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Abstract Sulfonated poly (ether ether ketone) (SPEEK) has received substantial attention for its potential to improve the electrochemical behavior and thermomechanical capabilities of direct methanol fuel cells. This study examines how the integration by solution casting of microcrystalline cellulose (MCC) and 2,3-dialdehyde cellulose (DAC) onto highly sulfonated PEEK (with a sulfonation degree of 80%) affects its physicochemical properties and morphological structures. The mechanical attributes and proton conductivity of the polymer matrix are impacted by MCC and DAC inclusion into SPEEK membrane. The maximum proton conductivity was seen in the SPEEK/MCC membranes at 70 °C (up to 0.1 S cm−1). The proton conductivity in methanol vapor was increased by SPEEK/DAC membranes at high temperatures as opposed to pristine SPEEK and SPEEK/MCC membranes.

The layer-by-layer (LbL) assembling of oppositely charged polyelectrolytes was studied using semi-synthetic polysaccharide derivatives, namely the polycations 6-aminoethylamino-6-deoxy cellulose (ADC) and cellulose (2-(ethylamino)ethylcarbamate (CAEC), as well as the polyanion cellulose sulfate (CS). The synthetic polymers poly(allylamine) (PAH) and poly(styrene sulfonate) (PSS) were employed as well for comparison. The stepwise adsorption process was monitored by whispering gallery mode (WGM) experiments and zeta-potential measurements. Distinct differences between synthetic- and polysaccharide-based assemblies were observed in terms of the quantitative adsorption of mass and adsorption kinetics. The LbL-approach was used to prepare µm-sized capsules with the aid of porous and non-porous silica particle templates. The polysaccharide-based capsule showed a switchable permeability that was not observed for the synthetic polymer materials. At ambient pH values of 7, low-molecular dyes could penetrate the capsule wall while no permeation occurred at elevated pH values of 8. Finally, the preparation of protein-loaded LbL-capsules was studied using the combination of CAEC and CS. It was shown that high amounts of protein (streptavidin and ovomucoid) can be encapsulated and that no leaking or disintegration of the cargo macromolecules occurred during the preparation step. Based on this work, potential use in biomedical areas can be concluded, such as the encapsulation of bioactive compounds (e.g., pharmaceutical compounds, antibodies) for drug delivery or sensing purposes.

The goal of this study was to explore a route for introducing functionalities into agarose-based hydrogels to tune the physical, chemical, and biological properties. Several agarose derivatives were prepared by homogeneous synthesis, including anionic agarose sulfates (ASs), reactive azido agaroses (AZAs), and cationic agarose carbamates (ACs), as well as agarose tosylates (ATOSs) and agarose phenyl carbonates (APhCs). The products were characterized in terms of their molecular structure and solubility behavior. The results suggest that the native gel-forming ability of agarose is retained if the introduced functionalities are hydrophilic, and the overall degree of substitution is low (DS < 0.5). Thus, functional hydrogels from several agarose derivatives could be obtained. The mechanical stability of the functional hydrogels was decreased compared to native agarose gels but was still in a range that enables safe handling. An increase in mechanical strength could be achieved by blending functional agarose derivatives and agarose into composite hydrogels. Finally, it was demonstrated that the novel functional agarose hydrogels are biocompatible and can potentially stimulate interactions with cells and tissue.

The major highway in Sri Lanka that links the capital, Colombo, with the second capital, Kandy, passes through Kadugannawa, characterized by steep hills. The geological and geomorphological setting of the terrain often leads to slope failures. The objective of this study is to interpret the key factors influencing the slope failures that occurred in close proximity at two separate locations with two different slope conditions. Typical local and regional brittle and ductile structures include fault scarps, deep-seated detachments, and variable folding. According to our results, one of the studied locations experienced translational landslides because of weakened basement rock surfaces, hydrophilic clay minerals, and anthropogenic influences, whereas the other location experienced multiple stages of mass movement influenced by inhomogeneous colluvial soil and regional, geological, and hydrogeological conditions. Based on the present study, it can be concluded that geological studies must be carried out within the local area rather than at the regional scale. Otherwise, the constructions for the prevention of landslides in complicated geological settings will fail or may not be used for a long period. Moreover, consideration of future climate change is essential when undertaking construction in challenging terrains.

Abstract Stimulation techniques to enhance fluid pathways are an important tool to make geothermal projects economically feasible. So far, hydraulic stimulation is used almost exclusively for reservoir-wide improvement of the permeability, but induced seismicity poses a challenge. Chemical stimulation on the other hand has been limited to the close vicinity of the borehole and has barely been considered for the creation of enhanced geothermal reservoirs. However, retardation mechanisms reducing the chemical reaction rate can be used to increase the radius of the chemical stimulation thus enabling a reservoir-wide enhancement of fluid pathways. In this work, we review the technologies of retardation mechanisms for chemical stimulation in geothermal systems and identify five groups of retardation techniques: (i) causing impaired mobility of the acid, e.g., by gelling agents; (ii) causing an impaired dissociation, e.g., by the in-situ generation of the reactive compounds; (iii) blocking the mineral surface area, e.g., by alternating injections of pad fluids and acids; (iv) reducing the reaction rate constant, e.g., by cooling; and (v) changing the chemical equilibrium through chelating agents. We found that most applications are currently based on the use of impaired dissociation, but present research focuses on the development and application of chelating agents. Most of these retardation techniques are adopted from the hydrocarbon industry, but there are several techniques that have not been applied in the geothermal context so far for various reasons. We identify a distinctive lack of in-depth descriptions of the retardation techniques in various studies—mostly to protect intellectual property. However, in the light of public concern regarding fracking techniques and to independently assess potential environmental hazards, scientific examination of proposed techniques is indispensable.

