Bulk Processes Research Articles

Adsorptive separation using self-assembly on graphite: from nanoscale to bulk processes.

Adsorptive separation is a promising lower-energy alternative for traditional industrial separation processes. While carbon-based materials have a long history in adsorptive removal of organic contaminants from solution or gas mixtures, separation using an adsorption/desorption protocol is rarely considered. The main drawbacks are the limited control in bulk adsorption experiments, as often all organic molecules are adsorbed, and lack of desorption methods to retrieve the adsorbed molecules. Using high-resolution on-surface characterization with scanning tunneling microscopy (STM), an increased understanding of the on-surface adsorption behavior under different conditions was obtained. The insight obtained from the nanoscale experiments was used to develop a highly selective separation method using adsorption and desorption on graphite, which was tested for the separation of quinonoid zwitterions. These experiments on adsorptive separation using self-assembly on graphite show its potential and demonstrate the advantage of combining surface characterization techniques with bulk experiments to exploit different possible applications of carbon-based materials.

FlexBRDF: A Flexible BRDF Correction for Grouped Processing of Airborne Imaging Spectroscopy Flightlines.

Bidirectional reflectance distribution function (BRDF) effects are a persistent issue for the analysis of vegetation in airborne imaging spectroscopy data, especially when mosaicking results from adjacent flightlines. With the advent of large airborne imaging efforts from NASA and the U.S. National Ecological Observatory Network (NEON), there is increasing need for methods that are flexible and automatable across images with diverse land cover. Flexible bidirectional reflectance distribution function (FlexBRDF) is built upon the widely used kernel method, with additional features including stratified random sampling across flightline groups, dynamic land cover stratification by normalized difference vegetation index (NDVI), interpolation of correction coefficients across NDVI bins, and the use of a reference solar zenith angle. We demonstrate FlexBRDF using nine long (150–400 km) airborne visible/infrared imaging spectrometer (AVIRIS)‐Classic flightlines collected on 22 May 2013 over Southern California, where diverse land cover and a wide range of solar illumination yield significant BRDF effects. We further test the approach on additional AVIRIS‐Classic data from California, AVIRIS‐Next Generation data from the Arctic and India, and NEON imagery from Wisconsin. Comparison of overlapping areas of flightlines show that models built from multiple flightlines performed better than those built for single images (root mean square error improved up to 2.3% and mean absolute deviation 2.5%). Standardization to a common solar zenith angle among a flightline group improved performance, and interpolation across bins minimized between‐bin boundaries. While BRDF corrections for individual sites suffice for local studies, FlexBRDF is an open source option that is compatible with bulk processing of large airborne data sets covering diverse land cover needed for calibration/validation of forthcoming spaceborne imaging spectroscopy missions.

The Influence of Storage Temperature on the Weight of Golden Delicious Apples

The great majority of customers choose nutritious, fresh fruit with a distinct color for human ingestion. The Golden Delicious apple is a popular yellow-colored, delicate, sweetish, somewhat acidic, crisp-fleshed, juicy, fragrant, and aromatic apple. Apples, like other fruits, are stressed throughout their development and growth in the field, as well as during harvest and the postharvest environment (processing, storage, transportation). The refrigerated system enables bulk processing of food goods from harvest to market, guaranteeing that freshness and integrity are preserved for a prolonged time through precise temperature and humidity regulation. This study looked at the effects of three months of storage on the weight loss of Golden Delicious apples, both under refrigerated settings at 5±0.5°C and 82% relative humidity and in controlled ambient conditions at 25±0.5°C relative humidity and 60% relative humidity. The results showed that the weight loss in the two groups of apples was different. Apples held in cold storage lost 3.31g to 4.59g of weight; meanwhile, apples stored at room temperature lost 23.29g to 31.76g of weight.

Enzyme-photo-coupled catalysis in gas-sprayed microdroplets.

Enzyme-photo-coupled catalysis produces fine chemicals by combining the high selectivity of an enzyme with the green energy input of sunlight. Operating a large-scale system, however, remains challenging because of the significant loss of enzyme activity caused by continuous illumination and the difficulty in utilizing solar energy with high efficiency at large scale. We present a large-scale enzyme-photo-coupled catalysis system based on gas-sprayed microdroplets. By this means, we demonstrate a 43.6–71.5 times improvement of solar energy utilization over that using a traditional bulk processing system. Owing to the improved enzyme activity in microdroplets, we show that chiral alcohols can be produced with up to a 2.2-fold increase in the reaction rate and a 5.6-fold increase in final product concentration.

