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1.
Opt Express ; 32(6): 8623-8637, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38571117

RESUMO

In fiber-terahertz integrated communication systems, nonlinear distortion and inter-symbol interference (ISI) will degrade transmission performance. Pre-compensation is an efficient method to handle the channel distortion as it can avoid noise boosting during channel compensation and reduce receiver side signal processing algorithmic complexity at user-end (UE) considering the asymmetric access scenario. In this paper, we propose and experimentally demonstrate a neural-network (NN)-based carrier-less amplitude phase (CAP) modulated signal generation and end-to-end optimization method for a fiber-terahertz integrated communication system. The CAP signal is generated directly from quadrature amplitude modulation symbols and pre-compensated through a transmitter NN, which allows the receiver to demodulate the signal with simple linear digital signal process (DSP). In generating the CAP signal, the NN based transmitter learns a group of filters, which can generate, up-convert, and pre-compensate the signals. Based on the proposed method, a fiber-terahertz integration access system at 220 GHz is demonstrated and a sensitivity gain of 1.2 dB is achieved at a transmission speed of 50 Gbps and the forward error correction (FEC) bit error rate (BER) threshold of 1 × 10-2 compared with the baseline after 10-km fiber transmission and 1-m wireless delivering.

2.
Artigo em Inglês | MEDLINE | ID: mdl-38241100

RESUMO

With the increasing demand for data privacy, federated learning (FL) has gained popularity for various applications. Most existing FL works focus on the classification task, overlooking those scenarios where anomaly detection may also require privacy-preserving. Traditional anomaly detection algorithms cannot be directly applied to the FL setting due to false and missing detection issues. Moreover, with common aggregation methods used in FL (e.g., averaging model parameters), the global model cannot keep the capacities of local models in discriminating anomalies deviating from local distributions, which further degrades the performance. For the aforementioned challenges, we propose Federated Anomaly Detection with Noisy Global Density Estimation, and Self-supervised Ensemble Distillation (FADngs). Specifically, FADngs aligns the knowledge of data distributions from each client by sharing processed density functions. Besides, FADngs trains local models in an improved contrastive learning way that learns more discriminative representations specific for anomaly detection based on the shared density functions. Furthermore, FADngs aggregates capacities by ensemble distillation, which distills the knowledge learned from different distributions to the global model. Our experiments demonstrate that the proposed method significantly outperforms state-of-the-art federated anomaly detection methods. We also empirically show that the shared density function is privacy-preserving. The code for the proposed method is provided for research purposes https://github.com/kanade00/Federated_Anomaly_detection.

3.
Dalton Trans ; 53(2): 675-683, 2024 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-38078462

RESUMO

The use of photocatalysts based on semiconductor heterostructures for hydrogen evolution is a prospective tactic for converting solar energy. Herein, visible-light-responsive three-dimensional core-shell CoSe2/ZnIn2S4 heterostructures were successfully fabricated via in situ growth of ZnIn2S4 ultrathin nanosheets on spherical CoSe2. Without any noble metal co-catalysts, the as-prepared CoSe2/ZnIn2S4 composite achieved attractive photocatalytic hydrogen evolution activity under visible light illumination. Optimal CoSe2/ZnIn2S4 achieved a hydrogen evolution rate of 2199 µmol g-1 h-1, which was 7 times higher than that of pristine ZnIn2S4 and even exceeded that of ZnIn2S4 loaded with platinum. In this distinctive core-shell heterostructure, the presence of CoSe2 could considerably improve the ability to harvest light, quicken the charge transfer kinetics, and avoid the agglomeration of ZnIn2S4 nanosheets. Meanwhile, the experimental results demonstrated that the strong interaction between CoSe2 and ZnIn2S4 at the compact interface could appropriately boost the photogenerated electron-hole pair migration and relieve charge recombination, thus improving photocatalytic hydrogen evolution activity. This work has bright prospects in constructing noble-metal-free core-shell heterostructures for solar energy conversion.

