Low Reduction Degree Research Articles

The Impact of Tadbir as a Pre-Application Treatment of Medicinal Plants on Their Chemical Profiles and Biological Activities in Traditional Persian Pharmacy

Based on basic traditional medicine practice, many plants undergo primary treatments to improve their pharmacological characteristics or to attenuate unwanted or unfavorable features of drugs before incorporating them into drug formulations. These treatments are called “Tadbir” in Traditional Persian Medicine (TPM). The purpose of these processes includes but is not limited to eliminating unnecessary compounds, excluding harmful properties such as toxicity and poignancy, and improving their overall natural properties and effectiveness. Here, the effect of vinegar and acetic acid treatment on three herbal specimens, including Carum carvi L. fruits (CC), Trachyspermum ammi (L.) Sprague fruits (TA), and Nigella sativa L. seeds (NS) were investigated. The treated and non-treated samples were subjected to essential oil and methanol extraction. Further, to assess the alterations in the essential oil constituents caused by Tadbir, samples were analyzed by Gas Chromatography/Mass Spectrometry (GC/MS) and HPTLC fingerprinting techniques. Total phenol and flavonoid content and DPPH free radical scavenging activity of methanol extracts were evaluated. As a result of the treatments, TA extracts showed significant rise in phenol and flavonoid contents. Total phenol content increased from 98.50±1.01 in non-treated increased to 181.20±0.27 mg GAE/g Ext. in the vinegar-treated TA fruit extract and total flavonoid showed a rise from 8.97±1.12 to 12.89±0.41 mg QE/g Ext. This may be the reason behind its lower IC50 values in DPPH free radical scavenging assay. Interestingly, Tadbir treatment of TA fruits with 4% acetic acid, lowered the IC50 value from 1019.42±75.65µg/mL in non-treated control to 274.2±17.22 µg/mL; while vinegar caused a lower degree of reduction in IC50 value (369.4±5.54 µg/mL) in DPPH free radical scavenging assay. However, CC fruit extracts, showed a decrease in phenolic content; while demonstrating an increase in flavonoids. Interestingly, phenol and flavonoid contents were significantly enhanced in treated NS seed extracts. The results of all extracts were found significantly different (p<0,05) from each other and the non-treated control. The conclusive results of the present study may partly justify the pre-application of Tadbir treatments of medicinal plants in traditional pharmacy.

In vitro evaluation of the platelet adhesion and interferon-γ production capacity of mononuclear cells coming in contact with a hydrophilic polymer-embedded polysulfone dialyzer

BackgroundA polysulfone dialysis membrane containing both polyvinylpyrrolidone (PVP) and the novel hydrophilic polymer (NV polymer) has been developed in an attempt to modify the blood contact surface of the membrane. In the present study, we performed an in vitro evaluation of the NV polymer-embedded membrane (NV membrane), focusing on the adhesion of blood cells to the membrane and the interferon (IFN)-γ production capacity of peripheral blood mononuclear cells coming in contact with the membrane.MethodsTwo membranes, the NV membrane and the conventional membrane embedded with PVP alone (CX), were evaluated simultaneously by dividing the porcine blood obtained from the same animal into two portions. The blood cell adhesion to the membranes was evaluated by measuring the hemoglobin concentrations and lactate dehydrogenase (LDH) activities in the eluates extracted from the membranes. The IFN-γ production capacity in response to phytohemagglutinin stimulation of mononuclear cells coming in contact with either membrane was evaluated.ResultsBoth the hemoglobin concentration and LDH activity, corrected by excluding erythrocytes from the eluate, were about 25% lower in the eluate from the NV membrane than in the eluate from the CX membrane. The IFN-γ production capacity of the mononuclear cells coming in contact with dialysis membrane remained unchanged for the case of the NV membrane, while it decreased for the case of the CX membrane.ConclusionsA lower degree of adhesion of blood cells to the membrane and a lower degree of reduction in the IFN-γ production capacity of mononuclear cells coming in contact with the membrane were observed for the NV membrane, as compared with the PVP membrane, which may suggest improved biocompatibility of the NV membrane.