Lithium transport and intermetallic generation in Li–Bi liquid metal batteries

Liquid metal batteries (LMBs) are a potential electrochemical energy storage technology. However, solid intermetallics could be generated during operation, which hinders the transport of the negative metal in the positive region. In this research, the operating processes of an existing Li||Bi LMB are simulated using a 2-D axisymmetric model considering intermetallic generation, mass transport and electrochemical reactions. The model simulates the lithium-ion transport and electrochemical reaction processes in the positive bulk with a calculation method for the intermetallic distribution. The battery performance evolution based on the positive composition development is investigated, and the losses caused by the different processes at different rates are compared. The large electrolyte ohm loss limits the operation of LMBs at a high rate, and the electrochemical performance is optimized by reducing the electrolyte thickness. However, a thin electrolyte leads to a risk of short circuits caused by predictable positive volume expansion and unpredictable contact. The model can be used to determine the minimum electrolyte thickness to prevent the LMBs from a positive volume expansion-induced short circuit. A plasma-sprayed MgO coating is suggested to be deposited on the bottom of the nickel foam to prevent unpredictable contact.

Microfluidics-based production of chitosan-gellan nanocomplexes encapsulating caffeine

Electrostatic complexes produced by interactions between polysaccharides have promising applications in the medical, pharmaceutical and food fields. In this light, for the development of such particles, microfluidics emerges as a promising technique in which processes occur at a strict laminar flow regime, allowing diffusion-dominated transport and particle formation in highly-controlled conditions. As a proof of concept, we compared bulk versus microfluidic (different devices simulating a range of residence times) processes for the production of electrostatic complexes of gellan with either chitosan (molecular weight ∼ 28 kDa) or hydrolyzed chitosan (molecular weight ∼ 3 kDa). Regardless of the process, polysaccharide solutions (pH 4.5) were mixed in pre-defined concentrations (polysaccharide ratios) to form electrostatic complexes that were used to encapsulate caffeine. These complexes were characterized by zeta potential measurements and particle size distribution. Overall, microfluidics produced complexes with improved characteristics such as lower polydispersity index (PDI ∼ 0.1) and mean size (∼200 nm) when compared to the conventional bulk process (PDI ∼ 0.3 and mean size ∼ 400 nm). Moreover, hydrolyzed chitosan (HC) contributed to an even smaller size and PDI value of the complexes. Such outcome is associated with the lower molecular weight and higher solubility of HC when comparing to conventional chitosan, which in turn improves electrostatic complexation. Caffeine could also be encapsulated in all complexes, but the highest encapsulation efficiency was achieved using microfluidics (70%) and with the geometry that provided a longer residence time. Therefore, we were able to demonstrate that microfluidics is clearly an effective strategy for generating electrostatic complexes with improved properties. Ultimately, this technique demonstrated a high potential for the production of vehicles of bioactive compounds.

Heterogeneous oxidation of powder and individual carbon nanoparticles catalyzed by ceria nanoparticles

To comply with stricter regulations on particulate emissions, ceria based catalyst has been researched in developing diesel particulate filters. Here chemical reaction parameters are determined experimentally for CeO2-nanoparticle catalyzed soot oxidation for two representative environments: a bulk process with a catalyst/carbon mixture and individual carbon-nanoparticles attached to CeO2. The first task was carried out in simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) experiments, while the second was performed with in-situ environmental scanning transmission electron microscopy (ESTEM). The TGA/DSC results suggested the role of gas diffusion through the porous sample was significant and slowed down the reaction rate. The ESTEM videos affirmed the catalyzed reaction resulted in a higher oxidation rate at the contact area between CeO2 and carbon, which caused the movement of carbon nanoparticles towards CeO2. Measured reaction kinetics data were compared to the Darcy’s model and their discrepancies were elaborated.

Application of Tamm Plasmon Polaritons and Cavity Modes for Biosensing in the Combined Spectroscopic Ellipsometry and Quartz Crystal Microbalance Method.