4.
Int J Mol Sci ; 24(18)2023 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-37762587

RESUMO

The application of melatonin (MT) has been shown to improve the quality during the storage of fruits and vegetables. The primary objective of this study is to investigate the effects of MT on the quality of fresh-cut Gastrodia elata during low-temperature (4 °C) storage. The results indicated that MT treatment not only suppressed the respiratory rate and malondialdehyde content but also slowed down the decline in total acidity and total soluble solids, effectively inhibiting microbial growth and enhancing the product safety of fresh-cut G. elata. The treatment with MT reduced the superoxide anions and hydrogen peroxide production, as well as inhibiting the activity and expression of peroxidase and polyphenol oxidase. Additionally, it led to increased activity and the expression of antioxidant-related enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase, while also resulting in elevated levels of ascorbic acid and glutathione. Furthermore, the treatment with MT induced an increase in the total phenolic and flavonoid content of fresh-cut G. elata and enhanced the activity and expression of key enzymes involved in the phenylpropanoid pathway (phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, 4-coumarate: CoA ligase). In summary, MT enhances the antioxidant capacity by activating both the ROS metabolism and phenylpropanoid pathway, thus maintaining the quality of fresh-cut G. elata.


Assuntos
Gastrodia , Melatonina , Melatonina/farmacologia , Espécies Reativas de Oxigênio , Antioxidantes , Temperatura
5.
Opt Express ; 31(10): 15239-15255, 2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37157631

RESUMO

Fiber-wireless integration has been widely studied as a key technology to support radio access networks in sixth-generation wireless communication, empowered by artificial intelligence. In this study, we propose and demonstrate a deep-learning-based end-to-end (E2E) multi-user communication framework for a fiber-mmWave (MMW) integrated system, where artificial neural networks (ANN) are trained and optimized as transmitters, ANN-based channel models (ACM), and receivers. By connecting the computation graphs of multiple transmitters and receivers, we jointly optimize the transmission of multiple users in the E2E framework to support multi-user access in one fiber-MMW channel. To ensure that the framework matches the fiber-MMW channel, we employ a two-step transfer learning technique to train the ACM. In a 46.2 Gbit/s 10-km fiber-MMW transmission experiment, compared with the single-carrier QAM, the E2E framework achieves over 3.5 dB receiver sensitivity gain in the single-user case and 1.5 dB gain in the three-user case under the 7% hard-decision forward error correction threshold.

6.
Opt Express ; 30(22): 40936-40950, 2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36299018

RESUMO

The integration of sensing and communication (ISAC) in millimeter-waves (MMW) will play an important role in future 6G applications. Photonics-based radar sensing and communication systems have the advantages of high bandwidth in terms of high-resolution sensing and high-speed data transmission and can be inherently integrated with fiber-optic networks. To support flexible application scenarios, in this paper, we proposed and experimentally demonstrated an MMW photonics-based flexible ISAC system with adaptive signal waveforms for a W-band fiber-wireless integrated network. Photonics-based W-band ISAC signals are generated by heterodyning two free-running external cavity lasers. Microwave photonics-based radar signal processing supports centralized and seamless fiber-wireless communication and sensing networks. In our proposed system, orthogonal frequency-division multiplexing (OFDM) and linear frequency modulation (LFM) signals were combined by frequency-division multiplexing to share this bandwidth. Therefore, we can adaptively allocate bandwidths to OFDM and LFM signals according to the application requirements and realize a flexible ISAC system with high-speed communication and high-resolution radar sensing. As a proof-of-concept, a flexible W-band fiber-wireless ISAC system at 96.5 GHz over 10-km fiber transmission was demonstrated, achieving adaptive access rates from 5.98 to 41.48 Gbit/s after transmission over 1-m free space, and adaptive sensing resolutions from 1.53 to 6.94 cm with the distance error after calibration less than 4 cm. The performance of both communication and sensing under different bandwidth ratios was also studied.

7.
Front Psychol ; 13: 810437, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35360596

RESUMO

The experience of loss of agency is one of the reasons for clients to go for psychotherapy. Enhancing clients' agency has been considered a fundamental factor for successful treatment in psychiatry and psychotherapy, yet few studies have investigated the interactional realization of how therapists do this in authentic psychotherapeutic encounters. Drawing on audio-recorded talk-in-interaction between clients and psychotherapists in cognitive behavioral therapy (CBT) encounters at a mental health center in China, this paper uses the method of conversation analysis to demonstrate how therapists ascribe agency positions to clients by issuing formulations of what the clients have just said. Two types of formulation were identified: affirmative formulations and challenging formulations. In the first type, the therapists highlight the positive aspect of the clients' description of their experiences and ascribe an agentic position to the clients. In the second, the therapists challenge the clients' implausible views and their non-agentic positioning of themselves. This study shows that the therapists' formulation could be employed to manage the epistemic difficulties associated with claiming knowledge about the clients' inner states and assessing their feelings. In this sense, the formulation is a robust interactional device in negotiating epistemic problems in addressing the clients' experiences and promoting their agency in therapy. However, it is noteworthy that in the challenging formulation, therapists claim privileged access to the clients' knowledge domain and challenge their prior epistemic status, which might run the risk of engendering clients' resistance.

