Ball Model Research Articles

Hidden Integrality and Semirandom Robustness of SDP Relaxation for Sub-Gaussian Mixture Model

We consider the problem of estimating the discrete clustering structures under the sub-Gaussian mixture model. Our main results establish a hidden integrality property of a semidefinite programming (SDP) relaxation for this problem: while the optimal solution to the SDP is not integer-valued in general, its estimation error can be upper bounded by that of an idealized integer program. The error of the integer program, and hence that of the SDP, are further shown to decay exponentially in the signal-to-noise ratio. In addition, we show that the SDP relaxation is robust under the semirandom setting in which an adversary can modify the data generated from the mixture model. In particular, we generalize the hidden integrality property to the semirandom model and thereby show that SDP achieves the optimal error bound in this setting. These results together highlight the “global-to-local” mechanism that drives the performance of the SDP relaxation. To the best of our knowledge, our result is the first exponentially decaying error bound for convex relaxations of mixture models. A corollary of our results shows that in certain regimes, the SDP solutions are in fact integral and exact. More generally, our results establish sufficient conditions for the SDP to correctly recover the cluster memberships of [Formula: see text] fraction of the points for any [Formula: see text]. As a special case, we show that under the [Formula: see text]-dimensional stochastic ball model, SDP achieves nontrivial (sometimes exact) recovery when the center separation is as small as [Formula: see text], which improves upon previous exact recovery results that require constant separation.

The Hardy–Schrödinger operator on the Poincaré ball: Compactness, multiplicity, and stability of the Pohozaev obstruction

Let Ω be a smooth relatively compact domain containing zero in the Poincaré ball model of the Hyperbolic space Bn (n≥3) and let −ΔBn be the Laplace-Beltrami operator on Bn. We consider problems of non-existence, existence, and multiplicity of variational solutions for the borderline Dirichlet problem,(1){−ΔBnu−γV2u−λu=V2⋆(s)|u|2⋆(s)−2u in Ωu=0 on ∂Ω, where γ<(n−2)24, 0<s<2, 2⋆(s):=2(n−s)n−2 being the corresponding critical Sobolev exponent, while V2 (resp., V2⋆(s)) is a Hardy-type potential (resp., Hardy-Sobolev weight) that is invariant under hyperbolic scaling and which behaves like 1r2 (resp. 1rs) at the origin. The bulk of this paper is a sharp blow-up analysis that we perform on certain approximate solutions of (1) with bounded but arbitrary high energies. When these approximate solutions are positive, our analysis leads to improvements of results in [5] regarding positive ground state solutions for (1), as we show that they exist whenever n≥4, 0≤γ≤(n−2)24−1 and λ>0. The latter result also holds true for n≥3 and γ>(n−2)24−1 provided the domain has a positive “hyperbolic mass”. On the other hand, the same analysis yields that if γ>(n−2)24−1 and the mass is non vanishing, then there is a surprising stability of regimes where no variational positive solution exists. As for higher energy solutions to (1), we show that there are infinitely many of them provided n≥5, γ<(n−2)24−4 and λ>n−2n−4(n(n−4)4−γ).

Performance Analysis of Opportunistic Beam Splitting NOMA in Millimeter Wave Networks

Applying non-orthogonal multiple access (NOMA) in millimeter-wave (mmWave) networks has the potential to significantly enhance the spectral efficiency. In this paper, we propose an opportunistic beam-splitting NOMA scheme to fully exploit the antenna array gain in downlink mmWave networks, where single- and double-beam NOMA transmissions are dynamically enabled according to the spatial angle difference between the paired NOMA users, thereby enhancing the flexibility of applying NOMA in mmWave networks. The base station with a single radio frequency chain implements the double-beam NOMA transmission by adopting the beam-splitting technique. We develop a unified theoretical performance analysis framework for the proposed scheme, while taking into account the spatially random users, link blockage model, and general distance-based user pairing strategy. By using tools from stochastic geometry, we derive the exact expressions of the coverage probability and the sum rate of the proposed scheme under both the LoS exponential and ball models. We further derive the corresponding upper bound to simplify the analytical expressions. Simulations validate the theoretical analysis and demonstrate the performance gains of the proposed scheme in terms of the coverage probability and sum rate over the conventional single-beam NOMA and orthogonal multiple access (OMA) schemes.

Biophysical compartment models for single-shell diffusion MRI in the human brain: a model fitting comparison

Clinically oriented studies commonly acquire diffusion MRI (dMRI) data with a single non-zero b-value (i.e. single-shell) and diffusion weighting of b = 1000 s mm−2. To produce microstructural parameter maps, the tensor model is usually used, despite known limitations. Although compartment models have demonstrated improved fits in multi-shell dMRI data, they are rarely used for single-shell parameter maps, where their effectiveness is unclear from the literature. Here, various compartment models combining isotropic balls and symmetric tensors were fitted to single-shell dMRI data to investigate model fitting optimization and extract the most information possible. Full testing was performed in 5 subjects, and 3 subjects with multi-shell data were included for comparison. The results were tested and confirmed in a further 50 subjects. The Markov chain Monte Carlo (MCMC) model fitting technique outperformed non-linear least squares. Using MCMC, the 2-fibre-orientation mono-exponential ball and stick model () provided artifact-free, stable results, in little processing time. The analogous ball and zeppelin model () also produced stable, low-noise parameter maps, though it required much greater computing resources (50 000 burn-in steps). In single-shell data, the gamma-distributed diffusivity ball and stick model () underperformed relative to other models, despite being an often-used software default. It produced artifacts in the diffusivity maps even with extremely long processing times. Neither increased diffusion weighting nor a greater number of gradient orientations improved fits. In white matter (WM), the tensor produced the best fit as measured by Bayesian information criterion. This result contrasts with studies using multi-shell data. However, in crossing fibre regions the tensor confounded geometric effects with fractional anisotropy (FA): the planar/linear WM FA ratio was 49%, while and retained 76% and 83% of restricted fraction, respectively. As a result, the and models are strong candidates to optimize information extraction from single-shell dMRI studies.

