Propagation of Nano Sized CDG Deep into Porous Media

Enhanced Oil Recovery (EOR) technologies become more critical as number of mature oilfields grows continually. Among the variety of chemical EOR methods, conventional application of the polymer-based solutions occupies the largest space. One of the most perspective technologies is application of polymeric fluids that do not contain a 3D polymer structure. Among such compositions, colloid dispersion systems are especially worth mentioning as they could be simultaneously used for water-oil mobility ratio control as well as permeability profile modification. Presented study considers the propagation of colloidal dispersed gels in porous media under different mineralization of formation water. For this purpose were conducted rheological measurements, Particle size distribution and Propagation experiments. The results show that divalent ions cause higher viscosity reduction due to the formation a more severe electrolyte and average particle size decreased with ionic strength increment. The presence of divalent ions improves the propagation probably by cause of repulsion forces increase.

Gold nanoparticles affect the cryopreservation efficiency of in vitro-derived shoot tips of bleeding heart

The popularity of nanoparticles (NPs) is continuously increasing. To date, however, there has been little research on the application of NPs in plant cryopreservation, i.e. storage of tissues in liquid nitrogen (LN). The aim of this study is to analyze the effect and evaluate the usefulness of gold nanoparticles (AuNPs) in regard to cryobiology studies. In vitro-derived shoot tips of Lamprocapnos spectabilis ‘Valentine’ were cryopreserved with the encapsulation-vitrification protocol. Gold nanoparticles (at 10–30 ppm concentration; 13 nm in size) were added either into the preculture medium; to the protective bead matrix during encapsulation; or to the recovery medium after rewarming of samples. The control plants were produced from cryopreserved explants non-treated with nanoparticles or treated with colloid dispersion medium without NPs. A non-LN-treated standard was also considered. The influence of AuNPs on the cryopreservation efficiency was determined by evaluating the recovery rate of explants and their morphogenic response; the membrane stability index (MSI); the concentration of pigments in shoots; and the antioxidant enzymes activity. The genetic stability of the plant material was evaluated using Start Codon Targeted Polymorphism (SCoT) markers. It was found that 10 ppm of AuNPs added into the alginate bead matrix improved the recovery level of LN-derived shoot tips (70.0%) compared to the non-NPs-treated cryopreserved control (50.5%). On the other hand, the presence of nanoparticles in the recovery medium had a deleterious effect on the survival of explants. AuNPs usually had no impact on the MSI (73.9–85.9%), except for those added into the recovery medium at the concentration of 30 ppm (decline to 55.8%). All LN-derived shoots were shorter and contained less chlorophyll and carotenoids than the untreated standard. Moreover, the application of AuNPs affected the enzymatic activity in L. spectabilis. Minor genetic variation was found in 8.6% of plants if AuNPs were added either into the preculture medium (at 10 and 20 ppm) or to the alginate matrix (at 30 ppm). In conclusion, AuNPs added at a lower concentration (10 ppm) into the protective bead matrix can significantly improve the cryopreservation efficiency in L. spectabilis with no alternation in the DNA sequence.

Redox-driven colloidal mobility and its effects on carbon cycling in temperate paddy soils

<p>Rice paddy soils are known to represent a large proportion of global terrestrial carbon (C) stocks (ca.10 Pg), accumulating organic C in the topsoil due to cultivation under submerged conditions. Apart from the limited mineralization under anoxic soil conditions resulting from frequent field flooding, other mechanisms involving the dynamic interactions between organic C and redox-active minerals particularly Fe (oxy)hydroxides, together with the transport of organic C to deep mineral horizons, can lead to long-term C stabilization. Our previous studies have shown that up to 30-50 g m<sup>-2</sup> of dissolved organic C (DOC, defined as <450 nm) and 25-40 g m<sup>-2</sup> of Fe<sup>2+</sup> may be mobilized and translocated into the subsoil over a rice cropping season in temperate rice paddies, contributing to an increase in belowground C stocks. However, little is yet know on influence of frequent redox fluctuations on the contribution of colloidal organo-mineral associations to C mobilization and accrual in paddy subsoils.</p><p>We hypothesized that (i) redox fluctuations may lead to an overall increase in colloid dispersion (via reductive dissolution of Fe oxides, changes in soil pH, as well as neoformation of colloidal organo-mineral associations), and that (ii) colloidal mobility may represent an important C input to paddy subsoils. In order to evaluate the effects of redox fluctuations on colloid dynamics in situ, water-dispersible fine colloids (WDFC) were isolated from soils collected from different horizons along two profiles opened in adjacent plots under long-term paddy (P) and non-paddy (NP) management in NW Italy. Moreover, WDFC were also isolated from anaerobically-incubated topsoil samples to evaluate the changes in colloid dispersion under reducing conditions as a function of management. Colloidal size-fractionation and their elemental compositions were evaluated by asymmetric flow field-flow fractionation (AF4) coupled with OCD or ICP-MS. </p><p>Our results evidenced that redox cycling favours colloidal stability in the topsoils, with a preferential dispersion of the smallest-sized colloidal C (<30 nm and 30-240 nm fractions), even though larger-sized colloidal C (>240 nm) contributes predominantly to the WDFC. Consequently, under long-term paddy management colloidal dispersion and transport along the soil profile were probably responsible for the lower amounts of colloidal C (and Fe) observed in the Ap topsoil horizons of P with respect to NP, as well as for the significant accumulation of colloidal C in correspondence with the Brd subsoil horizons just beneath the plough pan. These illuvial horizons were also particularly rich in small-sized (30-240 nm) colloidal Fe, Al and Si possibly due to mineral phase changes induced by redox fluctuations.</p><p>Our findings therefore indicate that downward mobilization of colloidal C associated with Fe (hydr)oxides (e.g. coprecipitates) or small aluminosilicate minerals, rather than dissolved organic C, may represent an important process driving organic C accrual in paddy subsoils. However, further insights are still required to entangle the contribution of the different mechanisms involved.</p>

The Nitrogen Distribution Characteristics of Different Colloidal Dispersion Complex in Yitong River Sediments

The sediment of the Yitong which is located in the middle of Jilin Province is selected as the object of study. The distribution characteristics of nitrogen content in colloidal dispersion complex were studied using the improved Qiulin colloid dispersion grouping method, . The results showed that the absolute amount of nitrogen in G0>G2. Among the group of complex of < 10μm, the absolute amount of nitrogen in G2 group is maximum, but the contribution to the sediment nitrogen stability is minimal. The total weight (total G) of complex of < 10 μm accounted for about 27% of the sediment, but the content of nitrogen accounted for about 49% of the total sediment nitrogen, which indicated the importance of the complex of < 10 μm to the stabilization of the sediment nitrogen.