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1.
J Endovasc Ther ; : 15266028241232915, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38414229

RESUMO

OBJECTIVE: Endovascular aneurysm repair (EVAR) has been used worldwide to treat abdominal aortic aneurysms (AAAs). Outcomes after EVAR within and outside the instruction for use (IFU) remain controversial. We analyzed long-term outcomes of EVAR within-the-IFU compared with that outside-the-IFU and baseline clinical/anatomical characteristics that influence outcomes of EVAR. METHODS: The study included 546 patients who underwent EVAR for infrarenal AAA from 1997 to 2021 at 2 Korean medical centers. The primary endpoint was graft-related adverse events (GRAEs), including type 1 or 3 endoleak, reintervention (included open conversion), aneurysm sac enlargement, aneurysm-related mortality (ARM), rupture, stent-graft migration, and stent thrombotic occlusion. RESULTS: The patients who underwent EVAR outside the IFU were 287 (52.6%). A neck angle of >60° was most common outside the IFU criteria (n=146, 50.9%). This study revealed that patients outside the IFU had a higher rate of GRAEs compared with patients within the IFU (hazard ratio [HR]: 1.879; 95% confidence interval [CI]: 1.045-2.386). A neck angle of >60° was a significant risk factor for GRAEs (adjusted HR: 2.229; 95% CI: 1.418-3.503), type 1 or 3 endoleak (adjusted HR: 2.640; 95% CI: 1.343-5.189), and reintervention (adjusted HR: 1.891; 95% CI: 1.055-3.388). CONCLUSIONS: Our study revealed EVAR with outside the IFU was associated with increased GRAEs, mainly attributed to endoleak and ARM, compared with EVAR with within the IFU. In addition, severe neck angulation was an independent risk factor for GRAEs, type 1 or 3 endoleak, and reintervention. CLINICAL IMPACT: Our study revealed endovascular aneurysm repair (EVAR) with outside-the-instruction for use (IFU) was associated with increased graft-related adverse events (GRAEs) compared with EVAR with within-the-IFU. In the low-risk population, the incidence of GRAEs and Aneurysm related mortality were higher in the outside-the-IFU group rather than within-the-IFU group. In addition, severe neck angulation was an independent risk factor for GRAEs, type 1 or 3 endoleak and reintervention.

2.
Medicina (Kaunas) ; 59(9)2023 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-37763768

RESUMO

Background and Objectives: Polymer-free ultrathin strut sirolimus- and probucol-eluting stents (PF-SES) are recognized as safe and effective in diverse patient populations, although the implications of post-dilation during stent implantation remain underexamined. Materials and Methods: In this study, patients implanted with PF-SES at Gachon University Gil Medical Center between December 2014 and February 2018 were evaluated. Major adverse cardiovascular events (MACE), encompassing nonfatal myocardial infarction (MI), nonfatal stroke, and cardiovascular death were identified as primary outcomes, with secondary outcomes including target vessel revascularization (TVR), target lesion revascularization (TLR), and in-stent restenosis (ISR). Results: Of the 384 initial patients, 299 were considered eligible for analysis. The groups, delineated by those undergoing post-dilation (143 patients) and those not (156 patients), exhibited comparable rates of primary outcomes [hazard ratio (HR), 2.17; 95% confidence interval (CI), 0.40 to 11.87; p = 0.37]. The outcomes remained consistent irrespective of the post-dilation status and were similarly unaffected in multivariate analyses (HR, 2.90; 95% CI, 0.52 to 16.34; p = 0.227). Conclusions: These results suggest that the clinical outcomes of patients with post-dilation were similar to that of those without post-dilation in those with the polymer-free sirolimus- and probucol-eluting stents.

3.
Bioresour Technol ; 394: 130185, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38072073

RESUMO

Currently, humankind is facing a serious environmental and climate crisis, which has accelerated the research on producing bioenergy from waste biomass as a carbon-neutral feedstock. In this study, the aim was to develop an upcycling strategy for waste biomass to solid-type biofuel conversion for power generation. Various types of waste biomass (i.e., waste wood after lumbering, sawdust-type mushroom waste wood, kudzu vine, and empty fruit bunches from palm) were used as sustainable feedstocks for steam explosion-based torrefaction. The reaction conditions were optimized for each waste biomass by controlling the severity index (Ro); the higher heating value increased proportional to the Ro increase. Additionally, component analysis revealed that steam explosion torrefaction mainly degraded hemicellulose, and most of the torrefied waste biomass met the Bio-Solid Refuse Fuel quality standard. The results provide not only a viable waste-to-energy strategy but also insights to address global climate change.


