Total Silicon Content Research Articles

Silicon Improves Soil Environment and Promotes Crop Growth under Compound Irrigation via Brackish Water and Reclaimed Water

Not only is solving freshwater resource shortages effective but also an important measure for realizing the sustainable development of agriculture through the development and use of unconventional water resources. This pot experiment investigated the role of exogenous silicon in the risk of secondary soil salinization and the growth physiology of Lvxiu pakchoi cabbage under irrigation by using brackish water alone (BW), reclaimed water alone (RW), and compound irrigation with brackish water and reclaimed water at a ratio of 1:1, as well as the distribution of silicon in a soil–crop system. The results showed that with the extension of the spraying period of silicon fertilizer, the electrical conductivity (EC) decreased under 1:1 compound irrigation. The pH values in all treatments ranged from 7.95 to 8.10 without a potential risk of alkalization. Spraying silicon fertilizer had a positive effect on increasing the ratio of exchangeable potassium to sodium in soil. Spraying silicon fertilizer significantly reduced the percentage of exchangeable sodium (ESP) and the sodium adsorption ratio (SAR) in soils irrigated using BW, and increased the soil ESP and SAR under compound irrigation and RW irrigation, but these factors did not exceed the threshold of soil salinization. The proper application of silicon fertilizer had no significant effect on the total silicon content in the soil but increased the total silicon content in the plants to some extent. In addition, the yield was improved through proper silicon fertilizer application. In summary, exogenous silicon has positive effects on soil physical and chemical properties and crop growth, and relieves secondary salinization risk under compound irrigation via brackish water and reclaimed water.

Silicon improves root functioning and water management as well as alleviates oxidative stress in oilseed rape under drought conditions.

The aim of our study was to examine how silicon regulates water uptake by oilseed rape roots under drought conditions and which components of the antioxidant system take part in alleviating stress-induced ROS generation in the roots. The study analyzed mainly the changes in the roots and also some changes in the leaves of oilseed rape plants, including total silicon content, relative water content, osmotic potential, stomatal conductance, abscisic acid level, the accumulation of BnPIP1, BnPIP2-1-7 and BnTIP1 aquaporins, and the activity of antioxidant enzymes. It was shown that plants growing in well-watered conditions and supplemented with silicon accumulate smaller amounts of this element in the roots and also have higher relative water content in the leaves compared to the control plants. It was demonstrated for the first time that BnTIP1 accumulation in oilseed rape roots is reduced under drought compared to wellwatered plants, and that this effect is intensified in plants supplemented with silicon. In addition, it was shown that silicon supplementation of oilseed rape increases catalase activity in the roots, which correlates with their high metabolic activity under drought and ultimately stimulates their growth. It was shown that silicon improves water balance in oilseed rape plants subjected to drought stress, and that an important role in these processes is played by tonoplast aquaporins. In addition, it was demonstrated that silicon reduces oxidative stress in roots under drought conditions by increasing the activity of catalase.

Phytolith occluded organic carbon in Fagopyrum (Polygonaceae) plants: Insights on the carbon sink potential of cultivated buckwheat planting.

Crop cultivation has great potential to result in a phytolith carbon sink and can play important roles in the long-term stable carbon sequestration of terrestrial ecosystems. Buckwheat, an important multigrain crop with a very long cultivation history, is widely planted around the world. The phytolith carbon sink potential of buckwheat planting is still limited in the in-depth understanding of biogeochemical carbon sequestration in croplands. In order to estimate the phytolith carbon sink potential of buckwheat planting, in the present study, six species including 17 populations of Fagopyrum plants were selected as study materials. Firstly, their phytoliths were extracted using the wet oxidation method; then, the phytolith-occluded organic carbon (PhytOC) contents were determined using the spectrophotometry method; finally, the phytolith carbon sink potential of buckwheat planting was estimated. Results showed the following: 1) The PhytOC content range of the six Fagopyrum species studied was 0.006%~0.038%, which was significantly lower than that of rice, wheat, sugarcane, and some cereal and oil crops. There were significant differences in total silicon, phytolith, and PhytOC content of Fagopyrum plants among the different species, different organs (root, stem, and leaf), and different living forms (annual, partly perennial, and completely perennial). There were significant positive relationships between PhytOC and phytolith content and between phytolith and total silicon content. 2) The average phytolith carbon sequestration rate of Fagopyrum esculentum and Fagopyrum tataricum planting was 2.62 × 10-3 and 1.17 × 10-3t CO2 hm-2·a-1, respectively, being approximately equal to that of terrestrial shrub vegetation. 3) The global total amount of phytolith carbon sequestration of buckwheat planting reached 5,102.09 t CO2 in 2018, and the Chinese total amount of phytolith carbon sequestration of buckwheat cultivation was 624.79t CO2 in 2020. The phytolith carbon sink of buckwheat planting had significant potential for playing obvious roles in the carbon cycle. The present results are of great significance in crop phytolith studies and provide important references for phytolith carbon sink potential estimation of farmland ecosystems.