8.
Front Plant Sci ; 12: 753261, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34759944

RESUMO

Rosa roxburghii fruit were used as research objects to study the effects of different concentrations of benzothiazole (BTH) treatment on quality parameters, reactive oxygen species (ROS) metabolism, and the phenylpropanoid pathway during storage at 4°C for 14days. Results showed that BTH effectively delayed senescence with lower decay incidence, weight loss, and lipid peroxidation level and maintained the quality with higher contents of total soluble solid (TSS) content, titratable acidity (TA) in R. roxburghii fruit. Moreover, BTH increased hydrogen peroxide (H2O2) content, superoxide anion (O2 •-) production rate, and the activities and expression of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione (GSH) reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and peroxidase (POD), and the contents of GSH and ascorbic acid (AsA), but reduced the oxidized GSH (GSSG) content. In addition, the activities and gene expression of phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate-CoA ligase (4CL) and the concentrations of flavonoids, total phenols, and lignin were significantly elevated by BTH. These findings imply that BTH can delay senescence and maintain the quality of R. roxburghii fruit by modulating ROS metabolism and the phenylpropanoid pathway under low-temperature conditions.

9.
Micromachines (Basel) ; 13(1)2021 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-35056205

RESUMO

The impact of device parameters, including AlN film thickness (hAlN), number of interdigital transducers (NIDT), and acoustic propagation direction, on the performance of c-plane AlN/sapphire-based SAW temperature sensors with an acoustic wavelength (λ) of 8 µm, was investigated. The results showed that resonant frequency (fr) decreased linearly, the quality factor (Q) decreased and the electromechanical coupling coefficient (Kt2) increased for all the sensors with temperature increasing from -50 to 250 °C. The temperature coefficients of frequency (TCFs) of sensors on AlN films with thicknesses of 0.8 and 1.2 µm were -65.57 and -62.49 ppm/°C, respectively, indicating that a reduction in hAlN/λ favored the improvement of TCF. The acoustic propagation direction and NIDT did not obviously impact the TCF of sensors, but they significantly influenced the Q and Kt2 of the sensors. At all temperatures measured, sensors along the a-direction exhibited higher fr, Q and Kt2 than those along the m-direction, and sensors with NIDT of 300 showed higher Q and Kt2 values than those with NIDT of 100 and 180. Moreover, the elastic stiffness of AlN was extracted by fitting coupling of modes (COM) model simulation to the experimental results of sensors along different directions considering Euler transformation of material parameter-tensors. The higher fr of the sensor along the a-direction than that along the m-direction can be attributed to its larger elastic stiffness c11, c22, c44, and c55 values.

10.
Bioanalysis ; 12(14): 991-1001, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32697609

RESUMO

Aim: To optimize clinical efficacy and reduce the drug-exposure-related toxicity of linezolid, whose concentrations show wide inter-variabilities, a simple and reliable quantitative assay for therapeutic drug monitoring is necessary. Results: A UHPLC-MS/MS assay has been established for determination of linezolid in human plasma and fully validated according to the US FDA guidelines. After a simple, isotope-dilluted precipitation with methanol, the analytes were separated by a straightforward isocratic mode and the MS/MS was conducted under the ESI+ mode fitted with SRM. The calibration curves proved acceptable linearity in the range of 0.1-30.0 µg/ml. Conclusion: The present assay is currently used in routine clinical practice, being applied to therapeutic drug monitoring and helps to optimize individual dosing regimens and manage adverse effects in ICU patients.


Assuntos
Cromatografia Líquida/métodos , Monitoramento de Medicamentos/métodos , Isótopos/química , Linezolida/sangue , Espectrometria de Massas em Tandem/métodos , Humanos
11.
Int J Mol Sci ; 20(6)2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30901821

