Synergistic Blending Research Articles

Superprotonic Conductivity by Synergistic Blending of Coordination Polymers with Organic Polymers: Fabrication of Durable and Flexible Proton Exchange Membranes.

Creation of an efficient and cost-effective proton exchange membrane (PEM) has emerged as a propitious solution to address the challenges of renewable energy development. Coordination polymers (CPs) have garnered significant interest due to their multifunctional applications and moldability, along with long-range order. To leverage the potential of CPs in fuel cells, it is essential to integrate microcrystalline CPs into organic polymers to prepare membranes and avoid grain boundary issues. In this study, we designed and synthesized CPs containing imidazole and sulfonate moieties via gel-to-crystal transformation. The integration of CPs into the PVDF-PVP matrix resulted in superprotonic conductivity in the order of 10-2 S cm-1 at room temperature (30 °C) and 98 % RH. The proton conductivity achieved with CP-integrated composite membrane was 4.69×10-2 S cm-1 at 80 °C and 98 % RH, the highest among all CP/MOF-integrated PVDF-PVP membranes under hydrous conditions. The excellent compatibility of CPs with PVDF-PVP produced highly flexible membranes with superior mechanical, chemical, and thermal stability. About 25 times higher proton conductivity value was achieved with membrane, compared to intrinsic CPs, at RT and 98 % RH. Thus, we present a cost-effective CP-integrated mixed-matrix membrane with superprotonic conductivity and long-term durability for cutting-edge fuel cell development.

Enhancing photovoltaic efficiency in perovskite solar cells through synergistic blending of polyvinyl alcohol and F-127 polymer in a sandwich architecture

In the field of photovoltaics, perovskite solar cells (PSCs) have become increasingly popular because of their cost-effective processing and competitive efficiency when compared to silicon solar cells. This work presents a novel design of a PSC based on methyl ammonium lead iodide (CH3NH3PbI3) and investigates the possibilities of organic-inorganic metal halides in the field of PSCs. The device has a sandwich architecture, where the hole transport material (HTM) operates at room temperature using a blend of polyvinyl alcohol (PVA) and F-127 polymer. Under typical solar conditions, the built-in PSC, which has the architecture FTO/TiO2/Perovskite/PVA & F-127/Pt, exhibits a remarkable efficiency of 1.29 %. Interestingly, PSC stability at room temperature is still a major problem, yet our design demonstrates a remarkable 2-h stability in ambient circumstances. This accomplishment is ground breaking because it introduces a high-efficiency PSC in a sandwich construction operating in ambient settings for the first time. The fact that this novel technique is solution-based and does not require vacuum deposition lends even more credence to its viability and scalability.

Laboratory evaluation of synergistic blending with SBS-modified bitumen and rejuvenator to enhance the performance of recycled bitumen with a high content of RAP materials

Reclaimed asphalt pavement (RAP) stands as a pivotal construction material widely used in asphalt pavement rehabilitation. The prevailing focus and trajectory revolve around increasing the proportion and utility of RAP materials. However, the potential for temperature and fatigue cracking increases with the dosage of RAP materials. In this study, SBS modified bitumen (SBSMB) and four rejuvenators were combined synergistically with aged asphalt to enhance the performances of the recycled bitumen with high RAP content and consequently augment the value of the RAP material, all while ensuring compatibility between the SBSMB and aged base bitumen. Initially, the base bitumen was aged using a pressure aging vessel (PAV) test. Subsequently, a selection of virgin bitumen (VB), SBSMB, and four rejuvenators were utilized to revitalize the aged bitumen. A comprehensive battery of tests, encompassing conventional tests, temperature sweep, frequency sweep, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS), were carried out to characterize the rheological properties. Finally, Fourier transform infrared spectroscopy (FTIR) was employed, along with the determination of polystyrene index (IPS) and polybutadiene index (IPB), to evaluate the compatibility between SBSMB and aged base bitumen. The results underscore that the incorporation of SBSMB and rejuvenator comprehensively enhances high-temperature performance and fatigue cracking resistance while effectively reinstating low-temperature cracking resistance. Furthermore, the values of IPS, IPB, and IPS/IPB exhibit an increase with the addition of a rejuvenator, indicating its potential to improve the compatibility between SBSMB and aged base bitumen. Thus, this research proposes a more cost-effective and environmentally sustainable approach to bolstering conventional asphalt pavement performance and grade.