Evaluation of Si Fertilization and Spraying of Nano-K and Ca on Si Content, Si Uptake, and Si Use Efficiency of Rice

A study was carried out in Al-Tale’a town (District of 41-Al-Husseiniyah, south of Hilla City) in the Babylon Governorate of Iraq from the 15th of June to the 19th of November 2020 to evaluate the effects of Si fertilization and Nano-K and Nano-Ca spraying on the content and uptake of Si and its use efficiency in rice crops. This experiment was conducted in an effort to determine the This experiment was conducted between the 15th and 19th of June, 2020. (Oryza sativa L.). The research was done using a split-plot design, and the parameter distribution was carried out using a randomized full blocks approach (RCBD). The supplied amounts of Si fertilizer served as the major plot, while the concentrations of nano-fertilizer concentrations served as the secondary plot. There were a total of sixteen treatments, and each was replicated three times. The analysis and interpretation of the research’s results were conducted using statistical tools. The amount of silica fertilizer was the first variable with four levels: 0 kg ha-1, 100 kg ha-1, 200 kg ha-1, and 300 kg ha-1. The second component was the application of nano-fertilizers, which contained four separate treatment options: the control, nano-potassium, nano-calcium, and nano-(K + Ca). The only treatment option that did not include nano-fertilizers was the control. According to the findings, silica fertilization at a rate of 300 kg ha-1 led to the highest silicon content in grain and straw (0.961 and 0.952)%, as well as the maximum Si-uptake in grain and straw (55.363, 122.337 and 177.700) kg Si ha-1. The use of nano foliar spraying with potassium and calcium produced the highest grain silicon concentration (44.540) kg Si ha-1 and total silicon content among all treatments (153.339) kg Si ha-1. Strong interaction between Si fertilization and foliar spraying with nano-K and Ca led in the largest mean of total Si-uptake (179.268) kg Si ha-1 and silicon utilization efficiency. This was accomplished by a mixture of silica fertilizer and nano-potassium and calcium foliar sprays. This outcome was achieved by using silica fertilizer in combination with nano-potassium and calcium-containing foliar sprays (66.95)%.

Valuable cobalt/biochar with enriched surface oxygen-containing groups prepared from bio-waste shrimp shell for efficient peroxymonosulfate activation

Converting bio-waste shrimp shell into valuable cobalt-based biochar with enriched surface oxygen-containing groups for high-efficiency ciprofloxacin degradation via advanced oxidation technology is achieved. • The synergy of in-situ formed CoSiO x and biochar in the designed composites. • As-fabricated composites can efficiently activate PMS for CIP degradation. • Activation mechanism followed by multi-reaction pathways. • Degradation pathways and toxicity assessment were systematically researched. Efficient activation of peroxymonosulfate using cobalt-based heterogeneous catalytic composites to produce highly reactive oxygen species for the degradation of toxic organic pollutants has been paid increased attention nowadays; however, the concept of transforming bio-waste into valuable cobalt-based catalysts remains much room to undertake. Herein, the natural marine bio-waste shrimp shell with a high total silicon content was firstly utilized as functional matrix for cobalt species to activate peroxymonosulfate for environmental remediation is reported. Remarkably, benefiting from the cooperative synergistic effect between in-situ formed CoSiO x and biochar, onto which is enriched in abundant surface functional groups, the resultant Co-SSP-700 with high specific surface area and outstanding stability exhibited prominent activity for ciprofloxacin degradation, namely nearly 90% of ciprofloxacin could be achieved within 40 min. EPR spectroscopy and scavenger tests were conducted out to investigate oxygen species, illustrating that the possible activation mechanism of PMS mainly ran through the multi-reaction pathways, whereas the radical mechanism induced by SO 4 •− and O 2 •− was a determining factor. More importantly, the intermediates of ciprofloxacin degradation were identified by LC-MS analyses to propose the possible degradation pathways and the aquatic toxicity of intermediates was explored by constructing a QSAR model.

