Temperature Ramp Research Articles

Rapid Determination of Five Residual Solvents in Ursodeoxycholic Acid Raw Materials

The chromatographic conditions were optimized using headspace gas chromatography, and a simple and rapid method was established for the simultaneous determination of five residual solvents in ursodeoxycholic acid raw materials. The corresponding quality standards were revised. The research results demonstrate that by utilizing a capillary column with a stationary phase consisting of 5% phenyl-95% dimethylpolysiloxane (HP-5, 30 m × 0.32 mm, film thickness 1.0 µm) and a flame ionization detector in conjunction with a headspace injection system and a programmed temperature ramping method, satisfactory analytical results can be achieved. The specific operating conditions are as follows: an initial column temperature of 45 °C, followed by a column temperature increase at a rate of 5 °C per minute up to 60 °C, then a further increase at a rate of 10 °C per minute up to 100 °C, and finally a rapid increase at a rate of 40 °C per minute up to 200 °C, where it is held for 10 min. Nitrogen is employed as the carrier gas at a flow rate of 1 mL/min with a split ratio of 14:1. The headspace vial temperature is maintained at 100 °C, with a sample equilibration time of 45 min. The concentration of methanol ranged from 0.06 mg/mL to 0.3 mg/mL, and the concentrations of acetone, tert-butanol, ethyl acetate, and triethylamine showed a good linear relationship with the peak area within the range of 0.1 mg/mL to 0.5 mg/mL (r = 0.999); The quantitation limits for methanol, acetone, tert-butanol, ethyl acetate, and triethylamine were 4.2, 0.9, 1.5, 1, and 0.1 μg/mL, respectively, with detection limits of 1.2, 0.25, 0.025, 0.3, and 0.025 μg/mL, respectively. The recovery rates of each solvent ranged from 92.9% to 106.0%, with RSD% (n = 9) less than 3.8%; the method exhibited good repeatability, with RSD% (n = 6) less than 2.5%. Furthermore, the robustness is good. The established method is simple, accurate, specific, and highly sensitive, and can be used for the simultaneous and rapid determination of five residual solvents in ursodeoxycholic acid raw materials.

Impact of Incorporating Free Calcium and Magnesium on the Heat Stability of a Dairy- and Soy-Protein-Containing Model Emulsion.

This study investigated the impact of calcium chloride (CaCl2) and magnesium chloride (MgCl2) at varying concentrations on a model milk formulation's physical and chemical properties after thermal treatment. The model milk was subjected to two-stage homogenization and pasteurization before being supplemented with different concentrations of CaCl2 or MgCl2. The findings revealed that elevating the concentration of either calcium or magnesium resulted in the milk emulsion having a higher viscosity and median particle size following heating. CaCl2 had a slightly stronger impact than MgCl2, particularly at higher concentrations. The milk samples also exhibited a reduction in the zeta potential as the ionic strength of the salt solution increased, with the CaCl2-fortified milk displaying a slightly lower negative surface charge than the MgCl2-fortified milk at the same dose. The model milk's viscosity was evaluated after adding various salt concentrations and a temperature ramp from 20 to 80 °C. Notably, the viscosity and particle size changes demonstrated a non-linear relationship with increasing mineral levels, where a significant increase was observed at or above 5.0 mM. An emulsion stability analysis also revealed that the de-stabilization pattern of the high salt concentration sample differed significantly from its low salt concentration counterparts. These findings could serve as a basis for the future development of fortified UHT milk with nutritionally beneficial calcium and magnesium in industrial applications.

