Thermal Extraction Technique Research Articles

Sustainable biorefining: Hydrothermal liquefaction of diatom biomass for bio-crude and nano-biosilica recovery

Diatom, a unique species of microalgae is a highly promising resource for the production of valuable bio-crude and silica nanomaterial. However, the complex nature of diatom cell structure presents significant downstream processing challenges and leads to inefficient bio-product recovery. To overcome this challenge, this study aimed to develop a one-step approach for the valorization of Denticula sp. dominated diatom consortium using hydrothermal liquefaction (HTL) process with the recovery of three major products. The first output, referred to as biocrude, constituted 22% of the total yield, consisting of 9.5% unbound bio-crude and 12.5% cell wall-bound organic fraction. The bio-crude consisted primarily of oxidized and desirable organic compounds like alcohols (24.4%), long-chain saturated hydrocarbons (23.6%), and esters (17.6%), with only a few undesirable nitrogen-containing compounds (18.9%). The second resultant product comprised nanoporous bio-silica structures, yielding 56%. These silica structures exhibited enhanced quality in comparison to the conventional thermal extraction technique employed for their retrieval and were found to be three-dimensional, highly porous, intact silica structures with low trace elements and a high surface area (53.7 m2 g−1). The third acquired product, the aqueous fraction, was observed to possess elevated levels of nitrate-nitrogen (440 mg L−1) and total dissolved phosphate (975 mg L−1). Overall, the study highlights the potential of HTL as an efficient diatom downstream processing method that allows for the complete valorization of intermediates, resulting in a sustainable biomass conversion and product recovery technology.

Effect of extraction methods on the chemical, structural, and rheological attributes of fructan derived from Arctium lappa L. roots

The focus of this study was the evaluation of how extraction techniques impact the chemical, structural, and rheological attributes of fructans extracted from Arctium lappa L. roots. Three distinct extraction procedures were used, utilizing water as solvent, infusion extraction conducted at ambient temperature (25 °C for 5 min), thermal extraction employing reflux (100 °C for 2 h), and ultrasound-assisted extraction (50 °C for 1.38 h with a 158 W output). Chemical characterization by Nuclear Magnetic Resonance (NMR) and colorimetric analyses revealed the obtaining of inulin-type fructans (yield 83 %). The degree of polymerization (DP) was found to be the lowest for ultrasound-assisted extraction (14.38), followed by the room-temperature (20.41) and thermal (21.14) extraction techniques. None of the extraction techniques appeared to modify the molecular structure of the isolated compounds. In X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses, distinct crystallization patterns were observed for the room-temperature and thermal extraction techniques, though all fractions consistently exhibited characteristic bands of inulin-type fructan. Rheological assessments indicated a viscoelastic nature of the fractions, with those extracted thermally demonstrating a greater viscosity. This study shows that the choice of extraction method can influence the structural characteristics of inulin-type fructans derived from the burdock root.

Artificial Maturation of Iron- and Sulfur-Rich Mars Analogues: Implications for the Diagenetic Stability of Biopolymers and Their Detection with Pyrolysis-Gas Chromatography-Mass Spectrometry.

Acidic iron- and sulfur-rich streams are appropriate analogues for the late Noachian and early Hesperian periods of martian history, when Mars exhibited extensive habitable environments. Any past life on Mars may have left behind diagnostic evidence of life that could be detected at the present day. For effective preservation, these remains must have avoided the harsh radiation flux at the martian surface, survived geological storage for billions of years, and remained detectable within their geochemical environment by analytical instrument suites used on Mars today, such as thermal extraction techniques.We investigated the detectability of organic matter within sulfur stream sediments that had been subjected to artificial maturation by hydrous pyrolysis. After maturation, the samples were analyzed by pyrolysis–gas chromatography–mass spectrometry (py-GC-MS) to determine whether organic matter could be detected with this commonly used technique. We find that macromolecular organic matter can survive the artificial maturation process in the presence of iron- and sulfur-rich minerals but cannot be unambiguously distinguished from abiotic organic matter. However, if jarosite and goethite are present in the sulfur stream environment, they interfere with the py-GC-MS detection of organic compounds in these samples. Clay reduces the obfuscating effect of the oxidizing minerals by providing nondeleterious adsorption sites. We also find that after a simple alkali and acid leaching process that removes oxidizing minerals such as iron sulfates, oxides, and oxyhydroxides, the sulfur stream samples exhibit much greater organic responses during py-GC-MS in terms of both abundance and diversity of organic compounds, such as the detection of hopanes in all leached samples.Our results suggest that insoluble organic matter can be preserved over billions of years of geological storage while still retaining diagnostic organic information, but sample selection strategies must either avoid jarosite- and goethite-rich outcrops or conduct preparative chemistry steps to remove these oxidants prior to analysis by thermal extraction techniques.

