Search

To facilitate value-added chemical production from renewable glycerol, gas-phase glycerol dehydration to acrolein was conducted using supported silicotungstic acid as solid acid catalysts, focusing on the effects of mesoporous catalyst supports on the catalytic performance. One alumina (Al) support with average mesopore size of 30 nm and two silica supports (Si1254 and Si1252) with mesopore size of 6 nm and 11 nm, respectively, were comparatively evaluated in this study. It was found that the Si1254 silica support with the smallest pore size (6 nm) deactivated the fastest, decreasing both the glycerol conversion and acrolein selectivity along the time-on-stream. The other silica support Si1252 with 11 nm pore size provided an acrolein yield comparable to the Al support over the tested 7.5 h time-on-stream (73.9 mol% for Si1252 vs. 74.1 mol% for Al). However, the mechanisms for achieving the comparable yield are different. Si1252 showed higher acrolein selectivity than Al, but it also deactivated faster than Al due to its quicker coking. On the other hand, Al showed more stable performance in terms of glycerol conversion rate and less coking, but it had lower acrolein selectivity and a higher selectivity to byproducts, especially the undesired byproducts of acetaldehyde and propionaldehyde, which posed difficulties in downstream separation.

This study uses real-time FTIR spectroscopy to probe biochemical changes occurring in spores of Bacillus amyloliquefaciens during nutrient germination at T = 23 − 50°C and after sub-lethal injury by treatment with a nonthermal plasma (NTP). The FTIR identifies several spore structural components (e.g., stretching bands of the COO− group of dipicolinic acid at 1378 and 1616 cm−1; C−N vibrations in the DPA ring at 1570 cm−1, etc.) that are correlated to steps occurring during germination. The increase in peak intensity at 1570 cm−1 is interrelated to spore germination as measured with optical density at 600 nm (OD600) of refractile spores at T = 23 − 50°C and after NTP treatment. For the OD600 germination kinetics data, the Weibull model accurately fit the observed dynamics with values for the rate parameters α = 18.1 − 52.9 s−1 and shape parameter β = 0.9 − 1.2, and the Weibull model's performance was assessed by satisfactory values of the accuracy factor (1.00 < Af ≤ 1.15) and the bias factor (Bf in the ranges of 0.90 − 1.05), with the NTP-treated spores being the lone exception (Af = 1.22, Bf = 1.06).

To overcome the recalcitrance of para-aramid textiles against dyeing, this study demonstrated that increasing the functionalities of soybean oil applied to the surface of para-aramids followed by a nonthermal plasma (NTP) treatment improved the dyeing color strength compared with the use of soybean oil alone, and that dyeing occurred through covalent bonding. Particularly, compared with the pretreatment using soybean oil that obtained the highest color strength of 3.89 (as K/S value determined from spectral analysis of the sample reflectance in the visible range), the present pretreatments with either acrylated epoxidized soybean oil (AESO) or a mixture of acrylic acid and soybean oil (AA/Soy) achieved K/S values higher than nine (>9.00). The NTP treatment, after the AESO or AA/Soy pretreatment, was essential in inducing the formation of a polymerized network on the surface of para-aramids that bonded the dye molecules and generating covalent bonds that anchored the polymerized network to the para-aramids, which is difficult to achieve given the high crystallinity and chemical inertness of para-aramids. As an important economic consideration, the sequential experimentation method demonstrated that a simple mixture of AA/Soy could replace the expensive AESO reagent and render a comparable performance in dyeing para-aramids. Among the auxiliary additives tested with the AESO and AA/Soy pretreatments followed by NPT treatment in this study, Polysorbate 80 as a surfactant negatively affected the dyeing, benzyl alcohol as a swelling agent had minimal effect, and NaCl as an electrolyte showed a positive effect. The dyeing method developed in this study did not compromise the strength of para-aramids.

The increasing use of functional aramids in a wide array of applications and the inert nature of aramids against conventional dye and print methods requires developing new dyeing methods. This study aims to use environmentally friendly method with a cationic dye as an alternative for dyeing para-aramid fabrics. Experiments used a multi-factorial design with functions of pretreatment, dye solvent (water and/or glycerol) and auxiliary chemical additives (swelling agent and surfactant) and a sequential experimentation methodology. The most effective dyeing procedures involved the following steps: (i) pretreatments of the fabrics with soybean oil and nonthermal plasma (NTP), (ii) using water at T = 100 °C as the dye solvent, and (iii) omitting other chemical additives. With a commercial cationic dye, these conditions achieved a color strength in K/S value of 2.28, compared to ~1 for untreated samples. FTIR analysis revealed that a functional network formed on the fibers and yarns of the fabrics by chemical reactions of excited plasma species with double bonds in the soybean oil molecules was responsible for significantly improving the color strength. These results extend the potential uses of a renewable material (soybean oil) and an environmentally friendly technology (NTP) to improve the dyeing of para-aramid textiles and reduce the use of harsh dye chemicals.

