·L−1 were applied via three different methods: injection into crowns, medium drench, and foliar spray. The results showed that BA injection into crowns was the most effective combination among all treatments, which prominently shortened the length of runners and increased the number of runners and leaves on a single plant. Furthermore, plants with BA solution injection tended to produce stronger runners with higher fresh and dry weights, without affecting the health states of mother plants. The ETH solution seemed to have toxic effects on plants, by leading many dead leaves and weak runners, and increased activities of antioxidant enzymes. Other than the injection method, the other two application methods of the CCC solution did not significantly affect the growth and development of both cultivars. Runner plants grown for 30 days were not affected by any treatments, and they were in similar conditions. Overall, BA injection into crowns is recommended for controlling the number and length of strawberry runners.

High Concentration of Benzyladenine Solution Stimulates Anthers for Inducing Callus in Ricinus Communis L.

An high-frequency protocol for induction of callus from anther explants of Ricinus communis was described. When anther explants of R. communis was cultured directly onto medium containing 6-benzylaminopurine (BA) induced formation of only poor quality callus that had a low induction frequency of anther callus (10.67%). However, treating the anther explants with high concentrations (7.5-120 mg/L) of BA solution for short time periods (5-80 min) helped to improve the induction frequency and enhance the quality of the callus formation significantly. The best callus induction (41.25%) was observed when anther explants were treated with 15 mg/L BA solution for 10 min before being inoculated onto hormone-free Murashige and Skoog (MS) medium for 30 days. In order to further optimize the culture system, after treated with 15 mg/L BA for 10 min, anther explants were inoculated on the hormone-free MS medium contained concentrations of sodium nitroprusside (SNP). The results showed that SNP significantly promoted the response of callus induction, especially when 8 mg/L SNP was applied, the the highest percentage of callus induction (60.37%) were gained.

Tannin-boron complex as a preservative for 3-ply beech plywoods designed for humid conditions

Abstract Boric acid (BA) effectively controls wood-rotting fungi and termite attack but is readily leached out in outdoor exposure. A newly developed tannin-boron (TB) complex has been investigated to reduce BA leaching and to preserve beech plywood from biological attack. Wood veneers were impregnated with different TB solutions and then bonded with a melamine urea formaldehyde (MUF) adhesive for bond class 2 applications. The formation of a solid hydrophobic TB network on the veneer surfaces partially decreased the tensile shear strength of plywood but the prepared panels met the requirements for bond class 2. The plywood samples made from veneers treated with only BA solutions showed fair resistance against white rot fungus and termite attack, but the durability decreased even after mild leaching tests. The panels made of treated veneers with TB formulations showed instead a high resistance against biological attack after mild leaching and to some extent after severe leaching tests. This depended on the concentration of tannin and BA in the solutions. Favorable results were obtained with 20% tannin in the formulation. The results of the termites feeding choice test were more positive than those obtained by a forced feeding test. The control samples were attacked faster and showed higher weight loss when alternative samples included TB formulations.

Crystal structures and thermal expansion of Sr1–x Ba x Bi2B2O7 solid solutions

A series of Sr1–xBaxBi2B2O7 solid solutions (x = 0–1) have been synthesized by crystallization from glass ceramics. The crystal structures of solid solutions at x = 0.65 and x = 1 were solved by direct methods of X-ray diffraction from single crystal data and refined in a reduced cell (\({a_{Ba}}{\kern 1pt} = {a_{Sr}}/\sqrt 3 \)) relative to SrBi2B2O7 in the same space group P63. Using the Rietveld method, the phase transition range at x = 0.65–0.70 with a reduction of the unit cell has been revealed. As was shown by method of high-temperature powder X-ray diffraction, the solid solutions demonstrated an anisotropic thermal expansion (TE) upon heating in air.

Nanostructural evolution of one-dimensional BaTiO₃ structures by hydrothermal conversion of vertically aligned TiO₂ nanotubes.

