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1.
Bioresour Technol ; 299: 122625, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31881437

RESUMO

The production of high-purity xylobiose from lignocellulose is an expensive and tedious process. In this work, the production of xylobiose from enzymatic hydrolysis of alkaline oxidation pretreated sugarcane bagasse was investigated. Furthermore, a simple process for the separation of xylobiose from enzymatic hydrolysate by activated carbon absorption, water washing, and ethanol-water desorption was developed. Under the optimized separation conditions, 96.77% xylobiose was adsorbed at 16% activated carbon loadings. Moreover, xylose and acetate could not be detected after washing by 3-fold volume of water. Xylobiose with 80.16% yield was eluted by 5-fold volume of 5% (v/v) ethanol-water. The reusability of activated carbon was evaluated by 5 cycles of adsorption-desorption process, suggesting that the activated carbon exhibited good reusability. The separated xylobiose sample with high-purity (97.29%) was confirmed by HPLC, ESI-MS, and NMR. Overall, this study provided a low-cost and robust technology for the production and separation of high-purity xylobiose from lignocellulose.


Assuntos
Saccharum , Celulose , Dissacarídeos , Hidrólise
2.
Prep Biochem Biotechnol ; 49(6): 597-605, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30929602

RESUMO

A simple and accurate Nile Red fluorescent method was built to evaluate the lipid content of three different oleaginous yeasts by one standard curve. The staining of cells can be observed clearly by laser scanning confocal microscope, showing that Nile Red can enter into the cells of oleaginous yeasts easily. A series of conditions such as pretreating temperature, cell suspension concentration (OD600), staining time, Nile Red concentration and the type of suspension solvent were learnt systematically to obtain the optimal process parameters for Nile Red staining. After optimization, the fitting curve of Nile Red fluorescent method was established under suitable conditions (pretreating temperature: 50 °C, OD600: 1.0; staining time: 5 mins; Nile Red concentration: 1.0 µg/mL; suspension solvent: PBS) and it had a suitable correlation coefficient (R2 = 0.95) for lipid content measurement of different oleaginous yeasts. By this study, the possibility of lipid content determination of different oleaginous yeasts by one fitting curve can be proven and this will improve the efficiency of researches related to microbial lipid production.


Assuntos
Corantes Fluorescentes/química , Lipídeos/análise , Microscopia Confocal/métodos , Oxazinas/química , Leveduras/química , Cryptococcus/química , Lipomyces/química , Coloração e Rotulagem/métodos , Temperatura Ambiente , Trichosporon/química
3.
Bioresour Technol ; 283: 191-197, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30908983

RESUMO

Elephant grass (Pennisetum purpureum) acid hydrolysate was used as substrate for anaerobic digestion for the first time. Within short period (ten days), the organic materials (sugars and organic acids) in the elephant grass hydrolysate could be utilized efficiently for stable biogas production that the COD removal, biogas yield, and CH4 content were 91.3 ±â€¯2.0%, 0.561 ±â€¯0.014 m3/kg COD consumption, and 68.1 ±â€¯4.6%, respectively throughout this bioprocess. During anaerobic digestion, almost no volatile fatty acids (VFAs) was accumulated (merely <0.1 g/L acetic acid was found) and the outlet pH was very stable (7.3 ±â€¯0.1). Meanwhile, the furans including furfural and 5-hydroxymethylfurfural (HMF) existing in the inlet substrate could be degraded. After anaerobic digestion, the outlet effluent was treated by combination of Fe-C micro-electrolysis and Fenton reaction to remove 93.1% of residual COD and 98.6% of color. Considering the performance, cost, operation, and environmental influence, this technology is suitable for industrial treatment of waste elephant grass.


Assuntos
Biocombustíveis , Pennisetum/metabolismo , Anaerobiose , Reatores Biológicos , Ácidos Graxos Voláteis/metabolismo , Metano/metabolismo
4.
Sci Total Environ ; 663: 447-452, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30716636

RESUMO

Wastewater treatment is one important issue for turpentine plant and more wastewater generated by greater turpentine processing will prevent its further development. To solve this issue without extra place and new equipment, one industrial system for reuse and treatment of turpentine processing wastewater was introduced for the first time. For wastewater reuse, the technology was simple and easy to control that after neutralization by lime and absorption with activated carbon (optional, mostly not necessary), the wastewater could be reused for turpentine processing. After reuse, the wastewater was further treated by a biological system. During long-term application of wastewater reuse in this plant, it showed little influence on the products performance (mainly acid value) and final wastewater COD. Base on above advantages, the plant could decide when for wastewater drainage, and thus the amount of wastewater was reduced greatly. For the biological treatment, the COD of wastewater could be degraded to suitable level stably and the wastewater after treatment could be applied for daily life in the plant. Overall, considering the cost, operation, and performance, the whole system shows great potential and possibility of industrial application and therefore can be applied widely in the turpentine processing industry.

