Final Melting Temperature Research Articles

High- to ultrahigh-temperature metasomatism related to brine infiltration in the Neoarchean Limpopo Complex: Petrology and phase equilibrium modeling

Fluids associated with granulite-facies metamorphism are considered to have controlled various lower crustal processes such as dehydration/hydration reactions, partial melting, material circulation, and high-temperature metasomatism. Here, we report new petrological data obtained from enderbite and its metasomatized equivalents from the Southern Marginal Zone (SMZ) of the Neoarchean Limpopo Complex, South Africa, and evaluate the alteration process caused by infiltration of high-salinity aqueous fluids during granulite-facies metamorphism. At the study area on Farm Commissiedraai, enderbite (plagioclase+quartz+K-feldspar+orthopyroxene) is partly metasomatized with the formation of continuous alteration zones comprising plagioclase+quartz+K-feldspar+orthopyroxene+garnet, plagioclase+quartz+K-feldspar+garnet, and finally mesoperthite/antiperthite+quartz+garnet+sillimanite. Bulk K2O increases, and CaO, MgO, FeO, and TiO2 decreases continuously from enderbite to the most intensely metasomatized rock. The occurrence of aqueous fluid inclusions with final melting temperatures of −29.2°C to −21.6°C trapped as a primary phase within quartz in the highly altered sample indicates that a high-salinity brine (probably NaCl rich) with additional components such as MgCl2 and CaCl2 controlled metasomatism. We employed a phase equilibrium modeling technique to evaluate the metasomatic process in the system NCKFMASH using THERMOCALC 3.3, and discovered that addition of K to and removal of Ca and Mg from the enderbite gave rise to the metasomatized mineral assemblages. Modeling also indicated that metasomatic alteration occurred at ca. 900°C, which is consistent with post-peak metamorphic conditions reached during the initial stage of exhumation in the SMZ, and with temperature calculations based on ternary-feldspar geothermometry of antiperthite in the highly metasomatized sample. The brine fluid that accompanied metasomatism infiltrated along the high-temperature Petronella Shear Zone, and was probably derived from devolatilization of low-grade greenstone materials of the Kaapvaal Craton as the result of thrusting hot granulite over cool granite-greenstone belts. Our results therefore suggest that metasomatism at this locality occurred closely after the peak metamorphism having been reached at ∼1000°C in the root zone of the Limpopo orogeny at ∼2.72Ga.

Geochemical record of fluid flow and dolomitization of carbonate platforms: ascending freshwater–mesohaline mixing, Miocene of Spain

Abstract This paper constrains fluid flow and chemistry in Miocene dolomites of Spain, where dolomitization has been ascribed to ascending freshwater–mesohaline mixing. End-Miocene dolomite formed as replacement and cement with the same widespread cathodoluminescence. Fluid inclusion final melting temperatures of ice ( T m ice : −0.2 to −2.3 °C) indicate mixing of freshwater and evaporated seawater. δ 18 O and δ 13 C data mostly show positive covariation, and only some have variable δ 13 C and invariant δ 18 O, arguing that mixing was more important than sulphate reduction. Data range from +0.9 to +6.0‰ for δ 18 O and from −4.5 to +3.0‰ for δ 13 C (VPDB (Vienna Pee Dee Belemnite)). Lower stratigraphic units are more depleted isotopically than upper units, suggesting upwards flow of freshwater. 87 Sr/ 86 Sr values (0.70866–0.70904) range from less than to greater than late Miocene seawater. δ 18 O, δ 13 C and Sr analyses show that freshwater interacted with basement, confirming injection of freshwater from below. Upwards flow of freshwater, driven by low density and hydraulic head, created fluid mixing and CO 2 degassing. Comparison of La Molata dolomite to other dolomites of the western Mediterranean suggests that ascending freshwater–mesohaline mixing may be widespread, and that local composition of basement is not the primary driver of dolomitization. The model is broadly applicable to carbonates adjacent to highs, where freshwater discharged into slightly evaporated seawater.