EXTH-30. GOLD NANOSTARS OBVIATE LIMITATIONS TO LASER INTERSTITIAL THERMAL THERAPY (LITT) AND ENHANCE THE POST-LITT IMMUNE RESPONSE

Abstract Laser interstitial thermal therapy (LITT) is a minimally-invasive technique for the treatment of intracranial tumors that uses a stereotactically-guided laser and real-time magnetic resonance imaging (MRI) to monitor ablation progress. Previous applications of gold nanostars (GNS) in laser ablation of tumors have studied extracranial tumors only and utilized externally administered near infrared radiation that cannot penetrate the cranial compartment. Herein, we present a novel platform for employing GNS in intracranial tumors. We developed non-toxic GNS that exhibit maximum photothermal effects at the 1064 nm laser wavelength used in the FDA-approved clinical Neuroblate® LITT system. Monte Carlo simulations demonstrate that our GNS can accelerate and focus thermal energy distributions. Using ex vivo tumor phantom models, we found that GNS-infused phantoms demonstrate more rapid heating and improved spatial conformation of thermal energy, with neighboring material exposed to lower temperatures than controls. In our intracranial CT-2A glioma model, we quantified accumulation of radiolabeled GNS in tumor tissue via PET/CT. As further validation of tumor-selective GNS accumulation, we used two-photon luminescence to show that GNS selectively accumulate and are retained in intracranial tumors at 24 and 72 hours post-injection. We then utilized our in vivo heterotopic CT-2A model to assess the capacity of systemically-delivered GNS to augment laser ablation; we were able to achieve higher ablation temperatures and more efficient temperature ramping with LITT+GNS. Finally, we explored the potential of LITT+GNS to synergize with immunotherapy to further enhance the post-ablation immune response and found that combination therapy resulted in improved tumor control and immunologic memory that was protective against tumor rechallenge. These results support the ability of GNS to optimize LITT for the treatment of intracranial tumors by improving efficiency and safety, and illustrate the potential of this platform to synergize with immunotherapy.

Stage changes in the oxidizing properties of long-term water-soaked coal and analysis of key reactive groups

To elucidate the impact of prolonged water immersion on the evolution of key active functional groups during the low-temperature oxidation of coal, the programmed temperature ramping method, in-situ Fourier transform infrared spectroscopy (in-situ FTIR), microcalorimetry (C80) experiments, thermodynamic analysis, and gray and Pearson correlation analysis were performed. The analysis involved coal samples exposed to different immersion durations (3, 6, 9, and 12 months). The results reveal that long-term water immersion exerts a stage-wise influence on the oxidation characteristics of coal, with the critical time point being 6 months. Before this period, the gradual accumulation of active sites progressively enhances the oxidation characteristics. However, after 6 months, the generation of active sites is suppressed, resulting in a gradual weakening of the coal's oxidation behavior. Correlation analysis revealed that the correlation between free hydroxyl groups and gaseous products is strongest in coal immersed for 6 months (A6), with a correlation coefficient of 0.91. During the accelerated oxidation stage, the heat released from the soaked coal is significantly greater than that in other stages, which promotes the formation of C=O and –COOH functional groups and further reduces the apparent activation energy. According to the Coats–Redfern method, A6 exhibits the smallest apparent activation energy—only 30 % of the original value of coal. The correlation between free hydroxyl groups and apparent activation energy is strongest at this stage, with a correlation coefficient of 0.92. This indicates that free hydroxyl groups and the accelerated oxidation stage are, respectively, the key active functional groups and critical phases in the coal oxidation process.

The Potential of Mangifera indica L. Peel Extract to Be Revalued in Cosmetic Applications.

The constant growth of the cosmetic industry, together with the scientific evidence of the beneficial properties of phytochemicals, has generated great interest in the incorporation of bioactive extracts in cosmetic formulations. This study aims to evaluate the bioactive potential of a mango peel extract for its incorporation into cosmetic formulations. For this purpose, several assays were conducted: phytochemical characterization; total phenolic content (TPC) and antioxidant potential; free-radical scavenging capacity; and skin aging-related enzyme inhibition. In addition, the extract was incorporated into a gel formulation, and a preliminary stability study was conducted where the accelerated (temperature ramp, centrifugation, and heating/cooling cycles) and long-term (storage in light and dark for three months) stability of the mango peel formulations were evaluated. The characterization results showed the annotation of 71 compounds, gallotannins being the most representative group. In addition, the mango peel extract was shown to be effective against the •NO radical with an IC50 of 7.5 mg/L and against the hyaluronidase and xanthine oxidase enzymes with IC50 of 27 mg/L and 2 mg/L, respectively. The formulations incorporating the extract were stable during the stability study. The results demonstrate that mango peel extract can be a by-product to be revalorized as a promising cosmetic ingredient.