Low-cost 1D plasmonic photonic structures supporting Tamm plasmon polaritons and cavity modes were employed for optical signal enhancement, modifying the commercially available quartz crystal microbalance with dissipation (QCM-D) sensor chip in a combinatorial spectroscopic ellipsometry and quartz microbalance method. The Tamm plasmon optical state and cavity mode (CM) for the modified mQCM-D sample obtained sensitivity of ellipsometric parameters to RIU of ΨTPP = 126.78 RIU−1 and ΔTPP = 325 RIU−1, and ΨCM = 264 RIU−1 and ΔCM = 645 RIU−1, respectively. This study shows that Tamm plasmon and cavity modes exhibit about 23 and 49 times better performance of ellipsometric parameters, respectively, for refractive index sensing than standard spectroscopic ellipsometry on a QCM-D sensor chip. It should be noted that for the optical biosensing signal readout, the sensitivity of Tamm plasmon polaritons and cavity modes are comparable with and higher than the standard QCM-D sensor chip. The different origin of Tamm plasmon polaritons (TPP) and cavity mode (CM) provides further advances and can determine whether the surface (TPP) or bulk process (CM) is dominating. The dispersion relation feature of TPP, namely the direct excitation without an additional coupler, allows the possibility to enhance the optical signal on the sensing surface. To the best of our knowledge, this is the first study and application of the TPP and CM in the combinatorial SE-QCM-D method for the enhanced readout of ellipsometric parameters.

Synthesis of Biobased and Hybrid Polyurethane Xerogels from Bacterial Polyester for Potential Biomedical Applications.

Organic–inorganic xerogel networks were synthesized from bacterial poly (3-hydroxybutyrate) (PHB) for potential biomedical applications. Since silane-based networks usually demonstrate increased biocompatibility and mechanical properties, siloxane groups have been added onto polyurethane (PU) architectures. In this work, a diol oligomer (oligoPHB-diol) was first prepared from bacterial poly(3-hydroxybutyrate) (PHB) with an environmentally friendly method. Then, hexamethylene diisocyanate or biobased dimeryl diisocyanate was used as diisocyanate to react with the short oligoPHB-diol for the synthesis of different NCO-terminated PU systems in a bulk process and without catalyst. Various PU systems containing increasing NCO/OH molar ratios were prepared. Siloxane precursors were then obtained after reaction of the NCO-terminated PUs with (3-aminopropyl)triethoxysilane, resulting in silane-terminated polymers. These structures were confirmed by different analytical techniques. Finally, four series of xerogels were prepared via a sol–gel process from the siloxane precursors, and their properties were evaluated depending on varying parameters such as the inorganic network crosslinking density. The final xerogels exhibited adequate properties in connection with biomedical applications such as a high in vitro degradation up to 15 wt% after 12 weeks.

30 Years of Macromolecular Theory and Simulations

30 Years of <i>Macromolecular Theory and Simulations</i>

A review on processing and characterization of bulk functionally graded polymer materials

Functionally Graded Polymer Materials (FGPMs) have received much interest in replacing conventional composites due to their multifunctional properties and microstructural variation of desired materials to enhance performance for specific applications. In addition, these are recognized for their build with varying compositions in a smooth gradient throughout its structure and the possibility of stress reduction due to the absence of sharp interfaces compared to conventional homogenous structures. Recently, the contribution of FGPMs with multiple material combinations for various applications in materials science and engineering has attracted many researchers, and its awareness has led to significant advancements in processing techniques. This study reviews recent developments in processing techniques and conventional attempts made to prepare bulk FGPMs. Further, the mechanical, thermal, electrical, and other characterizations of prepared FGPM structures and their related properties are addressed. Also, their applications in exciting fields include dielectrics, radiation shielding, vibration damping, and bio-medical fields, are highlighted.

Effect of confinement on the dynamics of 1-propanol and other monohydroxy alcohols.

We report the effect of confinement on the dynamics of three monohydroxy alcohols (1-propanol, 2-ethyl-1-hexanol, and 4-methyl-3-heptanol) differing in their chemical structure and, consequently, in the dielectric strength of the "Debye" process. Density functional theory calculations in bulk 1-propanol identified both linear and ring-like associations composed of up to five repeat units. The simulation results revealed that the ring structures, with a low dipole moment (∼2D), are energetically preferred over the linear assemblies with a dipole moment of 2.18D per repeat unit. Under confinement in nanoporous alumina (in templates with pore diameters ranging from 400 to 20nm), all dynamic processes were found to speed up irrespective of the molecular architecture. The characteristic freezing temperatures of the α and the Debye-like processes followed the pore size dependence: Ta,D=Ta,D bulk-A/d1/2, where d is the pore diameter. The characteristic "freezing" temperatures for the Debye-like (the slow process for confined 1-propanol is non-Debye) and the α-processes decrease, respectively, by 6.5 and 13K in confined 1-propanol, by 9.5 and 19K in confined 2-ethyl-1-hexanol, and by 9 and 23K in confined 4-methyl-3-heptanol within the same 25nm pores. In 2-ethyl-1-hexanol, confinement reduced the number of linearly associated repeats from approximately heptamers in the bulk to dimers within 25 pores. In addition, the slower process in bulk 2-ethyl-1-hexanol and 4-methyl-3-heptanol, where the signal is dominated by ring-like supramolecular assemblies, is clearly non-Debye. The results suggest that the effect of confinement is dominant in the latter assemblies.

