Chemical Engineering Commons^™

Challenges And Opportunities In Electrification Of Adsorptive Separation Processes, Abdullah Al Moinee, Ali A. Rownaghi, Fateme Rezaei

Chemical and Biochemical Engineering Faculty Research & Creative Works

A global energy transition from fossil-based to renewable-based systems requires advancements in various energy sectors. Current chemical separation processes are quite energy-intensive and require significant advancement to make this transition happen. In the energy transition era, reducing the dependency of separation processes on fossil-based thermal energy seems inevitable for transitioning smoothly and meeting the stringent timelines. In particular, adsorption-based separation processes have the potential to be fully electrified through innovative strategies in developing stimuli-responsive adsorbents and swing processes. In this review, we discuss the recent efforts in electrification of adsorption processes and provide an overview of emerging materials and processes. …

Highly Efficient Dopamine Sensing With A Carbon Nanotube-Encapsulated Metal Chalcogenide Nanostructure, Harish Singh, Jiandong Wu, Kurt A.L. Lagemann, Manashi Nath

Chemical and Biochemical Engineering Faculty Research & Creative Works

Carbon nanotube-encapsulated nickel selenide composite nanostructures were used as nonenzymatic electrochemical sensors for dopamine detection. These composite nanostructures were synthesized through a simple, one-step, and environmentally friendly chemical vapor deposition method, wherein the CNTs were formed in situ from pyrolysis of a carbon-rich metallo-organic precursor. The composition and morphology of these hybrid NiSe2-filled carbon nanostructures were confirmed by powder X-ray diffraction, Raman, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy images. Electrochemical tests demonstrated that the as-synthesized hybrid nanostructures exhibited outstanding electrocatalytic performance toward dopamine oxidation, with a high sensitivity of 19.62 μA μM-1 cm-2, low detection limit, broad linear …

Pd-Modified Cuo-Zno-Al2o3 Catalysts Via Mixed-Phases-Containing Precursor For Methanol Synthesis From Co2 Hydrogenation Under Mild Conditions, Xiao Fan, Kaiying Wang, Xiaoqing He, Shiguang Li, Miao Yu, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

A series of palladium-modified (Pd-modified) CuO-ZnO-Al2O3 (CZA) catalysts with various Pd loadings (0.3 wt% to 2.4 wt%) were prepared using the wetness impregnation method, on two CZA supports with different structures that are CZA-aged precursor composed of a mixture of zincian-malachite and hydrotalcite-like phases (CZA-zH), and CuO-ZnO-Al2O3 metal oxide nanoparticles (CZA-MO). Enhancement on catalytic activity can be observed on both Pd-modified CZA catalysts in a temperature range of 180–240 °C for methanol synthesis via CO2 hydrogenation. Pd/CZA-zH catalysts exhibited a more efficient and stable production of methanol at a relatively low reaction temperature of 180 °C for 100 hrs. of …

Advancement In Heavy Oil Upgrading And Sustainable Exploration Emerging Technologies, Youssef Yatimi, Jihane Mendil, Meena Marafi, Ahmed Alalou, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Upgrading heavy oil is a subject of high importance for fossil fuel industry due to the rapid depletion of light oil reservoirs and the consequent increased demand for upgrading heavy oil. In this review, the advancement made in heavy oil upgrading and the proposed sustainable emerging technologies dedicated to heavy oil processing have been discussed in a comprehensive and informative manner with consideration to the encountered associated with properties of heavy oil including its significant content of undesirable large molecular weight hydrocarbons, its high viscosity, and its elevated impurity level. The shortcomings of conventional crude oil upgrading technologies are outlined, …

Laboratory Evaluation Of High-Temperature Resistant Lysine-Based Polymer Gel Systems For Leakage Control, Tao Song, Xuyang Tian, Baojun Bai, Yugandhara Eriyagama, Mohamed Ahdaya, Adel Alotibi, Thomas P. Schuman