Assuntos
Biocombustíveis , Vapor , Biomassa , Carbono , Madeira
4.
Bioresour Technol ; 371: 128628, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36646357

RESUMO

Levulinic acid is a significant platform chemical obtained from biomass and can potentially be used to produce value-added biofuels, biopolymers, and biopharmaceuticals. This study aims at statistically optimizing levulinic acid production from agrowastes. Based on the total carbohydrate content (71.93 %), corncob was selected as the target feedstock. A Box-Behnken design with four factors, such as feedstock concentration, reaction time, reaction temperature, and catalyst concentration, was used to optimize the hydrothermal conversion of corncob to levulinic acid at 180 °C for 30 min using 1 M H2SO4 as the acid catalyst and 120 g/L corncob. The maximum yield of 19.9 % was obtained. Additionally, 8.1 g/L formic acid was co-produced. The results of this study can contribute toward valorization of levulinic acid. Moreover, our results can be useful in developing strategies to utilize agrowastes as a renewable feedstock for recent biorefineries to cope with the climate crisis.


Assuntos
Ácidos Levulínicos , Zea mays , Temperatura , Ácidos , Biomassa
5.
World J Clin Cases ; 11(30): 7497-7501, 2023 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-37969461

RESUMO

BACKGROUND: Protein C deficiency is typically associated with venous thromboembolism; however, arterial thrombosis has been reported in several cases. We report the case of a patient with pulmonary thromboembolism and deep vein thrombosis following acute myocardial infarction with high thrombus burden. CASE SUMMARY: A 40-year-old man was diagnosed with pulmonary thromboembolism and deep vein thrombosis without any provoking factors. The patient was treated with anticoagulants for six months, which were then discontinued. Three months after the discontinuation of anticoagulant therapy, the patient was hospitalized with chest pain and diagnosed with acute myocardial infarction with high thrombus burden. Additional tests revealed protein C deficiency associated with thrombophilia. The patient was treated with anticoagulants combined with dual antiplatelet agents for 1 year after percutaneous coronary intervention, and no recurrent events were reported during a follow-up period of 5 years. CONCLUSION: Recurrent thromboembolic events including acute myocardial infarction with thrombus should be considered an alarming sign of thrombophilia.

6.
J Clin Med ; 12(13)2023 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-37445278

RESUMO

There are no data available comparing the real-world, long-term clinical outcomes of drug-eluting balloon (DEB) angioplasty and drug-eluting stent (DES) implantation in DES in-stent restenosis (ISR) lesions. We aimed to compare the real-world, long-term data available between DEBs and DESs in DES-ISR lesions. We analyzed consecutive DES-ISR lesions (225 lesions from 205 patients; male: 66.3%; mean age: 62.4 years) treated with either DEB or DES. The primary endpoint was target lesion revascularization (TLR), and the primary safety endpoint was the lesion-oriented composite outcome (LOCO). The LOCO is composed of cardiac death, myocardial infarction, and target lesion thrombosis during follow-up. During the 7-year follow-up period, TLR did not differ significantly between the DEB (n = 108) and the DES groups (n = 117) (HR: 1.07; 95% CI: 0.59-1.93, p = 0.83). The LOCO was significantly lower in the DEB group compared to the DES group (HR: 0.40; 95% CI: 0.16-0.98, p = 0.04), which was mainly driven by the lower levels of myocardial infarction (HR: 0.24; 95% CI: 0.06-0.94, p = 0.04) and the absence of target lesion thrombosis in the DEB group (vs. DES group 6%, p = 0.02). Additionally, cardiac death was found to be similar between the DEB and DES groups (HR: 0.56; 95% CI: 0.18-1.75, p = 0.32). DEB angioplasty showed favorable safety with a similar efficacy to that of DES implantation in DES-ISR lesions during the long-term follow-up period.

