Reset

Advanced Filters
Emerging Areas & New Methods in Biological Chemistry: Emerging Areas and New Methods
10:30am - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Mark D Distefano, Organizer, Univ of Minnesota; Phoebe Glazer, Organizer, University of Kentucky; Ekaterina Pletneva, Organizer, Dartmouth College; Phoebe Glazer, Presider, University of Kentucky
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual
Division/Committee: [BIOL] Division of Biological Chemistry

This symposium will showcase new directions and methods in research in biological chemistry

Sunday
Chemical biology approaches for tackling hematologic disorders
10:30am - 10:55am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Laura Dassama, Presenter
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual
Disorders that arise from mutations in the beta subunit of hemoglobin (such as sickle cell disease and beta-thalassemia) affect millions of people around the world. While few therapies exist to treat these diseases, it has been known for decades that production of fetal hemoglobin, in which the beta subunit is replaced with gamma, reduces disease severity. In spite of this, there are no broadly effective and easily accessible fetal hemoglobin inducers. In this lecture, I will describe the use of chemical biology strategies to induce fetal hemoglobin by modulating the functions, at the protein level, of key transcriptional regulators of fetal hemoglobin. We posit that these studies will be leveraged for the development of new effective and accessible therapies to tackle the hematologic disorders.
Sunday
A small molecule redistributes iron from liver to erythroblasts via transferrin-dependent pathway in ferroportin-deficient mice
10:55am - 11:10am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual
Genetic or induced deficiencies of the transmembrane iron exporting protein ferroportin (FPN1) causes the iron misdistribution that underlies Anemia of Inflammation (AoI) and Ferroportin Disease (FD) in humans. A small molecule natural product, hinokitiol, was previously shown to serve as a surrogate transmembrane iron transporter that can restore hemoglobinization in DMT1- or mitoferrin-deficient zebrafish. Here we show that in FPN1-deficient flatiron mice hinokitiol redistributes iron from liver to red blood cells and thereby restores hemoglobinization. We also have further characterized the corresponding mechanism; hinokitiol first releases iron trapped within liver macrophages, then hinokitiol-Fe complexes transfer iron to transferrin (Tf), and finally the resulting Fe-Tf complexes drive red blood cell maturation in a transferrin receptor (TfR)-dependent manner. These findings provide foundational support for the use of small molecule as a molecular prosthetic to address a range of human diseases caused by iron misdistribution.
Sunday
Withdrawn
11:10am - 11:35am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual

Sunday
Molecular glue discovery by high throughput nL chemistry
11:35am - 12:00pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual
Molecular glues are an important novel modality in medicinal chemistry. Blockbuster such as lenalidomide and pomalidomide work on the glue principle by generating a novel interaction between the Ikaros/Aiolos substrate and the E3 ligase cereblon. “Immediate Drop on Demand Technology” (I-DOT) is a nano-dispensing technology and has been mostly applied to analytical and biological questions. This technique could be combined with multicomponent reaction (MCR) to help rapidly build lenalidomide or pomalidomide analogs library. Here, we introduce a practical multicomponent reaction approach to synthesize high diversity pomalidomide analogs employing a one-pot Ugi reaction and Ugi-tetrazole reaction. We prepared 384 different derivatives on a nanoscale in a fully automated fashion by I-DOT. We performed the cell viability screening for the I-DOT synthetic plate and found that many compounds showed better or similar inhibition potency against MM1S cell line compared to the pomalidomide and lenalidomide. Therefore, we selected 19 compounds that showed better inhibition potency and degradation kinetics against MM1S cell line and exemplified the resynthesis on a millimole scale featuring good yield. Finally, we rescreened the resynthesis compound by western blot to testify the degradation of the substrates.
In summary automated high throughput synthesis and screening allows for unprecedented fast molecular glue discovery.

Sunday
Withdrawn
12:00pm - 12:15pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual

Sunday
Role of progesterone receptor (PGR) as a master regulator genes in women’s infertility: A bioinformatic approach
12:15pm - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 24
Division: [BIOL] Division of Biological Chemistry
Session Type: Oral - Virtual
Couples who fail to get pregnant after one year of unprotected intercourse and have tested positive for normal sperm motility, ovulation, and unobstructed fallopian tubes are diagnosed with unexplained infertility (UI). Pregnancy in a woman depends on the menstrual cycle, which is regulated by the homeostasis balance of four main hormones: progesterone, estrogen, follicle-stimulating hormone and luteinizing hormone. There are only a few reports about the dysregulations in the balance of these hormones and especially about the role of the progesterone receptor (PGR) in the female reproductive system. Furthermore, the PGR predominant and relevant character is well known in proliferation and differentiation during the the reproductive cycle and pregnancy. To elucidate the checkpoints in PGR pathway infertility intervention, we aim to identify key genes impared in female infertility processes and in particular those in close relation with PGR and inflammation pathways.
The preliminary help us identified the involved mechanisms and molecules (i.e., estrogen receptor (ER), CYP19A1 and LIF). Overall In general, there was a total of 91 genes associated with PGR and from those, 80 were directly connected with angiogenesis and inflammation. Due to the large number of possible interactions within the genes associated with UI, it was necessary to classify them according to annotations with the aid of the GeneCards Inferred Functionality Scores (GIFtS) algorithm and the physiological processes associated with them. The first phase of our approach confirmed the relevance of progesterone in female infertility processes. In a second phase, we quantified the relevance of PGR in infertility processes via network analysis aided by network indicators such as the betweenness centrality and degree, all together to estimate the interplay of the possible targets. This approach organizes the genes association in nodes and their close relation with a particular pathway obtained from GeneCards and IMEx databases. The graphical representation of the network was conducted with the Cytoscape software. The preliminary results indicate that genes with marked interactions with PGR are EGFR, GRB2, TRAF2 and MDFI. This suggests that the studied dysregulation might be related to decidualization, progesterone signaling pathway, cell survival and trophoblast differentiation.

Multiscale Modeling in Heterogeneous Catalysis:
10:30am - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
fanglin che, Organizer, University of Massachusetts Lowell; Alexander Mironenko, Organizer, University of Illinois at Urbana-Champaign; Alexander Mironenko, Presider, University of Illinois at Urbana-Champaign; fanglin che, Presider, University of Massachusetts Lowell
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Division/Committee: [CATL] Division of Catalysis Science & Technology

In silico design of novel catalytic materials hinges on the availability of accurate and representative multiscale models of complex catalytic phenomena. By providing a link between first-principles estimates of elementary thermodynamic and kinetic parameters and the macroscopic reactor behavior, such models hold promise to bridge pressure and material gaps in heterogeneous catalysis and thereby enable experimentally testable predictions. This symposium will promote exchange of ideas and knowledge on methodology and applications of multiscale models in heterogeneous catalysis.

Sunday
AI-enabled prediction of subnanometer catalyst stability and dynamics
10:30am - 10:50am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Dionisios Vlachos, Presenter
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Observing catalysts under reaction conditions is generally difficult. Several spectroscopic methods are performed in situ rather than operando. As a result, there is strong debate about the catalyst stability. Computational methods can provide insights into the catalyst stability and dynamics but are typically plagued by the multiscale nature of phenomena and the complex and combinatorial number of the structures of catalysts. In this talk we present an AI-enabled multiscale framework to understand the stability and dynamics of subnanometer catalysts.
Sunday
Distributed parallelisation of kinetic Monte-Carlo simulations for heterogeneous catalysis with the time-warp algorithm
10:50am - 11:10am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Kinetic Monte-Carlo (KMC) simulations have been instrumental in multiscale catalysis studies by elucidating the complex dynamics of heterogeneous catalysts and translating nanoscale reactive events to macroscopic performance metrics, such as activity and selectivity. However, the accessible length- and time-scales are still limited. In fact, handling lattices containing millions of sites with “traditional” sequential KMC implementations becomes challenging due to the large memory requirements and the heavy computational demand.
On the other hand, parallelisation approaches based on domain decomposition techniques are quite challenging to implement in KMC simulation due to the inherently sequential nature thereof, by which one reactive event is causally linked to future (and past) events. These causal relations, in combination with the random time advancement in each KMC step, necessitate sophisticated protocols for conflict resolution at the boundaries between subdomains. The so-called Time-Warp algorithm offers a way towards addressing this challenge with local operations: sending and receiving messages and anti-messages (the latter encoding “undo” actions), saving snapshots of the simulation state, as well as rolling-back in time and reinstating a previous state. Thus, any causality violations, arising transiently during simulation, are corrected, and the exact dynamics of the underlying stochastic model (the master equation) are faithfully reproduced.
In this work, we have coupled the Time-Warp algorithm with the Graph-Theoretical KMC framework making it possible to handle complex adsorbate lateral interactions and reaction events within very large lattices. This approach has been implemented in Zacros, our general-purpose KMC software, and been validated and benchmarked for efficiency in model systems as well as realistic chemistries. This work makes Zacros the first-of-its-kind general-purpose KMC code with distributed parallelisation capability to study heterogeneous catalysts.