Polysaccharide derivatives with two types of functionalities were synthesized; reactive groups for click-chemistry approaches and groups that can tune the water solubility of the products. Xylan phenylcarbonates (XPCs) and cellulose phenylcarbonates (CPCs) with degrees of substitution (DS) ranging from 0.6 to 3.0 were prepared as starting materials. In a modular synthesis approach, these carbonate derivatives were converted with different amines to obtain functional xylan carbamates (XCs) and cellulose carbamates (CCs) with (i) reactive alkynyl- or furfuryl groups and / or (ii) hydrophilic hydroxyalkyl or tertiary amino groups. Both types of functionalities were introduced separately or simultaneously in a convenient one-pot-approach. Mixed polysaccharide carbamates with low, intermediate, and high DS values (0.6 to 2.5) were successfully prepared and characterized. The water solubility of the carbamates and mixed carbamates was tuned by variation of the type and DS of the two hydrophilic substituents. Surprisingly, some of the products showed lower or upper critical solution temperatures (LCSTs, UCSTs). Thus, the thermoreversible phase transition in aqueous solutions was studied. The products obtained in this work are very promising for the preparation of hydrogels through selective covalent crosslinking as well as for the fabrication of thermoresponsive biomaterials.

The functionalization pattern in polysaccharide derivatives is an important factor that determines their properties and, thus, their functions in applications. Regioselectively functionalized polysaccharide derivatives are used in material science because they may form lamellar structures in microscale by self-assembling. Intrinsically chiral polysaccharide derivatives are used for the separation of enantiomers by chromatography, and the separation efficiency is influenced by the regioselective distribution of substituents attached. Due to the multi-functionality of polysaccharides, their derivatization reactions usually yield products with random distribution of substituents. Thus, establishment of unambiguous structure-property relationships cannot be achieved. This review article summarizes recent developments in this topic. In addition to the blocking group techniques, synthesis methods applying activating substituents will be summarized. Moreover, the reaction medium itself may direct the substituent in a certain position without laborious multistep reactions.

Bacterial cellulose has superior physical and chemical properties, biocompatibility, and purity. However, the high production cost obstructs the common use of this polymer. This study investigated the efficiency of olive pomace, an important by-product of olive oil industry in Turkey, as a carbon source for Novacetimonas hansenii. Olive pomace pretreatment with 1% H3PO4 was followed by enzymatic hydrolysis. The maximal reducing sugar concentration upon enzymatic process was 9.3 g/L with 1 enzyme: 6 substrate (dry matter) ratio. After incubation in the growth media prepared with the obtained reducing sugar as carbon source, the highest bacterial cellulose production was 0.68 g/L. Structural analysis indicated that bacterial cellulose from the enzymatic media and the conventional Hestrin-Schramm medium possess similar characteristics. The present work provides a favourable method to reduce the cost of bacterial cellulose production.

Heat transfer in a fracture network is heterogeneous as it depends pre-dominantly on flow velocity and fracture aperture. This finding has direct implications for the heat distribution and exploitation in geothermal and associated natural systems.

This review article is dedicated to special polysaccharide esters – the polysaccharide toluenesulfonic acid esters (tosylates) and polysaccharide carbonate esters. After describing the specifics of the synthesis, particular emphasis is placed on the use of polysaccharide tosylates and polysaccharide phenyl carbonates for subsequent modification by nucleophilic substitution (SN) reactions. For this purpose, the advantages and limitations of the respective derivatives are discussed with regard to their application in chemical modification with nucleophiles containing functional groups. A few functional polysaccharide derivatives and their properties are presented. Finally, reactive derivatives for click chemistry approaches are featured. These can be prepared starting from the reactive intermediate of either polysaccharide tosylate or polysaccharide phenyl carbonate.

Methyl cellulose and its derivatives are widely used in the food industry, cosmetics, and as construction materials. The properties of methyl celluloses (MC) strongly depend on their degrees and positions of substitution. In order to generate MCs with uncommon blocky substitution, we apply fully protected O-benzyl-O-methyl celluloses (BnMC). Such complex polysaccharide derivatives could not be deprotected completely and without shift of the composition by methods usually applied to mono- and oligosaccharides. Therefore, a facile debenzylation method was developed based on photo-initiated free-radical bromination in the presence of hydrobromic acid scavengers followed by alkaline treatment. The reaction proceeds under homogeneous conditions and without the aid of any catalyst. There is no need for expensive equipment, materials, anhydrous reagents, or running the reaction under anhydrous conditions. Reaction parameters were investigated and optimized for successful debenzylation of completely protected BnMC with degrees of methyl substitution (DSMe) around 1.9 (and DSBn around 1.1). Side-product-free and almost complete debenzylation was achieved when 1,2-epoxybutane (0.5 eq./eq. N-bromosuccinimide) and 2,6-di-tert-butylpyridine (0.5 eq./eq. N-bromosuccinimide) were used in the reaction. Furthermore, ATR-IR and 1H NMR spectroscopy confirmed the successful removal of benzyl ether groups. The method was developed to monitor the transglycosylation reaction of the BnMC with permethylated cellulose, for which the deprotection of many small samples in parallel is required. This comprises the determination of the methyl pattern in the glucosyl units by gas-liquid chromatography (GLC), as well as oligosaccharide analysis by liquid chromatography mass spectrometry (LC-MS) after perdeuteromethylation and partial hydrolysis to determine the methyl pattern in the chains. The unavoidable partial chain degradation during debenzylation does not interfere with this analytical application, but, most importantly, the DS and the methyl pattern were almost congruent for the debenzylated product and the original MC, indicating the full success of this approach The presented method provides an unprecedented opportunity for high throughput and parallel debenzylation of complicated glucans, such as BnMC (as a model compound), for analytical purposes. For comparison, debenzylation using Na/NH3 was applied to BnMC and resulted in a completely debenzylated product with a remarkably high recovery yield of 99 mol% and is, thus, the method of choice for synthetic applications, e.g., for the transglycosylation product prepared under the selected conditions in a preparative scale.

