The crystal structure of the metal-organic frame Ca（C5H9O5）2·CH3OH·2H2O（1） has been synthesized and characterized.Complex 1 belongs to a tetragonal P43212 space group.In complex 1,the sugar moiety shows ...The crystal structure of the metal-organic frame Ca（C5H9O5）2·CH3OH·2H2O（1） has been synthesized and characterized.Complex 1 belongs to a tetragonal P43212 space group.In complex 1,the sugar moiety shows a beta-L configuration of pyranose form.The calcium（Ⅱ） is eight-coordinated,binding to four such sugar moieties,via O（1）,O（2） of two molecules and O（3）,O（4） of the other two,with the 4-hydroxy group being deprotonated.The water and methanol molecules are not coordinated to the calcium ion.展开更多
One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates t...One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates the 4-connected zeotype topology by the employment of L-alanine. To the best of knowledge, it’s the first report that metal-organic framework based on amino acid features the chiral zeolitic rho-type structure. Compound 1 was characterized by X-ray powder diffraction, elemental analysis and single-crystal X-ray diffraction. Crystal data: C6 H9 CdN2 O4, Mr = 285.55, cubic system, space group I432, a = 24.0795（6）, V = 13961.9（10） ?3, Z = 48, Dc = 1.630 Mg/m3, F（000） = 6672, μ（Mo Kα） = 1.865 mm-1, S = 1.058, R = 0.0271 and wR = 0.0312 for 1870 observed reflections with I > 2σ（I）. The circular dichroism（CD） property of compound 1 was also investigated.展开更多
采用L-精氨酸对传统均苯三甲酸(BTC)溶剂热法合成的Cu基金属有机骨架化合物(Cu-BTC)进行改性,得到新型化合物(Cu-BTC-Arg),并通过固定床动态吸附实验考察了Cu-BTC-Arg和Cu-BTC吸附CO_2的性能。表征结果显示:L-精氨酸只是辅助化溶剂,并...采用L-精氨酸对传统均苯三甲酸(BTC)溶剂热法合成的Cu基金属有机骨架化合物(Cu-BTC)进行改性,得到新型化合物(Cu-BTC-Arg),并通过固定床动态吸附实验考察了Cu-BTC-Arg和Cu-BTC吸附CO_2的性能。表征结果显示:L-精氨酸只是辅助化溶剂,并未配位至Cu^(2+)上;Cu-BTC-Arg比Cu-BTC具有更小的晶粒尺寸、更大的比表面积和微孔体积。实验结果表明,两种不同L-精氨酸加入量合成的Cu-BTC-Arg均在室温、烟气中无水蒸气、烟气流量80 m L/min的条件下CO_2吸附量最大,吸附接近饱和时的CO_2吸附量均为4.9 mmol/g,远高于Cu-BTC的CO_2吸附量。Cu-BTC-Arg对CO_2的吸附以物理吸附为主。展开更多
In the low-level RF control field,ADC acquisition accuracy and noise set the boundary of our control ability,making it important to develop low-noise acquisition systems.From the design to test stage,all the noise ter...In the low-level RF control field,ADC acquisition accuracy and noise set the boundary of our control ability,making it important to develop low-noise acquisition systems.From the design to test stage,all the noise terms should be understood and characterized.The specific need addressed here is the precision acquisition system for the second Linac Coherent Light Source(LCLS-Ⅱ),led by SLAC National Accelerator Laboratory.Test circuit boards for the LTC2174 and AD9268 ADCs are designed and fabricated by LBNL.An ADC test framework based on FPGA evaluation board to assess performance has been developed.The ADC test framework includes both DSP(Digital Signal Processing) firmware and processing software.It is useful for low-level RF control and other synchronization projects.Investigating the clock jitter between two channels give us an understanding of that noise source.Working with the test framework,the raw ADC data are transferred to a computer through a Gigabit Ethernet interface.Then short-term error signal can be calculated based on a sine wave fit.By changing low-pass filter bandwidth,relative long-term performance can also be obtained.Amplitude jitter and differential phase jitter are the key issues for ADCs.This paper will report the test results for LTC2174 and AD9268 chips.The integral amplitude jitter is smaller than 0.003%,and the integral phase noise is smaller than 0.0015°(measured at 47 MHz RF,100 MHz clock,bandwidth 1 Hz to 100 kHz) for both ADC chips.展开更多
Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs ar...Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs are commonly limited due to the weak hydrostability of their metal–ligand coordination bonds,particularly under humid and aqueous conditions.In this work,as an example,the hydrolysis behaviours of ZIF-L with a special focus on ZIF-L coatings were tested at aqueous conditions with a wide range of pHs to systematically study and fundamentally understand their structural stability and degradation mechanism.Pristine ZIF-L powder and ZIF-L coatings were severely damaged after only 24 h in aqueous media.Interestingly,the ZIF-L coatings showed two distinct hydrolyzation pathways regardless of pH conditions,exhibiting either a ring-shaped etching or unfolding behaviours.While the ZIF-L powders were hydrolyzed almost identically across all pH conditions.With this new understanding,a facile silk fibroin(SF)protein modification method was developed to enhance the hydrostability of ZIF-L coatings in aqueous media.The effect of protein concentration on surface coating was systemically studied.ZIF-L coating retained its surface morphology after soaking in water and demonstrated switchable super wetting properties and superior separation performance for oil/water mixture.As a result,the quick SF protein modification significantly enhanced the stability of ZIF-L coatings under various pHs,while retaining their switchable wetting property and excellent separation performance.展开更多
The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for p...The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for point-of-care testing(POCT) of cholesterol. In this work, a cascade catalytic system of cholesterol is developed by encapsulation of cholesterol oxidase(Ch Ox) and Pd Cu Au nanoparticles into zeolitic imidazolate framework-L(Ch Ox/PCA@ZIF-L). Results indicate that ZIF-L carrier can significantly increase the catalytic activity of single or multiple enzymes, due to its high loading capacity and efficient molecular transport. Under the optimal conditions, the absorbance of reaction system performs linear relationships with the concentration of cholesterol in two intervals from 0.0005 mmol/L to 1.0000 mmol/L, with a limit of detection of 0.2176 μmol/L. The proposed colorimetric strategy based on Ch Ox/PCA@ZIF-L performs a good agreement with the results provided by chemiluminescence method for the serum cholesterol detection. Interestingly, a simple paper-based sensing system is constructed through a pre-reaction-transfer operation, which gets rid of the complex pre-processing requirements of traditional operations on filter paper. The presented strategy allows for the sensitive, convenient, costless assay of serum cholesterol,and paves a new way to design the POCT device for daily monitoring of healthy.展开更多
基金supported by the Ministry of Science and Technology through the Agriculture Science and Technology Achievements Transformation Fund(No.2013GB23600669)the Science and Technology Planning Project of Guangzhou Municipality,China(No.2011Y2-00012)
文摘The crystal structure of the metal-organic frame Ca（C5H9O5）2·CH3OH·2H2O（1） has been synthesized and characterized.Complex 1 belongs to a tetragonal P43212 space group.In complex 1,the sugar moiety shows a beta-L configuration of pyranose form.The calcium（Ⅱ） is eight-coordinated,binding to four such sugar moieties,via O（1）,O（2） of two molecules and O（3）,O（4） of the other two,with the 4-hydroxy group being deprotonated.The water and methanol molecules are not coordinated to the calcium ion.
基金supported financially by National Natural Science Foundation of China(No.21601080)
文摘One new chiral zeolitic rho-type metal-organic framework [Cd（L-ala）2]n（1） has been successfully synthesized based on L-alanine chiral ligand, which demonstrates the feasibility of fabricating MOF that integrates the 4-connected zeotype topology by the employment of L-alanine. To the best of knowledge, it’s the first report that metal-organic framework based on amino acid features the chiral zeolitic rho-type structure. Compound 1 was characterized by X-ray powder diffraction, elemental analysis and single-crystal X-ray diffraction. Crystal data: C6 H9 CdN2 O4, Mr = 285.55, cubic system, space group I432, a = 24.0795（6）, V = 13961.9（10） ?3, Z = 48, Dc = 1.630 Mg/m3, F（000） = 6672, μ（Mo Kα） = 1.865 mm-1, S = 1.058, R = 0.0271 and wR = 0.0312 for 1870 observed reflections with I > 2σ（I）. The circular dichroism（CD） property of compound 1 was also investigated.
