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A membrane condenser (MC) is a novel membrane separation technology that utilizes the hydrophobic nature of porous membranes to capture water vapor from humid gas. Factors such as temperature, pressure, flow rate, and gas composition entering the membrane condenser play a crucial role in water recovery efficiency. This study utilized hydrophobic polytetrafluoroethylene (PTFE) hollow fiber membranes to create multiple identical membrane modules. This research investigated the impact of temperature, flow rate, pressure on the intake side, gas flow on the cooling side, membrane area, and other variables on the performance of the membrane condenser process. This study compared water extraction efficiency under different conditions, focusing on feed flow temperature and sweeping flow. Results showed that at a temperature of 60 °C, the water recovery rate was 24.7%, while a sweep gas flow rate of 4 L/min resulted in a recovery rate of 22.7%. The efficiency of the membrane condenser decreased with higher feed flow rates but increased with larger membrane areas. A proportional relationship between inlet flow and membrane area was observed, suggesting an optimal range of 0.51-0.67 cm/s for both parameters. These findings offer valuable insights for the practical implementation of hydrophobic membrane-based membrane condenser technology.

Ethylene-chlorotrifluoroethylene (ECTFE) was first commercialized by DuPont in 1974. Its unique chemical structure gives it high heat resistance, mechanical strength, and corrosion resistance. But also due to these properties, it is difficult to prepare a membrane from it by the nonsolvent-induced phase separation (NIPS) method. However, it can be prepared as a microfiltration membrane using the thermally induced phase separation (TIPS) method at certain temperatures and with the selection of suitable solvents, and the use of green solvents is receiving increasing attention from researchers. The surface wettability of ECTFE membranes usually needs to be modified before use to strengthen its performance to meet the application requirements, usually by graft modification and surface oxidation techniques. This paper provides an overview of the structure of ECTFE and its preparation and modification methods, as well as recent advances in its application areas and prospects for the future methods of preparing high-performance ECTFE membranes.

A high-performance polypropylene hollow fiber membrane (PP-HFM) was prepared by using a binary environmentally friendly solvent of polypropylene as the raw material, adopting the thermally induced phase separation (TIPS) method, and adjusting the raw material ratio. The binary diluents were soybean oil (SO) and acetyl tributyl citrate (ATBC). The suitable SO/ATBC ratio of 7/3 was based on the size change of the L-L phase separation region in PP-SO/ATBC thermodynamic phase diagram. Through the characterization and comparison of the basic performance of PP-HFMs, it was found that with the increase of the diluent content in the raw materials, the micropores of outer surface of the PP-HFM became larger, and the cross section showed a sponge-like pore structure. The fluoropolymer, Hyflon ADx, was deposited on the outer surface of the hollow fiber membrane using a physical modification method of solution dipping. After modification, the surface pore size of the Hyflon AD40L modified membranes decreased; the contact angle increased to around 107°; the surface energy decreased to 17 mN·m -1 ; and the surface roughness decreased to 17 nm. Hyflon AD40L/PP-HFMs also had more water resistance properties from the variation of wetting curve. For biocompatibility of the membrane, the adsorption capacity of the modified PP membrane for albumin decreased from approximately 1.2 mg·cm -2 to 1.0 mg·cm -2 , and the adsorption of platelets decreased under fluorescence microscopy. The decrease in blood cells and protein adsorption in the blood prolonged the clotting time. In addition, the hemolysis rate of modified PP membrane was reduced to within the standard of 5%, and the cell survival rate of its precipitate was above 100%, which also indicated the excellent biocompatibility of fluoropolymer modified membrane. The improvement of hydrophobicity and blood compatibility makes Hyflon AD/PP-HFMs have the potential for application in membrane oxygenators.