5.
Carbohydr Polym ; 208: 421-430, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30658820

RESUMO

Superabsorbent was synthesized from bacterial cellulose (BC) generated by in situ fermentation on bentonite inorganic gel (BIG). For BIG preparation, the effect of sodium agent's type and content, temperature and time of sodium-modification, and gelling agent's type and content on the viscosity of BIG were learned to optimize the synthesis process. For polymerization, the effect of different factors including ratio of monomer to substrate (modified BC from in situ fermentation), content of initiator and crosslinker, monomer neutralization degree, reaction temperature and time on the performance of composite (superabsorbent) synthesized were analyzed. Under optimal condition, the composite showed good water absorption, salts absorption, and water retention capacity. The original bentonite, sodium-based bentonite, BIG and composite structure was characterized by X-ray fluorescence (XRF), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA), and the characterization partly explained the performance of water absorption and thermal stability of the composite. Overall, this study provides one method for superabsorbent synthesis from low-cost and natural resources.


Assuntos
Bactérias/classificação , Celulose/metabolismo , Argila/química , Bentonita/química , Celulose/química , Fermentação , Água/química
6.
Bioresour Technol ; 275: 345-351, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30597396

RESUMO

High chemical input is required for enzymatic production of xylo-oligosaccharides (XOS) using xylan extracted from lignocellulosic biomass. In this study, enzymatic hydrolysis of alkaline oxidation (AO) treated sugarcane bagasse (SCB) directly for the production of XOS was conducted. The effect of AO pretreatment on the chemical compositions and hydrolytic properties of SCB was investigated. The AO pretreatment conditions with low chemical input for the production of XOS were optimized by orthogonal design. Stepwise enzymatic hydrolysis of AO pretreated SCB with xylanase and cellulase produced XOS (1.78 g/L), meanwhile, the cellulose conversion increased from 84.97% to 91.51% compared with directly enzymatic hydrolysis using cellulase. HPLC-UV and MALDI-TOF-MS analysis indicated that the obtained XOS products were mainly composed of xylobiose and xylose with a small amount of arabinose/4-O-methylglucuronic acid substituted xylotriose and xylotetraose. The proposed strategy for the co-production of functional XOS and fermentable sugars from SCB showed potential of industrial application.


Assuntos
Celulose/metabolismo , Oligossacarídeos/biossíntese , Saccharum/metabolismo , Açúcares/metabolismo , Álcalis , Biomassa , Fermentação , Hidrólise , Oxirredução
7.
Mater Sci Eng C Mater Biol Appl ; 96: 402-411, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30606548

RESUMO

Intensive efforts have been employed in modifying biomedical membranes. Among them, blending is recognized as a simple method. However, the conventional blending materials commonly lead to an insufficient modification, which is mainly caused by the poor miscibility between the blending materials and the matrixes, the elution of the hydrophilic materials from the matrixes during the use and storage, and the insufficient surface enrichment of the blending materials. Aiming to solve the abovementioned disadvantages, we developed novel polyethersulfone/poly(acrylic acid-co-N-vinyl-2-pyrrolidone) networked submicrogels (PES/P(AA-VP) NSs), which were blended with PES to enhance the antifouling properties, antibacterial adhesion and haemocompatible properties of PES membranes. As results, the PES/P(AA-VP) NSs showed good miscibility with the PES matrix, and hydrophilic submicrogels would enrich onto the membrane surface during the phase inversion process due to the surface segregation. The entanglement between the PES matrix and the networked submicrogels would effectively limit the elution of the submicrogels. In conclusion, the modified PES membranes prepared by blending with the PES/P(AA-VP) NSs might draw great attention for the application in haemodialysis fields.