Thermoplastics are an important class of polymers that find widespread use in a broad variety of applications. Because of environmental concerns regarding the lack of biodegradability of synthetic thermoplastics, green alternatives are increasingly studied that should be both based on renewable resources and biodegradable. In this regard, polysaccharide esters of naturally occurring fatty acids are in the center of interest.

RNA interference can be applied to different target genes for treating a variety of diseases, but an appropriate delivery system is necessary to ensure the transport of intact siRNAs to the site of action. In this study, cellulose was dually modified to create a non-viral vector for HDAC3 short interfering RNA (siRNA) transfer into cells. A guanidinium group introduced positive charges into the cellulose to allow complexation of negatively charged genetic material. Furthermore, a biotin group fixed by a polyethylene glycol (PEG) spacer was attached to the polymer to allow, if required, the binding of targeting ligands. The resulting polyplexes with HDAC3 siRNA had a size below 200 nm and a positive zeta potential of up to 15 mV. For N/P ratio 2 and higher, the polymer could efficiently complex siRNA. Nanoparticles, based on this dually modified derivative, revealed a low cytotoxicity. Only minor effects on the endothelial barrier integrity and a transfection efficiency in HEK293 cells higher than Lipofectamine 2000TM were found. The uptake and release of the polyplexes were confirmed by immunofluorescence imaging. This study indicates that the modified biopolymer is an auspicious biocompatible non-viral vector with biotin as a promising moiety.

Sulfobetainic polymers were synthesized by polymeranalogous reaction of new amino celluloses starting from cellulose tosylate. To obtain different amino celluloses as starting building blocks, a comprehensive study with a selection of asymmetric and symmetric N-alkylated diamines was performed. For reaction with asymmetric diamines, it turned out that the primary amino moiety reacts preferably. Derivatives thus obtained consist in a neutral main structural unit and a cationic side structural unit, which is not described up to now. In order to investigate the reactivity of the amino celluloses 6-deoxy-6-(N,N,N′,N′-tetramethylethylenediamino) cellulose was used as uniform starting material for the design of novel polyampholytes by conversion with 1,3-propansultone. Detailed structure characterization was implemented by means of 1D and 2D-NMR spectroscopy.

Pectin, as a sustainable biopolymer with its two complementary functionalities (carboxyl and hydroxyl moieties) imparted in the α-1,4-galacturonic acid repeating unit, has gained increasing attention in the last few years. The interest in this ubiquitously occurring plant originating polysaccharide (PS) has shifted slowly from applications as a food additive to a broader range of potential applications in medicine, cosmetics, and other industries. Due to the increasing interest in alternatives for petrochemical materials, PSs as biomaterials have gained increasing attention in industrial processes in general. In the last decade, an increasing number of chemical transformations related to pectin have been published, and this is a prerequisite for the design of the structure and hence properties of novel biopolymer-based materials. This work aims to review the chemical modifications of pectin by covalent linkage of the last decade and analyze the materials obtained with these chemical methods critically.

Biosynthetically produced α-1,3-glucan dissolved in N,N-dimethyl acetamide/LiCl was allowed to react with lauric-, palmitic-, and stearic acid in presence of the activation agents p-toluenesulfonic acid chloride (TsCl), N,N′-carbonyldiimidazole (CDI), or the iminium chloride (ImCl) obtained from N,N-dimethyl formamide and oxalyl chloride. The highest degree of substitution (DS) of ester groups of 2.20 was obtained by reacting the glucan with 5 mol lauric acid and 5 mol ImCl per mole repeating unit within for 4 h at 100 °C. Formation of 6-deoxy-6-chloro moieties (as a known side reaction) is less pronounced in case of ImCl compared the use of TsCl for activation. The glucan esters melt except those synthesized with CDI as activation agent. The melting temperature is lower in case of higher DS, longer carboxylic acid, and lower molar mass. Products which do form a melt were shaped to films and could be used as basis for hot-melt adhesive to bond wood.