Aniline is a highly toxic organic pollutant with "carcinogenic, teratogenic and mutagenesis" characteristics. In the present paper, a membrane distillation and crystallization (MDCr) process was proposed to achieve zero liquid discharge (ZLD) of aniline wastewater. Hydrophobic polyvinylidene fluoride (PVDF) membranes were used in the membrane distillation (MD) process. The effects of the feed solution temperature and flow rate on the MD performance were investigated. The results showed that the flux of the MD process was up to 20 L·m -2 ·h -1 and the salt rejection was above 99% under the feeding condition of 60 °C and 500 mL/min. The effect of Fenton oxidation pretreatment on the removal rate of aniline in aniline wastewater was also investigated, and the possibility of realizing the ZLD of aniline wastewater in the MDCr process was verified.

Water scarcity raises important concerns with respect to human sustainability and the preservation of important ecosystem functions. To satisfy water requirements, seawater desalination represents one of the most sustainable solutions. In recent decades, membrane distillation has emerged as a promising thermal desalination process that may help to overcome the drawbacks of traditional desalination processes. Nevertheless, in membrane distillation, the temperature at the feed membrane interface is significantly lower than that of the bulk feed water, due to the latent heat flux associated with water evaporation. This phenomenon, known as temperature polarization, in membrane distillation is a crucial issue that could be responsible for a decay of about 50% in the initial transmembrane water flux. The use of plasmonic nanostructures, acting as thermal hotspots in the conventional membranes, may improve the performance of membrane distillation units by reducing or eliminating the temperature polarization problem. Furthermore, an efficient conversion of light into heat offers new opportunities for the use of solar energy in membrane distillation. This work summarizes recent developments in the field of plasmonic-enhanced solar evaporation with a particular focus on solar-driven membrane distillation applications and its potential prospects.

Integrated wastewater treatment processes are accepted as the best option for sustainable and unrestricted onsite water reuse. In this study, moving bed biofilm reactor (MBBR), membrane bioreactor (MBR), and direct contact membrane distillation (DCMD) treatment steps were integrated successively to obtain the combined advantages of these processes for industrial wastewater treatment. The MBBR step acts as the first step in the biological treatment and also mitigates foulant load on the MBR. Similarly, MBR acts as the second step in the biological treatment and serves as a pretreatment prior to the DCMD step. The latter acts as a final treatment to produce high-quality water. A laboratory scale integrated MBBR/MBR/DCMD experimental system was used for assessing the treatment efficiency of primary treated (PTIWW) and secondary treated (STIWW) industrial wastewater in terms of permeate water flux, effluent quality, and membrane fouling. The removal efficiency of total dissolved solids (TDS) and effluent permeate flux of the three-step process (MBBR/MBR/DCMD) were better than the two-step (MBR/DCMD) process. In the three-step process, the average removal efficiency of TDS was 99.85% and 98.16% when treating STIWW and PTIWW, respectively. While in the case of the two-step process, the average removal efficiency of TDS was 93.83% when treating STIWW. Similar trends were observed for effluent permeate flux values which were found, in the case of the three-step process, 62.6% higher than the two-step process, when treating STIWW in both cases. Moreover, the comparison of the quality of the effluents obtained with the analysed configurations with that obtained by Jeddah Industrial Wastewater Treatment Plant proved the higher performance of the proposed membrane processes.

Poly(ethylene-chlorotrifluoroethylene) (ECTFE) membrane is a hydrophobic membrane material that can be used to recover water from high-humidity gases in the membrane condenser (MC) process. In this study, ECTFE membranes were prepared by the thermally induced phase separation (TIPS) method using the green binary diluents triglyceride diacetate (TEGDA) and trioctyl trimellitate (TOTM). Thermodynamic phase diagrams of the ECTFE/TEGDA: TOTM system were made. The effects of the diluent composition and cooling rate on the structure and properties of the ECTFE membranes were investigated by characterizing the SEM, contact angle, mechanical properties, pore size and porosity. The results showed that ECTFE membranes with cellular structure were successfully prepared and exhibit good mechanical properties. Moreover, increasing the TOTM content in the binary diluents and decreasing the cooling rate could effectively improve the mean pore size of the ECTFE membranes, but the increase in TOTM content reduced the mechanical properties. During the MC process, the water recovery performance of ECTFE membranes increased with the increase in the mean pore size of the membranes, and the condensation flow and water recovery of membrane prepared at 20% TOTM were 1.71 kg·m -2 ·h -1 and 54.84%, respectively, which were better than the performance of commercial hydrophobic PVDF membranes in the MC. These results indicated that there is good potential for the application of ECTFE membranes during the MC process.

