Although there are many studies on the characterization of C in biochar and its C sequestration potential, there is little knowledge on the mineral fraction in biochar and its weathering. The latter, ...however, can have powerful implications on nutrient availability. In the present study, a modified Soxhlet reactor was used to simulate the long-term geochemical weathering of an ash-rich biochar produced from sewage sludge of a non-industrial area in New Zealand. The weathering process took place during a period of 300
h, with and without the addition of humic acid (1.00
g added to 20.00
g of biochar), and the treatments were referred to as treatment BC-HA and BC-B, respectively. Both the leaching kinetics and the transformations within the solid phase were studied. The results revealed that substantial amounts of K (8.5–10.2%) and S (20.2–28.3%) were recovered in the weathering solutions. Noticeable Ca (17.9–20.7%) and P (15.4%) in the solid were released but only a few were recovered in the weathering solutions because of the precipitation. The presence of humic acids increased this dissolution and thus the availability of K, S, Ca, Mg and P, but induced N immobilization. Nitrogen availability was already very low (<1.0% of the total N) due to the probable recalcitrant heterocyclic N structure. The pH of the biochar samples dropped from 8.4 to 7.5; this was mainly attributed to loss of base cations through leaching and probable carbonation of the system. The XPS spectra evidenced the oxidation of C in biochar during the weathering process with the formation of carbonyl and carboxylic functional groups. The results obtained in this study showed some promise for the positive use of modified Soxhlet extractor in simulating the geochemical weathering in ash-rich biochars and providing a better understanding on the kinetics of nutrient release. This will be key information in assessing the added value of biochars as soil amendments.
► Feedstock type and pyrolysis conditions influence the degree of biochar carbonisation. ► Intrinsic lability of biochar revealed via spectroscopic and thermogravimetric analysis. ► Wet oxidation ...provided qualitative and quantitative information on biochar lability. ► C evolved as CO
2 from biochar-amended soil after 110
h was related to carbonisation degree.
Different analytical techniques were used to find the most reliable and economic method for determining the labile fraction of C in biochar. Biochar was produced from pine, poplar and willow (PI, PO and WI, respectively) at two temperatures (400 and 550
°C) and characterised using spectroscopic techniques solid state
13C nuclear magnetic resonance spectroscopy (NMR), molecular markers pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), thermogravimetry (TG), elemental composition and wet oxidation (potassium permanganate and potassium dichromate). Short term incubation (110
h) of an A horizon from an Umbrisol amended with the biochar samples at two doses (7.5 and 15
t
ha
−1) was also carried out to provide supplementary information on the influence of biochar–soil interaction on CO
2 evolution. Spectroscopic analysis demonstrated that the degree of biochar carbonisation was influenced by the type of feedstock and heating conditions and followed the order WI-400
<
PI-400
∼
WI-550
∼
PO-400
<
PO-550
<
PI-550. The thermo-labile fraction of the biochar samples, estimated from TG, ranged between 21% and 49%. The fraction of total C oxidised with potassium permanganate (C
per/C
total) was <50
g
kg
−1 in all cases, whereas potassium dichromate (C
dichro/C
total) oxidation efficiency ranged between 180 and 545
g
kg
−1. For each type of feedstock, the highest values of either chemically or thermally degradable C corresponded to the biochar produced at low temperature. Results indicate that low cost methodologies, such as dichromate oxidation and TG, reflected the degree of biochar carbonisation, and could therefore be used to estimate the labile fraction of C in biochar.
A large number of porous carbon materials with different properties in terms of porosity, surface chemistry and electrical conductivity, were prepared and systematically studied as electric double ...layer capacitors in aqueous medium with H
2SO
4 as electrolyte. The precursors used are an anthracite, general purpose carbon fibres and high performance carbon fibres, which were activated by KOH, NaOH, CO
2 and steam at different conditions. Among all of them, an activated anthracite with a BET surface area close to 1500
m
2/g, presents the best performance, reaching a value of 320
F/g, using a three-electrode system. The results obtained for all the samples, agree with the well-known relationship between capacitance and porosity, and show that the CO-type oxygen groups have a positive contribution to the capacitance. A very good correlation between the specific capacitance and this type of oxygen groups has been found.
