Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellu...Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellulose, hemicellulose and lignin from switch grass to obtain much more useful chemicals and enhance the residue solid to be hydrolyzed by enzymes. The six different pretreatment methods were studied, such as hot water pretreatment （HWP） alone, dilute acid pretreatment （DAP）, ammonia pretreatment （AP）, lime pretreatment （LP）, organosolv water / ehanol pretreatment （OWEP）, and organosolv water / acetone pretreatment （OWAP）. It was the best method combining DAP with OWEP because the hemicellulose sugars were recovered in the first residual liquid while a varied amount of cellulose was retained in the residual solid and the lignin fraction was obtained by simply adjusting the pH from the second liquid. The result shows the optimal two-stage process consisted of the first stage DAP at 428 K for 7 min with 0.8% sulfuric acid, resulting in 79.82% glucose recovery yield and 98.74% xylose removal and the second stage OWEP at 468K for 20 min in 45% （v / v） ethanol with 0.4% NaOH, resulting in 62% total glucose yield 99% xylose and 80% lignin removal. After enzymatic hydrolysis, the glucose yield was up to 92.6%, compared with 16% yield from untreated switch grass. Scanning electron microscopy （SEM） highlighted the differences in switch grass structure from the various pretreatment methods during biomass fractionation.展开更多
In this study, a system involving two-dimensional, column-switching high-performance liquid chromatography （HPLC） coupled with tandem mass spectrometry （LC-MS/MS） was developed and optimized for the analysis of an...In this study, a system involving two-dimensional, column-switching high-performance liquid chromatography （HPLC） coupled with tandem mass spectrometry （LC-MS/MS） was developed and optimized for the analysis of antibiotics and their related substances. In the first-dimensional chromatography, the analytes were separated on a zwitterion exchange-reversed phase-hydrophitic interaction （ZIC-RP-HILIC） mixed-mode column coupled with tandem mass spectrometry （LC-MS/MS）. A commonly used reversed phase LC column was employed in the second-dimensional chromatography. The mobile phase for the ZIC-RP-HILIC mixed-mode chromatography consisted of a volatile buffer that was compatible with LC-MS/MS, which enhanced the efficiency of ionization for structure elucidation. The antibiotic impurities eluted in the ion-pairing reversed phase chromatography were directly characterized by the ZIC-RP-HILIC-MS system, and the orthogonal separation of ZIC-RP-HILIC mixed-mode chromatography and reversed phase LC provided extra confidence that no impurity was missed. The efficiency of this method was demonstrated in the analysis of penicillin V potassium, oxacillin sodium, ceftriaxone sodium, and their impurities. In addition, this method is convenient for impurity profiling of antibiotics, and may be used for the analysis of other pharmaceutical ingredients.展开更多
A single-/dual-wavelength switchable and tunable erbium-doped fiber laser(EDFL) with super-narrow linewidth has been proposed and experimentally demonstrated at room temperature. The fiber laser is based on a compound...A single-/dual-wavelength switchable and tunable erbium-doped fiber laser(EDFL) with super-narrow linewidth has been proposed and experimentally demonstrated at room temperature. The fiber laser is based on a compound cavity simply composed of a ring main cavity and a two-ring subring cavity(TR-SC). Regardless of single- or dual-wavelength operation, the EDFL could always work well in single-longitudinal-mode(SLM) state at every oscillating wavelength. In dual-wavelength operation, the spacing could be tuned from 0 nm to 4.83 nm. In single-wavelength operation, the EDFL could lase at a fixed wavelength of 1 543.65 nm or another wavelength with a tunable range of 4.83 nm. The super-narrow linewidths of 550 Hz and 600 Hz for two wavelengths are obtained. The proposed EDFL has potential applications in microwave/terahertz-wave generation and high-precision distributed fiber optical sensing.展开更多
基金Acknowledgments This research was supported by Hubei Provincal Department of Education （No. CXY2009B2008）, Angel Yeast Co.Ltd （SDH200800230）, the Science Foundation of Yichang City （No. A2007103-1）, the Alan G. MacDiarmid Institute of Renewable Energy, Yichang, China and the USDA Western Regional Research Center （WRRC）. The authors thank WRRC Center Director James N. Seiber, Artur, Klamczynski and Charles Lee for the thoughtful discussions and technical insights, and Miss Tina William for the SEM imagines.
