Scale deposition in water pipe due to hard water circulation often leads to various technical and economical problems. The conventional chemical treatment methods uses hazardous chemical which affects human health as well as water chemistry. This study shows the effect of physical water treatment method like pulsating electromagnetic field on water characteristics and scale reduction under different turbulent flow conditions and pipe materials. The scale removal rate was analyzed by the formation of aragonite crystal in water pipes in place of calcite crystals after electromagnetic treatment. The morphology of aragonite and calcite crystals was analyzed by field emission scanning electron microscope on different pipe materials. The water flow rate was maintained at 3, 5 and 7 L/min. After electromagnetic treatment result shows that the scale removal rate increases from pipe wall and reduces the total dissolved solids (TDS), electrical conductivity (EC), hardness and alkalinity of water. These water characteristics are further decreases on increasing the flow rate from 3 to 7 L/min. The reduction rate of these water characteristics was higher for the first 15 hours of circulation time than the remaining 15 hours. On investigating the effect of electromagnetic treatment on pipe material, it was obtained that the polyvinyl chloride (PVC) pipe is much effective than galvanized iron (GI) and copper pipes.

experiments results, measurements and other appendices

Nacre is a biological composite which is made of natural aragonite platelets and organic matrix. These platelets are embedded in the continuous matrix in a parallel and staggered pattern, forming a highly ordered hierarchical structure. The mechanical properties of nacre are far superior to those of the components. Therefore, it has received wide attention of researchers in the fields of mechanics, materials science and biology. First of all, this paper introduced the microstructure, the basic deformation mechanism and mechanical properties of nacre. The research progress of biomimetic nacre-like composites was then reviewed from three perspectives including the theoretical analysis, numerical simulation and experimental preparation. The emphasis was focused on the underlying strengthening and toughening mechanism during the deformation process, and the relationship between its structure and properties was also analyzed. Finally, the latest development direction of nacreous composites is proposed.

Regarding the generally accepted view of the minerals formed in solving the problem of ecosystem pollution, this research aims to track the role of seasonal minerals in overcoming widespread pollution problems in Lake Edku. At eleven locations inside Lake Edku and three locations in the outside the water inlets, some physical and chemical parameters that affect the formation of minerals and salts were detected seasonally. As a result of human activities from 1972 to 2020, the applied remote sensing technology showed a decrease in the area of Edku Lake by 13.3%. The saturation index (SI) of twelve minerals formed in fifty-six seasonal water samples collected from fourteen locations inside and outside the lake was estimated. The saturation index (SI) of anhydrite (ANH), gypsum (GYP), calcium phosphate (CP), magnesium phosphate (MP), calcite (CAL), aragonite (ARG), dolomite (DOL), magnesite (MGS), fluorapatite (FAP), hydroxyapatite (HAP), octacalcium phosphate (OCP), and carbonate-fluorapatite (CFAP) was calculated. The presented SI values of apatite and phosphate minerals including FAP (SI 30.63-65.65), CFAP (SI 28.14-40.02), HAP (SI 24.83-31.81), Ca3(PO4)2 (SI 23.99-25.95), OCP (SI 19.96-25.47), and Mg3(PO4)2 (SI 15.80-17.46) were high. Palmer-Roger's diagram and piper ternary diagram models reflected the abundance of NaCl in lake water with 30, 40, 46, and 75% in winter, spring, summer, and autumn, respectively. Using correlation matrix, multiple stepwise regression and cluster analysis for statistical analysis, the relationship between sedimentary minerals and outflow and drainage, as well as the role of sedimentary minerals in reducing pollution in the lake area, was outlined.