Objective: To determine the safety and efficacy of flow reversal following proximal flow arrest as an embolic protection strategy for carotid angioplasty and stenting (CAS) with short-term follow-up. Method: We performed a retrospective review of our CAS database for patients who underwent stent-supported carotid revascularization in the setting of acute/subacute stroke or TIA. We reviewed clinical and radiographic data during a 36-month period. Primary outcome was clinical evidence of ipsilateral stroke in the first 30 days. Secondary outcomes include clinical outcomes and sonographic and/or angiographic follow-up over 6 months, 6-month functional scale, and all-cause mortality. Results: Fifty-five patients underwent CAS using flow reversal: 26 females and 29 males with a mean age of 69.7 years. Median time to treatment from index event was 3 days. 11% underwent stenting as part of hyperacute stroke therapy. Average luminal stenosis was 86%. The 9-Fr Mo.Ma device was used in combination with Penumbra aspiration in all cases. There were no ipsilateral strokes. Incidence of any ischemic event was 3.64%, but only 1 (1.82%) patient had a postoperative stroke. Clinical follow-up was available for 94.5%, while lesion follow-up was available for 73% of patients. Three patients had evidence of restenosis, but none were symptomatic. Luminal restenosis was ≤30% in all three. Median pre- and post-NIHSS were 1 and 1, respectively. Conclusion: Flow reversal using the Mo.Ma device is a safe and effective strategy in preventing distal embolization during carotid artery revascularization.

Fractionation of crude bio-oil into an organic phase and an aqueous phase by simply adding water and research strategies targeted at producing hydrogen, fuels, or other value-added chemicals from the fractions have been proposed. However, the stability of the bio-oil fractions has not been comprehensively investigated. The objective of this study was to comparatively investigate the stability of crude bio-oil and its two fractions by evaluating their physicochemical properties during long-term storage at room temperature and accelerated aging at 40 °C and 60 °C. Comparing with crude bio-oil, the resulted aqueous phase is more stable; for the organic phase, the stability is also improved in terms of the changes in viscosity and average molecular weight, but not in terms of the increasing water content and total acid number. In overview for all the crude bio-oil and its two fractions, the water content, viscosity, total acid number, and average molecular weight increased with the increase of aging time and temperature; except for acetic acid and propionic acid, which slightly increased in content at all aging conditions, all the other 13 measured chemical contents decreased with the increasing aging time and temperature, indicating that the aging process involved all the six chemical groups of anhydrosugars, carboxylic acids, alcohols, furans, ketones, and phenolics, accelerated at higher temperature.

Despite the potential carbon-neutrality of switchgrass bio-oil, its high acidity and diverse chemical composition limit its utilization. The objectives of this research are to investigate pH neutralization of bio-oil by adding various alkali solutions in a batch system and then perform neutralization using process intensification devices, including a static mixer and a centrifugal contactor. The results indicate that sodium hydroxide and potassium hydroxide are more appropriate bases for pH neutralization of bio-oil than calcium hydroxide due to the limited solubility of calcium hydroxide in aqueous bio-oil. Mass and total acid number (TAN) balances were performed for both batch and continuous-flow systems. Upon pH neutralization of bio-oil, the TAN values of the system increased after accounting the addition of alkali solution. A bio-oil heating experiment showed that the heat generated during pH neutralization did not cause a significant increase in the acidity of bio-oil. The formation of phenolic comp...

To develop and validate an itemized costing algorithm for in-patient neonatal intensive care unit (NICU) costs for infants born prematurely that can be used for quality improvement and health economic analyses.We sourced patient resource use data from the Canadian Neonatal Network database, with records from infants admitted to 30 tertiary NICUs in Canada. We sourced unit cost inputs from Ontario hospitals, schedules of benefits, and administrative sources. Costing estimates were generated by matching patient resource use data to the appropriate unit costs. All cost estimates were in 2017 Canadian dollars and assigned from the perspective of a provincial public payer. Results were validated using previous estimates of inpatient NICU costs and hospital case-cost estimates.We assigned costs to 27 742 infants born prematurely admitted from 2015 to 2017. Mean (SD) gestational age and birth weight of the cohort were 31.8 (3.5) weeks and 1843 (739) g, respectively. The median (IQR) cost of hospitalization before NICU discharge was estimated as $20 184 ($9739-51 314) for all infants; $11 810 ($6410-19 800) for infants born at gestational age of 33-36 weeks; $30 572 ($16 597-$51 857) at gestational age of 29-32 weeks; and $100 440 ($56 858-$159 3867) at gestational age of29 weeks. Cost estimates correlated with length of stay (r = 0.97) and gestational age (r = -0.65). The estimates were consistent with provincial resource estimates and previous estimates from Canada.NICU costs for infants with preterm birth increase as gestation decreases and length of stay increases. Our cost estimates are easily accessible, transparent, and congruent with previous cost estimates.