Production and optical characterisation of blended Polyethylene Terephthalate (PET)/Polyethylene Naphthalate (PEN) scintillator samples

In Particle and Nuclear Physics research and related applications, organic scintillators provide a cost-effective technology for the detection of ionising radiation. The next generation of experiments in this field is driving fundamental research and development on these materials, demanding improved light yield, radiation hardness, and fast response. Common materials such as PEN and PET have been found to offer scintillation properties competitive to commercial alternatives without the use of dopants. Motivated by their complementarity in terms of light yield, radiation hardness, and time response, there is an increasing interest in investigating PET:PEN mixtures to ascertain whether they exhibit synergistic blending. This paper presents results from the systematic development of samples of PET, PEN, and PET:PEN blends with varied mass proportions. The manufacturing technique, involving injection moulding of granule raw material, is detailed. The effects of doping the polymer base substrate with fluorescent dopants are explored. Finally, the emission spectra of the different material compositions and their relative light output are presented.

Diesel fuel properties of renewable polyoxymethylene ethers with structural diversity

Polyoxymethylene ethers (POMEs) are a class of low-soot and high-cetane oxygenate oligomers of structure RO-(CH2O–)n-R, with different chain lengths (n) and end-groups (R) that determine their diesel-like fuel properties. Commercial POMEs with methyl end-groups (MM-POME3-6) exhibit undesirably low energy density and high water solubility. A previous computational assessment indicated that the lower heating value (LHV) and water solubility for MM-POME3-6 both improve upon end-group exchange with larger butyl, iso-butyl and iso-pentyl end-groups. Here, we expanded upon our initial trans-acetalization reaction that employed 1-butanol to install butyl end-groups to also include branched, higher carbon-number end-groups using iso-butanol and fusel oil as reagents. These new products are termed iB*POME1-6, and FOil*POME1-5, respectively, and collectively referred to as R*POMEs. They possess the advantaged properties of the parent MM-POME3-6 while exhibiting higher LHV (31 MJ kg−1 and 28 MJ kg−1 for iB*POME1-6, and FOil*POME1-5, respectively) and much reduced water solubility (2.7 g L−1 and 1 g L−1 for iB*POME1-6, and FOil*POME1-5, respectively). Additional fuel property analyses were performed using 20 vol% blends of the R*POMEs with a base diesel fuel. Overall, the greater energy density and decreased water solubility of the R*POMEs, as well as their synergistic blending with diesel at moderate blend levels, provide the greatest benefits to consumers and position this group of products as an environmentally friendlier blendstock alternative to the commercially-available MM-POME3-6.

Identification of Key Drivers of Cost and Environmental Impact for Biomass-Derived Fuel for Advanced Multimode Engines Based on Techno-Economic and Life Cycle Analysis

Early stage research and development are needed to accelerate the introduction of advanced biofuel and engine technologies. Under the Co-Optima initiative, the U.S. Department of Energy is leveraging capabilities from its nine national laboratories and more than 35 university and industry partners including advanced computational tools, process design, data analysis, and economic and sustainability modeling tools to simultaneously design fuels and engines capable of running efficiently in an affordable, scalable, and sustainable way. In this work, we conducted techno-economic analysis (TEA) and life cycle assessment (LCA) to understand the cost, technology development, and environmental impacts of producing selected bioblendstocks for advanced engines such as multimode (MM) type engines at the commercial scale. We assessed 12 biofuel production pathways from renewable lignocellulosic biomass feedstocks using different conversion technologies (biochemical, thermochemical, or hybrid) to produce target co-optimized biofuels. TEA and LCA were used to evaluate 19 metrics across technology readiness, economic viability, and environmental impact and for each ranked on a set of criteria as favorable, neutral, unfavorable, or unknown. We found that most bioblendstocks presented in this study showed favorable economic metrics, while the technology readiness metrics were mostly neutral. The economic viability results showed potentially competitive target costs of less than $4 per gasoline gallon equivalent (GGE) for six candidates and less than $2.5/GGE for methanol. We identified 10 MM bioblendstock candidates with synergistic blending performance and with the potential to reduce greenhouse gas (GHG) emissions by 60% or more compared to petroleum-derived gasoline. The analysis presented here also provides insights into major economic and sustainability drivers of the production process and potential availability of the feedstocks for producing each MM bioblendstock.