Purpose
Compartment syndrome is a surgical emergency that can occur in any part of the body and can cause cell necrosis when maintained over time. The resulting defects can affect the nerves, muscle ...cells, bone tissue, and other connective tissues inside the compartment, and fasciotomy has to be performed. The anatomical and histological characteristics of the leg make acute, chronic, and exertional compartment syndrome more likely in this limb. For these reasons, knowledge of the ultrasound, anatomical, and histological features of the crural fascia can help in the treatment of leg compartment syndrome.
Methods
Twenty-one cryopreserved lower limbs from adult cadavers and from one 29-week-old fetus were obtained from the dissection room. They were examined by ultrasound and a subsequent anatomical dissection and microscopy to study the crural fascia and its relationship with the different muscles. Anthropometric measurements were taken of the distances from the head of the fibula and lateral malleolus to the origin of the tibialis anterior muscle in the crural fascia, the exit of the superficial fibular nerve, and the fascia covering the deep posterior muscles of the leg.
Results
The crural fascia has very important clinical relationships, which can be identified by ultrasound, as the origin of the tibialis anterior muscle at 16.25 cm from the head of the fibula and the exit of the superficial fibular nerve that crosses this fascia at 21.25 cm from the head of the fibula. Furthermore, the presence of a septum that fixes the deep posterior muscles of the leg and the vessels and nerve can be seen by ultrasound and can explain the possible development of a posterior compartmental syndrome of the leg. Awareness of these features will help to keep these structures safe during the surgical treatment of compartment syndrome.
Conclusion
The ultrasound study allows identification of anatomical structures in the leg and, thus, avoids damage to them during surgery for compartmental syndromes.
A concept for thermal energy storage (TES) in concrete as solid media for sensible heat storage is proposed to improve the cost and efficiency of solar thermal electricity (STE) plants. Mortar and ...concrete mixes were designed with calcium alumina cement (CAC) blended with blast furnace slag (BFS), using aggregates of different sources and size for stability performance after long term at high temperature. Seventy-five thermal cycles of 24h length, within the temperature range 290°C to 550°C, have been used to simulate the expected operating conditions of TES. The dehydration processes at microstructural level have been evaluated and correlated with mechanical properties. Dehydration processes and consecutive heat/cool cycles induce changes in concrete at micro- and macro-level. The stabilization of damage with the charge/discharge heat cycles for thermal fatigue depends significantly on the aggregate type used. CAC is a suitable binder to use in thermal energy storage systems able to maintain its properties under repetitive heat cycles.
•Design of an efficient thermal concrete to be used as solid thermal energy storage system in solar thermal energy plants.•Develop and characterize concrete mixes based on high alumina cement blended with blast furnace slag and suitable aggregate grading to endure long periods at high temperature.•Thermal fatigue resistance due to heat cycles effect, from 290°C to 550°C, and characterization of damage evolution at micro- and macro-level.
As a part of understanding of iron and steel passivity, the dissolution rate of magnetite has been studied in anaerobic borate buffer at 25 °C between −0.5 and −0.75 V/SHE. The dissolution rates have ...been estimated from weight loss measurements. Linear weight losses in time have been obtained corresponding to constant dissolution rates. Nevertheless the rates depended on potential according to a Butler-Volmer law. Another Butler-Volmer law has been obtained for the steady-state cathodic current density flowing through the magnetite layer and ending by the proton reduction step. For both, the quantitative Butler-Volmer parameters have been estimated from the experiments. The cathodic feature of the electrochemical dissolution rate for magnetite was confirmed but the electron balance analysis has shown that this dissolution did not involved electrons as mentioned in the literature. One possible mechanism is proposed in which the kinetics of the proton reduction step tunes the outer voltage drop at the magnetite-solution interface and this voltage drop steers the kinetics of the dissolution rate.