To examine rates and determinants of mother's own milk (MOM) feeding at hospital discharge in a cohort of infants born very preterm within the Canadian Neonatal Network (CNN).This was a population-based cohort study of infants born at33 weeks of gestation and admitted to neonatal intensive care units (NICUs) participating in the CNN between January 1, 2015, and December 31, 2018. We examined the rates and determinants of MOM use at discharge home among the participating NICUs. We used multivariable logistic regression analysis to identify independent determinants of MOM feeding.Among the 6404 infants born very preterm and discharged home during the study period, 4457 (70%) received MOM or MOM supplemented with formula. Rates of MOM feeding at discharge varied from 49% to 87% across NICUs. Determinants associated with MOM feeding at discharge were gestational age 29-32 weeks compared with26 weeks (aOR 1.56, 95% CI 1.25-1.93), primipara mothers (aOR 2.12, 95% CI 1.86-2.42), maternal diabetes (aOR 0.79, 95% CI 0.66-0.93), and maternal smoking (aOR 0.27, 95% CI 0.19-0.38). Receipt of MOM by day 3 of age was the major predictor of breast milk feeding at discharge (aOR 3.61, 95% CI 3.17-4.12).Approximately two-thirds of infants born very preterm received MOM at hospital discharge, and rates varied across NICUs. Supporting mothers to provide breast milk in the first 3 days after birth may be associated with improved MOM feeding rates at discharge.

Background One of the controversies in the management of twin gestations relates to mode of delivery, especially when the second twin is in a nonvertex presentation (Vertex/nonVertex pairs) and birth is imminent at extremely low gestation. Objective We hypothesized that, for Vertex/nonVertex twins born before 28 weeks’ gestation, cesarean delivery would be associated with a lower risk of adverse neonatal outcomes than trial of vaginal delivery. Our aim was to test this hypothesis by comparing the neonatal outcomes of Vertex/nonVertex twins born before 28 weeks’ gestation by mode of delivery using a large national cohort. Study Design This work is a retrospective cohort study of all twin infants born at 240/7 to 276/7 weeks’ gestation and admitted to level III neonatal intensive care units participating in the Canadian Neonatal Network (2010–2017). Exposure is defined a trial of vaginal delivery for Vertex/nonVertex twins. Nonexposed (control) groups are defined as cases where both twins were delivered by cesarean delivery, either in vertex or nonvertex presentation (control group 1) or owing to the nonvertex presentation of the first twin (control group 2). Outcome measures are defined as a composite of neonatal death, severe neurologic injury, or birth trauma. Results A total of 1082 twin infants (541 twin pairs) met the inclusion criteria: 220 Vertex/nonVertex pairs, of which 112 had a trial of vaginal delivery (study group) and 108 had cesarean delivery for both twins (control group 1); 170 pairs with the first twin in nonvertex presentation, all of which were born by cesarean delivery (control group 2); and 151 pairs with both twins in vertex presentation (vertex or nonvertex). In the study group, the rate of urgent cesarean delivery for the second twin was 30%. The rate of the primary outcome in the study group was 42%, which was not significantly different compared with control group 1 (37%; adjusted relative risk, 0.93; 95% confidence interval, 0.71–1.22) or control group 2 (34%; adjusted relative risk, 1.20; 95% confidence interval, 0.92–1.58). The findings remained similar when outcomes were analyzed separately for the first and second twins. Conclusion For preterm Vertex/nonVertex twins born at

The chemical complexity of bio-oil aqueous phase limits its efficient utilization. To improve the efficiency of the bio-oil biorefinery, this study focused on the separation of chemical groups from the bio-oil water-extract via sequential organic solvent extractions. Due to their high recoverability and low solubility in water, four solvents (hexane, petroleum ether, chloroform, and ethyl acetate) with different polarities were evaluated, and the optimum process conditions for chemical extraction were determined. Chloroform had high extraction efficiency for furans, phenolics, and ketones. In addition to these classes of chemical, ethyl acetate had a high extraction efficiency for organic acids. The sequential extraction using chloroform followed by ethyl acetate resulted in 62.2 wt.% of original furans, ketones, alcohols, and phenolics being extracted into chloroform, while 62 wt.% acetic acid was extracted into ethyl acetate, leaving behind a high concentration of levoglucosan (∼53.0 wt.%) in the final aqueous phase. Chemicals separated via the sequential extraction could be used as feedstocks in a biorefinery using processes such as catalytic upgrading of furans and phenolics to hydrocarbons, fermentation of levoglucosan to produce alcohols and diols, and hydrogen production from organic acids via microbial electrolysis.

Supercritical carbon dioxide (SC‐CO2) has been used for the first time as a reaction medium for the dehydration of glycerol to acrolein catalyzed by a solid acid. Unprecedented catalyst stability over 528 hours of time‐on‐stream was achieved and the rate of coke deposition on the zeolite catalyst was the lowest among extensive previous studies, showing potential for industrial application. Coking pathways in SC‐CO2 were also elucidated for future development. The results have potential implications for other dehydration reactions catalyzed by solid acids.

