Message from Division Chair
Biological, Medical, and Soft Matter Physics session of the ANPA conference, July 24-26, 2026, serves as a premier interdisciplinary forum for exploring the physical foundations of living systems. By merging the mechanical insights of biological physics with the clinical applications of medical physics and the material science of soft matter, this session examines how fundamental principles govern everything from molecular self-assembly to advanced diagnostic imaging and radiation therapies. We invite researchers, clinicians, and theorists to present their latest experimental and computational findings on topics ranging from liquid crystals and polymers to the complex dynamics of cells and tissues. Join us to share your research, foster new collaborations, and push the boundaries of how we understand and treat the human body; we look forward to receiving your abstracts and seeing you at the conference.
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Invited Speaker
Catastrophic Transitions and Seizure Dynamics in the Human Brain: Toward Improved Seizure Localization
Epilepsy is increasingly recognized as a disorder of large-scale brain dynamics rather than a purely focal pathology. Seizures emerge when interactions among neuronal populations drive the brain across critical dynamical transitions that produce abrupt changes in network activity. In this lecture, I will present research from our group aimed at uncovering the dynamical principles underlying seizure generation, propagation, and localization in the human brain. Using extra- and intracranial electrophysiological recordings (EEG, iEEG/sEEG) from patients with drug-resistant epilepsy, we combine tools from nonlinear dynamics, network science, and statistical physics to track seizure-related brain activity. These approaches include Granger causality methods to map directed interactions among brain regions, node volatility to identify dynamically unstable network nodes associated with seizure onset, scale-free spectral analysis to characterize excitation–inhibition imbalance in epileptogenic cortex, and differential phase-space topology revealing catastrophic dynamical ruptures in neural activity. Together, these approaches help identify regions of cortical instability and improve seizure onset localization, which is critical for epilepsy surgery and other treatments. More broadly, this work highlights how nonlinear dynamics and statistical physics can illuminate mechanisms underlying pathological brain activity.
Division Schedule
Please look below for detailed schedule.
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Abstract Number: ANPA2026N00071 Presenting Author: Kamal Khanal Co-Authors: nan Presenter's Affiliation: Tribhuvan University Title: n Silico Study On Structural, Electronic, And Adsorption Properties Of Cisplatin/(tio2)n (n = 2-5) Nanoclusters And Interactions With Hen Egg White Lysozyme Location: In-Person Presentation, CDP Show/Hide Abstract This study explored the structural, adsorption, and electronic properties of titania nanostructures loaded with cisplatin using density functional theory (DFT) at the level of B3LYP/LANL2DZ functional in gas phase, and examined the binding potential of the cis-(TiO2)n (n = 2 - 5) nanoclusters (NCs) with hen egg white lysozyme (HEWL) via molecular docking. Our results revealed that cisplatin adsorption on (TiO2)n NCs yielded adsorption energies of ?56.97, ?53.84, ?48.40, and ?39.23 kcal/mol for cis-(TiO2)2, cis-(TiO2)3, cis-(TiO2)4, and cis-(TiO2)5 NCs, abbreviated as NC1, NC2, NC3, and NC4, respectively. Their interatomic interactions were further evaluated using reduced density gradient (RDG) and quantum theory of atoms in molecules (QTAIM) analyses. Among the studied systems, although NC1 exhibited a less negative adsorption energy compared to the other NCs, it indicated strong surface reactivity. Further, NC1 also showed the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) energy gap of 3.66 eV, suggesting greater charge transfer and reactivity. Additionally, dipole moment, global reactivity descriptors, molecular electrostatic potential (MEP) surface, and natural bond orbital (NBO) results of the NCs were more favorable than those of cisplatin. Based on the DFT results, the protonated NC1, i.e. (TiO2)2H2 was selected for further analysis of its interactions with HEWL. The docking scores of cisplatin, (TiO2)2H2, and cis-(TiO2)2H2 with HEWL were found to be ?4.41, ?3.82, and ?6.74 kcal/mol, respectively, indicating strong binding affinity and therapeutic potential of cis-(TiO2)2H2. More experimental investigations are required to confirm its effectiveness.