文摘Switch grass was developed as a pioneer energy crop in USA with great industrial prospect. It contains about 60% sugars and 18% lignin. The purpose of this research is to find pretreatment process to fractionate cellulose, hemicellulose and lignin from switch grass to obtain much more useful chemicals and enhance the residue solid to be hydrolyzed by enzymes. The six different pretreatment methods were studied, such as hot water pretreatment （HWP） alone, dilute acid pretreatment （DAP）, ammonia pretreatment （AP）, lime pretreatment （LP）, organosolv water / ehanol pretreatment （OWEP）, and organosolv water / acetone pretreatment （OWAP）. It was the best method combining DAP with OWEP because the hemicellulose sugars were recovered in the first residual liquid while a varied amount of cellulose was retained in the residual solid and the lignin fraction was obtained by simply adjusting the pH from the second liquid. The result shows the optimal two-stage process consisted of the first stage DAP at 428 K for 7 min with 0.8% sulfuric acid, resulting in 79.82% glucose recovery yield and 98.74% xylose removal and the second stage OWEP at 468K for 20 min in 45% （v / v） ethanol with 0.4% NaOH, resulting in 62% total glucose yield 99% xylose and 80% lignin removal. After enzymatic hydrolysis, the glucose yield was up to 92.6%, compared with 16% yield from untreated switch grass. Scanning electron microscopy （SEM） highlighted the differences in switch grass structure from the various pretreatment methods during biomass fractionation.
基金The Key Projects in the National Science&Technology Pillar Program during the Twelfth Five-year Plan Period(Grant No.2012BAK25B02)
文摘In this study, a system involving two-dimensional, column-switching high-performance liquid chromatography （HPLC） coupled with tandem mass spectrometry （LC-MS/MS） was developed and optimized for the analysis of antibiotics and their related substances. In the first-dimensional chromatography, the analytes were separated on a zwitterion exchange-reversed phase-hydrophitic interaction （ZIC-RP-HILIC） mixed-mode column coupled with tandem mass spectrometry （LC-MS/MS）. A commonly used reversed phase LC column was employed in the second-dimensional chromatography. The mobile phase for the ZIC-RP-HILIC mixed-mode chromatography consisted of a volatile buffer that was compatible with LC-MS/MS, which enhanced the efficiency of ionization for structure elucidation. The antibiotic impurities eluted in the ion-pairing reversed phase chromatography were directly characterized by the ZIC-RP-HILIC-MS system, and the orthogonal separation of ZIC-RP-HILIC mixed-mode chromatography and reversed phase LC provided extra confidence that no impurity was missed. The efficiency of this method was demonstrated in the analysis of penicillin V potassium, oxacillin sodium, ceftriaxone sodium, and their impurities. In addition, this method is convenient for impurity profiling of antibiotics, and may be used for the analysis of other pharmaceutical ingredients.
基金supported by the Youth Foundation of Hebei Educational Committee(No.QN2015235)the Technology Foundation for Selected Overseas Chinese Scholar of Ministry of Human Resources and Social Security of China(No.CG2015003006)the Special Funding of Comprehensive Capability Enhancement Program from Hebei University
文摘A single-/dual-wavelength switchable and tunable erbium-doped fiber laser(EDFL) with super-narrow linewidth has been proposed and experimentally demonstrated at room temperature. The fiber laser is based on a compound cavity simply composed of a ring main cavity and a two-ring subring cavity(TR-SC). Regardless of single- or dual-wavelength operation, the EDFL could always work well in single-longitudinal-mode(SLM) state at every oscillating wavelength. In dual-wavelength operation, the spacing could be tuned from 0 nm to 4.83 nm. In single-wavelength operation, the EDFL could lase at a fixed wavelength of 1 543.65 nm or another wavelength with a tunable range of 4.83 nm. The super-narrow linewidths of 550 Hz and 600 Hz for two wavelengths are obtained. The proposed EDFL has potential applications in microwave/terahertz-wave generation and high-precision distributed fiber optical sensing.
