Increase In Molecular Weight Research Articles

Application of micro and nano modifying additives in road construction materials

The need for stronger and more sustainable road infrastructure has stimulated research into innovative materials, including micro- and nano-additives, to improve the performance of asphalt and bitumen. This paper aims to summarize the advances in the application of these additives with a focus on improving mechanical, thermal, and environmental properties. The study provides a detailed review of traditional micro-additives such as elastomers and resins, as well as advanced nanomaterials including nano silica, nano clay, and carbon nanoparticles. Methods include analyzing experimental data from recent studies on bitumen modification with biopolymeric materials such as polylactic acid (PLA), which show an increase in molecular weight, softening point, and ductility. The main results show that the use of nano additives improves the durability of the road surface, increases its resistance to cracking, and increases the service life of the material under different climatic conditions. For example, roads modified with nano silica showed a 20-30% improvement in tensile strength and a 15% reduction in deformation. In addition, PLA bitumen modification increased the softening point by 10°C and improved the overall elasticity by 25%. These results emphasize the potential of micro- and nano-additives to create more durable, environmentally friendly, high-performance road materials.

Heat diffusion coefficient study of polymers based on interpretable machine learning

Abstract. Polymers hold significant application value across various fields of modern society, with different application scenarios requiring specific thermal diffusivity coefficients. Finding polymer materials with targeted thermal diffusivities is crucial. However, due to the vast variety and complex structures of polymers, constructing a unified structured dataset for machine learning modeling is challenging. Although machine learning has shown great potential in materials science, it has rarely been applied to predict the heat diffusion coefficient of polymers. This paper constructs a dataset for predicting the thermal diffusion coefficient of polymers using a publicly available dataset by transforming the SMILES code of polymers into eight features with practical physical and chemical meanings. Using the Random Forest algorithm, training with 400 of these data and randomly selecting 200 of them for cross-validation, the accuracy of the test set reached 0.9. Additionally, through interpretability analysis, we found that the molecular weight of the polymer monomers, the TPSA (the polar surface area of the molecule), and the NRB (the number of rotatable bonds) are the main features affecting the polymer thermal diffusion coefficient. An increase in the TPSA and the NRB positively contributes to the thermal diffusivity, while an increase in molecular weight negatively contributes. Our study provides a new method for the prediction of polymer thermal diffusivity and creates a new paradigm for the study of polymer thermal diffusivity, promoting further development in this field.

Anaerobic Degradation of Aromatic and Aliphatic Biodegradable Plastics: Potential Mechanisms and Pathways.

Biodegradable plastics (BDPs) have been widely used as substitutes for traditional plastics, and their environmental fate is a subject of intense research interest. Compared with the aerobic degradation of BDPs, their biodegradability under anaerobic conditions in environmental engineering systems remains poorly understood. This study aimed to investigate the degradability of BDPs composed of poly(butylene adipate-co-terephthalate) (PBAT), poly(lactide acid) (PLA), and their blends, and explore the mechanism underlying their microbial degradation under conditions of anaerobic digestion (AD). The BDPs readily depolymerized under thermophilic conditions but were hydrolyzed at a slow rate under conditions of mesophilic AD. After 45 days of thermophilic AD, a decrease in the molecular weight and significant increase in the production of methane and carbon dioxide production were observed. Network and metagenomics analyses identified AD as reservoirs of plastic-degrading bacteria that produce multiple plastic-degrading enzymes. PETase was identified as the most abundant plastic-degrading enzyme. A potential pathway for the anaerobic biodegradation of BDPs was proposed herein. The polymers of high molecular weight were subjected to abiotic hydrolysis to form oligomers and monomers, enabling subsequent microbial hydrolysis and acetogenesis. Ultimately, complete degradation was achieved predominantly via the pathway involved in the conversion of acetic acid to methane. These findings provide novel insight into the mechanism underlying the anaerobic degradation of BDPs and the microbial resources crucial for the efficient degradation of BDPs.