Assuntos
Antibacterianos , Aderência Bacteriana/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Teste de Materiais , Membranas Artificiais , Polímeros , Staphylococcus aureus/crescimento & desenvolvimento , Sulfonas , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Géis , Humanos , Camundongos , Polímeros/química , Polímeros/farmacologia , Sulfonas/química , Sulfonas/farmacologia
8.
Appl Biochem Biotechnol ; 188(3): 585-601, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30552624

RESUMO

An adsorption resin CX-6 was synthesized and used for acid soluble lignin (ASL) removal from sugarcane bagasse hydrolysate (SCBH). The adsorption conditions of pH value, amount of adsorbent, initial ASL concentration, and temperature on ASL adsorption were discussed. The results showed the adsorption capacity of ASL was negatively affected by increasing temperature, solution pH, and adsorbent dose, and was positively affected by increasing initial concentration. The maximum adsorption capacity of ASL was 135.3 mg/g at initial ASL concentration 6.46 g/L, adsorption temperature 298 K, and pH 1. Thermodynamic study demonstrated that the adsorption process was spontaneous and exothermic. Equilibrium and kinetics experiments were proved to fit the Freundlich isotherm model and pseudo-second-order model well, respectively. Fermentation experiment showed that the SCBH after combined overliming with resin adsorption as fermentation substrate for microbial lipid production by Trichosporon cutaneum and Trichosporon coremiiforme was as better as that of SCBH by combined overliming with active charcoal adsorption, and more efficient than that of SCBH only by overliming. Moreover, the regeneration experiment indicated that the CX-6 resin is easy to regenerate and its recirculated performance is stable. In conclusion, our results provide a promising adsorbent to detoxify lignocellulose hydrolysate for further fermentation.


Assuntos
Ácidos/química , Lignina/isolamento & purificação , Lipídeos/biossíntese , Saccharum/química , Adsorção , Fermentação , Concentração de Íons de Hidrogênio , Hidrólise , Lignina/química , Microscopia Eletrônica de Varredura , Solubilidade , Temperatura Ambiente , Termodinâmica , Trichosporon/metabolismo
9.
Materials (Basel) ; 11(10)2018 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-30250001

RESUMO

Gel polymer electrolyte (GPE) is widely considered as a promising safe lithium-ion battery material compared to conventional organic liquid electrolyte, which is linked to a greater risk of corrosive liquid leakage, spontaneous combustion, and explosion. GPE contains polymers, lithium salts, and liquid electrolyte, and inorganic nanoparticles are often used as fillers to improve electrochemical performance. However, such composite polymer electrolytes are usually prepared by means of blending, which can impact on the compatibility between the polymer and filler. In this study, the hybrid copolymer poly (organic palygorskite-co-methyl methacrylate) (poly(OPal-MMA)) is synthesized using organic palygorskite (OPal) and MMA as raw materials. The poly(OPal-MMA) gel electrolyte exhibits an ionic conductivity of 2.94 × 10-3 S/cm at 30 °C. The Li/poly(OPal-MMA) electrolyte/LiFePO4 cell shows a wide electrochemical window (approximately 4.7 V), high discharge capacity (146.36 mAh/g), and a low capacity-decay rate (0.02%/cycle).

10.
Sensors (Basel) ; 18(10)2018 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-30249024

RESUMO

This paper proposes a way for drift compensation in electronic noses (e-nose) that often suffers from uncertain and unpredictable sensor drift. Traditional machine learning methods for odor recognition require consistent data distribution, which makes the model trained with previous data less generalized. In the actual application scenario, the data collected previously and the data collected later may have different data distributions due to the sensor drift. If the dataset without sensor drift is treated as a source domain and the dataset with sensor drift as a target domain, a domain correction based on kernel transformation (DCKT) method is proposed to compensate the sensor drift. The proposed method makes the distribution consistency of two domains greatly improved through mapping to a high-dimensional reproducing kernel space and reducing the domain distance. A public benchmark sensor drift dataset is used to verify the effectiveness and efficiency of the proposed DCKT method. The experimental result shows that the proposed method yields the highest average accuracies compared to other considered methods.

