scholarly journals Tourmalinisation in peraluminous granitic context : from experiment to thermodynamic modelling

2021 ◽  
Author(s):  
Julien Fort ◽  
Stanislas Sizaret ◽  
Michel Pichavant ◽  
Arnault Lassin ◽  
Johann Tuduri ◽  
...  
Keyword(s):  
Solid Solution ◽  
Thermodynamic Properties ◽  
Stability Field ◽  
Peraluminous Granite ◽  
Physico Chemical ◽  
Fe Content ◽  
Chemical Conditions ◽  
Using Data ◽  
The Stability

<p>Tourmaline records the physico chemical conditions during its cristallisation, as its primary chemical zonations are generally unbalanced, its occurrence as alteration product could be used to decipher the physicochemical properties of mineralizing fluids. However, the role of the tourmalinisation in hydrothermal processes remains little studied, if not poorly understood.  The complexity of its thermodynamic properties is related to the presence of four cationic sites allowing the accommodation of a wide variety of elements (Henry and Dutrow, 2018). Moreover the phenomena of deprotonation, Si-<sup>IV</sup>B and valence state, make the approach of solid solution properties complex (Hughes et al., 2001; Henry et al., 2011; Bačík, 2015; Morgan, 2016). Thus, thermodynamic properties are most often estimated  (Garofalo et al., 2000; Hinsberg and Schumacher, 2007) and only a few measurements could be carried out on a reduced number of near-endmembers crystals (Kuyunko et al., 1984; Ogorodova et al., 2012).</p><p>This study aims to investigate experimentally the stability field of schorl (Na-Fe) – dravite (Na-Mg) solid solution at 2 kbar total pressure between 400° and 600°C as a function of the boron content of the fluid and fO2 condition, using an internally heated gas apparatus. Those metasomatic experiments have been conducted on a mixture of naturals crystals of cordierite + albite, representing a peraluminous granite composition in a Na-Mg-Fe-Al-Si-B-O-H system, characterized by a high-Mg, low-Fe content. These experiments were performed in order to simulate a classic aluminous host of these tourmaline alterations in granitic context. The results will be studied, in terms of stability of the tourmaline species, chemistry variation and texture. They will be compared with thermodynamic models build using data from the literature (Korges et al., 2018; Pan et al., 2019 among others) . Ultimately, the objective is to characterize in a P, T, W/R space, the chemical evolution of fluids, the alteration sequence of rocks and the variations in volumes related to the successive reactions.</p>

scholarly journals The Role of Employment Protection during an Exogenous Shock to an Economy

2011 ◽  
Vol 11 (2) ◽  
pp. 1850225 ◽  
Author(s):  
Miki Malul ◽  
Mosi Rosenboim ◽  
Tal Shavit ◽  
Shlomo Yedidia Tarba
Keyword(s):  
Economic Crisis ◽  
Employment Protection ◽  
Exogenous Shock ◽  
Unemployment Rates ◽  
World Crisis ◽  
Automatic Stabilizer ◽  
Medium Level ◽  
Using Data ◽  
The Stability

This paper explores the role of employment protection when powerful external crises reduce demand for products. We first present a theoretical framework that shows that employment protection has a U-shaped effect on abnormal unemployment during a negative exogenous shock to an economy. Using data from the 33 OECD countries, we analyze how the level of employment protection affected the stability of unemployment rates during the recent global economic crisis. The results suggest that countries with an intermediate level of employment protection will have more stable unemployment rates during a world crisis. The policy implication of our paper is that countries should seek a medium level of employment protection that may act as an automatic stabilizer of the economy on the macro level.

Ethanol stability of casein micelles – a hypothesis concerning the role of calcium phosphate

1987 ◽  
Vol 54 (3) ◽  
pp. 389-395 ◽  
Author(s):  
David S. Horne
Keyword(s):  
Ionic Strength ◽  
Skim Milk ◽  
Buffer System ◽  
Casein Micelles ◽  
Buffer Solutions ◽  
Relative Response ◽  
Using Data ◽  
The Stability ◽  
Ethanol Stability

SummaryThe ethanol (EtOH) stability of skim milk and the stability towards aggregation of casein micelles diluted into ethanolic buffer solutions were compared using data obtained from previously published experiments. Differences in absolute stability and in relative response were observed when Ca2+ level and pH were adjusted, the buffer system results lying below those from skim milk in both cases. Increasing the ionic strength of skim milk adjusted to pH 7·0 lowered its EtOH stability whereas increasing the ionic strength of the diluting buffer increased the stability of the casein micelles. The hypothesis is put forward that the differences are due to the simultaneous precipitation of Ca phosphate when EtOH is added to skim milk. This draws calcium from the caseinate sites of the micelle, counteracting the destabilizing effects of the EtOH towards the micelle. Such removal and the consequent restructuring are kinetically controlled and micellar precipitation in skim milk finally occurs when the micellar coagulation time falls within the time scale of the restructuring reactions.