Robust and multifunctional MXene/rGO composite aerogels toward highly efficient solar-driven interfacial evaporation and wastewater treatment

Given the ever-growing global water resource crisis, exploiting multifunctional materials featuring with high interfacial solar steam generation efficiency and good purification capability to achieving seawater desalination and wastewater treatment simultaneously are highly desired, yet it still remains a huge challenge to date. Herein, robust and multifunctional MXene/rGO (MRGA) and polydopamine & chitosan @ MRGA (CS&PDA@MRGA, CPM) three-dimensional composite aerogels with distinct interconnected cellular architecture were developed via a facile ice template-assisted chemical reduction self-assembly technology and subsequent sequential deposition modification. Due to the favorable graphene oxide-assisted assembly behavior, the resultant aerogels displayed a desirable mechanical robustness along with an excellent lightweight property. Benefiting from the strong electrostatic interaction deriving from aerogel surface moieties and dye molecules, MRGA-12 exhibited a prominent adsorption capability towards various dyes and achieved a superb adsorption capacity of up to 396.05 mg/g for malachite green (MG). Moreover, by virtue of the synergistic effect between the intentionally regulated low reduction degree of rGO and the integration of PDA and CS, CPM-12 achieved a dramatically reduced evaporation enthalpy of water from 2256 to 1617.18 J/g. Accordingly, this distinct feature resulted in an extraordinary solar-driven interfacial evaporation performance with a remarkable evaporation rate of 1.86 kg/m2/h and a high evaporation efficiency of 83.28 % under 1 sun illumination. Therefore, together with the terrific oil/water separation capability, these novel MXene-based aerogels hold a great potential for high-performance solar-driven interfacial evaporation and wastewater treatment.

Varietal responses of root characteristics to low nitrogen application explain the differing nitrogen uptake and grain yield in two rice varieties.

Rice root characteristics are tightly associated with high-efficient nitrogen uptake. To understand the relationship of root plastic responses with nitrogen uptake when reducing nitrogen application for green rice production, a hydroponic experiment and a soil pot experiment were conducted under high (HN) and low (LN) nitrogen applications, using two rice (Oryza sativa L.) varieties, NK57 and YD6, three nitrogen absorption traits (total nitrogen accumulation, net NH4 + influx on root surface, nitrogen uptake via apoplasmic pathway) and root characteristics were investigated. In comparison with HN, LN significantly reduced nitrogen absorption and grain yield in both varieties. Concomitantly, there was a decrease in total root length, root surface area, root number, root volume, and root cortical area under LN, while single root length, root aerenchyma area, and root lignin content increased. The expression of OsAMT1;1 and OsAMT1;2 down-regulated in both varieties. The findings revealed that YD6 had smaller reduction degree for the three nitrogen absorption traits and grain yield, accompanied by smaller reduction degree in total root length, root surface area, root cortical area, and expression of the two genes under LN. These root characteristics were significantly and positively correlated with the three nitrogen absorption traits and grain yield, especially under LN. These results indicate that a large root system, lower reduction degree in several root characters, and high expression of OsAMT genes in YD6 explains its high nitrogen accumulation and grain yield under reduced nitrogen application. The study may provide rationale for developing varieties with low nitrogen fertilizer requirements for enabling green rice production.

Regeneration of iron fuel in fluidized beds Part II: Reduction experiments

Direct reduction of combusted iron powders using renewable energy is one of the keys to ensure a carbon-neutral iron fuel cycle. Based on (de-)fluidization experimental study in Part I, reduction experiments of micron-sized combusted iron powders using hydrogen in a lab-scale gas-fluidized bed are conducted at temperatures ranging from 500 ∘C to 650 ∘C. The effects of temperature, hydrogen velocity and concentration on the reduction performance (including reduction degree, particle morphology and size change) and sintering/defluidization behavior are investigated. Overall, a reduction degree higher than 90% is reached at a lower temperature of 500 ∘C, whereas at higher temperatures the serious problem of particle sintering is encountered, which leads to quick defluidization and thus a relatively low reduction degree. Temperature has been found to have a pronounced effect on the sintering and reduction behavior, while the effect of gas velocity on the reduction process is negligible. SEM images show that the reduced powders are porous with the pore size increasing with temperature. These experimental findings provide insights for the design of industrial process of hydrogen-based regeneration of iron fuels.