The calcareous soil of coast reef is limited in distribution, and is seldom used in engineering and lacks engineering geological research. In order to find out the spatial distribution and physical and mechanical characteristics of the calcareous soil on the coast reef, and service design, we referred to the results of previous studies on calcareous soils and collected the existing geological data in Timor-leste, and carried out field geological survey, drilling, standard penetration test and laboratory physical and mechanical test. We have studied the landform, spatial distribution, mineral chemical composition, grain size distribution, specific gravity, permeability coefficient and shear strength of calcareous soil in Timor-leste coast reef. We have summarized the physical and mechanical characteristics of calcareous soil in coast reef under the landform of sand dam and lagoon. Our study results are as following:(1)The landform of Timor-leste coast reef has its own characteristics. The land is low hill landform, the coast area is bay landform. The bay has developed sand bar, sand beach and lagoon. (2)The study area has developed six unit layers from top to bottom in the stratigraphic space:Unit 1 modern calcareous gravelly sand on the surface of sand bar, Unit 2 very soft to soft clay/silt at the lagoon surface, Unit 3 thick layers of calcareous gravelly sand in the upper part, Unit 4 silty/clayey gravelly sand/grave at the middle part, Unit 5 sitly/clay gravelly sand/grave at the lower part and Unit 6 highly to moderately weathered phyllite at the bottom. (3)The calcareous soil in Timor-leste is composed of pebbled sand lithologically and gravel locally, containing about 19% fine-grained soil. The mineral composition is mainly aragonite and calcite, followed by mica and quartz. The sediment is mainly derived from marine coral clasts and partly from terrestrial sediments. Calcareous soils, similar to atolls and barrier reefs, are also characterized by the presence of land-based sediments. (4)The special gravity of calcareous soil on coast reef is 2.70,which is larger than quartz sand, reflecting the unique special gravity formed by different mineral composition. (5)Coast-reef calcareous soil is mainly medium sand, coarse sand and gravel, but the permeability coefficient is lower than the conventional value due to the presence of more fine grains. Attention should be paid when filling. (6)The cohesion of calcareous gravelly sand of coast reef is 0, and the internal friction Angle is 33 degrees in loose state, 36 degrees in dense state, and 41 degrees in dense state, which is similar to the mature empirical evaluation of quartz gravelly sand. Our studies show that the calcareous soil in Timor-leste coast reef contains some feldspar, quartz. The mechanical strength of rock and soil is similar to that of conventional quartz sand. The empirical relationship of rock and soil parameters evaluated by the quartz sand in situ test can be applied to the calcareous soil of east Timor shore reef with reliable results. The determination of the physical and mechanical properties of calcareous soil in timor-leste coast reef provides a reference for similar types of calcareous soil geotechnical engineering applications.

Table S1. Survival rate and skeletal parameters of coral nubbins after two years of transplant experiment. Data are median +- SE.; Table S2. Physiological parameters of coral nubbins after two years of transplant experiment. Data are median +- SE.

Coral calcification is expected to decline as atmospheric carbon dioxide concentration increases. We assessed the potential of <i>Porites astreoides</i>, <i>Siderastrea siderea</i> and <i>Porites porites</i> to survive and calcify under acidified conditions in a 2-year field transplant experiment around low pH, low aragonite saturation (Ω_arag) submarine springs. Slow-growing <i>S. siderea</i> had the highest post-transplantation survival and showed increases in tissue concentrations of Symbiodiniaceae, chlorophyll <i>a</i> and protein at the low Ω_arag site. Nubbins of <i>P. astreoides</i> had 20% lower survival and higher chlorophyll <i>a</i> concentration at the low Ω_arag site. Only 33% of <i>P. porites</i> nubbins survived at low Ω_arag and their linear extension and calcification rates were reduced. The density of skeletons deposited after transplantation at the low Ω_arag spring was 15–30% lower for all species. These results suggest that corals with slow calcification rates and high Symbiodiniaceae, chlorophyll <i>a</i> and protein concentrations may be less susceptible to ocean acidification, albeit with reduced skeletal density. We postulate that corals in the springs are responding to greater energy demands for overcoming larger differences in carbonate chemistry between the calcifying medium and the external environment. The differential mortality, growth rates and physiological changes may impact future coral species assemblages and the reef framework robustness.

In this study, we used Lanistes varicus and Achatina achatina snail shell powders as a calcium source for the synthesis of calcium phosphate bioceramics by using coprecipation method and microwave irradiation method. X-Rays Diffraction Analysis, Thermal Analysis (TGA), Acid-Base back titration method and FTIR analysis of the powders of the snail shells revealed that they contain more than 98% of calcium carbonate CaCO 3 with aragonite as the major phase. Structural characterization and elucidation of synthesized bioceramics were done using X-Rays diffraction analysis, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The results have revealed that synthesized calcium phosphate bioceramics contain a mixture of Hydroxyapatite (HA: Ca 10 (PO 4) 6 (OH) 2) and apatitic Tricalcium Phosphate (TPa: Ca 9 (HPO 4) (PO 4) 5 (OH) whatever the method of synthesis. and the variety of snail shell used. The study of the antibacterial activity of synthesized bioceramics has shown that only those obtained with Lanistes varicus powder significantly inhibit the growth of Staphylococcus aureus with a lasting effect. On the other side, inhibition of growth of Klebsiella oxytoca is partial and a resistance to the antimicrobial activity of bioceramics was noticed. Thus bioceramics synthesized from Lanistes varicus snail shell powder has antibacterial property and should be used against the growth of pathogens causing dental cavities.