Effect of dietary conjugated linoleic acid supplementation on the technological quality of backfat of pigs

Pigs were fed diets containing 0, 0.25, 0.5 and 1% conjugated linoleic acid (CLA). Compared to controls, backfat from CLA fed pigs was firmer and extracted lipid contained increasing amounts of CLA, but a ±11% overall decrease in unsaturated fatty acids and a ±5% overall increase in each of C16:0 and C18:0 saturated fatty acids were noted. This resulted in a change in the melting properties of fat. The onset setting temperature increased from ±14°C to ±18°C for lipid of backfat of pigs from the 0.25 and 0.5% CLA supplementation groups, and to ±26°C for lipid from the 1% CLA supplementation group. The final melting temperatures increased from ±37°C to ±43°C and ±45°C, respectively. The presence of β′-crystals of C18:0–C16:0–C18:1c9 triacylglycerides in fat from CLA fed pigs and β-crystals in fat from 1% CLA fed pigs was observed. Fatty acid and melting point results explained the improvement in the technological quality of backfat as a result of dietary CLA supplementation.

Thermally Grafting Aminosilane onto Kenaf-Derived Cellulose and Its Influence on the Thermal Properties of Poly(Lactic Acid) Composites

The effects of thermally grafting hydrolysed 3-aminopropyltriethoxysilane (APS) onto kenaf-derived cellulose and the influence of incorporating them into poly(lactic acid) (PLA) were investigated. Composites containing 30 wt.% cellulose (C) and silane-grafted cellulose (SGC) were melt-blended into PLA before being hot pressed into 0.3-mm films. The silane grafting of cellulose was confirmed via Fourier transform infrared spectroscopy (FTIR) with the presence of Si-O-Si, Si-O-cellulose, -Si-C-, and Si-O-C bonds, and –NH2 groups despite post ethanol washing. Using thermogravimetric analysis (TGA), it was determined that the thermal stability of the cellulose improved by 8 °C after silane grafting. As for the composites, PLA/SGC improved the thermal stability by 12 °C as compared to PLA/C. From differential scanning calorimetry (DSC), adding C into PLA slightly reduced the glass transition temperature, Tg, of the PLA from 59 °C to 57 °C, which remained unchanged with silane grafting. PLA displayed double melting peaks from its melt-recrystallization behaviour. While the final melting temperature at 150 °C was not affected, incorporating C and SGC influenced the intensity of the melting peaks. The significant reduction in crystallisation temperature from 113°C to 102 °C and 105 °C, and the increase in crystallinity by almost two fold, indicated that cellulose was an effective nucleating agent.

Hydrocarbon fluid inclusions in the Argo salt, offshore Canadian Atlantic margin

Fluid inclusions hosted in rock salt from the Triassic Argo Formation in the Canadian Atlantic continental margin were studied to investigate the nature and origin of petroleum fluids in them. Inclusions were studied in two wells: Glooscap-C63 and Weymouth-A45. The pillow-shaped salt body intersected by the Glooscap-C63 well is autochthonous, and the salt is transparent and colorless compared with that in the allochthonous, canopy–diaper-shaped body cut by the Weymouth-A45 well which is translucent and buff-colored. Aqueous (AFI), petroleum (PFI), and heterogeneously trapped, mixed petroleum – aqueous (MFI) fluid inclusions were identified using transmitted and fluorescent microscopy, and representative samples were analyzed microthermometrically. Petroleum-bearing fluid inclusions (PFI and MFI) are more common and contain more concentrated petroleum phases in the allochthonous salts of Weymouth-A45 well. Based on microthermometric studies, the AFI and MFI in Glooscap-C63 salt mostly belong to NaCl–H2O and NaCl–H2O–petroleum systems, respectively; in contrast, those of Weymouth-A45 belong to NaCl–MgCl2–H2O and (or) NaCl–CaCl2–H2O and NaCl–MgCl2–H2O–petroleum and (or) NaCl–CaCl2–H2O–petroleum systems, respectively. Each of the AFI, PFI, and MFI types consists of different phases. The medians of Tf (freezing temperature), Tim (initial melting temperature), Te (Eutectic temperature), Tm (final melting (peritectic) temperature), and Th (homogenization temperature) in the AFI and MFI in the salts of Glooscap-C63 well are (−82, −75 °C), (−39, −38 °C), (−25, −24 °C), (−1.8, −3 °C), and (291, 287 °C), respectively. The corresponding medians for the Weymouth-A45 well are (−71, −78 °C), (−52, −52 °C), (−37, −38 °C), (−2.7, −3 °C), and (122, 20 °C), respectively. The median Th of PFI in Glooscap-C63 and Weymouth-A45 salts are 79 and 23 °C, respectively. The most probable source rocks for the petroleum are the shales of the Late Triassic – Early Jurassic Eurydice Formation which is widely distributed at depth underlying the Argo salt.