Sunday
MD simulations with chemical accuracy: Alkane reactivity in acidic zeolites
11:10am - 11:30am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Fabian Berger, Presenter, Humboldt University of Berlin; Marcin Rybicki; Joachim Sauer
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Adsorption is a fundamental step in heterogeneous catalysis that strongly affects the reaction kinetics and diffusion within the catalyst, but inherently poses a multiscale problem. While the dynamic behavior of adsorbates can only be properly described by approaches that sample for long times, e.g. Molecular Dynamics (MD) simulations, a chemically accurate description of explicit adsorbate-host interactions requires methods beyond density functional theory (DFT).
The standard approach to calculate adsorption enthalpies considers only the energetically most stable structure (“static” approach) on the potential energy surface (PES) and is based on DFT augmented with dispersion terms (DFT-D). It is currently almost exclusively used, despite its shortcomings: (i) semi-empirical description dispersion, (ii) self-interaction correction errors when performed with GGA functionals, (iii) improper sampling of the configurational space, and (iv) harmonic partition functions.
While adsorption enthalpies calculated via the standard approach largely deviate from experiments, MD simulations at the DFT-D level account for finite temperature effects but are still far from reaching chemical accuracy. To approach chemical accuracy, post-Hartree-Fock methods, e.g. MP2, are required, but limited to a small number of calculations which are not sufficient to get converged enthalpies.
We introduce a combined hybrid MP2:PBE+D2 MD approach that overcomes the problems of standard DFT-D calculations. While the sampling of the configurational space is computed with MDs at the PBE+D2 level, the enthalpies are based on fitted MP2:PBE+D2 energy surfaces. MP2 corrections to the adsorption enthalpy are only calculated for selected snapshots and used to parametrize a 2-dimensional linear model of physically motivated structure parameters. This model is used to calculate MP2 corrections for each step of the MD, effectively reducing the computation time for a “MP2-quality” MD of 100,000 steps from about 340 years to 3 weeks. We illustrate the accuracy and robustness of this approach by calculating alkane adsorption enthalpies in different zeolites, at varying temperatures, and Brønsted acid site densities. For all investigated systems, chemically accurate adsorption enthalpies have been obtained. Furthermore, the adsorption enthalpies have been used to obtained intrinsic reaction barriers for alkane cracking in H-MFI with unprecedented accuracy, improving rate constants by a factor of 50.

Sunday
Understanding the role of solvent effects in the thermal and electrochemical hydrogenation of organics
11:30am - 11:50am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Contrary to solid/gas interfaces, in solid/liquid interfaces the molecules in the liquid can be organized such that those near the surface are appreciably different from the bulk. This can be impacted by: the composition of the liquid phase, the size shape and loading of nanoparticles and the hydro/lipophilicity of the support. In this talk. we will outline the findings from our ongoing studies of both thermal and electrochemically driven hydrogenation of organic molecules. We will present both classical and ab into molecular dynamics calculations that simulate the structure and composition within the double both at the support as well as on surface of catalytic nanoparticles. The calculations explicitly identify the different roles of entropy and binding energy on the activity and selectivity of solution phase hydrogenation. A first example shows how H2 adsorption on Pt(111) becomes appreciably weaker in the presence of water as compares with vapor phase. phenol/water mixtures behave on hydrophilic and lipophilic surfaces and provides a possible explanation as to why a higher phenol hydrogenation conversion is observed on Pd catalysts on hydrophilic surfaces than on lipophilic surfaces. We show how reaction rates can be manipulated by changing the concentration of phenol adjacent to the catalysts through modification of the degree of support hydrophilicity, size and loading of nanoparticles, and temperature. We also discuss the role of water in changing the adsorption free energetics on Pt surface. In a final example, we simulate the speciation on metal and/or graphitic carbon cathodes of a complex solvent mixture containing organics, salts, acids, as a function of cathode charge and temperature. Here we show that the ability to transfer an electron to the organic is governed by the amount of organic in the double layer as well as its orientation with respect to the electrode surface.

Sunday
Selective methane to methanol converion on metal oxide catalysts
11:50am - 12:10pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Erwei Huang, Stony Brook University; Ping Liu, Presenter, Brookhaven National Laboratory
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
The development of variable catalysts to promote the methane activation and control the conversion selectivity has long been a challenge in catalysis. One of the obstacles is the lacking in fundamental understanding of reaction network due to the complexity. Here, the selective oxidation of methane by oxygen and/or water to methanol will be presented using combined Density Functional Theory and kinetic Monte Carlo simulation. Our results not only provide new insight into the mechanism and active sites, but also highlight the importance of choice of oxidizing agent in tuning the catalytic selectivity.
Sunday
Discovering terpene catalysis inside nano-capsules with multiscale modeling and experiments
12:10pm - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 25
Shani Zev; Efrat Pahima; Prof. Dan Major, Presenter, Bar Ilan University
Division: [CATL] Division of Catalysis Science & Technology
Session Type: Oral - Virtual
Large-scale production of natural products, such as terpenes, presents a significant scientific and technological challenge. One promising approach to tackle this problem is chemical synthesis inside nano-capsules, although enzyme-like control of such chemistry has not yet been achieved. In order to better understand the complex chemistry inside nano-capsules, we design a multiscale nano-reactor simulation approach. The nano-reactor simulation protocol consists of hybrid quantum mechanics-molecular mechanics-based high temperature Langevin molecular dynamics simulations. Using this approach we model the tail-to-head formation of monoterpene and sesquiterpenes inside a resorcin[4]arene-based capsule (capsule I). We provide a rationale for the experimentally observed kinetics of terpene product formation and product distribution using capsule I. Based on the in-capsule I simulations, and mechanistic insights, we propose that one can also predict product distributions inside the capsule.