Numerical Computation of Williamson Hybrid Nanofluid Flow Over the Curved Surfaces With Effects of Thermal Radiation

Abstract The current investigation is based on Williamson's features of a hybrid nanofluid flow over a curved surface made mixture of silver (Ag) and titanium dioxide (TiO2) with engine oil. Under the presumption of a low magnetic Reynolds number, a constant homogenous magnetic field is applied. Consideration is given to the ramping temperature and the time-varying surface concentration. Thermal absorption and first-order consistent chemical reaction are also taken into account. To create a hybrid nanofluid, silver (Ag), and titanium nanoparticles are dispersed in a base fluid made of water and engine oil. Quasi-linearization technique and Finite difference scheme are employed on the nondimensional partial differential equations. All physical parameters of practical importance, such as velocity, temperature, and concentration profile are analyzed and provided in tables and graphs along with the impact of physical parameters. As the Williamson parameter (W) increases, the surface velocity of the steep plate decreases. Also, as the parameter temperature ratio of Nt and Rd increases, the forces opposing the flow field reduce the friction force, and the thermal field increases with temperature effects.

Pyrolysis and Combustion Characteristics of Two Russian Facemasks: Kinetic Analysis, Gaseous Emissions, and Pyrolysis By-Products

Pyrolysis and combustion experiments were performed on two facemasks (hereafter named Tissue and Surgical) commonly used in the Russian Federation, first in a thermobalance and under four low-temperature ramps (5, 10, 15, and 20 °C/min). The pyrolysis mass rate curves present a unique devolatilization peak. The combustion mass rate curves present a unique devolatilization peak followed by a shoulder or a small further peak on its right-hand side. Both processes mainly occur between 200 and 500 °C. Simulations of these pyrolysis and combustion processes are performed with good agreement using the extended independent parallel reaction (EIPR) model. The gas chromatography technique was used to analyze the by-products of pyrolysis experiments performed under isothermal temperatures of 300, 400, and 500 °C. Combustion experiments were finally performed in a horizontal oven under a temperature ramp approximately equal to 5 °C/min to measure the main gaseous emissions: CO2 emissions are the main emissions of the Tissue mask, while total hydrocarbons are the main emissions of the Surgical mask. Significant differences are observed between the results obtained for the two masks because of the fibers they are built with (natural or synthetic).

Formation of Colloidal In(As,P) Quantum Dots Active in the Short-Wave Infrared, Promoting Growth through Temperature Ramps.

Colloidal InAs quantum dots (QDs) are widely studied as a printable optoelectronic material for short-wave infrared (SWIR) that is not restricted by regulations on hazardous substances. Such applications, however, require synthetic procedures that yield QDs with adjustable sizes at the end of the reaction. Here, we show that such one-size-one-batch protocols can be realized through temperature profiles that involve a rapid transition from a lower injection temperature to a higher reaction temperature. By expediting the transition to the reaction temperature and reducing the overall synthesis concentration, we can tune QD sizes from 4.5 to 10 nm, the latter corresponding to a band gap transition at 1600 nm. We argue that the temperature ramps provide a more distinct separation between nucleation at low temperature and growth at high temperature such that larger QDs are obtained by minimizing the nucleation time. The synthetic procedures introduced here will strongly promote the development of a SWIR optoelectronic technology based on InAs QDs, while the use of temperature profiles to steer a colloidal synthesis can find applications well beyond the specific case of InAs QDs.