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Abstract Number: ANPA2026N00083 Presenting Author: Puspa Kumari Malla Co-Authors: Amba Datt Pant; Hari Shankar Mallik; Akihiro Koda; Katsuhiko Ishida; Burkhard Geil ; Koichiro Shimomura Presenter's Affiliation: Central Department of Physics , Tribhuvan University Title: Study of Defects Iin Ice Using Muon Location: In-Person Presentation, CDP Show/Hide Abstract Proton reorientation and long range proton transport in the hydrogen bond network of ice are mediated by orientational defects, among which Bjerrum L-defects, hydrogen bonds carrying no proton, play a central role [1,2,3]. Probing such defects at the atomic scale requires a sensitive local probe. Since muon (µ+) acts as a sensitive local probe (?µ ? 3.2 ?p), we use it for study of defects dynamics in ice. The muon has two special characteristics - fully spin polarized and asymmetric decay to positron preferentially along the muon-spin direction at the time of decay. In frozen pure water, muon spin rotation, relaxation and resonance (µSR) method precisely measured the structure of water and formation of MuOH [4]. To understand the defect dynamics, we have performed temperature-dependent µSR study in L-defective ice (KOH-doped, 0.1 wt%) at J-PARC, Japan, under zero field and weak transverse fields. We found a clear difference in time spectra observed in pure water and defective water. Experimental results and theoretical works (quantum simulation and DFT calculations) to explain the results will be discussed in the program.
References
[1] J. D. Bernal and R. H. Fowler, J. Chem. Phys. 1 (1933) 515-548.
[2] N. Bjerrum, Science 115 (1952) 385-390.
[3] B. Geil, T. M. Kirschgen and F. Fujara, Phys. Rev. B 72 (2005) 014304.
[4] A. D. Pant et al., Phys. Rev. B 110 (2024) 104104.
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Abstract Number: ANPA2026N00076 Presenting Author: Dhirendra Prasad Upadhyay Co-Authors: Om Jha Presenter's Affiliation: Tri-Chandra Multiple Campus Title: In Silico Study of Natural Compounds Aas Potential URAT1 Inhibitors for the Treatment of Uric Acid Location: In-Person Presentation, CDP Show/Hide Abstract Hyperuricemia is a metabolic disorder caused by elevated serum uric acid levels and is a major risk factor for gout and related complications. Since the human urate transporter 1 (URAT1) reabsorbs nearly 90% of filtered uric acid in the kidneys, it is an important therapeutic target. However, although several URAT1 inhibitors are clinically available, their use is limited by toxicity and adverse effects. Natural products offer a promising source of bioactive compounds for novel drug discovery. This study aimed to identify potential natural URAT1 inhibitors through an in silico study.Bioactivity data for URAT1 inhibitors were collected from the ChEMBL database after applying drug-likeness, PAINS, and Brenk filters. Molecular descriptors were generated using ECFP6 fingerprints, and a Random Forest classifier was developed to distinguish active and inactive compounds. The model achieved strong predictive performance, with a 5-fold cross-validation ROC-AUC of 0.923 ± 0.039, a test ROC-AUC of 0.892, and an MCC of 0.661, indicating reliable classification capability. The optimized model was then applied to virtually screen 715,344 natural compounds from the COCONUT database, identifying top-ranked hits for docking studies. Molecular docking against the URAT1 protein revealed several promising candidates, with CNP0121706.0 and CNP0568038.0 exhibiting the highest binding affinities of ?10.18 kcal/mol and ?10.13 kcal/mol, respectively. Further, RMSD, RMSF, RG, SASA and H-bond analyses using molecular dynamics simulations show both complexes are stable upto 200 ns.
