Carmofur, also known as 1-hexylcarbanoyl 5-fluorouracil (HCFU) is a drug for colorectal cancer and has been in use for over four decades in Japan, China, Korea and Finland. In addition to colorectal cancer, it has been found effective against other cancers such as head and neck, breast, pancreatic, gastrointestinal, and solid tumors of the brain. Several recent studies also found carmofur beneficial against the novel coronavirus disease 2019, Krabbe disease, and lipopolysaccharide-induced acute lung injury etc. To date, carmofur does not have any LC-MS/MS or MALDI-MS based method for quantitative or qualitative bioanalysis to support further pre-clinical and clinical trials. Herein, we worked on developing and validating tandem mass spectrometric methods for analyzing carmofur and its active metabolite 5-fluorouracil in mouse plasma and other tissues such as brain, kidney and liver. Qualitative analysis was performed by MALDI imaging MS on cryo-sliced brain tissue sections using Shimadzu MALDI 7090 TOF/TOF MS instrument with negative ionization in reflectron mode. Collected MS data was analyzed using IonView software to generate images of the analytes in the brain tissue. Quantitative analysis was performed on Shimadzu LCMS 8040 triple quadrupole mass spectrometer. Carmofur was administered at a dose of 10 mg/kg intraperitoneally. Plasma and other tissues were collected over a period of 4 hours. Collected samples underwent liquid-liquid extraction and the extracted analytes were ionized by negative electrospray ionization and the quantification was achieved in multiple reaction monitoring (MRM) mode with transitions m/z 256.25 to m/z 129.00 for carmofur, m/z 129.15 to m/z 42.00 for 5-fluorouracil. Three quality control samples (low/medium/high) showed acceptable recovery, matrix effect, accuracy, precision, and stability. Finally, we tested the applicability of our method in female Swiss Webster mice for a pharmacokinetic and drug distribution study.

Qualitative and quantitative bioanalysis of carmofur and 5-fluorouracil using tandem mass spectrometry

Chemistry is all about understanding and controlling the properties of matter -- Where are the electrons? How do particular arrangements of atoms and bonds result in the zoo of behaviors known in matter? What new properties can be created by arranging atoms in unnatural configurations? Today, there are about 50 million known chemical compounds. Where and how will the next billion be discovered, and what new properties will they have? In this talk, I will highlight the progress being made to address these questions, with a particular focus on quantum materials. Quantum mechanics is essential to understand individual atoms. Yet, in many cases, it is not necessary to treat the entire system quantum mechanically – quantum mechanics need only be considered locally, while the collective properties of a large collection of atoms adopts behavior describable with classical models. But this is not true in all cases – in some compounds, so-called quantum materials, the observed behavior defies classical models and requires a full quantum mechanical description – that is, the quantum behavior is ‘writ large’ across macroscopic length scales. Perhaps the most well-known example is that of a superconductor – a material that, below a critical temperature called Tc, has zero DC resistance and exhibits a distinct phenomenon known as the Meissner effect – behaviors arising from a collective phase coherence of the electron wavefunction. There are many more – the last 30 years has seen the discovery other macroscopic quantum phenomena. I will give examples of recent advances and discoveries of quantum materials that have implications ranging from sustainable energy to information technology, and also more recent connections to the rapidly growing area of quantum information science and engineering. I will provide a perspective on how tools of chemistry – especially those related to understanding bonding and the motion of nuclei and electrons – can be applied to make further advances in these areas.

Quantum materials

In recent years, we have witnessed the world's condition shift dramatically and remain unpredictable as a result of the COVID-19 epidemic. The covid-19 circumstance had put a lot of strain on the human person, as they were faced with various negative things among close friends and family members as a sort of mortality. During the first wave of COVID-19 and lockdown circumstances, few individuals ventured outdoors to engage in other activities, but during the second wave, everyone was terrified and stayed inside their homes. During the previous two years, everyone took the necessary measures such as wearing masks, using sanitizer, and following other safety standards. The level of radiation indoors is greater than the level of radiation outside. UNSCEAR reported an indoor/outdoor radiation ratio of 1.4. Based on these and a few other studies, it is confirmed that indoor radiation has a greater impact on humans than outside radiation. Furthermore, cancer cases are still rising globally, and cancer mortality rates are greater than COVID-19 mortality rates. Depending on the scenario of the previous two years, it is vital to regularly monitor the relation between cancer patients and indoor radiation levels. Apart from radiation, air may also have an impact on one's health since, for the last two years, everyone has worn a mask. If everyone stops wearing masks, dust and other pollutant gases with tiny contaminants may have an impact on one's health. These two aspects need to be investigated in the upcoming days in order for human beings to live a better and safer existence for the sake of sustainability.