Technological progress has made chemistry assume a role of primary importance in our daily life. However, the worsening of the level of environmental pollution is increasingly leading to the realization of more eco-friendly chemical processes due to the advent of green chemistry. The challenge of green chemistry is to produce more and better while consuming and rejecting less. It represents a profitable approach to address environmental problems and the new demands of industrial competitiveness. The concept of green chemistry finds application in several material syntheses such as organic, inorganic, and coordination materials and nanomaterials. One of the different goals pursued in the field of materials science is the application of GC for producing sustainable green polymers and membranes. In this context, extremely relevant is the application of green chemistry in the production of imprinted materials by means of its combination with molecular imprinting technology. Referring to this issue, in the present review, the application of the concept of green chemistry in the production of polymeric materials is discussed. In addition, the principles of green molecular imprinting as well as their application in developing greenificated, imprinted polymers and membranes are presented. In particular, green actions (e.g., the use of harmless chemicals, natural polymers, ultrasound-assisted synthesis and extraction, supercritical CO 2 , etc.) characterizing the imprinting and the post-imprinting process for producing green molecularly imprinted membranes are highlighted.

Due to the good hydrophobicity and chemical resistance of poly(ethylene trifluoroethylene) (ECTFE), it has been an attractive potential material for microfiltration, membrane distillation and more. However, few porous hydrophobic ECTFE membranes were prepared by thermally induced phase separation (TIPS) for membrane condenser applications. In this work, the diluent, di-n-octyl phthalate (DnOP), was selected to prepare the dope solutions. The calculated Hassen solubility parameter indicated that ECTFE has good compatibility with DnOP. The corresponding thermodynamic phase diagram was established, and it has been mutually verified with the bi-continuous structure observed in the SEM images. At 30 wt% ECTFE, the surface contact angle and liquid entry pressure reach their maximum values of 139.5° and 0.71 MPa, respectively. In addition, some other basic membrane properties, such as pore size, porosity, and mechanical properties, were determined. Finally, the prepared ECTFE membranes were tested using a homemade membrane condenser setup. When the polymer content is 30 wt%, the corresponding results are better; the water recovery and condensed water yield is 17.6% and 1.86 kg m -2 h -1 , respectively.

The creation of partial or complete human epidermis represents a critical aspect and the major challenge of skin tissue engineering. This work was aimed at investigating the effect of nano- and micro-structured CHT membranes on human keratinocyte stratification and differentiation. To this end, nanoporous and microporous membranes of chitosan (CHT) were prepared by phase inversion technique tailoring the operational parameters in order to obtain nano- and micro-structured flat membranes with specific surface properties. Microporous structures with different mean pore diameters were created by adding and dissolving, in the polymeric solution, polyethylene glycol (PEG Mw 10,000 Da) as porogen, with a different CHT/PEG ratio. The developed membranes were characterized and assessed for epidermal construction by culturing human keratinocytes on them for up to 21 days. The overall results demonstrated that the membrane surface properties strongly affect the stratification and terminal differentiation of human keratinocytes. In particular, human keratinocytes adhered on nanoporous CHT membranes, developing the structure of the corneum epidermal top layer, characterized by low thickness and low cell proliferation. On the microporous CHT membrane, keratinocytes formed an epidermal basal lamina, with high proliferating cells that stratified and differentiated over time, migrating along the z axis and forming a multilayered epidermis. This strategy represents an attractive tissue engineering approach for the creation of specific human epidermal strata for testing the effects and toxicity of drugs, cosmetics and pollutants.