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Abstract Number: ANPA2026N00070 Presenting Author: Mukesh Dhamala (Invited) Co-Authors: nan Presenter's Affiliation: Georgia State University, Atlanta, GA, USA Title: Catastrophic Transitions and Seizure Dynamics in the Human Brain: Toward Improved Seizure Localization Location: In-Person Presentation, Kennesaw Show/Hide Abstract Epilepsy is increasingly recognized as a disorder of large-scale brain dynamics rather than a purely focal pathology. Seizures emerge when interactions among neuronal populations drive the brain across critical dynamical transitions that produce abrupt changes in network activity. In this lecture, I will present research from our group aimed at uncovering the dynamical principles underlying seizure generation, propagation, and localization in the human brain. Using extra- and intracranial electrophysiological recordings (EEG, iEEG/sEEG) from patients with drug-resistant epilepsy, we combine tools from nonlinear dynamics, network science, and statistical physics to track seizure-related brain activity. These approaches include Granger causality methods to map directed interactions among brain regions, node volatility to identify dynamically unstable network nodes associated with seizure onset, scale-free spectral analysis to characterize excitation–inhibition imbalance in epileptogenic cortex, and differential phase-space topology revealing catastrophic dynamical ruptures in neural activity. Together, these approaches help identify regions of cortical instability and improve seizure onset localization, which is critical for epilepsy surgery and other treatments. More broadly, this work highlights how nonlinear dynamics and statistical physics can illuminate mechanisms underlying pathological brain activity.
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Abstract Number: ANPA2026N00077 Presenting Author: Pritom Mukherjee Co-Authors: Pritom Mukherjee; Sydney Apraku; Mukesh Dhamala Presenter's Affiliation: Graduate Research Assistant, Georgia State University Title: Frontal-to-parietal Theta Interactions Mediate Tactile Decision-making Location: In-Person Presentation, Kennesaw Show/Hide Abstract Decision-making relies on coordinated neural dynamics that integrate sensory evidence with top-down control. In this EEG study, we examined sensor (scalp)-level theta and alpha-band oscillations, as well as fronto-parietal network connectivity, during a tactile spatial discrimination task. Blindfolded participants judged the lateral offset of the central dot in a three-dot array delivered to the right index finger while an EEG was recorded. Time–frequency analyses revealed that both theta and alpha power were greater for correct than incorrect decision trials during pre-stimulus and post-stimulus intervals, suggesting enhanced preparatory and mnemonic engagement during accurate decisions. Directional connectivity assessed using block (multivariate) Granger causality demonstrated significantly stronger frontal-to-parietal influence in the theta band during both pre- and post-stimulus periods for correct decisions, supporting the role of long-range theta communication for top-down control in guiding tactile judgment. These findings highlight theta-band fronto-parietal communication as a key mechanism supporting successful tactile decision-making.
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Abstract Number: ANPA2026N00075 Presenting Author: Bipin Lamichhane Co-Authors: nan Presenter's Affiliation: Tuskegee University Title: Aqueous Phase Reforming of Methanol Supported on Pt Single Atom Catalysts Supported on Transition Metal Carbides Location: In-Person Presentation, Kennesaw Show/Hide Abstract Low-temperature aqueous phase reforming of methanol (APRM) offers an energy-efficient route for hydrogen production compared to conventional steam reforming of alcohols/hydrocarbons. This process provides a sustainable alternative to fossil fuel combustion by utilizing bio-renewable hydrocarbons and water. Precious metals are typically employed as a catalyst in reforming reactions. However, their high cost and limited reserve hinder their use in large-scale hydrogen production. To address this challenge, single-atom catalysts (SACs) enable more efficient use of noble metals. Here, we perform density functional theory (DFT) calculations to investigate the stability of reaction intermediates on Pt SACs supported on TMCs and corresponding bare TMC surfaces. Binding energies (BEs) of intermediates are used to construct a free energy diagram of APRM, and all possible channels are explored. Our analysis identifies Pt SAC supported on WC(001) as the most effective catalyst for APRM. The calculated energy profiles and activation barriers indicate that methanol decomposition into CO and H, followed by CO conversion to CO2 via water gas shift reaction (WGSR), represents the primary route of APRM. Furthermore, the results show that Pt SAC on WC exhibits moderate activation barriers across the full APRM pathway compared to bare WC. Therefore, Pt SAC not only facilitates C-H bond cleavage in methanol but also enhances CO reforming through the water gas shift reaction. Furthermore, our microkinetic modeling agrees with DFT prediction.
