Understanding basaltic Plinian activity at Masaya caldera, Nicaragua

2020 ◽  
Author(s):  
Emily C Bamber ◽  
Fabio Arzilli ◽  
Margherita Polacci ◽  
Giuseppe La Spina ◽  
Maurizio Petrelli ◽  
...  
Keyword(s):  
Basaltic Magma ◽  
Magma Ascent ◽  
Volcanic Complex ◽  
Volatile Elements ◽  
Plinian Eruptions ◽  
Effusive Activity ◽  
Low Viscosity ◽  
Physico Chemical ◽  
Significant Difference ◽  
Basaltic Plinian Eruption

<p>Plinian eruptions are the most hazardous yet enigmatic style of volcanism at basaltic systems. The low viscosity of basaltic magma should preclude its fragmentation; however, there are several recognised examples of basaltic Plinian activity. Historical eruptions of Masaya caldera, Nicaragua; Etna, Italy (122 BC); and Tarawera, New Zealand (1886) have ejected > 1 km<sup>3</sup> of material. The Las Sierras-Masaya volcanic complex (Masaya caldera) has produced several basaltic Plinian eruptions, yet currently exhibits low explosive-effusive activity. This volcano has erupted chemically homogeneous magmas over at least the past 6000 years, which suggests that this significant difference in eruptive style is not attributable to a compositional change. Therefore, the cause of increased explosivity at Masaya caldera remains uncertain. </p><p>We present new measurements of major, trace and volatile elements in basaltic Plinian eruption products from the Fontana Lapilli (60 ka) and Masaya Triple Layer (2.1 ka) eruptions of the Las Sierras- Masaya volcanic complex. We use our data in rheological and thermometric models to define the pre- and syn-eruptive conditions that favour highly explosive activity. We then combine our petrological data with a numerical conduit model to constrain the pre-eruptive condition of the magma reservoir and simulate the conduit processes, to understand the magmatic conditions that promote fragmentation during magma ascent. The common physico-chemical magmatic conditions that promote basaltic Plinian activity at Masaya are high microlite crystallinity, moderate storage temperatures and a low initial H<sub>2</sub>O concentration. Our combined approach greatly improves our general understanding of explosive basaltic activity and provides new insight into the effusive-explosive transition of the highly hazardous Las Sierras-Masaya system.</p>

Antibiotic Distribution in a Bone Cement Spacer Model

2007 ◽  
Vol 17 (4) ◽  
pp. 218-223 ◽  
Author(s):  
K. Shiramizu ◽  
V. Lovric ◽  
A.M.D. Leung ◽  
W.R. Walsh
Keyword(s):  
Liquid Phase ◽  
Bone Cement ◽  
Cross Sections ◽  
High Dose ◽  
Cement Spacer ◽  
Traditional Technique ◽  
Low Viscosity ◽  
Significant Difference ◽  
Group A ◽  
Medium Viscosity

Purpose To mix high dose antibiotic powder to the bone cement more easily, Hanssen et al reported mixing the antibiotics with the cement during its liquid phase but made no comments about the relevance of cement viscosity and antibiotic distribution. The purpose of this study was to investigate the effect of the cement mixing technique and cement viscosity on the antibiotics distribution in a cement spacer model. Methods Thirty cylindrical models from three groups were examined. Group A was made by mixing the antibiotics with medium viscosity cement prior to adding the liquid monomer (traditional technique). Group B was made by mixing the antibiotics with medium viscosity cement during its liquid phase (Hanssen's technique). Group C was made by traditional technique with low viscosity cement. In all groups 2 g of tetracycline was used. Three 0.1 mm thick cross sections from each spacer model were examined under the fluorescent microscope. The fluorescent spots of tetracycline were calculated automatically in pixels. To evaluate the distribution of the antibiotics in the spacer model, we selected the cross section with the highest number of pixels and the one with the lowest number of pixels from each of the three cross sections and calculated the difference between them. The distribution disequilibrium was compared between group A and B, A and C. Results No significant difference was observed in either comparison. Conclusion The Hanssen's mixing technique can be used when using high dose antibiotics, and either medium or low viscosity cement could be used in terms of antibiotic distribution.