To efficiently utilize water-soluble compounds in bio-oil and evaluate the potential effects of these compounds on processes such as microbial electrolysis, this study investigated the physicochemical properties of bio-oil and the associated aqueous phase generated from switchgrass using a semi-pilot scale auger pyrolyzer. Combining separation and detection strategies with organic solvent extraction, an array of analytical instruments and methods were used to identify and quantify the chemical constituents. Separation of an aqueous phase from the crude bio-oil was achieved by adding water (water: crude bio-oil at 4:1 in weight), which resulted in a partition of 61 wt.% of the organic compounds into a bio-oil aqueous phase (BOAP). GC/MS analysis for BOAP identified over 40 compounds of which 16 were quantified. Acetic acid, propionic acid, and levoglucosan are the major components in BOAP. In addition, a significant portion of chemicals that have the potential to be upgraded to hydrocarbon fuels was extracted to BOAP (77 wt.% of the alcohols, 61 wt.% of the furans, and 52 wt.% of the phenolic compounds in crude bio-oil). Valorization of the BOAP may require conversion methods capable of accommodating a very broad substrate specificity. A better separation strategy is needed to selectively remove the acidic and polar components from crude bio-oil to improve economic feasibility of biorefinery operations.

The feasibility of fabricating better solid acid catalysts using nonthermal plasma (NTP) technology for biobased acrolein production is demonstrated. NTP discharge exposure was integrated in catalyst fabrication in air or argon atmosphere. The fabricated catalysts were characterized by Brunauer–Emmett–Teller surface area analysis, temperature-programmed desorption of ammonia, X-ray powder diffraction and Fourier-transform infrared spectroscopy of pyridine adsorption, in comparison to regularly prepared catalysts as a control. Further, kinetic results collected via glycerol dehydration experiments were compared, and improvement in acrolein selectivity was displayed when the catalyst was fabricated in the argon NTP, but not in the air NTP. Possible mechanisms for the improvement were also discussed.

Producing value-added chemicals from glycerol is imperative for the sustainable future of biodiesel. Despite worldwide efforts, the commercial production of acrylic acid from glycerol faces challenges, both technologically and economically. Based on our new technology using CO2 as a reaction medium in a two-step process to catalytically convert glycerol to acrylic acid, we established computer simulation models to analyze the energy efficiency and estimate production costs at different scenarios. The analysis was conducted in conjunction with published data of a typical, intermediate-sized biodiesel facility, aiming at the feasibility of producing acrylic acid on-site in the context of a circular economy. Variable analysis in response to the market value of glycerol, the source and cost of carbon dioxide recycling, and the changes in process scale and conditions are also presented. Results indicates that a cost-effective supply of CO2 to the acrylic acid plant is key to the further research and development.

International audience; Booming biodiesel production worldwide demands valorization of its byproduct of glycerol. Acrolein, an important intermediate chemical, can be produced by gas-phase glycerol dehydration catalyzed by solid acids. Because catalysts that lead to high acrolein selectivity usually deactivate rapidly due to the formation of coke that blocks the active sites on their surface, one major challenge of this method is how to extend the service life of the catalyst. Silica-supported silicotungstic acid (HSiW-Si) is a good example of such a catalyst that shows good activity in glycerol dehydration to acrolein initially, but deactivates quickly. In this study, HSiW-Si was selected to probe the potential of using non-thermal plasma with oxygen-containing gas as the discharge gas (NTP-O2) to solve the catalyst deactivation problem. NTP-O2 was found to be effective in coke removal and catalyst regeneration at low temperatures without damaging the Keggin structure of the HSiW-Si catalyst.

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organic solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a bi...

With the aim to directly use the mixture of glycerol and methanol from the biodiesel production for value-added chemical production, catalytic conversion of refined glycerol to lactic acid (LA) and propylene glycol (PG) using mixed solid catalysts of CaO and CuO in methanol medium was first investigated. At the optimum condition, the yields of LA and PG achieved were 46 mol% and 35 mol%, respectively. For recycling the catalysts, a combined process of glycerol conversion to alkyl lactate was further investigated. Using this integrated process, 45 mol% methyl lactate yield and 28 mol% PG yield were achieved in methanol medium, and 45 mol% ethyl lactate and 18 mol% PG yield were achieved in ethanol medium. The test for crude glycerol conversion showed that the impurities had slightly negative effects on glycerol conversion and product yield in methanol medium but no obvious effect in ethanol medium. Similar glycerol conversion and product yield were obtained when the mixture of glycerol, methanol, and CaO from biodiesel production were directly used as starting material. This result suggests that the mixture from biodiesel production can be directly used to produce valued-added chemicals such as methyl lactate and PG.