Physical properties with high specific loss power of magnetite (Fe3O4) synthesized via thermal decomposition technique

Magnetic iron oxide nanoparticles have versatile applications in biomedical science that require control over shape and size distribution. Thermal decomposition is one of the best methods for controlling the size and shape of produced nanoparticles (NPs). The size distribution can be tuned (5–30 nm) by varying the reaction environment such as precursor concentration, amount of solvent used, temperature ramp, and reflux time. Iron oleate was used as a precursor solution and heated up to reflux temperature (310 °C) for 10 min within the oxygen-free environment by applying N2 gas flow. The XRD pattern confirmed the formation of NPs with a crystallite size of 17 ± 2.45 nm. Transmission electron microscope images showed moderately cubic shapes with a mean particle size of 28.67 ± 7.12 nm. Magnetic properties such as saturation magnetization, coercivity, and remanence were calculated at 23.48 emu/gm, 33 Oe, and 0.6 emu/gm, respectively, which indicated the ferromagnetic nature of the NPs. The Verwey transition was identified from the magnetization vs temperature (FC-ZFC) plot. The bondings of the oleic acid surfactant with the produced NPs were confirmed from Fourier transformation infrared spectroscopy (FTIR) data analysis. For the application of hyperthermia, the hydrophobic phase was transferred to the hydrophilic phase using cetyltrimethylammonium bromide, which was assured by the FTIR data analysis. The hyperthermia heating of NPs was measured for different concentrations of NPs (0.25, 0.5, 1, 2, and 4 mg/ml), from which specific loss power (SLP) was calculated. Among them, 0.25 mg/ml produced the most prominent SLP (2149 ± 309 w/g) that can be applied for targeted cancer treatment.

Halogenated polymers as a problematic component in the pyrolysis of waste plastics

The study deals with the complications associated with the pyrolysis of a polymer releasing highly corrosive compounds and other products that are difficult to be utilized in practice. Poly(vinyl chloride-vinyl acetate) was chosen as a sample material. This copolymer was subjected to slow pyrolysis up to a temperature of 650 °C, which was achieved with a temperature ramp of 10 °C min‒1. Thermal decomposition took place in a batch apparatus in nitrogen atmosphere. The evaluation of the experiments included a mass balance using an online recording of gas and condensate formation, which was followed by an analysis of the obtained products. The tests showed very small yields of condensates (pyrolysis tar) in the range of 3.0 – 5.5% compared to gas production reaching 71.1 – 72.1% of the raw material weight. Within the discussion, the problem with the production of non-flammable gas consisting mainly of HCl in the initial stages of pyrolysis was highlighted. Under the given conditions, the release of acid gases, in which HCl was gradually replaced by also non-flammable CO2, continued up to about 400 °C. Only gases collected from this temperature above and having a calorific value of 33.5 MJ m‒3 (20 °C / 101.32 kPa) can be considered energetically usable. Condensates mainly represented by a mixture of aromatic hydrocarbons, acetic acid and chlorobenzene were also evaluated as problematic for possible use. The possibilities of physical activation of solid pyrolysis residues by steam at temperatures of 850 and 900 °C were also tested. All experiments led to obtaining products with very small specific surface areas in the range of 1 – 6 m2 g–1. The process loss during activation reached 25 – 33% of the pyrolysis residue weight, depending on the applied temperature and contact time with steam. These values show that the reaction of the activation medium with the sample took place more or less only on the outer surface of the particles and did not lead to the development of an internal porous structure. The achieved results were compared with the identically processed samples of waste tires, which were evaluated as promising in tests carried out in the past. The contrast be-tween the two materials clearly spoke against the discussed copolymer. The results of the experiments can be interpreted, among other things, as a certain warning against attempts at industrial pyrolysis processing of this type of plastic.

Transient testing of oxide fuels by spark plasma sintering and finite element analysis

In this paper, we report an innovative approach of using spark plasma sintering (SPS) combining with finite element modeling (FEM) to investigate the transient behavior of nuclear fuels. The temperature ramping rates of the SPS with special tooling can be controlled from 5 to 10 °C/s up to 500 °C/s, mimicking prototypical thermal profiles of the loss-of-coolant-accident (LOCA) and reactivity-induced-accident (RIA) events, respectively. The fresh UO2 pellets with micron grain size are synthesized by SPS. Their fracture and fragmentation behaviors are investigated under transient thermal testing, and temperature-gradient and thermal-stress are calculated by FEM. The micron-sized fresh UO2 displays good thermal shock stability and anti-cracking performance under the LOCA thermal test. Under simulated RIA conditions, the UO2 fuels crack due to the stress induced by the large thermal gradient. The unique capability of SPS with controlled temperature ramping enables a cost-effective approach for rapid screening and high throughput evaluation of nuclear fuels under power transients.