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

In-situ crosslinking gel known for its cost-effectiveness, has been employed for decades to plug high-permeability features in subsurface environments. However, some commonly used crosslinkers are being phased out due to the increasingly rigorous environmental regulations. As a newly discovered environmentally friendly crosslinker, lysine can crosslink the partially hydrolyzed polyacrylamide through transamidation reaction. The present work aimed to study the effect of polymer composition and concentration on the gelation behavior of lysine and high molecular weight acrylamide-based polymers. Several commercial high molecular weight polymers with different contents of 2-Acrylamido-2-methyl-1-propane sulfonic acid (AMPS) including AN-105/125, SAV-55/37/28, and SAV-10 were deployed in this …

Applications Of Plastics In The Automotive Industry: Current Trends And Future Perspectives, Hossein Abedsoltan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Plastics have transformed the automotive industry, contributing substantially to automobile design, weight reduction, fuel efficiency, safety, and sustainability. This review paper examines the applications of plastics in the automotive sector, evaluates the present trends, and describes the future plastic consumption possibilities, emphasizing emerging technology and sustainable practices. The paper delineates how plastics have become an essential component of automotive innovation and illustrates the possibilities for additional breakthroughs in this dynamic industry. Highlights: Advances in plastics, bioplastics, and smart materials in the auto industry. Plastic role in design, safety, and sustainability in the auto industry. Recycling and the circular economy of …

Influence Of Alkali Metal Cations On The Oxygen Reduction Activity Of Pt5Y And Pt5Gd Alloys, Kun-Ting Song, Alexandra Zagalskaya, Christian M. Schott, Peter M. Schneider, Batyr Garlyyev, Vitaly Alexandrov, Aliaksandr S. Bandarenka

Department of Chemical and Biomolecular Engineering: Faculty Publications

Electrolyte species can significantly influence the electrocatalytic performance. In this work, we investigate the impact of alkali metal cations on the oxygen reduction reaction (ORR) on active Pt₅Gd and Pt₅Y polycrystalline electrodes. Due to the strain effects, Pt alloys exhibit a higher kinetic current density of ORR than pure Pt electrodes in acidic media. In alkaline solutions, the kinetic current density of ORR for Pt alloys decreases linearly with the decreasing hydration energy in the order of Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺, whereas Pt shows the opposite trend. To gain …

An Overview Of Maternity Healthcare Monitoring In Developing Nations, Godphrey Kyambille

Tanzania Journal of Engineering and Technology (TJET)

A healthcare monitoring arrangement is essential for frequently monitoring a patient's health status. Specifically, maternal healthcare systems for tracking are utilized to evaluate the clinical status and monitor any abnormal condition changes during all three trimesters. This paper's objective is to conduct an extensive literature review and acknowledge earlier initiatives and studies conducted previously in maternal health care monitoring. This review focuses on accumulating information from earlier work and presents a general overview of previous studies concerning maternal health care monitoring (MHCM). The paper focuses on the maternal healthcare systems in developing countries accessed by pregnant women during the antenatal …

A Review Of Proton Exchange Membrane Degradation Pathways, Mechanisms, And Mitigation Strategies In A Fuel Cell, Dharmjeet Madhav, Junru Wang, Rajesh Keloth, Jorben Mus, Frank Buysschaert, Veerle Vandeginste

Department of Chemical and Biomolecular Engineering: Faculty Publications

Proton exchange membrane fuel cells (PEMFCs) have the potential to tackle major challenges associated with fossil fuel-sourced energy consumption. Nafion, a perfluorosulfonic acid (PFSA) membrane that has high proton conductivity and good chemical stability, is a standard proton exchange membrane (PEM) used in PEMFCs. However, PEM degradation is one of the significant issues in the long-term operation of PEMFCs. Membrane degradation can lead to a decrease in the performance and the lifespan of PEMFCs. The membrane can degrade through chemical, mechanical, and thermal pathways. This paper reviews the different causes of all three routes of PFSA degradation, underlying mechanisms, their …

Development Of Inorganically Cross-Linked Sulfonated Polyacrylamide Preformed Particle Gels For Conformance Control: Impact Of Anionic Groups, Reem Elaf, Ahmed Hamza, Hassan Nimir, Mohammed Saad, Ibnelwaleed A. Hussein, Baojun Bai