7.
Front Cardiovasc Med ; 10: 1249259, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37900574

RESUMO

Introduction: Patent foramen ovale (PFO) closure is performed in selected patients with cryptogenic stroke to prevent recurrence. The prognosis of patients with uncrossable PFO after failed guidewire or catheter passage during the procedure remains unknown. We compared the long-term prognosis between uncrossable PFO and successful PFO closure in patients with high-grade PFO shunts. Methods: We analyzed patients who underwent PFO closure for stroke or transient ischemic attack (TIA) prevention at Gachon University Gil Medical Center between April 2010 and March 2022. The primary outcome was a composite of recurrent stroke or TIA. Secondary outcomes included stroke, TIA, all-cause death, and a composite of stroke, TIA, and all-cause death. Results: Of 286 patients, 245 were included in the analysis after excluding those with transseptal puncture technique usage or concurrent atrial septal defect. Among them, 82 had uncrossable PFO, and 163 underwent successful PFO closure. Large shunts were more prevalent in the PFO closure group compared to the uncrossable PFO group (62.0% vs. 34.1%, P < 0.001), and resting shunts were also more common in the PFO closure group (17.8% vs. 2.4%, P < 0.001). Stroke or TIA occurred in 2 patients (2.4%) in the uncrossable PFO group and 8 patients (4.9%) in the PFO closure group (hazard ratio, 1.44; 95% confidence interval, 0.30-6.81; P = 0.647). Additionally, no disparities in the occurrence of stroke or TIA were found in subgroups divided by baseline characteristics, RoPE score, or shunt grade. Conclusion: Clinical outcomes for patients with uncrossable PFO seem similar to those with successful PFO closure.

8.
Bioresour Technol ; 359: 127501, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35753567

RESUMO

Given that traditional biorefineries have been based on microbial fermentation to produce useful fuels, materials, and chemicals as metabolites, saccharification is an important step to obtain fermentable sugars from biomass. It is well-known that glycosidic hydrolases (GHs) are responsible for the saccharification of recalcitrant polysaccharides through hydrolysis, but the discovery of lytic polysaccharide monooxygenase (LPMO), which is a kind of oxidative enzyme involved in cleaving polysaccharides and boosting GH performance, has profoundly changed the understanding of enzyme-based saccharification. This review briefly introduces the classification, structural information, and catalytic mechanism of LPMOs. In addition to recombinant expression strategies, synergistic effects with GH are comprehensively discussed. Challenges and perspectives for LPMO-based saccharification on a large scale are also briefly mentioned. Ultimately, this review can provide insights for constructing an economically viable lignocellulose-based biorefinery system and a closed-carbon loop to cope with climate change.


Assuntos
Lignina , Oxigenases de Função Mista , Biomassa , Lignina/metabolismo , Oxigenases de Função Mista/metabolismo , Polissacarídeos/metabolismo
9.
Bioresour Technol ; 348: 126832, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35149183

RESUMO

With concerns over global warming and climate change, many efforts have been devoted to mitigate atmospheric CO2 level. As a CO2 utilization strategy, formate dehydrogenase (FDH) from Clostridium species were explored to discover O2-tolerant and efficient FDHs that can catalyze CO2 to formate (i.e. CO2 reductase). With FDH from Clostridium ljungdahlii (ClFDH) that plays as a CO2 reductase previously reported as the reference, FDH from C.autoethanogenum (CaFDH), C. coskatii (CcFDH), and C. ragsdalei (CrFDH) were newly discovered via genome-mining. The FDHs were expressed in Escherichia coli and the recombinant FDHs successfully catalyzed CO2 reduction with a specific activity of 15 U g-1-CaFDH, 17 U g-1-CcFDH, and 8.7 U g-1-CrFDH. Interestingly, all FDHs newly discovered retain their catalytic activity under aerobic condition, although Clostridium species are strict anaerobe. The results discussed herein can contribute to biocatalytic CO2 utilization.