Semiautomated Electrochemical Melting Curve Analysis Device for the Detection of an Osteoporosis Associated Single Nucleotide Polymorphism in Blood.

The detection of single nucleotide polymorphisms (SNPs) is of increasing importance in many areas including clinical diagnostics, patient stratification for pharmacogenomics, and advanced forensic analysis. In the work reported, we apply a semiautomated system for solid-phase electrochemical melting curve analysis (éMCA) for the identification of the allele present at a specific SNP site associated with an increased risk of bone fracture and predisposition to osteoporosis. Asymmetric isothermal recombinase polymerase amplification using ferrocene labeled forward primers was employed to generate single stranded redox labeled amplicons. In a first approach to demonstrate the proof of concept of combining asymmetric RPA with solid-phase éMCA, a simplified system housing a multielectrode array within a polymeric microsystem, sandwiched between two aluminum plates of a heater device, was used. Sample manipulation through the microfluidic channel was controlled by a syringe pump, and an external Ag/AgCl reference electrode was employed. Individual electrodes of the array were functionalized with four different oligonucleotide probes, each probe equivalent in design with the exception of the middle nucleotide. The isothermally generated amplicons were allowed to hybridize to the surface-tethered probes and subsequently subjected to a controlled temperature ramp, and the melting of the duplex was monitored electrochemically. A clear difference between the fully complementary and a single mismatch was observed. Having demonstrated the proof-of-concept, a device for automated éMCA with increased flexibility to house diverse electrode arrays with internal quasi-gold reference electrodes, higher resolution, and broader melting temperature range was developed and exploited for the detection of SNP hetero/homozygosity. Using the optimized conditions, the system was applied to the identification of the allele present at an osteoporosis associated SNP site, rs2741856, in 10 real fingerprick/venous blood samples, with results validated using Sanger sequencing.

Stresses in pipes subject to thermal fluctuations and linear temperature ramps

Closed-form exact expressions for local and linearized elastic thermal stresses in thick- and thin-walled circular pipes subject to steady-periodic sinusoidal temperature variations are presented. Fourier series are applied to obtain the corresponding response in the pipe wall to rectangular temperature fluctuations and linear temperature ramps. Universal diagrams of resulting temperatures and stress ranges in terms of dimensionless parameters are shown for various pipe cross sections, load frequencies and heat transfer coefficients for the three types of loads.

Influence of plasma inhomogeneity and ohmic heating on the nonlinear absorption of intense laser pulse in collisional magnetized plasma

AbstractThe nonlinear absorption in the interaction of an intense laser pulse with a collisional magnetized plasma is studied by considering the effects of plasma inhomogeneity, ohmic heating, and ponderomotive force. For this purpose, we obtain the plasma electron density, the effective dielectric permittivity, and the wave equation using the Maxwell and hydrodynamic equations and solve this equation by the Runge–Kutta numerical method. The results are shown that by increasing the plasma inhomogeneity, the inverse bremsstrahlung absorption coefficient is increased, and also the density ramp parameter and its sign can affect more the absorption coefficient than the temperature ramp parameter . However, when the initial electron density and temperature increase, the laser field amplitude and the absorption coefficient are increased and the spatial damping rate of the laser pulse becomes highly peaked inside the plasma. It is shown by increasing laser pulse energy, the nonlinear bremsstrahlung absorption coefficient is decreased significantly. The results also indicate that by increasing the external magnetic field, the dielectric permittivity is decreased while the laser energy spatial damping, and the absorption coefficient are increased. Moreover, it is found that by considering the ohmic heating effect, the electrons absorb further energy from the fields and consequently the nonlinear absorption is increased.