Innovation: The Chemical Professional's Response to the Global Pandemic:
10:30am - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Mary K Carroll, Organizer, Presider, Union College; Adam Myers, Organizer, SSCI, a Division of AMRI; Elizabeth Nalley, Organizer, Cameron University
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual
Division/Committee: [COMSCI] Committee on Science

The global pandemic had an enormous impact on how science is done, science is taught and science is communicated. To continue with their work, chemical professionals had to innovate. And innovate they did. This symposium will highlight successes facilitated by, rather than challenges posed by, COVID-19 restrictions. What can we take from these experiences as we reshape what it means to conduct and convey science?

Sunday
Introductory Remarks
10:30am - 10:35am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual

Sunday
COVID 19-changing the way we teach organic chemistry labs
10:35am - 10:55am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Elizabeth Nalley, Presenter, Cameron University
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual

COVID-19 arrived in Oklahoma during March of 2019. Cameron students and faculty were on Spring Break. We were notified on Thursday that classes would be held on virtually beginning the Monday after Spring Break. We had four days to revise our courses including our laboratories so that we could continue to offer courses in chemistry at Cameron. We were forced to innovate and become magicians’ over-night. It was one of the most difficult and challenging experiences I have dealt with in my teaching career. This presentation will describe the changes we made in our organic chemistry laboratories to offer them as virtual labs and at the same time teach our students some basic organic chemistry techniques.

Sunday
Research opportunities offered by COVID-19
10:55am - 11:15am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Dr. Donna J Nelson, Presenter, University of Oklahoma
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual
Every problem is an opportunity in disguise, and COVID-19 is no exception. Surveys exploring student's attitudes and opinions had been initiated before COVID-19 and were continued through the pandemic. Data from the study will be discussed.
Sunday
Navigating collaboration during tides of change
11:15am - 11:35am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Isabella Goodenough, Presenter; Dr. Julian A Bobb, Presenter, Virginia Commonwealth University
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual
The COVID-19 pandemic challenged us to think outside the box about how we meet and communicate. While in-person meetings were not possible throughout most of 2020, virtual meetings emerged as a viable alternative. The virtual platform provided a new way to meet, share ideas, and collaborate between sections. A number of local section Younger Chemists Committees (YCC) embraced the opportunity to work together to provide camaraderie and professional development to students and early career professionals. The Eastern U.S. Younger Chemists Committee Partnership unites eight YCC groups and four international groups. The partnership has provided countless professional development programs and networking opportunities, ranging from Building Confidence and Self-Care Sundays to Presenting Scientific Data and the popular Day in the Life series. These programs are fully funded by two Members Engaging Through Technology (METT) grants. Join us to learn how the team was formed, the programs developed, how effective communication and teamwork have been managed across different time zones, and the future direction of the partnership.
Sunday
Virtual meetups: Uniting the biocatalysis and protein engineering community in 2020 and beyond
11:35am - 11:55am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Ania Fryszkowska, Presenter; Alison Narayan, Presenter
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual
As COVID-19 forced our research community out of the lab and into lockdown, traditional opportunities to interact with fellow scientists disappeared. In April 2020, industrial and academic scientists sought to provide a forum for early-career scientists to present their research and interact with the broader community, starting a monthly online symposium series in the area of biocatalysis and protein engineering. Over a year later, the monthly event continues with a community that is perhaps more united than ever.
Sunday
Preprints in the chemistry community
11:55am - 12:15pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Prof. Francois-Xavier Coudert, Presenter, CNRS / PSL University
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual
The field of chemistry has seen a rapid increase in preprint adoption in the past few years, mostly due to the combined effect of the development of community preprint servers, and journals shifting their editorial policies to become more preprint-friendly. Preprints, combined with comment-hosting platforms and social media, allow for quick and broad dissemination of a research team’s latest results, as well as feedback from the community. The overall process replicates some aspects typically associated with conference talks, posters and even informal social interactions, such as coffee breaks. The way in which scientific results are disseminated has changed significantly with the advent of the internet and preprints represent an important step in the evolution of scholarly communication. This is particularly relevant with the current wave of travel restrictions related to the COVID-19 outbreak, as rapid dissemination of results at conferences (including talks and posters) is limited. Preprints offer an alternative road toward dissemination, particularly attractive to early-career researchers or researchers with limited funding for travel.
<i>Distribution of subject areas of preprints posted on ChemRxiv as of April 2020.</i>

Distribution of subject areas of preprints posted on ChemRxiv as of April 2020.