Fertilisation with Potassium Silicate Exerted Little Effect on Production Parameters of Cucumbers Exposed to UV and Drought

(1) Background: Cucumbers are highly sensitive to drought and UV-B radiation, which may also act synergistically. Silicon is a beneficial element for plants, as it can alleviate negative effects of different environmental constraints. Studies revealed that fertilisation of cucumbers with silicon showed a variety of positive effects, which increased plant vitality. The aim of this study was to investigate the role of potassium silicate in shaping cucumber traits and in mitigating potential adverse effects of drought and UV radiation. (2) Methods: Plants were exposed to different treatments regarding water availability, UV radiation, and potassium silicate addition. During the experiment, the level of plant-available silicon and total silicon content in the soil were monitored along with soil moisture. At the end of the experiment, the leaf element composition, leaf biochemical and leaf physiological properties were analysed in addition to growth and production parameters of these cucumbers. (3) Results: Among the three studied factors, insufficient water supply had the most negative impact on measured parameters, causing a significant decline in cucumber growth and production. UV radiation had an adverse impact on various studied parameters, while potassium silicate addition negatively affected production parameters. Fertilisation with potassium silicate increased the level of plant-available silicon in the soil and leaf silicon content. (4) Conclusions: Fertilisation with potassium silicate exerted little impact on production parameters of cucumbers exposed to ambient UV radiation and drought. Significant interactions between the studied factors were detected for the aboveground vegetative plant parts.

Designer Glasses—Future of Photonic Device Platforms

AbstractThe intentional inclusion of key atomic elements in a purpose designed glass helps to achieve unprecedented control over the ultrafast laser written circular waveguide morphology and refractive index change. Behavioral response of glass constituents to ultrafast laser in 14 different commercial silicate glasses having various compositions are studied. Viscosity, aluminum to alkaline earth+alkali ratio, and total silicon content within the glass are the prime control factors for producing waveguides with high circularity and refractive index change. Drawing on this knowledge, the designer glass is successfully fabricated from an empirical formula that facilitates maintaining circular waveguide morphology, high refractive index over fast feed rates, and amorphous composition.

Development and Validation of a Spectrophotometric Procedure for Determining Silicon in Common Horsetail (Equisetum arvense L.) Herb

Background: An accurate, simple and selective UV-spectrophotometric method was developed for the estimation of silicon in medicinal plant raw material – horsetail herb (Equisetum arvense L.) of Russian origin. Methods: The determination of total silicon content in terms of silicon dioxide (SiO2) by the direct ultraviolet–visible (UV-Vis) spectrophotometry method (at a wavelength of 815 ± 5 nm) in the horsetail herb is based on the formation of yellow-colored silicomolybdic acid, and its further reduction to molybdenum blue. Results: Recoveries were found to be in the range of 100.2 to 105.1% and %RSD was less than 2%. Conclusion: The developed method is accurate, specific, precise within an interval 2-12% and suitable for the analysis of horsetail herb commercial samples.

Postharvest application of potassium silicate improves keeping quality of banana

ABSTRACTGRAS (General-Regarded-As-Safe) compounds play a considerable role in food industry to secure the food safety and environmental sustainability. Soluble silicon (Si) acts as a disease control agent for many plants. Climacteric pattern of ripening and postharvest diseases limit the shelf life of banana during transportation to local and overseas destinations. The ability of banana fruit to absorb Si upon postharvest dip treatment and if so, the absorption of Si confers any effects on disease reduction and keeping quality, were investigated. Banana dipped in 1500 µg mL−1 silicon for 20 minutes showed longer shelf life among different Si concentration × dipping time treatment combinations. Si treatment resulted significantly lower rates of ethylene production, respiration and delayed time taken for fungal rot development compared to non Si-treated (control) fruit. Total soluble silicon content in peel tissues was significantly higher [0.54% dry weight (dw)] in Si-treated versus control fruit (0.13% dw). Si treatment had no effect on total Si content, total soluble solids (TSS) content, titratable acidity (TA) or antioxidant activity in banana fruit pulp. This indicates that dip-treatment allowed Si to penetrate and remain in peel without reaching fruit pulp while extending the shelf life without altering the organoleptic properties of banana fruit pulp.