α-1,3-Glucan benzoates (GB) were prepared by homogeneous derivatization of the polysaccharide in N,N-dimethylacetamide (DMA)/LiCl using either benzoyl chloride as reagent (without and with addition of pyridine) or benzoic acid (using 1,1′-carbonyldiimidazole (CDI) for in situ activation of the carboxyl groups). A maximum degree of substitution (DS) of 1.96 was achieved by adjusting reaction time and molar ratio of reagent to anhydroglucose unit (AGU). The esterification with aromatic benzoate moieties was demonstrated by FTIR- and NMR spectroscopy. Substitution predominately occurred at the primary C-6 position with an order of reactivity of C6 » C2 > C4. The novel GB were soluble in dipolar aprotic solvents starting at DS ≥ 0.5 and melt at temperatures around 190 °C provided the DS is ≥ 1.7. Keywords: α-1,3-Glucan, Polysaccharide benzoates, Homogeneous derivatization, Esterification, NMR spectroscopy

Amino celluloses are semisynthetic polysaccharide derivatives that are functionalized with amino groups. This class of bio-based polymers has a number of interesting properties for advanced applications such as potential antimicrobial activity and pronounced surface affinity towards various materials. Herein, the synthesis of a novel type of 6-deoxy-6-amino cellulose derivatives with a polar and highly branched substituent (2-amino-2-(hydroxymethyl)propane-1,3-diol/TRIS) is described for the first time. Fundamental principles for the synthesis by nucleophilic displacement of tosylated intermediates are highlighted, thus, providing access to materials with well-defined molecular structures. TRIS-functionalized cellulose derivatives with degrees of substitution (DS) of up to 0.5 were obtained. The solubility and rheological properties of the products showed a strong dependence on the pH value. Due to the unique structural features of the substituent, TRIS amino cellulose derivatives possess a high application potential. Keywords: Amino celluloses, Water soluble polysaccharide derivatives, 2-Amino-2-(hydroxymethyl)propane-1,3-diol, Nucleophilic displacement, NMR spectroscopy

AbstractThis paper argues that quantitative science studies should frame their data and analyses with middle-range sociological theories and concepts. We illustrate this argument with reference to the “sociology of professions,” a middle-range theoretical framework developed by Chicago sociologist Andrew Abbott. Using this framework, we counter the claim that the use of bibliometric indicators in research assessment is pervasive in all advanced economies. Rather, our comparison between the Netherlands and Italy reveals major differences in the national design of bibliometric research assessment: The Netherlands follows a model of bibliometric professionalism, whereas Italy follows a centralized bureaucratic model that co-opts academic elites. We conclude that applying the sociology of professions framework to a broader set of countries would be worthwhile, allowing the emerging bibliometric profession to be charted in a comprehensive, and preferably quantitative, fashion. We also briefly discuss other sociological middle-range concepts that could potentially guide empirical analyses in quantitative science studies.

We present a novel and generalised notion of doping cleanness for cyber-physical systems that allows for perturbing the inputs and observing the perturbed outputs both in the time- and value-domains. We instantiate our definition using existing notions of conformance for cyber-physical systems. As a formal basis for monitoring conformance-based cleanness, we develop the temporal logic HyperSTL*, an extension of Signal Temporal Logics with trace quantifiers and a freeze operator. We show that our generalised definitions are essential in a data-driven method for doping detection and apply our definitions to a case study concerning diesel emission tests.

Nanoparticles have a great prospect for therapeutic applications. They can protect drugs under physiological conditions and act as a matrix for directed delivery of drugs, e.g., to a specific tissue or cell type. Polymer-based nanomaterials are considered as highly effective in this regard. Their properties can be tailored to meet specific demands for given therapeutic purposes. Considering the high-quality standards placed on medical products, the question arises: Which type of polymer material should be employed? One might select synthetic polymer compounds, which are highly diverse in terms of the molecular structures and supramolecular architectures that can be created, or biopolymers such as polysaccharides that are renowned for their native biocompatibility.

Geoelectrical methods can be part of early warning systems for landslide-prone hillslopes by giving estimates of the water content distribution. Structurally constrained inversions of geoelectrical data can improve the water content estimation by reducing the smoothness constraint along known lithological boundaries, which is especially important for landslides, as often layers with strongly divergent hydrological parameters and varying electrical signatures are present in landslides. However, any a priori information about those boundaries has an intrinsic uncertainty. A detailed synthetic study and a field investigation are combined to study the influence of misplaced structural constraints and the strength of the smoothness reduction via a coupling coefficient on inversion results of electrical resistivity data. While a well-known lithological boundary with a substantial reduction of the smoothness constraint can significantly improve the inversion result, a flawed constraint can cause strong divergences from the synthetic model. The divergence can even grow above the divergence of a fully smoothed inversion result. For correctly placed structural constraints, a coupling coefficient smaller than 10−4 uncovers previously unseen dynamics in the resistivity distribution compared to smoothed inversion results. Uncertain layer boundaries can be included in the inversion process with a larger coupling coefficient to avoid flawed results as long as the uncertainty of the layer thickness is below 20%. The application to field data confirms these findings but is less sensitive to a further reduction of the coupling coefficient, probably due to uncertainties in the structural information.