An EXAFS study of cation site distortions through the P2/c-P1̄ phase transition in the synthetic cuproscheelite-sanmartinite solid solution

1994 ◽  
Vol 58 (391) ◽  
pp. 185-199 ◽  
Author(s):  
P. F. Schofield ◽  
J. M. Charnock ◽  
G. Cressey ◽  
C. M. B. Henderson
Keyword(s):  
Phase Transition ◽  
Solid Solution ◽  
Stability Field ◽  
Cation Site ◽  
Cu Content ◽  
Square Planar ◽  
Jahn Teller ◽  
Exafs Study ◽  
Four Square ◽  
The Stability

AbstractEXAFS spectroscopy has been used to monitor changes in divalent cation site geometries across the P2/c-P1̄ phase transition in the sanmartinite (ZnWO4)-cuproscheelite (CuWO4) solid solution at ambient and liquid nitrogen temperatures. In the ZnWO4 end member, Zn occupies axially-compressed ZnO6 octahedra with two axial Zn-O bonds at approximately 1.95 Å and four square planar Zn-O bonds at approximately 2.11 Å. The substitution of Zn by Cu generates a second Zn environment with four short square planar Zn-O bonds and two longer axial Zn-O bonds. The proportion of the latter site increases progressively as the Cu content increases. Cu EXAFS reveals that the CuO6 octahedra maintain their Jahn-Teller axially-elongate geometry throughout the majority of the solid solution and only occur as axially-compressed octahedra well within the stability field of the Zn-rich phase with monoclinic long-range order.

Probiotics in colorectal cancer (CRC) with emphasis on mechanisms of action and current perspectives

2013 ◽  
Vol 62 (8) ◽  
pp. 1107-1123 ◽  
Author(s):  
Imen Kahouli ◽  
Catherine Tomaro-Duchesneau ◽  
Satya Prakash
Keyword(s):  
Colorectal Cancer ◽  
Early Stage ◽  
Tumour Progression ◽  
Great Promise ◽  
Anticancer Compounds ◽  
Beneficial Effects ◽  
Physico Chemical ◽  
Recent Developments ◽  
Chemical Conditions

Colorectal cancer (CRC) is the third most common form of cancer. Diverse therapies such as chemotherapy, immunotherapy and radiation have shown beneficial effects, but are limited because of their safety and toxicity. Probiotic formulations have shown great promise in CRC as preventive and early stage therapeutics. This review highlights the importance of a balanced intestinal microbiota and summarizes the recent developments in probiotics for treating CRC. Specifically, this report describes evidence of the role of probiotics in modulating the microbiota, in improving the physico-chemical conditions of the gut and in reducing oxidative stress. It also discusses the mechanisms of probiotics in inhibiting tumour progression, in producing anticancer compounds and in modulating the host immune response. Even though some of these effects were observed in several clinical trials, when probiotic formulations were used as a supplement to CRC therapies, the application of probiotics as biotherapeutics against CRC still needs further investigation.

Diffuse scattering in protein crystallography

1995 ◽  
Vol 28 (2) ◽  
pp. 131-169 ◽  
Author(s):  
Jean-Pierre Benoit ◽  
Jean Doucet
Keyword(s):  
Molecular Biology ◽  
Active Site ◽  
Diffuse Scattering ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physico Chemical ◽  
Chemical Conditions ◽  
Functional Mechanisms

The understanding of flexibility and deformability in proteins is one of the current major challenges of structural molecular biology. The knowledge of the average atomic positions of three-dimensional folding of proteins, which is obtained either by X-ray diffraction or n.m.r. spectroscopy, is generally not sufficient to explain their functional mechanisms. Very often it is necessary to consider the existence of other concerted atomic motions as, for example, in the well-known case of the CO molecule fixation at the active site of myoglobin which requires the concerted displacement of a large number of atoms in order to open a channel down to this site. This opening, which depends on the physico-chemical conditions, plays the role of a regulator in the biochemical reactions (Janin & Wodak, 1983; Tainer et al. 1984; Westhof et al. 1984; Ormos et al. 1988).