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Abstract Number: ANPA2026N00072 Presenting Author: Ganga P Sharma Co-Authors: nan Presenter's Affiliation: Fairmont State University Title: Large Language Models In Radiotherapy: From Contouring to Clinical Intelligence Location: Virtual Presentation Show/Hide Abstract Radiotherapy is a key treatment in cancer care that uses precise radiation to destroy tumor cells while protecting healthy tissue. Modern radiotherapy workflows are complex and require careful planning, contouring, evaluation, and documentation. Radiotherapy with LLMs From Contours to Clinical Intelligence explores how large language models can support these workflows by converting technical planning data into useful clinical information. LLMs can help interpret contours, dose–volume histograms, and planning goals to generate plan summaries, basic evaluations, and structured reports. This can improve efficiency, reduce manual workload, and support more consistent communication in clinical practice. Early results show that LLMs can organize complex radiotherapy data into clear and meaningful outputs. However, their reliability, clinical validation, and safe integration into practice remain important challenges. Overall, LLMs show strong potential as supportive tools that connect treatment planning with clinical understanding in radiotherapy.
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Abstract Number: ANPA2026N00073 Presenting Author: Binod Aryal Co-Authors: Nawal K. Khadka; Laxman Mainali Presenter's Affiliation: Boise State University Title: Aggregation Of ?b-crystallin in The Human Lens Cortical Membrane Mediated By The R120G Mutation Location: Virtual Presentation Show/Hide Abstract The R120G mutation in ?B-Crystallin (?Bc) is associated with cataract formation, where ?Bc interacts with the lens membrane that forms ?Bc-membrane aggregates. However, the role of the R120G mutation in ?Bc membrane binding and the molecular basis of ?Bc-membrane aggregates remain unclear. This study aims to investigate how the R120G mutation affects membrane interaction and aggregate formation. Total lipids (lipids and cholesterol) were extracted from a single human lens with transparent lens cortex from 61-year-old donors using a monophasic extraction protocol. Iodometric assay is used to measure the oxidation level of lipid plus cholesterol peroxidation. Using a rapid solvent exchange method and sonication, small unilamellar vesicles (SUVs) were prepared, followed by the fusion of SUVs on the mica surface to form a supported cortical membrane. Human wild-type (WT) and R120G mutated ?Bc were recombinantly expressed using the standard protocol. WT- and R120G-?Bc were incubated with the cortical membrane at physiological temperature, and the interaction with the cortical membrane was monitored using atomic force microscopy. WT- and R120G-?Bc strongly interact with the supported oxidized cortical membrane, forming ?Bc-membrane aggregates. With increased incubation time, followed by the addition of protein, the amount and size of protein membrane aggregates increase significantly. Both small and large aggregates were observed, with the large-sized aggregates exhibiting a distinct feature: a central corrugated region, in contrast to the smooth periphery. Interestingly, the level of aggregation was more extensive when R120G-?Bc interacts with the cortical membrane. Furthermore, the size of the R120G-?Bc membrane aggregates was found to be larger compared to WT-?Bc membrane aggregates. R120G mutation in ?Bc significantly increases mutated ?Bc aggregation to the oxidized cortical membrane compared to WT-?Bc. The larger size of R120G-?Bc membrane aggregates likely contributes to light scattering and cataract development than that of WT-?Bc.
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Abstract Number: ANPA2026N00074 Presenting Author: Nawal K. Khadka Co-Authors: Binod Aryal; Laxman Mainali Presenter's Affiliation: Boise State University Title: Aggregation of The ?a-crystallin With Cataractous Human Eye Lens Lipid Membrane From 64- And 74-year-old Donors Location: Virtual Presentation Show/Hide Abstract ?A-crystallin binding of human lens membrane increases with cataract. Similarly, lens lipid peroxidation is more abundant in cataract lenses than in clear lenses. However, the role of ?A-crystallin binding to cataractous human lens membrane and the role of lipid and cholesterol oxidation in such binding are unclear. Here, we aim to elucidate the role of cortical and nuclear cataract grade and lipid plus cholesterol peroxidation in ?A-crystallin membrane binding. Two lenses from 64 - and 74-year-old human donors (both OSLN) were obtained and graded for cortical (CC) and nuclear cataract (NC), which contained CC1; NC1, and CC2; NC1, respectively. Total lipids (lipids plus cholesterol) peroxidation level in the total lipid extracts of cortical and nuclear regions of lenses was measured using an iodometric assay. We found that the peroxidation level in the cortical lipids was significantly higher than in the nuclear lipids for both lenses. Small unilamellar vesicles prepared from total lipid extracts were dispensed onto freshly cleaved mica under an atomic force microscope (AFM) to form supported cortical and nuclear membranes at physiological temperature. Images were acquired before and after incubation of ?A-crystallin on the control membrane, and the binding of ?A-crystallin to the membrane was imaged using AFM. The area of ?A-crystallin aggregates on the membranes was estimated. For both lenses, the percent membrane area occupied (PMAO) and average area of the ?A-crystallin aggregates in the cortical membrane were significantly higher than in the nuclear membrane, indicating that lipid peroxidation leads to higher membrane-bound ?A-crystallin aggregates. Such ?A-crystallin aggregation on the CM and NM likely acts as a scattering site for light passing through, in unison with thousands of membrane layers in the lens, leading to cataract formation.