Human health during COVID-19 scenario based on atmospheric radiation and air

The role of interdiffusion between roads and layers during direct ink writing of thermosetting resins is key to good mechanical performance of the resulting parts and components. While a large body of work has been published about the optimization of rheology, printability and print parameters to optimize the bonding between roads and layers, there is very little known about the micro and nanostructure within the roads and at the interfaces between roads and layers. We use microbeam wide angle and small angle X-ray fly-scanning to obtain micron scale resolution of the atomic and nanoscale structure of the constituents in the ink formulation such as inorganic rheology modifiers. The results from these spatially resolved synchrotron scattering studies demonstrate a rich and complex convolution of printing direction, nanoparticle alignment and gradients that result from the highly non-equilibrium process. These results shed light into the often-non-intuitive mechanical performance of 3D printed thermosetting composites and help in the design of better nozzle with optimized geometries.

Rich, complex and spatially resolved alignment of rheology modifier in 3D-printed thermoset nanocomposites via synchrotron microbeam scanning

A Kitaev quantum spin liquid is a state expected to appear in magnetic honeycomb lattices when the Heisenberg exchange interaction is minimized. Traditionally looked at in low-spin d5 magnets, recent theory and experiments have demonstrated that high-spin d7 systems are also promising, with candidates including Na3Co2SbO6, Li3Co2SbO6, and Na2Co2TeO6. Here, we report the synthesis and characterization of hydrated and dehydrated versions of a mixed alkali metal cobalt honeycomb. The mixture of alkali metals and variation in hydration level are impacting the Kitaev physics observed by changing the strength of the nearest neighbor magnetic interactions. Both the hydrated and dehydrated versions of NaKCo2TeO6 demonstrate antiferromagnetic (AFM) ordering at ~17 K and ~14 K, respectively. TGA/DSC and XRD confirms the presence of about 0.5 moles of H2O within the hydrated version. We will report on our attempts to connect the structural changes to the underlying Kitaev physics.

Synthesis of hydrated and dehydrated layered Kitaev magnets

In the Sigma Pi Chemistry club, we believe that as chemists, we have a duty to do our part to serve the community and protect the environment. One of the ways that our ACS chapter does this is through a bi-annual “Highway Clean-Up” event. In 1998, Sigma Pi adopted a section of a local highway from the Texas Department of Transportation and has since gone back every semester with a group of our members to clean up the litter and other discarded items in the area. This event typically starts with the volunteers arriving at the university for a light breakfast, during which the organization officers give a safety briefing and hand out gloves, vests, and trash bags to all of the participants. Next, the group is divided into teams and we begin cleaning the highway. The event usually ends with a group picture and everyone going about the rest of the day. This event gives individuals a better perspective on the environmental impact one’s actions can have— even with something as seemingly meaningless as littering. For Earth Day 2021, our student chapter celebrated Earth Day with our annual “Tie-Dye with Sigma Pi” event. During this event, our members were given a brief lecture on different dyes and pigments that occur in nature and are also given the opportunity to use various dyes prepared by the organization’s officers to tie-dye anything ranging from t-shirts to socks and even lab coats. These dyes were made from various fruits, vegetables, and spices. Much of the produce used to make the dyes had anthocyanin pigments, which change color depending on the pH. So we used baking soda and vinegar to achieve the colors that we wanted. Members usually enjoy this activity because it presents “green chemistry” in a way that is very tangible to them. It is typically a really popular event, and as such it has become one of the main events in our chapter. For the next Earth Day, our chapter will be setting up a booth at our campus’ student union building from about 11:00 am to 1:00 pm. We plan to educate the students on campus on how they can efficiently recycle through a demonstration. We also plan to pass out liquid nitrogen soda slushies while people are watching our green-living demonstration.