Analysis of the degree of influence of geological and technological factors on the initial flow rates of wells commissioned after their downtime

The results of statistical processing of data from 97 wells put into re-operation, after their long downtime due to flooding, are presented. In which, depending on the geological and physical conditions and the state of development of oil deposits, different results are obtained. With an average initial oil flow rate of 1.12 tons/day in reservoir-vaulted deposits with low-viscosity oil in the Fergana oil and gas region - 0.5 tons/day, in reservoir-arch deposits with high-viscosity oil in the Surkhandarya oil and gas region - 0.97 tons/day, in sub-gas deposits of the Bukhara-Khiva region - 2.5 tons/day. By assessing the informativeness of geological, physical and technological factors using the Kulbak method, the degree of their influence on the initial oil flow rate of wells after their re-commissioning was established. Taking into account the degree of influence of the factors considered, it is recommended to put into re-operation wells located in the arched part of the reservoir, having the highest effective oil-saturated thicknesses, in areas with a low oil recovery factor and a lower degree of reduction in initial reservoir pressure, as well as watered in a short period of operation.

Justification of use of fixed retainers based on the analysis of size of the incisor and canine crowns

Anatomical features of the teeth should be accounted for dental treatment plans. The need for constant monitoring of changes in the dentition system determines the relevance of this research. The study aimed to establish the size of anterior teeth with the help of odontometry. We made bi-layer single stage impressions and cast diagnostic models of the anterior teeth of 50 male and 50 female participants aged 18–24 years. The absolute sizes of crowns of incisors and canines were established. To assess the reduction of lateral incisors, we calculated the interincisor index (Ii) of teeth 22 and 21; sexual dimorphism was determined using the Garn–Lewis formula. It was discovered that there are no differences in the mesiodistal widths of crowns of contralateral teeth on the right and left sides (p > 0.05). The mesiodistal width of crowns of anterior teeth decreases (significant changes) in the following order: maxillary central incisors → maxillary canines → mandibular canines and maxillary lateral incisors → mandibular lateral incisors → mandibular central incisors. The degree of reduction of lateral incisors is low (Ii = 74.9) and more prominent in males than in females. In the examined patients, the greatest mean length of crowns of anterior teeth is that of upper central incisors and lower canines, while upper canines are shorter in length and upper lateral incisors, lower central and lateral incisors have the shortest mean crown length. Males have longer (mean length) crowns of lower canines, upper incisors and canines than females, the difference being significant (p < 0.001). The parameters of the crowns determined in this study showed that they have sufficient height and mesiodistal width, which, together with the low degree of reduction of the lateral incisors, justifies the possibility of direct fabrication of orthodontic fixed retainers. The data can also be used at the stage of dental treatment planning.

Effect of reduction time of functionalized graphene oxide on the morphology and properties of epoxy composite foams

In this study, N-aminoethylpiperazine (AEP)-functionalized and reduced graphene oxide (RGO) with different structures and properties was prepared by simply tuning the reduction time and then its effect on the rheological, curing and foaming behavior of epoxy resin was carefully investigated using the environment-friendly carbamate as a chemical foaming agent. As the reduction time of RGO increased, the reduction degree of RGO first increased and then levelled off but the grafted AEP was little affected by the reduction time. The addition of RGO undergoing long reduction time improved the viscoelasticity of epoxy/reduced graphene oxide (EP/RGO) composites but weakened the interfacial compatibility of RGO and EP. With increasing the reduction time of RGO, the cell size of EP/RGO composite foams decreased and the cell density increased. However, as compared with pure EP foam, the composite foams containing RGO with lower reduction degree had a larger cell size and a lower density. These results were attributed to the complicated effect of RGO, which not only acted as the heterogeneous nucleating and foaming agent but also affected the viscoelasticity of composites. In addition, as the reduction time of RGO increased, the initial thermal decomposition temperature, storage modulus at room temperature, electrical conductivity, thermal conductivity, and compressive properties of EP/RGO composite foams increased while the glass transition temperature remained unchanged. These results were related not only to the intrinsic properties and dispersion of RGO, but also to the density and cell morphology of the composite foams.

