Mechanical Energy Input Research Articles

Heat‐Engine and Entropy‐Production Analyses of the World Ocean

AbstractA heat‐engine analysis is performed in order to determine the ocean's Carnot efficiency, the maximum thermal energy (i.e., the Carnot work) available to drive the ocean circulation, and the ocean's irreversible entropy production. The analysis is based on a 36‐year monthly climatology of the surface heat flux; estimates of geothermal input, mechanical energy input, and heat storage; and a detailed treatment of freshwater fluxes. The ocean's Carnot efficiency is estimated to be 0.86%. The Carnot work is equal to 110 TW, which exceeds the mechanical energy input by the winds and tides. The net entropy flux from the ocean to its surroundings is found to be 0.617 TW/K, in good agreement with an independent estimate of the irreversible entropy production from viscous dissipation, thermal mixing, and haline mixing, demonstrating a balanced entropy budget of the ocean. Thermal mixing accounts for 56% of this entropy production, with most of the remaining production due to viscous dissipation and only small contributions from haline mixing and sea ice melting. Two thirds of the thermal entropy production is due to isopycnal mixing. The effect of thermal diffusion is to reduce the Carnot work significantly. The actual reduction is proportional to the amplitude of the (poorly known) eddy thermal diffusivity.

Scale-Up and In-line Monitoring During Continuous Melt Extrusion of an Amorphous Solid Dispersion

Chemical degradation of drug substances remains a major drawback of extrusion. Larger-scale extrusion equipment has advantages over smaller equipment due to deeper flight elements and added flexibility in terms of screw design, unit operations, and residence time. In a previous study, we extruded a meloxicam-copovidone amorphous solid dispersion (ASD) on a Nano-16 extruder and achieved 96.7% purity. The purpose of this study is to introduce a strategy for scaling the process to an extruder with dissimilar geometry and to investigate the impact on the purity of the ASD. The formulation previously optimized on the Nano-16, 10:90 meloxicam and copovidone, was used for scale-up. Our approach to scale-up to the ZSE-18, utilized specific mechanical energy input and degree of fill from the Nano-16. Vacuum was added to prevent hydrolysis of meloxicam. Downstream feeding and micronization of meloxicam were introduced to reduce the residence time. In-line monitoring of the solubilization of meloxicam was monitored with a UV probe positioned at the die. We were able to achieve the same purity of meloxicam with the Micro-18 as we achieved with Nano-16. When process conditions alone were not sufficient, meglumine was added to further stabilize meloxicam. In addition to the chemical stability advantage that meglumine provided, we also observed solubility enhancement which allowed for an increase in drug loading to 20% while maintaining 100% purity.

Pretreatment with lower feed moisture and lower extrusion temperatures aids in the increase in the fermentable sugar yields from fine-milled Douglas-fir

The impact of independent variables of extrusion on dependent variables of pre-milled Douglas-fir forest residuals was studied to enhance the enzymatic hydrolysis for production of fermentable sugar without catalysts. Co-rotating twin screw extruder was operated with three different feedstock moisture contents (30, 40, and 50%) at four different barrel temperatures (25, 50, 100, and 150 °C) as a pretreatment. The specific mechanical energy input ranged from 0.07 and 0.30 kWh/kg and had a very strong positive correlation with torque (r = 0.96, p < 0.01), glucose (r = 0.92, p < 0.01) and xylose/mannose yields with (r = 0.84, p < 0.01). Douglas-fir residuals extruded at lowest moisture content (30%) and temperature (25 °C) had the highest sugar yield, requiring the highest SME. Higher barrel temperature increased the median particle size and had lower glucose and xylose/mannose yields. Recrystallization and agglomeration were observed under higher temperature conditions.

