Fruit size, mineral composition and quality of trickle-irrigated tomatoes as affected by potassium rates

An experiment was conducted to determine the fruit size, mineral composition and quality of trickle-irrigated tomatoes as affected by potassium fertilizer rates. Six potassium (K) rates were applied as KCl, corresponding to 0, 48.4, 118.6, 188.8, 259.0 and 399.4 kg ha-1, with four replicates, following a randomized block design. Quadratic responses to K rates were observed for double extra large (diameter > 60 mm), extra large (56 to 60 mm) and large (52 to 56 mm) fruit yields. Maximum yields of these classes were achieved with K rates of 116, 190 and 233 kg ha-1, respectively. Fruit dry matter, phosphorus, sulfur and magnesium contents were not affected by K rates, but nitrate and K contents showed significant increments as K rates were increased. Vitamin C, total soluble solids, lycopene and beta-carotene contents in the fruits were not affected by K rates. Increments in the K rate lowered the fruit pH and increased total acids content.

Control of Concrete Deterioration Due to Trace Compounds in Deicers, HR-299 Phase I, 1988

This report presents the results of research on the influence of trace compounds from rock salt deicers on portland cement mortar and concrete. An evaluation of the deicers in stock throughout the state showed that about ninety-five percent contained enough sulfate to cause accelerated deterioration of concrete. Of the impurities found in rock salts, sulfate compounds of calcium and magnesium were found to be equally deleterious. Magnesium chloride was found to be innocuous. Introduction of fly ash eliminated the damage to portland cement mortar caused by sulfates. When used with frost resistant Alden aggregate in fly ash concrete and exposed to a variety of deicer brine compositions, the concrete did not deteriorate after exposure. With the exception of a high calcium brine, the behavior of the frost-prone Garrison aggregate was independent of deicer treatment; the high calcium brine reduced frost damage with this aggregate. Two approaches to reducing sulfate deterioration from deicers are suggested as (1) limiting the amount of sulfate to about 0.28 percent, and (2) making concrete sulfate-resistant by using fly ash. Techniques for making existing concrete deicer-sulfate-resistant are essential to a practical solution.

Development of an Economic Dust Palliative for Limestone Surfaced Secondary Roads, HR-297, 1990

This research project was directed at laboratory and field evaluation of sodium montmorillonite clay (bentonite) as a dust palliative for limestone surfaced secondary roads. It had been postulated that the electrically charged surfaces of the clay particles could interact with the charged surfaces of the limestone and act as a bonding agent to agglomerate fine (-#200) particulates and also to band the fine particulates to larger (+#200) limestone particles. Laboratory testing using soda ash dispersed bentonite treatment of limestone fines indicated significant improvement of compressive strength and slaking characteristics. It was recommended that the project proceed to field trials and test roads were constructed in Dallas and Adair counties in Iowa. Soda ash dispersed bentonite solutions can be field mixed and applied with conventional spray distribution equipment. A maximum of 1.5% bentonite(by weight of aggregate)can be applied at one time. Higher applications would have to be staged allowing the excess moisture to evaporate between applications. Construction of higher application treatments can be accomplished by adding dry bentonite to the surfacing material and then by dry road mixing. The soda ash water solution can then be spray applied and the treated surfacing material wet mixed by motor graders to a consistency of 3 to 4 inch slump concrete. Two motor graders working in tandem can provide rapid mixing for both methods of construction. Calcium and magnesium chloride treatments are 2 to 3 times more effective in dust reduction in the short term (3-4 months) but are prone to washboarding and potholing due to maintenance restrictions. Bentonite treatment at the 2-3% level is estimated to provide a 30-40% dust reduction over the long term(18-24 months). Normal maintenance blading operations can be used on bentonite treated areas. Vehicle braking characteristics are not adversely affected up to the 3.0% treatment level. The bentonite appears to be functioning as a banding agent to bind small particulates to larger particles and is acting to agglomerate fine particles of limestone. This bonding capability appears recoverable from environmental effects of winter, and from alternating wet and dry periods. The bentonite appears to be able to interact with new applications of limestone maintenance material and maintains a dust reduction capability. Soda ash dispersed bentonite treatment is approximately 10 times more cost effective per percent dust reduction than conventional chloride treatments with respect to time. However,the disadvantage is that there is not the initial dramatic reduction in dust generation as with the chloride treatment. Although dust is reduced 30-40% after treatment there is still dust being generated and the traveling public or residents may not perceive the reduction.