Trophic structure within the Bristol Channel: seasonality and stability in Bridgwater Bay

1992 ◽  
Vol 72 (3) ◽  
pp. 675-690 ◽  
Author(s):  
P. A. Henderson ◽  
D. James ◽  
R. H. A. Holmes
Keyword(s):  
Trophic Structure ◽  
General Description ◽  
Dominant Animal ◽  
Estuarine Site ◽  
Overall Stability ◽  
Average Biomass ◽  
Using Data ◽  
The Stability ◽  
Stability And Resilience

A general description of the trophic inter-relationships and the food web within Bridgwater Bay, Somerset, England, is presented. This Bay is a lower estuarine site within the Bristol Channel. Particular attention is given to the use of the area by fish and larger crustaceans which are the dominant animal groups. Using data collected over a ten-year period of monthly sampling, the relative average biomass of all fish and larger crustaceans found within the Bay is calculated for each month of the year. These averages are used to produce food webs which also show species relative abundance for each calendar month.It is shown that the trophic structure follows a seasonal cycle due to migration. The application of the concept of stability within such a dynamic system is discussed. The role of compartmentalization of the ecosystem into a number of loosely connected groups as an aid to overall stability is discussed. While there is no evidence that contemporaneous compartments exist, it is argued that inter-specific interactions are temporally limited because of the different periods of annual residence of the species. It is suggested that the stability and resilience to interference shown by these estuarine systems is enhanced by temporal partitions.

scholarly journals Tourmaline Composition of the Kışladağ Porphyry Au Deposit, Western Turkey: Implication of Epithermal Overprint

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 789
Author(s):  
Ömer Bozkaya ◽  
Ivan A. Baksheev ◽  
Nurullah Hanilçi ◽  
Gülcan Bozkaya ◽  
Vsevolod Y. Prokofiev ◽  
...  
Keyword(s):  
Hydrothermal Process ◽  
Western Turkey ◽  
Magmatic Complex ◽  
Fine Aggregates ◽  
Physico Chemical ◽  
Fe Content ◽  
Argillic Alteration ◽  
Intrusive Rocks ◽  
Chemical Conditions ◽  
Site Vacancy

The Kışladağ porphyry Au deposit occurs in a middle Miocene magmatic complex comprising three different intrusions and magmatic-hydrothermal brecciation related to the multiphase effects of the different intrusions. Tourmaline occurrences are common throughout the deposit, mostly as an outer alteration rim around the veins with lesser amounts disseminated in the intrusions, and are associated with every phase of mineralization. Tourmaline mineralization has developed as a tourmaline-rich matrix in brecciated zones and tourmaline-quartz and/or tourmaline-sulfide veinlets within the different intrusive rocks. Tourmaline was identified in the tourmaline-bearing breccia zone (TBZ) and intrusive rocks that had undergone potassic, phyllic, and advanced argillic alteration. The tourmaline is present as two morphological varieties, aggregates of fine crystals (rosettes, fan-shaped) and larger isolated crystals and their aggregates. Four tourmaline generations (tourmaline I to IV) have different compositions and substitutions. Tourmaline I in TBZ and INT#1 is distinguished by the highest Fetot and enriched in Fe3+. Tourmalines II and III occur as fine aggregates, accompanied by the formation of isolated crystals and are characterized by lower Fetot and Fe3+. Tourmaline IV is characterized by the lowest Fetot, enriched in Cl, and has the highest proportion of X-site vacancy among all the tourmalines. Tourmaline I may be attributed to the potassic stage in INT#1 and early tourmaline in TBZ. Tourmalines II and III from INT#1 and the TBZ could be referred to the phyllic stage. The low Fe content in tourmaline is caused by the simultaneous deposition of sulfide minerals. Tourmaline IV from the TBZ and tourmaline II from INT#3 are distinguished by the high X-site vacancy proportion up to the formation of X-site vacant species as well as enriched in Cl; they can be attributed to the argillic stage of the hydrothermal process. The textural and especially chemical data of the tourmaline from the Kışladağ Au deposit provide information on the physico-chemical conditions during the porphyry to epithermal transition and subsequent epithermal overprinting.