Membrane crystallization (MCr) is a promising and innovative process for the recovery of freshwater from seawater and for the production of salt crystals from the brine streams of desalination plants. In the present work, composite polymeric membranes for membrane crystallization were fabricated using graphene and bismuth telluride inks prepared according to the wet-jet milling (WJM) technology. A comparison between PVDF-based membranes containing a few layers of graphene or bismuth telluride and PVDF-pristine membranes was carried out. Among the 2D composite membranes, PVDF with bismuth telluride at higher concentration (7%) exhibited the highest flux (about 3.9 L∙m -2 h -1 , in MCr experiments performed with 5 M NaCl solution as feed, and at a temperature of 34 ± 0.2 °C at the feed side and 11 ± 0.2 °C at the permeate side). The confinement of graphene and bismuth telluride in PVDF membranes produced more uniform NaCl crystals with respect to the pristine PVDF membrane, especially in the case of few-layer graphene. All the membranes showed rejection equal to or higher than 99.9% (up to 99.99% in the case of the membrane with graphene). The high rejection together with the good trans-membrane flux confirmed the interesting performance of the process, without any wetting phenomena, at least during the performed crystallization tests.

The formation of heat stable salts (HSS) during the natural gas sweetening process by amine solvent causes many problems such as corrosion, foaming, capacity reduction, and amine loss. A modeling study was carried out for the removal of HSS ions from amine solution using nanofiltration (NF) membrane process that ensures the reuse of amine solution for gas sweetening. This model studies the physics of the nanofiltration process by adjusting and investigating pore radius, the effects of membrane charge, and other membrane characteristics. In this paper, the performance of the ternary ions was investigated during the removal process from methyl di-ethanol amine solution by the nanofiltration membrane process. Correlation between feed concentration and permeate concentration, using experimental results with mathematical correlation as C i,p = f (C i,f ) was used in modeling. The results showed that the calculated data from the model provided a good agreement with experimental results (R 2 = 0.90-0.75). Also, the effect of operating conditions (including feed pressure and feed flow rate on ions rejection and recovery ratio across the flat-sheet membrane) was studied. The results showed that the recovery and rejection ratios of the NF membrane depend on the driving pressure across the membrane. While the driving pressure is affected by the feed flow conditions and feed pressure.

A proper validation of an engineered brain microenvironment requires a trade of between the complexity of a cellular construct within the in vitro platform and the simple implementation of the investigational tool. The present work aims to accomplish this challenging balance by setting up an innovative membrane platform that represents a good compromise between a proper mimicked brain tissue analogue combined with an easily accessible and implemented membrane system. Another key aspect of the in vitro modelling disease is the identification of a precise phenotypic onset as a definite hallmark of the pathology that needs to be recapitulated within the implemented membrane system. On the basis of these assumptions, we propose a multiplex membrane system in which the recapitulation of specific neuro-pathological onsets related to Alzheimer's disease pathologies, namely oxidative stress and β-amyloid 1-42 toxicity, allowed us to test the neuroprotective effects of trans-crocetin on damaged neurons. The proposed multiplex membrane platform is therefore quite a versatile tool that allows the integration of neuronal pathological events in combination with the testing of new molecules. The present paper explores the use of this alternative methodology, which, relying on membrane technology approach, allows us to study the basic physiological and pathological behaviour of differentiated neuronal cells, as well as their changing behaviour, in response to new potential therapeutic treatment.

Under the notion of water-energy nexus, the unsustainable use of water in power plants has been largely accepted in silence. Moreover, the evaporated water from power plants acts as a primary nucleation source of particulate matter (PM), rendering significant air pollution and adverse health issues. With the emergence of membrane-based dehydration processes such as vapor permeation membrane, membrane condenser, and transport membrane condenser, it is now possible to capture and recycle the evaporated water. Particularly, the concept of transport membrane condensers (TMCs), also known as membrane heat exchangers, has attracted a lot of attention among the membrane community. A TMC combines the advantages of heat exchangers and membranes, and it offers a unique tool to control the transfer of both mass and energy. In this review, recent progress on TMC technology was critically assessed. The effects of TMC process parameters and membrane properties on the dehydration efficiencies were analyzed. The peculiar concept of capillary condensation and its impact on TMC performance were also discussed. The main conclusion of this review was that TMC technology, although promising, will only be competitive when the recovered water quality is high and/or the recovered energy has some energetic value (water temperature above 50 ∘C).

