The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 ...The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 and 20°C/min) and the bonding property was evaluated by the wet shear strength and wood failure of two-ply plywood panels after soaking in water (48 hours at room temperature and followed by 1-hour boiling). The test results indicated that the NCC content had little influence on the peak temperature, activation energy and the total heat of reaction of LPF resin at 5 and 10°C/min. But at 20°C/min, LPF0.00% (LPF resin without NCC) showed the highest total heat of reaction, while LPF0.25% (LPF resin containing 0.25% NCC content) and LPF0.50% (LPF resin containing 0.50% NCC content) gave the lowest value. The wet shear strength was affected by the NCC content to a certain extent. With regard to the results of one-way analysis of variance, the bonding quality could be improved by NCC and the optimum NCC content ranged from 0.25% to 0.50%. The wood failure was also affected by the NCC content, but the trend with respect to NCC content was not clear.展开更多
The vibrational performance of wood materials critical affects the acoustic quality of a lute. The purpose of this research was to apply a multiple choice model to predict the quality of musical instruments based on d...The vibrational performance of wood materials critical affects the acoustic quality of a lute. The purpose of this research was to apply a multiple choice model to predict the quality of musical instruments based on data on lute soundboard vibrational properties of Paulownia wood. In the lute production, lute material selection mainly depends on the subjective evaluation of technicians, which is not only inefficient, but inaccurate. In this study, nine lutes were fabricated. Using the multiple selection model, the lute tone quality was predicted by the soundboard wood vibration data. Compared with the actual value, the dependent value predicted by the count of observations with the maximum probability had 22 erroneous judgments. The model precision is 87.78%. The results confirmed that the prediction model can be used as a guideline for the selection of the soundboard wood in musical instrument plants.展开更多
Nanopaper has attracted considerable interest in the fields of films and paper research.However,the challenge of integrating the many advantages of nanopaper still remains.Herein,we developed a facile strategy to fabr...Nanopaper has attracted considerable interest in the fields of films and paper research.However,the challenge of integrating the many advantages of nanopaper still remains.Herein,we developed a facile strategy to fabricate multifunctional nanocomposite paper(NGCP)composed of wood-derived nanofibrillated cellulose(NFC)and graphene as building blocks.NFC suspension was consisted of long and entangled NFCs(10–30 nm in width)and their aggregates.Before NGCP formation,NFC was chemically modified with a silane coupling agent to ensure that it could interact strongly with graphene in NGCP.The resulting NGCP samples were flexible and could be bent repeatedly without any structural damage.Within the NGCP samples,the high aspect ratio of NFC made a major contribution to its high mechanical strength,whereas the sheet-like graphene endowed the NGCP with electrical resistance and electrochemical activity.The mechanical strength of the NGCP samples decreased as their graphene content increased.However,the electrical resistance and electrochemical activity of the NGCP samples both rose with increasing content of graphene.The NGCPs still kept advantageous mechanical properties even at high temperatures around 300℃ because of the high thermal stability of NFCs and their strong entangled web-like structures.In view of its sustainable building blocks and multifunctional characteristics,the NGCP developed in this work is promising as low-cost and high-performance nanopaper.展开更多
Intrathoracic goiter(IG) is commonly located in the anterior mediastinum. Here, we report the case of a 54-year-old Chinese woman with successful removal of an intrathoracic goiter and improvement of dyspnea by a righ...Intrathoracic goiter(IG) is commonly located in the anterior mediastinum. Here, we report the case of a 54-year-old Chinese woman with successful removal of an intrathoracic goiter and improvement of dyspnea by a right posterolateral thoracotomy approach. Conclusion: Posterior mediastinal thyroid goiter with mediastinal compressive symptoms is an indication for surgery.展开更多
DNA methylation is a prevalent epigenetic modification in vertebrates,and it has been shown to be involved the regulation of gene expression and embryo development.However,it remains unclear how DNA methylation regula...DNA methylation is a prevalent epigenetic modification in vertebrates,and it has been shown to be involved the regulation of gene expression and embryo development.However,it remains unclear how DNA methylation regulates sexual development,especially in species without sex chromosomes.To determine this,we utilized zebrafish to investigate DNA methylation reprogramming during juvenile germ cell development and adult female-to-male sex transition.We reveal that primordial germ cells(PGCs)undergo significant DNA methylation reprogramming during germ cell development,and the methylome of PGCs is reset to an oocyte/ovary-like pattern at 9 days post fertilization(9 dpf).When DNA methyltransferase(DNMT)activity in juveniles was blocked after 9 dpf,the zebrafish developed into females.We also show that Tet3 is involved in PGC development.Notably,we find that DNA methylome reprogramming during adult zebrafish sex transition is similar to the reprogramming during the sex differentiation from 9 dpf PGCs to sperm.Furthermore,inhibiting DNMT activity can prevent the female-to-male sex transition,suggesting that methylation reprogramming is required for zebrafish sex transition.In summary,DNA methylation plays important roles in zebrafish germ cell development and sexual plasticity.展开更多
文摘The curing behavior of lignin-based phenol-formaldehyde (LPF) resin with different contents of nano-crystalline cellulose (NCC) was studied by differential scanning calorimetry (DSC) at different heating rates (5, 10 and 20°C/min) and the bonding property was evaluated by the wet shear strength and wood failure of two-ply plywood panels after soaking in water (48 hours at room temperature and followed by 1-hour boiling). The test results indicated that the NCC content had little influence on the peak temperature, activation energy and the total heat of reaction of LPF resin at 5 and 10°C/min. But at 20°C/min, LPF0.00% (LPF resin without NCC) showed the highest total heat of reaction, while LPF0.25% (LPF resin containing 0.25% NCC content) and LPF0.50% (LPF resin containing 0.50% NCC content) gave the lowest value. The wet shear strength was affected by the NCC content to a certain extent. With regard to the results of one-way analysis of variance, the bonding quality could be improved by NCC and the optimum NCC content ranged from 0.25% to 0.50%. The wood failure was also affected by the NCC content, but the trend with respect to NCC content was not clear.