Scientific and/or technical breakthroughs require the exploration of novel ideas and technologies. Yet, it has not been studied quantitatively how national institutional contexts either facilitate or stifle organizational support for exploration. Available qualitative evidence suggests that institutional contexts that exert weak control over universities and research organizations strengthen their capabilities to achieve scientific breakthroughs, while contexts with strong control constrain them. The paper is based on an analysis of the population of Nobel laureates in Physics, Chemistry and Physiology or Medicine. We examine to what extent existing qualitative findings for the biomedical sciences, which are partly based on Nobel laureates in Physiology or Medicine, can be substantiated both quantitatively and across the three Nobel Prize fields of science. We find that for most of the 20th century and the early 21st century, countries with weak institutional control (United Kingdom, United States) have outperformed those exerting strong control (France, Germany). These results are further corroborated when controlled by population sizes and by GDP per capita. In addition, these results hold not only for the biomedical sciences, but also for Physics and Chemistry. Furthermore, countries with weak institutional control have attracted many future Nobel laureates from countries with strong environments. In this regard, the United States appears to be a particularly attractive setting for conducting innovative research, and thus has been a magnet for young and promising scientists. However, future laureates working in institutional environments exerting weak control are not faster in accomplishing their prize-winning work compared to those laureates working in more restrictive institutional settings.

Climate change is already affecting high mountain regions, such as the European Alps. Those regions will be confronted with a significant rise of temperatures above the global average, and more and heavier rain events, also during wintertime. The system response to the coincidence of rain, snow, and possibly frozen soil depends on the almost infinite number of possible combinations of thermo-hydraulic states of the involved phases. Landslides, snow avalanches, debris flows, or extensive surface runoff are just a few of the possible hazardous outcomes. With rising temperatures and increased precipitation, those hazardous outcomes are expected to occur even more frequently in the future, requiring a better understanding of those coupled processes for hazard mitigation strategies. The macroscopic phenomena are controlled by porescale processes, such as water freezing and ice grains blocking pores, which are only barely understood. The strong coupling between thermal state and hydraulic parameters, the possible phase change, and material heterogeneity pose great challenges for investigation. This work provides an overview of documented hazard events regarding rain, snow, and possibly frozen soil. The current state in theoretical and experimental research is presented before several knowledge gaps are derived and possible techniques to address those gaps are discussed.

Starch can be efficiently converted into the corresponding formates homogeneously using N-formyl imidazole obtained by the reaction of 1,1′-carbonyldiimidazole and formic acid in dimethyl sulfoxide as a solvent. Starch formates are soluble in polar aprotic solvents, not susceptible against hydrolysis, and not meltable. Thermoplastics could be generated by conversion of starch formates with long-chain fatty acids exemplified by the conversion with lauroyl chloride in N,N-dimethylacetamide, leading to mixed starch laurate formates. The mixed esters show melting temperatures mainly dependent on the amount of laurate ester moieties.

Polysaccharide (PS) based nanoparticles (NP) are of great interest for biomedical applications. A key challenge in this regard is the functionalization of these nanomaterials. The aim of the present work was the development of reactive PS-NP that can be coupled with an amino group containing compounds under mild aqueous conditions. A series of cellulose phenyl carbonates (CPC) and xylan phenyl carbonates (XPC) with variable degrees of substitution (DS) was obtained by homogeneous synthesis. The preparation of PS-NP by self-assembling of these hydrophobic derivatives was studied comprehensively. While CPC mostly formed macroscopic aggregates, XPC formed well-defined spherical NP with diameters around 100 to 200 nm that showed a pronounced long-term stability in water against both particle aggregation as well as cleavage of phenyl carbonate moieties. Using an amino group functionalized dye it was demonstrated that the novel XPC-NP are reactive towards amines. A simple coupling procedure was established that enables direct functionalization of the reactive NP in an aqueous dispersion. Finally, it was demonstrated that dye functionalized XPC-NP are non-cytotoxic and can be employed in advanced biomedical applications.

Based on the entire population of Nobel laureates in science from 1901 to 2017, we show that North America's rise as global power in science started in the 1920s. Following a transition period (1940s to 1960s), its scientific hegemony was consolidated in the 1970s. Yet since the 2000s, North America's global leadership in science has come under pressure. In that time, its share of laureates across disciplines dropped, although it has retained its attractiveness as a destination for future laureates from Europe and the Asia-Pacific region. In addition, we find that North America has become apparently less effective since 2010 in transferring capacities for conducting ground-breaking research from one generation of scientists to another. Furthermore, both Europe and the Asia-Pacific region have similarly high shares of newcomer organizations with regard to where prize-winning work is conducted, indicating that these two regions are very active in the inter-organizational competition for scientific talent. Despite this competition, however, we find no support for the rise of a new global center of science.

[This corrects the article DOI: 10.1371/journal.pone.0213916.].

Rainfall-induced landslides are a disastrous natural hazard causing loss of life and significant damage to infrastructure, farmland and housing. Hydromechanical models are one way to assess the slope stability and to predict critical combinations of groundwater levels, soil water content and precipitation. However, hydromechanical models for slope stability evaluation require knowledge about mechanical and hydraulic parameters of the soils, lithostratigraphy and morphology. In this work, we present a multi-method approach of site characterization and investigation in combination with a hydromechanical model for a landslide-prone hillslope near Bonn, Germany. The field investigation was used to construct a three-dimensional slope model with major geological units derived from drilling and refraction seismic surveys. Mechanical and hydraulic soil parameters were obtained from previously published values for the study site based on laboratory analysis. Water dynamics were monitored through geoelectrical monitoring, a soil water content sensor network and groundwater stations. Historical data were used for calibration and validation of the hydromechanical model. The well-constrained model was then used to calculate potentially hazardous precipitation events to derive critical thresholds for monitored variables, such as soil water content and precipitation. This work introduces a potential workflow to improve numerical slope stability analysis through multiple data sources from field investigations and outlines the usage of such a system with respect to a site-specific early-warning system.