The present work has undertaken a meticulous glance on optimizing the performance of an SGMD configuration utilized a porous poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF- co -HFP) membrane. This was carried out by conducting a systematic framework for investigating and optimizing the pertinent parameters such as sweeping gas flow rate, feed temperature, feed concentration and feed flow rate on the permeate flux. For this purpose, the Taguchi method and design of experiment techniques were harnessed to statistically determine optimum operational conditions. Besides that, a comprehensive surface and permeation characterization was conducted against the hand-made membranes. Results showcased that the membrane performance was ultimately controlled by the feed temperature and was nearly (~680) % higher when the temperature raised from 45 to 65 °C. Also, to a lesser extent, the system was dominated by the feed flow rate. As the adopted feed flow rate increases (from 0.2 to 0.6 L/min), around 47.5% increment was bestowed on water permeability characteristics. In contra, 34.5% flux decline was witnessed when higher saline feed concentration (100 g/L) was utilized. In the meantime, with raising the sweeping gas flow rate (from 120 to 300 L/h), the distillate was nearly 129% higher. Based on Taguchi design, the maximum permeate flux (17.3 and 17 kg/m 2 ·h) was secured at 35 g/L, 0.4 L/min, 65 °C and 300 L/h, for both commercial and prepared membranes, respectively.

Research activities on the application of direct contact membrane distillation (DCMD) for processing at low temperature (up to 50 °C) solutions containing urea were presented and discussed. Feeds were urine (also in mixture) and human plasma ultrafiltrate. Moreover, as a case study, the performance of membrane modules of different sizes and features was investigated for reaching the productivities needed in the treatment of the human plasma ultrafiltrate. In particular, two modules were equipped with the same type of capillaries, but differed in terms of membrane area, while the third module contained a different type of membranes and presented a membrane area in between those of the two previous modules. The three modules were compared, at a parity of operating temperatures and streams velocity, in terms of transmembrane flux, permeate production and size, underlining the directions to follow for a real implementation of the technique.

The creation of a liver tissue that recapitulates the micro-architecture and functional complexity of a human organ is still one of the main challenges of liver tissue engineering. Here we report on the development of a 3D vascularized hepatic tissue based on biodegradable hollow fiber (HF) membranes of poly(ε-caprolactone) (PCL) that compartmentalize human hepatocytes on the external surface and between the fibers, and endothelial cells into the fiber lumen. To this purpose, PCL HF membranes were prepared by a dry-jet wet phase inversion spinning technique tailoring the operational parameters in order to obtain fibers with suitable properties. After characterization, the fibers were applied to generate a human vascularized hepatic unit by loading endothelial cells in their inner surface and hepatocytes on the external surface. The unit was connected to a perfusion system, and the morpho-functional behavior was evaluated. The results demonstrated the large integration of endothelial cells with the internal surface of individual PCL fibers forming vascular-like structures, and hepatocytes covered completely the external surface and the space between fibers. The perfused 3D hepatic unit retained its functional activity at high levels up to 18 days. This bottom-up tissue engineering approach represents a rational strategy to create relatively 3D vascularized tissues and organs.