Рассмотрена карбонатная жильная минерализация в породах Сафьяновского медно-колчеданного месторождения (Средний Урал), представленная кальцитом, железистыми разностями магнезита и доломита, сидеритом, арагонитом. Кальцитовая, доломитовая и рассеянная сидеритовая минерализация сосредоточена в кварц-плагиоклаз-карбонат-хлоритовых породах надрудной зоны. Сидерит-магнезитовая прожилковая минерализация развита в околорудных метасоматитах на контакте с массивной медно-цинковой рудой в ассоциации с баритом, каолинитом и гидрослюдой. Рассеянная и прожилковая магнезитовая минерализация встречается в кварц-каолинит-серицит-хлоритовых подрудных метасоматитах. Жильный арагонит обнаружен в околорудных метасоматитах на глубине 240 м, новообразованный кальцит – в гидротермально-измененных известняках на глубине 275 м. Карбонаты отличаются по содержанию и распределению РЗЭ, С-О изотопии, по интенсивности ЭПР спектра Mn2+ в карбонатах. В целом зональность распределения карбонатов в околорудных породах Сафьяновского месторождения соответствует зональности уральского типа, отмеченной на некоторых колчеданных месторождениях Южного Урала, в околорудной части карбонаты представлены более железистыми разностями по сравненю с надрудной частью. Исследования показали, что карбонатная минерализация на Сафьяновском месторождении является естественным продолжением пострудных преобразований вмещающих пород и их тектонического разрушения при релаксации внутренних напряжений.

The mechanism of biological materials structure is very complex and has optimal properties compared to engineering materials. Top Neck mollusks shells, as an example of biological materials, have hierarchical structure, which 95 percent of its structure is Aragonite and 5 percent organic materials. This article detected mechanical properties of the Top Neck mollusks shell as a Nano composite using Nano-indentation method in different situations. Research findings indicate that mechanical properties of the Top Neck mollusks shell including elastic modulus and hardness are higher than a fresh one preserved in -50 centigrade and also a Top Neck mollusks shell preserved in environmental conditions. Nano-indentation test results are so close in range, overall, that hardness degree is 3900 to 5200 MPa and elastic modulus is 70 to 85 GPa.

Travertine deposits are a kind of continental carbonates that form in specific chemical, physical and biological conditions. Garab travertines in southeast of Mashhad are studied based on field, geochemistry (elemental and stable isotope analysis) and hydro-geochemistry analysis. Field and petrographic characterization led to recognize of crystalline crust, raft, foam, shrub, laminated, black mud and tufa lithofacies. These lithofacies are composed of calcite and aragonite mineralogy. They have high concentrations of Ca, Mg, S, Fe, Na and Sr and low concentration of Mn, P and Si. These lithofacies are enriched with respect to δ13C and depleted with respect to δ18O that can be related to algal origin and meteoric water, respectively. The type of Garab springs water is Ca- HCO3- - SO42- and Na- Cl. This water is saturated with respect to bicarbonate and sulfate. The water composition and dissolved ions have a close relation to geological units (carbonate and evaporite) in Garab area.

Carbon and oxygen isotope fractionation in the water-calcite-aragonite system

A ball milling approach was developed to investigate the constituents of isolated nacre tablets of the gastropod <i>Haliotis glabra</i> in aqueous suspension without additional chemical additives. Obtained particle mixtures were characterized using X-ray crystallography, scanning and transmission electron microscopy. Aragonite nanoparticles retained their crystal structure even after 14 h of ball milling. The long-term stability of the particle mixtures varied as a function of the ball milling duration. An increased milling time led to rod-like stable assemblies of aragonite nanoparticles. Selected area electron diffraction investigations revealed that the longitudinal axes in about one third of these nanoparticle-rods were oriented along the crystallographic c-axis of aragonite, indicating oriented attachment of the aragonite nanoparticles. These <i>in vitro</i> observations support the idea that a two-stage process, separated into crystallization of nanoparticles and oriented assembly of nanocrystals could also occur <i>in vivo</i>.