Development of value-added chemicals from glycerol, the co-product with biodiesel, is imperative in sustaining the biodiesel industry. Combined usage of a solid base and a copper-based catalyst provided a catalytic pathway to convert glycerol to racemic lactic acid. A new pathway was found that during the glycerol-to-lactic acid conversion, hydrogen was formed, which could be used in situ to generate propylene glycol catalyzed by the copper-based catalyst. This new pathway was attested by results of systematically experimental study investigating the synergistic functions of a base catalyst (CaO, MgO, or SrO) and a copper-based dehydrogenation catalyst (Cu, CuO, Cu2O, or Cu2Cr2O5). Different combinations of catalysts and reaction conditions provided a tunable range for the yield of lactic acid and propylene glycol. Emphasis was put on the combined use of CuO and CaO due to their inexpensive availability and ease of recyclability; at optimal reaction conditions, the yield of lactic acid reached 52 mol% together with 31 mol% yield of propylene glycol.

BACKGROUND Estimation of right ventricular peak systolic pressure (RVSP) or pulmonary pressure using echocardiography is crucial in neonates with acute or chronic pulmonary hypertension. Conventionally in echocardiography, the maximal velocity of the Tricuspid Regurgitant jet (TR Vmax) is used to estimate the RVSP. However, TR jet can often be absent or unmeasurable in neonates, resulting in a need to search for alternative echocardiographic measures of pulmonary pressure in neonates. Pulmonary Artery Doppler Waveform Parameter known as Pulmonary Artery Acceleration Time (PAAT) has been investigated in adults and older children and found to be reliable in estimating pulmonary pressure. To date, no such validation study exists for neonates.Hence we designed this study to explore the role of Pulmonary Artery Acceleration Time in estimating pulmonary pressures in neonates. OBJECTIVES To identify the pulmonary artery doppler waveform parameter that most closely reflects pulmonary pressure and analyse the impact of baseline variables and measurement techniques on this relationship. DESIGN/METHODS This was a retrospective cohort analysis conducted at two tertiary neonatal intensive care units. All neonates who underwent Targeted Neonatal Echocardiographic(TnECHO) assessments over May 2014-May 2017 were assessed for eligibility. Neonates whose echocardiography revealed a complete, measurableTR jet were included. Baseline characteristics such as gestational age, chronological age at echo, weight, blood pressure, ventilation and diagnosis were collected. Echocardiographic parameters such as TR Vmax, Pulmonary artery doppler waveform parameters such as Right Ventricular Ejection Time (RVET) and Pulmonary Artery Acceleration Time (PAAT) were measured by a single expert operator. Pulmonary Vascular Resistance Index (PVRI) was calculated as a ratio between RVET and PAAT. Correlation between pulmonary artery waveforms and RVSP estimated from the TR jet was examined using Pearson or Spearman analysis as appropriate. Univariate and multivariate regression analysis was used to further explore the influence of relevant factors on this relationship. Ethical approval was obtained from the institutional ethic board. RESULTS 678 neonates with 1767 echocardiographic studies were screened for eligibility of which 201 scans were included. Mean gestational age of this cohort was 30.5+/-5.7 weeks with mean birthweight of 1635 +/-1115 grams. Pulmonary Vascular Resistance Index (ratio of RVET to PAAT) also known as indexed PAAT, measured by Pulsed Wave Doppler at the level of the main pulmonary artery was found to have the strongest correlation with RVSP estimated from TRVmax. [r=0.45,P CONCLUSION This important validation study shows that PAAT indexed to right ventricular ejection time(PVRI) has statistically significant correlation with pulmonary pressures as measured by TR jet in neonates. However the strength of correlation in neonates is moderate at best. The measurement is feasible with good interobserver agreement and potentially can play an important role in serial monitoring of pulmonary pressures in neonates without any demonstrable TR jet on echocardiography.

This study investigated alkyl lactate production from glycerol by tandem processes which included glycerol conversion to calcium lactate using solid catalysts and subsequent transesterification of calcium lactate to alkyl lactate using methanol/ethanol and carbon dioxide. The effect of reaction conditions on alkyl lactate production was systematically investigated. A central composite design (CCD) and response surface methodology were used to design the experiments and evaluate the optimum process conditions. At the optimum conditions, the methyl lactate yield reached 57 mol% with a glycerol conversion of 94 mol% using refined glycerol. A yield of approximately 42 mol% for ethyl lactate was obtained using refined glycerol at the optimum conditions. Similar glycerol conversion and alkyl lactate yields were obtained using crude glycerol, indicating that the impurities in the crude glycerol had no significant effects on alkyl lactate production. The examination of regenerated catalysts that had been reused twice showed no negative effects on glycerol conversion and methyl lactate production. Compared to the traditional lactic acid and alkyl lactate production, this two-step process for alkyl lactate production from glycerol is both economical and environmentally benign since no gypsum was produced and the solid catalysts can be regenerated and reused.