Feasibility of Chemically Modified Cellulose Nanofiber Based Membrane as a Lithium Ion Battery Separator

One key concern in the lithium based energy storage device industry is its large environmental impacts, especially in terms of high energy input and components materials resulting in environmental pollutions during manufacturing and waste treatment. To overcome that of the conventional compartments of lithium ion batteries, there have been numerous attempts to replace their materials to such with lower environmental impact. Cellulose has been highlighted as a candidate because of its naturally abundance, low cost, bio-degradability. Besides, its thermal and chemical stability make it even more attractive as lithium ion battery materials. Cellulose fibrillated to individual nano-sized fibrils has been suggested as a useful material, which can also form nano-structures with high mechanical strength. Particularly, chemically modified cellulose has functionalized groups which can contribute to its excellent dispersibility in aqueous solutions and solvents. Therefore, chemically modified cellulose materials have advantages to be easily fabricated to light weight porous structures favorable for energy storage applications. TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) mediated oxidized cellulose (TOC) has sodium carboxylated groups converted from the primary hydroxyls at the C6 position. The functional groups give repulsion between fibrils, and facilitate dispersion of fibers. By consecutive mechanical disintegration, the pulp can be fabricated to nano-structured materials with a relatively low amount of mechanical energy input. Furthermore, negatively charged surface groups of the separators contribute to the transport of lithium ions, since a polyanionic surface can improve the transport rate of lithium cations. Furthermore, it is produced in large quantities in Nippon Paper Industries, Japan. Despite of its promising properties, its application for lithium ion batteries has been limited to a small quantity, such as the binders, coating materials, and the mechanical supports of gel-polymer electrolyte. We have found that TEMPO-oxidized cellulose based separator can be used for Li-ion batteries. From a water-based paper making process, fibrous cellulose treated by low mechanical/chemical energy input was fabricated to meso-porous structured membranes by simple filtration. The manufacturing process includes filtration and sequential solvent exchange with organic solvents to obtain desired structures of separators in terms of thickness, porosity, wettability of electrolyte and ionic conductivity. A battery cell composed of lithium Ni1/3Mn1/3CO1/3O2 (NMC) /Graphite electrodes and such separators showed excellent electrochemical performance. TEMPO-oxidized celluloses with different amounts of surface charge densities are produced and fabricated to be heat-resistant lithium ion battery separators. TEMPO-oxidized nanofibers with higher charge densities can facilitate the dispersion of cellulose and it contributes to an increase of mechanical strength. However, when fabricated to be a separator and applied for a battery cell, it showed unexpectedly poor electrochemical performance. We could assume that water remained in the cellulose structure limits the feasibility of high loading of wood based nanocellulose in the lithium ion batteries. Two types of water in TOC of concern are bound water adsorbed to the counter ions, and water in the cellulose amorphous structure which is difficult to remove via normal drying processes. Negatively charged cellulose can interact with higher amounts of water molecules on the cellulose structure while it goes through the water-based manufacturing process. Strong hydrogen bonds between water and cellulose stabilize the cellulose structures. Meanwhile, water can penetrate into amorphous regions of cellulose, whereas it cannot attack the crystalline regions. Therefore, it is inevitable to completely get rid of water from the wood based nanocellulose with low crystallinity and high surface area, prepared by aqueous based process, via normal drying process. Furthermore, since water remained can accelerate unwanted detrimental side reactions, resulting in the degradation of electrolytes and electrodes, it requires a delicate drying process. NMP (N-Methyl-2-pyrrolidone) was employed as the drying solvent for TOC nanofibers. The membrane immersed in NMP solvent and dried at 110 °C under vacuum showed enhanced electrochemical performance. NMP is an organic solvent widely used in industry because of its dispersibility. It is known as one of the cellulose-dissolving solvents, which can penetrate the cellulose structure, and interrupt the hydrogen bonding. We investigate the relationship between the electrochemical stability and the characteristics of separator materials. The results will give an overview for our future studies of the applications of cellulose materials produced by different chemical modification processes. Figure 1

