High SI Values Research Articles

Gynura procumbens NANOENCAPSULATION: A NOVEL PROMISING APPROACH TO COMBAT DENGUE INFECTION

Nanoencapsulation of G. procumbens with polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) is intended to increase anti-dengue activity and prevent its bioactive deterioration. The particle size of Ga-NPs was 161.00 ± 2.17 nm with a PDI value of 0.33 ± 0.02 while the particle size of Gp-NPs was 136.33 ± 0.47 nm with a PDI value of 0.34 ± 0.01. Those indicated both Ga-NPs and Gp-NPs had a homogeneous particle size distribution. Moreover, both nanocapsules showed stability at 30-100oC but were less stable at high pH and salt concentrations. Ga-NPs have a %LE (96.236 ± 1.156%) higher than the %LE of Gp-NPs (95.567 ± 0.334 %), but release of Gp-NPs is better than Ga-NPs. G. procumbens extract, Ga-NPs, and Gp-NPs exhibited anti-dengue activity with IC50 values of 11.22, 7.67, and 12.75 µg/mL, respectively. However, Ga-NPs and Gp-NPs are more potent because they have higher SI values with low cytotoxicity (CC50) compared to G. procumbens extract. Herein, nanoencapsulation of G. procumbens is proved to increase bioavailability and controlled release and allow precision targeting of bioactive compounds to enhance bioactivity activity.

Identification of “dual-site”-binding diarylpyrimidines targeting both NNIBP and the NNRTI adjacent site of the HIV-1 reverse transcriptase

Here, we reported a novel series of “dual-site” binding diarylpyrimidine (DAPY) derivatives targeting both the NNRTI adjacent site and NNRTIs binding pocket (NNIBP). The anti-HIV-1 activity results demonstrated that compound 9e (EC50 = 2.04–61.1 nM) displayed robust potencies against a panel of HIV-1 NNRTIs-resistant strains, being comparable to that of etravirine (ETR). Moreover, 9e displayed much lower cytotoxicity (CC50 = 59.2 μM) and higher SI values (4605) toward wild-type HIV-1 strain. The HIV-1 RT enzyme inhibitory activity clarified the binding target of 9e was HIV-1 RT (IC50 = 0.019 μM). Furthermore, the molecular modeling study was also investigated to give a reasonable explanation of the preliminary SARs. Further test indicated that 9e possessed significantly improved water solubility under pH 7.0 and 7.4 conditions. Additionally, the in silico prediction of physicochemical properties and CYP enzymatic inhibitory ability were investigated to evaluate their drug-like features. Consequently, compound 9e showed the highest activity and low cytotoxicity, which could be used as a lead for further modification to obtain potent HIV-1 NNRTIs.

EVALUATION OF IRREVERSIBILITY ANALYSIS FOR DIFFERENT COAL TYPES OF A THERMAL POWER PLANT

In this study, first law (energy conservation) and second law (exergy) analyzes of thermodynamics were performed for a thermal power plant. It is very important to perform energy and exergy analyzes in industrial plants. These analyzes can provide guidance on improving energy efficiency and recycling waste energy. For these analyses, coals with different contents, available in nine different countries, were considered. According to the analysis, the highest first law efficiency was determined as 53.61% in the second type of coal. The second highest law efficiency was determined as 46.67% in the 6th coal type. Environmental Destruction Index and Sustainability Index values were determined and it was seen that, the highest EDI value was obtained in the 2nd coal type and the highest SI value was obtained in the 6th coal type. According to this study, the efficiency of the 6th coal type, which has the highest second law efficiency, was observed.

Discovery of Novel Dihydrothiopyrano[4,3-d]pyrimidine Derivatives as Potent HIV-1 NNRTIs with Significantly Reduced hERG Inhibitory Activity and Improved Resistance Profiles.

