PETROLOGICAL INVESTIGATION OF CARBONATE ROCKS FROM THE IONIAN ZONE (ETOLOAKARNANIA, WESTERN GREECE)

The petrographic features of the carbonate rocks from the Ionian Zone in the Etoloakarnania Prefecture are presented. They are represented by limestones with minor dolomite. The limestones include: (i) wackestones (or sparse micrites), with poor presence of allochems within a mud matrix; (ii) packstones (or packed micrites) with increasing levels of carbonate grains that are still surrounded by micrite matrix, and (iii) grainstones (or sparites) containing allochems that are cemented with sparry calcite crystals, while the mud matrix is absent. Bioclasts are the dominant carbonate components in most of the samples accompanied by infrequent pelloids, intraclasts, lithoclasts and ooids. Crystalline limestones were not identified. Quartz, apatite, barite, anhydrite, halite, clay minerals, magnetite and ilmenite have been determined as accessory phases. The results show that mineralogical and petrographic features of the analyzed carbonate rocks are related to their evolution during the development of the Ionian Zone from a shallow-marine platform to a deep water basin

Efficacy of resin infiltration to mask post-orthodontic or non-post-orthodontic white spot lesions or fluorosis - a systematic review and meta-analysis.

OBJECTIVE The present review systematically analyzed clinical studies investigating the efficacy of resin infiltration on post-orthodontic or non-post-orthodontic, white spot lesions (WSL), or fluorosis. MATERIALS Five electronic databases (Central, PubMed, Ovid MEDLINE, Ovid EMBASE, LILACS) were screened. Article selection and data abstraction were done in duplicate. No language or time restrictions were applied. Outcomes were visual-tactile or DIAGNOdent measurements. RESULTS Eleven studies with 1834 teeth being affected in 413 patients were included. Nine studies were randomized control trials, one a prospective cohort study, and one had an unclear study design. Meta-analysis could be performed for "resin infiltration vs. untreated control," "resin infiltration vs. fluoride varnish," and "resin infiltration without bleaching vs. resin infiltration with bleaching." WSL being treated with resin infiltration showed a significantly higher optical improvement than WSL without any treatment (standard mean difference (SMD) [95% CI] = 1.24 [0.59, 1.88], moderate level of evidence [visual-tactile assessment]) and with fluoride varnish application (mean difference (MD) [95% CI] = 4.76 [0.74, 8.78], moderate level of evidence [DIAGNOdent reading]). In patients with fluorosis, bleaching prior to resin infiltration showed no difference in the masking effect compared to infiltration alone (MD [95% CI] = - 0.30 [- 0.98, 0.39], moderate level of evidence). CONCLUSION Resin infiltration has a significantly higher masking effect than natural remineralization or regular application of fluoride varnishes. However, although the evidence was graded as moderate, this conclusion is based on only very few well-conducted RCTs. CLINICAL RELEVANCE Resin infiltration seems to be a viable option to esthetically mask enamel white spot lesions and fluorosis

Impact of Water Salinity on the Yield of Production Well: Forward Osmosis Seawater Pretreatment

The process of oil extraction often requires pumping water into the injection well to dislodge oil which is finally collected in the production well. Aquifer, river and sea waters have been for injection to stimulate oil production in both on and off-shore reservoir. Recent research by British Petroleum (BP) found a strong relationship between the salinity of the injected water and oil recovery. The lowest the water salinity is the highest the oil recovery rate. In other words, using low salinity water in the injection well will increase oil reservoir productivity. Since low salinity water is not always available especially in remote areas, desalination would guarantee the removal of high salinity from seawater for injection well use. Nowadays, it is possible to produce fresh water from seawater by appropriate desalination process. Reverse Osmosis (RO) is one of the desalination processes which are widely used in the production of freshwater from seawater. Although the process is highly reliable and efficient, RO cost is rather expensive. One of the technologies which have been suggested as an alternative to RO seawater desalination is NF-NF/BWRO hybrid membrane system. The proposed system involves using two different types of high permeability and rejection rate membrane for the removal of high salinity from seawater. Pilot plant and simulation results showed the high efficiency and cost-effectiveness of NF-NF/BWRO technology for seawater desalination. The process can be competitive to RO and most importantly more economical. Furthermore, NF-NF/BWRO system is modular and can be retrofitted in any existing plant. It is expected that the implementation of NF-NF/BWRO technology has the potential to produce low salinity water at lower cost than RO and boost oil recovery from the injection well