Stellar population of the superbubble N 206 in the LMC

Context. Clusters or associations of early-type stars are often associated with a “superbubble” of hot gas. The formation of such superbubbles is caused by the feedback from massive stars. The complex N 206 in the Large Magellanic Cloud (LMC) exhibits a superbubble and a rich massive star population. Aims. Our goal is to perform quantitative spectral analyses of all massive stars associated with the N 206 superbubble in order to determine their stellar and wind parameters. We compare the superbubble energy budget to the stellar energy input and discuss the star formation history of the region. Methods. We observed the massive stars in the N 206 complex using the multi-object spectrograph FLAMES at ESO’s Very Large Telescope (VLT). Available ultra-violet (UV) spectra from archives are also used. The spectral analysis is performed with Potsdam Wolf–Rayet (PoWR) model atmospheres by reproducing the observations with the synthetic spectra. Results. We present the stellar and wind parameters of the OB stars and the two Wolf–Rayet (WR) binaries in the N 206 complex. Twelve percent of the sample show Oe/Be type emission lines, although most of them appear to rotate far below critical. We found eight runaway stars based on their radial velocity. The wind-momentum luminosity relation of our OB sample is consistent with the expectations. The Hertzsprung–Russell diagram (HRD) of the OB stars reveals a large age spread (1–30 Myr), suggesting different episodes of star formation in the complex. The youngest stars are concentrated in the inner part of the complex, while the older OB stars are scattered over outer regions. We derived the present day mass function for the entire N 206 complex as well as for the cluster NGC 2018. The total ionizing photon flux produced by all massive stars in the N 206 complex is Q0 ≈ 5 × 1050 s−1, and the mechanical luminosity of their stellar winds amounts to Lmec = 1.7 × 1038 erg s−1. Three very massive Of stars are found to dominate the feedback among 164 OB stars in the sample. The two WR winds alone release about as much mechanical luminosity as the whole OB star sample. The cumulative mechanical feedback from all massive stellar winds is comparable to the combined mechanical energy of the supernova explosions that likely occurred in the complex. Accounting also for the WR wind and supernovae, the mechanical input over the last five Myr is ≈ 2.3 × 1052 erg. Conclusions. The N206 complex in the LMC has undergone star formation episodes since more than 30 Myr ago. From the spectral analyses of its massive star population, we derive a current star formation rate of 2.2 × 10−3 M⊙ yr−1. From the combined input of mechanical energy from all stellar winds, only a minor fraction is emitted in the form of X-rays. The corresponding input accumulated over a long time also exceeds the current energy content of the complex by more than a factor of five. The morphology of the complex suggests a leakage of hot gas from the superbubble.

Facile Synthesis of Highly Hydrophobic Cellulose Nanoparticles through Post-Esterification Microfluidization

A post-esterification with a high degree of substitution (hDS) mechanical treatment (Pe(hDS)M) approach was used for the production of highly hydrophobic cellulose nanoparticles (CNPs). The process has the advantages of substantially reducing the mechanical energy input for the production of CNPs and avoiding CNP aggregation through drying or solvent exchange. A conventional esterification reaction was carried out using a mixture of acetic anhydride, acetic acid, and concentrated sulfuric acid, but at temperatures of 60–85 °C. The successful hDS esterification of bleached eucalyptus kraft pulp fibers was confirmed by a variety of techniques, such as Fourier transform infrared (FTIR), solid state 13C NMR, X-ray photoelectron spectroscopy (XPS), elemental analyses, and X-ray diffraction (XRD). The CNP morphology and size were examined by atomic force microscopy (AFM) as well as dynamic light scattering. The hydrophobicity of the PeM-CNP was confirmed by the redispersion of freeze-dried CNPs into organic solvents and water contact-angle measurements. Finally, the partial conversion of cellulose I to cellulose II through esterification improved PeM-CNP thermal stability.