Enlightened by the available structural biology information, a novel series of dihydrothiopyrano[4,3-d]pyrimidine derivatives were rationally designed via scaffold hopping and molecular hybridization strategies. Notably, compound 20a yielded exceptionally potent antiviral activities (EC50 = 4.44-54.5 nM) against various HIV-1 strains and improved resistance profiles (RF = 0.5-5.6) compared to etravirine and rilpivirine. Meanwhile, 20a exhibited reduced cytotoxicity (CC50 = 284 μM) and higher SI values (SI = 5210-63992). Molecular dynamics simulations were performed to rationalize the distinct resistance profiles. Besides, 20a displayed better solubility (sol. = 12.8 μg/mL) and no significant inhibition of the main CYP enzymes. Furthermore, 20a was characterized for prominent metabolic stability and in vivo safety properties. Most importantly, the hERG inhibition profile of 20a (IC50 = 19.84 μM) was a remarkable improvement. Overall, 20a possesses huge potential to serve as a promising drug candidate due to its excellent potency, low toxicity, and favorable drug-like properties.

Role of Thermal Exposure in Extraction of Plant Available Silicon from Neutral, Acidic and Alkaline Soils

ABSTRACT Silicon, the second most abundant element on the Earth crust, is often considered beneficial for plant nutrition. However, plant available fraction of silicon (Si) is hard to find and extract from many types soils. Soil reaction (pH), temperature and plant uptake are some of the major determinants of Si availability affecting its extraction from soil. In this experiment, neutral, acidic and alkaline soils along with plant samples (whole rice plant) have been collected from farmer’s field. Plant samples were processed following existing procedure. Soils are air dried, grinded and passed through a 2 mm pore sieve. Four levels of shaking time (0, 5, 10 and 20 minutes and denoted as S0, S5, S10, and S20,respectively) @ 120rpm (round per minute) and four levels of temperatures (room temperature or 25°C, 60°C, 80°C, and 100°C; denoted as T0, T60, T80 and T100, respectively) were employed for preparation of aliquot from soil-water (1:10 ratio) suspension. Acidic and alkaline soils have higher extractable silicon than neutral soil. Combined effect of shaking time and temperature released higher Si values than control, amongst which Si extracted from S20T100 treatment is significantly correlated with Si content in rice and have better result for all soils in common.

Environmental Hydrogeochemistry Characteristics, Controlling Factors and Groundwater Quality Assessment in Herat City, West Afghanistan

Water in Central Asia is a precious resource in the semiarid and arid environments in which people live in the region. Understanding the groundwater quality is important as it is the main factor determining its suitability for drinking and agricultural purposes. This paper presents results of a groundwater hydrochemical assessment in the Herat City by measuring its physicochemical parameters: major cations and anions, pH, total dissolved solids and electrical conductivity. In the light of progressive depletion of groundwater reservoirs and water quality deterioration, an investigation of dissolved major constituents in 27 groundwater samples was performed. The objective was detection of processes for geochemical assessment throughout the area. Herat City has been intensively inhabited during the last decenniums, leading to expansion of the residential and agricultural areas. Besides semi-aridity, rapid social and economic development stimulates greater demand for water, which is gradually fulfilled by groundwater extraction. Groundwater of the study area are characterized by the dominance of Ca + Mg over Na + K. $${\text{HCO}}_{{\text{3}}}^{ - }$$, which was found to be the dominant anion, followed by Cl– and $${\text{SO}}_{4}^{{2 - }}$$. The hydrochemical types in the area can be divided into two major groups: the first group includes mixed Ca–Mg–Cl and Ca–Cl types. The second group comprises mixed Ca–Na–HCO3 and Ca–HCO3 types. Calcite and aragonite have high SI values, which indicates precipitation as the result of evaporation, whereas dolomite shows an undersaturation state. Most of the samples are within the permissible limit of WHO standards. Interpretation of data suggests that weathering, ion exchange reactions, and evaporation to some extent are the dominant factors that determine the groundwater chemistry in the study area.

Trace Elements in Magnetite from the Pagoni Rachi Porphyry Prospect, NE Greece: Implications for Ore Genesis and Exploration