Sunday
Discussion
12:15pm - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 41
Division: [COMSCI] Committee on Science
Session Type: Oral - Virtual

Disinfection Byproducts in Drinking Water & Wastewater: Detection, Formation & Control:
10:30am - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: B401
Susan Richardson, Organizer; Chii Shang, Organizer, The Hong Kong University of Sci. Technol.; Paul Westerhoff, Organizer, Arizona State Univ; Prof. Xin Yang, Organizer, Sun Yat-sen University, Environmental Science; Susan Richardson, Presider, University of South Carolina
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Co-sponsor/Theme: Theme: Sustainability
Division/Committee: [ENVR] Division of Environmental Chemistry

This symposium will focus on the identification of emerging DBPs, the latest advances in the underlying chemistry of DBPs formation and technologies in eliminating DBP risks in water and wastewater treatment.

Sunday
Introductory Remarks
10:30am - 10:35am USA / Canada - Eastern - August 22, 2021 | Room: B401
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid

Sunday
Occurrence of bromine and iodine in drinking water supplies
10:35am - 11:05am USA / Canada - Eastern - August 22, 2021 | Room: B401
Paul Westerhoff, Presenter, Arizona State Univ; Naushita Sharma, Arizona State University
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Bromine (Br) and iodine (I) species are one of the primary pre-cursors for the formation of potentially toxic brominated and iodinated disinfection by-products(Br/I-DBPs) in finished drinking waters. While significant effort has characterized organic precursors in drinking water treatment plants (DWTP) source waters, limited information is available on inorganic DBP precursors, specifically Br and I species. Our study presents result from non-targeted spatial and temporal occurrence surveys from over 700 newly collected samples from ~200 water utilities in USA during 2018-2020. We note that Br exists primarily as Br where I was present as iodide (I), iodate (IO) and organic I. The median Br concentration was 62 μg/L and 97 μg/L in surface and groundwater respectively. The current study showed that weekly or monthly variations in bromide concentrations regularly occur within any given source water. However, there is no apparent systematic nationwide-long term increase of bromide concentrations in DWTP source waters. For iodide occurrence in raw/untreated drinking waters and wastewater treatment plant effluents, samples contained either iodide or iodate, and only 15% of the samples where their co-occurrence exists contained both of these inorganic species. Iodide was detected in 46% of surface waters and 64% of groundwater at or above the detection limit of 1 µg/L. Iodate ion was widely detected in surface and groundwater. The 75th percentile concentrations of iodide and iodate were 5 and 3 µg/L, but maximum concentrations reached 252 and 145 µg/L, respectively. Interestingly, groundwater had inorganic forms of I i.e. I and IO, whereas, organic I was the dominant specie of I in surface waters. The median Br/I ratio was 20 μg/μg and 17 μg/μg. Furthermore, this talk will discuss the co-occurrence, and speciation of Br and I in drinking water sources for future Br-/I-DBP studies at DWTPs; and implications for DBP regulations based on this nationwide occurrence study.
<b>Bromide and Iodide occurrence in drinking water sources.</b><br /> Bromide ion values shown are median (range) in µg/L; Iodide ion values shown are 75<sup>th</sup> percentile (range) in µg/L.

Bromide and Iodide occurrence in drinking water sources.
Bromide ion values shown are median (range) in µg/L; Iodide ion values shown are 75th percentile (range) in µg/L.