A New Methodological Approach on the Characterization of Optimal Charging Rates at the Hydrogen Plasma Smelting Reduction Process Part 2: Results.

To meet the target for anthropogenic greenhouse gas (GHG) reduction, the European steel industry is obliged to reduce its emissions. A possible pathway to reach this requirement is through developments of new technologies for a GHG-free steel production. One of these processes is the hydrogen plasma smelting reduction (HPSR) developed since 1992 at the Chair of Ferrous Metallurgy at the Montanuniversitaet Leoben in Austria. Based on the already available publication of the methodology in this work, potential process parameters were investigated that influence the reduction kinetics during continuous charging to improve the process further. Preliminary tests with different charging rates and plasma gas compositions were carried out to investigate the impacts on the individual steps of the reduction process. In the main experiments, the obtained parameters were used to determine the effect of the pre-reduction degree on the kinetics and the hydrogen conversion. Finally, the preliminary and main trials were statistically evaluated using the program MODDE® 13 Pro to identify the significant influences on reduction time, oxygen removal rate, and hydrogen conversion. High hydrogen utilization degrees could be achieved with high iron ore feeding rates and low hydrogen concentrations in the plasma gas composition. The subsequent low reduction degree and thus a high proportion of oxide melt leads to a high oxygen removal rate in the post-reduction phase and, consequently, short process times. Calculations of the reduction constant showed an average value of 1.13 × 10−5 kg oxygen/m2 s Pa, which is seven times higher than the value given in literature.

Effect of warm-rolling on the strength and ductility of multilayered composite steel

Making composite steel is an effective method to improve the strength and ductility of steel, but it often follows the mixture rule. Further increasing the strength and ductility simultaneously of composite steel is challenging. In this study, warm-rolling was introduced into a multilayered martensite/austenite composite steel after the compositing process. Results revealed that some C atoms diffused from the martensite layer into the neighbouring austenite layer, resulting in a reduced hardness in the martensite layer of common composite steel. Introducing warm-rolling deformation not only hardened each layer effectively, but also clearly improved the ductility of the austenite layer. This facilitated the coordination deformability of the austenite layer and resulted in simultaneous improvements in strength and ductility for warm-rolled composite samples. Better mechanical properties (tensile strength of 1546 MPa and a uniform elongation of 14.9%) were obtained for a sample with a lower degree of reduction (10%). The mechanism leading to improved mechanical properties is analysed in detail in this paper.

The effect of pretreatment on SiO2 for Co-based Fischer-Tropsch synthesis catalysts: a study of the reduction pathway

The reduction pathway of Co catalysts supported on untreated SiO2 along with two pretreated SiO2 support materials was investigated. In situ XRD studies clearly showed the likely reduction pathways of the cobalt oxides on the untreated SiO2, ethylene glycol pretreated SiO2, and annealing pretreated SiO2 supports. Ethylene glycol pretreated SiO2-supported Co (Co/E–SiO2) catalyst showed smaller metal crystallites, highly dispersed Co and high Co(hcp)/Co(fcc) ratio because of the high percentage of non-H-bonded silanols; however, the high percentage of the non-H-bonded silanols created a strong Co-SiO2 interaction which caused a low degree of reduction of CoO resulting in lower FT activity. In contrast, the annealing pretreated SiO2-supported Co (Co/A–SiO2) catalyst did not significantly increase the percentage of non-H-bonded silanols and Co(hcp)/Co(fcc) ratio when compared with Co/E–SiO2, but it exhibited a better catalytic activity during FTS.