RESUMO

Brunfelsia calycina flowers lose anthocyanins rapidly and are therefore well suited for the study of anthocyanin degradation mechanisms, which are unclear in planta. Here, we isolated an anthocyanin-ß-glycosidase from B. calycina petals. The MS/MS (Mass Spectrometry) peptide sequencing showed that the enzyme (72 kDa) was a ß-xylosidase (BcXyl). The enzyme showed high activity to p-Nitrophenyl-ß-d-galactopyranoside (pNPGa) and p-Nitrophenyl-ß-d-xylopyranoside (pNPX), while no activity to p-Nitrophenyl-ß-d-glucopyranoside (pNPG) or p-Nitrophenyl-ß-D-mannopyranoside (pNPM) was seen. The optimum temperature of BcXyl was 40 °C and the optimum pH was 5.0. The enzyme was strongly inhibited by 1 mM D-gluconate and Ag⁺. HPLC (High Performance Liquid Chromatography) analysis showed that BcXyl catalyzed the degradation of an anthocyanin component of B. calycina, and the release of xylose and galactose due to hydrolysis of glycosidic bonds by BcXyl was detected by GC (Gas Chromatography) /MS. A full-length mRNA sequence (2358 bp) of BcXyl (NCBI No. MK411219) was obtained and the deduced protein sequence shared conserved domains with two anthocyanin-ß-glycosidases (Bgln and BadGluc, characterized in fungi). BcXyl, Bgln and BadGluc belong to AB subfamily of Glycoside hydrolase family 3. Similar to BcPrx01, an anthocyanin-degradation-related Peroxidase (POD), BcXyl was dramatically activated at the stage at which the rapid anthocyanin degradation occurred. Taken together, we suggest that BcXyl may be the first anthocyanin-ß-glycosidase identified in higher plants.


Assuntos
Antocianinas/metabolismo , Flores/enzimologia , Glicosídeo Hidrolases/metabolismo , Solanaceae/enzimologia , Xilosidases/isolamento & purificação , Xilosidases/metabolismo , Sequência de Aminoácidos , Ativação Enzimática , Cromatografia Gasosa-Espectrometria de Massas , Regulação da Expressão Gênica de Plantas , Glicosídeo Hidrolases/química , Filogenia , Desenvolvimento Vegetal/genética , Solanaceae/classificação , Solanaceae/genética , Xilosidases/química
12.
Ultrasonics ; 91: 30-33, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30056273

RESUMO

AlN based surface acoustic wave (SAW) filters with an acoustic wavelength (λ) of 8 µm have been fabricated based on sputtered AlN films on sapphire. The acoustic velocity of 1-µm-AlN/Sapphire bilayer structure is 5536 m/s, 60% higher than that of LiNbO3. The central frequency, insertion loss, out-of-band rejection, and bandwidth of fabricated AlN based two-port type SAW filters with a delay gap of λ are 692 MHz, 25.58 dB, 35.40 dB, and 2.7 MHz, respectively. The impact of delay gap on the performance of AlN based filters have been studied experimentally. By the analysis of frequency response of SAW filters with delay gaps of λ, 15λ, and 30λ with and without time gating technique, we find that increase the delay gap of AlN based SAW resonators can improve the out-of-band rejection effectively because of the reduction of electromagnetic coupling, with a cost of a little degradation of insertion loss due to the small propagation loss of AlN/Sapphire bilayer. When the delay gap is increased from λ to 15λ, out-of-band rejection of AlN based filters is increased by 4.75 dB, while the insertion loss is only increased by 0.81 dB. When the delay gap is further increased from 15λ to 30λ, the suppression of out-of-band rejection is not obvious.

13.
J Zhejiang Univ Sci B ; 18(1): 76-78, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28070999

RESUMO

This study investigated the anticancer effect of Shenqi Fuzheng (SQFZ) injection combined with docetaxel on lung cancer cell lines of A549 and Lewis lung cancer (LLC). SQFZ injection alone cannot inhibit the vitality of lung cancer cells, but the antitumor activity of SQFZ combined with docetaxel was significantly higher than that using docetaxel alone.


Assuntos
Antineoplásicos/administração & dosagem , Medicamentos de Ervas Chinesas/administração & dosagem , Neoplasias Pulmonares/tratamento farmacológico , Taxoides/administração & dosagem , Células A549 , Animais , Carcinoma Pulmonar de Lewis/tratamento farmacológico , Linhagem Celular Tumoral , Docetaxel , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Masculino , Camundongos
14.
Eur J Drug Metab Pharmacokinet ; 42(4): 719-727, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27928655