文摘采用L-精氨酸对传统均苯三甲酸(BTC)溶剂热法合成的Cu基金属有机骨架化合物(Cu-BTC)进行改性,得到新型化合物(Cu-BTC-Arg),并通过固定床动态吸附实验考察了Cu-BTC-Arg和Cu-BTC吸附CO_2的性能。表征结果显示:L-精氨酸只是辅助化溶剂,并未配位至Cu^(2+)上;Cu-BTC-Arg比Cu-BTC具有更小的晶粒尺寸、更大的比表面积和微孔体积。实验结果表明,两种不同L-精氨酸加入量合成的Cu-BTC-Arg均在室温、烟气中无水蒸气、烟气流量80 m L/min的条件下CO_2吸附量最大,吸附接近饱和时的CO_2吸附量均为4.9 mmol/g,远高于Cu-BTC的CO_2吸附量。Cu-BTC-Arg对CO_2的吸附以物理吸附为主。
基金supported by the US.Department of Energy(DEAC02-05CH11231)the China Scholarship Council
文摘In the low-level RF control field,ADC acquisition accuracy and noise set the boundary of our control ability,making it important to develop low-noise acquisition systems.From the design to test stage,all the noise terms should be understood and characterized.The specific need addressed here is the precision acquisition system for the second Linac Coherent Light Source(LCLS-Ⅱ),led by SLAC National Accelerator Laboratory.Test circuit boards for the LTC2174 and AD9268 ADCs are designed and fabricated by LBNL.An ADC test framework based on FPGA evaluation board to assess performance has been developed.The ADC test framework includes both DSP(Digital Signal Processing) firmware and processing software.It is useful for low-level RF control and other synchronization projects.Investigating the clock jitter between two channels give us an understanding of that noise source.Working with the test framework,the raw ADC data are transferred to a computer through a Gigabit Ethernet interface.Then short-term error signal can be calculated based on a sine wave fit.By changing low-pass filter bandwidth,relative long-term performance can also be obtained.Amplitude jitter and differential phase jitter are the key issues for ADCs.This paper will report the test results for LTC2174 and AD9268 chips.The integral amplitude jitter is smaller than 0.003%,and the integral phase noise is smaller than 0.0015°(measured at 47 MHz RF,100 MHz clock,bandwidth 1 Hz to 100 kHz) for both ADC chips.
基金supported by start-up funding from the School of Engineering,at the University of Edinburgh.
文摘Zeolitic imidazolate frameworks(ZIFs)are an important subclass of metal-organic frameworks(MOFs)with zeolite-type topology,which can be fabricated under ambient synthesis conditions.However,the applications of ZIFs are commonly limited due to the weak hydrostability of their metal–ligand coordination bonds,particularly under humid and aqueous conditions.In this work,as an example,the hydrolysis behaviours of ZIF-L with a special focus on ZIF-L coatings were tested at aqueous conditions with a wide range of pHs to systematically study and fundamentally understand their structural stability and degradation mechanism.Pristine ZIF-L powder and ZIF-L coatings were severely damaged after only 24 h in aqueous media.Interestingly,the ZIF-L coatings showed two distinct hydrolyzation pathways regardless of pH conditions,exhibiting either a ring-shaped etching or unfolding behaviours.While the ZIF-L powders were hydrolyzed almost identically across all pH conditions.With this new understanding,a facile silk fibroin(SF)protein modification method was developed to enhance the hydrostability of ZIF-L coatings in aqueous media.The effect of protein concentration on surface coating was systemically studied.ZIF-L coating retained its surface morphology after soaking in water and demonstrated switchable super wetting properties and superior separation performance for oil/water mixture.As a result,the quick SF protein modification significantly enhanced the stability of ZIF-L coatings under various pHs,while retaining their switchable wetting property and excellent separation performance.
基金supported by the National Natural Science Foundation of China (Nos. 81971765, 31771099, 31671025 and 81871504)the Natural Science Foundation of Guangdong Province (No. 2020A1515011066)。
文摘The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for point-of-care testing(POCT) of cholesterol. In this work, a cascade catalytic system of cholesterol is developed by encapsulation of cholesterol oxidase(Ch Ox) and Pd Cu Au nanoparticles into zeolitic imidazolate framework-L(Ch Ox/PCA@ZIF-L). Results indicate that ZIF-L carrier can significantly increase the catalytic activity of single or multiple enzymes, due to its high loading capacity and efficient molecular transport. Under the optimal conditions, the absorbance of reaction system performs linear relationships with the concentration of cholesterol in two intervals from 0.0005 mmol/L to 1.0000 mmol/L, with a limit of detection of 0.2176 μmol/L. The proposed colorimetric strategy based on Ch Ox/PCA@ZIF-L performs a good agreement with the results provided by chemiluminescence method for the serum cholesterol detection. Interestingly, a simple paper-based sensing system is constructed through a pre-reaction-transfer operation, which gets rid of the complex pre-processing requirements of traditional operations on filter paper. The presented strategy allows for the sensitive, convenient, costless assay of serum cholesterol,and paves a new way to design the POCT device for daily monitoring of healthy.