Renaissance of Topotactic Ion-Exchange for Functional Solids with Close Packed Structures.

Recently, many new, complex, functional oxides have been discovered with the surprising use of topotactic ion‐exchange reactions on close‐packed structures, such as found for wurtzite, rutile, perovskite, and other structure types. Despite a lack of apparent cation‐diffusion pathways in these structure types, synthetic low‐temperature transformations are possible with the interdiffusion and exchange of functional cations possessing ns 2 stereoactive lone pairs (e. g., Sn(II)) or unpaired nd x electrons (e. g., Co(II)), targeting new and favorable modulations of their electronic, magnetic, or catalytic properties. This enables a synergistic blending of new functionality to an underlying three‐dimensional connectivity, i. e., [‐M−O‐M‐O‐] n , that is maintained during the transformation. In many cases, this tactic represents the only known pathway to prepare thermodynamically unstable solids that otherwise would commonly decompose by phase segregation, such as that recently applied to the discovery of many new small bandgap semiconductors.

Chemical kinetic basis of synergistic blending for research octane number

Utilizing kinetic simulations with the Co-Optimization of Fuels & Engines (Co-Optima) mechanism, the research octane number (RON) of various synergistic blendstocks at several blend levels in a four-component surrogate were predicted and compared against measured values. The blendstocks investigated include dimethylfuran (DMF), 2-methylfuran (2MF), prenol, 2-methyl-2-butene (2M2B), and ethanol—selected because of their nonlinear blending or synergistic behavior. The RON predictions are in excellent agreement with measured values for DMF and ethanol (within 2 RON units), with less satisfying results for 2MF and 2M2B (as much as 6 and 12 RON units off respectively). The predictions for prenol do not even capture the synergistic blending behavior observed experimentally, reflecting the fact that the kinetic model for prenol does not include sufficiently accurate low-temperature chemistry. The kinetic model was interrogated to understand the most important reactions consuming the blendstock and surrogate components, to understand the most important reactions responsible for the synergistic blending behavior. Better synergistic blenders scavenge hydroxyl radicals (OH) by addition reactions rather than hydrogen-abstraction (H-abstraction) reactions. In addition, those blendstocks, such as 2M2B, can form resonance-stabilized radical products, leading to superior RON boosting compared to ethanol. DMF and 2MF were shown to have the highest RON-boosting ability due to the rapid reaction of the OH addition products to other species that pull the OH addition equilibrium toward products.

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste-derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM "Fast Track" qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste-derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for "Fast Track." Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.

Impact of ethanol on oxidation of iso-octane at low and intermediate temperatures

This paper investigates the impact of ethanol on the oxidation of iso-octane at low and intermediate temperatures. Flow reactor experiments are conducted on binary mixtures ranging from neat iso-octane to neat ethanol at temperatures of 650 K and 875 K, a pressure of 10 bar and an equivalence ratio of 0.058, with the intermediate species and gas temperatures measured along the reactor. At 650 K, where neat iso-octane is near the peak of its low temperature chain branching, the addition of small amounts of ethanol dramatically suppresses iso-octane's reactivity and formation of intermediate species. Kinetic simulation reveals that this inhibition effect is a result of ethanol competing for OH radicals and producing an imbalance in OH formation, without affecting the iso-octane oxidation mechanism directly or altering its reaction flux distribution. By consuming more OH than it can produce, oxidation of ethanol progressively depletes OH in the radical pool, even at a low blending level, and leads to a strong reduction in the overall reactivity. In contrast, at 875 K, iso-octane and ethanol show comparable reactivities, and the formation of intermediate species correlates roughly linearly with the ethanol content, suggesting negligible interaction between the two fuels at intermediate temperatures. Overall, these results help to explain ethanol's inhibition on the knock propensity of iso-octane in spark ignition engines, as evidenced by the synergistic blending of the two fuels in octane numbers [1].

