Dating archeological ceramics from the Valley of Vitor, Arequipa by the TL method

The age of some ancient pottery from the Valley of Vitor in the region of Arequipa, Peru, is determined by the thermoluminescence (TL) method. For dating, a 325 degrees C TL peak was used and irradiation with -dose from 5 to 50Gy was carried out for the additive method, and from 0.4 to 5Gy for the regeneration method. For these dose values, the TL intensity is observed to grow linearly, obtaining an accumulated dose of 1.62 +/- 0.09Gy and 1.36 +/- 0.03Gy for the additive and regeneration methods, respectively. The age (A) of the sample was calculated by the two methods, being A=867 +/- 195 years after Christ (AC) for the additive method and A=1050 +/- 157 years AC for the regeneration method. Both results are within 800-1200 years AC, which is the period of the Wari culture.

Chemical process to separate iron oxides particles in pottery sample for EPR dating

Ancient potteries usually are made of the local clay material, which contains relatively high concentration of iron. The powdered samples are usually quite black, due to magnetite, and, although they can be used for thermoluminescene (TL) dating, it is easiest to obtain better TL reading when clearest natural or pre-treated sample is used. For electron paramagnetic resonance (EPR) measurements, the huge signal due to iron spin-spin interaction, promotes an intense interference overlapping any other signal in this range. Sample dating is obtained by dividing the radiation dose, determined by the concentration of paramagnetic species generated by irradiation, by the natural dose so as a consequence, EPR dating cannot be used, since iron signal do not depend on radiation dose. In some cases, the density separation method using hydrated solution of sodium polytungstate [Na(G)(H(2)W(12)O(40))center dot H(2)O] becomes useful. However, the sodium polytungstate is very expensive in Brazil: hence an alternative method for eliminating this interference is proposed. A chemical process to eliminate about 90% of magnetite was developed. A sample of powdered ancient pottery was treated in a mixture (3:1:1) of HCI, HNO(3) and H(2)O(2) for 4 h. After that, it was washed several times in distilled water to remove all acid matrixes. The original black sample becomes somewhat clearer. The resulting material was analyzed by plasma mass spectrometry (ICP-MS), with the result that the iron content is reduced by a factor of about 9. In EPR measurements a non-treated natural ceramic sample shows a broad spin-spin interaction signal, the chemically treated sample presents a narrow signal in g= 2.00 region, possibly due to a radical of (SiO(3))(3-), mixed with signal of remaining iron [M. lkeya, New Applications of Electron Spin Resonance, World Scientific, Singapore, 1993, p. 285]. This signal increases in intensity under -gamma-irradiation. However, still due to iron influence, the additive method yielded too old age-value. Since annealing at 300 degrees C, Toyoda and Ikeya IS. Toyoda, M. Ikeya, Geochem. J. 25 (1991) 427-445] states that E `(1)-signal with maximum intensity is obtained, while annealing at 400 degrees C E`(1)-signal is completely eliminated, the subtraction of the second one from 300 degrees C heat-treated sample isolate E`(1)-like signal. Since this is radiation dose-dependent, we show that now EPR dating becomes possible. (C) 2008 Elsevier B.V. All rights reserved.

Structural role of fluoride in the ion-conducting glass system B(2)O(3)-PbO-LiF studied by single- and double-resonance NMR

The local structure of an ion-conducting glass with nominal composition 50B(2)O(3)-10PbO-40LiF has been investigated by complementary (7)Li, (11)B, (19)F, and (207)Pb single- and double-resonance experiments. The results give insight into the structural role of the lithium fluoride additive in borate glasses: (1) LiF is seen to actively participate in the network transformation process contributing to the conversion of three- into four-coordinate boron units, as shown by (11)B single-resonance as well as by (11)B{(19)F} and (19)F{(11)B} double-resonance experiments. (2) (19)F signal quantification experiments suggest substantial fluoride loss, presumably caused by formation of volatile BF(3). A part of the fluoride remains in the dopant role, possibly in the form of small LiF-like cluster domains, which serve as a mobile ion supply. (3) The extent of lithium-fluorine and lead-fluorine interactions has been characterized by (7)Li{(19)F} and (207)Pb{(19)F} REDOR and SEDOR experiments. On the basis of these results, a quantitative structural description of this system has been developed.