Exploration of the Photoluminescence Behavior and Emission Mechanism of Thioester Polyacrylamide Tablets During the Gradual Increase of Molecular Weight.

To enhance the photoluminescence (PL) of unconventional luminescent compounds, particularly their persistent room temperature phosphorescence (p-RTP) performance, compressing the powder into tablets has been demonstrated as a viable approach. Nevertheless, the alterations in the emission capability of PL in compacted tablets have not been comprehensively investigated. In this study, four polyacrylamide (PAM) with controllable molecular weight (MW) are fabricated from powder to tablets, and their PL emission properties are thoroughly examined and compared with corresponding powders to elucidate the emission mechanism. As MW increases, both PL and p-RTP emissions of the tablets gradually intensify, exhibiting significant enhancement compared to the corresponding powder while retaining the characteristic blue shift. Through small angle X-ray scattering (SAXS), construction of molecular models for tablets, detailed analysis of molecular interactions, and theoretical calculations are conducted to reasonably explain these emission phenomena using clustering-triggered emission (CTE) and average packing density promoted emission (PDE) mechanisms. These findings not only advance the understanding of nonconventional luminogens' emission mechanisms but also offer new insights for preparing nonconventional luminescent polymers with controllable p-RTP emission performance.

Polymer Brushes Synthesized by the "Grafting-through" Approach: Characterization and Scaling Analysis.

In this study, a combined morphological and scaling analysis of brushes synthesized by the "grafting-through" method was performed, and the possibility of regulation of the thickness was revealed on an example of polyacrylamide brushes. The chemical composition of the surface in the proposed three-step approach was analyzed by photoelectron and infrared spectroscopy. It was shown that the thickness of the dried brush can be tuned in a controlled manner by varying the polymerization temperature. The scaling dependence of the thickness of the dried brushes d on the length of the polymer d ∼ Lv was obtained by comparing reflectometry and dynamic light scattering data. The value of the exponent v = 0.82 corresponds to a rather high grafting density, exceeding the density of mushroom-like (ν ∼ 1/3) brushes and approaching the value for stretched polymer brushes (ν ∼ 1). A 10-fold increase in the polymer molecular weight leads to a slight decrease in grafting density by a factor of 2, which suggests that the "grafting-through" approach allows obtaining brushes with a high grafting density independently of attached polymer chain length. Herein, the possibility of attachment of uniform polymer brush on large substrates with this approach was demonstrated, which means the scalability of the "grafting-through" technique. The considered approach opens up a simple way for surface modification with polymer nanolayers of controlled thickness.

Thermal Reactivity of Bio-Oil Produced from Catalytic Fast Pyrolysis of Biomass.

Catalytic fast pyrolysis (CFP) of biomass is a versatile thermochemical process for producing a biogenic oil that can be further upgraded to sustainable transportation fuels, chemicals, and materials. CFP oil exhibits reduced oxygen content and improved thermal stability compared to noncatalytic fast pyrolysis oil. However, some level of reactive oxygenates remain in CFP oils, and reactions between these species can result in molecular weight growth and increased viscosity, leading to the potential for challenges during transportation, storage, and downstream processing. Previous research has provided considerable insight into the reactivity of noncatalytic fast pyrolysis oils, but CFP oils have yet to be studied in a similar fashion. Consequently, the degree of catalytic upgrading that is necessary to effectively stabilize CFP oils has yet to be established, and little is known about the mechanistic details underlying the process. The current study addresses this knowledge gap by controlling the CFP reaction conditions to systematically vary the oxygen content of the resulting oil. Accelerated thermal reactivity studies were then performed, and the CFP oils were analyzed using gas chromatography-mass spectrometry (GC-MS), Fourier transform ion cyclotron mass spectrometry (FT-ICR MS), gel permeation chromatography (GPC), and viscometry to evaluate the impact of heating on their physical and chemical properties. The results revealed that short chain carbonyls, anhydrosugars, and lignin derivatives with conjugated vinyl groups likely play a role in the thermal reactivity of CFP oils. Additionally, experiments performed across a wide variety of feedstocks revealed relatively low thermal reactivity for CFP oils with oxygen contents of <20 wt %. However, above this threshold value, the thermal reactivity grew exponentially as a function of oxygen content, resulting in large increases in viscosity and molecular weight. These results serve to deepen the mechanistic understanding of CFP oil thermal reactivity and help inform the development of quality specifications for catalytic upgrading to effectively stabilize CFP oils.