Olivenite-Adamite Solid Solution From Oxidation Zone in Rędziny (West Sudetes, Poland)

Mineralogia ◽  
2006 ◽  
Vol 37 (2) ◽  
pp. 101-110 ◽  
Author(s):  
Boźena Gołębiowska ◽  
Adam Pieczka ◽  
Wojciech Franus
Keyword(s):  
Solid Solution ◽  
Carbonate Rocks ◽  
Oxidation Zone ◽  
Stability Field ◽  
Mineral Phases ◽  
West Sudetes ◽  
Polymetallic Mineralization ◽  
The Stability ◽  
Weathering Zone ◽  
Ubiquitous Presence

Olivenite-Adamite Solid Solution From Oxidation Zone in Rędziny (West Sudetes, Poland)An extensive hydrothermal polymetallic mineralization with a well developed oxidation zone rich in secondary minerals occurs in dolostones several hundred meters from the Karkonosze granite at Rędziny. Using XRD and FTIR methods, mineral phases representing transitional members of the olivenite-adamite solid solution have been identified. Electron microprobe analyses reveal the most common varieties to be zincian olivenite and cuprous adamite with compositions ranging from (Cu1.17Zn0.83)(AsO4)(OH) to (Zn1.38Cu0.62)(AsO4)(OH). The two minerals are subordinate in the weathering zone which can be characterized as having been a zone of low Cu2+and Zn2+activity and with mineralizing solutions of increased pH. A high Ca2+concentration due to the ubiquitous presence of carbonate rocks resulted in the expansion of the stability field of another arsenate, conichalcite (or Zn-bearing conichalcite), which is a common mineral there.

scholarly journals Hydrothermal Sphalerites from Ore Deposits of Baia Mare Area

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1323
Author(s):  
Gheorghe Damian ◽  
Andrei Buzatu ◽  
Andrei Ionuţ Apopei ◽  
Floarea Damian ◽  
Andreea Elena Maftei
Keyword(s):  
Manganese Content ◽  
Ore Deposits ◽  
Main Element ◽  
Cadmium Content ◽  
Important Indicator ◽  
Physico Chemical ◽  
Fe Content ◽  
Baia Mare ◽  
Iron And Zinc ◽  
Chemical Conditions

Sphalerite is an abundant mineral in the hydrothermal deposits from the Baia Mare and Oaș areas (northwestern Romania). Sphalerite samples were analyzed with an electron probe microanalyzer and Raman spectroscopy. The obtained results indicated different amounts of Fe in the various deposits from the Baia Mare and Oaș areas. The sphalerites from Baia Sprie, Cavnic, Iba, Turț Penigher, and Breiner have a low Fe wt.% content. High Fe wt.% contents are at Herja and partly at Ghezuri and Nistru (copper stage) where sphalerite is associated with pyrrhotite. The correlation between iron and zinc from sphalerites is strongly negative. The negative correlation shows that iron is the main element that replaces zinc in the sphalerite structure. The manganese content of sphalerites in the Baia Mare and Oaș area is up to 0.84 wt.%. The cadmium content is quite uniform in the Baia Mare and Oaș area with contents ranging from 0.01 to 0.72 wt.%. The Fe content of sphalerites is an important indicator of the physico-chemical conditions of deposit formation because it is a function of temperature, pressure, and sulfur fugacity.

scholarly journals PERAN BAITUL MAAL WAT TAMWIL (BMT) AMANAH UMMAH TERHADAP PENINGKATAN USAHA PEDAGANG KECIL DI PASAR KARAH SURABAYA

2019 ◽  
Vol 5 (2) ◽  
pp. 93
Author(s):  
Puspa Indraswari ◽  
Qudsi Fauzi
Keyword(s):  
Data Collection ◽  
Research Methods ◽  
Direct Observation ◽  
Qualitative Method ◽  
Business Income ◽  
Using Data ◽  
The Stability ◽  
Small Traders

This study aims to analyze the role of BMT “Amanah Ummah” in empower the small traders. The research methods used in this research was case study qualitative method, using data collection techniques performed with conductive interviews and direct observation with the object of research. The result of this study indicate that BMT has been instrumental in increasing the business of small traders in Karah market. The business improvement from the small traders can be seen from the business turnover, business asset, business income and the stability of their business. The member of BMT in Karah market, on average has increased their business seen from their business volume, increasing of daily inventory such asequipment used for trade and revenues of their business income.

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