Assuntos
Dióxido de Carbono , Clostridium/enzimologia , Formiato Desidrogenases , Proteínas de Bactérias/genética , Dióxido de Carbono/metabolismo , Catálise , Clostridium/genética , Formiato Desidrogenases/genética , Formiatos/metabolismo
10.
World J Clin Cases ; 10(26): 9368-9377, 2022 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-36159436

RESUMO

BACKGROUND: Kawasaki disease (KD) is an acute self-limiting febrile vasculitis that occurs during childhood and can cause coronary artery aneurysm (CAA). CAAs are associated with a high rate of adverse cardiovascular events. CASE SUMMARY: A Korean 35-year-old man with a 30-year history of KD presented to the emergency room with chest pain. Emergent coronary angiography was performed as ST-segment elevation in the inferior leads was observed on the electrocardiogram. An aneurysm of the left circumflex (LCX) coronary artery was found with massive thrombi within. A drug-eluting 4.5 mm 23 mm-sized stent was inserted into the occluded area without complications. The maximal diameter of the LCX was 6.0 mm with a Z score of 4.7, suggestive of a small aneurysm considering his age, sex, and body surface area. We further present a case series of 19 patients with KD, including the current patient, presenting with acute coronary syndrome (ACS). Notably, none of the cases showed Z scores; only five patients (26%) had been regularly followed up by a physician, and only one patient (5.3%) was being treated with antithrombotic therapy before ACS occurred. CONCLUSION: For KD presenting with ACS, regular follow up and medical therapy may be crucial for improved outcomes.

11.
World J Clin Cases ; 10(27): 9897-9903, 2022 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-36186178

RESUMO

BACKGROUND: Aberrant right subclavian artery (ARSA) is the most common congenital anomaly of the aortic arch. When patients having such anomalies receive transradial intervention (TRI), aortic dissection (AD) may occur. Herein, we discuss a case of iatrogenic type B AD occurring during right TRI in an ARSA patient, that was later salvaged by percutaneous angioplasty. CASE SUMMARY: A 73-year-old man presented to our hospital with intermittent chest pain. Coronary computed tomography (CT) angiography revealed significant stenosis in the left anterior descending artery. Diagnostic coronary angiography was performed via the right radial artery without difficulty. However, we were unable to advance the guiding catheter past the ostium of the right subclavian artery to the aortic arch for percutaneous coronary intervention, while the guidewire tended to go down the descending aorta. The patient suddenly complained of chest and back pain. Emergent CT aortography revealed type B AD propagating to the left renal artery (RA) with preserved renal perfusion. However, after 2 d, the patient suddenly complained of right lower limb pain where the femoral pulse was suddenly undetectable. Follow-up CT indicated further progression of dissection to the right external iliac artery (EIA) and left RA with limited flow. We performed percutaneous angioplasty of the right EIA and left RA without complications. Follow-up CT aortography at 8 mo showed optimal results. CONCLUSION: A caution is required during right TRI in ARSA to avoid AD. Percutaneous angioplasty can be a treatment option.

12.
J Clin Med ; 11(11)2022 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-35683453

RESUMO

Blood type is reportedly correlated with the occurrence of cardiovascular diseases, presumably because of its effect on thrombogenicity. However, the relationship between blood type and thrombotic complications in atrial fibrillation (AF) remains unclear. This retrospective study analyzed the blood types of 1170 AF patients (mean age, 70 years; 58% men) who were followed up for up to 4 years. Patients with greater than mild mitral stenosis or prosthetic valves were excluded. The cohort included 305 (26%) type O, 413 (35%) type A, 333 (28%) type B, and 119 (10%) type AB patients. The primary endpoint of major adverse cerebrovascular events (MACE) occurred in 52 (4.4%) patients. When longitudinal outcomes were plotted, AB blood type patients had worse prognosis than non-AB blood type patients (p = 0.039), particularly type O blood patients (p = 0.049). Multivariate Cox regression analysis revealed that AB blood type was associated with higher MACE rates (adjusted hazard ratio, 2.01; 95% confidence interval, 1.01-4.00; p = 0.048) than non-AB blood types independent of anticoagulation therapy duration or CHA2DS2-VASc score. These indicate that AF patients with AB blood type are at an increased risk of MACE compared to those with non-AB blood type independent of the duration of anticoagulation or the CHA2DS2-VASc score.