A molecular-kinetic theory based model for alkali liquid metal boiling incipience analysis

Boiling can lead to unexpected heat transfer performance of the components using alkali liquid metal (ALM) as working fluid for high thermal conductivity. Thus study on incipient boiling superheat of ALM is important to the design and safety operation of related components. However, existing data are in large scatter and some important parameter trends are inconsistent, indicating that more research should be done to understand the basic mechanism of ALM boiling incipience. In this paper, the local heat transfer of a wall cavity was investigated and the molecule performance at the three-phase contact line (TPL) was analyzed with molecular-kinetic theory. It was found that during transient process, the liquid temperature distribution near the interface in the cavity may result in considerable unbalanced molecule displacement at TPL and change the contact angle significantly. By estimating the evaporation rate at TPL with interface deformation rate and local temperature gradient, a model which could correlate nucleation contact angle as well as nucleation superheat with heat flux, velocity and interface deformation rate was established. The model was then used to predict the nucleation superheat data involving effects of temperature ramp, heat flux and velocity, and good agreement was gained. Besides, the characteristics of nucleation superheat of different heating methods were also analyzed and the trend of velocity effect was discussed, and some phenomena observed in different experiments were explained.

Sustainable production of hydrogen and carbon nanotubes/nanofibers from plastic waste through microwave degradation

Plastic waste pyrolysis to clean energy (H2) and valuable carbon nanotubes or nanofibers (CNTs/CNFs) is the most promising waste management and energy regeneration process. In this study, microwave-mediated single-step pyrolysis is used to produce COx-free hydrogen and CNTs/CNFs from real-world plastic films. Nickel, iron, and cobalt-based catalysts were prepared by the incipient wet-impregnation method and tested for real-world polyethylene plastic film degradation. In addition, the quality of CNTs produced and hydrogen yield were also compared for these catalysts. Various characterization tools were used to characterize the calcined catalysts, spent catalysts, and CNTs. Further, the effect of temperature ramp rate on hydrogen yield and CNTs properties was also analyzed. The results show that the iron-based catalyst produces a high yield of hydrogen and low-diameter and uniform-quality CNTs compared to other catalysts.

Dynamic Change of Rh Oxidation State During Lean‐Rich Perturbation and Light‐Off of Three‐Way Catalysis Analysed using In Situ Diffuse Reflectance UV‐vis Spectroscopy

AbstractThis study investigated the redox behaviour of Rh in three‐way catalysts (TWC) using time‐resolved in situ diffuse reflectance UV‐vis spectroscopy in different modes with air‐to‐fuel ratio (A/F) step, A/F perturbation, and temperature ramping. When Rh/ZrO2−CeO2 (Rh/ZC) and Rh/ZrO2 (Rh/Z) containing fully oxidised Rh were treated at 400 °C under simulated TWC conditions with A/F stepping from 15.0 (fuel‐lean) to 14.1 (fuel‐rich), a steep increase in the metallic fraction (Rh0/Rh) and a simultaneous increase in Kubelka–Munk function (ΔKM) at λ=450 nm occurred near the stoichiometric point (A/F=14.6). Metallic Rh became abundant until A/F=14.1, where the largest ΔKM was attained. In the A/F perturbation mode, the Rh oxidation state fluctuated with repetitious switching of rich and lean gas feeds, but the ΔKM oscillation amplitude was lessened for Rh/ZC compared to Rh/Z because of the oxygen‐scavenging function of ZC. Furthermore, the changes in Rh oxidation state during TWC light‐off were analysed in the temperature‐ramping mode. Under rich conditions, Rh0/Rh and ΔKM increased after 200 °C, where the formation of Rh metal led to efficient conversions of CO and NO. However, metallic Rh did not appear during light‐off under the lean condition, where NO conversion was negligible.