Impact of Resin Composite Viscosity and Fill-technique on Internal Gap in Class I Restorations: An OCT Evaluation

2021 ◽  
Author(s):  
KR Kantovitz ◽  
LL Cabral ◽  
NR Carlos ◽  
AZ de Freitas ◽  
DC Peruzzo ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Resin Composite ◽  
Oral Care ◽  
High Viscosity ◽  
Class I ◽  
Low Viscosity ◽  
Significant Difference ◽  
Before And After ◽  
Internal Adaptation ◽  
Internal Gap

SUMMARY The aim of this in vitro study was to quantitatively evaluate the internal gap of resin composites of high-and low-viscosity used in single- and incremental-fill techniques in Class I cavities exposed to thermal cycling (TC) using optical coherence tomography (OCT). Cavities of 4-mm depth and 3-mm diameter were prepared in 36 third molars randomly distributed into four groups, according to viscosity of restorative resin-based composite (high or low viscosity, all from 3M Oral Care) and technique application (bulk or incremental fill) used (n=9): RC, high-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Universal Restorative); BF, high-viscosity, bulk-fill, resin-based composite (Filtek One Bulk Fill); LRC, low-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Flowable Universal Restorative); and LBF, low-viscosity, bulk-fill, resin-based composite (Filtek Flowable Restorative). Single Bond Universal Adhesive system (3M Oral Care) was used in all the experimental groups. The incremental-fill technique was used for RC and LRC groups (2-mm increments), and a single-layer technique was used for BF and LBF groups, as recommended by the manufacturer. The internal adaptation of the resin at all dentin walls was evaluated before and after TC (5000 cycles between 5°C and 55°C) using OCT images. Five images of each restored tooth were obtained. Images were analyzed using ImageJ software that measured the entire length of the gaps at the dentin–restoration interface. The length of gaps (μm) was analyzed using two-way repeated measures ANOVA and the Tukey tests (α=0.05). There was a significant interaction between material types and TC (p=0.006), and a significant difference among all material types (p<0.0001), before and after TC (p<0.0001). Increased internal gaps at the dentin–restoration interface were noticed after TC for all groups. RC presented the lowest value of internal gap before and after TC, while LBF showed the highest values of internal gap after TC. In conclusion, TC negatively affected the integrity of internal gap, whereas high-viscosity, incremental-fill, resin-based composite presented better performance in terms of internal adaptation than low-viscosity, bulk-fill materials in Class I cavities.

scholarly journals Physico-chemical properties, probiotic stability and sensory characteristics of Lactobacillus plantarum S20 – supplemented passion fruit (Passiflora edulis f. flavicarpa Deg.) juice powder

Food Research ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 320-326
Author(s):  
Reifrey, A. Lascano ◽  
M.G.L.D. Gan ◽  
A.S.L. Sulabo ◽  
D.M.O. Santiago ◽  
L.B. Ancheta ◽  
...  
Keyword(s):  
Moisture Content ◽  
Lactobacillus Plantarum ◽  
Spray Drying ◽  
Fruit Juice ◽  
Chemical Properties ◽  
Passion Fruit ◽  
Soluble Solids ◽  
Passiflora Edulis ◽  
Physico Chemical ◽  
Significant Difference

The study aimed to develop a non-dairy-based probiotic-supplemented product using an underutilized crop in the Philippines such as the yellow passion fruit (Passiflora edulis f. flavicarpa Deg.). The physico-chemical properties (moisture content, water activity, pH, and total soluble solids), probiotics stability at different storage temperatures (4°C, 25°C, and 37°C), and the sensory characteristics of Lactobacillus plantarum S20-supplemented passion fruit juice powder was evaluated. Passion fruit juice powder and L. plantarum S20 were first prepared using low-temperature spray drying utilizing maltodextrin as a carrier, with yield as 42.97% and 21.17%, respectively. Spray drying of probiotics culture also resulted in 42.68% log survivability. The formulated juice powder had a final moisture content of 1.729±0.38% and water activity of 0.398±0.0051, and with recommended dilution with water, had a final pH and total soluble solids of 3.40±0.10 and 12.00±0.00° Brix, respectively. Results also showed that storage of the formulated juice powder at 4°C yielded the highest probiotic stability, maintaining a viable log count of 4.27 per g, while storage at 37°C showed no microbial growth. Sensory evaluation of probioticsupplemented passion fruit juice against a non-probiotic-supplemented one revealed significant difference in terms of color, sweetness, and sourness, while no significant difference was observed in terms of aroma, mouthfeel, and general acceptability.

