Producing Black Pepper (Piper Nigrum L. cv. ‘Kuching’) Rootstock in a Deep-Water Culture Hydroponic System

Stem cutting is the common planting material for black pepper (Piper nigrum L.) farmers mainly because the method is cheap, easy to obtain, and produces satisfactory number of new plantlets, which are relatively genetically uniform to their parent. However, soil propagation of stem cuttings renders both the stem and developing roots susceptible to soil borne pathogens, ultimately compromising the quality of the plant. Good quality rootstock of the new plant promotes faster, safer, and better black pepper plant establishment. Hydroponic farming thus offers a good platform for producing quality rootstock of the new plants and has gained importance to many farmers due to its flexibility in manipulating plant growth conditions and timely pathogen management, thus safer, healthier, and faster growth. This study investigated the growing media suitable for rootstock growth of P. nigrum L. cv. ‘Kuching’ and compared the rooting ability between stem cuttings with adventitious roots at the time of planting and stem cuttings without any root at the time of planting. In a laboratory setting, a total of 210 stem cuttings were hydroponically planted in seven nutrient compositions, with each nutrient composition containing an equal number of stem cuttings with adventitious roots at the time of planting and stem cuttings without any root at the time of planting. Hoagland solution supplemented with 0.005 mM potassium silicate solution (T4) and Hoagland solution supplemented with 2 mM salicylic acid solution (T6) showed faster root initiation whereas T1 (Hoagland solution only) produced the highest increment in root length followed by T6. The least suitable nutrient composition was T5 [T4 + 6 mL of 1 M Ca (NO3)2.4H2O solution]. The total number of roots was highest in plants from stem cuttings which had some adventitious roots at the time of planting, whereas roots in plants from stem cuttings which did not have any root at the time of planting, increased in root length faster than plants withstem cuttings which had adventitious roots at the time of planting.

Synthesis and Characterization of Industrial Casting Sand Based Silica Aerogel

In this study, a commercial foundry sand (Seydisehir Eti Aluminium Co. Inc.) was provided as the starting material. Using this supplied casting sand, silica aerogel production was carried out by sol-gel method. Starting materials chemical components were determined by doing XRD and XRF analyses to starting industrial casting sand respectively. After analysing studies, sodium silicate solution was produced from commercial casting sand. During silica aerogel synthesize, 5 different pH degree was investigated including 2-4-6-8 and 9. Silica aerogel modification (Super hydrophobic) was made by choosing the optimum pH value. Afer then, on the synthesized experiment sample, FT-IR, BET, SEM and contact angle characterization studies were realised respectively. As a result of preliminary experiments done with different pH experiments, sample with the lowest density was determined as pH 8 value. Keywords: Casting sand, Sol-gel, Silica aerogel

Strength and Microstructure Characteristics of Blended Fly Ash and Ground Granulated Blast Furnace Slag Geopolymer Mortars with Na and K Silicate Solution

Mineral geopolymer binders can be an attractive and more sustainable alternative to traditional Portland cement materials for special applications. In geopolymer technology the precursor is a source of silicon and aluminium oxides, the second component is an alkaline solution. In the synthesis of geopolymer binders the most commonly used alkaline solution is a mixture of sodium or potassium water glass with sodium or potassium hydroxide or silicate solution with a low molar ratio, which is more convenient and much safer in use. In this paper, we present the influence of sodium or potassium silicate solution on the physical and mechanical properties of fly ash and ground granulated blast furnace slag-based geopolymer mortars. Mercury intrusion porosimetry and microstructural observation allowed for comparing the structure of materials with a different type of alkaline solution. The evolution of compressive and flexural tensile strength with time determined for composites using 10%, 30% and 50% slag contents (referring to fly ash mass) was analysed. The tests were performed after 3, 7, 14 and 28 days. It was observed that, as the amount of slag used increases in the precursor, the strength of the material grows. Mortars with the sodium alkaline solution were characterised by a higher strength at a young age. However, the values of strength 28 days were higher for geopolymers with potassium alkaline solution reaching 75 MPa in compression. Geopolymer mortar microstructure observation indicates a high matrix heterogeneity with numerous microcracks. Matrix defects may be caused by the rapid kinetics of the material binding reaction or shrinkage associated with the drying of the material.

Silica-Bacterial Cellulose Composite Aerogel Fibers with Excellent Mechanical Properties from Sodium Silicate Precursor

Forming fibers for fabric insulation is difficult using aerogels, which have excellent thermal insulation performance but poor mechanical properties. A previous study proposed a novel method that could effectively improve the mechanical properties of aerogels and make them into fibers for use in fabric insulation. In this study, composite aerogel fibers (CAFs) with excellent mechanical properties and thermal insulation performance were prepared using a streamlined method. The wet bacterial cellulose (BC) matrix without freeze-drying directly was immersed in an inorganic precursor (silicate) solution, followed by initiating in situ sol-gel reaction under the action of acidic catalyst after secondary shaping. Finally, after surface modification and ambient drying of the wet composite gel, CAFs were obtained. The CAFs prepared by the simplified method still had favorable mechanical properties (tensile strength of 4.5 MPa) and excellent thermal insulation properties under extreme conditions (220 °C and −60 °C). In particular, compared with previous work, the presented CAFs preparation process is simpler and more environmentally friendly. In addition, the experimental costs were reduced. Furthermore, the obtained CAFs had high specific surface area (671.3 m²/g), excellent hydrophobicity, and low density (≤0.154 g/cm3). This streamlined method was proposed to prepare aerogel fibers with excellent performance to meet the requirements of wearable applications.