A novel magnetorheological-polyethylene glycol shear thickening gel based on enhanced gel matrix

A novel magnetorheological-polyethylene glycol (PEG) shear thickening gel (MR-PSTG) with both shear thickening and magnetorheological effect is prepared based on polyethylene glycol shear thickening gel (PSTG) matrix possessing higher relative shear thickening effect (RSTE). Firstly, a new shear thickening mechanism is revealed through Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. Then, the orthogonal experiment is conducted to analyze the impact of factors on MR-PSTG and obtain the optimal factor combinations of the RSTE and relative magnetorheological effect (RMRE). Finally, the composite relative effect (CRE) is proposed to represent the comprehensive performance of MR-PSTG. Experiment results show that the RSTE increases with the increase of PEG molecular weight, and the maximum RSTE increases by 2.37 times. B atoms from the B-O-C structure in new molecular chains can share electrons with O atoms in the Si-O-Si structure to form B-O cross-linking bonds, which is responsible for the increase in RSTE. The orthogonal experiment indicates that the maximum RSTE and RMRE of MR-PSTG can reach 1024286% and 3839%, respectively. Results also show that the CIP mass fraction has the greatest impact on the RSTE, RMRE, and CRE of MR-PSTG, while the PEG mass has the smallest impact.

Calculated hydration free energies become less accurate with increases in molecular weight

In order for computer-aided drug design to fulfil its long held promise of delivering new medicines faster and cheaper, extensive development and validation work must be done first. This pertains particularly to molecular dynamics force fields where one important aspect–the hydration free energy (HFE) of small molecules–is often insufficiently analyzed. While most benchmarking studies report excellent accuracies of calculated hydration free energies–usually within 2 kcal/mol of experimental values–we find that deeper analysis reveals significant shortcomings. Herein, we report a dependence of HFE prediction errors on ligand molecular weight–the higher the weight, the bigger the prediction error and the higher the probability the calculated result is erroneous by a large amount. We show that in the drug-like molecular weight region, HFE predictions can easily be off by 5 kcal/mol or more. This is likely to be highly problematic in a drug discovery and development setting. We make our HFE results and molecular descriptors freely and fully available in order to encourage deeper analysis of future molecular dynamics results and facilitate development of the next generation of force fields.

Mild condition lignin modification enabled high-performance anticorrosive polyurethane coating

The diverse active hydroxyl groups of lignin pose challenges in the preparation of lignin-based polyurethane coatings with exceptional long-term anticorrosive properties. Here, the dense and defect-free lignin-based polyurethane coating with a thickness of 25 ± 5 μm was successfully synthesized using a mild hydroxypropyl lignin modification approach, exhibiting outstanding barrier properties (|Z| > 109 Ω cm2) and long-term anti-corrosion performance exceeding 120 d. Under ambient conditions (i.e., 25 °C and atmospheric pressure), propylene oxide was directly blended with the alkali solution of lignin to effectively convert phenolic hydroxyl groups into more reactive aliphatic hydroxyl groups, while also minimizing the significant increase in molecular weight caused by lignin condensation. As a result, the high crosslinking density of lignin polyurethane coatings effectively prevented the penetration of corrosive media and enhanced the long-term corrosion resistance of the coatings. Overall, the results demonstrate that a mild hydroxypropyl modification process is an effective and facile strategy to prepare highly reactive lignin-based polyols, which is crucial for the development of high-performance bio-based polyurethane anticorrosive coatings.