Magnetite is a common accessory phase in various types of ore deposits. Its trace element content has proven to have critical implications regarding petrogenesis and as guides in the exploration for ore deposits in general. In this study we use LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry) analyses of trace elements to chemically characterize magnetite from the Pagoni Rachi Cu–Mo–Re–Au porphyry-style prospect, Thrace, northern Greece. Igneous magnetite mostly occurs as euhedral grains, which are commonly replaced by hematite in fresh to propylitic-altered granodiorite porphyry, whereas, hydrothermal magnetite forms narrow veinlets or is disseminated in sodic/potassic-calcic altered (albite + K-feldspar + actinolite + biotite + chlorite) granodiorite porphyry. Magnetite is commonly associated with chalcopyrite and pyrite and locally exhibits martitization. Laser ablation ICP-MS analyses of hydrothermal magnetite yielded elevated concentrations in several trace elements (e.g., V, Pb, W, Mo, Ta, Zn, Cu, and Nb) whereas Ti, Cr, Ni, and Sn display higher concentration in its magmatic counterpart. A noteworthy enrichment in Mo, Pb, and Zn is an unusual feature of hydrothermal magnetite from Pagoni Rachi. High Si, Al, and Ca values in a few analyses of hydrothermal magnetite imply the presence of submicroscopic or nano-inclusions (e.g., chlorite, and titanite). The trace element patterns of the hydrothermal magnetite and especially the decrease in its Ti content reflect an evolution from the magmatic towards the hydrothermal conditions under decreasing temperatures, which is consistent with findings from analogous porphyry-style deposits elsewhere.

Synthesis of novel derivatives of 7,8-dihydro-6H-imidazo[2,1-b][1,3]benzothiazol-5-one and their virus-inhibiting activity against influenza A virus.

Influenza remains a highly pathogenic and hardly controlled human infection. The ability of selecting drug-resistant variants necessitates the search and development of novel anti-influenza drugs. Herein, we describe the synthesis and evaluation of a series of novel 2-substituted 7,8-dihydro-6H-imidazo[2,1-b][1,3]benzothiazol-5-ones 3a-k for their virus-inhibiting activity against influenza A virus. The new analogues 3a-k prepared in two steps from commercially available cyclohexane-1,3-diones were fully characterized by their NMR and mass spectral data. Among the new derivatives screened for cytotoxicity and in vitro antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1) in MDCK cells, three analogues 3i-k containing a thiophene unit were found to exhibit high virus-inhibiting activity (high SI values) and a favorable toxicity profile. The compound 3j (CC50 : >1000 μM, SI = 77) with higher potency is the best anti-influenza hit analogue for further structural optimization and drug development. The most active compounds did not inhibit viral neuraminidase and possess therefore other targets and mechanisms of activity than the currently used neuraminidase inhibitors.

English

OBJECTIVES: 1. To investigate the association between PICU shock index and mortality in children with sepsis/septic shock. 2. To explore cut off values for ICU mortality, how change in shock index over the first 6 hours of ICU admission is associated with outcome. DESIGN: Prospective study. SETTING: Single centre tertiary PICU. SUBJECTS: 50 children with a diagnosis of sepsis/septic shock. METHODS AND RESULTS: From January to June 2017, 50 children who met International pediatric Sepsis Conference of 2005 criteria of sepsis were included and the overall mortality was 32%. In age group ≤ 1 year, cut off value of SI at 0 hour was 2.16, relative risk of mortality 2.01 (95% CI, 0.67 – 5.91) and cut off value of SI at 6 hours was 1.77, relative risk of mortality 2.85 (95% CI, 0.78 – 10.37). In age group > 1 to ≤ 6 year, cut off value of SI at 0 hour was 1.43, relative risk of mortality 2.14 (95% CI, 0.71 to 6.4) and cut off value of SI at 6 hours was 1.77, odds ratio 87 (95% CI, 2.95 to 2534). In age group > 6 to 12 years, cut off value of SI at 0 hour was 2.03, relative risk of mortality 7 (95% CI, 0.67 – 72) and cut off value of SI at 6 hours was 1.56, relative risk of mortality 15 (95% CI, 2.25 – 99.7). Higher SI values were associated with mortality and increasing trend of SI increases the risk of mortality. CONCLUSION: Shock index may be a promising marker of mortality in children with sepsis/septic shock. Given the higher risk of mortality with higher SI values and with the cut off values of SI above which the risk of mortality increases, children with elevated SI values and above the cut off range for mortality may benefit from more aggressive resuscitation and intensive care.

Synthesis and Biological Evaluation of Matijin-Su Derivatives as Potential Antihepatitis B Virus and Anticancer Agents.