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Modern oil and gas extraction faces challenges, notably from the surplus of produced water, hampering hydrocarbon recovery and raising environmental and economic concerns. A promising solution is the injection of preformed particle gels (PPGs) into the reservoir's fractures and high permeability zones, facilitating production processes. This study introduces a novel class of inorganically cross-linked PPGs with exceptionally high swelling capacities, comprising sulfonated polyacrylamide cross-linked with aluminum attached to acetate, nitrate, sulfate, and lactate anions individually. These PPGs function as superabsorbents, capable of absorbing water at a ratio of 100-700 times their dry weight while maintaining adequate gel strength up to …

Physio-Chemical Modifications To Re-Engineer Small Extracellular Vesicles For Targeted Anticancer Therapeutics Delivery And Imaging, Rahmat Asfiya, Lei Xu, Anjugam Paramanantham, Kuanysh Kabytaev, Anna Chernatynskaya, Grace Mccully, Hu Yang, Akhil Srivastava

Chemical and Biochemical Engineering Faculty Research & Creative Works

Cancer theranostics developed through nanoengineering applications are essential for targeted oncologic interventions in the new era of personalized and precision medicine. Recently, small extracellular vesicles (sEVs) have emerged as an attractive nanoengineering platform for tumor-directed anticancer therapeutic delivery and imaging of malignant tumors. These natural nanoparticles have multiple advantages over synthetic nanoparticle-based delivery systems, such as intrinsic targeting ability, less immunogenicity, and a prolonged circulation time. Since the inception of sEVs as a viable replacement for liposomes (synthetic nanoparticles) as a drug delivery vehicle, many studies have attempted to further the therapeutic efficacy of sEVs. This article discusses engineering strategies …

Rab7 Deficiency Impairs Pulmonary Artery Endothelial Function And Promotes Pulmonary Hypertension, Bryce Piper, Srimathi Bogamuwa, Tanvir Hossain, Daniela Farkas, Lorena Rosas, Adam C. Green, Geoffrey Newcomb, Nuo Sun, Jose A. Ovando-Ricardez, Jeffrey C. Horowitz, Aneel R. Bhagwani, Hu Yang, Tatiana V. Kudryashova, Mauricio Rojas

Chemical and Biochemical Engineering Faculty Research & Creative Works

Pulmonary arterial hypertension (PAH) is a devastating and progressive disease with limited treatment options. Endothelial dysfunction plays a central role in the development and progression of PAH, yet the underlying mechanisms are incompletely understood. The endosome-lysosome system is important to maintain cellular health, and the small GTPase RAB7 regulates many functions of this system. Here, we explored the role of RAB7 in endothelial cell (EC) function and lung vascular homeostasis. We found reduced expression of RAB7 in ECs from patients with PAH. Endothelial haploinsufficiency of RAB7 caused spontaneous pulmonary hypertension (PH) in mice. Silencing of RAB7 in ECs induced broad …

Estimation Of Co2 Absorption By A Hybrid Aqueous Solution Of Amino Acid Salt With Amine, Farid Amirkhani, Amir Dashti, Hossein Abedsoltan, Amir H. Mohammadi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Four developed machine learning algorithms are proposed to prognosticate the CO₂ solubility in amino acid salt solutions, blended with amine solutions as additives, in broad ranges of temperature and pressure. From literature 375 experimental data points for CO₂ solubility were collected. The results from the applied algorithms indicated that the CO₂ solubility is estimated acceptably close to the experimental values. In the best case, the developed network estimates CO₂ solubility in the stated solutions with an average relative deviation of 6.53 % and a correlation coefficient of 0.9892.

