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Characterization of Physico-Chemical Changes of Lignin Obtained under Different Conditions of Enzymatic Hydrolysis on an Industrial Scale

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Journal of Renewable Materials 2025年第1期13卷 115-126页

作者： Maris Lauberts janis Rizikovs Matiss Pals Karl Pebo Latvian State Institute of Wood Chemistry RigaLV-1006Latvia Fibenol OÜ Tallinn13522Estonia

Research-based on lignin as a bioproduct has grown due to its high availability,reactivity,physicochemical sta-bility,and abundance of different aromatic *** consists of various functional groups,which can react in various chemical reactions and serve as a raw material in various processes to obtain multiple *** characteristics make lignin suitable for synthesizing products from natural raw materials,replacing fossil *** to a high aromatic variety and complex structural arrangement,lignin isolation and fractionation are still *** aim and novelty of this work was the modiﬁcation of severity and enzymatic hydrolysis proce-dure on an industrial pre-treatment to improve by-products of birch processing as a raw material for the potential production of different *** from birch wood enzymatic hydrolysis was obtained and marked accord-ingly:HS(high severity),MS(medium severity),and LS(low severity)*** were characterized by ash content,analytical pyrolysis,solubility,and *** lignin was characterized by a relatively high carbohy-drate content(16%)and lower lignin content(77%).Meanwhile,LS lignin showed increased lignin content(83%)and reduced carbohydrate content(9%).It can be concluded that the deligniﬁcation process greatly inﬂu-ences the properties of the obtained *** lignin resulted in a lower polydispersity index(PDI)and more condensed structure,while LS lignin showed a higher PDI but a lower content of ***,look-ing for a golden middle way is necessary whileﬁnding the conditions according to the useﬁeld.

关键词： Lignin characterization environmental sustainable lignin-based materials

Evaluating the Potential of Birch Bark Suberinic Acids for Solid Wood Impregnation

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Journal of Renewable Materials 2025年第1期13卷 147-161页

作者： Daniela Godina Guntis Sosins Aigars Paze janis Rizikovs Raimonds Makars Andreas Treu Latvian State Institute of Wood Chemistry Biorefinery LaboratoryRigaLV-1006Latvia Norwegian Institute of Bioeconomy Research Department Wood TechnologyHøgskoleveien 8Ås1433Norway

Instead of the traditional linear model of taking,making,and disposing,the circular bio-economy promotes a regenerative *** there is potential to create valuable products like betulin,lupeol,and suberinic acids(SA)from outer birch bark,many industries,such as plywood and pulp,often choose to incinerate substan-tial amounts of leftover birch bark to meet their energy *** highlights the importance of obtaining valu-able products from *** objective of this study was to examine various fractions of SA and assess their potential for wood *** fractions included SA potassium salts in ethanol(SAK-EtOH)and water(SAK-H2O),SA suspension in water(SAS-H2O)and dried SA,which was subsequently diluted in ethanol(DSA-EtOH).There is signiﬁcant potential for utilizing SA in wood treatment formulations as a sustainable alternative to harmful petroleum-derived *** approach not only addresses environmental concerns but also enhances the functionality of wood in construction applications,such as improving impregnation for moisture and fungal *** the solutions tested,the ethanol solution of SA,speciﬁcally DSA-EtOH,showed the highest weight percent gain(WPG)and the greatest leaching *** analysis showed that SA salts in ethanol(SAK-EtOH)and water(SAK-H2O)predominantly consist of low molecular fractions and each process(acidiﬁcation and drying)reduces the low molecular content in the *** suggests that SA polymerizes after drying,making it necessary to dissolve it in ethanol to meet the requirements for *** opti-mization,including adjustments in the concentration of the SA ethanol solution and the curing temperature,is essential to identify the optimal conditions for more in-depth impregnation studies.

关键词： Birch bark suberinic acids solid wood impregnation

Conformal Composition for Borderline Fractional Sobolev Spaces

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Acta Mathematica Sinica,English Series 2025年第1期41卷 457-471页

作者： Nijjwal Karak pekka Koskela Debanjan Nandi Swadesh Kumar Sahoo Department of Mathematics Birla Institute of Technoogy and Science Pilani-Hyderabad CampusHyderabad 500078India Department of Mathematics and Statistics University of JyvèaskylèaP.O.Box 35FI-40014 JyvèaskylèaFinland Faculty of Mathematics and Computer Science Weizmann Institute of Science234 Herzl StreetRehovot 76100Israel Department of Mathematics Indian Institute of Technology IndoreIndore 453552India

We establish a pointwise property for homogeneous fractional Sobolev spaces in domains with non-empty boundary,extending a similar result of Koskela–Yang–*** use this to show that a conformal map from the unit disk onto a simply connected planar domain induces a bounded composition operator from the borderline homogeneous fractional Sobolev space of the domain into the corresponding space of the unit disk.

关键词： Besov Hajlasz–Triebel–Lizorkin hyperbolic conformal

Numerical simulation of three dimensional concrete printing based on a unified fluid and solid mechanics formulation

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Frontiers of Structural and Civil Engineering 2024年第4期18卷 491-515页

作者： janis REINOLD Koussay DAADOUCH Günther MESCHKE Institute for Structural Mechanics Ruhr University BochumBochum 44801Germany