Phase Composition, Structure, and Hardening of Alloys Containing 6% (Ca + Si) in the System Al–Ca–Si–Zr–Sc

Thermo-Calc calculations and experimental methods (optical and electron scanning microscopy, and electron microprobe analysis) were used to study the phase composition of alloys of the Al–Ca–Si–Sc–Zr system with the same scandium and zirconium contents (0.1 and 0.25 wt %, respectively) and the same total silicon and calcium content (6 wt %). It was shown that the hardening due to the precipitation of nanoparticles of the phase Al3(Zr, Sc)–L12 reaches a maximum after annealing at 300–450°C in alloys within the phase region (Al) + Al4Ca + Al2Si2Ca, where (Al) stands for a solid solution based on aluminum. In alloys within this region, almost all of the zirconium and scandium are contained in (Al), and the silicon content of the alloys is minimum. However, Zr and Sc additions have almost no effect on hardening in alloys within the (Al) + (Si) + Al2Si2Ca phase region. The aluminum–calcium eutectic has an essentially finer structure than that of aluminum–silicon.

Uptake of Silicon by Sugarcane from Applied Sources May Not Reflect Plant-Available Soil Silicon and Total Silicon Content of Sources.

Soils of the tropics and sub-tropics are typically acid and depleted of soluble sources of silicon (Si) due to weathering and leaching associated with high rainfall and temperatures. Together with intensive cropping, this leads to marginal or deficient plant Si levels in Si-accumulating crops such as rice and sugarcane. Although such deficiencies can be corrected with exogenous application of Si sources, there is controversy over the effectiveness of sources in relation to their total Si content, and their capacity to raise soil and plant Si concentrations. This study tested the hypothesis that the total Si content and provision of plant-available Si from six sources directly affects subsequent plant Si uptake as reflected in leaf Si concentration. Two trials with potted cane plants were established with the following Si sources as treatments: calcium silicate slag, fused magnesium (thermo) phosphate, volcanic rock dust, magnesium silicate, and granular potassium silicate. Silicon sources were applied at rates intended to achieve equivalent elemental soil Si concentrations; controls were untreated or lime-treated. Analyses were conducted to determine soil and leaf elemental concentrations. Among the sources, calcium silicate produced the highest leaf Si concentrations, yet lower plant-available soil Si concentrations than the thermophosphate. The latter, with slightly higher total Si than the slag, produced substantially greater increases in soil Si than all other products, yet did not significantly raise leaf Si above the controls. All other sources did not significantly increase soil or leaf Si concentrations, despite their high Si content. Hence, the total Si content of sources does not necessarily concur with a product's provision of soluble soil Si and subsequent plant uptake. Furthermore, even where soil pH was raised, plant uptake from thermophosphate was well below expectation, possibly due to its limited liming capacity. The ability of the calcium silicate to provide Si while simultaneously and significantly increasing soil pH, and thereby reducing reaction of Si with exchangeable Al3+, is proposed as a potential explanation for the greater Si uptake into the shoot from this source.

Utilization of Silicon Fertilizer Application on Pepper Seedling Production

The purpose of this research was study the rate and application method of calcium silicate (Ca2SiO4) fertilizer appropriated for pepper seedling production. This study was divided into two experiments. Experiment 1, the effect of Ca2SiO4 fertilizer application in pepper seedling by mixed in growing media was arranged in 2x6 factorials in Completely Randomized Design (CRD) with 4 replications. Factor A was seed preparation methods (seed primed with Ca2SiO4 fertilizer at a rate 2 g L-1 and non-seed primed) and factor B was application rates of Ca2SiO4 fertilizer at 0, 30, 60, 120, 240 and 480 kg ha-1. Experiment 2, the effect of Ca2SiO4 fertilizer application in pepper seedling by foliar method was arranged in 2x6 factorials in CRD with 4 replications. Factor A was seed preparation methods and factor B was application rates of Ca2SiO4 fertilizer at 0, 2, 4, 6, 8 and 10 g L-1. All experiments data were collected such as plant growth and total silicon content in plant at 28 days after sowing (DAS). From experiment 1, the results showed that seed primed with Ca2SiO4 fertilizer application at a rate 120 kg ha-1 gave the good plant growth and total silicon in plant. Experiment 2, the results showed that seed primed with Ca2SiO4 fertilizer application at a rate 2 g L-1 gave the highest of plant growth and total silicon in plant. To conclude, Ca2SiO4 fertilizer application can be employed for enhancing plant growth of pepper seedling and increasing silicon content in plant.