Effect of high-temperature extracted plant material fume against southern cowpea weevil (Callosobruchus chinensis L.) (Coleoptera: Bruchidae) as a non-chemical novel fumigation technique

BackgroundFumes from high-temperature heated plant leaves containing volatile phytochemicals generated from Lantana camara, Cinnamomum zeylanicum, Azadirachta indica and Ocimum sanctum were tested for their insecticidal activity against adult southern cowpea weevil (Callosobruchus chinensis L.) and their F1 progeny production/emergence. Volatile phytochemicals containing fume was generated using a flameless dry heat extraction method similar to pyrolysis combustion without air supplement at 180 ± 5 °C. Insect mortalities were assessed up to 72 h after exposure to the different treatments of fumigation by plant-fume and control.ResultsAll volatile plant-fume samples contained average of 16.3 ± 1.5% O2 and 5.8 ± 0.5% CO2 in the test jars. The F1 progeny emergence was estimated 30 days after treatment. After 36 h of exposure, L. camara showed the highest toxicity against C. chinensis, followed by O. sanctum, A. indica and C. zeylanicum, with LT50 values of 7.3, 9.4, 14.7 and 20.6 h, respectively. The volatile phytochemical containing plant-fume generated by A. indica and C. zeylanicum produced LT99 values that were not significantly different (P > 0.05) from each other. The F1 adult emergence from treated mungbean (Vigna radiata L.) samples was significantly inhibited by L. camara and A. indica volatile plant-fume compared to C. zeylanicum fume. However, plant-fume generated from all four plants exhibited effective direct toxicity and F1 progeny inhibition of more than 86%.ConclusionFrom the study, it can be concluded that volatile plant-fume treatment was highly lethal to C. chinensis and significantly reduced F1 progeny emergence. Therefore, phytochemicals obtained from thermal extraction technique can be used as an alternative technique to chemical fumigation of stored mungbean.

Cost-effective FTIR and 1H NMR spectrometry used to screen valuable molecules extracted from selected West African trees by a sustainable biochar process

This study focused on wood extractives by a slow pyrolysis thermal extraction technique and screening of potentially valuable compounds from three African trees: Lophira lanceolata Tiegh. ex Keay., Dialium guineense Willd. and Afzelia africana Sm. The primary objective of the thermal treatment was biochar production but also liquids were collected and analyzed. Raw materials were cut into sizes of about 25 cm in length and then processed with slow pyrolysis from 20 °C up to 400 °C; the slow pyrolysis process included two stages, drying and pyrolysis. Five end-point temperatures were used in the range of 250 °C–400 °C. Raw distillates were collected at three temperatures (120 °C, 60 °C and 25 °C) and their composition screened by either cost-effective FTIR or benchtop 80 MHz 1H NMR methods. HR-NMR and 2D GC–MS were used to confirm some findings. Results from the drying stage indicated that all distillates contained mostly water >90%, acetic acid, methanol and some other compounds at very low levels. The percentages of acetic acid were 3.5% for L. lanceolate, 2.8% for D. guineensis and 3.8% for A. africana (% with respect to the identified peaks). Results from the pyrolysis stage revealed the presence of bioactive compounds such as ketones, methanol, hydrocarbons, acetic acid, esters, alkenes and phenolic compounds at higher quantities than in the drying stage. The quantity of phenols in certain runs and distillate fractions using NMR was 1%–20% for L. lanceolata, 7–17% for D. guineensis and 10%–17% for A. africana (% with respect to the composition of the identified peaks). The percentage of hydrocarbons was 1%–48% for L. lanceolata, 1%–34% for D. guineensis and 2%–33% for A. africana. The percentage of ketones was 7%–19% for L. lanceolate, 4%–27% for D. guineensis and 19%–22% for A. africana. In general, the results indicated the presence of potential valuable compounds at relatively high concentrations. By optimizing the slow pyrolysis process parameters, it is possible to collect distillates with high concentrations of valuable biomolecules.

Esophageal cooling for protection during left atrial ablation: a systematic review and meta-analysis

PurposeThermal damage to the esophagus is a risk from radiofrequency (RF) ablation of the left atrium for the treatment of atrial fibrillation (AF). The most extreme type of thermal injury results in atrio-esophageal fistula (AEF) and a correspondingly high mortality rate. Various strategies for reducing esophageal injury have been developed, including power reduction, esophageal deviation, and esophageal cooling. One method of esophageal cooling involves the direct instillation of cold water or saline into the esophagus during RF ablation. Although this method provides limited heat-extraction capacity, studies of it have suggested potential benefit. We sought to perform a meta-analysis of published studies evaluating the use of esophageal cooling via direct liquid instillation for the reduction of thermal injury during RF ablation.MethodsWe searched PubMed for studies that used esophageal cooling to protect the esophagus from thermal injury during RF ablation. We then performed a meta-analysis using a random effects model to calculate estimated effect size with 95% confidence intervals, with an outcome of esophageal lesions stratified by severity, as determined by post-procedure endoscopy.ResultsA total of 9 studies were identified and reviewed. After excluding preclinical and mathematical model studies, 3 were included in the meta-analysis, totaling 494 patients. Esophageal cooling showed a tendency to shift lesion severity downward, such that total lesions did not show a statistically significant change (OR 0.6, 95% CI 0.15 to 2.38). For high-grade lesions, a significant OR of 0.39 (95% CI 0.17 to 0.89) in favor of esophageal cooling was found, suggesting that esophageal cooling, even with a low-capacity thermal extraction technique, reduces the severity of lesions resulting from RF ablation.ConclusionsEsophageal cooling reduces the severity of the lesions that may result from RF ablation, even when relatively low heat extraction methods are used, such as the direct instillation of small volumes of cold liquid. Further investigation of this approach is warranted, particularly with higher heat extraction capacity techniques.