Deformation control constitutes one of the main technological challenges in three dimensional(3D)concrete printing,and it presents a challenge that must be addressed to achieve a precise and reliable construction ***-based information of the expected deformations and stresses is required to optimize the construction process in association with the specific properties of the concrete *** this work,a novel thermodynamically consistent finite strain constitutive model for fresh and early-age 3D-printable concrete is *** model is then used to simulate the 3D concrete printing process to assess layer shapes,deformations,forces acting on substrate layers and prognoses of possible structural collapse during the layer-by-layer *** constitutive formulation is based on a multiplicative split of the deformation gradient into elastic,aging and viscoplastic parts,in combination with a hyperelastic potential and considering evolving material properties to account for structural buildup or *** advantage of this model is the stress-update-scheme,which is similar to that of small strain plasticity and therefore enables an efficient integration with existing material *** constitutive model uses the particle finite element method,which serves as the simulation framework,allowing for modeling of the evolving free surfaces during the extrusion *** analyses of three printed layers are used to create deformation plots,which can then be used to control the deformations during 3D concrete *** study offers further investigations,on the structural level,focusing on the potential structural collapse of a 3D printed concrete *** capability of the proposed model to simulate 3D concrete printing processes across the scales—from a few printed layers to the scale of the whole printed structure—in a unified fashion with one constitutive formulation,is demonstrated.

关键词： particle finite element method 3D concrete printing multiplicative split additive manufacturing elastoviscoplasticity

Sudoku of porous, injectable calcium phosphate cements – Path to osteoinductivity

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Bioactive Materials 2022年第11期7卷 109-124页

作者： Agneta Vezenkova janis Locs Rudolfs Cimdins Riga Biomaterials Innovations and Development Centre of RTU Institute of Genera Chemical EngineeringFaculty of Materials Science and Applied ChemistryRiga Technical UniversityPulka Street 3LV-1007RigaLatvia Baltic Biomaterials Centre of Excellence Headquarters at Riga Technical UniversityRigaLatvia

With the increase of global population,people’s life expectancy is growing as *** tend to live more active lifestyles and,therefore,trauma generated large defects become more *** of tumour resection or pathological conditions and complex orthopaedic issues occur more frequently increasing necessity for bone *** of calcium phosphate cements(CPCs)is comparable to the chemical structure of bone *** ability to self-set and resorb in vivo secures a variety of potential applications in bone *** the years-long research and several products already reaching the market,finding the right properties for calcium phosphate cement to be osteoinductive and both injectable and suitable for clinical use is still a *** article is focused on injectable,porous CPCs,reviewing the latest developments on the path toward finding osteoinductive material,which is suitable for injection.

关键词： Calcium phosphate cements Bone cements Bone regeneration Osteoinductivity

Mappings of Finite Distortion: Formation of Cusps Ⅲ

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Acta Mathematica Sinica,English Series 2010年第5期26卷 817-824页

作者： pekka KOSKELA Juhani TAKKINEN Department of Mathematics and Statistics University of Jyvskyl

We give sharp integrability conditions on the distortion of a planar homeomorphism that maps a standard cusp onto the unit disk.

关键词： cusp finite distortion planar homeomorphism

Sprayformed Hot Work Steels for Rapid Tooling

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Journal of Materials Science & Technology 2003年第z1期19卷 169-172页

作者： Yunfeng Yang Simo-pekka Hannula VTT Industrial Systems P.O.BOX 1703 FIN-02044 VTT Finland VTT Industrial Systems P.O.BOX 1703 FIN-02044 VTT Finland

The present work compares microstructures of hot work steels made by different processes, that is, by sprayforming,by casting, and a commercially supplied H13 steel. Material benefits are recognized by sprayforming hot working tools such as die inserts for hot forging. The sprayformed hot work steels present a fine and homogeneous microstructure,which implies that, at a similar toughness level, the sprayformed steel can be higher alloyed, so that the thermal fatigue and wear resistance at elevated temperatures can be improved. A series of steels with higher vanadium content than commercial hot work steels are developed. There are no segregation and carbide network problems usually encountered in conventional ingot/forging processed high-vanadium steels. Microstructure and hardness of the new sprayformed steels are studied under different heat treatment conditions. It is justified that these sprayformed steels can be directly used for tooling without high temperature hardening. Sprayforming the tool steels onto a precision ceramic mould is demonstrated to extend the technoeconomical benefits, so that a net shape production tool can be rapidly *** of the rapid tooling process are also discussed.

关键词： Rapid tooling, Sprayforming, Hot working steel, Die insert

Lebesgue points via the Poincar inequality

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Science China Mathematics 2015年第8期58卷 1697-1706页

作者： KARAK Nijjwal KOSKELA pekka Department of Mathematics and Statistics University of Jyvskyl

We show that in a Q-doubling space （X, d, μ）, Q 〉 1, which satisfies a chain condition, if we have a Q-Poincare inequality for a pair of functions （u, g） where g ∈ LQ（X）, then u has Lebesgue points 7-th-a.e. for h（t） = log1-Q-c（1/t）. We also discuss how the existence of Lebesgue points follows for u ∈ W1,Q（x） where （X, d, μ） is a complete Q-doubling space supporting a Q-Poincar; inequality for Q 〉 1.

关键词： Lebesgue point Poincar6 inequality Q-doubling space

Plasma-Chemical Synthesis of Nanosized Powders-Nitrides,Carbides,Oxides,Carbon Nanotubes and Fullerenes

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Plasma Science and Technology 2012年第11期14卷 980-995页

作者： Katerina ZAHARIEVA Gheorghi VISSOKOV janis GRABIS Slavcho RAKOVSKY Institute of Catalysis Bulgarian Academy of Sciences Institute of Inorganic Chemistry Riga Technical University

In this article the plasma-chemical synthesis of nanosized powders （nitrides, car- bides, oxides, carbon nanotubes and fullerenes） is reviewed. Nanosized powders - nitrides, carbides, oxides, carbon nanotubes and fullerenes have been successfully produced using different techniques, technological apparatuses and conditions for their plasma-chemical synthesis.

关键词： plasma nanosized powders nitrides carbides oxides carbon nanotubes,fullerenes