Low moisture extrusion of pea protein and pea fibre fortified rice starch blends

Low moisture extrusion of rice starch fortified with pea protein and pea fibre was investigated as a potential approach to meet the increasing demand for novel food products with a balanced nutritional profile. Blends with four different protein contents (0, 10, 25 and 42% d.b.) and four different fibre contents (0, 8, 16 and 24%d.b.) were extruded. A full factorial design was applied for the blend composition, resulting in the investigation of 16 different blends. Screw speed (400 and 600 rpm), die temperature (130 and 150 °C) and moisture content (23 and 26%) were varied to identify their influence on the expansion behaviour and microstructure of the extrudates. Significant effects of both blend composition and extrusion conditions on the product characteristics were observed. The addition of protein and fibre resulted in increased specific mechanical energy inputs, bulk densities as well as air cell densities. At intermediate protein and fibre contents, expansion of the extrudate was statistically significant increased compared to the pure rice starch. However, the lowest expansion was observed for the highest protein and fibre content. Scanning electron microscopy, light microscopy and X-ray micro-computed tomography were used to identify microstructural changes caused by protein and fibre fortification. Microstructural analyses revealed that at the highest protein contents (42%), protein and starch were distributed in thin layers within the extrudate which is proposed to cause the decreased sectional expansion indices.

Carbon dioxide use in beneficiation of landfilled coal ash for hazardous waste immobilization

Landfilled coal fly ash and supplementary minerals were processed into a hydraulic cement binder via input of mechanical energy at ambient temperature in the presence of carbon dioxide (CO2) (considered as a gaseous raw material). An experimental program was conducted with the purpose of optimizing the raw materials formulation for achieving a desired balance of cement chemistry for CO2 capture, compressive strength and heavy metals immobilization qualities of the cement hydration products. The optimum formulation was found to complement high levels of CO2 capture with desired material properties offered by the hydration products. Insight into the structure of hydration products was gained by evaluating their chemical bond structure and thermogravimetry attributes.

High-recycled-content hydraulic cements of alternative chemistry for concrete production

ABSTRACTSustainable hydraulic cements based on alkali aluminosilicate chemistry were developed with market-limited wastes acting as the primary aluminosilicate precursors. Two sets of formulations were developed with waste brick or impounded coal ash used at relatively large volume as aluminosilicate precursors. Supplementary materials were used to produce raw materials of viable chemistry. Blends of raw materials were transformed into hydraulic cements by input of mechanical energy without resorting to elevated temperatures. The resultant hydraulic cements exhibited viable strength development characteristics. FTIR, SEM, EDS and NMR analyses were conducted in order to gain insight into the structure of the hydraulic cements and their hydration products. The results pointed at the prevalence of calcium aluminosilicate hydrates among the products of hydration which thoroughly bound the non-hydrated cores of cement particles.

Dynamics identification of a piezoelectric vibrational energy harvester by image analysis with a high speed camera

Abstract This study investigates dynamic responses of a nonlinear vibration energy harvester. The nonlinear mechanical resonator consists of a flexible beam moving like an inverted pendulum between amplitude limiters. It is coupled with a piezoelectric converter, and excited kinematically. Consequently, the mechanical energy input is converted into the electrical power output on the loading resistor included in an electric circuit attached to the piezoelectric electrodes. The curvature of beam mode shapes as well as deflection of the whole beam are examined using a high speed camera. The visual identification results are compared with the voltage output generated by the piezoelectric element for corresponding frequency sweeps and analyzed by the Hilbert transform.