An integrated membrane process for the treatment of wastewaters from a flue gas desulfurization (FGD) plant was implemented on a laboratory scale to reduce their salt content and to produce a water stream to be recycled in the power industry. The process is based on a preliminary pretreatment of FGD wastewaters, which includes chemical softening and ultrafiltration (UF) to remove Ca 2+ and Mg 2+ ions as well as organic compounds. The pretreated wastewaters were submitted to a reverse osmosis (RO) step to separate salts from water. The RO retentate was finally submitted to a membrane distillation (MD) step to extract more water, thus increasing the total water recovery factor while producing a high-purity permeate stream. The performance of RO and MD membranes was evaluated by calculating salts rejection, permeate flux, fouling index, and water recovery. The investigated integrated system allowed a total recovery factor of about 94% to be reached, with a consequent reduction of the volume of FGD wastewater to be disposed, and an MD permeate stream with an electrical conductivity of 80 μS/cm, able to be reused in the power plant, with a saving in fresh water demand.

This work focuses on the study of the mass transfer of arsenic(V) through asymmetric polyvinylidene fluoride hollow-fiber membrane contactors using Aliquat-336 as an extractant. In the first part of this work, the fibers were prepared and characterized by SEM and by determining their thickness and porosity. From SEM pictures, an asymmetric structure was obtained that was characterized by an inner sponge-like structure and outer finger-like structure with a pore radius and porosity about 0.11 µm and 80%, respectively. In the second part, the prepared fibers were used as membrane contactors for the study of mass transfer of arsenic(V), investigating the effect of several parameters such as pH, temperature, and initial concentration of the feed. The overall mass transfer coefficient of As(V) was around 6 × 10 ⁻6 cm/s.

The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications., Competing Interests: The authors declare no conflict of interest.

In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability., Competing Interests: The authors declare no conflict of interest.

This work provides additional insights into the identification of operating conditions necessary to overcome a current limitation to the scale-up of the breath figure method, which is regarded as an outstanding manufacturing approach for structurally ordered porous films. The major restriction concerns, indeed, uncontrolled touching droplets at the boundary. Herein, the bulk of polymeric solutions are properly managed to generate honeycomb membranes with a long-range structurally ordered texture. Water uptake and dynamics are explored as chemical environments are changed with the intent to modify the hydrophilic/hydrophobic balance and local water floatation. In this context, a model surfactant such as the polyoxyethylene sorbitan monolaurate is used in combination with alcohols at different chain length extents and a traditional polymer such as the polyethersufone. Changes in the interfacial tension and kinematic viscosity taking place in the bulk of composite solutions are explored and examined in relation to competitive droplet nucleation and growth rate. As a result, extensive structurally ordered honeycomb textures are obtained with the rising content of the surfactant while a broad range of well-sized pores is targeted as a function of the hydrophilic-hydrophobic balance and viscosity of the composite polymeric mixture. The experimental findings confirm the consistency of the approach and are expected to give propulsion to the commercially production of breath figures films shortly.

Produced water represents the largest wastewater stream from oil and gas production. Generally, its high salinity level restricts the treatment options. Membrane crystallization (MCr) is an emerging membrane process with the capability to extract simultaneously fresh water and valuable components from various streams. In the current study, the potential of MCr for produced water treatment and salt recovery was demonstrated. The experiments were carried out in lab scale and semi-pilot scale. The effect of thermal and hydrodynamic conditions on process performance and crystal characteristics were explored. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed that the recovered crystals are sodium chloride with very high purity (>99.9%), also indicated by the cubic structure observed by microscopy and SEM (scanning electron microscopy) analysis. It was demonstrated experimentally that at recovery factor of 37%, 16.4 kg NaCl per cubic meter of produced water can be recovered. Anti-scaling surface morphological features of membranes were also identified. In general, the study provides a new perspective of isolation of valuable constituents from produced water that, otherwise, is considered as a nuisance.

This paper deals with a theoretical investigation of gas transport properties in a pure and modified PEBAX block copolymer membrane with N-ethyl-o/p-toluene sulfonamide (KET) as additive molecules. Molecular dynamics simulations using COMPASS force field, Gusev-Suter Transition State Theory (TST) and Monte Carlo methods were used. Bulk models of PEBAX and PEBAX/KET in different copolymer/additive compositions were assembled and analyzed to evaluate gas permeability and morphology to characterize structure-performance relationships.