Demethylation of Alkali Lignin with Halogen Acids and Its Application to Phenolic Resins

Lignin, a byproduct from the chemical processing of lignocellulosic biomass, is a polyphenolic compound that has potential as a partial phenol substitute in phenolic adhesive formulations. In this study, HBr and HI were used as reagents to demethylate an alkali lignin (AL) to increase its hydroxyl content and thereby enhance its reactivity for the preparation of phenolic resins. Analyses by FT-IR, 1H-NMR and 2D-NMR(HSQC) demonstrated both a decrease in methoxyl groups and an increase in hydroxyl groups for each demethylated lignin (DL). In addition, the molar amounts of phenolic hydroxyls, determined by 1H-NMR, increased to 0.67 mmol/g for the HI-DL, and 0.64 mmol/g for the HBr-DL, from 0.52 mmol/g for the AL. These results showed that HI, a stronger nucleophilic reagent than HBr, provided a higher degree of AL demethylation. Lignin-containing resins, prepared by copolymerization, met the bonding strength standard for exterior plywood with DL used to replace as much as 50 wt.% of phenol. The increased hydroxyl contents resulting from the lignin demethylations also imparted faster cure times for the lignin-containing resins and lower formaldehyde emissions. Altogether, the stronger nucleophilicity of HI, compared to HBr, impacted the degree of lignin demethylation, and carried through to measurable differences the thermal properties and performance of the lignin-containing PF resins

Cortex-restricted deletion of Foxp1 impairs barrel formation and induces aberrant tactile responses in a mouse model of autism

Abstract Background Many children and young people with autism spectrum disorder (ASD) display touch defensiveness or avoidance (hypersensitivity), or engage in sensory seeking by touching people or objects (hyposensitivity). Abnormal sensory responses have also been noticed in mice lacking ASD-associated genes. Tactile sensory information is normally processed by the somatosensory system that travels along the thalamus to the primary somatosensory cortex. The neurobiology behind tactile sensory abnormalities, however, is not fully understood. Methods We employed cortex-specific Foxp1 knockout (Foxp1-cKO) mice as a model of autism in this study. Tactile sensory deficits were measured by the adhesive removal test. The mice’s behavior and neural activity were further evaluated by the whisker nuisance test and c-Fos immunofluorescence, respectively. We also studied the dendritic spines and barrel formation in the primary somatosensory cortex by Golgi staining and immunofluorescence. Results Foxp1-cKO mice had a deferred response to the tactile environment. However, the mice exhibited avoidance behavior and hyper-reaction following repeated whisker stimulation, similar to a fight-or-flight response. In contrast to the wild-type, c-Fos was activated in the basolateral amygdala but not in layer IV of the primary somatosensory cortex of the cKO mice. Moreover, Foxp1 deficiency in cortical neurons altered the dendrite development, reduced the number of dendritic spines, and disrupted barrel formation in the somatosensory cortex, suggesting impaired somatosensory processing may underlie the aberrant tactile responses. Limitations It is still unclear how the defective thalamocortical connection gives rise to the hyper-reactive response. Future experiments with electrophysiological recording are needed to analyze the role of thalamo-cortical-amygdala circuits in the disinhibiting amygdala and enhanced fearful responses in the mouse model of autism. Conclusions Foxp1-cKO mice have tactile sensory deficits while exhibit hyper-reactivity, which may represent fearful and emotional responses controlled by the amygdala. This study presents anatomical evidence for reduced thalamocortical connectivity in a genetic mouse model of ASD and demonstrates that the cerebral cortex can be the origin of atypical sensory behaviors

The Role of Protected Areas in Mitigating Vegetation Disturbances on the Qinghai-Tibetan Plateau

Long-term vegetation dynamics with satellite observations can provide valuable insights into natural variation in ecosystems and quantify disturbances associated with external pressures. Monitoring vegetation dynamics within protected areas (PAs) is essential, given their crucial role in protecting biodiversity and maintaining ecosystem integrity. In this study, using the normalized difference vegetation index (NDVI) and Breaks For Additive Seasonal and Trend (BFAST)model, we detected vegetation dynamics especially abrupt changes inside nature reserves (NRs, the primary type of PAs) on the Qinghai-Tibetan Plateau from 2000 to 2020. We then applied the matching approach and postmatching regression to evaluate the effect of NRs on natural vegetation with average NDVI, NDVI slope, and the number of abrupt changes. Our results showed that 78.97% of the vegetation within NRs exhibited greening trends. In addition, 29.15% of the area inside of the NRs experienced 1 or more abrupt changes, with the major change type interrupted greening (15.96%), followed by greening to browning (6.27%) and browning to greening (4.00%). The NRs significantly reduced the frequency of disturbances, and older NRs also showed a higher value of average NDVI compared to those in matched unprotected areas. Postregression models indicated that vegetation in newer NRs tended to be more vulnerable to disturbances and stricter NR management could benefit vegetation enhancement. Our analysis offers a new approach to vegetation dynamic monitoring that considers short-term disturbances. The findings of this work can help better understand effectiveness of PAs on ecosystem protection and offer practical guidance to future PAs management

Exploration and Application of Microsurgical Training in Young Neurosurgeons at Peking Union Medical College Hospital

Microsurgical technique is essential for neurosurgeons, which demands good hand-eye coordination and fine motor skills. It is therefore necessary to provide systematic microsurgical training for young doctors with limited clinical experience. However, there is currently a lack of unified training programs in China. Based on clinical needs, the Neurosurgery Department of Peking Union Medical College Hospital has developed an integrated, immersive, and high-intensity microsurgical training course that covers training closely related to clinical practice, such as the use of microsurgical instruments, suture of gauze holes, anastomosis of artificial blood vessels, anastomosis of middle cerebral artery, and the use of micro drills. Since March 2022, six training sessions have been completed with a total of 12 trainees, and all have passed the assessment. Four of them have been recognized as microsurgical main surgeons. Preliminary data shows that this training course has helped to improve the microsurgical skills of young neurosurgeons, providing a reference for future microsurgical training programs