Stellar population of the superbubble N 206 in the LMC

Context. Massive stars severely influence their environment by their strong ionizing radiation and by the momentum and kinetic energy input provided by their stellar winds and supernovae. Quantitative analyses of massive stars are required to understand how their feedback creates and shapes large scale structures of the interstellar medium. The giant H ii region N 206 in the Large Magellanic Cloud contains an OB association that powers a superbubble filled with hot X-ray emitting gas, serving as an ideal laboratory in this context. Aims. We aim to estimate stellar and wind parameters of all OB stars in N 206 by means of quantitative spectroscopic analyses. In this first paper, we focus on the nine Of-type stars located in this region. We determine their ionizing flux and wind mechanical energy. The analysis of nitrogen abundances in our sample probes rotational mixing. Methods. We obtained optical spectra with the multi-object spectrograph FLAMES at the ESO-VLT. When possible, the optical spectroscopy was complemented by UV spectra from the HST, IUE, and FUSE archives. Detailed spectral classifications are presented for our sample Of-type stars. For the quantitative spectroscopic analysis we used the Potsdam Wolf-Rayet model atmosphere code. We determined the physical parameters and nitrogen abundances of our sample stars by fitting synthetic spectra to the observations. Results. The stellar and wind parameters of nine Of-type stars, which are largely derived from spectral analysis are used to construct wind momentum − luminosity relationship. We find that our sample follows a relation close to the theoretical prediction, assuming clumped winds. The most massive star in the N 206 association is an Of supergiant that has a very high mass-loss rate. Two objects in our sample reveal composite spectra, showing that the Of primaries have companions of late O subtype. All stars in our sample have an evolutionary age of less than 4 million yr, with the O2-type star being the youngest. All these stars show a systematic discrepancy between evolutionary and spectroscopic masses. All stars in our sample are nitrogen enriched. Nitrogen enrichment shows a clear correlation with increasing projected rotational velocities. Conclusions. The mechanical energy input from the Of stars alone is comparable to the energy stored in the N 206 superbubble as measured from the observed X-ray and Hα emission.

Anisotropic mechanical responses of composites having water microchannels

The combination of extremely different materials could result in composites with unique properties, although their different properties make the combination challenging. If water-swellable phases are combined with water-insoluble rubbery phases, the resulting composites can act as water-swellable and mechanically durable rubbers. Herein, novel composites of hydrophilic poly(N-isopropylacrylamide) (PNIPAM) or poly(ethylene glycol) and hydrophobic polyurethane (PU) or poly(dimethylsiloxane) were prepared by directional melt crystallization and a subsequent infiltration process. When the composites were compressed parallel to their microchannel direction, much higher moduli were obtained, and their unique deflection and plateau regions existed due to irreversible deformations such as buckling. The moduli of water-swollen PU/PNIPAM were higher than those of porous PU. The hysteresis of cyclic compression was maximal in the cases of parallel compression with a low swelling ratio (SR), which could effectively absorb mechanical energy input. On the other hand, perpendicular compression with a high SR produced reversible mechanical behavior. These results demonstrate that the pore-filling properties of hydrogels by swelling enhance the mechanical properties of composites. We also found that the deswelling kinetics of composites were surprisingly fast. These unique properties of water-swellable composites could be advantageous for various applications in future industries.

Improving the stability of diesel emulsions with high pyrolysis bio-oil content by alcohol co-surfactants and high shear mixing strategies

Abstract Bio-oil from biomass pyrolysis is a clean, sustainable and renewable energy resource. In this study, the emulsification of pyrolysis bio-oil in diesel fuel using a commercial emulsifier (Atlox 4914) and three alcohols (methanol, ethanol and n-butanol) as co-surfactants is investigated, with emphasis on emulsion stability and minimum emulsifier usage. Results show that the higher the bio-oil content, the lower the relative content of surfactant required for successful emulsification. The addition of alcohol co-surfactants into the emulsions, especially for those with higher bio-oil content, significantly improves emulsion stability (methanol > ethanol > n-butanol). These findings are attributed to the differences in alcohol molecular structure, viscosity and density. In this study, the influence of mixing strategy on emulsion stability is also evaluated. The performance of a vortex mixer is compared with that of an inexpensive commercially available blender. The vortex mixer provided better short-term mixing due to a more uniform energy distribution but the off-the-shelf blender gives superior emulsion stability. The blender mixing method offers a simple, low-cost and high-speed mixing that can provide the necessary mechanical energy input for successful emulsification. Overall, the present study gives useful insights into the production of bio-oil in diesel emulsions with high bio-oil content.