Thermoregulatory responses of young and elderly adults under temperature ramps

As the world population ages, there is a growing focus on the health and well-being of elderly individuals. In line with this, research findings are now highlighting the potential threats that extreme climates pose to the health of the elderly. Therefore, this study aims to investigate age differences in thermoregulatory abilities under various temperature ramps. This study collected physiological and psychological responses from 20 elderly and 20 younger subjects in experiments involving four different temperature ramp types. The statistical approach was used to analyze the differences between ages and types of temperature ramps, and the results were analyzed in the view of thermoregulatory mechanisms. The results showed significant differences in thermoregulatory abilities between young and elderly subjects. By analyzing the overshooting and stabilization time, elderly individuals were found to have insensitive thermoreceptors and were more likely to have risks in maintaining homeostasis. Additionally, the study found that different types of temperature ramp affected thermoregulatory abilities differently for both age groups. This study can contribute by suggesting guidelines for elderly individuals regarding temperature ramps that can be formed outdoors and indoors.

Oscillatory and rotational rheological characterization of jackfruit peel cellulose suspension: Effect of concentration, pH and ionic strength

Jackfruit peel (JP) is considered as an agro-industrial lignocellulosic waste which can be utilized for cellulose isolation. In this work, a yield of 25.6% cellulose was obtained from JP powder through alkali (NaOH) and bleaching (NaClO2) treatment along with the elimination of lignin, hemicellulose and other non-cellulosic constituents. The IR spectroscopy confirmed the existence of cellulose content in the final extracted product. The SEM images and EDX spectra demonstrated the microstructure of cellulose fibrils and their major elemental components as carbon and oxygen, respectively. The XRD data validated the crystalline (69.42%) nature of the cellulose. The various rheological attributes of cellulose suspension like the flow properties and dynamic rheological characteristics were examined at different pH, ionic strength and cellulose concentration. The cellulose suspensions exhibited shear thinning nature for all the pH, ionic concentration and cellulose concentrations. The change in viscoelastic behaviour of the cellulose suspension was noticed with the rise in storage modulus (G′) value with ionic concentration. The pH of the cellulose suspension had a significant impact on its viscoelastic properties due to the modifications in interfibrillar interactions of cellulose fibrils. The temperature ramp test showed that the G’ is independent of the heating of cellulose suspension from 20 °C to 80 °C. The creep and thixotropic recovery test revealed that upon removal of stress, there is the recovery of strain and viscosity up to a certain extent, which is a characteristic property of viscoelastic material.

SYST-17 GOLD NANOSTARS ENHANCE THE EFFICACY AND SAFETY OF LASER INTERSTITIAL THERAPY FOR THE TREATMENT OF INTRACRANIAL TUMORS

Abstract Laser interstitial thermal therapy (LITT) is a minimally-invasive technique for the treatment of intracranial tumors that uses a stereotactically-guided laser for ablation. Magnetic resonance thermal imaging is used to monitor ablation progress by measuring the cumulative heat energy exposure in both the tumor and the surrounding tissue to calculate thermal damage thresholds.Previous applications of GNS in laser ablation of tumors have studied extracranial tumors only and utilized externally administered near infrared radiation that cannot penetrate the cranial compartment. Herein, we present a novel platform for employing GNS in intracranial tumors. We developed GNS that exhibit maximum photothermal effects at the 1064 nm laser wavelength used in the FDA-approved clinical Neuroblate® LITT system. Monte Carlo simulations demonstrate that our GNS can accelerate and focus thermal energy distributions. Using ex vivo tumor phantom models, GNS-infused phantoms demonstrate more rapid heating, expanded ablation zones, and improved margin conformation, with surrounding areas exposed to lower temperatures than controls. In in vivo intracranial tumor models, we show that GNS selectively accumulate and are retained in CT2A glioma and B16F0 melanoma tumors at 24 and 72 hours post-injection. Using our in vivo heterotopic CT2A model, we demonstrate that systemically-delivered GNS dramatically augment laser ablation, with higher temperatures achieved in the tumor and more efficient temperature ramping. These results support the ability of GNS to optimize LITT for the treatment of intracranial tumors by improving the efficiency and safety of this platform.