13.
J Clin Med ; 11(3)2022 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-35159955

RESUMO

BACKGROUND: The decision-making factors and long-term clinical outcomes between PCI and CABG in left main (LM) disease are still not well defined in the real world. METHODS: We evaluated consecutive patients (n = 230) with LM disease either treated by PCI (n = 118) or CABG (n = 112). The primary endpoint was major adverse cardiovascular events (MACE), defined as a composite of cardiac death, spontaneous myocardial infarction (MI), stroke, and target vessel revascularization (TVR) for 7 years. RESULTS: In the multivariate-adjusted analysis, the presence of intermediate EuroSCORE II and high SYNTAX scores predisposed to CABG. Isolated LM disease was associated with receiving PCI. The PCI group had a similar rate of MACE (HRadj 0.97, 95% CI [0.48-1.94], p = 0.92) and a lower tendency of hard MACE (HRadj 0.49, 95% CI [0.22-1.07], p = 0.07) compared to the CABG group, mainly due to the balance between a higher rate of TVR (HRadj 9.71, p = 0.02) and a lower rate of stroke (HRadj 0.22, p = 0.09) with the PCI group than in the CABG group. CONCLUSIONS: The decision making of treatment strategy was made based on clinical and angiographic factors. The selected patients who received PCI showed similar MACE and trend of a lower rate of composite hard endpoints despite multivariate adjustment.

14.
Bioresour Technol ; 346: 126358, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34800638

RESUMO

Microalgae have been studied and tested for over 70 years. However, biodiesel, the prime target of the algal industry, has suffered from low competitiveness and current steps toward banning the internal combustion engine all over the world. Meanwhile, interest in reducing CO2 emissions has grown as the world has witnessed disasters caused by global warming. In this situation, in order to maximize the benefits of the microalgal industry and surmount current limitations, new breakthroughs are being sought. First, drop-in fuel, mandatory for the aviation and maritime industries, has been discussed as a new product. Second, methods to secure stable and feasible outdoor cultivation focusing on CO2 sequestration were investigated. Lastly, the need for an integrated refinery process to simultaneously produce multiple products has been discussed. While the merits of microalgae industry remain valid, further investigations into these new frontiers would put algal industry at the core of future bio-based economy.


Assuntos
Microalgas , Biocombustíveis , Biomassa , Plantas
15.
Bioresour Technol ; 346: 126605, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34953994

RESUMO

Gas fermentation utilizes syngas converted from biomass or waste as feedstock. A bubble column reactor for pressurizing was designed to increase the mass transfer rate between gas and liquid, and reduce energy consumption by medium agitation. Thermococcus onnurineus, a hydrogenic CO-oxidizer, was cultured initially under ambient pressure with the initial inlet gas composition; 60% CO and 40% N2. The maximum H2 productivity was 363 mmol/l/h, without pH adjustment. When additional pressure was applied, the pH rapidly declined; this may be attributed to the increased CO2 solubility under pressure. By controlling pH, H2 productivity increased up to 450 mmol/l/h; which is comparable to the previously reported H2 productivity in a continuous stirred tank reactor. The results may suggest energy saving potentials of bubble column reactors in gas fermentation. This finding may be applied to other gas fermentation processes, as syngas itself contains CO2 and many microbial processes also release CO2.


Assuntos
Reatores Biológicos , Monóxido de Carbono , Fermentação , Hidrogênio , Concentração de Íons de Hidrogênio
16.
Bioresour Technol ; 337: 125479, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34320759

RESUMO

Given that (i) levulinic acid (LA) is one of the most significant platform chemicals derived from biomass and (ii) 4-hydroxyvaleric acid (4-HV) is a potential LA derivative, the aim of this study is to achieve chemoenzymatic valorization of LA, which was obtained from agricultural wastes, to 4-HV. The thermochemical process utilized agricultural wastes (i.e., rice straw and corncob) as feedstocks and successfully produced LA, ranging from 25.1 to 65.4 mM. Additionally, formate was co-produced and used as a hydrogen source for the enzymatic hydrogenation of LA. Finally, engineered 3-hydroxybutyrate dehydrogenase from Alcaligenes faecalis (eHBDH) was applicable for catalyzing the conversion of agricultural wastes-driven LA, resulting in a maximum concentration of 11.32 mM 4-HV with a conversion rate of 48.2%. To the best of our knowledge, this is the first report describing the production of 4-HV from actual biomass, and the results might provide insights into the valorization of agricultural wastes.