Biomolecular Crystals As Functional Materials, Fahmeed Khan Sheehan

Dissertations, Theses, and Capstone Projects

The field of supramolecular chemistry has undergone significant evolution over the last few decades, progressing from fundamental studies of self-assembling systems to the rational design of functional materials with exceptional properties. Among these materials, short peptides have emerged as a chemically simple yet highly versatile class of biomimetic compounds. Initially, short peptides were used as model systems to understand larger protein interactions. As the field progressed, short peptides were found to have exceptional functionality, and are now explored as functional nanomaterials for diverse applications. In many cases, short peptide materials have displayed properties not found in biology, in some cases …

Reactive Capture And Conversion Of Co2 Into Hydrogen Over Bifunctional Structured Ce1-Xcoxnio3/Ca Perovskite-Type Oxide Monoliths, Khaled Baamran, Shane Lawson, Ali A. Rownaghi, Fateme Rezaei

Chemical and Biochemical Engineering Faculty Research & Creative Works

Carbon capture, utilization, and storage (CCUS) technologies are pivotal for transitioning to a net-zero economy by 2050. In particular, conversion of captured CO₂ to marketable chemicals and fuels appears to be a sustainable approach to not only curb greenhouse emissions but also transform wastes like CO₂ into useful products through storage of renewable energy in chemical bonds. Bifunctional materials (BFMs) composed of adsorbents and catalysts have shown promise in reactive capture and conversion of CO₂ at high temperatures. In this study, we extend the application of 3D printing technology to formulate a novel set of BFMs composed …

Efficient Discovery And Industrialized Manufacture Of Terpenoids, Haoming Chi, Liying Er, Tiangang Liu

Bulletin of Chinese Academy of Sciences (Chinese Version)

Terpenoids, a class of chemical entities with diverse biological activities in nature, demonstrate significant potential for applications in fields such as drug discovery, flavor industry, and agriculture. However, traditional methods face challenges, including inefficiency and high costs, in the discovery and industrialization of terpenoids. The rapid development of synthetic biology, genomics, artificial intelligence, and automation provides new opportunities for efficient terpenoid discovery and industrialization. This study comprehensively analyzes how these technologies synergistically contribute to the discovery, optimization, and large-scale production of terpenoids, and summarizes the current high-yield situations of terpenoids. The aim is to propose innovative strategies to accelerate technological …

Retraction Notice To “High Density Conductive Lifepo4 Cathode With Enhanced High-Rate And High Temperature Performance” [Mater. Chem. Phys. 232 (2019) 367–373, (S0254058419304110), (10.1016/J.Matchemphys.2019.05.014)], David Seung-Hyun Lee, Won Bin Im, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. The Editor-in-Chief found that the corresponding author of this article submitted the manuscript to the journal without the consent of the two individuals named as "co-authors", using invented email addresses to impersonate them. In addition, based on the raw materials presented to the journal by the second co-author and the Editor-in-Chief's own investigation, the Editor-in-Chief believes that some results in the paper are fabricated. Based on these two findings, the Editor-in-Chief has decided to retract the …

Scaffold-Based 3d Cell Culture Models In Cancer Research, Waad H. Abuwatfa, William G. Pitt, Ghaleb A. Husseini

Faculty Publications

Three-dimensional (3D) cell cultures have emerged as valuable tools in cancer research, offering significant advantages over traditional two-dimensional (2D) cell culture systems. In 3D cell cultures, cancer cells are grown in an environment that more closely mimics the 3D architecture and complexity of in vivo tumors. This approach has revolutionized cancer research by providing a more accurate representation of the tumor microenvironment (TME) and enabling the study of tumor behavior and response to therapies in a more physiologically relevant context. One of the key benefits of 3D cell culture in cancer research is the ability to recapitulate the complex interactions …

Strain-Dependent Activity-Stability Relations In Ruo2 And Iro2 Oxygen Evolution Catalysts, Payal Chaudhary, Alexandra Zagalskaya, Herbert Over, Vitaly Alexandrov

Department of Chemical and Biomolecular Engineering: Faculty Publications

Strain engineering is an effective strategy in modulating activity of electrocatalysts, but the effect of strain on electrochemical stability of catalysts remains poorly understood. In this work, we combine ab initio thermodynamics and molecular dynamics simulations to examine the role of compressive and tensile strain in the interplay between activity and stability of metal oxides considering RuO₂ and IrO₂ as exemplary catalysts. We reveal that although compressive strain leads to improved activity via the adsorbate-evolving mechanism of the oxygen evolution reaction, even small strains should substantially destabilize these catalysts promoting dissolution of transition metals. In contrast, our results …