샥스핀 가공 중 사용된 메타규산나트륨 분석

메타규산나트륨은 우리나라 식품첨가물공전에 등록되어 있는 품목으로 식용유지류의 여과보조제의 목적 이외에는 사용할 수 없으며, 최종식품 완성 전에 제거하도록 규정되어 있다. 그러나 최근 샥스핀 등 수산물에 중량 증량의 목적으로 메타규산나트륨을 불법 사용하는 사례가 지속적으로 발생함에 따라 메타규산나트륨의 사용 여부를 판별할 수 있는 분석법의 필요성이 대두되고 있다. 그러나 메타규산나트륨의 수용액은 강알칼리성용액으로 식품에 첨가되면 해리되어 그 자체로 분석할 수 없으며, 규소 양의 측정을 통해 간접적인 방법으로 추정할 경우 시료 자체에 천연적으로 존재하는 규소와 구분해야 하는 어려움이 있다. 따라서 본 연구에서는 메타규산나트륨의 첨가 여부를 판별하기 위한 기초 자료 확보를 위해 메타규산나트륨 수용액에 가공되지 않은 상어지느러미를 침지하여 중량의 증가, pH 및 규소 함량 변화를 측정하였고, 이를 모니터링 결과와 비교하였다. 그러나 Robberecht 등(7)의 연구결과 6종의 어류에서 규소가 1.77-84.19 mg/kg의 범위에서 검출된 결과에서 알 수 있듯이, 수산물의 종류와 개체 간에 규소 함량의 편차가 크게 나타날 수 있기 때문에 향후 샥스핀의 규소 함량 모니터링을 지속적으로 수행하여 데이터베이스를 좀 더 보강할 필요가 있을 것으로 판단되며, 그 이후에 대조군과 pH, 수분 및 규소 함량 비교를 통해 메타규산나트륨 사용여부를 유추해 볼 수 있을 것으로 생각된다. According to the Korea Food Additives Code, sodium metasilicate is permitted for use as a filtering agent for edible oils and fats. Sodium metasilicate is currently used as a food additives to increase the weight of shark fins. In this study, we developed an analytical method to quantify sodium metasilicate in food. Sodium metasilicate content was estimated by measuring the moisture content, pH and silicon content of shark fins. Silicon content was analyzed using inductively coupled plasma-optical emission spectrometry (ICP-OES) following microwave-assisted digestion with <TEX>$HNO_3$</TEX> (65%) and <TEX>$H_2O_2$</TEX> (30%). Shark fin total silicon content was <TEX>$7.17{\pm}8.92mg/kg$</TEX>, while the soluble silicon content was <TEX>$2.34{\pm}3.80mg/kg$</TEX>. After soaking raw shark fin in an aqueous solution of sodium metasilicate, fin weight, pH and silicon content were measured. These results would be used as the basic information for shark fins safety management.

The decrease in silicon concentration of the connective tissues with age in rats is a marker of connective tissue turnover