The role of defects in the photoconversion of 2-propanol on rutile titania: Operando spectroscopy combined with elementary studies

Previous studies on the reaction chemistry of 2-propanol at rutile powders in liquid phase as well as at TiO2(110) surfaces under UHV conditions, both with low reduction degree, exhibited that partial photo oxidation is observable in the presence of oxygen, however, with low yields. Here, we show that at highly reduced surfaces a partial photo oxidation of 2-propanol is not only possible in the presence of oxygen but also in coadsorption with water or even without coadsorbates below room temperature. Thermally, only the conversion towards propane and propene was observed at temperatures above 550 K. Liquid Phase experiments further showed that the coadsorbate influences the acetone yield of the partial photo oxidation. While in the presence of oxygen an increasing acetone conversion was observed, the acetone yield is reduced in the presence of water in accordance with the hypothesis of an active site blocking by water.

Effect of binders on reduction degree of iron ore pellets

Bentonite is the most preferred silicate-based binder in iron ore pelletizing. However, it is considered an impurity due to its high SiO2 and Al2O3 content. The iron-making economy is adversely affected by the addition of bentonite or other silicate-based binders. In recent years, impurity-free binders have been tested to replace bentonite or to lower the bentonite dosage. The use of polyacrylamide polymer as a binder is tested in this work for that purpose. The performances of the tested binder on pellet qualities: morphology, chemical contents, reducibility, and swelling index have been compared with the performances of reference bentonite binder. A lower reduction degree and swelling was obtained for pellets using bentonite as binder compare with the one using Polycryamide binder.

CO2 mobility control improvement using N2-foam at high pressure and high temperature conditions

The high mobility of CO2 in porous media is an issue in most subsurface CO2 projects worldwide, demonstrated by uncontrolled and rapid migration through the reservoir, early well breakthroughs and poor sweep efficiency. Improved mobility control of CO2 is needed to accelerate and improve the value-creation from subsurface CO2 projects, both in terms of energy produced and volumes of CO2 stored. Field-proven conformance and mobility control techniques, such as foam, provide a cost-effective and sustainable alternative to overcome geological and process constraints observed with CO2 flow in reservoirs.In this laboratory study, we have investigated CO2 mobility control by foam in sandstone core samples at typical North Sea reservoir conditions, 220 barg and 100°C, respectively. Two important aspects related to any field application of foam have been evaluated and discussed: I) Can strong CO2-foams be generated at reservoir conditions using AOS surfactant? If not, II) can relatively simple modifications to the foam system be made to improve foam properties and CO2 mobility control?Our results show that only high-mobility CO2-foams with low degree of CO2 mobility reduction are obtained at 220 barg and 100°C. An easy way to improve the foam properties at reservoir conditions is suggested by changing the gas-phase in foam to nitrogen (N2). The N2-foams display improved foam generation performance, larger mobility control in terms of mobility reduction factors (MRF) and ability to block subsequent CO2 injection.An alternative strategy for applying foam for CO2 conformance and mobility control in subsurface CO2 projects, which emerges from this study, is to initiate the foam treatment with nitrogen followed by subsequent CO2 injection to change the main direction of CO2 flow to enhance the displacement area or reduce uncontrolled CO2 production between the injecting and producing wells (as illustrated in the graphical abstract). The possible mechanisms explaining the observed differences in foam properties using CO2 versus N2, including implications that could be helpful for future studies and CO2 field applications are discussed further in more detail.The efficiency and limitations of miscible CO2 flooding to recover oil and simultaneously store CO2 after extensive water flooding are also demonstrated in this article, which are relevant to enhanced oil recovery (EOR) and subsequent CO2 storage applications, known as the Carbon Capture Utilization and Storage (CCUS).

Carbon Emissions in the Xinjiang Production and Construction Corps and Driving Factors

Xinjiang production and Construction Corps (XPCC) is an important provincial administration in China and vigorously promotes the construction of industrialization. However, there has been little research on its emissions. This study first established the 1998-2018 XPCC subsectoral carbon emission inventory based on the Intergovernmental Panel on Climate Change (IPCC) carbon emission inventory method and adopted the logarithmic mean Divisia indexmethod (LMDI) model to analyze the driving factors. The results revealed that from 1998 to 2018, the total carbon emissions in the XPCC increased from 6.11 Mt CO2 in 1998 to 115.71 Mt CO2 in 2018. For the energy structure, raw coal, coke and industrial processes were the main contributors to carbon emissions. For industrial structure, the main emission sectors were the production and supply of electric power, steam and hot water, petroleum processing and coking, raw chemical materials and chemical products, and smelting and pressing of nonferrous metals. In addition, the economic effect was the leading factor promoting the growth of the corps carbon emissions, followed by technical and population effects. The energy structure effect was the only factor yielding a low emission reduction degree. This research provides policy recommendations for the XPCC to formulate effective carbon emission reduction measures, which is conducive to the construction of a low-carbon society. Moreover, it is of guiding significance for the development of carbon emission reduction actions for the enterprises under the corps and provides a reference value for other provincial regions.