Deicing Salt Corrosion with and without Inhibitors, MLR-87-8, 1989

Chloride ion penetration through concrete to reinforcing steel is causing the premature deterioration of numerous bridge decks in Iowa. The purpose of the research reported in this paper was to determine whether any of several additives or alternative deicing chemicals could inhibit corrosion of reinforcing steel. The deicers tested were calcium magnesium acetate (CMA), CMA plus NaCl (NaCl: sodium chloride), Quicksalt plus PCI, and CG-90, a polyphosphate solution being developed by Cargill. Two tests were established. First, steel coupons were placed in a 15% solution of a deicer and distilled water to determine which alternative deicer would cause the least amount of corrosion in solution. The coupons were weighed periodically to determine each coupon's weight loss from corrosion. The second test involved ponding a 15% solution of each material on reinforced concrete blocks. Weekly copper-copper sulfate electrical half-cell (CSE) potential readings were taken on each block to determine whether corrosive activity was occurring at the steel surface. When the ponding research was concluded, concrete samples were taken from one of the three blocks ponded with each deicer. The samples were used to determine the chloride ion content at the level of the steel. Results show that all the deicers were less corrosive than NaCl. Only pure CMA, however, significantly inhibited the corrosion of steel embedded in concrete.

Lack of the alanine-serine-cysteine transporter 1 causes tremors, seizures, and early postnatal death in mice.

The Na(+)-independent alanine-serine-cysteine transporter 1 (Asc-1) is exclusively expressed in neuronal structures throughout the central nervous system (CNS). Asc-1 transports small neutral amino acids with high affinity especially for D-serine and glycine (K(i): 8-12 microM), two endogenous glutamate co-agonists that activate N-methyl-D-aspartate (NMDA) receptors through interacting with the strychnine-insensitive glycine binding-site. By regulating D-serine (and possibly glycine) levels in the synaptic cleft, Asc-1 may play an important role in controlling neuronal excitability. We generated asc-1 gene knockout (asc-1(-/-)) mice to test this hypothesis. Behavioral phenotyping combined with electroencephalogram (EEG) recordings revealed that asc-1(-/-) mice developed tremors, ataxia, and seizures that resulted in early postnatal death. Both tremors and seizures were reduced by the NMDA receptor antagonist MK-801. Extracellular recordings from asc-1(-/-) brain slices indicated that the spontaneous seizure activity did not originate in the hippocampus, although, in this region, a relative increase in evoked synaptic responses was observed under nominal Mg(2+)-free conditions. Taken together with the known neurochemistry and neuronal distribution of the Asc-1 transporter, these results indicate that the mechanism underlying the behavioral hyperexcitability in mutant mice is likely due to overactivation of NMDA receptors, presumably resulting from elevated extracellular D-serine. Our study provides the first evidence to support the notion that Asc-1 transporter plays a critical role in regulating neuronal excitability, and indicate that the transporter is vital for normal CNS function and essential to postnatal survival of mice.

Typologie des sols sur gypse et végétation associée en Suisse

Soils on gypsum are well known in dry climates, but were very little described in temperate climate, and never in Switzerland. This study aims to describe soils affected by gypsum in temperate climate and to understand their pedogenesis using standard laboratory analyzes performed on ten Swiss soils located on gypsum outcrops. In parallel, phytosociological relevés described the vegetation encountered in gypsiferous grounds. Gypsification process (secondary gypsum enrichment by precipitation) was observed in all soils. It was particularly important in regions where potential evapotranspiration exceed strongly precipitations in summer (central Valais, Chablais under influence of warm wind). Gypsum contents were regularly measured above 20% in deep horizons, and exceeded locally 70%, building a white, indurate horizon. However, the absence of such a gypsic horizon in the top soil hindered the use of gypsosol (according to the Référentiel pédologique, BAIZE & GIRARD 2009), the typical name of soils affected by gypsum, but restricted to dry regions. As all soils had a high content of magnesium carbonates, they were logically classified in the group of DOLOMITOSOLS. However, according to the World Reference Base for Soil Resources (IUSS 2014), five soils can be classified among the Gypsisols, criteria being here less restricting. These soils are characterized by a coarse texture and a particulate brittle structure making a filtering substrate. They allow water to flow easily taking nutrients. They are not retained by clay, which does generally not exceed 1% of the fine material. The saturation of calcium blocks the breakdown of organic matter. Moreover, these soils are often rejuvenated by erosion caused by the rough relief due to gypsum (landslides, sinkholes, cliffs and slopes). Hence, the vegetation is mainly characterized by calcareous and drought tolerant species, with mostly xerothermophilic beech (Cephalanthero-Fagenion) and pine forests (Erico-Pinion sylvestris) in lowlands, or subalpine heathlands (Ericion) and dry calcareous grasslands (Caricion firmae) in higher elevations.