Alpha- and beta-linked 1,3-glucans have been subjected to conversion with p-toluenesulfonic acid (tosyl) chloride and triethylamine under homogeneous reaction conditions in N,N-dimethyl acetamide/LiCl. Samples with a degree of substitution of tosyl groups (DSTs) of up to 1.91 were prepared by applying 5 mol reagent per mole repeating unit. Hence, the reactivity of α-1,3-glucan is comparable with cellulose and starch, while the β-1,3-linked glucan curdlan is less reactive. The samples dissolve in aprotic dipolar media independent of the DSTs and possess a solubility in less polar solvents that depends on the DSTs. NMR studies on the tosyl glucans and of the peracylated derivatives showed a preferred tosylation of position 2 of the repeating unit. However, the selectivity is less pronounced compared with starch. It could be concluded that the α-configurated glycosidic bond directs tosyl groups towards position 2.

Flow and transport processes in fractured systems are not yet fully understood, and it is challenging to determine the respective parameters experimentally. Studies on 10 samples of 2 different sandstones were used to evaluate the reproducibility of tracer tests and the calculation of hydraulic transport properties under identical boundary conditions. The transport parameters were determined using the advection–dispersion equation (ADE) and the continuous time random walk (CTRW) method. In addition, the fracture surface morphology and the effective fracture aperture width was quantified. The hydraulic parameters and their variations were studied for samples within one rock type and between both rock types to quantify the natural variability of transport parameters as well as their experimental reproducibility. Transport processes dominated by the influence of fracture surface morphology experienced a larger spread in the determined transport parameters between repeated measurements. Grain size, effective hydraulic aperture and dispersivity were identified as the most important parameters to evaluate this effect, as with increasing fracture aperture the effect of surface roughness vanishes and the experimental reproducibility increases. Increasing roughness is often associated with the larger effective hydraulic aperture canceling out the expected increased influence of the fracture surface morphology.

In single fractures, dispersion is often linked to the roughness of the fracture surfaces and the resulting local aperture distribution. To experimentally investigate the effects of diverse fracture types and surface morphologies in sandstones, three fractures were considered: those generated by sawing and splitting, and a natural sedimentary fracture. The fracture surface morphologies were digitally analyzed and the hydraulic and transport parameters of the fractures were determined from Darcy and the tracer tests using a fit of a continuous time random walk (CTRW) and a classical advection–dispersion equation (ADE). While the sawed specimen with the smoothest surface had the smallest dispersivity, the natural fracture has the largest dispersivity due to strong anisotropy and non-matching fracture surfaces, although its surface roughness is comparable to the split specimen. The parameterization of the CTRW and of the ADE agree well for β > 4 of the truncated power law. For smaller values of β, non-Fickian transport processes are dominant. Channeling effects are observable in the tracer breakthrough curves. The transport behavior in the fractures is controlled by multiple constraints such as several surface roughness parameters and the equivalent hydraulic aperture.

Due to the increase of the organic cultivation of beetroot and its growing importance as a functional food, the potential advantages of open-pollinated genotypes as an alternative for F1 hybrid genotypes has been investigated. In this regard, six field experiments were carried out in 2017 and 2018 in three different locations to investigate the agronomic potential of new and existing open-pollinated genotypes of beetroot and their performance under the specific conditions of organic agriculture. Fifteen beetroot genotypes, including one F1 hybrid as a commercial control and one breeding line, were compared regarding their total and marketable yield, individual beet weight, diameter of beet, and leaves-growth-base width. Furthermore, five randomly selected beetroots meeting common marketable criteria were evaluated optically with regard to skin smoothness, corky surface, root tail, scab incidence, and uniformity. Results of this study indicated a significant impact of genotype on eight of the assessed traits. The cylindrical-shaped genotype, Carillon RZ, demonstrated significantly higher total and marketable yields, with 53.28 ± 3.34 t ha−1 and 44.96 ± 3.50 t ha−1, respectively, compared to the yellow-colored genotype, Burpees Golden, which obtained the lowest total yield, 36.06 ± 3.38 t ha−1, and marketable yield, 27.92 ± 3.55 t ha−1. Moreover, the comparison of the open-pollinated genotypes with the F1 hybrid, Monty RZ F1, revealed that except for the traits yield, scab, and uniformity, the open-pollinated genotypes indicated desirable competitive outcomes and thus offer suitable alternatives for organic cropping systems. Overall, the observed genetic variability can be beneficial for breeding and food product development.