Crystal structure and thermal behavior of cold-crystallized poly(trimethylene terephthalate)

The structure and thermal behavior of cold-crystallized poly(trimethylene terephthalate) (PTT) are revealed in detail by DSC, AFM, TEM, and WAXD as well as in situ FTIR and SAXS techniques. There is no effect of crystallization temperature and initial state on the crystal modification, yet the morphology is strongly affected by these two factors. First, the small rod-like lamellae for PTT are obtained during the cold crystallization instead of the spherulites formed in the melt crystallization. Second, the edge-on lamellar orientation in thin films is identified during the cold crystallization. The thickness and the lateral width of rod-like lamellae get larger and larger with increasing crystallization temperature. Thin lamellar crystals assemble randomly when the cold-crystallization temperature is lower, while lamellar stacks composed of thicker lamellae are observed when the PTT was annealed at elevated temperature. Moreover, for the cold-crystallized PTT, the final melting temperature does not vary with the crystallization temperature. This phenomenon is explained by the structural improvement during the heating process. For the cold-crystallized PTT sample at lower temperature, three transitions occur when it is heated again: the relaxation of the rigid amorphous phase, the reorganization of molecules in the intermediate phase, and then the melt–recrystallization behavior. Those transitions finally lead to thicker lamellae besides a higher crystallinity before the final fusion. Therefore, the final melting peak of these lamellae is at the same temperature.

Morphological Changes of Linear, Branched Polyethylenes and their Blends during Crystallization and Subsequent Melting by Synchrotron SAXS and DSC

AbstractSummary: The crystalline structure and phase morphology of linear, branched polyethylenes and their blends during crystallization and subsequent melting were investigated, using a combination of differential scanning calorimetry (DSC), and synchrotron small angle X‐ray scattering (SAXS). A linear polyethylene (PE1) with weight‐average molecular weight (Mw) of 114 000 g/mol, and two branched polyethylene copolymers, containing 4.8 mol% (PE4) and 15.3 mol% (PE10) hexane, with molecular weights of 93 000 g/mol and 46 000 g/mol were used as pure samples. Two blends, PE1‐4 and PE1‐10, each with a weight ratio of 50/50, were prepared by solution blending. Our results indicate that in PE4 a phase separation within the branched component itself occurred, forming a broad distribution of lamellar thicknesses during the crystallization process. PE10 on the other hand did hardly crystallize because of the high degree of branching. Co‐crystallization of both components took place in blend PE1‐4 and liquid‐liquid phase separation occurred in the melt of PE1‐10. Morphological parameters were determined by using Bragg's law and the correlation function, respectively. The detected semicrystalline morphology can be well described by the lamellar insertion mode where thin lamellae develop between thicker primary lamellae. During subsequent heating, lamellae melted in the reversed sequence of their formation. The evolution of the structural parameters as a function of temperature revealed that surface melting began at first, and then the complete melting of stacks occurred until the final melting temperature was reached.

Effect of low-level impurities on low-temperature performance properties of biodiesel

Biodiesel, a renewable fuel consisting of fatty acid methyl esters and made from lipid feedstocks, has presented persistent cold weather operability problems that are not predicted using the standards tests common in the petroleum refining industry. These problems have been referred to as “precipitate formation above cloud point” and are known to be caused by minor impurities. This study investigates the fundamental causes of this issue. To this end, water, steryl glucosides (SG), and saturated monoglycerides (SMGs) were spiked into 100% biodiesel (B100) from various feedstock sources. Only SMGs were found to have a significant effect on the cloud point (CP) and final melting temperature (FMT) in four B100 samples with a range of CP. A large difference between FMT and CP indicates that a metastable phase of SMG forms initially and can transform into a more stable, less soluble polymorph over time or upon heating. This occurred for SMG content above approximately 0.2 to 0.3 wt%. For more saturated B100, a large FMT–CP difference was only observed at slower heating rates, suggesting a slower rate of phase transformation. β-monostearin solubility (the most stable phase) in B100 was measured as a function of temperature. CP measurements suggest the metastable phase is as much as 10 times more soluble than the β phase. Differential scanning calorimetry experiments suggest that the metastable phase is a hydrated α-gel. SMGs at concentrations above 0.24 wt% caused failure of the cold soak filtration test (ASTM D7501); however, at higher water concentrations (∼1200 ppm), the effect of SMGs was significantly reduced. Addition of SGs had no effect on cold soak filterability.