Synthesis and characterization of alkali aluminosilicate hydraulic cement that meets standard requirements for general use

A sustainable hydraulic cement was developed based primarily upon the alkali aluminosilicate chemistry. This cement employed largely coal fly ash, granulated ground blast furnace slag and natural feldspar as sources of aluminosilicates, with small concentrations of calcium oxide, sodium hydroxide and sodium silicate used as sources of alkalis and soluble silica. In addition, sodium tetraborate was incorporated into the cement formulation for set retardation. The dry raw materials were transformed into a hydraulic cement via input of mechanical energy using a ball mill. Comprehensive experimental evaluation of the resultant hydraulic cement confirmed that it meets standard requirements for general use in concrete construction.

Choline chloride vs choline ionic liquids for starch thermoplasticization

Native starch containing 12% water was melt processed in presence of 23% of various plasticizers at 120°C, either by simple compression molding or by extrusion using a laboratory scale microcompounder. Glycerol, a typical starch plasticizer, was used as a reference and compared to three choline salts: raw choline chloride (which is a solid in dry state with a melting point above 300°C), and two ionic liquids synthesized from this precursor (choline acetate and choline lactate, liquids below 100°C). These ionic plasticizers were shown to allow a more efficient melting of native starch in both processes. The investigation of macromolecular structure changes during processing shows that this efficiency can be ascribed to a starch chain scission mechanism, resulting in lower specific mechanical energy input need for starch thermoplasticization compared to glycerol plasticized starch. Compared to the synthesized ionic liquids, raw commercial choline chloride leads to a good compromise between limited chain scission, and final water uptake and thermomechanical properties.

Synergistic effect of sodium hypochlorite and ultrasound bath in the decontamination of fresh arugulas

AbstractSanitization is a critical step for the reduction of microbial contaminants in fruits and vegetables in an effort to lessen the occurrence of foodborne diseases. The efficiency of different chemical compounds, either individually or combined with ultrasound treatment, in decontaminating fresh arugulas was evaluated here. The main physicochemical properties and the natural microbiota of arugulas were evaluated after sanitization for 5 min at 25 °C. The synergistic effect of ultrasound and sodium hypochlorite led to the best outcome. Ultrasound treatment improved the bactericidal effect of sodium hypochlorite (100 mg/L), leading to a reduction of 1.46 log cycles in relation to the non‐sanitized samples, whereas sodium hypochlorite itself provided a 0.85 log cycle reduction. This synergism is due to the ability of ultrasound‐induced cavitation to form oxidizing free radicals (e.g., ·OH and ·Cl), in addition to its mechanical energy input that facilitates the permeation of hypochlorous acid molecules into microbial cells. It is noteworthy that this mechanical action also favors the removal of microbial biofilms and cell disintegration. The residual chlorine content was lower than that recommended by the current legislation for public water supply. The combined action did not significantly alter the physicochemical and colorimetric properties of the arugulas. Therefore, this sanitization protocol denotes a promising alternative for the decontamination of fruits and vegetables in the food industry and in food processing facilities.Practical applicationsCurrently, there has been an increase in the demand for fresh food as well as an increase in the number of food outbreaks involving these products. In this context, to reduce microbial contamination, this research presents an alternative sanitization method that can be easily used in food processing units for decontamination of vegetables, increasing the microbiological safety of the final product to the consumer.

