Degradable Foam Tray Based on High-concentration Dispersed Cellulose Fibers Obtained by a Hot-press Baking Process

Degradable industrial packaging foam trays made from cellulose fibers were fabricated using a hot-press baking process.Bleached softwood pulp fibers with a concentration of 30%were dispersed at a high speed under the action of a dispersant.The effects of the dispersant dosage of the fibers on the porosity,foam density,and static compression characteristics were discussed.Furthermore,the effects of the reinforcing adhesive including polyvinyl alcohol(PVA),and cassava starch on the physical and mechanical properties of the foam trays were studied,as well as the relationship between these properties and the microstructure of the foam trays.The dispersant enhanced the rheological and blistering properties of the fiber dispersion.As the dispersant dosage increased from 2%to 4%,the foam density gradually increased and the compressive strain performance and residual compressive strain of the foam trays decreased.Under the condition of constant dosage of dispersant,increasing the fiber proportion from 67%to 77%improved the porosity and foam density and slightly reduced the static compression performance.In additioton,the static compression resistance of the foamed materials was improved by increasing the PVA dosage since PVA was beneficial for improving the strength of the foam trays.

Research Status and Prospects of Bio-based Materials for Grease Barrier Coatings on Paper Food Packaging

Increased environmental and health concerns over the use of plastic packaging or fluorine-containing coatings,in combination with increased market demand for products with a longer shelf life,make bio-based materials one of the most important research candidates for alternative paper packaging materials for oil resistance.These bio-based materials have excellent oxygen and oil barriers,which are critical for food packaging.Moreover,they are biodegradable,naturally renewable,and safe.In this artical,two main groups of bio-based oil repellents for paper food packaging,including polysaccharide-based biopolymers and protein-based biopolymers,are enumerated,and the advantages and weaknesses of bio-based oil repellents are discussed,and effective solutions are proposed.Finally,research status and prospects on the development of bio-based oil-resistant coatings for the food packaging industry are presented.

Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.

Eco-friendly PVA/Kaolin Clay Coating for Barrier Paper

The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating. Oil impregnation and the addition of films may make the paper difficult to recycle or persistent in the environment owing to their strong binding force and nondegradability. Environmental concerns have attracted worldwide attention to eco-friendly barrier coatings. In this study, degradable polyvinyl alcohol(PVA) and kaolin clay pigment were used to prepare coatings that were applied to a base paper. By measuring the barrier properties of the coated paper, including the water absorptiveness(Cobb60 value), Hercules sizing degree, oil resistance(Kit rating), and water vapor transmission rate(WVTR), an optimal coating formulation and process were proposed. To examine the barrier mechanism of the PVA/kaolin clay coating, we characterized the coating microstructures using a scanning electron microscopy(SEM) and a mercury porosimeter. The results showed that the Cobb60 value and water vapor transmission rate of the coated paper decreased by 61.4% and 98.6%, respectively, compared with the base paper, for a pre-coating weight of 0.98 g/m^2 and a top-coating weight of about 3.23 g/m^2. Furthermore, the Hercules sizing degree rose by a factor of 337.2, while the oil resistance(Kit rating) increased from 0 to 12. The optimum drying temperature for a wet coating layer was found to be 170℃, and the optimum weight ratio of PVA to kaolin clay in the coating was determined to be 50∶50. It was assumed that the PVA/kaolin clay coating improved the smoothness of the paper considerably and decreased the pore size by filling the pores on the paper surface and forming an even film, thus enhancing the paper barrier performance. The coated paper also exhibited good repulpability.

Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

In this study,we investigated the barrier properties of different kinds of microfibrillated cellulose(MFC)coating layers.The air,oxygen,and water vapor permeability,as well as the water contact angles(WCA),were measured to quantify the barrier efficacy of the applied coatings.The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards.However,different MFC coatings realize different oxygen transmission rates(OTRs)and water vapor transmission rates(WVTRs).The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment(MFCCBP)gave the best oxygen and water vapor barrier performances.The OTR of the virgin cardboard(>16500 cm^(3)/(m^(2)·24 h))decreased to 4638 cm^(3)/(m^(2)·24 h)after coating with the MFCCBP.The WVTR similarly decreased from 1016.7 g/(m^(2)·24 h)to 603.2 g/(m^(2)·24 h).

Effects of MFC-modified GCC as Filler on the Opacity of Pulp Handsheets

Microfibrillated cellulose(MFC)was obtained by mechanical grinding of different pulps.MFC-modified ground calcium carbonate(GCC)was prepared in two different ways,designated MFC-GCC composite filler and MFC-GCC flocs filler.The opacity of pulp handsheets loaded with MFCmodified GCC was measured.The effects of MFC originated from different pulps,pretreatment method,and filler modification on the opacity of handsheets loaded with MFC-modified GCC were discussed.The results show that MFC originated from alkaline peroxide mechanical pulp(APMP)was optimal for improving the opacity of the handsheets and PFI grinding pretreatment for MFC provided a denser structure in the corresponding MFCAPMP-GCC floc filler while enzyme pretreatment was more effective in increasing the opacity of the filled paper.Under the experimental conditions,the opacity of handsheets increased from 81.0%to 82.7%when the unmodified GCC was replaced by an equivalent amount of MFCAPMP-GCC composite filler,while other properties were unchanged.