Phosphorite-hosted zinc and lead mineralization in the Sekarna deposit (Central Tunisia)

The Sekarna Zn–Pb deposit is located in Central Tunisia at the northeastern edge of the Cenozoic Rohia graben. Mineralization comprises two major ore types: (1) disseminated Zn–Pb sulfides that occur as lenses in sedimentary phosphorite layers and (2) cavity-filling zinc oxides (calamine-type ores) that crosscut Late Cretaceous and Early Eocene limestone. We studied Zn sulfide mineralization in the Saint Pierre ore body, which is hosted in a 5-m-thick sedimentary phosphorite unit of Early Eocene age. The sulfide mineralization occurs as replacements of carbonate cement in phosphorite. The ores comprise stratiform lenses rich in sphalerite with minor galena, Fe sulfides, and earlier diagenetic barite. Laser ablation–inductively coupled plasma mass spectrometry analyses of sphalerite and galena show a wide range of minor element contents with significant enrichment of cadmium in both sphalerite (6,000–20,000 ppm) and galena (12–189 ppm). The minor element enrichments likely reflect the influence of the immediate organic-rich host rocks. Fluid inclusions in sphalerite give homogenization temperatures of 80–130°C. The final ice melting temperatures range from −22°C to −11°C, which correspond to salinities of 15–24 wt.% NaCl eq. and suggest a basinal brine origin for the fluids. Sulfur isotope analyses show uniformly negative values for sphalerite (−11.2‰ to −9.3‰) and galena (−16‰ to −12.3‰). The δ34S of barite, which averages 25.1‰, is 4‰ higher than the value for Eocene seawater sulfate. The sulfur isotopic compositions are inferred to reflect sulfur derivation through bacterial reduction of contemporaneous seawater sulfate, possibly in restricted basins where organic matter was abundant. The Pb isotopes suggest an upper crustal lead source.

Experimental Study of Softening and Melting Properties on Indonesia Vanadium-Titanium Sinters

As a raw material, Indonesia vanadium-titanium sinters are being applied to the blast furnace process for iron making in the typical iron and steel plant. In order to keep the health running of blast furnace process, in this work we have investigated the softening and melting properties of Indonesia vanadium-titanium sinters. We found that the content of vanadium-titanium magnetite in sinter is correlated with the softening and melting ranges for those sinters considered here. With the increasing of the vanadium-titanium magnetite in sinter, the starting softening temperature increases gradually and the final softening temperature increases as well, thereby the softening range becomes narrow. Both starting and final melting temperatures begin to ascent, and the variation of melting range is not obvious. In addition, we also found that the coke is wetted by the molten slag and iron. From the viewpoint of blast furnace process, the softening and melting zone has to move downward. In this zone of blast furnace the contact area of solid-liquid phase will get larger because of the close contract among the molten slag, iron and coke. On one hand, this kind of behavior can definitely speed up the reduction of iron oxide. On the other hand, it simultaneously worse the ventilation properties and affect the normal running of air flow, because a lot of iron and slag can not be got smoothly into the hearth through coke layer.

Dolomite in Permian Paleosols of the Bravo Dome CO2 Field, U.S.A.: Permian Reflux Followed by Late Recrystallization at Elevated Temperature