A cost-effective bacteria-based self-healing cementitious composite for low-temperature marine applications

Review on Researches of Aragonite Saturation State in the Southern Ocean:A Key Parameter of Southern Ocean Acidification

Egyptian Islamic Buildings are suffering from a lot of detorioration types, mainly groundwater and salt weathering which have caused the complete loss of the decorations of some of these mihrabs. Many mihrabs in egyptain islamic buildings need restoration and conservation, as islamic buildings are one of the most famouse hestorical places in egypt and over the world finding solution for this problem become very urgent. A physiochemical study using analytical techniques such as Fourier transform infrared, X-ray diffraction and scanning electron microscopy was done. This characterization study, on one hand helping us to reach for the optimum conservation and completion methods; on the other hand, the deterioration factors of mosaic were determined. All analytical methods indicated that the Al- Mansour kalaoun mosaic mihrab contains lime, Gypsum, Dolomite, Quartz, Calcite and Aragonite. It also proves that sodium chloride (halite) is the principal salt causing deterioration.

Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell powders also can be used as medicine; however, its medicinal value is much lower than that of pearl powders. Due to the feature similarity between pearl powders and shell powders, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell powders have been often posing as pearl powders in markets, which seriously infringes the interests of consumers. Identification of pearl powder was investigated by microscopic infrared reflectance spectroscopy, and pearl powder as well as shell powder was calcined at different temperatures for different time before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 °C for 30 minutes under atmospheric pressure, aragonite in pearl powder partly transformed into calcite, while aragonite in shell powder completely transformed into calcite. At the same time, the difference in phase transition between the pearl powders 'and shell powders can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl powder and shell powder. It's more meaningfully that the proposed infrared reflectance spec- troscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell powders and abalone shell powders, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl powder.

Rising atmospheric CO2 concentrations could cause a calcium carbonate subsaturation of Arctic surface waters in the next 20 yr, making these waters corrosive for calcareous organisms. It is presently unknown what effects this will have on Arctic calcifying organisms and the ecosystems of which they are integral components. So far, acidification effects on crustose coralline red algae (CCA) have only been studied in tropical and Mediterranean species. In this work, we investigated calcification rates of the CCA Lithothamnion glaciale collected in northwest Svalbard in laboratory experiments under future atmospheric CO2 concentrations. The algae were exposed to simulated Arctic summer and winter light conditions in 2 separate experiments at optimum growth temperatures. We found a significant negative effect of increased CO2 levels on the net calcification rates of L. glaciale in both experiments. Annual mean net dissolution of L. glaciale was estimated to start at an aragonite saturation state between 1.1 and 0.9 which is projected to occur in parts of the Arctic surface ocean between 2030 and 2050 if emissions follow ‘business as usual’ scenarios (SRES A2; IPCC 2007). The massive skeleton of CCA, which consist of more than 80% calcium carbonate, is considered crucial to withstanding natural stresses such as water movement, overgrowth or grazing. The observed strong negative response of this Arctic CCA to increased CO2 levels suggests severe threats of the projected ocean acidification for an important habitat provider in the Arctic coastal ocean.

Review on Researches of Aragonite Saturation State in the Arctic Ocean: A Key Parameter of Arctic Ocean Acidification

A comparative study on the natural-color golden seawater cultured pearls and the treated-color golden seawater cultured pearls were carried out by UV-Vis reflectance spectra. Furthermore, the frequency variations of v3, v1 , v2 and v4 bands of the aragonites (a crystal form of calcium carbonate) with the positions of nacreous layer and nucleus in natural or treated-color golden-color seawater cultured pearls were firstly systematically measured. The results showed that: (1) based on the results of UV-Vis reflectance spectra of natural or treated-color golden seawater cultured pearls, interestingly, it was firstly found that the natural-color golden one displays slight varied UV-Vis reflection spectra because of its different surface microstructure located on the outer nacreous layer. Meanwhile, according to the characteristic of UV-Vis reflectance spectra of treated-color golden ones, the treated-color ones were firstly classified to four categories. (2) The frequency of v2 band of aragonite in nacreous layer of natural-color or treated-color golden pearls was greater than the other one from theirs corresponding nucleus, namely A clear blue shift was observed in the former. But the other bands were not altered in the positions of nacreous layer and nucleus, and had the same valves with synthetic aragonites. Additionally, the location of absorption bands of aragonite in nacreous layer of natural or treated-color golden pearls had no frequency shift, which indicates that the behavior of color-treating had no effect on the crystal structure of golden pearls.