Silicon may be important for bone and connective tissue health. Higher concentrations of silicon are suggested to be associated with bone and the connective tissues, compared with the non-connective soft tissues. Moreover, in connective tissues it has been suggested that silicon levels may decrease with age based upon analyses of human aorta. These claims, however, have not been tested under controlled conditions. Here connective and non-connective tissues were collected and analysed for silicon levels from female Sprague–Dawley rats of different ages (namely, 3, 5, 8, 12, 26 and 43weeks; n=8–10 per age group), all maintained on the same feed source and drinking water, and kept in the same environment from weaning to adulthood. Tissues (696 samples) were digested in nitric acid and analysed by inductively coupled plasma optical emission spectrometry for total silicon content. Fasting serum samples were also collected, diluted and analysed for silicon. Higher concentrations of silicon (up to 50-fold) were found associated with bone and the connective tissues compared with the non-connective tissues. Although total silicon content increased with age in all tissues, the highest connective tissue silicon concentrations (up to 9.98μg/g wet weight) were found in young weanling rats, decreasing thereafter with age (by 2–6 fold). Fasting serum silicon concentrations reflected the pattern of connective tissue silicon concentrations and, both measures, when compared to collagen data from a prior experiment in Sprague–Dawley rats, mirrored type I collagen turnover with age. Our findings confirm the link between silicon and connective tissues and would imply that young growing rats have proportionally higher requirements for dietary silicon than mature adults, for bone and connective tissue development, although this was not formally investigated here. However, estimation of total body silicon content suggested that actual Si requirements may be substantially lower than previously estimated which could explain why absolute silicon deficiency is difficult to achieve but, when it is achieved in young growing animals, it results in stunted growth and abnormal development of bone and other connective tissues.

Silicon and boron differ in their localization and loading in bone

Silicon and boron share many similarities, both chemically and biochemically, including having similar effects on bone, although their mechanisms of action are not known. Here we compared the loading of silicon and boron into bone, their localization and how they are influenced by age (growth & development), to obtain further clues as to the biological effects of these elements and, especially, to see if they behave the same or not. Bone samples were obtained from two different studies where female Sprague Dawley rats had been maintained on a normal maintenance diet for up to 43weeks. Total bone elemental levels were determined by ICP-OES following microwave assisted acid digestion. Silicon and boron levels in the decalcified bones (i.e. the collagen fraction) were also investigated. Silicon and boron showed marked differences in loading and in their localization in bone. Highest silicon and lowest boron concentrations were found in the under-mineralized bone of younger rats and lowest silicon and highest boron concentrations were found in the fully mineralized bone of the adult rat. Overall, however total bone silicon content increased with age, as did boron content, the latter mirroring the increase in calcium (mineral) content of bone. However, whereas silicon showed equal distribution in the collagen and mineral fractions of bone, boron was exclusively localized in the mineral fraction. These findings confirm the reported association between silicon and collagen, especially at the early stages of bone mineralization, and show that boron is associated with the bone mineral but not connective tissues. These data suggest that silicon and boron have different biological roles and that one is unlikely, therefore, to substitute for the other, or at least boron would not substitute for Si in the connective tissues. Finally, we noted that silicon levels in the mineral fraction varied greatly between the two studies, suggesting that one or more nutritional factor(s) may influence the loading of Si into the mineral fraction of bone. This and the nature of the interaction between Si and collagen deserve further attention.

Caracterização e adição de poeira de aciaria elétrica em ferro-gusa

O objetivo desse trabalho é estudar a redução dos óxidos de ferro e zinco contidos na poeira de aciaria elétrica (PAE), na forma de briquete, por um banho de ferro-gusa líquido com elevado teor de silício. A poeira de aciaria foi caracterizada através das seguintes técnicas: análise química, análise granulométrica, difração de raios X, microscopia eletrônica de varredura (MEV) e análise de microrregiões por EDS. Os experimentos foram realizados em escala de laboratório em um forno tubular vertical, com um fluxo argônio. Periodicamente, foram retiradas amostras do banho para a verificação dos teores de silício do banho. Os óxidos de zinco, ferrita de zinco e outros óxidos foram reduzidos, volatilizados e coletados pelo sistema de limpeza de gás, montado na parte superior do forno. Foi possível obter picos no EDS, que identificaram uma composição de, aproximadamente, 55,00% de zinco, além de conseguir reduzir o FeO pelo silício e carbono do ferro-gusa.