Contravariantly finite subcategories closed under predecessors

Let A be an Artin algebra and mod A be the category of finitely generated right A-modules. We prove that an additive full subcategory C of mod A closed under predecessors is contravariantly finite if and only if its right Ext-orthogonal is covariantly finite, or if and only if the Ext-injectives in C define a cotilting module (over the support algebra of C) or, equivalently, if and only if C is the support of the representable functors given by the Ext-injectives. (C) 2009 Elsevier Inc. All rights reserved.

Co-stressors chilling and high light increase photooxidative stress in diuron-treated red alga Kappaphycus alvarezii but with lower involvement of H(2)O(2)

Diuron is one of the most commonly found N-phenylurea herbicides in marine/estuarine waters that promotes toxic effects by inhibiting photosynthesis and affecting the production of reactive oxygen species (ROS) in autotrophs. Since photo- and thermoacclimation are also ROS-mediated processes, this work evaluates a hypothetical additive effect of high light (HL) and chilling (12 degrees C) on 50 nM diuron toxicity to the highly-photosynthetically active apices of the red alga Kappaphycus alvarezii. Additive inhibition of photosynthesis was mainly evidenced by significant decreases of quantum yield of photosystem II and electron transfer rates upon co-stressors exposure to diuron-treated algae. Under extreme 12 degrees C/HL/diuron conditions, unexpected lower correlations between H(2)O(2) concentrations in seawater and radical-sensitive protein thiols were concomitantly measured with the highest indexes of photoinhibition (parameter beta). Altogether, these data support the hypothesis that co-stressors chilling/HL additively inhibit photosynthesis in diuron-exposed K. alvarezii but with less involvement of H(2)O(2) in injury effects than with only chilling or HL. (C) 2010 Elsevier Inc. All rights reserved.

Application of Microelectrode Voltammetry to Study the Properties of Surfactant Solutions: Alkyltrimethylammonium Bromides

Microelectrode cyclic voltammetry (MV) has been employed to investigate the micellar properties of solutions of homologous alkyltrimethylammonium bromides, RMe(3)ABr, R = C(10), C(12), and C(14), in water and in the presence of added NaBr. The micellar self-diffusion coefficient was calculated from the limiting current for the reversible electron transfer of micelle-bound ferrocene. From the values of this property, other parameters were calculated, including the micellar hydrodynamic radius, RH, and aggregation number, N(agg); the latter was also theoretically calculated. We determined the values of the diffusion coefficient as a function of various experimental variables and observed the following trends: The diffusion coefficient decreases as a function of increasing surfactant concentration (no additional electrolyte added); it decreases as a function of increasing surfactant concentration at fixed NaBr concentration; and it shows a complex dependence (increase then decrease) on the NaBr concentration at a fixed RMe(3)ABr concentration. The value of the intermicellar interaction parameter decreases and then increases as a function of increasing NaBr concentration. These results are discussed in terms of intermicellar,interactions and the effect of NaBr on the micellar surface charge density and sphere-to-rod geometry change. The NaBr concentration required to induce the latter change increases rapidly as a function of decreasing the length of R: no geometry change was detected for C(10)Me(3)ABr. Values of N(agg) increase as I function of increasing the length of R and are in good agreement with both literature values and values that were calculated theoretically. Thus, MV is a convenient and simple technique for obtaining fundamental properties of surfactant solutions, including additive-induced changes of micellar parameters (N(agg)) and morphology changes.

Effect of Calcium Pre-rinse and Fluoride Dentifrice on Enamel and on Dental Plaque Formed In Situ

Purpose: The aim of this in situ double-blind randomised crossover study was to investigate the effect of calcium (Ca) pre-rinse on the composition of plaque and on enamel prior to the use of fluoride (F) dentifrice. Materials and Methods: During four phases (14 days each) of this study, 10 volunteers had agreed to wear dental appliances containing two healthy bovine enamel blocks. A fresh solution containing 20% weight/volume (w/v) sucrose was dripped on the enamel blocks ex vivo for 5 min three times a day. Subsequently, the appliances were replaced in the mouth, and the volunteers rinsed their mouth with 10 mL of a Ca (150 mmol/L) or a placebo rinse (1 min). In sequence, a slurry (1:3 w/v) of F (1030 ppm) or placebo dentifrice was dripped onto the blocks ex vivo for 1 min. During this time, the volunteers brushed their teeth with the respective dentifrice. The appliances were replaced in the mouth, and the volunteers rinsed their mouth with water. The plaque formed on the blocks was analysed for F and Ca. The enamel demineralisation as well as the incorporation of F on enamel was evaluated by cross-sectional microhardness and alkali-soluble F analysis, respectively. Data were tested using analysis of variance (P < 0.05). Results: The Ca pre-rinse prior to the use of the F dentifrice led to a three- and sixfold increase in the plaque F and Ca concentrations, respectively. It also did not have any additive effect on the F content on the enamel and the demineralisation of the enamel, in comparison with the use of F dentifrice alone. Conclusions: A Ca lactate rinse used prior to the F dentifrice was able to change the mineral content in the plaque, but it was unable to prevent enamel demineralisation.

