Bio-based Polyurethane Foams Made from Microwave Liquefaction of Biomass

Polyurethane (PU) foam is one of the most versatile construction insulations due to its low density, low thermal conductivity, and high mechanical performance. However, it is still highly dependent on petro-based chemicals, i.e. polyol and isocyanate. In this work, biomass, such as rape straw, switchgrass, and yaupon holly (Ilex vomitoria) were liquefied using microwave energy to produce bio-based polyol in order to substitute petro-based polyol in the production of PU foam. Cellulose nanocrystals (CNCs) were also extracted from liquefaction solid residue. They were then applied to reinforce high bio-content PU foam. Moreover, lignin was fractionated from bio-polyol by adding distilled water, and then it was used as filler to reinforce PU foam. In addition, the microwave liquefaction conditions of woody underbrush were optimized to obtain the maximum conversion yield. The overall results indicated that higher liquefaction temperature was beneficial to obtaining higher energy consumption efficiency as heated by microwave irradiation. Moderate liquefaction conditions could result in a high content of hydroxyl group products, while severe reaction conditions could produce a high yield of levulinic ester products. The rapid decomposition of hemicellulose and lignin during liquefaction process contributed to the decrease of activation energy (Eα), whereas the recondensation/repolymerization reaction could remarkably increase Eα. Most of lignin and hemicelluloses in the solid residues from 180oC/7.5 min were removed by liquefaction. The retained hemicelluloses and impurities were then eliminated by 2% NaOH and 5% H2O2 treatments. With high-intensity ultrasonic nanofibrillation treatment, CNCs with an average diameter of 12.59 nm were obtained from chemical purified samples. PU foam with 40% bio-polyol could be remarkably reinforced by 4% CNCs because the hydroxyl-rich structure in CNCs increased the crosslinking density. As compared with PU foam without CNCs, the Young’s modulus and compressive stress in the 4% CNCs reinforced bio-foam increased by 590% and 150%, respectively. The foam with 10% lignin fractionated from bio-polyol had the highest apparent density of 0.061g/cm3, best mechanical strength, and superior thermal stability. The optimized parameters of the microwave liquefaction of underbrush can be summarized as follows: 1) particle size was controlled in the range of 16- to 40-mesh; 2) both the glycerol to EG ratio and liquid to solid ratio were set at 3:1; and 3) the liquefaction process was conducted at 160 °C for 10 min and catalyzed by 1.5% H2SO4. The optimal liquefaction conversion yield was 94.9%

FedAL: Black-Box Federated Knowledge Distillation Enabled by Adversarial Learning

Knowledge distillation (KD) can enable collaborative learning among distributed clients that have different model architectures and do not share their local data and model parameters with others. Each client updates its local model using the average model output/feature of all client models as the target, known as federated KD. However, existing federated KD methods often do not perform well when clients' local models are trained with heterogeneous local datasets. In this paper, we propose Federated knowledge distillation enabled by Adversarial Learning (FedAL) to address the data heterogeneity among clients. First, to alleviate the local model output divergence across clients caused by data heterogeneity, the server acts as a discriminator to guide clients' local model training to achieve consensus model outputs among clients through a min-max game between clients and the discriminator. Moreover, catastrophic forgetting may happen during the clients' local training and global knowledge transfer due to clients' heterogeneous local data. Towards this challenge, we design the less-forgetting regularization for both local training and global knowledge transfer to guarantee clients' ability to transfer/learn knowledge to/from others. Experimental results show that FedAL and its variants achieve higher accuracy than other federated KD baselines

Catholic disaster relief in China (1840-1949). Based on the case of Hunan

Participating and holding public charity is a long tradition of the Catholic and a concrete embodiment of the Catholic active participation in social care. During the period from 1840 to 1949, the political structure, social class, and economic order of Chinese society underwent earth-shaking changes, and wars and turmoil were frequent. In this period of social turmoil, while preaching in China, Catholicism also adheres to religious concepts, actively practices the concept of charity, and participates in social charity services in many ways. Missionaries, who had come to China in modern times, had actively participated in various charitable undertakings in China with full religious enthusiasm, especially disaster and famine relief. At present, less attention has been paid to the research on disaster relief undertakings carried out by Catholic missionaries in China, especially the history of local religious disaster relief needs to be improved. The Catholic's disaster relief in China has always played an indelible role in disaster relief. And reflecting on and drawing on the historical experience is of great practical significance for the current disaster resistance and relief. Studying the disaster relief undertakings carried out by the Catholic Church in modern Hunan could further expand the research on disaster and relief in China and could contribute to similar research in other countries

Characterization of Biobased Polyurethane Foams Employing Lignin Fractionated from Microwave Liquefied Switchgrass

Lignin samples fractionated from microwave liquefied switchgrass were applied in the preparation of semirigid polyurethane (PU) foams without purification. The objective of this study was to elucidate the influence of lignin in the PU matrix on the morphological, chemical, mechanical, and thermal properties of the PU foams. The scanning electron microscopy (SEM) images revealed that lignin with 5 and 10% content in the PU foams did not influence the cell shape and size. The foam cell size became larger by increasing the lignin content to 15%. Fourier transform infrared spectroscopy (FTIR) indicated that chemical interactions occurred between the lignin hydroxyl and isocyanate revealing that lignin was well dispersed in the matrix materials. The apparent density of the foam with 10% lignin increased by 14.2% compared to the control, while the foam with 15% lignin had a decreased apparent density. The effect of lignin content on the mechanical properties was similar to that on apparent density. The lignin containing foams were much more thermally stable than the control foam as evidenced by having higher initial decomposition temperature and maximum decomposition rate temperature from the thermogravimetric analysis (TGA) profiles