11.
J Altern Complement Med ; 24(11): 1051-1062, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30124323

RESUMO

BACKGROUND: Tanreqing injection (TRQ) is often used in the treatment of pulmonary infection in patients with tuberculosis (TB). But its efficacy and safety are still unclear; to further reveal its efficacy and safety, the authors systematically evaluated all relevant trials. METHODS: The authors searched published trials using the search strategy as (Tanreqing OR "Tanreqing injection") AND ("Tuberculosis" [MeSH] OR Tuberculosis OR TB) in Embase, PubMed, CNKI, VIP, Wanfang Database, CBM and CENTRAL, and ongoing trials in Chinese and U.S. clinical trials and World Health Organization International Clinical Trials Registry Platform (WHO-ICTRP) (established to January 2017). The authors evaluated the methodological bias risk of all included trials using the Cochrane evaluation handbook of randomized controlled trials (RCTs) (5.1.0), extracted data following the PICO principles, and synthesized the data using meta-analysis. RESULTS: Twenty-six RCTs involving 2404 patients were included. In TRQ alone versus antibiotics, the merged risk ratio (RR) values and their confidence interval (95% CI) of meta-analysis for overall efficacy, lesion absorption, and bacterial clearance were as follows: 1.05 (0.99-1.10), 0.98 (0.89-1.08), and 1.36 (1.09-1.70). All differences were not statistically significant. In TRQ plus antibiotics versus antibiotics, the RR values and their 95% CI of overall efficacy, lesion absorption, and bacterial clearance were as follows: 1.17 (1.10-1.25), 1.24 (1.11-1.38), and 1.61 (1.36-1.90). All differences were statistically significant. Except for the bacterial clearance, sensitivity analyses showed that the overall efficacy had good stability. CONCLUSIONS: TRQ may have the same overall efficacy as antibiotics in pulmonary infection in patients with TB. TRQ plus antibiotics may improve the clinical efficacy. TRQ may have synergistic effect to antibiotics through bacteriostatic activity and eliminating inflammatory mediators. Its antibacterial activity may be better than some antibiotics and does not increase adverse drug reaction. But all these need new evidences for further investigation.


Assuntos
Antibacterianos , Medicamentos de Ervas Chinesas , Tuberculose Pulmonar/tratamento farmacológico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/efeitos adversos , Antibacterianos/uso terapêutico , Medicamentos de Ervas Chinesas/efeitos adversos , Medicamentos de Ervas Chinesas/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto Jovem
12.
J Colloid Interface Sci ; 532: 680-688, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30121520

RESUMO

Ion exchange materials show great advantages in water purification, food industry, pharmaceutical industry, etc. However, the ion exchange capacities of ion exchange materials, especially for anion-exchange materials, at present are still relatively low. Hydrogels own abundant functional groups and show high hydrophilicity, and thus are recognized as high-potential ion exchange materials, but may deform and even crush in use due to their low mechanical strength and unavoidable swelling behavior. In this study, inspired by the root-soil structure, novel poly(methacryloxyethyltrimethyl ammonium chloride) composite hydrogel microspheres with ultrahigh ion exchange capacity (more than 3.8 meuqiv/g), low swelling ratio (less than 1.5 g/g under pH = 7), and ultrahigh mechanical strength (more than 28.1 MPa) were prepared. The microspheres showed efficient adsorption for anionic dyes (1491 mg/g for methyl orange, 1693 mg/g for Congo red, and 204.7 mg/g for amaranth, respectively) and great adsorption for bilirubin (131.6 mg/g). Taken together, the hydrogel microspheres were qualified as stable and high-efficiency ion exchange materials. More importantly, the root-soil structure opens up avenues for enhancing the dimensional stability of functional hydrogels.

13.
Sensors (Basel) ; 18(1)2018 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-29342897

RESUMO

The replica strategy in distributed cache can effectively reduce user access delay and improve system performance. However, developing a replica strategy suitable for varied application scenarios is still quite challenging, owing to differences in user access behavior and preferences. In this paper, a replication strategy for spatiotemporal data (RSSD) based on a distributed caching system is proposed. By taking advantage of the spatiotemporal locality and correlation of user access, RSSD mines high popularity and associated files from historical user access information, and then generates replicas and selects appropriate cache node for placement. Experimental results show that the RSSD algorithm is simple and efficient, and succeeds in significantly reducing user access delay.