A convenient synthetic route for alkynylselenides from alkynyl bromides and diaryl diselenides employing copper(I)/imidazole as novel catalyst system

A mild, convenient, and effective strategy is developed for the synthesis of alkynyl selenides from alkynyl bromides and respective diselenides using Cul/imidazole as a novel catalyst system with Mg as additive. The Procedure affords the title compounds in moderate to good yield (51-89%). The main advantages of the protocol include the use of inexpensive copper catalyst, a novel Cu(I)/imidazole combination, and good yield of the products. (C) 2008 Elsevier Ltd. All rights reserved.

Effect of mechanical coating with Ni and Ni-5% Al on the structure and electrochemical properties of the Mg-50% Ni alloy

The Mg-Ni metastable alloys (with amorphous or nanocrystalline structures) are promising candidates for anode application in nickel-metal hydride rechargeable batteries due to its large hydrogen absorbing capacity, low weight, availability, and relative low price. In spite of these interesting features, improvement on the cycle life performance must be achieved to allow its application in commercial products. In the present paper, the effect of mechanical coating of a Mg-50 at.% Ni alloy with Ni and Ni-5 at.% Al on the structure, powder morphology, and electrochemical properties is investigated. The coating additives, Mg-Ni alloy and resulting nanocomposites (i.e., Mg-Ni alloy + additive) were investigated by means of X-ray diffraction and scanning electron microscopy. The Mg-Ni alloy and nanocomposites were submitted to galvanostatic cycles of charge and discharge to evaluate their electrode performances. The mechanical coating with Ni and Ni-5% Al increased the maximum discharge capacity of the Mg-Ni alloy from of 221 to 257 and 273 mA h g(-1), respectively. Improvement on the cycle life performance was also achieved by mechanical coating.

SEM, EPR and ToF-SIMS analyses applied to unravel the technology employed for pottery-making by pre-colonial Indian tribes from Pantanal, Brazil

The present work aims at elucidating the technology applied in the fabrication of ceramic objects by the ancient ceramists that inhabited the western border of Pantanal, Mato-Grosso do Sul, with the help of a multidisciplinary approach making use of chemical and physical methods of analysis. The potshards under study show the presence of different types of additives, as determined by scanning electron microscopy (SEM) and time of flight secondary ion mass spectrometry (ToF-SIMS). The dispersion of the additives within the ceramic matrix was also addressed by SEM, which shed light on the mounting technique used by the potters to assemble the ceramic vessels. Moreover, the tensile strength conferred to the pottery by the use of a specific type of additive was evaluated by applying a mechanical test. These results were correlated with the firing temperature of the potshards, determined by means of electron paramagnetic resonance (EPR). (C) 2010 Elsevier Ltd. All rights reserved.

Print quality study of a laboratory offset press

PAPRO operates within the Forest Research company and their mission is to develop value-addingindustry solutions. At present there are no good ways for mills to easily test the printing quality on newsprintpaper. There is a great need for a fast way to do this on different paper qualities; with a laboratory-offset press this can be both a time and money saving method. At PAPRO Forest Research, NewZealand, a laboratory offset press has been developed and designed, during the past seven years, concerningthis issue. Earlier projects were made concerning the press, e.g. to establish the optimal settings.The mission with this project was to partly determine the present variability of the print quality andto evaluate if the fountain solution, distilled water and 2% Diol green concentrate, used at the momentmixed with different percentages of Isopropanol could decrease the variability and contribute to morestabile results. Throughout the whole project the print quality showed a high variation and was evenmore variable when the Isopropanol was added. All in all 50 print rounds times twelve printed paperstrips was carried out through the project divided into three parts. To analyse the print quality, amicroscope with an image capture camera has been used. Data from the taken images was analysedand inserted into charts to see the variations.The conclusions of the whole project are not satisfying because no final evaluations were possible tomake. Main conclusions are that the additive of Isopropanol to the ordinary fountain solution, used atpresent, only contributed to more unstable results of the print quality. And it seems to be difficult toget some stable results from the lab press as long as the room where it is placed is not fully conditionedas required for the process of offset printing. And the fact that the airbrush which applies theamount of fountain solution is also variable, as shown in earlier projects, which contributes to unstableresults as well. For further work more exact parameters as a conditioned room are required and thepossibility to further design the laboratory press to use waterless offset printing instead.