Sigma Pi goes green: The UMHB chemistry club protects the environment

Incorporation of V(V) clusters into polymer hydrogels has been used to impart photo-responsive behavior and this results in tuning of the properties of the hydrogel during light irradiation. To define the photochemistry in these systems, V(V) coordinated to simple hydroxy acids (tartrates) was used to represent polyoxovanadates. The photochemistry was studied using Ultraviolet visible spectrometry, X–ray crystallography, gas chromatography, FTIR and electron paramagnetic resonance (EPR) spectroscopy. Irradiation at 365 nm caused the V(V) tartrate to change from yellow through green to brownish purple, developing a characteristic three–band absorption spectrum with maxima corresponding to a V(IV) photoproduct. EPR spectroscopy confirmed a reduction from diamagnetic V(V) to paramagnetic V(IV) taking place with the growth of an 8-line V(IV) hyperfine pattern over time. Inspired by these findings we have now developed interesting macroscopic effects in cellulose-agarose hydrogels with the light responsive properties of vanadium. A concomitant oxidative decarboxylation of the polysaccharide was noticeable upon the reduction of V(V) to V(IV). This reduction of the metal ion and possible breakdown of polysaccharide chain induce irreversible changes in the microstructure of the hydrogel which enables the controlled delivery of V(IV) and possibly an encapsulated cargo. A significant drop in hydrogel properties like storage and loss modulus, viscosity drop in polymer solution and increase in pore sizes were observed through irradiation. Interestingly, a photomask can be used to create discrete patterns on these materials upon irradiation. We now expect to develop exciting macroscopic effects with the light responsive properties of vanadium in polysaccharide-based materials.

Photochemistry of vanadium clusters and applications for responsive materials

To monitor the viscosity in situ of polymers in real-time remains a challenge as traditional rheological methods can’t be utilized in confined environments. In this study, [Cu(I)(diptmp)2]+ (diptmp = 2,9-diisopropyl-2,4,7,8-tetramethyl-1,10-phenanthroline) was incorporated into industrial adhesives as an optical probe. The luminescence of the [Cu(I)(diptmp)2]+ was monitored during the curing process (viscosity increases) for real time sensing of viscosity via changes in luminescence. [Cu(I)(diptmp)2] in epoxy glue showed increased emission lifetime of the triplet metal to ligand charge transfer (3MLCT) state in real-time as the glue was cured. Monitoring the real time viscosity by swelling (viscosity and lifetime decrease) and by unswelling (viscosity and lifetime increase) of the polymer film was also performed to verify the reversibility and absence of initiator chemical quenching. Viscosity in opaque samples was also measured which showed a similar correlation of increased luminescence lifetime as the viscosity increase during curing of the adhesive. [Ru(II)(bpy)3]2+ (bpy = bipyridine) as a control was used to monitor lifetime changes showing that the [Cu(I)(diptmp)2]+ optical probe had higher emission lifetimes and was more ubiquitous as a real-time viscosity sensor in a variety of systems. These results highlight how the [Cu(I)(diptmp)2]+ optical probe can be used to sense small viscosity changes, including those that are unable to be detected using traditional polymer characterization methods such as rheology.

Real-time viscosity monitoring using luminescent Cu(I) phenanthroline complex: Applications in inorganic sensors

A class of wide bandgap van der Waals materials termed II-VI layered hybrids (II-VI LHs) are capable of broad-band white light-emission and possess potentially high charge carrier mobility. However, only the properties of the bulk (non-exfoliated) material have been studied; their few- or single-layer counterparts remain unexamined by experiment. We demonstrate the exfoliation of two of LHs, ZnSe(ba) (ba = n-butylamine) and ZnSe(oa) (oa = n-octylamine) by shear mixing for the first time, and the results show that shear exfoliation can produce II-VI LH dispersions having concentrations comparable to those achievable with shear-exfoliated graphene. Casting on substrates reveals shear-thinned sheets, the thinnest of which have thicknesses of just 4 nm, corresponding to bilayer ZnSe(alkylamine). However, structural rearrangement and chemical degradation occur during exfoliation, and our experimental results support that shear rate, exfoliation solvent, alkylamine identity, and environmental exposure all play important roles in the stability of these materials. To develop a better understanding of how ligand identity influences the degradation rate, a series of ZnSe(alkylamine) lamellar hybrids are successfully synthesized by ligand metathesis. Analysis by diffuse reflectance spectroscopy and contact angle measurements show that degradation rate is inversely related to ligand length. Metathesis with cyclic and heteroatom ligands show that hydrophilicity also plays a role in the stabilization of this class of materials. Exposure to isotopically enriched water and dioxygen and subsequent analysis by dynamic secondary ion mass spectrometry shows that both water and dioxygen are chemical reactants in the LH degradation process. A water-initiated degradation pathway is proposed and is supported by density functional theory (DFT) calculations.