scholarly journals Effects of Fermented Maize Residue Addition on the Physico-chemical and Sensory Properties of Chin-Chin

2021 ◽  
pp. 65-73
Author(s):  
Owuno Friday ◽  
Achinewu Simeon Chituru
Keyword(s):  
Proximate Composition ◽  
Protein Digestibility ◽  
Pasting Properties ◽  
Absorption Capacity ◽  
Composite Flour ◽  
Crude Fibre ◽  
Overall Acceptability ◽  
Physico Chemical ◽  
Significant Difference ◽  
Pasting Temperature

Chin-Chin, a traditional Nigerian snack was prepared utilizing wheat-fermented maize residue composite flour at 0 – 30% replacement levels. Effects of this addition on the functional and pasting properties of the flour composite was evaluated. The snack produced was also evaluated for its sensory attributes, proximate composition and invitro-protein digestibility (IVPD). Functional properties results showed an increase in water absorption capacity (WAC), a decrease in oil absorption capacity (OAC), decrease in Bulk Density (BD), swelling power and solubility index with residue addition. Pasting property results showed a drop in the value of peak, trough, breakdown and final viscosity with substitution while set back viscosity increased.Peak temperature decreased, but values for pasting temperature showed no significant difference between the control and the blends. Results for sensory evaluation showed equal preference for overall acceptability. Proximate composition results showed residue addition led to an increase in crude fibre and protein content with a drop in the carbohydrate value. Residue addition did not increase protein digestibility. Addition of fermented maize residue in chin-chin production can be another way of utilizing the fibre rich by-product of the production of fermented maize starch.

scholarly journals Role of syn-eruptive plagioclase disequilibrium crystallization in basaltic magma ascent dynamics

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
G. La Spina ◽  
M. Burton ◽  
M. de’ Michieli Vitturi ◽  
F. Arzilli
Keyword(s):  
Basaltic Magma ◽  
Magma Ascent

scholarly journals Characterization of Two Chickpea Varieties and the Effect of Cooking on their Physico-chemical and Functional Properties of Flours

2016 ◽  
Vol 5 (5) ◽  
pp. 67
Author(s):  
Victoria G. Aguilar-Raymundo ◽  
Jorge F. Vélez-Ruíz
Keyword(s):  
Functional Properties ◽  
Wide Distribution ◽  
Pasting Properties ◽  
Absorption Capacity ◽  
Water Absorption Capacity ◽  
Moisture Contents ◽  
Physico Chemical ◽  
Significant Difference ◽  
Physicochemical And Functional Properties

Considering the nutritional and functional characteristics of chickpea, flours of two varieties of chickpea (“Blanco Noroeste” and “Costa 2004”) were prepared to know the effect of cooking. Thus the objective of this study was to compare their physicochemical and functional properties in both, raw and cooked flours. Physical properties of the grain, for the two varieties were similar, whereas the physicochemical and functional properties of the flours exhibited differences as a function of the variety and the processing. The chickpea cooked flours showed lower lightness and higher redness and yellowness with respect to raw flours. The proximal composition of cooked flours presented significant differences in fat (5.98% - 6.09%) and moisture contents (0.48% - 0.54%) with respect to raw flours. The particle size distribution determined for the raw and cooked flours samples, indicated a unimodal behavior with a wide distribution. The water absorption capacity and oil capacity showed significant difference among flour varieties. For pasting properties, a higher viscosity was measured for Costa 2004 (380 cP) and Blanco Noroeste (272 cP) raw flours, raw flour exhibited better pasting properties than cooked flours. 