Abstract Lower Permian Abo–Tubb subsurface strata of northeastern New Mexico, U.S.A. consist of 30 to 120 m of fluvial and eolian deposits, containing numerous dolomitic paleosols. Dolomite in the Abo–Tubb interval occurs in discrete intervals, interpreted as paleosols on the basis of recognizable horizonation and the presence of associated features such as ped structures and rhizoliths. The dolomite commonly forms veins, rhizoliths, and discrete and coalesced nodules. Petrographic analysis indicates four dolomite types present in paleosol horizons: microsparitic, pseudospherulitic, clear cement, and cloudy (inclusion-rich) cement. Microsparitic dolomite constitutes most of (70%) the dolomite, and is stoichiometric, with relatively low Sr and Na and elevated Fe and Mn. Pseudospherulitic dolomite forms 15% of the dolomite, and consists of stoichiometric microspar and spar, with abundant fluid inclusions, low Sr, Na, and Fe, and elevated Mn. Clear dolomite cement constitutes approximately 12% of the dolomite and is finely to coarsely crystalline with a relatively calcian composition, low Sr and Na, and elevated Fe and Mn. The cloudy cement forms a minor (2%) phase of very coarsely crystalline rhombs with a calcian composition, low Sr and Na values, and relatively high Fe and Mn. All dolomite types exhibit a mottled texture of moderate to bright orange and red luminescence. Fluid-inclusion analysis was not possible on the most common (microsparitic) dolomite type, but analyses on the coarser varieties reveal homogenization temperatures typically ranging from 70°C to 110°C and final melting temperatures of ice ranging from −20°C to −34°C, suggesting fluids of high (25% by weight) salinity. Bulk-rock carbon and oxygen isotopes of carbonate nodules and rhizoconcretions from four paleosol profiles most commonly exhibit mean values typically ranging between~ −3 to −5.5‰ (VPDB) and −0.5 to 2.8‰ (VPDB), respectively. Sulfur isotopes were analyzed for the overlying Cimarron Anhydrite interval and an anhydrite nodule near the base of the study interval. Both samples yielded similar results, suggesting that brines that precipitated the Cimarron Anhydrite also influenced the study interval. The dolomite in the Abo–Tubb interval is interpreted to have precipitated in multiple stages. Solid calcite microinclusions in microsparitic and pseudospherulitic dolomite suggest that pedogenensis and groundwater penecontemporaneous with Early Permian deposition led to precipitation of calcite rather than dolomite. Oxygen and sulfur isotope data indicate dolomitization, from later reflux of brines associated with deposition of the overlying (Leonardian) Cimarron Anhydrite. Petrographic relations and elevated temperatures and salinities recorded by the fluid inclusions in the coarse dolomite are consistent with recrystallization of the earlier dolomite and precipitation of dolomite cement from warm saline fluids of a possible Tertiary hydrothermal origin, just predating migration of mantle-derived gas into the Bravo Dome reservoir. These findings offer insight into questions about the climate significance of dolomite in paleosols, origin of dolomite in hydrothermally altered hydrocarbon reservoirs, and the long-term effect of CO2 sequestration in saline aquifers. The results show that dolomitic nodules in paleosols may form as replacements of paleosol calcite long after the paleosol formed. Primary pedogenic dolomite would undoubtedly have climatic and paleoenvironmental significance, but recognizing it as forming during soil formation, as opposed to later dolomitization, is key in establishing that significance. Also, this study provides an example of high-temperature recrystallization of low-temperature dolomite, a process hotly debated in discussions of dolomitized hydrocarbon reservoirs with evidence for hydrothermal fluid flow. Finally, as a natural CO2 reservoir, the Bravo Dome system shows that the long-term result of dissolution of CO2 into brines is predominantly carbonate mineral dissolution.

Geology, geochemistry, and genesis of Axi: A Paleozoic low-sulfidation type epithermal gold deposit in Xinjiang, China