14.
Polymers (Basel) ; 10(7)2018 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-30960627

RESUMO

Cellulose-based superabsorbent was synthesized by bacterial cellulose (BC) grafting acrylic acid (AA) in the presence of N,N'-methylenebisacrylamide (NMBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The influence of different factors on composite synthesis, including the weight ratio of the monomer to BC, initiator content, crosslinker content, AA neutralization degree, reaction temperature, and reaction time on the water absorbency of the composite, were systematically learned. Under the optimized conditions, the maximum water absorbency of the composite was 322 ± 23 g/g distilled water. However, the water absorbency was much less for the different salt solutions and the absorption capacity of the composite decreased as the concentration of the salt solutions increased. The pH value had a significant influence on water absorption performance, and with the increase of temperature, the water retention rate of the composite decreased. Additionally, the structure of this composite was characterized with nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results of NMR and FT-IR provided evidence that the composite was synthesized by BC and AA, and the microstructure showed that it had good performance for water absorption. In addition, the composite possessed suitable thermal stability, and that it could be used in a few high-temperature environments. Overall, this composite is promising for application in water absorption.

15.
J Agric Food Chem ; 65(51): 11237-11242, 2017 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-29200277

RESUMO

In this study, a fast startup of semi-pilot-scale anaerobic digestion of food waste acid hydrolysate for biogas production was carried out for the first time. During the period of fast startup, more than 85% of chemical oxygen demand (COD) can be degraded, and even more than 90% of COD can be degraded during the later stage of anaerobic digestion. During this anaerobic digestion process, the biogas yield, the methane yield, and the CH4 content in biogas were 0.542 ± 0.056 m3/kgCOD consumption, 0.442 ± 0.053 m3/kgCOD consumption, and 81.52 ± 3.05%, respectively, and these values were high and stable. Besides, the fermentation pH was very stable, in which no acidification was observed during the anaerobic digestion process (outlet pH was 7.26 ± 0.05 for the whole anaerobic digestion). Overall, the startup of this anaerobic digestion can be completed in a short period (the system can be stable 2 days after the substrate was pumped into the bioreactor), and anaerobic digestion of food waste acid hydrolysate is feasible and attractive for industrial treatment of food waste and biogas production.


Assuntos
Biocombustíveis/análise , Metano/análise , Resíduos/análise , Anaerobiose , Reatores Biológicos , Projetos Piloto , Esgotos/química
16.
Sensors (Basel) ; 17(11)2017 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-29149075

RESUMO

Clustering is an effective topology control method in wireless sensor networks (WSNs), since it can enhance the network lifetime and scalability. To prolong the network lifetime in clustered WSNs, an efficient cluster head (CH) optimization policy is essential to distribute the energy among sensor nodes. Recently, game theory has been introduced to model clustering. Each sensor node is considered as a rational and selfish player which will play a clustering game with an equilibrium strategy. Then it decides whether to act as the CH according to this strategy for a tradeoff between providing required services and energy conservation. However, how to get the equilibrium strategy while maximizing the payoff of sensor nodes has rarely been addressed to date. In this paper, we present a game theoretic approach for balancing energy consumption in clustered WSNs. With our novel payoff function, realistic sensor behaviors can be captured well. The energy heterogeneity of nodes is considered by incorporating a penalty mechanism in the payoff function, so the nodes with more energy will compete for CHs more actively. We have obtained the Nash equilibrium (NE) strategy of the clustering game through convex optimization. Specifically, each sensor node can achieve its own maximal payoff when it makes the decision according to this strategy. Through plenty of simulations, our proposed game theoretic clustering is proved to have a good energy balancing performance and consequently the network lifetime is greatly enhanced.

17.
Indian J Microbiol ; 57(4): 393-399, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29151639

RESUMO

Durian is one important tropical fruit with high nutritional value, but its shell is usually useless and considered as waste. To explore the efficient and high-value utilization of this agricultural and food waste, in this study, durian shell was simply hydrolyzed by dilute sulfuric acid, and the durian shell hydrolysate after detoxification was used for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. BC was synthesized in static culture for 10 days and the highest BC yield (2.67 g/L) was obtained at the 8th day. The typical carbon sources in the substrate including glucose, xylose, formic acid, acetic acid, etc. can be utilized by G. xylinus. The highest chemical oxygen demand (COD) removal (16.40%) was obtained at the 8th day. The highest BC yield on COD consumption and the highest BC yield on sugar consumption were 93.51% and 22.98% (w/w), respectively, suggesting this is one efficient bioconversion for BC production. Durian shell hydrolysate showed small influence on the BC structure by comparison with the structure of BC generated in traditional Hestrin-Schramm medium detected by FE-SEM, FTIR, and XRD. Overall, this technology can both solve the issue of waste durian shell and produce valuable bio-polymer (BC).