Efficient production of pullulan by Aureobasidium pullulans using a multi-objective optimization strategy with orthogonal experimental design coupling artificial neural network and genetic algorithm

Efficient pullulan production has long been a central research focus. This study used maltodextrin as the carbon source for pullulan production by Aureobasidium pullulans fermentation. A hybrid optimization approach, integrating orthogonal experimental design (OED), backpropagation artificial neural network (BP-ANN), and elite strategy non-dominated sequential genetic algorithm-II (NSGA-II), was developed. Range analysis based on OED revealed that MgSO4·7H2O significantly affects production but less impacts molecular weight, while pH notably influences molecular weight with a lesser effect on production, underscoring the need for multi-objective optimization. The BP-ANN model showed strong predictive capabilities, with goodness-of-fit values of 0.984 and 0.980 for production and molecular weight, respectively. Using this model as the fitness function for the optimization algorithm enhanced efficiency. Taking cost factors into account, the BP-ANN-NSGA-II algorithm identified the optimal fermentation medium conditions, resulting in a 6.89 % increase in production, a 368.97 % increase in molecular weight, and a 42.49 % reduction in cost. The maximum comprehensive optimization efficiency is 63.73 %, and the multi-objective optimization is better than the single objective optimization. This method significantly guides the improvement of pullulan fermentation optimization efficiency.

Divergent response of Chernozem organic matter towards short-term water stress in Poa pratensis L. rhizosphere and bulk soil in pot experiments: A spectroscopic study

Understanding and controlling rhizospheric processes under abiotic stress is one of the key challenges in addressing food security amid the climate crisis. In this work, the impact of short-term drought and overwatering on soil organic matter (SOM) of Haplic Chernozem in the rhizosphere of Poa pratensis L. and in bulk soil was investigated. The vegetation experiment was conducted in a climatic chamber at soil moisture levels of 35, 80, and 200 % of the field capacity. UV-Vis and spectrofluorometry were used to describe the water-extractable organic matter (WEOM) characteristics and fluorofores signature, and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to describe functional group composition of SOM. Composition and properties of SOM and WEOM of Chernozem significantly change after exposure to short-term water stress. Drought does not affect the composition of rhizosphere SOM except increasing the proportion of polysaccharides, but leads to the decrease in aromaticity and increase in molecular weight of humic-like components of rhizosphere WEOM. These findings reflect Poa adaptation to water deficiency and microbial activity suppression which results in accumulation of SOM intermediate decomposition products. On the contrary, bulk WEOM wasn't affected by drought but SOM became enriched with aromatic and oxidised components. Overwatering leads to equalisation of bulk and rhizospheric SOM composition due to a decrease in the proportion of aromatic and carboxylic components of bulk SOM and the accumulation of microbial products in both bulk and rhizospheric SOM. In general, rhizospheric WEOM undergoes relatively significant changes relative to the optimum water regime under moisture deficit, and bulk WEOM — under overwatering. The findings illustrate the involvement of the both WEOM and SOM in maintaining resilience of the soil-plant system as well as the difference in watering conditions impact on SOM in rhizosphere and bulk soil. SOM spectral data can be used for assessing the state of soil systems, such as changes in microbial activity and adaptation of the soil-plant system to abiotic stress. Our findings also illustrate the differences in the organic matter transformation of the Poa pratensis rhizosphere and the bulk Chernozem depending on environmental factors.