Effect of Chitosan Coating with Different Molecular Weights on the Storage Quality of Postharvest Passion Fruit (Passiflora edulis Sims)

To study the preservation effect of chitosan coating with different molecular weights on postharvest passion fruit, the "Qinmi No.9" was coated with chitosan of molecular weights of 30, 50, 100, 150 and 200 kDa (1.5%, w/v) to determine the quality of passion fruit during storage. The results showed that chitosan coating with different molecular weights was able to delay the shrinkage and yellowing, reduce the weight loss rate and inhibit the decay of passion fruit. Moreover, chitosan with a larger molecular weight was more conducive to delaying the ripening and senescence of passion fruit, as well as reducing shrinkage, and decay. At the end of storage, the weight loss of fruits coated with 200 kDa chitosan was nearly 10% less than that coated with 30 kDa chitosan, and the fruits coated with 150 and 200 kDa chitosan did not decay. The lower molecular weight (30 and 50 kDa) and higher molecular weight (150 kDa) chitosan were more effective in inhibiting weight loss, total soluble solids and soluble sugar metabolism, and maintaining titratable acid, flavonoid and total phenol contents of fruit during storage. The chitosan with 150 kDa had the best effect in maintaining the vitamin C content, which was 1.12 times higher than the control group at the end of storage. In conclusion, chitosan with different molecular weights was effective to delay senescence, slow down water loss and shrink of passion fruit and maintain the quality, chitosan with 150 kDa was more suitable to maintain the quality of postharvest passion fruit

Highly-stable, flexible delivery of microjoule-level ultrafast pulses in vacuumized anti-resonant hollow-core fibers for active synchronization

We demonstrate the stable and flexible light delivery of multi-{\mu}J, sub-200-fs pulses over a ~10-m-long vacuumized anti-resonant hollow-core fiber (AR-HCF), which was successfully used for high-performance pulse synchronization. Compared with the pulse train launched into the AR-HCF, the transmitted pulse train out of the fiber exhibits excellent stabilities in pulse power and spectrum, with pointing stability largely improved. The walk-off between the fiber-delivery and the other free-space-propagation pulse trains, in an open loop, was measured to be <6 fs root-mean-square (RMS) over 90 minutes, corresponding to a relative optical-path variation of <2x10-7. This walk-off can be further suppressed to ~2 fs RMS simply using an active control loop, highlighting the great application potentials of this AR-HCF set-up in large-scale laser and accelerator facilities

Generation of induced pluripotent stem cell lines from 3 distinct laminopathies bearing heterogeneous mutations in lamin A/C

The term laminopathies defines a group of genetic disorders caused by defects in the nuclear envelope, mostly the lamins. Lamins are the main constituents of the nuclear lamina, a filamentous meshwork associated with the inner nuclear membrane that provides mechanical stability and plays important roles in processes such as transcription, DNA replication and chromatin organization. More than 300 mutations in lamin A/C have been associated with diverse clinical phenotypes, understanding the molecular basis of these diseases may provide a rationale for treating them. Here we describe the generation of induced pluripotent stem cells (iPSCs) from a patient with inherited dilated cardiomiopathy and 2 patients with distinct accelerated forms of aging, atypical Werner syndrome and Hutchinson Gilford progeria, all of which are caused by mutations in lamin A/C. These cell lines were pluripotent and displayed normal nuclear membrane morphology compared to donor fibroblasts. Their differentiated progeny reproduced the disease phenotype, reinforcing the idea that they represent excellent tools for understanding the role of lamin A/C in normal physiology and the clinical diversity associated with these diseases

Discovery of potential biomarkers for osteoporosis using LC/GC−MS metabolomic methods

PurposeFor early diagnosis of osteoporosis (OP), plasma metabolomics of OP was studied by untargeted LC/GC−MS in a Chinese elderly population to find possible diagnostic biomarkers.MethodsA total of 379 Chinese community-dwelling older adults aged ≥65 years were recruited for this study. The BMD of the calcaneus was measured using quantitative ultrasound (QUS), and a T value ≤-2.5 was defined as OP. Twenty-nine men and 47 women with OP were screened, and 29 men and 36 women were matched according to age and BMI as normal controls using propensity matching. Plasma from these participants was first analyzed by untargeted LC/GC−MS, followed by FC and P values to screen for differential metabolites and heatmaps and box plots to differentiate metabolites between groups. Finally, metabolic pathway enrichment analysis of differential metabolites was performed based on KEGG, and pathways with P ≤ 0.05 were selected as enrichment pathways.ResultsWe screened metabolites with FC&gt;1.2 or FC&lt;1/1.2 and P&lt;0.05 and found 33 differential metabolites in elderly men and 30 differential metabolites in elderly women that could be potential biomarkers for OP. 2-Aminomuconic acid semialdehyde (AUC=0.72, 95% CI 0.582-0.857, P=0.004) is highly likely to be a biomarker for screening OP in older men. Tetradecanedioic acid (AUC=0.70, 95% CI 0.575-0.818, P=0.004) is highly likely to be a biomarker for screening OP in older women.ConclusionThese findings can be applied to clinical work through further validation studies. This study also shows that metabolomic analysis has great potential for application in the early diagnosis and recurrence monitoring of OP in elderly individuals