The Relationship of Ferroan Dolomite Aggregate to Rapid Concrete Deterioration, HR-266, 1987

Some of Iowa's 13,200 miles of portland cement concrete (pcc) pavement have remained structurally sound for over 50 years while others have suffered premature deterioration. Research has shown that the type of coarse aggregate used in the pcc is the major cause of this premature deterioration. Some coarse aggregates for concrete exhibit a nonuniform performance history. They contribute to premature deterioration on heavily salted primary roadways while providing long maintenance-free life on unsalted secondary pavements. This inconsistency supports the premise that there are at least two mechanisms that contribute to the deterioration. Previous research has shown that one of these mechanisms is a bad pore system. The other is apparently a chemical reaction. The objective of this research is to develop simple rapid test methods to predict the durability of carbonate aggregate in pcc pavement. X-ray diffraction analyses of aggregate samples have been conducted on various beds from numerous quarries producing diffraction plots for more than 200 samples of dolomitic or dolomite aggregates. The crystalline structures of these dolomitic aggregates show maximum-intensity dolomite/ankerite peaks ranging from a d-spacing of 2.884 angstroms for good aggregates to a d-spacing of 2.914 angstroms for nondurable aggregates. If coarse aggregates with known bad pore systems are removed from this summary, the d-spacing values of the remaining aggregates correlate very well with expected service life. This may indicate that the iron substitution for magnesium in the dolomite crystal is associated with the instability of the ferroan dolomite aggregates in pcc pavement.

Air Content and Permeability of PCC Pavements: 1909 to 2006, MLR-05-02, 2007

Portland cement concrete pavements have given excellent service history for Iowa. Many of these pavements placed during the 1920’s and 1930’s are still in service today. Many factors go in to achieve a long term durable concrete pavement. Probably the most important is the durability of the aggregate. Until the 1930’s, pit run gravel was the most predominant aggregate used. Many of these gravels provided long term performance and their durability is dependent upon the carbonate fraction of the gravel. Later, limestone (calcium carbonate) and dolomite (calcium, magnesium carbonate) sources were mined across Iowa. The durability of these carbonate aggregates is largely dependent upon the pore system which can cause freeze thaw problems known as D-cracking, which was a problem with some sources during the 1960’s. Also, some of these carbonate aggregates are also susceptible to deterioration from deicing salts. Geologists have identified the major components that affect the durability of these carbonate aggregates and sources are tested to ensure long term performance in Portland cement concrete. Air entrainment was originally put in concrete to improve scaling resistance. It is well known that air entrainment is required to provide freeze thaw protection in concrete pavements today. In Iowa, air entrainment was not introduced in concrete pavements until 1952. This research investigates properties that made older concrete pavements durable without air entrainment.

The Deleterious Chemical Effects of Concentrated Deicing Solutions on Portland Cement Concrete, TR-480, 2008

This research project investigated the effects of concentrated brines of magnesium chloride, calcium chloride, sodium chloride, and calcium magnesium acetate on portland cement concrete. Although known to be effective at deicing and anti-icing, the deleterious effects these chemicals may have on concrete have not been well documented. As a result of this research, it was determined that there is significant evidence that magnesium chloride and calcium chloride chemically interact with hardened portland cement paste in concrete resulting in expansive cracking, increased permeability, and a significant loss in compressive strength. Although the same effects were not seen with sodium chloride brines, it was shown that sodium chloride brines have the highest rate of ingress into hardened concrete. This latter fact is significant with respect to corrosion of embedded steel. The mechanism for attack of hardened cement paste varies with deicer chemical but in general, a chemical reaction between chlorides and cement hydration products results in the dissolution of the hardened cement paste and formation of oxychloride phases, which are expansive. The chemical attack of the hardened cement paste is significantly reduced if supplementary cementitious materials are included in the concrete mixture. Both coal fly ash and ground granulated blast furnace slag were found to be effective at mitigating the chemical attack caused by the deicers tested. In the tests performed, ground granulated blast furnace slag performed better as a mitigation strategy as compared to coal fly ash. Additionally, siloxane and silane sealants were effective at slowing the ingress of deicing chemicals into the concrete and thereby reducing the observed distress. In general, the siloxane sealant appeared to be more effective than the silane, but both were effective and should be considered as a maintenance strategy.