The Effect of Gel-Type Contributions in Lime-Sand Bricks, Alkali-Activated Slags and CEMI/CEMIII Pastes: Implications for Next Generation Concretes

Lime-sand bricks of different ages were investigated using IR-spectroscopy, thermogravimetry, and X-ray diffraction/scattering. After subtraction of the dominant quartz contribution (80%), the IR spectra show the absorption peaks of the hydrothermally formed binder phases. The spectra also show the alteration of the binder during ageing under atmospheric conditions by the influence of CO2 forming carbonate and a condensed SiO2-gel (secondary gel). The alteration could also be proven in X-ray pattern, obtaining a separation between crystalline CSH and amorphous contributions in the freshly produced lime-sand brick, too. Here, the formation of CSHamorph could be understood as a precursor state (primary gel) to the crystallization of CSH phases. X-ray patterns of aged bodies of alkali-silicate solution activated slags (AAS), CEM-I/CEM-III pastes, and CEM-I concrete indicate that in all cases a similar amorphous CSH-type phase (CSHamorph) was formed, which is responsible for the hardening properties as the glue. The main X-ray peak of CSHamorph obtained using CuKα-radiation with a usual diffractometer is observed between 24° and 35° 2 Theta with maximum at about 29° 2 Theta, whereas it appears much more broadly distributed between 15° and 35° 2 Theta with maximum between 26° and 28° 2 Theta for a geopolymer body prepared using the reaction of alkali-silicate solution and metakaolin (AAMK). This is due to the network formed by siloxo and sialate units in the case of AAMK, given that any crystallization can be ruled out. The origin of increasing mechanical strength during the ageing of AAS mortars must be due to further crosslinking of the preformed siloxo chains. Thermal treatment up to 800 °C leads to a complete loss of any mechanical strength of the CEM pastes due to the destruction of crystalline CSH-phases, whereas geopolymer bodies maintain their strength. Implications for next generation concrete include that cement clinker could be completely replaced by using a using alkali silcate solution technology for gel formation.

Granulated Expanded Glass Manufacturing Method Using Electromagnetic Waves

The paper presents experimental results obtained in the process of experimental manufacture in a microwave oven of lightweight granulated glass aggregates. The process was conducted to obtain the highest dimensional class (between 18-23 mm), the almost spherical shape of the aggregates being facilitated by cold processing of raw spherical pellets (between 11-15 mm) containing the powder mixture formed by glass waste, borax. calcium carbonate, aqueous sodium silicate solution and water addition and then rotation of the high electromagnetic wave susceptible ceramic crucible containing raw pellets during the heat treatment at temperatures between 822-835 ºC. In terms of quality, the expanded glass aggregate granules are almost similar to those manufactured in conventional rotary kilns heated by burning fuel, having the following characteristics: bulk density of 0.17 g/cm3, compressive strength of 2.2 MPa, thermal conductivity of 0.047 W/m·K, water absorption of 1 vol. % and pore size between 0.3-0.6 mm. The experimental product has not yet been tested as a raw material in the manufacture of some light weight concretes, but the use of similar granulated glass aggregates manufactured in the world confirms the ability of this aggregate type to produce light weight and energy efficient concretes for building construction.

Granulated Expanded Glass Manufacturing Method Using Electromagnetic Waves

The paper presents experimental results obtained in the process of experimental manufacture in a microwave oven of lightweight granulated glass aggregates. The process was conducted to obtain the highest dimensional class (between 18-23 mm), the almost spherical shape of the aggregates being facilitated by cold processing of raw spherical pellets (between 11-15 mm) containing the powder mixture formed by glass waste, borax. calcium carbonate, aqueous sodium silicate solution and water addition and then rotation of the high electromagnetic wave susceptible ceramic crucible containing raw pellets during the heat treatment at temperatures between 822-835 ºC. In terms of quality, the expanded glass aggregate granules are almost similar to those manufactured in conventional rotary kilns heated by burning fuel, having the following characteristics: bulk density of 0.17 g/cm3, compressive strength of 2.2 MPa, thermal conductivity of 0.047 W/m·K, water absorption of 1 vol. % and pore size between 0.3-0.6 mm. The experimental product has not yet been tested as a raw material in the manufacture of some light weight concretes, but the use of similar granulated glass aggregates manufactured in the world confirms the ability of this aggregate type to produce light weight and energy efficient concretes for building construction.

Remediation of Annular Gas Migration along Cemented Wellbores Using Reactive Mineral Fluids: Experimental Assessment of Sodium Bicarbonate and Sodium Silicate-Based Solutions

Achieving zonal isolation along wellbores is essential for upholding the containment integrity of subsurface reservoirs and preventing fluid seepage to the environment. The sealing performance of Portland cements conventionally used to create barriers can be severely compromised by defects like fractures or micro-annuli along casing–cement–rock interfaces. A possible remediation method would be to circulate reactive fluids through compromised cement sections and induce defect clogging via mineral precipitation. We assess the sealing potential of two prospective fluids: sodium bicarbonate and sodium silicate solutions. Reactive flow-through experiments were conducted on 6-m-long cemented steel tubes, bearing ~20-μm-wide micro-annuli, at 50 °C and 0.3–6 MPa fluid pressure. For the sodium bicarbonate solution (90 g/kg-H2O), reactive flow yielded only a minor reduction in permeability, with values remaining within one order. Injection of sodium silicate solution (37.1 wt.%, SiO2:Na2O molar ratio M= 2.57) resulted in a large decrease in flow rate, effectively reaching the setup’s lower measurement limit in hours. However, this strong sealing effect can almost certainly be attributed to gelation of the fluid through polymerisation, rather than defect clogging via mineral precipitation. For both fluids investigated, the extent of solids precipitation resulting from single-phase injection was less than anticipated. This shortfall is attributed to ineffective/insufficient liberation of Ca-ions from the alkaline phases in the cement.