scholarly journals The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs

2019 ◽  
Vol 490 (2) ◽  
pp. 2448-2457 ◽  
Author(s):  
I Ramírez ◽  
S Khanal ◽  
S J Lichon ◽  
J Chanamé ◽  
M Endl ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Binary Star ◽  
Elemental Abundance ◽  
Condensation Temperature ◽  
Volatile Elements ◽  
Significant Difference ◽  
Iron Abundance ◽  
Binary Star System ◽  
Projected Distance ◽  
Temperature Surface

ABSTRACT We conducted a high-precision elemental abundance analysis of the twin-star comoving pair HIP 34407/HIP 34426. With mean error of 0.013 dex in the differential abundances (Δ[X/H]), a significant difference was found: HIP 34407 is more metal rich than HIP 34426. The elemental abundance differences correlate strongly with condensation temperature, with the lowest for the volatile elements like carbon around 0.05 ± 0.02 dex, and the highest up to about 0.22 ± 0.01 dex for the most refractory elements like aluminium. Dissimilar chemical composition for stars in twin-star comoving pairs is not uncommon, thus we compile previously published results like ours and look for correlations between abundance differences and stellar parameters, finding no significant trends with average effective temperature, surface gravity, iron abundance, or their differences. Instead, we found a weak correlation between the absolute value of abundance difference and the projected distance between the stars in each pair that appears to be more important for elements that have a low absolute abundance. If confirmed, this correlation could be an important observational constraint for binary star system formation scenarios.

Post-fire carbon emissions from degraded tropical peat swamp forests in Brunei

2020 ◽  
Author(s):  
Massimo Lupascu ◽  
Hasan Akhtar ◽  
Thomas E.L. Smith ◽  
Rahayu S. Sukri
Keyword(s):  
Organic Carbon ◽  
Water Table ◽  
Ecosystem Respiration ◽  
Hot Spot ◽  
Tropical Peat ◽  
Brunei Darussalam ◽  
Peat Swamp ◽  
Physico Chemical ◽  
Significant Difference ◽  
Tropical Peat Swamp

<p>Tropical peat swamp forests hold about 15–19% of the global organic carbon (C) pool of which 77% is found in Southeast Asia. Nonetheless, these ecosystems have been drained, exploited for timber and land for agriculture, leading to frequent fires in the region. Fire alters the physico-chemical characteristics of peat as well as the hydrology, which may convert these ecosystems into a source of C for decades as C emissions to the atmosphere exceeds photosynthesis.</p><p>To understand the long-term impacts of fire on C cycling, we investigated C emissions in intact and degraded PSFs in Brunei Darussalam, which has experienced 7 fires over the last 40 years. We quantified the magnitude and patterns of C loss (CO<sub>2</sub>, CH<sub>4, </sub>and Dissolved Organic carbon) and soil-water quality characteristics along with continuous monitoring of soil temperature and water table level from June 2017 to January 2019. To investigate the age and sources of C contributing to ecosystem respiration (R<sub>eco</sub>) and CH<sub>4</sub>, we used natural tracers such as <sup>14</sup>C.</p><p>We observed a major difference in the physico-chemical parameters, which in turn affected C dynamics, especially CH<sub>4</sub>. In burnt areas (7.8±2.2 mg CH<sub>4 </sub>m<sup>-2</sup> hr<sup>-1</sup>) the CH<sub>4</sub> emission was approximately twice compared to the intact peat swamp forest (4.0±2.0 mg CH<sub>4 </sub>m<sup>-2</sup> hr<sup>-1</sup>) due to prolonged higher water table creating optimum methanogenesis conditions. On the contrary, R<sub>eco</sub> did not show a significant difference between burnt (432±83 mg CO<sub>2 </sub>m<sup>-2</sup> hr<sup>-1</sup>) and intact areas (359±76 mg CO<sub>2 </sub>m<sup>-2</sup> hr<sup>-1</sup>). Further, radiocarbon (<sup>14</sup>C) analysis showed an overall modern signature for both CO<sub>2 </sub>and CH<sub>4</sub> fluxes implying a microbial preference for the more labile C fraction in solution.</p><p>With frequent fires and more flooding in the future, these degraded tropical peat swamp forests areas may remain a hot spot of C emissions as suggested by our findings.</p>