Sunday
Modeling the transport of disinfection byproducts in forward osmosis membrane process
11:05am - 11:25am USA / Canada - Eastern - August 22, 2021 | Room: B401
Ning Dai, Presenter, University at Buffalo; Jiale Xu; Haiqing Lin; Thien Tran
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Forward osmosis (FO) is a new membrane technology with lower energy cost and less irreversible fouling than reverse osmosis (RO). Therefore, FO is being considered as an alternative or supplement to RO for wastewater recycling. However, the performance of FO in removing the disinfection byproducts (DBPs) formed during disinfection of the membrane feed has not been studied. We first evaluated DBP rejection using clean and fouled commercial FO membranes. The FO rejection of N-nitrosodimethylamine (NDMA) and haloacetonitriles (HANs), two high priority (groups of) DBPs, was 31%–76%, higher than that reported in RO. Organic fouling generated by model polysaccharide and protein lowered DBP rejection. Comparison showed that aquaporin membrane exhibited higher rejection than cellulose triacetate membrane for all DBPs in both clean and fouled situations. Subsequently, the effects of reverse salt flux, a unique phenomenon in FO, on DBP transport was evaluated. Reverse salt flux refers to the transport of draw solutes from the saline solution to the feed solution (i.e., wastewater). It was found to hinder DBP transport. Two mechanisms were identified experimentally: the steric hindrance in the active layer caused by the occupation of free volume by draw solutes and the retarded diffusion of DBPs in the support layer via a “salting-out” effect. To enable the prediction of DBP rejection in FO, a modified solution-diffusion model was developed to incorporate these two mechanisms, using a decreased membrane pore radius for the steric hindrance and the Setschenow constant for the “salting-out” effect. Compared with current models, the modified model showed improved prediction for the transport of halogenated DBPs in FO.
Sunday
Emerging unregulated disinfection by-products: Can Brita filters remove them?
11:25am - 11:45am USA / Canada - Eastern - August 22, 2021 | Room: B401
Ashley Perkins, Presenter; Amy Cuthbertson; Susan Richardson, University of South Carolina
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Granular activated carbon was recently shown to effectively remove natural organic matter (NOM) precursor material and lower the formation of regulated and unregulated disinfection by products (DBPs) at full-scale drinking water treatment plants.1 However, it is currently unknown whether point-of-use (POU) activated carbon (AC) filters remove a broad range of regulated and unregulated DBPs formed in treated drinking water. In this study, the efficiency of a Brita® pitcher filter was investigated for removing 57 priority unregulated DBPs from tap water, including halonitromethanes, haloacetamides, haloacetonitriles, haloacetaldehydes, and iodo-acetic acids. A highly sensitive gas chromatography (GC)-mass spectrometry (MS) method was used to measure them.2 To simulate realistic use, Brita® pitcher filters were tested at various ages (at the beginning, middle, and end of their lifetimes) for samples of unspiked tap water and samples of nanopure water spiked with a high and low concentration of DBPs; all experiments were conducted in triplicate. Results demonstrate that DBPs in every investigated class show significant reduction at the beginning of the filter’s lifetime, with a drop in efficiency as the lifetime of the filter progresses. For example, for the high spike level, the Brita filter achieved 64%, 40%, and 33% removal from the beginning (2L), middle (45L), and end (90L) of their lifetimes, respectively. Interestingly, at the end of the filter’s lifetime, concentrations for some DBP classes increase, likely due to breakthrough from the AC column. This project gives us a better understanding of the impact that home-use activated carbon filters have reducing exposure to DBPs from drinking water.
Sunday
Formation, fate and transformation of nitromethanes during wastewater reuse processes
11:45am - 12:05pm USA / Canada - Eastern - August 22, 2021 | Room: B401
JIAMING SHI, Presenter, University of Southern California; Daniel McCurry
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Water resources have become increasingly scarce due to climate change and intensive consumption. Potable reuse of wastewater has been considered a potential solution because water reuse can expand the water resource portfolio. Hence, increasing numbers of full-scale and pilot-scale reuse plants are currently in use or under construction around the world. We recently demonstrated that ozonation of N-methylamine present in wastewater effluent leads to nitromethane formation, and the majority of chloropicrin formed during downstream disinfection can be attributed to nitromethane. In order to produce high quality water, advanced treatment processes such as reverse osmosis, ultraviolet light/advanced oxidation process, and ozone/biological activated carbon are implemented in wastewater reuse treatment trains. The removal efficiency of nitromethane to these subsequent advanced treatments is unknown and we suspected nitromethane might be resistant to these advanced treatment processes because of its polarity and size.
In this work, water samples were collected from different reuse plants employing ozone. We found that nitromethane is not sufficiently removed by RO and UV/AOP with H2O2 failed to decrease nitromethane concentrations, and in some case increased nitromethane concentration. The reasons behind poor removal by RO and AOP were investigated at bench scale. In contrast, BAC removed most nitromethane formed by ozone. In all cases, chloropicrin is detectable during secondary disinfection with chlorine. Even though chlorination of nitromethane is well studied, chloramine is often used instead for secondary disinfection. The kinetic of chloramination of nitromethane remains unclear which lead us to further investigate. The reaction is unique due to nitromethane being a weak carbonic acid. For chlorination, the rate limiting step is the deprotonation step. Chloramine is a weaker chlorinating reagent and a good nucleophile, all of which can alternate the reaction mechanism. A transition of the rate limiting step with respect to pH is expected. Besides, chloramine is the combination of monochloramine and dichloramine who have very different reactivity. By measuring observed rate constant at different pH, kinetic model can be built to determine the different rate constants for all the reaction that happen in this very complex system. This can be used as the guideline for future application on minimizing halonitromethane formation upon secondary disinfection.