18.
Prep Biochem Biotechnol ; 47(10): 1025-1031, 2017 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-28857665

RESUMO

Biomass acid hydrolysate of oleaginous yeast Trichosporon cutaneum after microbial oil extraction was applied as substrate for bacterial cellulose (BC) production by Komagataeibacter xylinus (also named as Gluconacetobacter xylinus previously) for the first time. BC was synthesized in static culture for 10 days, and the maximum BC yield (2.9 g/L) was got at the 4th day of fermentation. Most carbon sources in the substrate (glucose, mannose, formic acid, acetic acid) can be utilized by K. xylinus. The highest chemical oxygen demand (COD) removal (40.7 ± 3.0%) was obtained at the 6th day of fermentation, and then the COD increased possibly due to the degradation of BC. The highest BC yield on COD consumption was 38.7 ± 4.0% (w/w), suggesting that this is one efficient bioconversion for BC production. The BC structure was affected little by the substrate by comparison with that generated in classical HS medium using field-emission scanning electron microscope (FE-SEM), Fourier transform infrared, and X-ray diffraction. Overall, this technology can both solve the issue of waste oleaginous yeast biomass and produce valuable biopolymer (BC).


Assuntos
Biomassa , Celulose/metabolismo , Gluconacetobacter xylinus/metabolismo , Microbiologia Industrial/métodos , Óleos/isolamento & purificação , Trichosporon/metabolismo , Ácidos/metabolismo , Análise da Demanda Biológica de Oxigênio , Fermentação , Hidrólise , Óleos/metabolismo , Resíduos Sólidos/análise , Trichosporon/química
19.
Carbohydr Polym ; 175: 199-206, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-28917857

RESUMO

Understanding the interaction mechanisms between xylan and xylan-degrading enzymes is beneficial to the efficient hydrolysis of xylan. Xylan from sugarcane bagasse (SB) was extracted and characterized. The effects of heat treatment and removal of side chains of SB xylan on the hydrolytic efficiency and synergistic action of endo-ß-1,4-xylanases (HoXyn11A and AnXyn10C), ß-xylosidases (AnXln3D), and α-l-arabinofuranosidases (AnAxh62A) were investigated. Results indicated that heat treatment of xylan can improve the hydrolytic efficiency of xylan-degrading enzymes, and it is essential for the efficient hydrolysis of xylan by HoXyn11A. The removal of arabinofuranosyl side chains of xylan by AnAxh62A before enzymatic hydrolysis reduced the hydrolytic efficiency of HoXyn11A and AnXyn10C on xylan. AnXyn10C was more efficient than HoXyn11A in hydrolysis of xylan, whereas HoXyn11A showed better synergistic action than AnXyn10C with AnAxh62A and AnXln3D in the hydrolysis of xylan. This study provides new insights on the enzymatic hydrolysis of SB into monosaccharides and xylo-oligosaccharides.


Assuntos
Celulose/química , Endo-1,4-beta-Xilanases/metabolismo , Saccharum/química , Xilanos/metabolismo , Hidrólise
20.
Proc Natl Acad Sci U S A ; 114(28): 7246-7249, 2017 07 11.
Artigo em Inglês | MEDLINE | ID: mdl-28652329

RESUMO

The amplitude of the photoacoustic effect for an optical source moving at the sound speed in a one-dimensional geometry increases linearly in time without bound in the linear acoustic regime. Here, use of this principle is described for trace detection of gases, using two frequency-shifted beams from a CO2 laser directed at an angle to each other to give optical fringes that move at the sound speed in a cavity with a longitudinal resonance. The photoacoustic signal is detected with a high-[Formula: see text], piezoelectric crystal with a resonance on the order of [Formula: see text] kHz. The photoacoustic cell has a design analogous to a hemispherical laser resonator and can be adjusted to have a longitudinal resonance to match that of the detector crystal. The grating frequency, the length of the resonator, and the crystal must all have matched frequencies; thus, three resonances are used to advantage to produce sensitivity that extends to the parts-per-quadrillion level.

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