基金financially supported by the Natural Science Foundation of China(NSFC)through Grant Number30972300
文摘The vibrational performance of wood materials critical affects the acoustic quality of a lute. The purpose of this research was to apply a multiple choice model to predict the quality of musical instruments based on data on lute soundboard vibrational properties of Paulownia wood. In the lute production, lute material selection mainly depends on the subjective evaluation of technicians, which is not only inefficient, but inaccurate. In this study, nine lutes were fabricated. Using the multiple selection model, the lute tone quality was predicted by the soundboard wood vibration data. Compared with the actual value, the dependent value predicted by the count of observations with the maximum probability had 22 erroneous judgments. The model precision is 87.78%. The results confirmed that the prediction model can be used as a guideline for the selection of the soundboard wood in musical instrument plants.
基金This research was funded by the National Natural Science Foundation of China(Grant No.31800487)the Natural Science Foundation of Heilongjiang Province of China(Grant No.QC2018018)+2 种基金the Fundamental Research Funds for the Central Universities(Grant No.2572019BB03)the Foundation of Key Laboratory of Pulp and Paper Science and Technology of Ministry of Education/Shandong Province of China(Grant No.KF201721)Any research results expressed in this paper are those of the writer(s)and do not necessarily reflect the views of the foundations.
文摘Nanopaper has attracted considerable interest in the fields of films and paper research.However,the challenge of integrating the many advantages of nanopaper still remains.Herein,we developed a facile strategy to fabricate multifunctional nanocomposite paper(NGCP)composed of wood-derived nanofibrillated cellulose(NFC)and graphene as building blocks.NFC suspension was consisted of long and entangled NFCs(10–30 nm in width)and their aggregates.Before NGCP formation,NFC was chemically modified with a silane coupling agent to ensure that it could interact strongly with graphene in NGCP.The resulting NGCP samples were flexible and could be bent repeatedly without any structural damage.Within the NGCP samples,the high aspect ratio of NFC made a major contribution to its high mechanical strength,whereas the sheet-like graphene endowed the NGCP with electrical resistance and electrochemical activity.The mechanical strength of the NGCP samples decreased as their graphene content increased.However,the electrical resistance and electrochemical activity of the NGCP samples both rose with increasing content of graphene.The NGCPs still kept advantageous mechanical properties even at high temperatures around 300℃ because of the high thermal stability of NFCs and their strong entangled web-like structures.In view of its sustainable building blocks and multifunctional characteristics,the NGCP developed in this work is promising as low-cost and high-performance nanopaper.
文摘Intrathoracic goiter(IG) is commonly located in the anterior mediastinum. Here, we report the case of a 54-year-old Chinese woman with successful removal of an intrathoracic goiter and improvement of dyspnea by a right posterolateral thoracotomy approach. Conclusion: Posterior mediastinal thyroid goiter with mediastinal compressive symptoms is an indication for surgery.
基金supported by the grants from the Ministry of Science and Technology of China(Grant No.2018YFC1003300)the National Natural Science Foundation of China(Grant Nos.31630040,81871171,31871454 and 31671540)+2 种基金the CAS Funding(Grant No.QYZDY-SSWSMC016)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB38020500)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.292020000011)
文摘DNA methylation is a prevalent epigenetic modification in vertebrates,and it has been shown to be involved the regulation of gene expression and embryo development.However,it remains unclear how DNA methylation regulates sexual development,especially in species without sex chromosomes.To determine this,we utilized zebrafish to investigate DNA methylation reprogramming during juvenile germ cell development and adult female-to-male sex transition.We reveal that primordial germ cells(PGCs)undergo significant DNA methylation reprogramming during germ cell development,and the methylome of PGCs is reset to an oocyte/ovary-like pattern at 9 days post fertilization(9 dpf).When DNA methyltransferase(DNMT)activity in juveniles was blocked after 9 dpf,the zebrafish developed into females.We also show that Tet3 is involved in PGC development.Notably,we find that DNA methylome reprogramming during adult zebrafish sex transition is similar to the reprogramming during the sex differentiation from 9 dpf PGCs to sperm.Furthermore,inhibiting DNMT activity can prevent the female-to-male sex transition,suggesting that methylation reprogramming is required for zebrafish sex transition.In summary,DNA methylation plays important roles in zebrafish germ cell development and sexual plasticity.