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Abstract Number: ANPA2026N00078 Presenting Author: Anup Shrestha Co-Authors: Amba Datt Pant; Surendra Bahadur Chand; Anjan Dahal; Hari Shankar Mallik; Akihiro Koda; Burkhard Geil; Katshuhiko Ishida; Koichiro Shimomura Presenter's Affiliation: Independent Researcher (Formerly at Tribhuvan University), Nayabazar, Gorkha-7, Nepal Title: Monte Carlo Simulations of The Depth of Maximum Muon Dose in Tumors Location: Virtual Presentation Show/Hide Abstract Moun spin rotation/relaxation/resonance (µSR) method provides information of local electronic and spin dynamic states of materials. The method has been applied to life science studies such as electron transfer in protein [1], DNA [2], spin dynamics of human-brain ferritin [3], blood magnetism [4], etc. Also, the µSR method is capable of detecting low oxygen (O2) concentrations in bio-samples and has been proposed as a noninvasive tool to detect low O2 (hypoxia) in tumors [5], since no such tool is available currently [6]. Muon is like a light proton with around three times greater magnetic moment that makes it sensitive to magnetic field. Based on the interaction of muonium (bound state of a µ+ and an e-) with O2, depth-wise imaging of O2 content in tumors can be detected [7]. Advantages of proposed muon method—applicable at any temperature without an external magnetic field—over existing detection methods make it suitable technique for low O2 detection [5,7]. In addition, theoretical studies such as density functional theory (DFT) calculations [8] and Monte Carlo simulations [9] support experimental results by identifying muon stopping sites and estimating depths of muon doses, respectively.
To know the depth of maximum muon doses in brain and soft-tissue tumors, we performed Monte Carlo simulations using PHITS code [10]. The estimated muon energy to deposit maximum dose at the far end of a brain tumor is 28.92 MeV for both µ+ and µ- muons. For soft-tissue tumor, the muon energies were estimated to be 26.58 MeV for µ+ and 26.55 MeV for µ- [9]. The estimated energies are slightly higher than the energies required to achieve same depth in absence of tumor. Although, µ+ and µ- follow different interaction mechanisms in matter, they deposited similar doses in tissues when the beams of identical energy were irradiated.
References
[1] K. Nagamine et al., Physica B 289-290, (2000) 631–635; [2] E. Torikai et al., Hyperfine Interactions 138, (2001) 509–513; [3] L. Bossoni et al., J. Phys.: Condensed Matter 29, (2017) 415801; [4] K. Nagamine et al., Physica B 374-375, (2006) 444–447; [5] A. D. Pant et al., Nuclear Instruments and Methods in Physics Research A, 1011 (2021) 165561; [6] J. P. B. O’Connor et al., Cancer Research 76, (2016) 787–795; [7] A. D. Pant et al., JPS Conference Proceedings (accepted); [8] R. Pudasaini et al., Interactions 245, (2024) 34; [9] A. Shrestha et al., Interactions 247, (2026) 48; [10] T. Sato et al., J. Nucl. Science and Technology 61, (2024) 127–135.