A modeling framework to evaluate blending of seawater and treated wastewater streams for synergistic desalination and potable reuse

A modeling framework was developed to evaluate synergistic blending of the waste streams from seawater reverse osmosis (RO) desalination and wastewater treatment facilities that are co-located or in close proximity. Four scenarios were considered, two of which involved blending treated wastewater with the brine resulting from the seawater RO desalination process, effectively diluting RO brine prior to discharge. One of these scenarios considers the capture of salinity-gradient energy. The other two scenarios involved blending treated wastewater with the intake seawater to dilute the influent to the RO process. One of these scenarios incorporates a low-energy osmotic dilution process to provide high-quality pre-treatment for the wastewater. The model framework evaluates required seawater and treated wastewater flowrates, discharge flowrates and components, boron removal, and system energy requirements. Using data from an existing desalination facility in close proximity to a wastewater treatment facility, results showed that the influent blending scenarios (Scenarios 3 and 4) had several advantages over the brine blending scenarios (Scenarios 1 and 2), including: (1) reduced seawater intake and brine discharge flowrates, (2) no need for second-pass RO for boron control, and (3) reduced energy consumption. It should be noted that the framework was developed for use with co-located seawater desalination and coastal wastewater reclamation facilities but could be extended for use with desalination and wastewater reclamation facilities in in-land locations where disposal of RO concentrate is a serious concern.

Guru vs. Google - New Challenges and Learning Trends

Educators and employers in most countries are getting uneasy on many fronts because of hurdles created by old textbook-based curricula and traditional mode of face-to-face (F2F) teaching which dominated education for the last two centuries. In this new century of the World Wide Web (WWW), increased global connectivity, availability of 4G/5G networks and exponential growth in the use of portable and smart devices is forcing countries around the world to upgrade their educational system for online learning. In USA, Europe, Australia and several other countries in Asia, educational institutions are rapidly integrating online learning into their academic programs and curricula. The speed of innovations leading to a synergistic blending of a variety of internet-based search engines, social media and rich digital content made available by MOOCs, edX, Khan Academy and other portals is quite overwhelming. It is becoming increasingly clear that this new combination is also changing the role of the Guru in educational processes. In India and elsewhere in Asia-Pacific region online learning is increasingly becoming a key factor for the growth of digital economy and sustainable development. New academic programs and curricula based on an increased emphasis on eLearning or digital learning will help new generation to successfully compete in digital economies and enhance strategic sustainable development not only in India but also elsewhere in the world. This paper also sheds some light on the importance of SMAC (Social, Mobile. Analytics and Cloud) in education, especially in higher education and how to use it for skill development (SD), a sector of human resource development neglected since the independence of India in 1947.

Discovery of novel octane hyperboosting phenomenon in prenol biofuel/gasoline blends

This work describes the first documented case of an effect defined herein as “octane hyperboosting” by an oxygenated fuel compound, 3-methyl-2-buten-1-ol (prenol). Octane hyperboosting is characterized by the Research Octane Number (RON) of a mixture (e.g. an oxygenate biofuel blended into gasoline) exceeding the RON of the individual components in that mixture. This finding counters the widely held assumption that interpolation between the RON values of a pure compound and the base fuel provides the bounds for the RON performance of the blend. This is clearly distinct from the more commonly observed synergistic blending of oxygenates with gasoline, where the RON never exceeds the performance of the highest performing component. Octane hyperboosting was observed for blends of prenol and six different gasoline fuels with varying composition. Testing of compounds chemically similar to prenol yielded no qualitatively similar instances of octane hyperboosting, which suggests that the effect may not be widespread among fuel candidates. The phenomenon suggests an unexplored aspect of autoignition kinetics research for fuel blends, and may provide a new mechanism for significantly increasing fuel octane number, which is necessary for increasing combustion efficiency in spark ignition engines. This phenomenon also increases the potential candidate list of biofuels, as compounds hitherto discounted due to their lower pure component RON may exhibit hyperboosting behavior, and thereby enhanced performance, in blends.