A series of Matijin-Su (MTS, (2S)-2-{[(2S)-2-benzamido-3-phenylpropanoyl]amino}-3-phenylpropyl acetate) derivatives were synthesized and evaluated for their anti-HBV and cytotoxic activities invitro. Six compounds (4g, 4j, 5c, 5g, 5h and 5i) showed significant inhibition against HBV DNA replication with the IC50 values in range of 2.18-8.55μm, which were much lower than that of positive control lamivudine (IC50 82.42μm). In particular, compounds 5h (IC50 2.18μm; SI 151.59) and 5j (IC50 5.65μm; SI 51.16) displayed relatively low cytotoxicities, resulting in high SI values. Notably, besides the anti-HBV DNA replication activity, compound 4j also exhibited more potent invitro cytotoxic activity than 5-fluorouracil in two hepatocellular carcinoma cell (HCC) lines (QGY-7701 and SMMC-7721), indicating that 4j may be a promising lead for the exploration of drugs with dual therapeutic effects on HBV infection and HBV-induced HCC.

Aspidosperma species as sources of anti-malarials: uleine is the major anti-malarial indole alkaloid from Aspidosperma parvifolium (Apocynaceae).

BackgroundSeveral species of the genus Aspidosperma (Apocynaceae) are used for the treatment of human malaria in Brazil and other meso- and South American countries.MethodsEthanol extract from Aspidosperma parvifolium trunk bark was submitted to acid–base extractions leading to alkaloid and neutral fractions. The alkaloid fraction was chromatographed over a silica gel column. Ethanol extract, fractions and uleine were analysed by HPLC–DAD, UPLC-ESI–MS/MS and HPLC-ESI-MicroTOF-MS. The anti-malarial activity was assayed against resistant and sensitive chloroquine Plasmodium falciparum strains by microscopic, [3H]-hypoxanthine incorporation and HRPII techniques. Cytotoxicity (CC50) was evaluated against Vero and HepG2 cell lines by the MTT technique; selectivity indexes (SI = CC50/IC50) were calculated.ResultsThe major peak in the HPLC–DAD chromatograms of the ethanol extract, alkaloid and neutral fractions suggested the presence of uleine that was isolated from the alkaloid fraction by column chromatography and was characterized by spectroscopic methods. A total of 15 alkaloids, besides uleine, were identified in the alkaloid fraction by UPLC-DAD-ESI–MS/MS and HPLC-ESI-MicroTOF-MS. The ethanol extract from Aspidosperma parvifolium and the neutral fraction were moderately active against P. falciparum strains. The alkaloid fraction and uleine disclosed high anti-malarial activity against chloroquine-resistant P. falciparum strain (IC50 < 1 µg/mL). The ethanol extract, neutral fraction and uleine showed low cytotoxicity against Vero and HepG2 cell lines (CC50 > 300 µg/mL). The alkaloid fraction showed moderate cytotoxicity to HepG2 cell line (CC50 = 74.4 µg/mL). High SI values (>10) were determined for all samples.ConclusionEthanol extract from Aspidosperma parvifolium trunk bark afforded uleine that is the major constituent of the alkaloid fraction and disclosed a good in vitro anti-malarial activity. Moreover, 15 other indole alkaloids have been identified along with uleine.

Bioactivity-guided isolation of anti-hepatitis B virus active sesquiterpenoids from the traditional Chinese medicine: Rhizomes of Cyperus rotundus