Axi is a low-sulfidation type epithermal gold deposit hosted in Paleozoic subaerial volcanic rocks in the western Tianshan orogenic belt, Xinjiang, China. The resource is more than 50 t gold at an average grade of > 4.4 ppm. The deposit occurs in the Tulasu volcanic fault-basin in the Paleozoic active continental margin on the northern side of the Yili-Central Tianshan plate. The host rocks are andesitic volcaniclastic rocks of the Paleozoic Dahalajunshan Formation, and the orebodies occur as veins in annular faults of a paleocaldera. Mineralization at Axi can be subdivided into five stages: quartz and/or chalcedony vein, quartz vein, quartz-carbonate vein, sulfide vein and carbonate vein. There are two types of ore host: quartz vein and altered rocks. Ore minerals are native gold, electrum, pyrite, marcasite, arsenopyrite, hematite, limonite, and trace amounts of pyrargyrite, polybasite, naumannite, cerargyrite, sphalerite, chalcopyrite, tetrahedrite, galena, pyrrhotite and clausthalite; gangue minerals are mainly quartz, chalcedony, illite, calcite, siderite, dolomite, adularia and laumontite. The main wall-rock alteration is silicification and phyllic alteration, carbonatization and propylitization. The deposit is characterized by an enrichment, relative to crustal abundance, of Au, Ag, As, Sb, Bi, Hg, Se, Te and Mo, depletion in base metals (Cu, Pb, and Zn), and a low Ag/Au ratio (0.5–3.7). Three types of fluid inclusions were recognized in quartz from the major mineralization stages: liquid aqueous inclusions, liquid-rich two-phase inclusions and small amounts of vapor-rich two-phase inclusions. Microthermometric measurements indicate that the final ice melting temperatures are − 0.3 to − 4.4 °C, corresponding to salinities of 0.5–6.9 wt.% NaCl equiv. (2.2 wt.% NaCl equiv. in average). The peak temperatures of ice melting varies from − 0.4 to − 1.9 °C, corresponding to salinities of 0.7–3.1 wt.% NaCl equiv. Homogenization temperatures range mainly between 120 and 240 °C, with an average of 190 °C and a maximum of 335 °C. The fluid density is 0.73 to 0.95 g/cm 3 and thus the estimated maximum mineralization depth is about 700 m. Hydrogen and oxygen isotopic compositions of the ore fluids lie within a narrow range: δD H2O is − 98 to − 116‰ and δ 18O H2O − 1.8 to 0.4‰. 3He/ 4He ranges from 0.0218 to 0.138 Ra, with an average of 0.044 Ra, indicating that He derived predominantly from crust with negligible mantle He in the ore fluids. By contrast, the 40Ar/ 36Ar ranges from 317.7 to 866.0, suggesting that crust-derived radioactive 40Ar⁎ accounts for 7.0 to 66%, and atmospheric 40Ar about 43 to 93% in the ore fluids. Hydrogen, oxygen, carbon, sulfur and noble gas isotopes indicate that the ore-forming fluids of the Axi gold deposit consisted predominantly of circulating meteoric water. Ore-forming metals may have derived mainly from the host volcaniclastic rocks of the Dahalajunshan Formation and basement rocks. The occurrence of adularia, platy calcite, and quartz or sulfide aggregates as pseudomorphs after bladed calcite in ore veins, and occurrence of aqueous liquid, and liquid-rich and vapor-rich two-phase inclusions, indicates that boiling of the ore-forming fluid have occurred, leading to supersaturation of the hydrothermal solution and deposition of ore metals. This is the main mineralization mechanism for quartz-vein type ores in Axi. The ore-forming fluid was buffered to a near-neutral pH in a reduced environment during mineralization. The preservation of this Paleozoic Axi deposit and its discovery required a rapid accumulation of sediments in the basin after formation of the deposit, and minimal amount of erosion after Late Cenozoic uplift.

Copper mineralization around the Ahar batholith, north of Ahar (NW Iran): Evidence for fluid evolution and the origin of the skarn ore deposit

This investigation presents and interprets fluid inclusion data from different lithological units of the Cu skarn deposits at Mazraeh, north of Ahar, Azarbaijan, NW Iran. The results provide an assessment of the P– T conditions and mineral–fluid evolution and suggest new exploration parameters. Five types of inclusions are recognized from quartz and garnet. The temperature of homogenization of Type I inclusions with daughter minerals halite and sylvite ranges from 312° to 470 °C with total salinity of 52 to 63 wt.% NaCl equiv.; Type II and III inclusions with halite have homogenization temperatures of 230° to 520 °C and salinity of 31 to 50 wt.% NaCl equiv. The salinity of Types IV and V biphase (liquid + vapor) inclusions, based on their final ice melting temperature, varies between 10.2 to 20.8 wt.% NaCl equiv. T h vs. salinity plots of inclusions show that the salinity of the fluids correlates positively with temperature. The inclusions formed at low pressure. Changes in the temperature and salinity of the fluids can be reconstructed from the inclusions. Highly saline, high-temperature fluids were most abundant during the main chalcopyrite ore-forming phase in the skarn and mineralized quartz veins. Low-salinity aqueous fluids were abundant in barren veins, in which there is no evidence for early hot high-salinity brine, and might have resulted from late-stage dilution and mixing of hydrothermal fluids with meteoric water. Based on petrographic features and fluid-inclusion data, early-stage magnetite deposition is related to boiling of fluid at temperatures of about 500 °C. At a later stage, boiling at temperatures of around 320° to 400 °C favored the deposition of sulfides and Fe mobility was decreased at these lower temperatures. The following inclusion characteristics may be used as exploration parameters in the Mazraeh area. (i) Presence of high-temperature, salt-bearing inclusions, with T h between 300 and 500 °C; (ii) High-salinity fluid inclusions; and (iii) Inclusions showing evidence of boiling of the fluid. In addition, the presence of magnetite is an important exploration parameter.