The Deleterious Chemical Effects of Concentrated Deicing Solutions on Portland Cement Concrete, TR-480, Implementation Guide, 2008

This research project investigated the effects of concentrated brines of magnesium chloride, calcium chloride, sodium chloride, and calcium magnesium acetate on portland cement concrete. Although known to be effective at deicing and anti-icing, the deleterious effects these chemicals may have on concrete have not been well documented. As a result of this research, it was determined that there is significant evidence that magnesium chloride and calcium chloride chemically interact with hardened portland cement paste in concrete resulting in expansive cracking, increased permeability, and a significant loss in compressive strength. Although the same effects were not seen with sodium chloride brines, it was shown that sodium chloride brines have the highest rate of ingress into hardened concrete. This latter fact is significant with respect to corrosion of embedded steel. The mechanism for attack of hardened cement paste varies with deicer chemical but in general, a chemical reaction between chlorides and cement hydration products results in the dissolution of the hardened cement paste and formation of oxychloride phases, which are expansive. The chemical attack of the hardened cement paste is significantly reduced if supplementary cementitious materials are included in the concrete mixture. Both coal fly ash and ground granulated blast furnace slag were found to be effective at mitigating the chemical attack caused by the deicers tested. In the tests performed, ground granulated blast furnace slag performed better as a mitigation strategy as compared to coal fly ash. Additionally, siloxane and silane sealants were effective at slowing the ingress of deicing chemicals into the concrete and thereby reducing the observed distress. In general, the siloxane sealant appeared to be more effective than the silane, but both were effective and should be considered as a maintenance strategy.

The Deleterious Chemical Effects of Concentrated Deicing Solutions on Portland Cement Concrete, TR-480, Executive Summary, 2008

This research project investigated the effects of concentrated brines of magnesium chloride, calcium chloride, sodium chloride, and calcium magnesium acetate on portland cement concrete. Although known to be effective at deicing and anti-icing, the deleterious effects these chemicals may have on concrete have not been well documented. As a result of this research, it was determined that there is significant evidence that magnesium chloride and calcium chloride chemically interact with hardened portland cement paste in concrete resulting in expansive cracking, increased permeability, and a significant loss in compressive strength. Although the same effects were not seen with sodium chloride brines, it was shown that sodium chloride brines have the highest rate of ingress into hardened concrete. This latter fact is significant with respect to corrosion of embedded steel. The mechanism for attack of hardened cement paste varies with deicer chemical but in general, a chemical reaction between chlorides and cement hydration products results in the dissolution of the hardened cement paste and formation of oxychloride phases, which are expansive. The chemical attack of the hardened cement paste is significantly reduced if supplementary cementitious materials are included in the concrete mixture. Both coal fly ash and ground granulated blast furnace slag were found to be effective at mitigating the chemical attack caused by the deicers tested. In the tests performed, ground granulated blast furnace slag performed better as a mitigation strategy as compared to coal fly ash. Additionally, siloxane and silane sealants were effective at slowing the ingress of deicing chemicals into the concrete and thereby reducing the observed distress. In general, the siloxane sealant appeared to be more effective than the silane, but both were effective and should be considered as a maintenance strategy.

Quantification of magmatic and hydrothermal processes in a peralkaline syenite-alkali granite complex based on textures, phase equilibria, and stable and radiogenic isotopes