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Abstract Number: ANPA2026N00079 Presenting Author: Jevaan Govender Co-Authors: Conner Campbell; Ihssane Damoh; Luke Babak; Joshua Gomez Mery; Gabriel Nicolas Maurer; Wissal Essafyani; Dimitri Sourov; Indra D. Sahu Presenter's Affiliation: Campbellsville University Title: Utilization of Styrene–maleic Acid Lipid Particles (smalps) for Studying Structural Dynamic Properties Oof KcNe3 Via EPR Spectroscopy Location: Virtual Presentation Show/Hide Abstract Electron Paramagnetic Resonance (EPR) Spectroscopy serves as a valuable technique for probing the conformational dynamics of membrane proteins. Despite its usefulness, conducting EPR experiments on these proteins remains difficult largely because it is challenging to maintain them in evenly distributed stable state within membrane environments. Several membrane mimetic systems are routinely used including detergent micelles, bicelles, lipid bilayers, and nanodiscs, but each system presents specific strengths and drawbacks, and none is universally suitable for all membrane protein syatems. More recently, styrene–maleic acid lipid particles (SMALPs) have emerged as a promising alternative, offering a more uniform lipid bilayer formation. However, the motional behaviour of spin-labelled membrane proteins within SMALPs has not yet been thoroughly explored. In this work, site-directed mutagenesis was used to replace amino acid residues of the voltage-gated potassium channel accessory protein KCNE3 with cysteine residues, enabling the covalent attachment of the nitroxide spin label MTSL required for EPR spectroscopic measurements. To probe structural dynamics, the spin-labelled protein was reconstituted into SMALPs using a mixture of POPC and POPG lipids (3:1), allowing for a direct comparison between liposomes and SMALPs environments. Continuous-wave EPR spectral lineshape analysis performed on several spin-labeled KCNE3 mutants along transmembrane domain and N- and C-termini demonstrated that samples containing the SMA polymer exhibited noticeably broader spectral line shapes compared to those prepared in liposomes. This observation indicates reduced mobility of the spin label and thus increased restriction of protein motion within the SMALP environment. Collectively, these results establish a comparative framework that advances the understanding of membrane protein dynamics across different membrane mimetic systems and supports future biophysical studies.
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Abstract Number: ANPA2026N00080 Presenting Author: Amba Datt Pant Co-Authors: nan Presenter's Affiliation: KEK/J-PARC center, Japan Title: Fundamentals of Muon Biology for Hypoxia Imaging Location: Virtual Presentation Show/Hide Abstract Hypoxia, or low oxygenation, plays a vital role in the diagnosis and treatment of tumors and cancer [1]. While there are several methods with limitations to detect hypoxia, we propose a noninvasive muon method to measure the presence, extent, and spatial distribution of hypoxia within tumors via the direct interaction of muon species with O2 [2]. The proposed method has been tested by detecting low O2 concentrations in dilute protein solutions [3].
For further formulation of muon interactions with biomolecules and development of the method, we initiated muon spin rotation and relaxation studies on constituents of biosamples (water [4,5], O2 dissolved in water [6], buffer [7], and hemoglobin derivatives [8]). We found the formation of the MuOH molecule and the origin of the relaxation of muon spectra which is due to quantum coherence of muon in water below the freezing point [4]. In separate aqueous solutions of buffer and hemoglobin, similar to water, we found a similar pattern and muon species (diamagnetic muon and isotropic muonium in the liquid phase, and diamagnetic MuOH, anisotropic muonium, and another diamagnetic muon in frozen water) albeit with different interaction behaviors. In this presentation, recent achievements to establish the fundamentals of muon biology for imaging of hypoxia will be discussed.