Experimental Determination of the NH4NO3/(NH4)2SO4/H2O Phase Diagram

We have studied the thermodynamic properties of the ammonium nitrate/ammonium sulfate/water system using differential scanning calorimetry and infrared spectroscopy of thin films at low temperatures. This is the first study focused on low temperatures, as previous experimental work on this system has been at 273 K and above. We have combined our experimental results with melting point data from the literature at high temperatures to create a solid/liquid phase diagram of the ammonium nitrate/ammonium sulfate/water system for temperatures below 343 K. Using phase diagram theory and Alkemade lines, we predict which solids are stable at equilibrium for all concentrations within the studied region. We also observed the decomposition of a solid at low temperatures which has not previously been reported. Finally, we have compared our predicted solids and final melting temperatures to the Aerosol Inorganics Model (AIM).

Effect of bar sealing parameters on OPP/MCPP heat seal strength

The effect of bar sealing parameters on the heat seal strength of oriented polypropylene (OPP)/metallic cast polypropylene (MCPP) laminate film was investigated. Based on the results obtained from the parametric study, a bar seal- ing process window was developed. All points drop within the process window are combinations of platen temperature and dwell time that produce acceptable heat seal. Optimum combinations are indicated by the lower border of the window. The plateau initiation temperature, Tpi of OPP/MCPP laminate film used in the present study occurred before the final melting temperature, Tmf of the sealant material. The highest achievable heat seal strength was at the plateau region, and the corre- sponding failure modes were delaminating, tearing or combine failure modes (delaminating and tearing). Minimum pres- sure level of 1.25 bars is necessary to bring the laminate interface into intimate contact in order to effect sealing.

The Linear Relationship Between the Proportion of Fresh Grass in the Cow Diet, Milk Fatty Acid Composition, and Butter Properties

Fresh grass in the cow diet improves the rheological and nutritional properties of butter. However, the relationship between the proportion of fresh grass in the diet and these properties is still unknown. The objective of the study was to determine the relationship between the proportion of fresh grass in the diet and the properties of milk and butter. Four groups of 2 cows were fed 4 isoenergetic diets characterized by increasing amounts of fresh grass (0, 30, 60, and 100% dry matter of forage) according to a Youden square design. Energy levels were similar among all diets. Thus, no effect of mobilization was observed and the results were only due to the proportion of fresh grass in the diet. Milk yield linearly increased with the proportion of fresh grass in the diet (+0.21kg/d per 10% of grass). Fat yield remained unchanged. Thus, by effect of dilution, increasing the proportion of fresh grass in the diet induced a linear decrease in fat content. Milk fat globule size decreased by 0.29μm when the proportion of grass reached 30% in the diet. Increasing the proportion of fresh grass in the diet induced a linear increase in unsaturated fatty acids percentages at the expense of saturated fatty acids. Relationships were +0.38, +0.12, +0.05 and −0.69 points/10% of fresh grass in the diet for C18:1 trans-11, C18:2 cis-9,trans-11, C18:3n-3, and C16:0, respectively. These modifications in fatty acid composition, and in particular in the spreadability index, C16:0/C18:1, were responsible for linear decreases in final melting temperature and solid fat content in butter fat, perceived in sensory analysis by a linear decrease in firmness in mouth. The nutritional value of butter was also linearly improved by the proportion of fresh grass in the diet by halving the atherogenicity index.

Nature of fluids and regional implications for Lesser Himalayan carbonates and associated mineralization

Fluid inclusion data are presented for the successive stages of limestone, dolomite, magnesite and sulphide-bearing quartz veins in Proterozoic carbonate rocks of the Lesser Himalaya. Subsurface fluids were H 2O–NaCl–KCl ± MgCl 2 ± CaCl 2 and showed successive increase in salinity and temperature. The salinity of the pore fluid during limestone diagenesis was in the range of ∼7.5–15 eq wt.% NaCl and the magnesite-forming fluids had a salinity of about 9 to 19 eq wt.% NaCl. This progressive rise in salinity is attributed to a more saline fluid in the deeper zones. The inverse relation between homogenization temperatures and final melting temperatures suggests mixing of the fluids during diagenesis, and highly depleted δ 18O values rule out participation of magmatic fluid in the mixing. A late stage carbonic fluid is linked with talc formation. The low temperature of sulphide-forming epigenetic solutions, as obtained from fluid inclusions, is also substantiated by the chemical data from these sulphides. δ 34S values in galena infer that magmatic sulphur was probably not involved, and the sulphur of the galena is derived from an isotopically heavy source.