Process Simulation For Converting Co2 Emissions From The Cementindustry To Dimethyl Ether, Nour Abou Seada, Dina Aboelela

Biochemical Engineering

Climate change is the leading severe problem in the twenty-first century, which is associated with greenhouse gas emissions,carbon dioxide that is the foremost cause of global warming and super greenhouse effect. In this concern, to avoid hazardousproblems, the steady stream of CO2 effluents existing in the atmosphere must be transformed to beneficial products for beingused as an abundant chemical feedstock. Implementing a new green strategy, which is known for the catalytic hydrogenationof CO2 into alternative fuels and valuable chemicals, will be a long-lasting solution to alleviate CO2 emissions. In this paper,a process simulation showing the synthesis of dimethyl ether (DME) …

Synthetic Approaches Of Carbohydrate Based Self-Assembling Systems, Guijun Wang, Anji Chen, Pramod Aryal, Jonathan Bietsch

Chemistry & Biochemistry Faculty Publications

Carbohydrate-based self-assembling systems are essential for the formation of advanced biocompatible materials via a bottom-up approach. The self-assembling of sugar-based small molecules has applications encompassing many research fields and has been studied extensively. In this focused review, we will discuss the synthetic approaches for carbohydrate-based self-assembling (SA) systems, the mechanisms of the assembly, as well as the main properties and applications. This review will mainly cover recent publications in the last four years from January 2020 to December 2023. We will essentially focus on small molecule self-assembly, excluding polymer-based systems, which include various derivatives of monosaccharides, disaccharides, and oligosaccharides. Glycolipids, …

Valorization Of Bourbon Distilling Waste Using Thermal Conversion Processes For Nutrient-Rich Food Products, Tosin Olayemi Olanrewaju

Theses and Dissertations--Biosystems and Agricultural Engineering

The Commonwealth of Kentucky accounts for over 95% of global bourbon production. A primary byproduct of bourbon production is stillage, which has a very high moisture content (91–94%) and high biochemical oxygen demand, making it challenging to manage. The recent expansion of the bourbon industry has heightened environmental concerns regarding the best methods to handle this byproduct. Dewatering and drying of stillage produce distillers' spent grains (DSG-B), which are rich in dietary fiber and protein and could serve as an excellent source of functional fiber in human nutrition.

This study examined the approach for dewatering, drying, inclusion of DSG-B as …

Borate-Based Bioactive Glasses Properties: Clinical And Biomedical Applications, Sarah Fakher, David J. Westenberg

Biological Sciences Faculty Research & Creative Works

Borate bioactive glasses (BBGs) constitute the recently produced bioactive glasses (BGs) in the domain of bioactive materials, offering enhanced functionalities over conventional silicate and phosphate BGs. This advancement is primarily characterized by BBGs' rapid yet controllable degradation rates, superior bioactivity, and the ability to swiftly form a hydroxyapatite layer (HAP) upon interaction with physiological fluids. A distinguishing feature of BBGs lies in their customizability; doping with therapeutic metal ions tailors their bioactivity towards specific physiological responses, including promoting angiogenesis, antibacterial activity, and osteogenesis. This versatility of BBGs' applications extends to bone regeneration, wound healing, drug delivery systems, and potentially nerve …

Effects Of Energy Drink Additives On Crayfish Metabolism, Katherine Paltz

Williams Honors College, Honors Research Projects

The effects of caffeine and additives commonly found in energy drinks were tested on crayfish to record changes, if any, in their metabolism. Three experimental groups were studied: 1. Caffeine; 2. Caffeine + Glucuronolactone; 3.) Caffeine + Glucuronolactone + Taurine. Caffeine is a common stimulant used to improve mental awareness, headaches, memory, and athletic performance. Glucuronolactone is connected with cardiovascular issues and aggressive behavior. Taurine is said to improve mood and focus. The experiment was performed at two different caffeine levels: 600mg and 1200mg for an initial 1 hour of exposure and 10 hours after exposure used as a pseudo-baseline. …