Dimensional reduction and chemical stability of a series of ZnSe-based layered hybrid semiconductors

Thermosets printed using additive manufacturing (AM) technologies are often brittle, often making the resulting polymers unsuitable for use within structural applications or as end-use products. Secondary phase toughening via liquid rubber modification is a common toughening method that has previously been established for use in traditional, thermally cured thermosets. However, this toughening technique has yet to be explored for use within thermosetting photolithography resins. Though the fracture toughness (KQ) of modified thermosets was increased from 0.48 ± 0.01 MPa*m1/2 to 0.82 ± 0.15 MPa*m1/2 when 20 phr of the liquid rubber was incorporated into the resin, both glass-transition temperature and flexural strength were reduced. To supplement this loss in material performance, silica nanoparticles were added into the system as well. Resulting hybrid materials were successfully printed using digital light processing vat photopolymerization. It was found that both thermal and mechanical properties were improved by the presence of the nanoparticles. When used together, a synergistic toughening effect was observed as well.

Additive manufacturing of toughened polymer-Matrix composites using hybrid resin systems

High entropy materials, multicomponent systems with a high configurational entropy term, i.e., a large positive ΔS due to compositional disorder, have received an explosion of interest in the recent years due to the impact the disorder can have on the properties, an example seen in Ni super-alloys and coatings to protect from corrosion. In the area of high entropy oxides (HEO), in particular systems with multiple components on the cation sublattice, there is intriguing questions regarding the presence of the local order/disorder in accordance with the single-phase structure present in these ceramics. The perovskite structure serves as an attractive target thanks to structural distortions it undergoes to adopt a wide range of cations in the lattice. Bulk single crystals are essential in these studies to allow for more characterization tools in both crystal structure and magnetism. We report the first synthesis of bulk single crystals of HEO perovskite SmFe0.25Ni0.25Cr0.25Co0.25O3 using a laser diode floating zone furnace. Characterization by single crystal x-ray diffraction supports the previously reported space group Pnma. Magnetization measurements match reported powder data showing a downturn at temperatures below T=15 K. Further work on directional magnetization as well as heat capacity measurements to better understand the magnetic behavior going in the disordered transition metal sublattice will be reported. Expanding this to single crystals of the other rare-earth HEO perovskites, along with potential charge doping using atoms such as Sr, will give us a better understanding of high entropy oxides and their local magnetic order/disorder.

Transition metal (dis)order in single crystal rare earth high entropy perovskites

3D printing has advanced greatly with regards to producing highly elaborate and delicate structures revealing superior mechanical strength and dimensional stability in a high throughput manner. The overall mechanical properties of printed materials, particularly high performance polymeric materials, are highly dependent on the morphological characteristics generated during the whole 3D printing process. For semi-crystalline polymers, the printing parameters directly impact key morphological aspects such as crystallization kinetics, crystal orientation, crystallinity, and phase-separated (or self-assembled) morphological features. For this study, we perform in-situ synchrotron small- and wide-angle X-ray scatterings on a semi-crystalline engineering thermoplastic to monitor the evolution of morphological features in real time. Since the degree of supercooling, polymer-substrate interface, and polymer-air interface are considered as key parameters inevitably involved in the 3D printing process, we attempted to correlate their roles to the resulting morphological characteristics as well as the resulting quality of the printed material that is evaluated in terms of mechanical properties.