The Immobilization of Pd(II) on Porous Organic Polymers for Semihydrogenation of Terminal Alkynes.

Highly selective catalytic hydrogenation of alkynes to alkenes is a highly important reaction owing to its industrial and commercial application. Specifically, semihydrogenation of terminal alkynes has been more challenging than internal alkenes even using Lindlar catalysts. Also, the high reduction degree state metal-supported catalysts like Pd0/C, Pt0/C, and Ru0/C have been well-known to be used widely in hydrogenation due to their super activity. However, charcoal can absorb a large amount of water; Pd/C with 50% water is convenient on a large-scale synthesis. Charcoal generally bears oxygen groups on its surface, which are responsible for low selectivity and undesired products. Even typically, only 10-60% of the Pd metal atoms are exposed, they still suffer from poor stability in acids owing to leaching. Herein, we intend to design active and stable metal catalysts with features as the following to avoid leaching: having strong interaction with the support and coordinatively unsaturated metal sites or low valence state metals physically isolated from the acid environment. Herein, a highly efficient semihydrogenation of terminal alkynes to produce alkenes has been realized using a heterogeneous Pd(II)/POP-GIEC catalyst, imine-linked, crystalline, and porous organic polymer supporter modified by coordination of Pd(OAc)2 to its walls under mild conditions. Surprisingly, for the first time, modified POP-supported low reduction degree PdII catalysts were synthesized efficiently, and they were successfully used in semihydrogenation of terminal alkynes. The substrate scope was studied and included both unfunctionalized as well as functionalized substituents on the para, ortho, and meta position of aromatic alkynes. The substrate having a substituent with the functionality of fluoro protected at the meta position was semihydrogenated with a high alkyne conversion of 100% and olefin selectivity (up to 99%).

Energy storage of supercapacitor electrodes on carbon cloth enhanced by graphene oxide aerogel reducing conditions

Abstract Supercapacitor performance can be enhanced when the specific capacitance of its electrodes is increased by the electrode fabrication parameters, composition, and structure. The electrode application range can be enlarged from supercapacitors to tribo- or piezo- generators as a part of self-charging power cell for one-step energy conversion and storage by the use of flexible kind of support for the active material such as conducting textile. Here, we use suspended mixture of graphene oxide (GO) aerogel, carbon nanotubes and poly(vinylidene fluoride-co-hexafluoropropylene) for screen printing of flexible electrodes on carbon cloth. Two kinds of reduced graphene oxide (rGO) aerogels are prepared using freeze drying of GO solution with further reduction at 180 °C in vacuum and at 700 °C in Ar, respectively. The composite electrodes with rGO annealed at 180 °C show higher specific capacitance likely because of better homogeneity and surface wettability and despite lower reduction degree and electrical conductivity compared to that of the electrodes with rGO heat treated at 700 °C. The highest specific capacitance values of 129, 116, 110, 104 F g − 1 at 0.1, 0.2, 0.5 and 1 A g − 1, respectively, are obtained for the flexible composite electrode on the carbon cloth with rGO aerogel annealed at 180 °C. Moreover, the rGO-aerogel-based electrode shows high rate capability because it can retain 80% of capacitance as the discharge current is raised from 0.1 to 1 A g − 1. This stable capacitive performance of the prepared flexible electrodes demonstrates their high potential for wearable electronics and self-powered devices.