Ethnopharmacological relevanceThe rhizome of Cyperus rotundus (C. rotundus) is a well-known traditional Chinese medicine to cure hepatitis in many formulae, but the active components responsible for hepatitis have not been elucidated. According to our bioassay on HepG2.2.15 cell line in vitro, the ethanol extract of C. rotundus demonstrated potent anti-HBV activity. This current study was designed to isolate and identify the anti-HBV active constituents from the rhizomes of C. rotundus. Material and methodsBioactivity and LC-MS guided fractionation on the extract of C. rotundus using various chromatographic techniques including open-column, Sephadex LH-20 and semi-preparative high performance liquid chromatography led to the isolation and identification of thirty-seven sesquiterpenoids. Structural elucidation of the isolates was carried out by extensive spectroscopic analyses (UV, IR, HRMS, 1D- and 2D –NMR). The anti-HBV activity and cytotoxicity were evaluated on the HBV-transfected HepG2.2.15 cell line in vitro. The cytotoxicity effects of the isolates were assessed by a MTT assay. The secretions of HBsAg and HBeAg in the culture medium were detected by ELISA method, and the load of HBV DNA was quantified by real-time fluorescent PCR technique. ResultsFive new patchoulane-type sesquiterpenoids, namely cyperene-3, 8-dione (1), 14-hydroxy cyperotundone (2), 14-acetoxy cyperotundone (3), 3β-hydroxycyperenoic acid (4) and sugetriol-3, 9-diacetate (5), along with 32 known sesquiterpenoids were isolated from the active fractions of C. rotundus. Compounds 2 and 3 were the first cyperotundone-type sesquiterpenoids with a hydroxyl group at C-14 position. Nine eudesmane-type sesquiterpenoids (15–21 and 23–24) significantly inhibited the HBV DNA replication with IC50 values of 42.7±5.9, 22.5±1.9, 13.2±1.2, 10.1±0.7, 14.1±1.1, 15.3±2.7, 13.8±0.9, 19.7±2.1 and 11.9±0.6μM, respectively, of which, compounds 17, 21, 23 and 24 possessed high SI values of 250.4, 125.5,>259.6 and 127.5, respectively. Two patchoulane-type sesquiterpenoids (4 and 7) effectively suppressed the secretion of HBsAg in a dose-dependent manner with IC50 values of 46.6±14.3 (SI=31.0) and 77.2±13.0 (SI=1.7) μM, respectively. Compounds 2, 8, 12, 15, 17 and 25 possessed moderate activities against HBeAg secretion with IC50 values of 162.5±18.9 (SI=13.3), 399.2±90.0 (SI=10.6), 274.7±70.8 (SI=5.2), 313.9±87.5 (SI=7.2), 334.0±70.4 (SI=9.9) and 285.3±20.9 (SI=15.5)μM, respectively. ConclusionsThis is the first study to reveal the anti-HBV constituents of C. rotundus, demonstrating that the eudesmane-type sesquiterpenoids might contribute to the anti-HBV activity of the rhizomes of C. rotundus.

Synthesis of hemslecin A derivatives: A new class of hepatitis B virus inhibitors

A series of hemslecin A derivatives were synthesized and evaluated for their anti-hepatitis B virus (HBV) activities, namely, inhibiting the secretion of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and HBV DNA replication on HepG 2.2.15 cells. Most of the derivatives showed enhanced anti-HBV activities, of which compounds A1–A7, B5, C and E exhibited significant activities inhibiting HBV DNA replication with IC50 values of 2.8–11.6μM, comparable to that of the positive control, tenofovir. Compounds A1–A3, A5, B5, and C displayed low cytotoxicities, which resulted in high SI values of 89.7, 55.6, 77.8, >83.4, >55.8, and >150.5, respectively.

Stunting delays maturation of triceps surae mechanical properties and motor performance in prepubertal children

Malnutrition can lead to possible irreversible consequences in the development of muscle function and some of them are yet poorly characterized. The present study evaluated the mechanical properties of the triceps surae and motor performance in stunted (S) and eutrophic (E) prepubertal children (9years±6months). Height-for-age ratio was used as indicator of stunting due to early malnutrition, according to the World Health Organization. Torque was determined by maximal voluntary contractions (MVC) and musculotendinous (MT) stiffness was achieved through quick-release tests to obtain MT stiffness index (SI(MT)) and passive stiffness (K (p)) from linear MT stiffness-torque relationships. Percutaneous supramaximal electrically elicited contractions determined twitch torque (Pt) and electromechanical delay (EMD). Motor performance was evaluated by balance test. S group presented significantly lower MVC and a trend of lower Pt values indicating lower capacities to develop force under voluntary or induced conditions. Significantly higher SI(MT) and EMD values were observed, while K (p) and motor performance in balance were significantly lower. Higher SI(MT) values have been reported previously in youngest prepubertal children, indicating that immature activation capacities can mask MT stiffness assessment during voluntary contractions, taking into consideration the higher EMD values as a measure of muscle stiffness contribution. Lower K (p) may indicate a delay in the maturation of tendinous tissue in S group, influencing motor performance in balance. The present study shows that malnutrition leads to adaptation of intrinsic MT elastic properties, but depends on the level of the observed structure.