The use of TiO2 nanotube (NT) arrays as templates for hydrothermal conversion of one-dimensional barium titanate (BaTiO3) structures is considered a promising synthesis approach, even though the formation mechanisms are not yet fully understood. Herein we report a nanostructural study by means of XRD and (HR)TEM of high aspect ratio TiO2-NTs hydrothermally converted into BaTiO3. The nanostructure shows two different and well-defined regions: at the top the conversion involves complete dissolution of NTs and subsequent precipitation of BaTiO3 crystals by homogeneous nucleation, followed by the growth of dendritic structures by aggregation and oriented attachment mechanisms. Instead, at the bottom, the low liquid/solid ratio, due to the limited amount of Ba solution that infiltrates the NTs, leads to the rapid crystallization of such a solution into BaTiO3, thus allowing the NTs to act as a template for the formation of highly oriented one-dimensional nanostructures. The in-depth analysis of the structural transformations that take place during the formation of the rod-like arrays of BaTiO3 could help elucidate the conversion mechanism, thus paving the way for the optimization of the synthesis process in view of new applications in energy harvesting devices, where easy and low temperature processing, controlled composition, morphology and functional properties are required.

Potential side effects of biocontrol and plant-growth promoting Bacillus amyloliquefaciens bacteria on earthworms

Many bacteria strains are now successfully used for plant-growth promotion (PGPR) and as biocontrol agents (BCA) against plant diseases. Mechanisms behind their action involve production of enzymes and antibiotics, which in high concentrations could also affect non-target organisms hence the biodiversity and processes in the soil. Despite these potential negative side effects, there is little research done on the subject to confirm whether they are significant. In three laboratory experiments, we tested the effect of the bacterial BCA Bacillus amyloliquefaciens UCMB5113 (BA) on two earthworm species, common in agricultural soils in temperate regions of the world and representing different ecological groups; one anecic (Aporrectodea longa) and one endogeic species (Aporrectodea caliginosa). The earthworms were kept in replicated pots containing soil from local agricultural fields. They were fed on cow manure, and exposed to BA by (1) dipping into a BA solution (short-term external exposure in high concentration), (2) mixing BA solution into the soil (long term external and internal exposure) and (3) feeding earthworms with BA infested plant litter (internal exposure of the gut).After 1–2 months, survival, growth and reproduction of the earthworms were recorded. We found no effect of the treatments as compared to control without BA amendments. We conclude that the use of high doses of BA with concentrations at the same magnitude as maximally expected when the bacteria are used as PGPR and BCA, is not harmful to the soil dwelling earthworms tested in this project. Further studies of the ecological effects of PGPR and BCA bacteria on other non-target soil organisms are encouraged. The development of sustainable agricultural systems, where ecosystem services are optimized, has to be aided by a deeper knowledge of the combined effect of bacteria and earthworms on the promotion of plant health.

Catalytic Activity of Double-Perovskite Type BalnMn2O5 for Oxygen Reduction Reaction Using in Rechargeable Zinc-Air Batteries