The recent endeavor toward a bio-based economy in the U.S. leads to more attention to converting organic matters into bio-fuels. Efforts have been made to look for practical applications for bio-char, a carbonaceous by-product from converting plant matters to bio-fuels through pyrolysis. Bio-char is considered to be able to use as an asphalt binder modifier due to its carbon nature and morphology. In this study, bio-char derived from switchgrass through different types of pyrolysis were tested as bio-modifier for asphalt binder. A commercially activated carbon was utilized for comparison. All the carbonaceous additives were incorporated into one commonly used asphalt binder at different concentrations in order to obtain the optimal content. The samples were tested in the laboratory for their rheological characteristics, rutting and fatigue performance and ductility properties. Highest treatment temperature (HTT), pyrolysis method, particle size of bio-modifier and modifier content were investigated to achieve the optimal modification effect. It was found that bio-char was capable of reducing the temperature susceptibility and significantly increasing the rutting resistance of the asphalt binder. The addition of the bio-char showed little effect on the fatigue and cracking resistance, with the best fatigue and cracking resistance found on the bio-char with finer particles (−75 μm) produced at lower HTT (400 °C) and lower heating rate (15 °C/min). Based on the testing results, bio-char appears to be a more effective binder modifier than commercially activated carbon within addition of 10 wt.%.

This study investigated a fed-batch process for glycerol conversion to lactic acid with sodium hydroxide (NaOH) as homogeneous catalyst, with the aim to reduce the corrosiveness of catalyst to reactor. At the optimal conditions of the fed-batch process (1.1 M initial glycerol concentration, reaction time of 220 min, reaction temperature of 300 °C, NaOH concentration around 0.2 M), lactic acid yield reached 82 mol%, with 93 mol% of glycerol conversion. A first order kinetic model in the fed-batch conversion of glycerol was developed and validated under different process conditions. The corrosiveness to stainless steel reactor in glycerol conversion in the fed-batch process, measured as Fe3+ at the end of reaction, decreased from 9.5 to 1.5 ppm Fe3+ when compared to a batch process using a homogeneous 1.25 M NaOH as catalyst. Application of the fed-batch reactor in the crude glycerol conversion reached the maximum lactic acid yield of 72.9 mol% with 92.4 mol% glycerol conversion, but high soap content in crude glycerol has negative effects on both lactic acid yield and glycerol conversion.

In the valorization of glycerol as byproduct of biodiesel production, although recent progress in glycerol conversion to lactic acid using homogeneous chemocatalysis showed promising high yield, the used high alkalinity entails high corrosiveness to reactors and problematic downstream separations. In this study, five solid base catalysts were screened for converting glycerol to lactic acid with the aim to ease corrosiveness, focusing on inexpensive CaO as a promising solid base. Process conditions were systematically investigated for optimization. The highest yield of lactic acid achieved was 40.8 mol% with a glycerol conversion of 97.8 mol% at the optimum conditions using refined glycerol. Similar conversion rate and lactic acid yield were also obtained in the conversion of crude glycerol using CaO if the water content in crude glycerol is lower than 10%. CaO exhibited lower activation energy in converting glycerol to lactic acid compared to homogeneous NaOH catalyst. Corrosiveness to reactor using CaO was proven much lower than that using homogeneous NaOH catalyst. CaO as catalyst for both biodiesel production and subsequent crude glycerol conversion to lactic acid was investigated, revealing its potential industrial applications for the production of both biodiesel and lactic acid.

The United States is promoting the establishment of a bio-based economy, generating energy and fuels from renewable organic matters rather than fossil fuels. Byproducts such as fractions of biochar not suitable for biofuel production are drawing extensive attention. (“Biochar” is defined by Oxford's online dictionary as “charcoal produced from plant matter and stored in the soil as a means of removing carbon dioxide from the atmosphere.”) Recently, biochar produced with different production parameters was tried as an asphalt modifier owing to its carbon origin and proved to be positive in binder modification. This study evaluated the performance of hot-mix asphalt modified by one type of pyrolytic biochar with controlled production parameters. Typical carbon black powder pellets and microsized carbon fiber were selected as the reference additives. Multiple laboratory binder and performance tests were conducted to evaluate the rheological properties of the modified binder, rutting resistance, moisture susceptibility, and cracking resistance of asphalt mixtures. On the basis of test results, the biochar evaluated in this study proved to be an effective modifier in reducing the temperature susceptibility of the binder and thus increased the rutting, moisture, and cracking resistance of hot-mix asphalt. In addition, biochar proved to be a better asphalt modifier than did carbon black and carbon fiber.