Sunday
Halogenation of parabens to form trihalomethanes: Implications for greywater reuse
12:05pm - 12:25pm USA / Canada - Eastern - August 22, 2021 | Room: B401
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid
Para-hydroxybenzoate esters (parabens) are common preservatives in consumer care products, which are mildly endocrine disrupting and have been tentatively associated with certain cancers. In keeping with their widespread use, individual parabens (typically the methyl through butyl esters) have been observed at low-to-mid µg/L concentrations in greywater and high ng/L concentrations in sewage. Parabens are not well-removed by physical treatment, but can be quickly oxidized by e.g., chlorine or ozone. Halogenation of parabens by chlorine and bromine has been studied in the past, and the rapid formation of haloparaben products has been observed, with halogenation patterns reflecting the textbook halogenation of substituted phenols (i.e., 2,6-dihalogenation due to ortho/para direction from the phenolate oxygen, followed by 3,5-dihalogenation due to weak ortho/para direction from halogens). However, all studies to date have generally presumed these haloparabens to be the final product of paraben halogenation, despite rich environmental chemistry literature on the subsequent transformation of halophenols, gained from the study of trihalomethane (THM) formation from model compounds approximating natural organic matter. In this work, we find that in the presence of excess chlorine or bromine, haloparabens are not final products, but rather semi-stable intermediates toward trihalomethanes. THM molar yields of up to ~30% are observed, with highest yields favored by bromination and by mildly alkaline pH, as expected between the pKa values of hypohalous acids and phenols. THM yields of up to ~1500 µg/L were observed from chlorination of simulated greywater produced by mixing paraben-containing consumer care products with Los Angeles tap water at realistic ratios reflecting typical face and hand washing practice. Ongoing work is aimed quantifying the contribution of parabens to the THM precursor pool in real greywaters sampled from greywater reuse sites in Los Angeles, and on quantifying the kinetics of paraben chlorination by chloramines
Sunday
Closing Remarks
12:25pm - 12:30pm USA / Canada - Eastern - August 22, 2021 | Room: B401
Division: [ENVR] Division of Environmental Chemistry
Session Type: Oral - Hybrid

Colloidal nano- and materials intended for biological applications:
10:30am - 12:10pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Neus Feliu Torres, Organizer, Hamburg University; Wolfgang Parak, Organizer, Universitaet Hamburg; Nicholas C. Fitzkee, Ph.D., Presider, Mississippi State University
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Division/Committee: [COLL] Division of Colloid & Surface Chemistry

There are many reports of (potential) applications of colloids in biology/medicine. Classically emphasis is given on one property, originating from homogeneous particles. However, colloids in the context of biology are hybrid materials, for example by modification of the particle by adsorbed proteins, which forms together a new hybrid particle. Colloids also can be intentionally made by different compounds, allowing for multi-functionality. Such assemblies however do not need to be stable, as (intracellular) degradation processes may change the composition of the hybrid particle over time. In this symposium emphasis will be given on the hybrid nature of colloids. Appropriate topics include, but are not limited to: • Synthesis of hybrid particles • Self assembly of particle particle complexes • Analysis methods to characterize hybrid particles • Protein corona formation • Particle degradation • Multi-functionality of particles for imaging, treatment, diagnosis, etc.

Sunday
Withdrawn
10:30am - 10:50am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual

Sunday
Intermolecular binding within the electrochemical double layer on iron oxide nanoparticles: Effect of potential
10:50am - 11:10am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Sebastian Schwaminger, Presenter, Massachusetts Institute of Technology; Alan Hatton
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Pharmaceuticals for cancer therapies and other diseases are very expensive since the production of therapeutic molecules, such as antibodies, is costly and each production process needs to be developed individually. In particular, purification processes, which generally make up to 80-90% of the production train, need to be improved or new concepts need to be developed. Short peptide sequences, so called “tags”, can be used to create new purification strategies based on biomolecular recognition of these sequences. Magnetic iron oxide nanoparticles are an interesting counterpart for peptide tags as their properties facilitate easy handling and manipulation. The key to the design of high-affinity peptide tags lies in an in-depth understanding of surface-peptide recognition patterns. We have developed such a magnetite-binding peptide tag which allows the purification of tagged model proteins from fermentation broths by changing the environment afforded by the surrounding media. However, such pH and buffer switches might also alter the properties of pharmaceutically relevant proteins such as antibodies. We show that the interactions between the particles and the proteins can be modulated by an applied electrical potential which causes changes in the electrochemical double layer; such a process may make it unnecessary to use chemical switching for control of the protein capture.
The iron oxide nanoparticles have been well-characterized by spectroscopy, microscopy and diffraction. The binding affinity between the proteins and the particles was investigated by cyclic voltammetry and impedance spectroscopy of immobilized iron oxide nanoparticles on carbon-based electrodes. The change in the particle properties was monitored by electron microscopy and infrared spectroscopy. The binding and release of biomolecules was studied with UV-Vis spectroscopy.
The process entails the magnetically facilitated separation of biomolecules and their elution based on changes in molecule-particle interactions with electric fields. The study of this system will help to understand the binding of proteins to iron oxide nanoparticles and the formation of an electrochemical double layer under external fields. The electrical double layer formation is not only interesting in biotechnological processes but also in electrochemical catalysis and energy storage. The principles developed here could pave the way to new approaches in biomolecule recognition, protein detection and purification.