There have been increased demands for the development of high energy efficient and affordable energy storage devices as the alternatives to lithium-ion secondary batteries for electrical vehicles, portable electronic devices and so on. Recently, rechargeable zinc-air batteries have attracted much attention from the point of view of high-capacity and safety batteries. To realize the rechargeable zinc-air batteries, active cathode catalysts for oxygen reduction reaction and evolution reaction (ORR and OER) play important roles in the overall battery performance because of the majority of energy losses occurring at the cathode reactions. It is well known that the transition-metal oxide family with a perovskite-type ABO3 structure is one of the promising catalysts for ORR and OER. Especially, manganese oxides such as LaMnO3+δ and La1-xCaxMnO3 showed high ORR activities. Some researchers reported that the ORR activity for oxide catalysts primarily correlates to the electronic states and valence of Mn. However, a clear strategy has not been revealed to prepare active catalysts for ORR. On the other hand, more recently, in the case of high-temperature oxygen intake/release reactions of the double-perovskite type BaLnMn2O5+δ (Ln = Y, Gd, Nd and La; Fig. 1a), Motohashi et al. reported that the redox characteristics could be controlled by the radius of Ln ions, even though the valence of Mn remained unchanged [1]. Therefore, in this study, we focused on the ORR activity of the double-perovskite type BaLnMn2O5+δ (Ln: Y, Gd, Nd and La). BaLnMn2O5+δ (Ln: Y, Gd, Nd, and La) powder catalysts were synthesized via a citrate precursor route combined with the oxygen-pressure-controlled encapsulation technique. Ln 2O3 (fired at 1000°C overnight prior to use), Ba(NO3)2 and Mn(NO3)2·6H2O were used as starting materials. Appropriate amounts of these reagents were dissolved in diluted HNO3 (for Ln 2O3) or Milli-Q water [for Ba(NO3)2 and Mn(NO3)2·6H2O] to prepare Ln, Ba, and Mn nitrate solutions. These solutions were mixed in a crucible in which equimolar citric acid was subsequently added as a complexing agent. The citrate solution was stirred and heated at 60-70°C to promote polymerization. The gelatinous product was prefired at 450°C in air for 1 h and then at 1000°C in flowing N2 gas for 24 h. The resulting precursor powder was pressed into pellets and placed in an evacuated silica ampule together with an equal amount of FeO powder, which acts as a getter for excess oxygen. The silica ampule was heated at 1100°C for 24 h, followed by quenching into ice water. The crystallinity, morphology and particle size of the resultant samples were characterized with XRD and SEM. Electrochemical measurements were carried out using a rotating ring disk electrode (RRDE, Pt ring) with a conventional three electrode system. The catalyst ethanol ink (BaLnMn2O5: acetylene black: Nafion = 5: 1: 1) was dropped and dried on a glassy carbon electrode as a working electrode. A Pt plate and a Hg/HgO electrode were used as a counter electrode and a reference electrode, respectively. Argon- or oxygen-saturated 4 mol dm-3 potassium hydroxide aqueous solution was used as an electrolyte. The scan speed and rotating speed of the RRDE were 1 mV sec-1 and 1600 rpm, respectively. The XRD data indicate that all the as-synthesized BaLnMn2O5+δ products are essentially phase-pure of the fully reduced δ ≈ 0 form with a tetragonal unit cell. Both the a- and c-axis lengths are in agreement with those in the previous literature. As expected, these values systematically increase with the increasing ionic radius of Ln 3+ in the order of Y, Gd, Nd, and La. The oxygen content (5+δ) values determined by iodometry are close to 5.00 for all the Ln-products. The particle sizes of the samples were almost the same as 1~2 μm. Fig 1b shows onset potentials for ORR as a function of the radius of Ln ions of the samples. It can be seen that the onset potential is shifted toward positive side as the radius of the Ln ions increases, in spite of the fixed Mn valence for all the samples. The most active catalysts for ORR were BaNdMn2O5 and BaLaMn2O5, which contain larger Ln ions. The result implied that the size of A site ion played an important role in the catalytic activity for ORR.Fig. 1 (a) the crystal structure and (b) the onset potentials for ORR as a function of the radius of Ln ions of BaLnMn2O5+δ (Ln: Y, Gd, Nd, and La).[1] T. Motohashi, M. Kimura, T. Inayoshi, T. Ueda, Y. Masubuchi and S. Kikkawa, Dalton Trans. in press. Figure 1

Thermally modified molybdenum oxide as a potential sorbent for the removal of metal cations from aqueous solutions

The effectiveness of a low cost sorbent produced by thermal modification of ammonium heptamolybdate (AHM) in adsorption of radionuclides and heavy metals was investigated. The product was characterized by XRD, SEM and Raman spectroscopy. Sorption experiments were performed in Pb, U, Cs, Ba and Eu solutions (pH 2.0–6.0). The obtained isotherms were simulated by Langmuir and Freundlich isotherms and kinetics data were used in order to evaluate the sorption mechanism. The results showed the high and selective efficiency of the AHM-derived MoO3 especially in Pb and U removal whereas the desorption experiments revealed its environmental applicability under real conditions for the investigated metal cations.

Enhanced permeability across Caco-2 cell monolayers by specific mannosylating ligand of buserelin acetate proliposomes