Truncated phosphonated C-1′-branched N,O-nucleosides: A new class of antiviral agents

Truncated phosphonated C-1′-branched N,O-nucleosides have been synthesized in good yields by 1,3-dipolar cycloaddition methodology, starting from N-methyl-C-(diethoxyphosphoryl)nitrone 7. Preliminary biological assays show that β-anomers are able to inhibit HIV in vitro infection at concentrations in the micromolar range. Higher SI values with respect to AZT indicated that the compounds were endowed with low cytotoxicity.

Synthesis and biological assay of 4-aryl-6-chloro-quinoline derivatives as novel non-nucleoside anti-HBV agents

A series of 4-aryl-6-chloro-quinoline derivatives were synthesized and evaluated for their anti-hepatitis B virus (HBV) activities, namely the abilities to inhibit the secretion of HBV surface antigen (HBsAg), HBV e antigen (HBeAg), and replication of HBV DNA in HepG 2.2.15 cells. Most of the compounds exhibited moderate inhibitory activity against the secretion of HBsAg and HBeAg. Nine compounds (3, 5, 6, 7, 10, 14, 17, 20, 24) showed significant inhibition against HBV DNA replication with IC50 values in the range of 4.4–9.8μM, which were comparative to that of positive control tenofovir. Of them, compounds 10, 17, and 20 had low cytotoxicities, resulting in high SI values, >551.2, >143.7, and >284.5, respectively.

Contact and respiratory sensitizers can be identified by cytokine profiles following inhalation exposure

There are currently no validated animal models that can identify low molecular weight (LMW) respiratory sensitizers. The Local Lymph Node Assay (LLNA) is a validated animal model developed to detect contact sensitizers using skin exposure, but all LMW respiratory sensitizers tested so far were also positive in this assay. Discrimination between contact and respiratory sensitizers can be achieved by the assessment of cytokine profiles. In a LLNA using the inhalation route, both contact and respiratory sensitizers enhanced proliferation in the draining lymph nodes. The question was if their cytokine profiles were affected by the route of exposure. Male BALB/c mice were exposed head/nose-only during 3 consecutive days to the respiratory sensitizers trimellitic anhydride, phthalic anhydride, toluene diisocyanate, hexamethylene diisocyanate (HDI), and isophorone diisocyanate; the contact sensitizers dinitrochlorobenzene (DNCB), oxazolone (OXA) and formaldehyde (FA), and the irritant methyl salicylate (MS). Three days after the last exposure the draining lymph nodes were excised and cytokine production was measured after ex vivo stimulation with Concanavalin A. Skin application was used as a positive control. After inhalation exposure the respiratory sensitizers induced more interleukin-4 (IL-4) and interleukin (IL-10) compared to the contact sensitizers, whereas the contact sensitizers, except formaldehyde, induced relatively more interferon-γ (IFN-γ) production. When IL-4 and IFN-γ were plotted as a function of the proliferative response, it was shown that IL-4 could be used to identify respiratory sensitizers, except HDI, at concentration levels inducing intermediate stimulation indices. HDI could be distinguished from DNCB and OXA at high SI values. In contrast, contact sensitizers could only be identified when IFN-γ was measured at high stimulation indices. The skin positive control, tested at high concentrations, showed comparable results for IL-4 and IL-10, whereas IFN-γ levels could not be used to discriminate between respiratory and contact sensitizers. The contact sensitizer FA and the irritant MS did not induce significant cytokine production after inhalation and skin exposure. In conclusion, the respiratory LLNA is able to identify and distinguish strong contact and respiratory sensitizers when simultaneously proliferation and cytokine production are assessed in the upper respiratory tract draining LNs.