分布式办公下工作无边界化与员工主动行为的“过犹不及”关系研究

在越来越多企业实施分布式办公的背景下,工作和非工作领域间的边界愈发模糊,工作无边界化已经成为了一种普遍的工作特征。本研究基于情感认知评价理论,探究了工作无边界化影响员工主动行为的作用机制和边界条件。通过分析460份三时点匹配问卷发现:工作无边界化与员工主动行为之间存在倒U型关系,即工作无边界化对员工主动行为的影响存在“过犹不及”效应;工作无边界化与员工情感平衡之间存在倒U型关系,并通过情感平衡的中介作用对员工主动行为产生倒U型影响;员工的多任务处理倾向能够显著调节工作无边界化与情感平衡之间的倒U型关系,与低多任务处理倾向的员工相比,高多任务处理倾向的员工能够适应更高程度的工作无边界化和保持更高水平的情感平衡,工作无边界化对其情感平衡的负面影响也更低。本研究揭示了工作无边界化影响员工主动行为的内在机制和边界条件,研究结论有助于企业理解分布式办公下员工行为变化,也为企业进一步优化分布式办公模式提供了启发。

Protective Effect of Buyang Huanwu Decoction on Cerebral Ischemia/Reperfusion Injury by Inhibiting Autophagy Based on AMPK/UIK1Signaling Pathway

The aim of the paper is to explore whether AMPK/U1K1 signaling pathway is involved in regulating autophagy and alleviating cerebral ischemia/reperfusion(I/R)injury.On this basis,study the regulatory effect of Buyang Huanwu Decoction(BHD)on AMPK/U1K1 signaling pathway,aiming to clarify the molecular mechanism of BHD in alleviating cerebral I/R injury and the protective effect of BHD containing serum(BHDS)on OGD/R neurons.The research group adopted the following methods:Neurons cultured for 7 days in vitro were randomly divided into normal control group,model group(OGD/R),AMPK activator(AICAR)group(3 mmol/L),Buyang Huanwu Decoction medicated serum(BHDS)group(3%),Buyang Huanwu Decoction medicated serum+AMPK activator(BHDS+AICAR)group.The protein expressions of p-AMPK,AMPK,p-UlKl,U1K1,Beclin-1 and LC3B in neurons were detected by Western blot,the fluorescence intensity and apoptosis rate of neuron autophagosome CYTO-ID staining were detected by flow cytometry,the fluorescence intensity and morphological changes of neuron LC3B were detected by immunofluorescence double labeling method,the morphological changes of neurons were observed by inverted microscope,and the survival rate of neurons was detected by CCK-8 method.Neuron OGD/R model and the optimal concentration of BHDS.The neurons in the model group were subjected to hypoxia and glucose deprivation for 1 h,2 h,3 h,4 h and reoxygenation and glucose deprivation for 24 h.The survival rate of neurons and the release rate of 1DH to determine whether the model was successfully established.And the results show that BHDS group,the survival rate of OGD/R neurons was significantly increased,and the apoptosis rate was significantly decreased.Among them,3%BHDS intervention at the same time of hypoxia glucose deprivation for 3 h and reoxygenation glucose for 24 h was the best condition.In BHDS group,the levels of p-AMPK/AMPK,p-UlKl/UlKl,beclin-1,CYTO-ID and LC3B fluorescence intensity,and the transformation from LC3B-I to LC3B-II of OGD/R neurons were significantly decreased.So we can draw a conclusion that BHD can inhibit autophagy and alleviate cerebral I/R injury through AMPK/U1K1 signaling pathway.

什么导致了女性职业晋升障碍?一个基于多理论视角的整合模型

性别差距过大影响社会稳定和发展。女性职位晋升差距作为性别差距的重要表现受到了学术界的持续关注。本研究从理论视角和研究层面两个角度,系统梳理了国内外相关研究,将影响女性职位晋升的因素归纳为性别偏见、工作-家庭以及人力资本/社会资本三个理论视角,并从社会、组织和个体三个层面总结了不同理论视角下的影响因素,建立了影响女性职业晋升的因素和对策的多层次整合模型。在此基础上,提出了未来研究的几个方向。本文在理论上有助于研究者系统地了解影响女性职业晋升的因素以及这些因素在社会、组织和个体层面的具体表现;在实践方面有助于为社会和组织综合多方面因素制定联动政策,进而缩小职业晋升的性别差距。该研究也为女性自身克服社会、组织因素和自身的心理障碍的影响提供启发。

Energy transfer,superior thermal stability and multi-color emitting properties of langbeinite-type solid-solution phosphor K_(2)Dy_(1.5-x)Eu_(x)Ta_(0.5)(PO_(4))_(3)

Langbeinite type compounds are a large kind of oxometallate with good flexibility structure.Herein,we synthesized a new langbeinite type compound K_(2)Dy_(1.5)Ta_(0.5)(PO_(4))_(3),in which the Dy^(3+)and Ta^(5+)were blended to occupy the same crystallographic sites.Simultaneously,solid solutions of K_(2)Dy_(1.5-x)Eu_(x)Ta_(0.5)(PO_(4))_(3)(x=0-1.5)were prepared and their photoluminescence properties were investigated.Due to energy transfer from Dy3+to Eu3+,both Dy3+and Eu3+characteristic emissions are observed under 393 nm light excitation.The emitting color of K_(2)Dy_(1.5-x)Eu_(x)Ta_(0.5)(PO_(4))_(3)turns from green through yellow to red by simply adjusting the Eu^(3+)concentration from 0 to 0.4.Moreover,K_(2)Dy_(1.48)Eu_(0.02)Ta_(0.5)(PO_(4))_(3)phosphor possesses excellent fluorescence thermal stability and exhibits zero thermal quenching at 150℃.These results manifest that K_(2)Dy_(1.5-x)Eu_(x)Ta_(0.5)(PO_(4))_(3)solutions are promising multi-color emitting phosphors candidate for near-UV LED.