In-situ synchrotron X-ray scattering studies on morphological evolution of semi-crystalline polymer during 3D printing process

Global anthropogenic pollution has caused great damage to the soil ecosystem. Chemical metallic agents, such as heavy metals, at low concentration, cause soil contamination. Most food products are often contaminated due to soil unsuitability, making them harmful to human health. Plants have phytoextraction capacity, so they are used to promote soil decontamination. To accelerate this process, bacteria are added and used to promote a further increase in the plant's absorption capacity. The main objective of our research is to determine the effect of Pseudomonas fluorescens on the phytoremediation process of heavy metals by Sida rhombifolia L. We propose to use Pseudomonas fluorescens to accelerate the phytoremediation process of Sida rhombifolia L. This is a wild plant that can adapt to any type of soil in the tropical and subtropical zone. The specific objectives to achieve our goal are 1) to determine the presence of Pseudomonas fluorescens in agricultural soil by bacterial microbiology analysis and 2) to identify the presence of chromium (Cr) by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) techniques. For this purpose, a group of Sida rhombifolia L. species were planted in agricultural areas located on the west coast of Puerto Rico. In the analysis of bacterial microbiology, Brain Heart Infusion Agar (BHIA) and Nutrient Agar (NA) were used for bacterial culture to observe which culture medium was more efficient and to observe the growth of colonies to subsequently identify Pseudomonas fluorescens in the soil. After colony formation, biochemical tests are performed to identify Pseudomonas fluorescens. A large amount of bacterial flora was detected at a depth of 3 inches, in which we will identify the presence of Pseudomonas fluorescens and Cr, wil be detected at a depth of 3 to 8 inches, in the soil.

Detection of Pseudomonas fluorescens and heavy metals as potential factors of efficiency in a phytoremediation process of Sida rhombifolia L

Polybenzoxazine are a thermosetting polymer that have superior properties to traditional phenolic resins, including near zero volume shrinkage during cure, high glass transition temperature (Tg) and elevated char yields. These enhanced properties make polybenzoxazine exciting candidates as the polymer precursor for carbon-carbon composites (CCC). The main challenge in fabricating carbon-carbon composites is the cost to manufacture them on a large scale. Increasing the amount of carbon deposited (char yield) and understanding any volume change the matrix experiences during pyrolysis is of critical importance in addressing these processing challenges. Benzoxazine monomers using different phenolic derivatives and either furfurylamine or aniline as the primary amine were synthesized and pyrolyzed to form carbon. The furfurylamine-based benzoxazines had increased Tg and char yield compared to the aniline-based benzoxazines. In regard to the carbon, higher final char yields resulted in carbons that experienced volume shrinkage (negative volume change) as opposed to volume expansion (positive volume change). This study shows that furfurylamine-based benzoxazines outperform aniline-based benzoxazine when looking at important properties for the polymer precursor of carbon matrix. Furthermore, principles that can predict matrix volume change solely from the carbonization reaction of the polymer precursor were presented. These principles may lead to the design of more efficient polymer precursors as the carbon matrix for carbon/carbon composites.

Investigation between carbon ofrmation and polymer precursor for aniline-based and furfurylamine-based polybenzoxazines

Electrical discharges in gases that operate near room temperature and at atmospheric pressure can be interfaced with aqueous solutions to serve as a gaseous, metal-free electrode and mediate electrochemical reactions. In particular, the injection of gas-phase electrons into solution to generate solvated electrons, one of the strongest chemical reducing species, has been demonstrated, and applied to the synthesis of metal nanoparticles, the electroreduction of carbon dioxide to oxygenates, and the electroreduction of molecular nitrogen to ammonia. For the most part, these plasma-liquid studies have been limited to water as the solvent. Expanding the solvent system to organics would open up new chemical applications such as small molecule transformations and controlled depolymerization/degradation of engineered plastics. In this work, we investigated two such examples: 1) the conversion of anisole and 2) the degradation/depolymerization of polystyrene (PS) and polyoxymethylene (POM). In order to avoid the need for an electrolyte, the experiments were performed with a remote plasma configuration where the afterglow of the discharge was in contact with the surface of the organic solvent. Following treatment of the solvents containing the precursor, a suite of analytical techniques were used to characterize the products including nuclear magnetic resonance (NMR) spectrometry, high-pressure liquid chromatography (HPLC), gas chromatography mass spectrometry (GC-MS), and liquid chromatography mass spectrometry (LC-MS). We found that anisole was converted to new aromatic compounds. In the case of POM, we found depolymerization at much lower temperature than its thermal degradation temperature to formadehyde, and in the case of PS, there were a wide range of small molecules. These findings suggest that non-thermal plasma can trigger molecular transformation in catalyst free conditions and expand chemical and electrochemical processes involving organic and polymeric molecules.