RESUMO

BACKGROUND AND OBJECTIVES: Pueraria labata has traditionally been applied in the treatment of stroke in Chinese clinics. Puerarin is the key ingredient in it for brain protection effect. To find a superior administration route for puerarin in the treatment of ischemic cerebrovascular disease, the pharmacokinetics of puerarin based on the middle cerebral artery occlusion (MCAO) rat via different administration routes were studied and compared. METHODS: Ten rats (MCAO model) divided into two groups were treated with puerarin via intravenous and intranasal routes. Samples of brain and plasma were collected by microdialysis and tested by high-performance liquid chromatography with tandem mass spectrometric detection (HPLC-MS/MS). RESULTS: In olfactory bulb, the intranasal group got a higher C max, which was eight times higher than that of intravenous group. The AUC of puerarin were 255.96 ± 87.74 and 24.56 ± 15.50 min·µg/ml for intranasal and intravenous group, respectively. The intranasal group also got a longer T 1/2 compared with intravenous group. The drug target index (DTI) of intranasal group was up to 47.98%, which was highly improved, compared with intravenous group. CONCLUSIONS: The in vivo experiments based on the MCAO model showed that, compared with intravenous route, the bioavailability and brain-targeting of drug were highly improved via intranasal route. In pathological conditions, compared with normal rats, the AUC of puerarin in brain and DTI increased significantly.


Assuntos
Encéfalo/metabolismo , Infarto da Artéria Cerebral Média/metabolismo , Isoflavonas/administração & dosagem , Isoflavonas/farmacocinética , Vasodilatadores/administração & dosagem , Vasodilatadores/farmacocinética , Administração Intranasal , Animais , Disponibilidade Biológica , Modelos Animais de Doenças , Infarto da Artéria Cerebral Média/tratamento farmacológico , Infusões Intravenosas , Isoflavonas/sangue , Microdiálise , Ratos Sprague-Dawley , Vasodilatadores/sangue
15.
J Proteomics ; 120: 179-93, 2015 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-25779462

RESUMO

Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) is a chemical plant elicitor capable of inducing disease resistance in many crops. In this study, the climacteric fruit muskmelon (cv. Yujinxiang) was treated with BTH at 0.1g/L for assaying the changes in physiology, biochemistry and protein profile during ripening. The results showed that BTH treatment enhanced respiration rate, while reduced titratable acid content and retarded the decline of fruit firmness and ascorbic acid content. Ethylene production increased after BTH treatment at early stages of ripening, but decreased after 6days of treatment. Of the detected protein spots separated by means of 2-DE, 69 spots changed in abundance significantly after BTH treatment. Fifty-two spots out of 69 were identified using MALDI-TOF/TOF by blasting against NCBInr database. Functional classification revealed that the protein species identified were related to defense and stress responses, protein synthesis, destination and storage, energy metabolism, primary metabolism, cell structure, secondary metabolism, signal transduction and transporters. This study demonstrates an overview of major physiological, biochemical and proteomic changes in muskmelon fruit during ripening after BTH treatment and provides potentially useful information for maintaining fruit quality and delaying the ripening and senescence process. BIOLOGICAL SIGNIFICANCE: The study offers new proteomic evidences for elucidating the regulatory mechanism of muskmelon fruit ripening by BTH treatment at proteomic level, and provides a valuable reference for further research on the relationship between fruit quality and induction disease resistance in BTH-treated fruits.


Assuntos
Cucumis melo/fisiologia , Frutas/fisiologia , Proteínas de Plantas/metabolismo , Proteoma/metabolismo , Tiadiazóis/farmacologia , Cucumis melo/efeitos dos fármacos , Frutas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/fisiologia
16.
Zhongguo Zhong Yao Za Zhi ; 40(16): 3194-9, 2015 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-26790291

RESUMO

The borneol was included with ß-CD and prepared Fufang Danshen intestinal adhesion pellets. GC method for determination of borneol in Fufang Danshen intestinal adhesion pellets was established to study its in vitro dissolution and make a comparison with the Fufang Danshen tablet, in this way, the rationality of dosage form was evaluated. The first method of dissolution determination was used for determining the in vitro dissolution of borneol in Fufang Danshen intestinal adhesion pellets in artificial intestinal juice, and Fufang Danshen tablet in artificial gastric juice and intestinal juice, respectively. Result shows: the concentration of borneol in Fufang Danshen intestinal adhesion pellets and Fufang Danshen tablet was 0.79% and 0.80%, respectively. Its in vitro dissolution was nearly 70% within 12 h in Fufang Danshen intestinal adhesion pellets, and in Fufang Danshen tablet, the dissolution was about 60% within 20 min and more than 90% within 40 min, and in artificial gastric juice, was less than 20% within 40 min but more than 80% till 150 min. Research suggests that in comparison with Fufang Danshen tablet, in vitro dissolution of borneol in the Fufang Danshen intestinal adhesion pellets showed an obvious sustained release behavior. The borneol in Fufang Danshen intestinal adhesion pellets was included with ß-CD and prepared enteric preparations. To some extent, the stimulation on stomach and intestinal mucosa can be reduced and safety can be improved.