Bulk Processing of Multi-Temporal Modis Data, Statistical Analyses and Machine Learning Algorithms to Understand Climate Variables in the Indian Himalayan Region.

Studies relating to trends of vegetation, snowfall and temperature in the north-western Himalayan region of India are generally focused on specific areas. Therefore, a proper understanding of regional changes in climate parameters over large time periods is generally absent, which increases the complexity of making appropriate conclusions related to climate change-induced effects in the Himalayan region. This study provides a broad overview of changes in patterns of vegetation, snow covers and temperature in Uttarakhand state of India through bulk processing of remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) data, meteorological records and simulated global climate data. Additionally, regression using machine learning algorithms such as Support Vectors and Long Short-term Memory (LSTM) network is carried out to check the possibility of predicting these environmental variables. Results from 17 years of data show an increasing trend of snow-covered areas during pre-monsoon and decreasing vegetation covers during monsoon since 2001. Solar radiation and cloud cover largely control the lapse rate variations. Mean MODIS-derived land surface temperature (LST) observations are in close agreement with global climate data. Future studies focused on climate trends and environmental parameters in Uttarakhand could fairly rely upon the remotely sensed measurements and simulated climate data for the region.

Friction welding: An effective joining process for hybrid additive manufacturing

• Linear Friction Welding (LFW) demonstrated for hybrid additive manufactured (AM) parts. • Microstructure evolution compared between conventional and AM parts. • Temperature history predicted by finite element models correlated well with the microstructure changes. • The effects of process parameters on metallurgical evolution have been explained. Hybrid additive manufacturing combining bulk components from traditional manufacturing route can overcome the size limitation in typical metal additive process. Investigating the joining process of bulk and additive components is crucial in hybrid processes. In the present work, a comprehensive study, including both experiments and simulations, has been carried out to describe the linear friction welding of electron beam melted Ti6Al4V. Three different welding configuration have been considered: conventional-conventional, EBMelted to EBMelted and the dissimilar conventional-EBMelted. Successive weld joints were achieved in all the three configurations. The mechanical behavior and the phase transformation in the weld region is highly influenced by the base material microstructure. The thermo mechanical behaviour during the friction welding is simulated using finite element method. The temperature history is predicted with very good accuracy in all the three configurations. The experimental data along with the simulation results are used to further explain and understand the phenomena occurring during the welding.

Understanding crop processing and its social meaning in the Xinzhai period (1850\u20131750\xa0cal bce): a case study on the Xinzhai site, China

Although the Xinzhai period (1850–1750 cal bce) has been widely regarded as a critical time for the development of urbanization in China, little is known about the labour and social organization of the time. In this paper, archaeobotanical assemblages have been used to explore evidence of crop processing and they have provided further insights into the organization of labour and society at the Xinzhai site on the Central Plain of China. This is the first case study linking agricultural activities and social organization in the Xinzhai period. By discussing macro-botanical and phytolith results together, we conclude that the hulled cereals Setaria italica (foxtail millet), Panicum miliaceum (common or broomcorn millet) and Oryza sativa (rice), and the free-threshing pulse Glycine max (soybean) were all partly processed before storage to reduce labour demand in the harvest period. Since these summer-sown crops are all harvested in autumn, the practice of partial processing might imply that less labour was needed before storage. Thus, the labour for crop processing appears to have been organized on the basis of small production units such as households. This pattern is different from the communal bulk processing of crops before storage by the contemporary inhabitants of Dongzhao. Different patterns of social organization in various settlements in the Xinzhai period can thus be suggested. This conclusion contributes to a comprehensive understanding of the social development of communities living on the Central Plain and indicates that a steady increase in social complexity was very likely in the period before urbanization.

Quantifying Floating Plastic Debris at Sea Using Vessel-Based Optical Data and Artificial Intelligence

Despite recent advances in remote sensing of large accumulations of floating plastic debris, mainly in coastal regions, the quantification of individual macroplastic objects (&gt;50 cm) remains challenging. Here, we have trained an object-detection algorithm by selecting and labeling footage of floating plastic debris recorded offshore with GPS-enabled action cameras aboard vessels of opportunity. Macroplastic numerical concentrations are estimated by combining the object detection solution with bulk processing of the optical data. Our results are consistent with macroplastic densities predicted by global plastic dispersal models, and reveal first insights into how camera recorded offshore macroplastic densities compare to micro- and mesoplastic concentrations collected with neuston trawls.