Modification mechanism of green polyurethane modified asphalt prepared by in-situ polymerization

In order to investigate the modification mechanism of green polyurethane (PU) modified asphalt prepared by in-situ polymerization, PU was separated from PU modified asphalt (PUMA) and the molecular fragmentation information of synthesized PU and separated PU was characterized by pyrolysis-gas chromatography-mass spectrometry. The binding forms of the asphalt molecules to the PU were deduced, and the deduced structures were validated by infrared spectroscopy, nuclear magnetic hydrogen spectroscopy, gel chromatography, elemental analysis, and molecular dynamics simulation. The results showed that compared to synthetic PU, the PU molecular fragments separated from modified asphalt additionally contained active asphalt components. Meanwhile, infrared and hydrogen spectra verified that the active components in the asphalt can chemically with -NCO in the PU prepolymer. The extension of curing time led to more combinations of asphalt molecules and PU prepolymers, which were manifested in the increases of the element contents of C, O, and S and the increase of molecular weight of PU separated from PUMA. The chain extender could not be completely reacted during the preparation and curing of PUMA and after curing for 6 months, the binding rate of PU prepolymer and chain extender was 24.80 %. PU prepolymer can react with the moisture in the air to generate amine group, and further generates urea group during the preparation and curing of PUMA. This work serves as a reference for the design and preparation of PUMA by in-situ polymerization.

Electrosprayed Chitosan Nanospheres-Based Films: Evaluating the Effect of Molecular Weight on Physicochemical Properties

This study explores the effect of chitosan molecular weight on the formation of chitosan-based films by electrospraying process. The oxidative pathway was employed in chitosan with 220.1 kDa to obtain samples with 124.5 and 52.7 kDa. Both samples of depolymerized chitosan resulted in spheres within electrosprayed chitosan-based films due to a higher deacetylation degree (~85%). The increase in molecular weight (52.7 to 124.5 kDa) resulted in nanospheres (562 nm) within electrosprayed chitosan-based films, enhancing the surface area-to-volume ratio of the material. The electrospraying process maintained the structural integrity and thermal stability of all chitosan-based films while reducing their crystallinity. These findings highlight the impact of chitosan properties, particularly molecular weight, on the physicochemical characteristics of electrosprayed chitosan-based films. For instance, this work provides insights for the application of electrosprayed chitosan-based films in various fields.

Relationship between the interfacial properties of lactoferrin-(−)-epigallocatechin-3-gallate covalent complex and the macroscopic properties of emulsions

This study explored the relationship between the interfacial behavior of lactoferrin-(−)-epigallocatechin-3-gallate covalent complex (LF-EGCG) and the stability of high internal phase Pickering emulsions (HIPPEs). The formation of covalent bond between lactoferrin and polyphenol was verified by the increase in molecular weight. In LF-EGCG group, the surface hydrophobicity, interfacial pressure, and adsorption rate were decreased, while the molecular flexibility, interfacial film viscoelasticity, and interfacial protein content were increased. Meanwhile, LF-EGCG HIPPE possessed reduced droplet size, increased ζ-potential and stability. Rheology showed the viscoelasticity, structural recovery and gel strength of LF-EGCG HIPPE were improved, giving HIPPE inks better 3D printing integrity and clarity. Moreover, the free fatty acids (FFA) release of LF-EGCG HIPPE (62.6%) was higher than that of the oil group (50.1%). Therefore, covalent treatment effectively improved the interfacial properties of protein particles and the stability of HIPPEs. The macroscopic properties of HIPPEs were positively regulated by the interfacial properties of protein particles. The result suggested that the stability of emulsions can be improved by regulating the interfacial properties of particles.

The influence of olive kernel ash obtained from canning factory as a bitumen modifier