Genetic Control of Residual Variance for Teat Number in Pigs

The genetic improvement in litter size in pigs has been substantial during the last 10-15 years. The number of teats on the sow must increase as well to meet the needs of the piglets, because each piglet needs access to its own teat. We applied a genetic heterogeneity model on teat numberin sows, and estimated medium-high heritability for teat number (0.5), but low heritability for residual variance (0.05), indicating that selection for reduced variance might have very limited effect. A numerically positive correlation (0.8) between additive genetic breeding values for mean and for variance was found, but because of the low heritability for residual variance, the variance will increase very slowly with the mean.

Modelling dominance in a flexible intercross analysis

The aim of this paper is to develop a flexible model for analysis of quantitative trait loci (QTL) in outbred line crosses, which includes both additive and dominance effects. Our flexible intercross analysis (FIA) model accounts for QTL that are not fixed within founder lines and is based on the variance component framework. Genome scans with FIA are performed using a score statistic, which does not require variance component estimation. RESULTS: Simulations of a pedigree with 800 F2 individuals showed that the power of FIA including both additive and dominance effects was almost 50% for a QTL with equal allele frequencies in both lines with complete dominance and a moderate effect, whereas the power of a traditional regression model was equal to the chosen significance value of 5%. The power of FIA without dominance effects included in the model was close to those obtained for FIA with dominance for all simulated cases except for QTL with overdominant effects. A genome-wide linkage analysis of experimental data from an F2 intercross between Red Jungle Fowl and White Leghorn was performed with both additive and dominance effects included in FIA. The score values for chicken body weight at 200 days of age were similar to those obtained in FIA analysis without dominance. CONCLUSION: We have extended FIA to include QTL dominance effects. The power of FIA was superior, or similar, to standard regression methods for QTL effects with dominance. The difference in power for FIA with or without dominance is expected to be small as long as the QTL effects are not overdominant. We suggest that FIA with only additive effects should be the standard model to be used, especially since it is more computationally efficient.

An Experimental Study of Submerged Entry Nozzles (SEN) Focusing on Decarburization and Clogging