Crystallization of polyamide confined in sub‐micrometer droplets dispersed in a molten polyethylene matrix

AbstractThe crystallization of submicrometer PA6 droplets dispersed in an ethylene‐1‐octene copolymer matrix, using PE‐g‐MA as a compatibilizer agent, is investigated. This system shows a nonconventional mechanical behavior at high temperatures. Up to ∼100 °C above the final melting temperature of the ethylene‐1‐octene copolymer matrix, the system shows good thermal and mechanical properties including dimensional stability. Because of the dispersed phase morphology of the system, so‐called fractionated/homogeneous crystallization takes place leading to an extra supercooling of PA6: ∼50 °C compared to the bulk PA6 crystallization temperature. Thus—though this is most probably just of interest for small‐scale research—the system can be processed at lowered temperatures while still providing exceptional high‐temperature properties. While the matrix is in the melt state when crystallization of the dispersed PA6 phase occurs, the possibility of matrix induced crystallization is absent, contrary to almost all of the ‘dispersed droplets in a matrix’ systems reported so far. The kinetics of this phenomenon is investigated in detail by DSC: the existence of fractionated/homogeneous crystallization is shown to be related to the lack of active nuclei in the dispersed droplets by means of self‐seeding experiments. The occurrence of extensive cold crystallization of PA6 in the confined environment is studied as is the crystallization kinetics, including the characterization of its time dependences showing its sporadic nature. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 815–825, 2006

Transport and phase dynamics of poly(vinyl pyrrolidone) doped plastically crystalline N-methyl- N-propylpyrrolidinium tetrafluoroborate

The plastic crystal phase forming N-methyl- N-propylpyrrolidinium tetrafluoroborate organic salt (P 13BF 4) was combined with 2, 5 and 10 wt.% poly(vinyl pyrrolidone) (PVP). The ternary 2 wt.% PVP/2 wt.% LiBF 4/P 13BF 4 was also investigated. Thermal analysis, conductivity, optical thermomicroscopy, and Nuclear Magnetic Resonance ( 11B, 19F, 1H, 7Li) were used to probe the fundamental transport processes. Both the onset of phase I and the final melting temperature were reduced with increasing additions of PVP. Conductivity in phase I was 2.6 × 10 − 4 S cm − 1 5.2 × 10 − 4 S cm − 1 1.1 × 10 − 4 S cm − 1 and 3.9 × 10 − 5 S cm − 1 for 0, 2, 5 and 10 wt.%PVP/P 13BF 4, respectively. Doping with 2 wt.% LiBF 4 increased the conductivity by up to an order of magnitude in phase II. Further additions of 2 wt.% PVP slightly reduced the conductivity, although it remained higher than for pure P 13BF 4.

Crystallisation and melting properties of dromedary milk fat globules studied by X‐ray diffraction and differential scanning calorimetry. Comparison with anhydrous dromedary milk fat

AbstractCrystallisation and melting properties of triacylglycerols (TG) in dromedary milk fat (DMF) globules are studied by X‐ray diffraction (XRD) as a function of temperature coupled with high‐sensitivity differential scanning calorimetry (DSC), using synchrotron radiation. The crystallisation properties studied on cooling at ∣dT/dt∣ = 1 °C.min−1 from 60 °C to −8 °C show the successive formation of two double‐chain length (2L) lamellar structures: α 2L1 (46.7 Å) from 22 °C and β' 2L2 (41.7 Å) from 9 °C, which coexist until the end of the cooling process. These two types of crystals are related to the two exothermal peaks recorded simultaneously by DSC. The melting properties are studied on subsequent heating of DMF globules at dT/dt = 1 °C.min−1. The detailed analysis of the intensity and position of the XRD peaks recorded as a function of time shows that (i) the α 2L1 structure melts first, (ii) some TG from 2L1 melt and are incorporated again in the 2L2 structure, and (iii) the 2L2 structure melts with a final melting temperature over 44 °C. The influence of the dispersion of TG molecules in individual fat globules, with the presence of an interface with water, was determined by comparing their crystallisation behaviour to that of the same TG extracted from cream (anhydrous DMF) under the same experimental conditions. Results show that the same lamellar structures, α 2L1 and then β' 2L2, are formed on cooling in the dispersed and bulk states. However, crystallisation in the unstable α form is favoured in fat globules.