Plasma electrochemistry for molecular transformation

Wastewater-based epidemiology (WBE) estimates collective consumption or exposure to chemicals or pathogens by tracking the substances excreted in the population's wastewater. This presentation reports three applications of WBE using MS: 1) Detection for small molecules as biomarkers, 2) Detection for large molecules as biomarkers, and 3) Detection of viral proteins of SARS-CoV-2 by High Resolution MS (HR-MS) and MALDI-TOF-MS. The identification of small molecules used as biomarkers is linked to the search of human biomonitoring (HBM) studies . Few examples of non-target analysis are reported here. Proteins can be a good indicator of prevalent diseases in the population and, together with biomarkers composition in sewage, can reflect the surrounding human activities (e.g., industry, agriculture, and pest control) as well as the health status of populations . While biomarkers might be found in the soluble part of the effluent, proteins are likely expected to be also in the particulate matter because they travel in the water media attached to the surface of particles and bacteria. MS approaches based on HR-MS and MALDI–TOF-MS could be feasible for rapid detection and routine monitoring of proteins. By applying HRMS, we demonstrated the presence in urban sewage waters of proteins from diverse origins, including human proteins such as uromodulin, α-amylase, and S100A8, which have been proposed as health markers associated with renal function or stress-related changes. Due to the large number of data recorded, the bioinformatics treatment to recognize the complex pattern of the omics already proposed for small molecules becomes crucial here. In this work, a recent metabolomic mass spectrometry non-target analytical methodology named the Regions of Interest-Multivariate Curve Resolution (ROIMCR)was applied to our proteomics data. . Environmental Proteomics (EP) applied to WBE provides additional information on human protein biomarkers together with characteristic peptides of other species such as rat, mouse, cattle, chicken as well as distinctive peptides of a large number of bacteria. EP-WBE approach can be applied to SARS-CoV-2 proteins and peptides in the coming years, in a similar way it has already been used for clinical samples. EP-WBE is a complementary tool to PCR and follows the concept of “thinking outside the box“ to detect Covid-19 outbreak.

High resolution mass spectrometry in wastewater-based epidemiology (WBE) for the determination of small and large molecules as biomarkers of exposure. Needs for COVID-19 testing with environmental proteomics (EP-WBE)

It was demonstrated in this study that appropriate concentrations of oxalate (Ox) would lead to greatly accelerated electro-generation of Fe2+ but obviously lower power consumption in the Fered-Fenton system. Depending on the Ti electrode with pristine TiO2 layer, effects of important parameters on the SMX degradation were investigated in the Fered-Fenton-Ox system. It was found that the heterogeneous interfacial electrochemically reduction of FeIII was critical in the Fered-Fenton-Ox system relying on the surface hydroxyl bonding FeIII-Ox and formation of Fe-O-Ti bonds. A heterogeneous-homogeneous reaction mechanism was therefore proposed. It included the heterogeneous interfacial electrochemical generation of FeII-Ox and the homogenous Fenton oxidation of pollutants. The promotional role of Ox would be also homogenous and heterogeneous, i.e. maintaining ferric at higher pH and forming specific FeIII-Ox complex as well as accelerating the solid-liquid interfacial heterogeneous iron cycle. Furthermore, a continuous-flow pilot study was conducted in treating a printing and dyeing industrial wastewater. As compared to traditional Fenton and Fered-Fenton systems, the Fered-Fenton-Ox system could achieve more efficient COD removal with a relative low cost/△COD, suggesting great advantages in its practical applications for treating real industrial complex wastewaters.