Context: Oral delivery of peptide and protein drugs still remains the area of challenges due to their low stability and permeability across GI tract. Among numerous attempts, the receptor-mediated drug targeting is a promising approach to enhance GI permeability.Objective: The aim of this study was to prepare mannosylated buserelin acetate (MANS-BA) proliposome powders grafted with N-octadecyl-d-mannopyranosylamine (SAMAN) as targeting moiety and evaluate their permeability across Caco-2 cell monolayers.Materials and methods: The MANS-BA proliposome powders were prepared by coprecipitation method. The targeting moiety SAMAN was synthesized in-house and confirmed by characterization using Fourier transform infrared (FTIR) and differential scanning calorimeter (DSC).Results: The MANS-BA liposomes reconstituted from proliposome powders exhibited the oligolamellar vesicular structure of phospholipid bilayer. Their size, zeta potential and entrapment efficiency were in the ranges of 93.11–218.95 nm, −24.03 to −37.15 mV and 21.12–33.80%, respectively. The permeability of reconstituted MANS-BA liposomes across Caco-2 cell monolayers was significantly enhanced to about 1.2- and 2.2-fold over those of conventional BA liposomes and solution, respectively.Discussion: Increase in dicetylphosphate, cholesterol and SAMAN contents resulted in significant increase in size and zeta potential of reconstituted MAN-BA liposomes. The entrapment efficiency was increased with increasing dicetylphosphate and mannitol contents in liposomes containing cholesterol.Conclusions: The significantly enhanced permeability across Caco-2 cell monolayers of MANS-BA liposomes might be due to the role of mannose receptor on intestinal enterocytes.

The effects of treating persimmon (Diospyros lotus) seeds with moist-chilling and growth regulators on seeds germination, the subsequent seedling characters and their induced drought tolerance

The present experiment aimed at investigating the effects of seed pre-treatment with moist-chilling (mch), GA3, BA or their combinations on seed germination and subsequent drought resistance of the resulting seedlings. The obtained results indicated that increasing the moist-chilling period from 4 to 8 weeks progressively significantly increased the seeds germination percentages (average from 51.2% to 97.2%) and significantly decreased the time to 50% germination (T50) (average from 47days to 27.3 days). The control one (non-moist- chilled seeds) gave the lowest germination percentage (22.6%) and required the highest T50 (72.6 days). The 4 weeks-chilled seeds soaked in BA gave the most satisfactory results as it yielded high germination percentage (average 85.2%), low T50 (average 31.2 days) and saved about at least 4 weeks which would have otherwise being required for moist-chilling of the seeds. The best vegetative characteristics of 2.5-month-old persimmon seedlings were obtained from seeds treated with 8week-moist-chilling solely or with 4week- moist chilling followed by soaking in 20 ppm BA solution for 16 hr. After exposure the subsequent seedlings to 24 days drought period, the results revealed that increasing the moist-chilling period decreased proline content of the seedlings leaves and roots, while increased their leaf resistance to water vapour (LRWV) (9.9, 11.45 & 19.65 sec/cm for 0, 4, 8 weeks of mch, respectively). Generally, seeds pretreated with BA solely gave seedlings with significantly higher root proline content than those of the other treatments, and hence showing more drought resistance features. After the 24 days of drought, leaves of the seedlings resulting from either 4 or 8-weeks-chilled seeds had significantly higher values of chlorophyll (chl a, b) and total soluble carbohydrates (TSC) than those of their corresponding ones resulting from non-chilled seeds. In view of the above findings, the best combination that gave the most satisfactory results was soaking in BA of the seeds which were mois-chilled for 4 weeks.

CHF experiments using a 2-D curved test section with additives for IVR-ERVC strategy

► We conducted CHF experiments using a 2-D curved test section with TSP and BA. ► The CHF of TSP, and TSP + BA increased compared to that of DI water. ► The CHF enhancement could be explained by decreased contact angle. ► The CHF enhancement ratio decreased with increasing mass flux. This study describes critical heat flux (CHF) experiments using a 2-D curved test section with trisodium phosphate (TSP: Na 3 PO 4 ) and boric acid (BA: H 3 BO 5 ). The CHF values of TSP solution, BA solution, and TSP + BA solution were enhanced by as much as 50% for all experimental conditions except the condition of 150 mm radius with BA solution. The enhancement can be explained by decreased contact angle (enhancement of wettability). This CHF enhancement could provide additional thermal margin for the IVR-ERVC strategy.

Inelastic neutron scattering study of lead-free relaxor ferroelectric (Na0.5Bi0.5)0.96Ba0.04TiO3 single crystal

Low frequency phonons and diffuse scattering have been investigated in a single crystal of (Na0.5Bi0.5)1−x Ba x TiO3 solid solution with composition (x = 4%) close to the morphotropic phase boundary by means of inelastic neutron scattering. Constant-energy scans for momentum transfer Q = (2, 2, q) reveal a typical waterfall-type dispersion at room temperature. The anomalous steep dispersion occurs at q wf ≈ 0.15 r.l.u., similar to lead-based relaxors. Since these measurements are done well below the temperature interval of the relaxor-like dielectric dispersion, our findings support a generic, anharmonic phonon-coupling nature of the phenomenon.