The use of bibliometric measures in the evaluation of research has increased considerably based on expertise from the growing research field of evaluative citation analysis (ECA). However, mounting criticism of such metrics suggests that the professionalization of bibliometric expertise remains contested. This paper investigates why impact metrics, such as the journal impact factor and the h-index, proliferate even though their legitimacy as a means of professional research assessment is questioned. Our analysis is informed by two relevant sociological theories: Andrew Abbott's theory of professions and Richard Whitley's theory of scientific work. These complementary concepts are connected in order to demonstrate that ECA has failed so far to provide scientific authority for professional research assessment. This argument is based on an empirical investigation of the extent of reputational control in the relevant research area. Using three measures of reputational control that are computed from longitudinal inter-organizational networks in ECA (1972-2016), we show that peripheral and isolated actors contribute the same number of novel bibliometric indicators as central actors. In addition, the share of newcomers to the academic sector has remained high. These findings demonstrate that recent methodological debates in ECA have not been accompanied by the formation of an intellectual field in the sociological sense of a reputational organization. Therefore, we conclude that a growing gap exists between an academic sector with little capacity for collective action and increasing demand for routine performance assessment by research organizations and funding agencies. This gap has been filled by database providers. By selecting and distributing research metrics, these commercial providers have gained a powerful role in defining de-facto standards of research excellence without being challenged by expert authority.

A novel polyzwitterion possessing weak ionic groups could be efficiently synthesized from cellulose phenyl carbonate. Polyanion, polycation, and polyzwitterion are accessible by orthogonal removal of protecting groups. The molecular structure was proofed by FTIR- and NMR spectroscopy. Characteristic properties of the cellulose derivatives, e.g., acid dissociation constants, isoelectric point and complexation, were investigated by potentiometric titration (pH), nephelometry, rheology and dynamic light-scattering. The formation of pH-responsive interpolyelectrolyte complexes applying polydiallyldimethylammonium chloride was preliminary studied.

Healing of large bone defects requires implants or scaffolds that provide structural guidance for cell growth, differentiation, and vascularization. In the present work, an agarose-hydroxyapatite composite scaffold was developed that acts not only as a 3D matrix, but also as a release system. Hydroxyapatite (HA) was incorporated into the agarose gels in situ in various ratios by a simple procedure consisting of precipitation, cooling, washing, and drying. The resulting gels were characterized regarding composition, porosity, mechanical properties, and biocompatibility. A pure phase of carbonated HA was identified in the scaffolds, which had pore sizes of up to several hundred micrometers. Mechanical testing revealed elastic moduli of up to 2.8 MPa for lyophilized composites. MTT testing on Lw35human mesenchymal stem cells (hMSCs) and osteosarcoma MG-63 cells proved the biocompatibility of the scaffolds. Furthermore, scaffolds were loaded with model drug compounds for guided hMSC differentiation. Different release kinetic models were evaluated for adenosine 5′-triphosphate (ATP) and suramin, and data showed a sustained release behavior over four days.

Pseuderanthemum carruthersii (Seem.) Guillaumin is a native tree in Vietnam. The water extract of the leaves from this tree gives a highly viscous product that has been used to heal wounds and treat inflammations. Our previous studies showed that the leaves of P. carruthersii have a high content of polysaccharides. In this study, the structure and influence of the neutral polysaccharide from Pseuderanthemum carruthersii (PCA1) on lipopolysaccharide (LPS)-stimulated RAW264.7 cells were investigated. The PCA1 isolated from P. carruthersii is a galactan-type polysaccharide, containing galactose (77.0%), 3-O-methyl galactose (20.0%), and arabinose (3.0%). Linkage analysis of PCA1 showed that both the 3-O-methyl galactose and galactose were 1,4-linked. The presence of 3-O-methyl galactose units as part of the polysaccharide is important and can be used as a chemotaxonomic marker. The molecular weight of the PCA1 was 170 kDa. A PCA1 concentration of 30−40 μg/mL strongly inhibited TNFα, IL-1β, and IL-6 inflammatory cytokine production, and reactive oxygen species (ROS) release. PCA1 had inhibitory activities on pro-inflammatory cytokine and ROS release in LPS-stimulated mouse macrophages in vitro through MAPK signaling.

In the past decade, ionic liquids (ILs) have received enormous interest as solvents for cellulose. They have been studied intensively for fractionation and biorefining of lignocellulosic biomass, for dissolution of the polysaccharide, for preparation of cellulosic fibers, and in particular as reaction media for the homogeneous preparation of highly engineered polysaccharide derivatives. ILs show great potential for application on a commercial scale regarding recyclability, high dissolution power, and their broad structural diversity. However, a critical analysis reveals that these promising features are combined with serious drawbacks that need to be addressed in order to utilize ILs for the efficient synthesis of cellulose derivatives. This review presents a comprehensive overview about chemical modification of cellulose in ILs. Difficulties encountered thereby are discussed critically and current as well as future developments in this field of polysaccharide research are outlined.

There is a sustained interest in developing solvents for physically dissolving cellulose, i.e., without covalent bond formation. The use of ionic liquids, ILs, has generated much interest because of their structural versatility that results in efficiency as cellulose solvents. Despite some limitations, imidazole-based ILs have received most of the scientific community’s attention. The objective of the present review is to show the advantages of using quaternary ammonium electrolytes, QAEs, including salts of super bases, as solvents for cellulose dissolution, shaping, and derivatization, and as a result, increase the interest in further investigation of these important solvents. QAEs share with ILs structural versatility; many are liquids at room temperature or are soluble in water and molecular solvents (MSs), in particular dimethyl sulfoxide. In this review we first give a historical background on the use of QAEs in cellulose chemistry, and then discuss the common, relatively simple strategies for their synthesis. We discuss the mechanism of cellulose dissolution by QAEs, neat or as solutions in MSs and water, with emphasis on the relevance to cellulose dissolution efficiency of the charge and structure of the cation and. We then discuss the use of cellulose solutions in these solvents for its derivatization under homogeneous and heterogeneous conditions. The products of interest are cellulose esters and ethers; our emphasis is on the role of solvent and possible side reactions. The final part is concerned with the use of cellulose dopes in these solvents for its shaping as fibers, a field with potential commercial application.