Synergistic degradation of sulfamethoxazole in an oxalate-enhanced Fered-Fenton system: The critical heterogeneous solid-liquid interfacial mechanism and an insight in practical application

Annealing and layer formation of nanoparticles especially the application of colloidal inks applied to porous materials is crucial for functional coatings and printing. Our goal is to distinguish and quantify the differences in structure formation during annealing of the deposited colloidal inks on a) a porous material and b) a solid non- porous material. Therefore, a layer of cellulose nano fibers (CNFs) – so-called nanopaper – and silicon wafers were used as porous and non-porous materials, respectively. For the layer formation of colloids on top of the CNF thin film, the colloid-CNF and the colloid-colloid interactions in a liquid state play a significant role. To meet this challenge, we used novel colloidal inks consisting of poly-butylmethacrylate (PBMA) and poly-sobrerolmethacrylate (PSobMA) in an aqueous dispersion. These colloidal inks are based on a cationically hydrophilic block chain extended and a hydrophobic block forming core-shell nanoparticles with different morphologies. This provided us with the advantage of tailoring their surface and core chemistry on-demand. To study the real time structural and morphological changes during deposition and annealing process, we utilized grazing incidence small-angle X-ray scattering (GISAXS). In addition, for a better understanding of the drying process, we investigated the interaction between the CNF and colloids in aqueous dispersion by small-angle neutron scattering (SANS). We demonstrate that the colloidal dispersions enter the CNF layer, the mixture of solvent and colloids remain on top of the CNF surface, which leads to a very complex drying and annealing process, and the cationically charged nanolatexes successfully adsorb into cellulose surfaces. In addition, the structure and morphology of both CNF- and colloidal layers can be influenced by exceeding the glass transition temperature of the colloids.

Colloidal layer formation and imbibition of colloidal inks on and in thin cellulose films

An extensive direct dynamics study on the collisions of hyperthermal (14.9 kcal mol-1) atomic oxygen with a variety of graphene surfaces to explore possible reaction channels. Several models, ranging from pristine graphene to graphene with defects and with different extents of oxidation and nitridation, are investigated. The impinging oxygen is found to form various surface oxygenated species, such as epoxides, ethers, and lactones, as well as gaseous species, such as CO, CO2, O2, N2, CN, and NO. Some of the gaseous species have been detected in recent molecular beam studies, and our simulations help to reveal their formation mechanisms. Comparison with previous dynamical studies for a much higher oxygen incident energy (120 kcal mol-1) finds similar reactive channels and reaction mechanisms, with quantitatively different product branching ratios.

Direct dynamics simulations of hyperthermal O(3P) collisions with pristine, defected, oxygenated, and nitridated graphene surfaces

Human urine is one of the common liquid by-product of metabolism in both humans and many other animals. It is a complex solution comprising of water, microbes, organic and inorganic compounds of which the highest constituent are water and urea. The complex nature of urine and its abundance makes it a pollutant and a burden to the environmental soil and water. Its inorganic constituent includes elements such as potassium, sodium, calcium, chloride and sulphate. Although, the organic portion has been used for material synthesis, there is little or no attention on the utilization of these inorganic constituent of urine for material synthesis. Hence, the current investigation is to prepare novel material comprising NaCl, KCl and CaS as a composite nanoparticles from the inorganic salts present in human urine. The antioxidant properties of the material were studied in a 96-well culture plates using dimethyl sulfoxide (DMSO) as the solvent incubated above room temperature. Finally, antibacterial activities of this novel nanoparticle system was studied against selected Gram-positive and Gram-negative bacteria by using both well diffusion and disc diffusion assay. When compared with ascorbic acid, the synthesized nanoparticle was found to possess maximum antioxidant activity. It was also found to be active against the selected bacteria strain with zone of inhibition that is above 10mm in all tested bacteria.

Synthesis, characterization of halite/sylvite/CaS single nanoparticle system from fresh, unfiltered human urine and its biological investigations

Following the discovery that semiconducting oxides such as ZnO and TiO2 can photocatalytically split water, there has been a huge effort to increase the efficiency of the process as a means of harnessing solar energy. Most of this work has involved empirical testing, although there has been a significant amount of surface science aimed at understanding the detailed mechanism. More recently, this has been extended to in-situ measurements at liquid-solid interfaces. This talk will describe our current understanding of the crystallography of the interface between ZnO and TiO2 with liquid electrolytes. Remarkably, these interfaces are characterized by an ordering of the contact layer. For instance, chlorine and hydroxyls are ordered in the contact layers of oxide aqueous interfaces, with implications for the photo-physics and chemistry.