Effect of Hydration State of Martian Perchlorate Salts on Their Decomposition Temperatures During Thermal Extraction

AbstractThree Mars missions have analyzed the composition of surface samples using thermal extraction techniques. The temperatures of decomposition have been used as diagnostic information for the materials present. One compound of great current interest is perchlorate, a relatively recently discovered component of Mars' surface geochemistry that leads to deleterious effects on organic matter during thermal extraction. Knowledge of the thermal decomposition behavior of perchlorate salts is essential for mineral identification and possible avoidance of confounding interactions with organic matter. We have performed a series of experiments which reveal that the hydration state of magnesium perchlorate has a significant effect on decomposition temperature, with differing temperature releases of oxygen corresponding to different perchlorate hydration states (peak of O2 release shifts from 500 to 600°C as the proportion of the tetrahydrate form in the sample increases). Changes in crystallinity/crystal size may also have a secondary effect on the temperature of decomposition, and although these surface effects appear to be minor for our samples, further investigation may be warranted. A less than full appreciation of the hydration state of perchlorate salts during thermal extraction analyses could lead to misidentification of the number and the nature of perchlorate phases present.

Apatite Wollastonite-Reinforced Hydroxyapatite Biocomposites

The paper is focused on the reinforcement of hydroxyapatite (HA) by apatite wollastonite (AW) because of its aptitude for combining biocompability with mechanical properties superior to those of the bone. HA powders were produced by thermal extraction technique involving calcination from natural source. HA-AWP biocomposites containing from 0 to 20 wt.% of AW in particulate form were prepared starting with wet ball milling during 24 h, followed by powder metallurgical processes using HA powders calcined at 800 ◦C, followed by compaction by cold pressing and by cold isostatical pressing at 250 MPa and subsequent sintering at 1100–1300 ◦C. The phases and compositions in the resulting products were identified by XRD and XRF. Reinforcement particle distribution were investigated on polished surfaces of the sintered samples by SEM analysis and by optical microscopy. Mechanical properties of the sintered samples was evaluated via Micro Vickers hardness testing.

Application of hybrid microwave thermal extraction techniques for mulberry root bark

The main focus of this paper is the extraction of compounds from the mulberry root bark using a hybrid microwave thermal process. The shearing mechanism and an integrated circulation system, which increases the rate of contact between the solvent and extractive, are studied. The results are analyzed by the Taguchi method and verified by high performance liquid chromatography. Furthermore, the optimal operating parameters of the extraction of mulberry root bark are discussed. The results show that hybrid microwave thermal extraction can successfully extract the active ingredients from mulberry root bark. This is a reliable basis for further researches.

Self-heating effects in SOI MOSFETs and their measurement by small signal conductance techniques

Self-heating is an important issue for SOI CMOS, and hence, so is its characterization and modeling. This paper sets out how the critical parameters for modeling, i.e., thermal resistance and thermal time-constants, may be obtained using purely electrical measurements on standard MOS devices. A summary of the circuit level issues is presented, and the physical effects contributing to thermally related MOSFET behavior are discussed. A new thermal extraction technique is presented, based on an analytically derived expression for the electro-thermal drain conductance in saturation. Uniquely, standard MOSFET structures can be used, eliminating errors due to additional heat flow through special layouts. The conductance technique is tested experimentally and results are shown to be in excellent agreement with thermal resistance values obtained from noise thermometry and gate resistance measurements using identical devices. It is demonstrated that the conductance technique can be used confidently over a wide range of bias conditions, with both fully and partially depleted devices.

Tritium Assay of Li2O in the LBM/LOTUS Experiments

The Lithium Blanket Module (LBM) is an assembly of over 20,000 cylindrical lithium oxide pellets in an array representative of a limited-coverage breeding zone for a toroidal fusion device. A principal objective of the LBM program is to test the ability of advanced neutronics coding to model the tritium breeding characteristics of a fusion device blanket. The LBM has been irradiated at the Ecole Polytechnique Federale de Lausanne (EPFL) LOTUS facility with a 14 MeV point-neutron source. Princeton Plasma Physics Laboratory (PPPL) and EPFL assayed the tritium bred in lithium oxide diagnostic samples placed at various positions in the LBM. PPPL employed a thermal extraction technique while EPFL used a dissolution method. The results form the assay are reported and compared to MCNP Monte Carlo neutronics calculations for the LBM/LOTUS system.