Primary activity measurements with a 4πβ–4πγ coincidence counting system

The radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba solutions have been standardised using a 4πβ-4πγ coincidence counting system we have recently set up. The detection in the beta channel is performed using various geometries of a UPS-89 plastic scintillator optically coupled to a selected low-noise 1in. diameter photomultiplier tube. The light-tight thin capsule that encloses this beta detector is housed within the well of a 5in.×5in. NaI(Tl) monocrystal detector. The beta detection efficiency can be varied either by optical filtering or electronic discrimination when the electrons loose all their energy in the plastic scintillator. This 4πβ-4πγ coincidence system improves on our 4πβ(PC)-γ system in that its sample preparation is less labour intensive, it yields larger beta- and gamma-counting efficiencies thus enabling the standardisation of low activity sources with good statistics in reasonable time, and it makes standardising short-lived radionuclides easier. The resulting radioactive concentrations of (166m)Ho, (134)Cs and (133)Ba are found to agree with those measured with other primary measurement methods thus validating our 4πβ-4πγ coincidence counting system.

Solutional features and cave deposits related to hypogene speleogenetic processes in a littoral cave of Mallorca Island (western Mediterranean)

The Cova des Pas de Vallgornera, located in the southern part of Mallorca Island (western Mediterranean) and developed in Upper Miocene reefal carbonate limestones, is an exceptional coastal cave because of its particular morphological features and the presence of deposits with uncommon mineralogies. Littoral mixing dissolution processes represent the most important speleogenetic mechanism to be considered in the eogenetic karst platform, where it develops; nevertheless, part of the cave consists of an extensive network of galleries that show morpho-sedimentary features pointing up to a possible participation of hypogene speleogenesis. The morphological assemblage of the cave illustrates besides the typical coastal karstification, a noticeable meteoric water recharge along with a possible deep recharge of hypogenic character. Features consisting in upwards solutional channels are abundant, including a complete morphologic suite of rising flow supporting the involvement of hypogene speleogenetic processes. Furthermore, the presence of vents and some related speleothems, such as crusts and cave rims, together with Mn and Fe-rich deposits hosting several minerals not observed until present in other caves of the region must be highlighted. Given the monotonous surface geology around the cave, it is suspected that ascending Sr, Ba, Mn, and Al-rich hypogene solutions may have reacted with the host rock to form this unique mineral assemblage. These deep-seated speleogenetic and mineralogical phenomena could be associated with the feeble geothermal anomalies existing currently in the Llucmajor platform, related to SW–NE faults which delimitate the subsidence basin existing in the southern end of Mallorca Island.

The Effect of Indole-3-Acetic Acid and Benzyladenine on Sequential Leaf Senescence on Helianthus Annuus L. Seedlings

ABSTRACTThe effect of IAA and BA on the mechanism of senescence which occurs in the cotyledons of Helianthus annuus L. seedlings showing epigenic germination has been investigated. In this study 0,01μM and 10μM IAA solutions were sprayed to the leaves and BA solutions with the same concentrations—to the cotyledons of 16 days-old seedlings. We have determined chlorophyll content, protein amount, peroxidase activity and the changes in the membrane permeability in the cotyledons of the treated and control seedlings. Compared to the control cotyledons IAA in the concentrations of 10μM and 0,01μM caused a breakdown of chlorophyll at the ratio of 64% and 54%, respectively. Soluble protein levels in the IAA at 10μM treatment decreased in the ratio of 12%. IAA treatments with 10μM and 0,01μM stimulated POD activity with about 11 and 8 times, respectively. On the other hand, it has been observated that 10μM and 0,01μM BA treatment retarted senescence, whereas 0,01μM BA and 0,01 μM IAA when were applied together enhanced senescence. It has been discussed that IAA which is known as an allosteric activators of cytokinin oxidase stimulates the cytokinin oxidations so it increases senescence that occurs in the cotyledons. In this research, according to the results it has been thought that the senescence signal may be a substance in the nature of IAA.