References
[1] A. Harris, Nat. Rev. Cancer 2, 38–47 (2002)
[2] J. L. Tatum, et al., Int. J. Radiat. Biol., 82 (2006), pp. 699-757
[3] A. D. Pant et al., Nucl. Instrum. Methods Phys. Res. A, 1011 (2021) 165561; J. Phys.: Conf. Ser., 551 (2014), 012043
[4] A.D. Pant, et al., Phys. Rev. B 110 (10), 104104
[5] A.D. Pant, et al., J. Phys. Soc. Jpn. 95 (1), 014603
[6] A. D. Pant et al., JPS Conf. Proc. 45 (2026) (in press)
[7] A. Dahal, M. Sc. Thesis, (2025) Central Dept. Physics, T.U., Nepal
[8] A. Shrestha, M. Sc. Thesis, (2025) Central Dept. Physics, T.U., Nepal
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Abstract Number: ANPA2026N00081 Presenting Author: Anjan Dahal Co-Authors: Amba Datt Pant; Hari Shankar Mallik; Anup Shrestha; Akihiro Koda; Katsuhiko Ishida; Burkhard Geil;Hiromi Sakai; Jumpei G. Nakamura; Koichiro Shimomura; Presenter's Affiliation: Manthali Secondary School Title: Quantum Coherence of Muon in Buffer Location: Virtual Presentation Show/Hide Abstract To build a fundamental understanding of muons behavior in biological systems and its possible applications in cancer research-we perform muon spin rotation and relaxation (?SR) study starting from constituents of biological samples – water [1], O2 dissolved in water [2], buffer [3], hemoglobin [4,5], etc. to know the interactions of muon and its species. In liquid water, muonium (a bound state of a positive muon and an electron, Mu which is like a light isotope of H), shows spin-dipole interactions with O2 and provides the relaxation in time spectra which helps to estimate the existence of O2 in the solution [6]. However, in frozen water, injected muon replaces one of the protons of the water and forms MuOH which shows the quantum coherence with spin-environment [7,8]. These studies provide the background information when ?SR study apply to real/intact biomolecules/tissue.
In the ?SR technique, spin-polarized positive muons are implanted into a sample, provides the local magnetic and spin dynamics states of the material. In biological case, the ?SR provides information about O2 concentration, oxidative reactions, electron transport and local structure changes. As Mu was found to have oxygen concentration dependent behavior [6] and cancer cells tend to have low O2, the ?SR technique has been proposed as a non-invasive tool for hypoxia detection.
We performed field and temperature-dependent ?SR study on phosphate saline buffer (PBS) using positive muon at S1, MLF, J-PARC, Japan. An isotropic Mu has been observed in liquid PBS and anisotropic muonium has been observed in frozen PBS indicating the interaction between muon and its nearby spin system. In this talk, muon quantum interaction with nearby spin-system in PBS like that observed in water [8] will be discussed.
References
[1] A. D. Pant et al, Physical Review B 110, 104104 (2024); [2] A.D. Pant et al, JPS Conf Proceedings (accepted) [3] A. Dahal, Anisotropic Muonium Observed in PBS, M.Sc. Thesis, Central Department of Physics, T.U., Kritipur, Nepal (2025), [4] A. Shrestha, Behavior of Muon and Muonium in Oxyhemoglobin Solutions, M.Sc. Thesis, Central Department of Physics, T.U., Kritipur, Nepal (2025); [5] R. Pudasaini et al. Hyperfine Interact 245, 34 (2024); [6] A. D. Pant et.al, Nuclear Instruments and Methods in Physics Research Section 1011, 165561(2021); [7] A. D. Pant et.al, J. Phys. Soc. Jpn 95, 014603 (2026); [8] A. D. Pant et al, APS (submitted).
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Abstract Number: ANPA2026N00082 Presenting Author: Deependra Awasthi Co-Authors: Narayan Gautam; Shyam P. Khanal; Rajendra Prasad Koirala; Narayan P. Adhikari Presenter's Affiliation: Hokkaido University, Japan Title: Thermodynamic Aand Transport Properties of Alkanes (CnH2n+2; N = 5–8) Location: Virtual Presentation Show/Hide Abstract In the present work, we have utilized “alchemical” approaches to study the thermodynamic properties of four alkane molecules:
pentane, hexane, heptane, and octane in water. We have used thermodynamic integration (TI) and free energy perturbation (FEP)
based methods: TI, TI-cubic, Bennett acceptance ration (BAR), and Multistate Bennett acceptance ratio (MBAR)to estimate the
solvation free energy of alkane molecules in water at 300 K for 21 distinct coupling parameter values (?). For each alkane
molecule, the estimated values of solvation free energy using the different methods are in close agreement, which ensures
the reliability of our study. Convergence of the calculation has also been examined through time series plots in both forward
and reverse directions. Our study shows that the solvation free energy increases with increasing size of the alkane molecules,
which is also supported by estimation of solvent accessible surface area (SASA). The self diffusion coefficients of both solutes and
solvent molecules; and shear viscosity of the systems have been estimated at 293 and 300 K temperatures. The self diffusion
coefficient of the alkane molecules decreases with increase in size and shear viscosity increases with chain length as expected.