Forward osmosis pretreatment of seawater to thermal desalination: High temperature FO-MSF/MED hybrid system

Forward osmosis (FO) seawater pretreatment was proposed for the removal of scale ions from seawater to the thermal desalination plant. In the current study, previously developed models were applied to estimate the effectiveness of FO pretreatment in the removal of divalent ions from feed solution to MSF/MED at elevated temperatures. The simulation results showed that the water and salt flux across the FO membrane increased with increasing the seawater salinity. However, for given seawater salinity, the water and salt flux across the FO membrane decreased with increasing the FO recovery rate. It was found that the concentration of Ca2+, Mg2+ and SO42- ions increased with increasing the operating temperature in the thermal plant but decreased with increasing the recovery rate of the FO pretreatment. Additionally, an FO pretreatment-MED Scale Index (FMSI) was developed to determine the required FO recovery rate and avoids scale problems at different MED operating temperatures. Initially, Ryznar Scale Index (RSI) of the feed solution was calculated for different MED operating temperatures. Then, RSI was plotted against the FO recovery rates and the desirable FO recovery rate was determined from the plot based on the operating temperature of the MED plant. The scale index was also applied to determine the required mixing ratio of NF permeate-makeup water in the NF-MED desalination hybrid system. The application of the FO pretreatment-MED Scale Index has the potential to reduce the required time and resources to determine the desirable FO/NF pretreatment ratio of feed water to the MED plant. © 2014

Low Level Laser Therapy With an 810-nm Diode Laser Affects the Proliferation and Differentiation of Premature Osteoblasts and Human Gingival Fibroblasts In Vitro

Introduction: Photomodulation is a promising strategy for optimizing tissue healing, but its photomodulatory effects on the synergistic cellular metabolism of gingival and bony tissues remain largely unknown. The aim of the present study was to evaluate the photomodulatory effects of a diode laser (810 nm) on osteoblasts, HGFs and their co-cultures in vitro. Methods: Primary cultures of HGFs, cultures of immature osteoblastic cells (MG63) and their cocultures were irradiated with a diode laser (810 nm), 15 J/cm2. Cell cultures were examined for cellular proliferation (MTT assay), viability (FDA/PI staining) after 24, 48 and 72 hours and cell differentiation (qPCR of collagen type 1a - COL1a and alkaline phosphatase expressions - ALP) after 7 days. Results: Photomodulation with an 810-nm diode laser increased cell proliferation at all time points. COL1a gene expression increased both in HGF and co-cultures. ALP expression was up-regulated in osteoblastic cultures, but co-cultures with fibroblasts negated this response. Conclusion: The 810-nm diode laser positively affected cell proliferation and viability in all experimental groups. The statistically significant increased COL1a gene expression at 7 days after irradiation both in the irradiated HGF and co-cultures suggests that low-level laser therapy (LLLT) stimulated extracellular matrix (ECM) formation signaling in both cell types. © 2021. All Rights Reserved

Heat transfer and evaporation in geothermal desalination units

The heat transfer of air-water-vapour mixtures in a desalination plant, using the aero-evapo-condensation process, has been studied theoretically and experimentally. The present unit consists of a falling-film evaporator and condenser, made of polypropylene. It was designed to work at low temperatures (of 60-90°C) utilizing geothermal energy. A model for heat-and-mass transfers in the plant is developed, resulting in a set of classical equations. Two experimental pilot studies were used. The latter, installed in France and the south of Tunisia, were supplied by fuel and geothermal energy respectively. The influences of different thermal and hydrodynamic parameters on the unit performances were investigated. Experimental results were compared with the model predictions. From this comparison, it can be learnt that the model is well able to predict the trends of the heat-and-mass characteristics of the evaporator. The present process was compared with other desalination techniques. It was shown that in areas where geothermal water resources are available, the process is promising either for cooling or desalting geothermal water.Geothermal energy Desalination Evaporator Horizontal tubes Falling film Evaporation Heat transfer Economic evaluation