Cytocompatible polysaccharide-based functional scaffolds are potential extracellular matrix candidates for soft and hard tissue engineering. This paper describes a facile approach to design cytocompatible, non-toxic, and multifunctional chitosan-cellulose based hydrogel beads utilising polysaccharide dissolution in sodium hydroxide-urea-water solvent system and coagulation under three different acidic conditions, namely 2 M acetic acid, 2 M hydrochloric acid, and 2 M sulfuric acid. The effect of coagulating medium on the final chemical composition of the hydrogel beads is investigated by spectroscopic techniques (ATR–FTIR, Raman, NMR), and elemental analysis. The beads coagulated in 2 M acetic acid displayed an unchanged chitosan composition with free amino groups, while the beads coagulated in 2 M hydrochloric and sulfuric acid showed protonation of amino groups and ionic interaction with the counterions. The ultrastructural morphological study of lyophilized beads showed that increased chitosan content enhanced the porosity of the hydrogel beads. Furthermore, cytocompatibility evaluation of the hydrogel beads with human breast adenocarcinoma cells (soft tissue) showed that the beads coagulated in 2 M acetic acid are the most suitable for this type of cells in comparison to other coagulating systems. The acetic acid fabricated hydrogel beads also support osteoblast growth and adhesion over 192 h. Thus, in future, these hydrogel beads can be tested in the in vitro studies related to breast cancer and for bone regeneration.

The use of ionic liquids (ILs) in the field of cellulose chemistry opens up a broad variety of new opportunities. Besides the regeneration of the biopolymer to fibers, films, and beads, this new class of cellulose solvents is particularly useful for the homogeneous chemical modification of the polysaccharide. In this review, the potential of ILs as a reaction medium for the homogeneous cellulose functionalization is discussed. It is shown that numerous conversions proceed very efficiently and the ILs may be recycled. But it is also demonstrated that some side reactions have to be considered.

Tert-butyldimethylsilyl cellulose with a degree of substitution (DS) of up to 2 could be obtained by homogeneous conversion of the biopolymer with tert-butylchlorosilane in N,N-dimethyl aceteamide/LiCl in the presence of imidazole. The cellulose derivatives were characterized in detail by means of two-dimensional NMR spectroscopic techniques including subsequent derivatization of the original polymer by consecutive methylation-desilyation-acetylation. The very well resolved NMR spectra indicate that dependent on the reaction temperature 2,6-di-O-tert-butyldimethylsilyl moieties are the main repeating units. 3,6-di-O- and 6-mono-O functionalized repeating units were identified in very small amount if the reaction is carried out at room temperature. Additionally, 2,3,6-tri-O-silylated functions appear if reaction is carried out at temperature of 100°C. Thus, a novel path for regioselective protection of position 2 and 6 for cellulose was established.

Important cellulose solvents are described based on the systematization of derivatizing and non-derivatizing solvents. Advances and limitations of the homogeneous phase chemistry of the biopolymer will be discussed based on new results considering adequately own research work in the field.

A novel immobilization matrix for the entrapment of viable whole-cell Baeyer–Villiger monooxygenase was developed. Viable recombinant Escherichia coli cells overexpressing cyclohexanone monooxygenase were entrapped in polyelectrolyte complex beads prepared by a two-step reaction of oppositely-charged polymers including highly defined cellulose sulphate. Immobilized cells exhibited higher operational stability than free cells during 10 repeated cycles of Baeyer–Villiger biooxidations of rac-bicyclo[3.2.0]hept-2-en-6-one to the corresponding lactones (1R,5S)-3-oxabicyclo-[3.3.0]oct-6-en-3-one and (1S,5R)-2-oxabicyclo-[3.3.0]oct-6-en-3-one. The morphology of polyelectrolyte complex beads was characterised by environmental scanning electron microscopy; the spatial distribution of polymers in the beads and cell viability were examined using confocal laser scanning microscopy, and the texture was characterised by the mechanical resistance measurements.

The effect of cellulose-based polyelectrolytes on biomimetic calcium phosphate mineralization is described. Three cellulose derivatives, a polyanion, a polycation, and a polyzwitterion were used as additives. Scanning electron microscopy, X-ray diffraction, IR and Raman spectroscopy show that, depending on the composition of the starting solution, hydroxyapatite or brushite precipitates form. Infrared and Raman spectroscopy also show that significant amounts of nitrate ions are incorporated in the precipitates. Energy dispersive X-ray spectroscopy shows that the Ca/P ratio varies throughout the samples and resembles that of other bioinspired calcium phosphate hybrid materials. Elemental analysis shows that the carbon (i.e., polymer) contents reach 10% in some samples, clearly illustrating the formation of a true hybrid material. Overall, the data indicate that a higher polymer concentration in the reaction mixture favors the formation of polymer-enriched materials, while lower polymer concentrations or high precursor concentrations favor the formation of products that are closely related to the control samples precipitated in the absence of polymer. The results thus highlight the potential of (water-soluble) cellulose derivatives for the synthesis and design of bioinspired and bio-based hybrid materials.