Beach handball is a spectacular new team sport; however, scientific knowledge about the demands in beach handball is very low. Consequently, the aim of this study was to analyze the physical demands ...of elite beach handball players by means of time-motion analysis with GPS technology and physiological response with Heart Rate (HR). Both male (n = 12) and female (n = 12) players from the Spanish Beach Handball National Team were recruited for this study. The sample consisted in four matches of two 10-min periods each. Time-motion analysis was performed through GPS devices (SPI Pro X, 15 Hz, GPSports) with synchronized HR monitoring (Polar Electro, Finland). All parameters were recorded for matches and halves to express overall and time-dependent physical and physiological responses. Total match distance covered by male and female players were 1234.7 ± 192 m and 1118.2 ± 221.8 m, respectively. Female players covered more total distance (p = 0.049, ES = 0.79) and distance walking (p < 0.001, ES = 2.04) in the first half, whereas they covered more distance standing (p = 0.008, ES = 1.05) in the second half at a higher average speed (p < 0.001, ES = 2.28). The number of accelerations distributed over low-, moderate- and high-intensity categories were 43.2 ± 11.6, 9.4 ± 4.9; 0.8 ± 0.9 m/s
for male players, and 40.3 ± 12.7, 4.3 ± 3.0; 0.1 ± 0.3 m/s
for female players; equivalent to one body acceleration every 23 s and 27 s, respectively. Finally, male and female players obtained a maximum/mean HR of 173 ± 13 / 137 ± 12 bpm, and 177 ± 13 / 138 ± 18 bpm, with 20.3% and 29.2% of the total time in the anaerobic zone (81 - 90% HRmax), respectively. These results demonstrated that beach handball is a demanding sport, with numerous moderate-to-high intensity displacements, distributed intermittently throughout the game: long periods of low intensity activity interspersed by short bursts of high intensity.
Purpose
Acute compartment syndrome is defined as a limb-threatening condition caused by bleeding or oedema in a closed muscle compartment surrounded by fascia or bone. It is most commonly encountered ...in the forearm, which has three compartments: posterior, anterior and lateral. These are surrounded and closed in by the antebrachial fascia, formed by dense connective tissue that facilities their study on ultrasound and is key to fasciotomy treatment. The purpose of this study was to broaden existing ultrasound, anatomical and histological knowledge of the fascia of the forearm to facilitate their identification on ultrasound, with possible clinical and therapeutic applications.
Methods
The study was performed in 50 cryopreserved upper limbs from adult cadavers from the dissection room of the Faculty of Medicine and Health Sciences. They were examined on ultrasound and subsequent anatomical dissection and microscopy to study the fascia and its relationship with different muscles of the forearm compartments.
Results
Distinct anatomical relationships were observed on ultrasound and dissection between the fascia and the extensor carpi ulnaris, extensor digiti minimi, and anconeus muscle in the posterior compartment, and the flexor carpi radialis and flexor carpi ulnaris in the anterior compartment. They were isolated by the antebrachial fascia and had distinct relationships with the neurovascular structures.
Conclusion
These results demonstrate that high-definition ultrasound enables us to locate the antebrachial fascia and particular muscles with a distinct relationship with neurovascular structures. This helps better identify these structures, facilitating diagnosis of any pathology in the area, with potential therapeutic and clinical applications.
Vitrification of solid technological waste is currently under investigation. For this type of waste made up of metals, minerals, and organic matters, formulation studies were carried out in the NCAS ...(Na2O–CaO–Al2O3–SiO2) system in order to define a vitrifying additive to treat the entire waste deposit, while maximizing the waste loading. Main challenge related to this type of waste comes from the presence of alumina in very large quantities in the glass/glass–ceramics melt, enhancing the risk of melt solidification due to a fast and massive crystallization. Melt lock‐up can potentially occur at the operating temperature envisaged for the process (1400°C) and is prohibitive because it would lead to a premature stoppage of the process. The results obtained from casting tests, rheological experiments, and thermodynamic modeling enabled to provide an accurate estimation of the risk of melt lock‐up for NCAS compositions. It was highlighted that the composition had a major influence on the temperature at which massive crystallization might occur. From all the results obtained, the maximum Al2O3 content that could be incorporated in the final material was determined to be close to 50 wt%. The composition of a vitrifying additive was also statistically designed to treat the technological waste of interest.
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