The estimated values of diffusion and shear viscosity are in close agreement with the previously reported values.
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Abstract Number: ANPA2026N00084 Presenting Author: Santosh Sodari Co-Authors: Amba Datt Pant Presenter's Affiliation: Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal Title: Estimation of Muon Stopping Sites in Fecl? and Zncl? Using DFT+U Method Location: Virtual Presentation Show/Hide Abstract Estimation of Muon Stopping Sites in FeCl? and ZnCl? using DFT+? Method
Santosh Sodari¹ and A. D. Pant²
¹Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal
²High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
Corresponding Author: santoshsodari@gmail.com
Hemoglobin plays a crucial role in the transportation of molecular oxygen (O?) in tissues. In tumor, the O? concentration is significantly lower than that in normal tissues [1], a condition known as hypoxia. Detection of hypoxia is important for the diagnosis and treatment management of tumors [2]. Using positive muons available at accelerator facilities, a non-invasive muon-based method for detecting hypoxia has been proposed and tested its sensitivity in dilute protein solutions [3]. To interpret muon spectra obtained from hemoglobin, it is necessary to understand how muons and their charge species interact with the iron (Fe) center in the heme group and with other molecules such as unsaturated organic compounds. Identifying muon stopping sites and charge states in hemoglobin is experimentally challenging [4]; therefore, theoretical study through first-principles calculations is necessary. As a step toward understanding muon–Fe interactions in hemoglobin, we perform density functional theory (DFT+? ) calculations muon in Fe- and Zn-containing halides, namely FeCl? and ZnCl?.
The DFT+? calculations were performed using the Quantum ESPRESSO suite, employing a supercell approach to simulate the dilute muon limit. Structural relaxations of FeCl? and ZnCl? are carried out using the BFGS algorithm with spin-polarized treatment, D3-Grimme van der Waals corrections, and Zero-Point Energy (ZPE) corrections to properly account for the light mass of the muon. Stopping sites of muon and muonium have been estimated through electrostatic potential energy mapping, followed by full structural relaxation of muon-embedded supercells and comparing with bare-muon case. In the program, estimation of stopping sites of muon and muonium in both samples will be discussed.
References
[1] I. Godet, et al., Cells, 11 (4) (2022) 686.
[2] J. L. Tatum, et al., Int. J. Radiat. Biol., 82 (10) (2006) 699–757.
[3] A. D. Pant, et al., Nucl. Instrum. Methods Phys. Res. A, 1011 (2021) 165561.
[4] A. D. Pant, et al., Phys. Rev. B 110 (2024) 104104.
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Abstract Number: ANPA2026N00085 Presenting Author: Tej Andhari Co-Authors: Adam Le, Krishna P. Sigdel Presenter's Affiliation: California State Polytechnic University, Pomona Title: Direct Visualization of Melittin-induced Defects on The POPC-supported Lipid Bilayer Location: Virtual Presentation Show/Hide Abstract Antimicrobial peptides (AMPs) cause a wide range of effects when interacting with cell membranes, depending on the AMP’s properties. Melittin, a linear antimicrobial peptide consisting of 26 amino acid residues, is a major toxic component in the venom of the European bee Apis mellifera. The interactions between melittin and cell membranes have been studied extensively through various biochemical assays. However, the mechanistic details behind the effect of melittin on membrane destabilization are still elusive. In this study, we used atomic force microscopy (AFM) to explore the effects of melittin on a supported lipid bilayer formed by phosphatidylcholine (POPC) lipids (a model Eukaryotic cell membrane). We tested various concentrations to gain insight into the resulting patterns of pore formation or membrane lysis. Our study sheds light on how melittin interacts with a supported lipid bilayer that mimics a eukaryotic cell membrane.
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