Sunday
Strategies to improve cell absorption rate: Precise targeting, dual visualization guided, multiple stimulus responsive liposomes for cancer treatment
11:10am - 11:30am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Cancer is a serious challenge to human health, but the current clinical efficacy is far from expected. As the fundamental to improve cancer efficacy is to increase tumor drug concentration and cellular uptake. This article proposes a liposome strategy (GFC) with active targeting, MR-FRET guidance, and multiple stimulus cumulative response capabilities. The liposome can increase the carrier concentration around solid tumors through active targeting and guide exogenous stimulation with magnetic resonance and fluorescence imaging, thereby promoting the dissociation of liposomes through precise, timely, and cumulative stimulation. This strategy highlights the advantages of accumulating multiple stimuli at the same chemical site and the spontaneous membrane fusion characteristics of the incompletely dissociated liposomes. In general, the targeted aggregation D@GFC liposomes can be dissociated most effectively, and according to the dissociation state of the liposomes, it can optimize the cell uptake scheme by active endocytosis, spontaneous membrane fusion, and drug diffusion. Herein, by gradually increasing the stimulus intensity, the pH-based photodissociation ability of the co-assembled GFC liposomes was first verified by UV and fluorescence spectroscopy. Secondly, combining DLS, TEM, and CLSM, we speculate that liposomes may have dissociation-fusion-recombination-fragmentation behavior during dissociation. Subsequently, cytotoxicity, CLSM, and flow cytometric analysis verified that GFC liposomes could fuse with cell membranes after triggering the dissociation state. In vivo and in vitro imaging of mice showed that the relaxation time of GFC liposomes was 3.08 times higher than that of Gd-DTPA, and the tumor had the highest liposome aggregation after 180 min of injection, which verified the targeting ability and the MR-FRET imaging capabilities of GFC liposomes. In addition, tumor treatment experiments show that the tumors of the D@GFC UV group are 9.13 times smaller than those of the PBS group, which has the best inhibitory effect and again emphasizes the advantages of targeted, visual guidance, and cumulative stimulation strategies.

Sunday
Tuning carbon nanodots and its hybrids for cellular uptake and the oxidative stress effect
11:30am - 11:50am USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Jianjun Wei, Presenter; Zuowei Ji; Anitha Jayapalan, University of North Carolina at Greensboro
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual
Carbon nanodots (CNDs) have attracted tremendous attention since their discovery in 2004 because of their superior water solubility, biocompatibility, photoluminescence, and opto-electronic properties. As such, CNDs have been reported potentially for broad applications in biomedicine, i.e. bioimaging, biosensor, and drug delivery systems. It becomes essential to investigate the activities of CNDs in biological systems by tuning the functionalities of CNDs including compositions, surface groups and charges, etc. Specifically, this work reports some recent findings of how the structures and functions of CNDs influence the cellular uptake, subcellular location and oxidative stress effect in terms of the regulating the reactive oxygen species (ROS) in living cells. We designed and synthesized a series of CNDs from selected precursor molecules by doping different elements (e.g. nitrogen and sulfur) and the hybrids with metal oxides such as core-shell nanoparticles thus tuning their functionalities. Both the N-doped and N,S-doped CNDs demonstrate strong antioxidant capacity by scavenging free radicals in physicochemical testing, however they show opposite effect in two cell lines, EA.hy926 and A549 cells. The N-doped CNDs offer high biocompatibility as an antioxidant by scavenging ROS in the cells, while the N,S-CNDs present strong prooxidant effect by stimulating higher level ROS generation. The cellular uptake and cellular imaging studies of the CNDs in the cells indicate both CNDs mostly target the mitochondria and evidence suggests that sulfur-functionalized CNDs interfere with the electron transport chain in the mitochondrial membrane. Additionally, the hybrid core-shell CNDs@Co3O4 demonstrate different behavior in cellular uptake, cytotoxicity and ROS generation in cells. These results provide evidence that tuning structure-functions of the nanoengineered CNDs is imperative to facilitate the progress for their biomedical applications.
Sunday
Withdrawn
11:50am - 12:10pm USA / Canada - Eastern - August 22, 2021 | Room: Zoom Room 27
Division: [COLL] Division of Colloid & Surface Chemistry
Session Type: Oral - Virtual