Today, the construction sector experiences significant pressure to use green and sustainable materials. In this framework, using biological components derived from agricultural products is the most interesting topic for the stability of asphalt pavement construction materials. Furthermore, the escalation in demand for transportation infrastructure has resulted in a rapid surge in the volume of traffic and premature degradation of asphalt pavements. The primary objective of this study is to assess the efficacy of olive kernel ash (OKA) obtained from olive canning factories in modifying the characteristics of asphalt. The investigation of this function has not been explored in prior research. To this end, a comprehensive analysis of morphological, Thermogravimetric, chemical, and phase separation was conducted, in addition to physical and rheological testing, over three distinct temperature ranges: high, intermediate, and low. The results showed that OKA is thermally stable and has a slow decomposition. Also, using OKA, compared to most biomass employed in bitumen, exhibits a satisfactory amount of phase separation. Despite the enhanced shear strength, the modified samples incorporating OKA do not encounter any operational challenges regarding transportation and pumping. The findings from the rheological experiments indicate that incorporating 20 % OKA in bitumen can increase the shear modulus up to 71 % and recovery percentage up to 20 %. Therefore, it significantly enhances the resistance to permanent deformation under high temperatures. The increase in molecular weight and asphaltene phase creates a resistant binder against high temperatures. Meanwhile, the fatigue life of modified samples containing 20 % OKA decreased to 59 %. However, applying the highest shear stress to the sample containing OKA experiences demonstrates its ability to resist this stress for longer. Also, it was found that regulating the OKA dosage in bitumen can maintain its acceptable resistance level to cracking at low temperatures. This phenomenon is due to the positive effect of OKA on the viscoelastic characteristics of bitumen. Based on our assessments, it has been observed that incorporating OKA up to 20 % in bitumen consistently enhances its performance capabilities at high temperatures. Nevertheless, while using this modified bitumen in cold regions, limiting its utilization to a maximum of 5 % is advisable.

Role of the Soft and Hard Segments Structure in Modifying the Performance of Acrylic Adhesives Modified by Polyurethane Macromonomers.

Acrylic pressure sensitive adhesives, modified by polyurethane (PU), achieve selective optimization through the designability of polyurethanes. In this paper, PU macromonomers were prepared by a two-step synthesis method, using polypropylene glycol or polyethylene glycol with different molecular weights as soft segments and different types of diisocyanates: isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethylmethane diisocyanate (HMDI), 2,4-toluene diisocyanate (TDI), and 4,4'-diphenylmethane diisocyanate (MDI) and chain extenders as hard segments. After being terminated by capping agents, a series of PU macromonomers of different molecular weights and structures were obtained and used to modify the acrylic base adhesives. Compared to unmodified adhesives, acrylic adhesives modified by PU macromonomers have improved adhesion performances and heat resistance and show an increasing trend with the increase of molecular weight of diols. Diols with a molecular weight of 600 have the best effect. Diisocyanates containing benzene rings can better improve the thermal performance of adhesives, where P MDI containing a biphenyl ring is the best, while aliphatic isocyanate groups have a greater improvement in adhesion performance, and the adhesion performance of P HDI with a long carbon chain is the best.

Effect of macromolecular sodium polyacrylate on the molecular structure and properties of polyvinyl butyral synthesized deep eutectic solvent

AbstractSodium polyacrylate (PAAS), a macromolecule surfactant, was employed in the synthesis of polyvinyl butyral (PVB) using a deep eutectic solvent (DES) as the catalyst. Contrasting with traditional low molecular weight surfactants, scanning electron microscopy (SEM) analysis has confirmed that PAAS enhanced the uniformity of PVB granules while minimizing PAAS residuals, facilitating the production of films with superior transparency and resistance to yellowing. Investigations into the effects of varying molecular weights, dosages of PAAS, and aging times on the properties of PVB revealed that an increase in PAAS molecular weight correspondingly raised the acetal degree (AD) of PVB without affecting the molecular weight of PVB itself. Furthermore, yhe dosage of PAAS significantly impacted the properties of PVB, whereas aging time exhibits minimal influence on the AD of PVB. 1H‐NMR analysis indicated that the structural stability of PVB is due to the dominance of meso acetal isomers, which improved its mechanical properties when synthesized with PAAS3 (molecular weight 60,000 g/mol), containing 91.5% hexamethylene cycloacetal. Notably, compared to PVB synthesized using sodium dodecyl sulphate (SDS), PVB synthesized with PAAS3 exhibits superior mechanical properties, with significantly improved tensile strength and elongation. This phenomenon is further elucidated by SEM images. A comparison between the optimized self‐made PVB and commercial PVB shows that the self‐made PVB performs better, highlighting the critical role of macromolecular PAAS in enhancing the structure and mechanical properties of PVB.