Assuntos
Canfanos/química , Química Farmacêutica/métodos , Medicamentos de Ervas Chinesas/química , Mucosa Intestinal/efeitos dos fármacos , Canfanos/efeitos adversos , Canfanos/farmacologia , Formas de Dosagem , Medicamentos de Ervas Chinesas/efeitos adversos , Medicamentos de Ervas Chinesas/farmacologia , Humanos , Mucosa Intestinal/metabolismo , Modelos Biológicos , Solubilidade
17.
J AOAC Int ; 96(6): 1239-44, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24645500

RESUMO

A single-laboratory validation study was conducted using HPLC for detecting and quantifying acetic acid, furfural, and 5-hydroxymethylfurfural (HMF) in corncob hydrolysates. A pretreatment procedure using dilute sulfuric acid was optimized for corncob hydrolysis. The final hydrolysates were analyzed by HPLC using a C18 RP column with aqueous 0.01% (v/v) H2SO4-CH3OH (95 + 5) as the mobile phase at a flow rate of 1 mL/min. The wavelengths for detecting the three compounds were changed to their optimal UV detection wavelengths at the time of elution. The wavelength detection adjustments were as follow: 205 nm (0 to 4 min); 284 nm (4 to 7 min); and 276 nm (7 to 10 min). Separation was achieved with a chromatographic run time of 10 min. The calibration curves for the three compounds had correlation coefficients (r2) > or = 99.8%. The analytical range, as defined by the calibration curves, was 0.5-10 mg/L for acetic acid, 0.4-22 mg/L for furfural, and 0.1-18 mg/L for HMF. The LODs for acetic acid, furfural, and HMF were estimated to be 0.05, 0.03, and 0.02 mg/L, respectively; the LOQs were 0.196, 0.135, and 0.074 mg/L, respectively. The RSD values for the intraday precision study ranged from 0.31 to 2.22%, and from 0.57 to 2.43% for the interday study. The mean recovery rates in all compounds were between 100.08 and 101.49%.


Assuntos
Ácido Acético/análise , Furaldeído/análogos & derivados , Furaldeído/análise , Biomassa , Calibragem , Cromatografia Líquida de Alta Pressão , Concentração de Íons de Hidrogênio , Hidrólise , Lignina/química , Reprodutibilidade dos Testes , Espectrofotometria Ultravioleta , Ácidos Sulfúricos , Gerenciamento de Resíduos , Zea mays/química
18.
Bioresour Technol ; 101(18): 7005-10, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20403687

RESUMO

To the aim of efficient utilization of both of xylose and cellulose, a laboratory xylose/cellulose fractionation and separate fermentation (XCFSF) bioethanol process was performed. Three xylose/cellulose fractionation strategies: (A) dilute sulfur acid hydrolysis and detoxification, (B) lime pretreatment and xylanase hydrolysis, (C) bio-treatment with Phanerochaete chrysosporium and xylanase hydrolysis were applied to corn cobs. As a result, the maximum xylose yields obtained from A, B and C fractionation methods were 78.47%, 57.84% and 42.54%, respectively, and 96.81%, 92.14% and 80.34% of cellulose were preserved in the corresponding solid residues. The xylose dissolved in acid and enzymatic hydrolysates was fermented to ethanol by Candida shahatae and the cellulose remaining in solid residues was converted to ethanol by simultaneous saccharification and fermentation (SSF) with Saccharomyces cerevisiae. Finally, for A, B, C fractionation methods, 70.40%, 52.87%, 39.22% of hemicellulose and 89.77%, 84.30%, 71.90% of cellulose in corn cobs was converted to ethanol, respectively.


Assuntos
Celulose/metabolismo , Etanol/metabolismo , Phanerochaete/metabolismo , Xilose/metabolismo , Zea mays/química , Zea mays/microbiologia , Biodegradação Ambiental , Celulose/química , Fracionamento Químico/métodos , Componentes Aéreos da Planta/química , Componentes Aéreos da Planta/metabolismo , Xilose/química
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