Search Results (9)

In this work, Eucalyptus grandis sawdust was subjected to steam explosion as the first step in cellulosic ethanol production within a biorefinery approach. The effect of the moisture content in the eucalypt sawdust (8 and 50%) and pretreatment process variables, such as temperature and residence time, were evaluated along with the influence of the water washing of steam-exploded solids on enzymatic hydrolysis and C6 fermentation yields. All other process streams were characterized to evaluate the recovery yield of valuable co-products. A recovery of nearly 100% glucans in the solid fraction and 60% xylans in the liquid fraction, mainly as partially acetylated oligomers, was obtained. The best enzymatic hydrolysis efficiencies (66–67%) were achieved after pretreatment at 205 °C for 10 min. The washing of pretreated sawdust with water improved the hydrolysis efficiencies and ethanol production yields by 10% compared to the unwashed pretreated solids under the same experimental condition. The highest ethanol yields were achieved after pretreatment of the sawdust with an 8% moisture content at 205 °C for 10 min, enzymatic hydrolysis at 13 wt% total solids with 25 FPU/g glucans, and fermentation with S. cerevisiae PE-2. In this case, 227 L ethanol and 40 kg total xylose (including xylo-oligomers) were obtained per ton of dry eucalypt sawdust. Full article

Background: Some data support that health care workers (HCWs) must have sufficient and good quality personal protective equipment (PPE) and the necessary training to manage COVID patients to avoid contagion that can lead to death. The objective of this study was to determine the relationship between biosafety on the biological risks of SARS-CoV-2 and risks of fatigue, anxiety, or depression in health workers who care for patients in COVID hospitals, from September 2020 to August 2021. Material and methods: The questionnaire used in this study (Q6S64I) consisted of 6 spheres: Sociodemographic aspects, working conditions; Personal Protection Equipment; safety and health; training and knowledge about COVID-19, the form of transport, and personal health conditions. The answers were online. The Goldberg questionnaire (EADG) measures anxiety and depression, and the questionnaire measures fatigue (Barrientos-Gutiérrez et al.) (PSSF). Results: In total, 76.5% of the HCWs were doctors, 25.2% worked in the emergency services, 79.3% received PPE from their institution, 82.9% cared for COVID-19 patients, and 27.9% tested positive for COVID-19. The PPE provided by the employer was 80%, but the quality was deficient, insufficient, and associated with a relative risk of 4.6. A total of 99% acquired better PPE on their own. The exposure to COVID-19 and the surgical mask provided by the institution had an associated relative risk of 2.8 for the HCWs. A total of 39% of the HCWs reported being calm. Conclusions: PPE, risk exposure, and safety at work were significantly associated with drowsiness and heaviness, difficulty concentrating, anxiety, and depression. Full article

In concrete structures, replacing conventional steel bars with high-strength steel reinforcement (HSSR) can effectively save the use of materials. However, the deformation properties and strength dispersion of HSSR are different from those of conventional steel reinforcement, which restricts or conservatively uses them in practical applications. For example, the partial safety factor of HRB500 grade steel bars (the yield strength is 500 MPa) in guideline GB50010-2010 is larger than that of conventional steel bars, and there is no relevant guidance for HRB600 grade steel bars (the yield strength is 600 MPa). Based on this, this paper will propose the limit state design method of high-strength steel reinforced concrete beam (HSSRCB) based on reliability analysis, which is convenient for the popularization and use of HSSR. Firstly, the flexural performance test of HSSRCBs was introduced, and the flexural capacity of HSSRCB was analyzed based on the existing prediction model. Second, a sectional numerical analysis model was established, where the section was discretized into several points, and then the curvature was gradually increased to obtain the corresponding bending moment through integration. A large number of samples were calculated to obtain statistical characteristics of the error of prediction model. Then, the limit state functions were established for two kinds of format, including partial safety factor format (PSSF) and resistance reduction factor format (RRFF), respectively, and the reliability of HSSRCBs was analyzed based on Monte Carlo simulation. Finally, the recommended values of partial safety factor of material and reduction factor of bearing capacity were proposed, in which the design strength of HRB500 and HRB600 reinforcement was 454 MPa and 545 MPa for PSSF, respectively, and the resistance reduction factor for the flexural capacity of HSSRCB was 0.8 and 0.75 for RRFF, respectively. Full article

Sweet sorghum bagasse (SSB) provides a raw material rich in polysaccharides that can be converted into biofuel and other high-value-added bioproducts under the biorefinery concept. The aim of this study was to evaluate the effect of hydrothermal pretreatment on the availability of SSB fermentable sugars for bioethanol production, considering the energy balance of the process. For this, the biomass was subjected to one process, pre-saccharification simultaneous and fermentation (PSSF). Previously, the temperature, time, and particle size effect were determined, as well as the enzymatic load for the more significant release of monomeric sugars. It was observed that the increase in the pretreatment severity, defined by the severity factor [log(R_o)], resulted in a more significant release of sugar and energy consumption. In the PSSF, bioethanol production was 22.17 g/L, with a total energy consumption of 2.46 MJ/g of processed biomass, of which 79.14% was by concept of electricity. Full article