Dihydropyridopyrazine Functionalized Xanthene: Generating Stable NIR Dyes with Small-Molecular Weight by Enhanced Charge Separation.

Near-infrared region (NIR; 650-1700 nm) dyes offer many advantages over traditional dyes with absorption and emission in the visible region. However, developing new NIR dyes, especially organic dyes with long wavelengths, small molecular weight, and excellent stability and biocompatibility, is still quite challenging. Herein, we present a general method to enhance the absorption and emission wavelengths of traditional fluorophores by simply appending a charge separation structure, dihydropyridopyrazine. These novel NIR dyes not only exhibited greatly redshifted wavelengths compared to their parent dyes, but also displayed a small molecular weight increase together with retained stability and biocompatibility. Specifically, dye NIR-OX, a dihydropyridopyra-zine derivative of oxazine with a molecular mass of 386.2 Da, exhibited an absorption at 822 nm and an emission extending to 1200 nm, making it one of the smallest molecular-weight NIR-II emitting dyes. Thanks to its rapid metabolism and long wave-length, NIR-OX enabled high-contrast bioimaging and assessment of cholestatic liver injury in vivo and also facilitated the evalua-tion of the efficacy of liver protection medicines against cholestatic liver injury.

Dihydropyridopyrazine Functionalized Xanthene: Generating Stable NIR Dyes with Small‐Molecular Weight by Enhanced Charge Separation

Near‐infrared region (NIR; 650–1700 nm) dyes offer many advantages over traditional dyes with absorption and emission in the visible region. However, developing new NIR dyes, especially organic dyes with long wavelengths, small molecular weight, and excellent stability and biocompatibility, is still quite challenging. Herein, we present a general method to enhance the absorption and emission wavelengths of traditional fluorophores by simply appending a charge separation structure, dihydropyridopyrazine. These novel NIR dyes not only exhibited greatly redshifted wavelengths compared to their parent dyes, but also displayed a small molecular weight increase together with retained stability and biocompatibility. Specifically, dye NIR‐OX, a dihydropyridopyra‐zine derivative of oxazine with a molecular mass of 386.2 Da, exhibited an absorption at 822 nm and an emission extending to 1200 nm, making it one of the smallest molecular‐weight NIR‐II emitting dyes. Thanks to its rapid metabolism and long wave‐length, NIR‐OX enabled high‐contrast bioimaging and assessment of cholestatic liver injury in vivo and also facilitated the evalua‐tion of the efficacy of liver protection medicines against cholestatic liver injury.

Effect of Changing the Concentration of Zinc Oxide Nanoparticles on the Viscosity of the Polyacrylamide / Polyethylene Glycol Solutions

In this work, Polyacrylamide/ Polyethylene glycol solutions of different molecular weights for Polyethylene glycol and different concentrations (17, 29, 38, 45, and 57 %) of ZnO nanoparticles were prepared by dissolving 0.5g of Polyethylene glycol in 20mL Polyacrylamide, then adding different concentrations of ZnO nanoparticles. Relative viscosity values are calculated by using the efflux time of the solutions, the viscosities(relative viscosity (ƞr), specific viscosity (ƞsp), reduced viscosity (ƞred) and inherent viscosity (ƞint) were calculated for all solutions, where measurements indicated an increase in these properties with increased concentration of ZnO nanoparticles and increased molecular weight of Polyethylene glycol. Viscosity is a significant parameter during the electrospinning process, and if the molecular weight increases, the viscosity of the solutions increases, making subsequent synthesis and purification more difficult. the constants KH and KK were calculated from the slopes of the viscosity values related to the Huggins and Kramer equations. These results can be used in many applications and scientific studies.