Foamed warm-mix asphalt (WMA) has been widely accepted and used in the United States and many other countries around the world. However, several key concerns about WMA technology still need to be answered, including the major issue of moisture-induced damage. Because of the reduced production temperatures and the foaming process with water, moisture may be entrapped in pavements after compaction. The trapped moisture decreases the adhesion between asphalt binder and aggregates and the cohesion among asphalt binder, resulting in stripping and other forms of pavement distress. The neutron scattering technique provides a unique tool for the determination of the microscopic structure of asphalt and for the detection of the presence of moisture and its spatial distributions in asphalt. In particular, small-angle neutron scattering (SANS) in the wave vector transfer range from 0.003−0.5 A−1 is suitable to probe the spatial density fluctuations in the real space from 200−1 nm, which has a resolution se...

To better understand the effects of water properties on the reaction characteristics of acrolein production from glycerol, dehydration of refined glycerol and crude glycerol was comparatively conducted in both sub- and super-critical water states, and the effect of changing water properties was studied to optimize the reaction conditions. The effects of reaction temperature, pressure, residence time, water/glycerol ratio, and catalyst concentration on the yields and distribution of chemical products were also examined. Acrolein yield >80 mol% from both refined glycerol and crude glycerol can be achieved by controlling water properties in the sub-critical water state with the addition of sulfuric acid as a homogeneous catalyst and the formation of undesired acetaldehyde and propionaldehyde can be greatly restrained. These results provide valuable information for the production of value-added chemicals from crude glycerol.

A quick method for analyzing the chemical composition of renewable energy biomass feedstock was developed by using Fourier transform near-infrared (FT-NIR) spectroscopy coupled with multivariate analysis. The study presents the broad-based model hypothesis that a single FT-NIR predictive model can be developed to analyze multiple types of biomass feedstock. The two most important biomass feedstocks – corn stover and switchgrass – were evaluated for the variability in their concentrations of the following components: glucan, xylan, galactan, arabinan, mannan, lignin, and ash. A hypothesis test was developed based upon these two species. Both cross-validation and independent validation results showed that the broad-based model developed is promising for future chemical prediction of both biomass species; in addition, the results also showed the method's prediction potential for wheat straw.

The ability to rapidly evaluate the chemical composition of biomass feedstock for purposes of process monitoring and optimisation is useful for gauging the potential applications and value of such feedstocks. Near infrared (NIR) spectroscopy, coupled with multivariate analysis and data pretreatment, was evaluated to remove interference from physical heterogeneity that could mask chemical property responses. Pretreatment methods included standard normal variate (SNV), multiplicative scattering correction (MSC), 1st derivative with the Savitzky-Golay algorithm (1st derivative), 2nd derivative with the Savitzky-Golay algorithm (2nd derivative), extended multiplicative signal correction (EMSC) and combinations of 1st derivative/2nd derivative with SNV. Results indicated that, of these methods, EMSC was most effective for diffuse reflectance NIR analysis of lignocellulosic biomass. The EMSC-pretreated data not only best accessed the chemical similarity of the probed feedstocks in our hierarchical cluster analysis but also consistently led to the overall best prediction of the chemical composition of the biomass.

This review covers recent research and development undertaken in converting biomass (lignocelluloses, carbohydrates, waste vegetable oil and algae) to biofuels and renewable chemicals using sub- or supercritical water (SCW) as thermochemical reaction media. Applications of SCW technology in pretreating biomass for bioethanol production by fermentation and in hydrogen/methane production by gasification are not covered in this review. The focus is on research progress in understanding the conversion characteristics of model biomass compounds, such as hemicellulose, cellulose, triglycerides and, to a lesser extent, real heterogeneous biomass in SCW. Specific attention is given to promising reaction pathways and novel process development in SCW conversion of biomass and its model compounds. There are good opportunities for the use of biomass feedstocks and SCW technology in the production of liquid fuels for the transportation sector, as well as renewable chemicals for the chemical industry. However, a broad ...

Selectively catalyzed dehydration of ethanol, 1,2-propylene glycol, and glycerol on supported heteropoly acid (HPA) was studied using transient diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). Tungstosilicic acid (H4[SiW12O40] denoted as H4SiW), supported on neutral mesoporous alumina as a catalyst, was studied to investigate the formation of intermediate products and desired dehydration products on the catalyst surface. Both ethylene-containing species and surface-bound carboxyl species were detected for all three alcohols. The formation of ethylene was promoted at lower temperatures while an increased reaction temperature facilitated the formation of acetate products when ethanol was used. When 1,2-propylene glycol was used, surface-bound carboxyl species were found as major intermediate products; these might have formed from propanal produced from the hydration reaction catalyzed by acid sites on HPA. Intermediate species from more complicated reactions were detected on the catalyst surface when glycerol was used, including aldehyde, surface-bound carboxyl species, and alkene species. The results indicated that acid dehydration might be facilitated either by the addition of water or lowering the reaction temperature. The work provides insight into reaction pathways for bio-polyols, and therefore is informative for designing cost-effective and efficient chemical catalysis systems for the conversion of bio-renewables.