Quantifying microbial metabolism in soils using calorespirometry — A bioenergetics perspective

Microbial carbon use efficiency (CUE) measures the partitioning between anabolic and catabolic processes. While most work on CUE has been based on carbon (C) mass flows, the roles of organic C energy contents and microbial energy demand on CUE have been rarely considered. Thus, a bioenergetics perspective could provide new insights on how microorganisms utilize C and ultimately allow evaluating their role in C stabilization in soils. Recently, the calorespirometric ratio (CR)—the ratio of heat dissipation and respiration—has been used to characterize the efficiency of microbial growth in soils. Here, we formulate a coupled mass and energy balance model for microbial growth and provide a generalized relationship between CUE and CR. In the model, we consider two types of organic C in soils: an added substrate (e.g., glucose) and the native soil organic matter (SOM), to also account for priming effects. Furthermore, we consider both aerobic and fermentation metabolic pathways. We use this model as a framework to generalize previous formulations and generate hypotheses on the expected variations in CR as a function of substrate quality, metabolic pathways, and microbial traits (specifically CUE). In turn, the same equations can be used to estimate CUE from measured CR.Our results confirm previous findings on CR and show that without microbial growth, CR depends only on the rates of the different metabolic pathways, while CR is also a function of the growth yields for these metabolic pathways when microbial growth occurs. Under strictly aerobic conditions, CUE increases with increasing CR for substrates with a higher degree of reduction than that of the microbial biomass, while CUE decreases with increasing CR for substrates with a lower degree of reduction than the microbial biomass. When aerobic reactions and fermentation occur simultaneously, the relation between CUE and CR is mediated by (i) the degree of reduction of the substrates, (ii) the rates and growth yields of all metabolic pathways, and (iii) the contribution of SOM priming to microbial growth. Using the proposed framework, calorespirometry can be used to evaluate CUE and the role of different metabolic pathways in soil systems.

Controlled synthesis of reduced graphene oxide-carbon nanotube hybrids and their aqueous behavior

This paper reports the controlled synthesis of reduced graphene oxide-carbon nanotube (rGO-CNT) hybrids and their aqueous behavior. The CNTs were suspended in an aqueous dispersion of GO, and the GO-CNT hybrids were reduced in situ in a controlled fashion using nascent hydrogen. Several hybrids with oxygen content ranging from 26 to 2% were synthesized. The properties of the hybrids with low degree of reduction were closer to GO while those with high degree of reduction were closer to CNTs. Solubility, dispersibility, hydrophobicity, critical coagulation concentration (CCC value), and Zeta potential of the hybrids were studied and compared. Solubility of GO-CNT hybrid decreased from 6.2 to ~ 0 μg/ml after reducing oxygen content to 2%. Dispersibility of hybrids also decreased from 7.1 to 0.5 μg/ml after GO reduction. CCC value of hybrids in the presence of NaCl decreased from 16 in unreduced GO-CNT hybrid to 6 for one containing 7% oxygen, and equivalent decrease in the presence of MgCl2 was from 3 to 1. Additionally, as expected, the hydrophobicity of hybrids increased on reduction and the hydrophobicity index increased from − 3.2 to 7.4% as oxygen concentration decreased from 26 to 2%.

Cobalt-based Fischer–Tropsch catalysts supported on different types of N-doped carbon nanotubes

N-doped nanocarbons are promising materials for metal-free and supported catalysts. Three types of N-doped carbon nanotubes (N-CNTs) were synthesized by chemical vapor deposition (CVD), by oxidation of the CVD produced N-CNTs with nitric acid, and by post-doping of oxidized undoped CNTs with ammonia. Cobalt catalysts with 20[Formula: see text]wt.% loading supported on N-CNTs were tested in the Fischer–Tropsch synthesis. Oxidized N-CNTs containing pyridone groups demonstrated the best stabilization of cobalt nanoparticles. The catalyst on this support showed the highest selectivity towards [Formula: see text] hydrocarbons. The performance of the catalyst supported on CVD N-CNTs was the worst because of the large variation in cobalt particle size and low reduction degree. The catalysts supported on post-doped CNTs demonstrated the best activity, but high methane selectivity because of the low Co particle size ([Formula: see text][Formula: see text]nm).