Exploring Natural Raw Materials For The Development Of Hot Melt Adhesives For Linings Of Paintings, Erica Factor

Williams Honors College, Honors Research Projects

Natural raw materials will be explored for developing hot melt adhesives for the lining of paintings. The leading raw material is a natural resin called "Damar". This resin is obtained from the tree family Dipterocaupocea in India and Southeast Asia. This material has shown promising results from initial testing. Damar, with the potential for other natural raw materials, will be combined with synthetic ingredients to create sustainable formulations. The formulations will be tested on linen to replicate the application onto paintings. The sustainability, tackiness, texture, and overall performance of each formula will be considered. Once a formulation has been selected, …

Determination Of Spore Viability In Concrete Across Several Factors Using Most Probable Number, Samuel Boyer

Williams Honors College, Honors Research Projects

To determine the lowest concentration of spore added to polyurethane-cement composite (PUCCO) particles that can still germinate after curing in concrete. This research project is a small addition to the larger research project being undertaken by Mirza Mohammed Rashiduzzaman for his Masters. The larger project involves the use of fungal spores added in concrete to act as a self-healing component when cracks form in the concrete structure over time. These spores are suspended in a protective oil and loaded into small, hardened sponge-like PUCCO cubes to act as growth points when water and air can reach the PUCCO in the …

Aggregation-Induced Emission Probe For Alzheimer's Detection And Treatment Screening, Gemini Ramlo

Williams Honors College, Honors Research Projects

The proposed project is to research if ROF-2, an aggregation-induced emitter, can be used to screen medications for Alzheimer's Disease and to accurately detect this disease, along with its progression. This will be done through multiple incubation periods using different identifiers that have already been solidified within Alzheimer's research to prove its ability and accuracy within screening and detection regarding this disease.

Novel Re-Crosslinkable Preformed Particle Gels (Rppg) For Parent- And Infill-Well-Fracture Interactions Mitigation, Xiaojing Ge, Adel Alotibi, Ahmed Al-Hlaichi, Yanbo Liu, Tao Song, Junchen Liu, Baojun Bai, Thomas P. Schuman

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Hydraulic fracturing treatments in unconventional infill (or "child") wells can be significantly affected by depletion from existing parent-well, resulting in asymmetrical fracture growth. These issues may lead to excessive load-water production, proppant deposition, casing deformation in the parent well, and unbalanced stimulation of infill wells. To mitigate these effects, various strategies have been proposed, including the use of far-field diverters in child wells and repressurization of parent wells. Additionally, an increasingly popular strategy involves injecting near-wellbore diverters to temporarily plug entry points into the parent wellbores during frac operations on infill wells. To achieve better application, a novel low-cost, self-degradable, …

Flow Regimes In Bubble Columns With And Without Internals: A Review, Ayat N. Mahmood, Amer A. Abdulrahman, Laith S. Sabri, Abbas J. Sultan, Hasan Shakir Majdi, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrodynamics characterization in terms of flow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies. This review presents recent studies on the typical flow regimes established in bubble columns. Some effort is also provided to introduce relevant definitions pertaining to this field, namely, that of "void fraction" and related (local, chordal, cross-sectional and volumetric) variants. Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail. In the second part of the review, the attention is shifted to cases with internals of various types (perforated …

Thermal Decomposition And Kinetic Parameters Of Three Biomass Feedstocks For The Performance Of The Gasification Process Using A Thermogravimetric Analyzer, Rania Almusafir, Joseph D. Smith

Chemical and Biochemical Engineering Faculty Research & Creative Works

Thermogravimetric analysis (TGA) is a powerful technique and useful method for characterizing biomass as a non-conventional fuel. A TGA apparatus has been utilized to experimentally investigate the impact of biomass feedstock diversity on the performance of the gasification of hardwood (HW), softwood (SW) pellets, and refuse-derived fuel (RDF) materials. The solid conversion rate and the volatile species formation rate have been estimated to quantify the rates of devolatilization for each material. In addition, the combustion kinetic characteristics of the three biomass feedstocks were investigated using TGA at different heating rates, and a thermal kinetic analysis was conducted to describe the …