Synthesis and Catalytic Properties of Hybrid Mesoporous Materials Assembled from Polyhedral and Bridged Silsesquioxane Monomers

A family of hybrid mesoporous materials with high temperature stability was obtained by the suitable covalent combination of two types of siloxane precursors. Specifically, cubic T(8) polyhedral oligomeric (POSS) and aryl bridged silsesquioxane monomers (1,4-bis(triethoxysilyl)benzene, BTEB) play the role of nanobuilders. An optimal molar ratio of the two precursors (5-25 mol% of total silicon content from the BTEB disilane) generated a homogenous, highly accessible, and well-defined mesoporous material with hexagonal symmetry and narrow pore-size distribution. Physicochemical, textural, and spectroscopic analysis corroborated the effective integration and preservation of the two different nanoprecursors, thereby confirming the framework of the mesoporous hybrid materials. A post-synthesis amination treatment allowed the effective incorporation of amino groups onto the aryl linkers, thereby obtaining a stable and recyclable basic catalyst for use in C-C bond-formation processes.

Instant food products as a source of silicon

Silicon is a trace element for humans, and is absorbed from food in the form of orthosilicic acid. Instant food products are part of a constantly growing market of convenience foods, which have not been evaluated yet as sources of silicon. In this study the total and soluble silicon contents in different instant food products were determined by using graphite furnace atomic absorption spectrometry (GF-AAS). A selection of instant products commercially available in Wroclaw were analyzed: soups, main courses, coffee drinks, jellies and puddings. Total silicon contents in soups, main courses and coffee drinks ranged widely and reached the values: 0.10–30.20, 0.63–37.91 and 0.21–13.37mg/serving, respectively. These products contained 0.05–1.26mg of soluble silicon per serving. The total silicon content in jellies and puddings did not exceed 0.36mg and 2.42mg/serving, respectively. Among the analyzed desserts the highest level of soluble silicon was found in chocolate puddings: 0.36–0.41mg/serving. The silicon level in servings of the studied instant products when prepared with the appropriate amount of water was also estimated. The mean content of silicon determined in samples of drinking water from Wrocław and the vicinity, which was used for the estimation, amounted to 7.09mg/l. The total silicon content in ready-to-eat products ranged from 1.32 to 39.21mg/serving. In conclusion, some of the analyzed instant foods contained very high amounts of silicon, however the content of the soluble, and hence available, form of this element was low.

Silicon speciation by gas chromatography coupled to mass spectrometry in gasolines

A method for the speciation of silicon compounds in petroleum products was developed using gas chromatography coupled to mass spectrometry (GC-MS). Prior to analysis, several precautions about storage and conservation were applied for all samples. In spiked gasoline samples, limits of detection between 24 and 69 μg kg(-1) for cyclic siloxanes (D(4)-D(6)) and between 1 and 7 μg kg(-1) for other species were obtained. In this study, cyclic siloxanes (D(n)) and one ethoxysilane were quantified for the first time in petroleum products by a specific method based on response factor calculation to an internal standard. This method was applied to four samples of naphthas and gasolines obtained from a steam cracking process. Cyclic siloxanes were predominant in four investigated samples with concentrations ranging between 101 and 2204 μg kg(-1). Cyclic siloxane content decreased with an increase in their degree of polymerization. During a steam cracking process, silicon concentrations determined by GC-MS SIM (single ion monitoring) significantly increase. This trend was confirmed by ICP-OES (inductively coupled plasma optical emission spectroscopy) measurements but a difference on the total silicon content was observed, certainly highlighting the presence of unknown silicon species. GC-MS SIM method gives access to the chemical nature of the silicon species, which is crucial for the understanding of hydrotreatment catalyst poisoning in the oil and gas industry.

Periodic mesoporous organosilicas with co-existence of diurea and sulfanilamide as an effective drug delivery carrier

In this article we report the synthesis of new periodic mesoporous organosilicas (PMOs) with the co-existence of diurea and sulfanilamide-bridged organosilica that are potentially useful for controlled drug release system. The materials possess hexagonal pores with a high degree of uniformity and show long-range order as confirmed by the measurements of small-angle X-ray scattering (SAXS), N 2 adsorption isotherms, and transmission electron microscopy(TEM). FT-IR and solid state 29Si MAS and 13C CP MAS NMR spectroscopic analyses proved that the bridging groups in the framework are not cleaved and covalently attached in the walls of the PMOs. It was found that the organic functionality could be introduced in a maximum of 10 mol% with respect to the total silicon content and be thermally stable up to 230 °C. The synthesized materials were shown to be particularly suitable for adsorption and desorption of hydrophilic/hydrophobic drugs from a phosphate buffer solution at pH 7.4.