Evidence of compatibility and thermal stability improvement of poly(propylene carbonate) and polyoxymethylene blends

ABSTRACTPoly(propylene carbonate) (PPC) is a promising new sustainable polymer produced from carbon dioxide. PPC has inferior thermal stability which could be enhanced by synergistic blending with other polymers. Blends of PPC and the engineering thermoplastic polyoxymethylene are produced by melt compounding in various weight ratios. The compatibility of the blends is investigated using thermogravimetric analysis (TGA), differential scanning calorimetry, Fourier transform infrared spectroscopy (FTIR), density measurements, and scanning electron microscopy (SEM). TGA reveals that thermal stability of the blends increases dramatically in comparison to the neat PPC. A small shift in the glass transition temperature demonstrates the immiscibility of the blends but also indicates some compatibility, attributed to potential dipole–dipole interactions which are also corroborated with the FTIR results. A deviation of the rule of mixtures for density is found for some of the blends. SEM analysis of the blends shows two phase morphology; however, the interfacial adhesion appeared to be enhanced with increasing PPC content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45823.

Design of Iron-Based Nanomaterials As Catalysts for Efficient Water Treatment and Electrochemical Energy Conversion

Materials design for iron-based nanomaterials in water treatment and electrochemical energy conversion has largely remained two distinct fields of research and engineering. Yet, the overall goals are the same; materials must be highly active for the target reaction, chemically stable with relevant lifetimes, and tunable for broad applicability and optimization in engineering systems. Further, the detailed characterization performed on catalysts in the electrochemistry arena could benefit efforts to develop catalysts and reactive materials in the water treatment community. Our research focuses on the development of iron-based catalysts and reactive nanomaterials for water contaminant degradation and alkaline electrochemical energy conversion applications, where we synthesize and tune nanoparticle properties, such as phase, composition, and morphology, to target specific reactions. In this talk, I will discuss key examples of how we synthesize our nanomaterials, our work on understanding the roles of nanoparticle structure and composition in reactivity, and opportunities for the synergistic blending of materials design and knowledge of how to design iron-based nanocatalysts for water and energy applications. In particular, an understanding of nanoparticle composition and phase in bimetallic iron-nickel hydroxide nanoparticles for alkaline water electrolysis supports our efforts to design similar catalysts for reductive degradation of the contaminant trichloroethylene, and we are also investigating the role of conductivity in carbon support materials used for water treatment applications. Our work on understanding how nanoparticle synthesis parameters affect nanoparticle performance has led to identification of specific parameters that may be tuned to optimize our catalysts for both arenas, and we have identified specific ligands used during solution-phase synthesis that are important to our catalytic reactions of interest. Overall, there remain many opportunities to draw from experimental progress made in both the water treatment and electrochemistry research communities, and I will touch on several key opportunities that we see in our work.

Synergistic blending of high-valued heterocycles inhibits growth of Plasmodium falciparum in culture and P. berghei infection in mouse model

A series of phthalimide analogues, novelized with high-valued bioactive scaffolds was synthesized by means of click-chemistry under non-conventional microwave heating and evaluated as noteworthy growth inhibitors of Plasmodium falciparum (3D7 and W2) in culture. Analogues 6a, 6h and 6 u showed highest activity to inhibit the growth of the parasite with IC50 values in submicromolar range. Structure-activity correlation indicated the necessity of unsubstituted triazoles and leucine linker to obtain maximal growth inhibition of the parasite. Notably, phthalimide 6a and 6u selectively inhibited the ring-stage growth and parasite maturation. On other hand, phthalimide 6h displayed selective schizonticidal activity. Besides, they displayed synergistic interactions with chloroquine and dihydroartemisinin against parasite. Additional in vivo experiments using P. berghei infected mice showed that administration of 6h and 6u alone, as well as in combination with dihydroartemisinin, substantially reduced the parasite load. The high antimalarial activity of 6h and 6u, coupled with low toxicity advocate their potential role as novel antimalarial agents, either as standalone or combination therapies.