Assuntos
Ácidos Levulínicos , Valeratos , Biomassa
17.
Bioresour Technol ; 320(Pt A): 124350, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33186841

RESUMO

The electrochemical conversion of CO2 can include renewable surplus electricity storage and CO2 utilisation. This review focuses on the microbial CO2 electrobiorefinery based on microbial electrosynthesis (MES) which merges electrochemical and microbial conversion to produce biofuels and higher-value chemicals. In this review, recent developments are discussed about bioelectrochemical conversion of CO2 into biofuels and chemicals in MES via microbial CO2-fixation and electricity utilisation reactions. In addition, this review examines technical approaches to overcome the current limitations of MES including the following: engineering of the biocathode, application of electron mediators, and reactor optimisation, among others. An in-depth discussion of strategies for the CO2 electrobiorefinery is presented, including the integration of the biocathode with inorganic catalysts, screening of novel electroactive microorganisms, and metabolic engineering to improve target productivity from CO2.


Assuntos
Dióxido de Carbono , Eletricidade , Biocombustíveis , Catálise , Eletrodos , Engenharia Metabólica
18.
Bioresour Technol ; 305: 123155, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32178996

RESUMO

Due to climate change, recent research interests have increased towards CO2 utilization as a strategy to mitigate the atmospheric CO2 level. Herein, we aimed to explore formate dehydrogenases (FDHs) from chemoautotroph to discover an efficient and O2-tolerant biocatalyst for catalyzing the CO2 reduction to a versatile formate. Through genome-mining and phylogenetic analysis, the FDH from Rhodobacter aestuarii (RaFDH) was newly discovered as a promising O2-tolernat CO2 reductase and was successfully expressed in Escherichia coli. In this study, the optimum conditions and turnover rates of RaFDH were examined for CO2 reduction and formate oxidation. In particular, the RaFDH-driven CO2 reduction far surpassed the formate oxidation with a turnover rate of 48.3 and 15.6 min-1, respectively. The outstanding superiority of RaFDH towards CO2 reduction can be applicable for constructing a feasible electroenzymatic system that produce a versatile formate from CO2 as a cheap, abundant, and renewable resource.


Assuntos
Dióxido de Carbono , Formiato Desidrogenases , Formiatos , Oxirredução , Filogenia , Rhodobacter
19.
Bioresour Technol ; 99(5): 1196-203, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17416517

RESUMO

To improve the oxidation stability and the low temperature flow properties of a biodiesel mixture, the dependence of the oxidation stability and the cold filter plugging point (CFPP) on the fatty acid compositions was examined. Three different kinds of biodiesels, palm, rapeseed, and soybean biodiesels, were blended with the different weight ratios. The oxidation stability and the CFPP of the blended biodiesels had a close relationship with the compositions of the major fatty acid components. The oxidation stability of the blended biodiesels decreased as the total contents of the linoleic and linolenic acids increased. The correlation was obtained as Y=117.9295/X+2.5905 (0

Assuntos
Biotecnologia , Temperatura Baixa , Gasolina , Ácidos Graxos Monoinsaturados , Oxirredução , Óleo de Palmeira , Óleos de Plantas/química , Óleo de Brassica napus , Óleo de Soja/química
20.
Polymers (Basel) ; 10(6)2018 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-30966710

RESUMO

The surface area and pore size distribution of Eucalyptus samples that were pretreated by different methods were determined by the Brunauer⁻Emmett⁻Teller (BET) technique. Three methods were applied to prepare cellulosic biomass samples for the BET measurements, air, freeze, and critical point drying (CPD). The air and freeze drying caused a severe collapse of the biomass pore structures, but the CPD effectively preserved the biomass morphology. The surface area of the CPD prepared Eucalyptus samples were determined to be 58⁻161 m²/g, whereas the air and freeze dried samples were 0.5⁻1.3 and 1.0⁻2.4 m²/g, respectively. The average pore diameter of the CPD prepared Eucalyptus samples were 61⁻70 Å. The CPD preserved the Eucalyptus sample morphology by replacing water with a non-polar solvent, CO2 fluid, which prevented hydrogen bond reformation in the cellulose.

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