Ordering at metal oxide-aqueous electrolyte light harvesting interfaces

Accurate calculations of free energy differences for isotopic substitutions are essential for environmental and geological chemistry. These and other properties of nuclei in condensed phases are obtained using path-integral molecular dynamics (PIMD) methods. However, previously existing PIMD integrators are plagued with resonance instabilities, requiring equations of motion to be integrated with short timesteps [J. Chem. Phys. 151, 124103 (2019)]. We propose a simple modification to the standard PIMD integrator that removes these issues at no added computational cost. Seemingly counterintuitive, the idea is to replace the exact free ring-polymer sub-step with its Cayley transform approximation. This modified PIMD integrator removes the finite timestep error for local observables in harmonic systems and allows one to take significantly larger timesteps with no loss of accuracy in general systems, as illustrated by the highly anharmonic example of liquid water [J. Chem. Phys. 152, 104102 (2020)]. Use of this improved PIMD integrator yields to date the most accurate free energy differences for isotopic substitutions in condensed phase, validating and improving on the existing experimental calibrations.

Accurate quantum statistics from improved path-integrals in imaginary time

Sodium rare earth fluorides (NaREF4), due to unique luminescent properties, have attracted extensive research on designing and synthesizing NaREF4 materials with diverse compositions and nano structures to expand and optimize their applications. The energetic study of NaREF4 not only facilitates the rational design and manufacture of these materials, but also promotes the understanding of structure–thermodynamics relationships in terms of ionic sizes and structure scales in these systems. With the help of high temperature oxide melt solution calorimetry, formation enthalpies of bulk NaREF4 with varying RE elements are evident. The enthalpic energetic trends indicate most NaREF4 compounds are thermodynamically stable relative to binary fluorides but follow a reverse trend across the lanthanide series compared to many RE oxide compounds. Exothermic formation enthalpies of NaREF4 are larger with smaller RE3+ ions, which is related to the decreasing coordination number of F− around RE3+ in the formation of NaREF4. Energetic studies were carried out in the NaF–NdF3 system to study cubic (α) to hexagonal (β) phase conversions at the nanoscale in aqueous solution. Combing with composition and structure characterizations, a Na deficiency is found resulting in the formation of cubic (α) crystallographic polymorphs at the nucleation stage. While the α → β phase conversion in aqueous solution is associated with compositional variation during the nanocrystal growth, the β → α solid-state phase transformation is driven strictly by temperature for stoichiometric compounds. These energetic assessments of NaREF4 provide new insights into the formation, conversion, and stability of RE fluoride materials, which will inspire more efficient pathways to utilize and recycle RE elements.

Energetic studies of sodium rare earth fluorides from bulk materials to nanocrystals

Advancements in hardware have enabled high-resolution mass spectrometric (MS) detection, increasing confidence in molecular identifications they provide, but also causing new challenges for efficient data management and processing. The current state of the art for two-dimensional gas chromatography (GCxGC) batch non-targeted analysis (NTA) data processing is a two-step process of data exploration followed by retention time and mass spectral refinement to find features of interest across a batch. Difficulty or failure occurs for ~40% of features during this process for two major reasons. First, the mass spectral complexity results in deconvolution errors for low-level features leading to missing peaks or time-consuming manual re-integration. Second, the samples are of sufficient chromatographic complexity that data exploration results in a significant rate of divergent identifications leaving data too complex to be reduced in a reasonable timeframe. Our team overcomes this complexity by combining iterative processing of high-resolution GCxGC-MS data with machine learning (ML) to allow detection of low-level compounds otherwise missed by traditional peak finding algorithms. We leverage the information emergent from the batch to overcome the challenge of relying on peak finding and deconvolution for complex, high-resolution MS data. Our novel methodology finds compounds with an increase in both sensitivity of detection and specificity of identification compared to state-of-the-art commercial software’s peak finding and deconvolution methods. We first apply ML to automatically rank spectral signals into a quality hierarchy from the list of signals identified, by first-pass peak finding. Next, a representative signal is selected according to its quality at each chromatographic retention time in each sample. The high-resolution data is then exploited by identifying the mass spectral fingerprint of each high-quality molecular feature. This mass spectral fingerprint is leveraged in a second iteration of processing to extract quantitative information across the batch of samples by searching for specific ion signatures. Our implemented method enables high-throughput, comprehensive NTA, and keeping up with hardware advances in high resolution GCxGC-MS.

Automated low level signal capture in high resolution GCxGC-MS

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.