Probing enzyme-nanoparticle interactions using combinatorial gold nanoparticle libraries

The interaction of nanoparticles with proteins is extremely complex, important for understanding the biological properties of nanomaterials, but is very poorly understood. We have employed a combinatorial library of surface modified gold nanoparticles to interrogate the relationships between the nanoparticle surface chemistry and the specific and nonspecific binding to a common, important, and representative enzyme, acetylcholinesterase (AChE). We also used Bayesian neural networks to generate robust quantitative structure-property relationship (QSPR) models relating the nanoparticle surface to the AChE binding that also provided significant understanding into the molecular basis for these interactions. The results illustrate the insights that result from a synergistic blending of experimental combinatorial synthesis and biological testing of nanoparticles with quantitative computational methods and molecular modeling.

Fly Ash-Calcium Chloride Stabilization in Road Construction

Both fly ash and calcium chloride have been used in a wide variety of roadway construction applications. Engineering applications of both Class C and Class F fly ashes include portland cement concrete, soil and road base stabilization, flowable fills, grouts, structural fills, and asphalt filler. Until recently, the primary roadway application for calcium chloride has been as a dust-controlling agent on unsurfaced roads. Ongoing research at Texas A&M and Texas Transportation Institute has concluded that when the two are strategically combined within a roadway mix design, their individual mineralogical and physicochemical characteristics interact to further enhance the service performance of the roadway. Although the fines content in the roadbed composition is critical, there is a synergistic effect on the strength generated when calcium chloride is added along with fly ash. This synergistic blending of fly ash and calcium chloride is referred to as “surface-activated stabilization.’'

The effects of nitrogen and potassium nutrition on the growth of nonembryogenic and embryogenic tissue of sweet orange (Citrus sinensis (L.) Osbeck)

BackgroundMineral nutrients are one of the most basic components of plant tissue culture media. Nitrogen in the form of NH4+ and NO3- is the dominant mineral nutrient in most plant tissue culture formulations, with effects dependent on both the proportion and the amount of NH4+ and NO3-. The effects of nitrogen nutrition on the growth of nonembryogenic and embryogenic cell lines of sweet orange (C. sinensis (L.) Osbeck cv. 'Valencia'), tissues routinely used in citrus horticultural and plant improvement research, was explored using an experimental approach free of ion confounding that included a 2-component mixture (NH4+:K+) and a quantitative factor [NO3-] crossed by the mixture, thereby providing ion-specific estimates of proportional and amount effects.ResultsFirst, the linear mixture component, though only a comparison of the design space vertices, was highly significant for both tissue types and showed that NH4+ was required by both tissues. Second, the NH4+ * K+ mixture term was highly significant for both tissue types, revealing that NH4+ and K+ exhibit strong synergistic blending and showed that growth was substantially greater at certain blends of these two ions. Third, though the interaction between the NH4+:K+ mixture and NO3- amount on fresh weight accumulation for both tissue types was significant, it was substantially less than the main effect of the NH4+:K+ mixture. Fourth, a region of the design space was identified where fresh weight growth was increased 198% and 67% over the MS medium controls for nonembryogenic and embryogenic tissues.ConclusionBy designing a mineral nutrient experiment free of ion confounding, a direct estimation of ion-specific proportional and amount effects on plant tissue growth is possible. When the ions themselves are the independent factors and/or mixture components, the resulting design space can be systematically explored to identify regions where the response(s) is substantially improved over current media formulations. In addition, because the response is over a defined experimental region, a specific medium formulation is more accurately interpreted as a coordinate in the specified design geometry.

Invited commentary

Invited commentary