Background: This paper aimed to explore the associations between maternal representations of attachment evaluated during pregnancy, pre and postnatal maternal depression, parenting stress and child’s attachment at 15 months after childbirth. Methods: Mothers (n = 71), and their infants participated in a longitudinal study of maternal attachment, pre and postnatal depression, parenting stress and child attachment. Adult Attachment Interview (AAI) was conducted between 24 and 26 weeks of pregnancy (Time 1), depression was assessed using the Edinburgh Perinatal Depression Scale (EPDS) (at Time 1 and 6 months after childbirth, i.e., Time 2), parenting stress was assessed using the Parenting Stress Index—Short Form (PS-SF) (at Time 2) and the Strange Situation Procedure (SSP) at child’s 15 months of age (Time 3). Results: Free-autonomous maternal classification of attachment increases the likelihood of secure child classification in her offspring, while decreases that of avoidance and ambivalence. Insecure maternal representation of attachment evaluated during pregnancy and higher levels of parenting stress at six months after childbirth was associated with higher rates of infant insecure attachment at 15 months. Conclusions: Our study validates the importance of considering maternal representations of attachment crucial in determining the quality of the caregiving environment, thereby the healthy development of children, despite the presence of other contextual risk. Full article

A new biorefinery concept is proposed that integrates the novel LX-Pretreatment with the fermentative production of L-(+)-lactic acid. Lignocellulose was chosen as a substrate that does not compete with the provision of food or feed. Furthermore, it contains lignin, a promising new chemical building material which is the largest renewable source for aromatic compounds. Two substrates were investigated: rye straw (RS) as a residue from agriculture, as well as the fibrous digestate of an anaerobic biogas plant operated with energy corn (DCS). Besides the prior production of biogas from energy corn, chemically exploitable LX-Lignin was produced from both sources, creating a product with a low carbohydrate and ash content (90.3% and 88.2% of acid insoluble lignin). Regarding the cellulose fraction of the biomass, enzymatic hydrolysis and fermentation experiments were conducted, comparing a separate (SHF), simultaneous (SSF) and prehydrolyzed simultaneous saccharification and fermentation (PSSF) approach. For this purpose, thermophilic B. coagulans 14-300 was utilized, reaching 38.0 g L⁻¹ LA in 32 h SSF from pretreated RS and 18.3 g L⁻¹ LA in 30 h PSSF from pretreated DCS with optical purities of 99%. Full article

Simultaneous saccharification and fermentation (SSF) and pre-hydrolysis with SSF (PSSF) were used to produce hydrogen from the biomass of Chlorella sp. SSF was conducted using an enzyme mixture consisting of 80 filter paper unit (FPU) g-biomass⁻¹ of cellulase, 92 U g-biomass⁻¹ of amylase, and 120 U g-biomass⁻¹ of glucoamylase at 35 °C for 108 h. This yielded 170 mL-H₂ g-volatile-solids⁻¹ (VS), with a productivity of 1.6 mL-H₂ g-VS⁻¹ h⁻¹. Pre-hydrolyzing the biomass at 50 °C for 12 h resulted in the production of 1.8 g/L of reducing sugars, leading to a hydrogen yield (HY) of 172 mL-H₂ g-VS⁻¹. Using PSSF, the fermentation time was shortened by 36 h in which a productivity of 2.4 mL-H₂ g-VS⁻¹ h⁻¹ was attained. To the best of our knowledge, the present study is the first report on the use of SSF and PSSF for hydrogen production from microalgal biomass, and the HY obtained in the study is by far the highest yield reported. Our results indicate that PSSF is a promising process for hydrogen production from microalgal biomass. Full article

Cotton stalks (CS) are considered a good candidate for fuel-ethanol production due to its abundance and high carbohydrate content, but the direct conversion without pretreatment always results in extremely low yields due to the recalcitrant nature of lignocelluloses. The present study was undertaken to investigate the effect of various chemical and physicochemical pretreatment methods, i.e., alkali, microwave-assisted acid, organosolv, hydrothermal treatment, and sequentially organosolv and hydrothermal pretreatment, on chemical composition of CS and subsequent ethanol production applying pre-hydrolysis and simultaneous saccharification and fermentation (PSSF) at high solid loading. The best results in terms of ethanol production were achieved by the sequential combination of organosolv and hydrothermal pretreatment (32.3 g/L, using 15% w/v substrate concentration and 6 h pre-hydrolysis) with an improvement of 32% to 50% in ethanol production compared to the other pretreatments. Extending pre-hydrolysis time to 14 h and increasing substrate concentration to 20% w/v, ethanol production reached 47.0 g/L (corresponding to an ethanol yield of 52%) after 30 h of fermentation. Full article

For targets with complex motion, such as ships fluctuating with oceanic waves and high maneuvering airplanes, azimuth echo signals can be modeled as multicomponent quadratic frequency modulation (QFM) signals after migration compensation and phase adjustment. For the QFM signal model, the chirp rate (CR) and the quadratic chirp rate (QCR) are two important physical quantities, which need to be estimated. For multicomponent QFM signals, the cross terms create a challenge for detection, which needs to be addressed. In this paper, by employing a novel multi-scale parametric symmetric self-correlation function (PSSF) and modified scaled Fourier transform (mSFT), an effective parameter estimation algorithm is proposed—referred to as the Two-Dimensional product modified Lv’s distribution (2D-PMLVD)—for QFM signals. The 2D-PMLVD is simple and can be easily implemented by using fast Fourier transform (FFT) and complex multiplication. These measures are analyzed in the paper, including the principle, the cross term, anti-noise performance, and computational complexity. Compared to the other three representative methods, the 2D-PMLVD can achieve better anti-noise performance. The 2D-PMLVD, which is free of searching and has no identifiability problems, is more suitable for multicomponent situations. Through several simulations and analyses, the effectiveness of the proposed estimation algorithm is verified. Full article