The Puklen complex of the Mid-Proterozoic Gardar Province, South Greenland, consists of various silica-saturated to quartz-bearing syenites, which are intruded by a peralkaline granite. The primary mafic minerals in the syenites are augite +/- olivine + Fe-Ti oxide + amphibole. Ternary feldspar thermometry and phase equilibria among mafic silicates yield T = 950-750degreesC, a(SiO2) = 0.7-1 and an f(O2) of 1-3 log units below the fayalite-magnetite-quartz (FMQ) buffer at 1 kbar. In the granites, the primary mafic minerals are ilmenite and Li-bearing arfvedsonite, which crystallized at temperatures below 750degreesC and at f(O2) values around the FMQ buffer. In both rock types, a secondary post-magmatic assemblage overprints the primary magmatic phases. In syenites, primary Ca-bearing minerals are replaced by Na-rich minerals such as aegirine-augite and albite, resulting in the release of Ca. Accordingly, secondary minerals include ferro-actinolite, (calcite-siderite)(ss), titanite and andradite in equilibrium with the Na-rich minerals. Phase equilibria indicate that formation of these minerals took place over a long temperature interval from near-magmatic temperatures down to similar to300degreesC. In the course of this cooling, oxygen fugacity rose in most samples. For example, late-stage aegirine in granites formed at the expense of arfvedsonite at temperatures below 300degreesC and at an oxygen fugacity above the haematite-magnetite (HM) buffer. The calculated delta(18)O(melt) value for the syenites (+5.9 to +6.3parts per thousand) implies a mantle origin, whereas the inferred delta(18)O(melt) value of <+5.1parts per thousand for the granitic melts is significantly lower. Thus, the granites require an additional low-delta(18)O contaminant, which was not involved in the genesis of the syenites. Rb/Sr data for minerals of both rock types indicate open-system behaviour for Rb and Sr during post-magmatic metasomatism. Neodymium isotope compositions (epsilonNd(1170 Ma) = -3.8 to -6.4) of primary minerals in syenites are highly variable, and suggest that assimilation of crustal rocks occurred to variable extents. Homogeneous epsilon(Nd) values of -5.9 and -6.0 for magmatic amphibole in the granites lie within the range of the syenites. Because of the very similar neodymium isotopic compositions of magmatic and late- to post-magmatic minerals from the same syenite samples a principally closed-system behaviour during cooling is implied. In contrast, for the granites an externally derived fluid phase is required to explain the extremely low epsilon(Nd) values of about -10 and low delta(18)O between +2.0 and +0.5parts per thousand for late-stage aegirine, indicating an open system in the late-stage history. In this study we show that the combination of phase equilibria constraints with stable and radiogenic isotope data on mineral separates can provide much better constraints on magma evolution during emplacement and crystallization than conventional whole-rock studies.

Blue luminescence at room temperature in defective MgO films

Luminescence spectroscopy has been used to characterize MgO films prepared by rf-sputtering. A clear correlation is found between the appearance of an emission peak centered at approximately 460 nm and the detection of ferromagnetic ordering in the samples. We suggest that cationic vacancies are responsible for the blue-light emission by introducing p states into the electronic band-gap. In accordance with this, our results strongly indicate that cationic vacancies are at the heart of the appearance of long-range magnetic ordering in MgO films.

The Deleterious Chemical Effects of Concentrated Deicing Solutions on Portland Cement Concrete, Literature Review, TR-480, 2008

This research project investigated the effects of concentrated brines of magnesium chloride, calcium chloride, sodium chloride, and calcium magnesium acetate on portland cement concrete. Although known to be effective at deicing and anti-icing, the deleterious effects these chemicals may have on concrete have not been well documented. As a result of this research, it was determined that there is significant evidence that magnesium chloride and calcium chloride chemically interact with hardened portland cement paste in concrete resulting in expansive cracking, increased permeability, and a significant loss in compressive strength. Although the same effects were not seen with sodium chloride brines, it was shown that sodium chloride brines have the highest rate of ingress into hardened concrete. This latter fact is significant with respect to corrosion of embedded steel. The mechanism for attack of hardened cement paste varies with deicer chemical but in general, a chemical reaction between chlorides and cement hydration products results in the dissolution of the hardened cement paste and formation of oxychloride phases, which are expansive. The chemical attack of the hardened cement paste is significantly reduced if supplementary cementitious materials are included in the concrete mixture. Both coal fly ash and ground granulated blast furnace slag were found to be effective at mitigating the chemical attack caused by the deicers tested. In the tests performed, ground granulated blast furnace slag performed better as a mitigation strategy as compared to coal fly ash. Additionally, siloxane and silane sealants were effective at slowing the ingress of deicing chemicals into the concrete and thereby reducing the observed distress. In general, the siloxane sealant appeared to be more effective than the silane, but both were effective and should be considered as a maintenance strategy.