Comparative Petrological Studies of 1962 and 1988–1989 Eruptions of Tokachidake Volcano, Japan: A Case Study for Understanding the Relationship Between Eruption Style and Magma Processes

2019 ◽  
Vol 14 (5) ◽  
pp. 766-779
Author(s):  
Mitsuhiro Nakagawa ◽  
Akiko Matsumoto ◽  
Kyohei Kobayashi ◽  
Keiji Wada ◽  
◽  
...  
Keyword(s):  
Basaltic Magma ◽  
Magma Ascent ◽  
Eruption Style ◽  
Magma Plumbing System ◽  
Magma Supply ◽  
The Matrix ◽  
Cap Rock ◽  
The Difference ◽  
The Relationship

Repeated magmatic eruptions of Tokachidake volcano have caused severe volcanic disasters on three occasions during the 20th century. To prepare for the next eruptive activity, understanding the structure of the magma plumbing system by using petrological analysis of juvenile materials is crucial. Here, we perform petrological analysis of juvenile materials to investigate the difference between two contrasting eruptions in 1962 and 1988–1989, respectively. All these juvenile materials are composed of mafic andesite, which were formed by mixing of olivine-bearing basaltic and pyroxene andesitic magmas. The compositional zonations of olivine phenocrysts in all of these rocks suggest that the injection of the basaltic magma into the andesitic magma occurred several months prior to the 1962 eruption and about six months before the 1988–1989 eruption. In the case of the 1962 activity, the mixed magma rapidly ascended without stagnation from the magma chamber and erupted as a sub-Plinian type. However, the juvenile materials of the 1988–1989 eruptions show distinct petrological features such as higher crystallinity of the matrix, orthopyroxene reaction rims around the olivine, and overgrowth mantle zones around Ti-magnetite phenocrysts. These features suggest that the mixed magma ascended slowly and possibly stagnated at shallower levels prior to eruption. The stagnated magma became a cap rock of the vent system and caused a series of Vulcanian eruptions. These distinct modes of magma ascent can be explained by differences in the magma supply rate. In the case of the 1962 eruption, the volume of magma that erupted in a period of less than 24 h was 7.1 × 107 m3. On the contrary, 23 explosions occurred over three months of the 1988–1989 activity and generated 1 × 105 m3 of ejecta including juvenile and non-juvenile materials. These large eruption rate differences can be attributed to the distinct ascent rates of the magma between the two eruptive activities.

scholarly journals Polysaccharide based edible coating on sapota fruit

2016 ◽  
Vol 30 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Joslin Menezes ◽  
K.A. Athmaselvi
Keyword(s):  
Shelf Life ◽  
Edible Coating ◽  
Agricultural Products ◽  
Soluble Solids ◽  
Ambient Conditions ◽  
Chemical Parameters ◽  
Organoleptic Properties ◽  
Physico Chemical ◽  
Significant Difference ◽  
Dipping Time

AbstractSapota fruits are highly perishable and have short shelf life at the ambient conditions. The edible coatings have been used on different agricultural products in order to extend their post harvest life. In the present study, the polysaccharide based edible coating made up of sodium alginate and pectin (2%) was studied on the shelf life of sapota fruits. The coating of the fruits is done by dipping method with two dipping time (2 and 4 min). The both control and coated sapota fruits were stored at refrigerated temperature (4±1°C). The physico-chemical analysis including acidity, total soluble solids, ascorbic acid, pH, weight loss, colour and firmness were measured on 1, 8, 15, 23 and 30th day of storage. There was significant difference (p≤0.05) in these physico-chemical parameters between control and coated sapota fruits with 2 and 4 min dipping time. The sensory analysis of control and coated sapota fruits showed that, the polysaccharide coating with 2 minutes dipping time was effective in maintaining the organoleptic properties of the fruits.

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