Theoretical prediction of temperature dependent shear modulus of bulk metallic glasses

A model of temperature dependent shear modulus and Young's modulus in bulk metallic glasses is established. The inherent relationship between the glass transition temperatures, the Debye temperature and shear modulus of bulk metallic glasses is revealed. The temperature dependent shear modulus can be predicted by our model without any fitting parameter. The model is presented based on a critical energy density criterion for plastic yielding which is derived from fundamental thermodynamics. This critical energy density consists of two parts: the heat added to the system and the input of mechanical energy, which are not completely equivalent. The agreement between theoretical results and experimental results is striking. And it is found that the temperature dependent Young's modulus could also be predicted pretty well by our model.

Processability and mechanical properties of bioplastics produced from decoloured bloodmeal

AbstractBloodmeal is a protein‐rich coproduct of the meat industry and can be converted into a thermoplastic. A solution of peracetic acid can be used to degrade colored compounds in bloodmeal, yielding a light yellow material. This causes an increase in β‐sheets in the protein's secondary structure, but the addition of sodium dodecyl sulfate (SDS) and triethylene glycol (TEG) reduced α‐helical and β‐sheet content, thereby increasing random coils. Without SDS, chains were less capable of folding into these structures, preventing sufficient intermolecular interactions and chain entanglement, leading to low specific mechanical energy input (SME) during extrusion, and poor consolidation. The whiteness of molded samples showed no correlation with SME during extrusion or the degree of consolidation after extrusion; however, they were observed to have a higher level of whiteness with increasing TEG content and should be considered as a secondary process not directly linked to extrusion. Increasing the amount of water during extrusion increased the Young's modulus (E) by facilitating formation of new interactions, while increasing TEG decreased E as a result of plasticization. The action of SDS on destabilizing electrostatic and hydrophobic interactions was beneficial to extrusion, although it had no further effect during injection molding. TEG had virtually no effect on tensile strength, although it was required for flow and facilitated the formation of strong interactions after water had been evaporated during conditioning.

Single Crystal, Luminescent Carbon Nitride Nanosheets Formed by Spontaneous Dissolution.

A primary method for the production of 2D nanosheets is liquid-phase delamination from their 3D layered bulk analogues. Most strategies currently achieve this objective by significant mechanical energy input or chemical modification but these processes are detrimental to the structure and properties of the resulting 2D nanomaterials. Bulk poly(triazine imide) (PTI)-based carbon nitrides are layered materials with a high degree of crystalline order. Here, we demonstrate that these semiconductors are spontaneously soluble in select polar aprotic solvents, that is, without any chemical or physical intervention. In contrast to more aggressive exfoliation strategies, this thermodynamically driven dissolution process perfectly maintains the crystallographic form of the starting material, yielding solutions of defect-free, hexagonal 2D nanosheets with a well-defined size distribution. This pristine nanosheet structure results in narrow, excitation-wavelength-independent photoluminescence emission spectra. Furthermore, by controlling the aggregation state of the nanosheets, we demonstrate that the emission wavelengths can be tuned from narrow UV to broad-band white. This has potential applicability to a range of optoelectronic devices.

Effect of low moisture extrusion on a pea protein isolate’s expansion, solubility, molecular weight distribution and secondary structure as determined by Fourier Transform Infrared Spectroscopy (FTIR)

To investigate the effect of low moisture extrusion cooking on the structural changes of protein and expansion properties, a pea protein isolate was processed in a twin screw extruder at varying screw speed (400-700 min−1), moisture content (26–35%) and barrel temperature (130–170 °C). An expanded protein isolate matrix was achieved for a specific mechanical energy input above 180 kJ/kg and product temperatures above 130 °C. The expanded protein network was presumably stabilized by increased protein aggregation, which most likely was formed by α-helices, β-sheet, non-covalently bonded β-turn or anti-parallel β-sheet structures as identified by FTIR. SDS-PAGE suggested, that neither the vicilin nor the convicilin fraction of the protein were altered, whereas legumin was either proteolysed or aggregated. Processing reduced the protein’s water solubility. This knowledge contributes to a deeper understanding of the structural changes in a pea protein isolate as caused by low moisture extrusion.