A high-pressure homogenization (HPH) technique was used to improve the physicochemical properties and storage stability of switchgrass bio-oil. The viscosity, ethanol-insoluble fraction, and mass average molecular weight (Mw) of the bio-oil decreased significantly, and particle size became smaller after HPH processing; however, no significant changes were detected in heating value, water content, density, pH value, or ash content. The bio-oil's chemical composition changed after HPH: amounts of some compounds (furfural, levoglucosan, diethoxymethyl acetate, and lignin-derived compounds) increased, while others (acetic acid and 1,2-ethanediol) decreased. The homogenization processing remarkably improved switchgrass bio-oil stability: the viscosity of bio-oil homogenized at 100 MPa increased by only 13.9% after storage at 40 °C for 60 days, whereas that of unhomogenized oil increased 56% after the same storage period. The operating cost was very modest at only $0.0102/L for bio-oil HPH processing at 100 MPa.

The reaction characteristics of switchgrass conversion in subcritical water were investigated using a batch reactor under conditions of rapid rising to 250–350 °C and pressure of 20 MPa, with reaction times varying from 1–300 s. The effects of temperature and reaction time on product distribution and yields of chemical products were investigated. High conversion of switchgrass (90 wt.% on dry biomass basis) can be obtained in less than 60 s under a relative lower reaction temperature of 350 °C, compared with that in a switchgrass flash pyrolysis process where switchgrass conversion achieves only 58.9–78.8 wt.% in temperature range of 450–550 °C. The yield of water solubles (WS) can reach 37 wt.% after reaction for 1 s at 250 °C. The increases in temperature and reaction time lead to increases of the biomass conversion and the yield of gas, while WS yield decreases by secondary decomposition reactions. Many lignin-derived compounds were identified by GC-MS analysis and could well be recovered in methanol solubles (MS). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analysis of methanol insolubles (MI) indicated that the lignocellulosic matrix could be significantly decomposed, and no char formation was observed, while many lignin structures were left in the MI products. These results provide important information for recovering value-added chemicals from energy crops and biomass waste.

Medium density fiberboard is widely used with increasing tendency in North America, particularly in the furniture sector, including door skin and cabinets. Sorption property is one of the most important factors for quality judgment. This study will present water vapor sorption behavior of fibers in the range of varying relative humidity from 11% to 89% as affected by steam pressure of thermomechanical refining in small-scale measurement. A 54-year-old loblolly pine tree was refined at 2 to 18 bar of steam pressure. Fiber properties were determined by scanning electron microscope, dynamic contact angle analyzer, wide angle X-ray diffractometer, and water activity meter. The results showed that steam pressure has a dramatic effect on sorption behavior and surface properties of the refined fiber. In conclusion, a higher rate of sorption was found in juvenile fiber at low steam pressure. Higher water activity and lower crystallinity was found at low steam pressure. The sorption isotherm of refined fiber was fitted very well by the Hailwood-Horrobin model.

To determine how to triage patients with a follicular neoplasm (FN), without nuclear atypia reported by fine-needle aspiration, on the basis of risk factors.The age, sex, tumor size, and cell type of 397 patients who underwent thyroidectomy for follicular carcinoma (FC) or follicular adenoma between 1991 and 2001 were analyzed statistically. The likelihood ratio and probability of FC for various combinations of tumor size, sex, and cell type were estimated with use of Bayes' theorem.FC was significantly associated with tumor size2.1 cm (P = 0.048), male sex (P = 0.0007), and Hürthle cell type (P0.0001). The mean size of minimally invasive FC was significantly smaller (2.9 cm versus 4.8 cm; P = 0.004) and the mean patient age was significantly younger (47.6 years versus 61.0 years; P = 0.003) than for widely invasive FC. The lowest probability (0.31%) for FC was in female patients with a small (or = 2.1 cm) micro-follicular FN reported by a cytopathology practice with 10% accuracy of true FN at surgical intervention, whereas the highest probability (29.5%) for FC was in male patients with a large (2.1 cm) Hürthle cell neoplasm reported by a cytopathology practice with 70% accuracy of true FN at surgical intervention.Although an estimate of probability for FC based on age, sex, thyroid nodule size, and cell type is provided in this study for patients diagnosed with FN without nuclear atypia on fine-needle aspiration, the variability of the accuracy in cytopathology practice makes it difficult to change the current treatment paradigm, which requires carefully planned prospective studies with long-term follow-up.

In this paper, fractionated bio-char, a carbonaceous co-product from bio-fuel production, is utilized as an asphalt modifier. Laboratory testing was conducted to evaluate the modification effect of bio-char on asphalt cement and mixture. The bio-char used in this study was derived from switch grass and produced through a fast pyrolysis method. The binder samples, made by incorporating bio-char into one commonly used asphalt binder in the U.S., were tested for their rheological characteristics, rutting, and fatigue performance. It was found that bio-char was capable of significantly increasing the rutting resistance of the asphalt binder. The fatigue and cracking resistance was little affected by modification. The modified hot mix asphalt (HMA) mixture showed better resistance in rutting, moisture damage and cracking.