Interfacial and Bulk Polarization of P(VDF-HFP) Investigated by Dielectric Spectroscopy

Capacitors in electrical and electronic systems composed of thin film dielectrics operate under extremely high electric fields. Dynamics of charge transport and relaxation are closely correlated to the energy storage properties and electrical degradation of thin film dielectrics for capacitive applications. In this paper, the dielectric relaxation properties of poly (vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) copolymer films are investigated over a broad frequency range from 10 mHz to 10 MHz and temperature range from -130 °C to 130 °C. The dielectric responses correlated to bulk and interfacial processes are clarified by varying the thickness and interfacial contact status of P(VDF-HFP) films. A low frequency process originating from the quasi-DC (QDC) process and a dielectric dispersion process correlated to the interfacial polarization are identified based on the Dissado-Hill dielectric response model and the equivalent circuit analysis. The high permittivity and high operation electric field of P(VDF-HFP) for capacitive energy storage give rise to improved blocking capacitance associated with the interface, suggesting the enhanced interfacial polarization. This work provides insights into the bulk and interface charge dynamics of polymer thin film dielectrics.

Critical Barriers to Successful Implementation of Earth-Abundant, Mn-Rich Cathodes for Vehicle Applications and Beyond: A Detailed Study of Low SOC Impedance

Earth-abundant, sustainable cathode chemistries based on Mn are increasingly attractive for enabling a broader portfolio of cathode oxides. The well-known class of lithium- and manganese-rich cathodes still represents very viable options. However, despite the important work on understanding the mechanisms of voltage fade, hysteresis, and oxygen activity, relatively little attention has been given to understanding the impedance characteristics of these electrodes. In particular, an anomalous rise in area specific impedance at lower states of charge, as well as overall impedance rise and surface damage due to electrolyte interactions, represent critical barriers to implementation. This work presents a comprehensive study of impedance behavior in cobalt-free, lithium- and manganese-rich electrodes. The use of a robust surface treatment allows for long-term behavior to be probed in the absence of surface damage, capacity loss, and impedance rise due to electrolyte interactions. The anomalous rise in impedance could not be correlated to surface changes, or surface phase formation, but could be directly correlated with the bulk processes of voltage fade and voltage hysteresis. The activated material can be explained as a percolating network of higher-voltage, layered-type sites having facile Li diffusion. Interspersed throughout this network are lower-voltage, disordered sites that represent a significant barrier.

Intrinsic Vulnerability to Soft Errors and a Mitigation Technique by Layout Optimization on DICE Flip Flops in a 65-nm Bulk Process

We found that specific pairs of pMOS and nMOS transistors in dual interlocked storage cell flip flop (DICEFF) become sensitive to soft errors by device simulations. We propose several layout structures that can improve soft-error tolerance with additional 39%-46% area overhead. We evaluated soft-error tolerance of a D-type FF (DFF) and DICEFFs in a 65-nm bulk process by heavy ions. Our experimental results showed that the DICEFF has more than 300× better soft-error tolerance than the DFF by Kr (LET 40.3 MeV·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /mg) irradiation when the supply voltage is 1.2 V, and the DICEFF has only 9× better soft-error tolerance than the DFF when the supply voltage is 0.6 V. However, the proposed DICEFF with 46% area overhead has 58× better soft-error tolerance than the DFF when the supply voltage is 0.6 V. DICEFF has so many sensitive pairs and lower soft-error tolerance as supply voltage decreases that cannot be applied to highly scaled process technologies.

Grain Temperature-Dependent Thermal Properties Estimation Using FI-QPSO Algorithm

Abstract A hybrid fuzzy inference-quantum particle swarm optimization (FI-QPSO) algorithm is developed to estimate the temperature-dependent thermal properties of the grain. The fuzzy inference scheme is established to determine the contraction-expansion coefficient according to the aggregation degree of particles. The heat transfer process in the grain bulk is solved using the finite element method, and the estimation task is formulated as an inverse problem. Numerical experiments are performed to study the effects of the surface heat flux, measurement errors, and the individual space on the estimation results. Comparison with the quantum particle swarm optimization (QPSO) algorithm and conjugate gradient method (CGM) is also conducted, and it shows the validity of the estimation method established in this paper.