Fine Dry Grinding of Zeolite in a Laboratory Ball Mill

AbstractThis paper presents the importance and usage of natural zeolites, which was recently recognized in the industry. Therefore, the grinding properties of natural zeolite were studied with the emphasis on a kinetic study in a ball mill. The experimental mill employed was laboratory sized, 200 mm diameter, 191 mm length, providing a total mill volume of 6000 cm3, with a total mass of 5.62 kg of steel balls of 25 mm diameter with a charge of 20% of the mill volume and with a rotation speed of 76 rpm. The breakage parameters were determined by using single sized feed fractions of −850+600 μm, −600+425 μm, and −425+300 μm for the zeolite samples. The Si (specific rate of breakage) and Bi, j (primary breakage distribution) values were obtained for those feed size fractions in order to predict the product size distributions by simulation for comparison to the experimental data. From the experimental results, Si values increased as the feed sizes became coarser, i.e., the highest Si value was 0.85 min−1 for −850+600 μm, while the lowest Si value was 0.65 min−1 for −425+300 μm feed ground in the mill. The Bi, j values obtained for the zeolite sample were γ=0.84, ϕ=0.61, and β=4.25. The breakage parameters obtained showed that the zeolite is broken faster than quartz and slower than calcite and barite in terms of the aT values reported previously at the same experimental conditions. The simulations of the product size distributions of zeolite were in good agreement with the experimental data using a standard ball mill simulation program. The slowing‐down effect was also seen in the mill after 4 min. of grinding.

Determination of the Breakage and Wetting Parameters of Calcite and Their Correlations

AbstractThis paper presents the breakage and wetting parameters of calcite mineral obtained experimentally and establishes a correlation between these characteristic parameters. The breakage parameter obtained from the different feed sizes of grinding is the specific rate of breakage (Si). The wettability parameter, obtained from surface chemistry‐based processes such as contact angle measurements or flotation methods, is the critical surface tension of wetting of a solid or mineral (γc). Calcite mineral, studied for the determination of the above parameters and their correlations, was ground in a laboratory‐size ceramic ball mill with dry, wet and chemically aided grindings and tested extensively to determine the γc values by using a contact angle goniometer and a newly designed micro‐column flotation cell. The highest Si value obtained was 0.35 min−1 for sodium dodecyl sulfate (SDDS)‐aided grinding, and the lowest Si value was 0.26 min−1 for dry grinding of the −600+425 feed in the mill. The γc values for calcite were obtained as 34.0–34.9 mN/m for SDDS‐treated calcite surfaces, 29.9–31.4 mN/m for sodium oleate‐treated surfaces and &gt;72 mN/m for both dry and wet ground products whose surfaces were not treated chemically. Some correlations were established between the Si and γc parameters; as the Si increases, γc decreases, indicating that relatively more hydrophobic surfaces are broken faster for the largest sizes, resulting in higher Si values with more fines (lower γ of Bi, j) in the finer size distribution region (i.e. −150 μm).

Geological setting and petrochemistry of the Narracoota Volcanics, Capricorn Orogen, Western Australia

Abstract The Narracoota Volcanics, part of the early Proterozoic Glengarry Group on the northern margin of the Yilgarn Block, were deformed and metamorphosed between 1.7 and 1.8 Ga ago and then covered by sediments of the Padbury Group (1.6–1.7 Ga). Although most of the Glengarry Group is in-place on granitoid basement, pre-Padbury Group deformation produced large-scale south-vergent recumbent folds in parts of the region, so that much of the Glengarry Group is at least parautochthonous. It was probably deposited on substantially thinned continental crust. The Narracoota Volcanics in the southern, autochthonous part of the region are dominated by thick (4 km), chemically uniform successions of tholeiites, differing from MORB only in their slightly low Ti/Fe and Zr/Fe. Further north, autochthonous and parautochthonous Narracoota Volcanics are dominated by ultramafic schists of probably pyroclastic origin. Mafic volcanic rocks associated with these schists range up to 58% SiO2 and are very poor in Ti and Zr. They resemble some boninites of the western Pacific. The southern volcanic rocks are interpreted to reflect open-system fractionation of mantle-derived magmas in large, subcrustal magma chambers, similar to those postulated at oceanic ridges. The high Si-values and low Ti- and Zr-values in more northerly mafic rocks may reflect hydrous melting and second-stage melting, respectively. The geochemical similarities of some of the Narracoota Volcanics to boninites suggest an arc(subduction-related)-origin for these rocks, but there is little evidence from the regional geological setting to support this. Origin in a continental-rifting environment in which the sub-continental mantle was locally H2O-rich is the favoured interpretation. The thick sequences of MORB-like volcanic rocks, their geochemical differences from continental tholeiites and the thin-skinned deformation suggest that continental rifting was of major dimensions in the region.