The submerged entry nozzle (SEN) is used to transport the molten steel from a tundish to a mould. The main purpose of its usage is to prevent oxygen and nitrogen pick-up by molten steel from the gas. Furthermore, to achieve the desired flow conditions in the mould. Therefore, the SEN can be considered as a vital factor for a stable casting process and the steel quality. In addition, the steelmaking processes occur at high temperatures around 1873 K, so the interaction between the refractory materials of the SEN and molten steel is unavoidable. Therefore, the knowledge of the SEN behaviors during preheating and casting processes is necessary for the design of the steelmaking processes  The internal surfaces of modern SENs are coated with a glass/silicon powder layer to prevent the SEN graphite oxidation during preheating. The effects of the interaction between the coating layer and the SEN base refractory materials on clogging were studied. A large number of accretion samples formed inside alumina-graphite clogged SENs were examined using FEG-SEM-EDS and Feature analysis. The internal coated SENs were used for continuous casting of stainless steel grades alloyed with Rare Earth Metals (REM). The post-mortem study results clearly revealed the formation of a multi-layer accretion. A harmful effect of the SENs decarburization on the accretion thickness was also indicated. In addition, the results indicated a penetration of the formed alkaline-rich glaze into the alumina-graphite base refractory. More specifically, the alkaline-rich glaze reacts with graphite to form a carbon monoxide gas. Thereafter, dissociation of CO at the interface between SEN and molten metal takes place. This leads to reoxidation of dissolved alloying elements such as REM (Rare Earth Metal). This reoxidation forms the “In Situ” REM oxides at the interface between the SEN and the REM alloyed molten steel. Also, the interaction of the penetrated glaze with alumina in the SEN base refractory materials leads to the formation of a high-viscous alumina-rich glaze during the SEN preheating process. This, in turn, creates a very uneven surface at the SEN internal surface. Furthermore, these uneven areas react with dissolved REM in molten steel to form REM aluminates, REM silicates and REM alumina-silicates. The formation of the large “in-situ” REM oxides and the reaction of the REM alloying elements with the previously mentioned SEN´s uneven areas may provide a large REM-rich surface in contact with the primary inclusions in molten steel. This may facilitate the attraction and agglomeration of the primary REM oxide inclusions on the SEN internal surface and thereafter the clogging. The study revealed the disadvantages of the glass/silicon powder coating applications and the SEN decarburization. The decarburization behaviors of Al2O3-C, ZrO2-C and MgO-C refractory materials from a commercial Submerged Entry Nozzle (SEN), were also investigated for different gas atmospheres consisting of CO2, O2 and Ar. The gas ratio values were kept the same as it is in a propane combustion flue gas at different Air-Fuel-Ratio (AFR) values for both Air-Fuel and Oxygen-Fuel combustion systems. Laboratory experiments were carried out under nonisothermal conditions followed by isothermal heating. The decarburization ratio (α) values of all three refractory types were determined by measuring the real time weight losses of the samples. The results showed the higher decarburization ratio (α) values increasing for MgO-C refractory when changing the Air-Fuel combustion to Oxygen-Fuel combustion at the same AFR value. It substantiates the SEN preheating advantage at higher temperatures for shorter holding times compared to heating at lower temperatures during longer holding times for Al2O3-C samples. Diffusion models were proposed for estimation of the decarburization rate of an Al2O3-C refractory in the SEN. Two different methods were studied to prevent the SEN decarburization during preheating: The effect of an ZrSi2 antioxidant and the coexistence of an antioxidant additive and a (4B2O3 ·BaO) glass powder on carbon oxidation for non-isothermal and isothermal heating conditions in a controlled atmosphere. The coexistence of 8 wt% ZrSi2 and 15 wt% (4B2O3 ·BaO) glass powder of the total alumina-graphite refractory base materials, presented the most effective resistance to carbon oxidation. The 121% volume expansion due to the Zircon formation during heating and filling up the open pores by a (4B2O3 ·BaO) glaze during the green body sintering led to an excellent carbon oxidation resistance. The effects of the plasma spray-PVD coating of the Yttria Stabilized Zirconia (YSZ) powder on the carbon oxidation of the Al2O3-C coated samples were investigated. Trials were performed at non-isothermal heating conditions in a controlled atmosphere. Also, the applied temperature profile for the laboratory trials were defined based on the industrial preheating trials. The controlled atmospheres consisted of CO2, O2 and Ar. The thicknesses of the decarburized layers were measured and examined using light optic microscopy, FEG-SEM and EDS. A 250-290 μm YSZ coating is suggested to be an appropriate coating, as it provides both an even surface as well as prevention of the decarburization even during heating in air. In addition, the interactions between the YSZ coated alumina-graphite refractory base materials in contact with a cerium alloyed molten stainless steel were surveyed. The YSZ coating provided a total prevention of the alumina reduction by cerium. Therefore, the prevention of the first clogging product formed on the surface of the SEN refractory base materials. Therefore, the YSZ plasma-PVD coating can be recommended for coating of the hot surface of the commercial SENs.

Inheritance beyond plain heritability : variance-controlling genes in Arabidopsis thaliana

The phenotypic effect of a gene is normally described by the mean-difference between alternative genotypes. A gene may, however, also influence the phenotype by causing a difference in variance between genotypes. Here, we reanalyze a publicly available Arabidopsis thaliana dataset [1] and show that genetic variance heterogeneity appears to be as common as normal additive effects on a genomewide scale. The study also develops theory to estimate the contributions of variance differences between genotypes to the phenotypic variance, and this is used to show that individual loci can explain more than 20% of the phenotypic variance. Two well-studied systems, cellular control of molybdenum level by the ion-transporter MOT1 and flowering-time regulation by the FRI-FLC expression network, and a novel association for Leaf serration are used to illustrate the contribution of major individual loci, expression pathways, and gene-by-environment interactions to the genetic variance heterogeneity.