Meso fracture characteristics of granite and instability evolution law of surrounding rock in deep cavern

In order to analyze the influence of meso-structure and meso-parameters on deep granite characteristics, a construction method of variable radius proportional clump model was proposed with particle flow method. The clump particle flow structure was constructed which suited the mechanical characteristics of granite. The deep cavern numerical calculation model of gradual particle density was constructed using the variable radius proportional clump model construction method, and the macroscopic fracture law of deep cavern surrounding rock was analyzed. The results show that meso parameters have lower effects on the compressive and tensile ratios of particle structures in the ball and clump models. It is also found that clump structure is greatly influenced by particle proportion and size while ball model is only slightly influenced by particle size. Furthermore, the compressive and tensile strength curves and fracture modes of numerical simulations and laboratory tests are in good agreement. In addition, the calculated results of the tunnel after simulated excavation are very close to the engineering practice. There are obvious shear failure areas on the right vault and left wall of the tunnel, and the shape and depth of the fracture area are basically the same.

Fractal characteristics of a worn wall and the influence on the particle-wall collisions

A new particle-wall collision model is proposed to analyse the random rebound process of particles after collision with a rough wall. The new model includes two parts. First, the wear caused by particle collisions and the self-similarity of the wall microstructure are considered. The topography of a rough wall is constructed using fractal theory combined with an empirical erosion formula. Second, a return-to-subdivision method is used to determine the contact point between the particle and wall. The hard ball model is used to analyse the motion state of the rebound particles. The present model is numerically implemented through the Monte Carlo method and validated by comparison with the experimental data available in the literature. The possible reasons for the deviation between the predicted and measured results are presented. In addition, the compatibility of the present model with classical models is discussed in detail.

Fusion Dynamics of Hybrid Cell-Microparticle Aggregates: A Jelly Pearl Model.

We study the fusion of homogeneous cell aggregates and of hybrid aggregates combining cells and microparticles. In all cases, we find that the contact area does not vary linearly over time, as observed for liquid drops, but rather it follows a power law in t2/3. This result is interpreted by generalizing the fusion model of soft viscoelastic solid balls to viscoelastic liquid balls, akin to jelly pearls. We also explore the asymmetric fusion between a homogeneous aggregate and a hybrid aggregate. This latter experiment allows the determination of the self-diffusion coefficient of the cells in a tissue by following the spatial distribution of internalized particles in the cells.

Performance Modeling and Analysis of Base Station Cooperation for Cellular-Connected UAV Networks

This paper studies the performance of base station (BS) cooperation for the downlink transmission of an unmanned aerial vehicle (UAV) in a cellular-connected UAV network. Performance models are derived for investigating the downlink transmission performance of a UAV with BS cooperation in terms of coverage probability and achievable throughput. In deriving the performance models, we consider two UAV distribution cases: general case and worst case, in which the locations of UAVs follow different distributions. Meanwhile, we introduce a line-of-sight (LoS) ball model to describe the LoS probability of the downlink channel between a BS and a UAV, and show that it has a good approximation to the ITU LoS model, and can largely simplify the derivation of the performance models. Monte Carlo simulation results are shown to validate the derived performance models. The impacts of major network parameters on the downlink transmission performance are investigated through numerical results. The performance models can be used to provide theoretical guidance for the design of a BS cooperation strategy.

Dynamic stiffness and vibration analysis model of angular contact ball bearing considering vibration and friction state variation

Force and thermal effect are dominant in giving rise to variation of bearing dynamic stiffness and vibration. On the basis of test and theoretical analysis, the dynamic stiffness and vibration model of angle contact ball bearing considering vibration and friction state variation is established. Firstly, based on the quasi-statics of bearing and hydrodynamic lubrication theory, the motion and force relation between each parts are determined by considering the force and thermal effect. Secondly, the friction power consumption of bearing is calculated adopting integrated method, besides, the conduction heat resistance and convection heat resistance in the bearing system are achieved. A steady-state temperature calculation model of angle contact ball bearing-shaft-house system is built based on thermal network method. Finally, the dynamic stiffness and vibration model of angular contact ball bearing including the thermal-solid coupling effect is obtained, which is employed to realize the theoretical analysis of bearing dynamic stiffness and vibration, its accuracy is verified through typical test results. The calculation results shows that there is a good agreement between house test temperature and calculation temperature. The evolution rule of contact deformation and contact stiffness between ball and outer/inner ring over the whole life under excessive preload is the same. So does the oil film thickness and oil film stiffness. However, the curve shape and amplitude of contact angular between ball and outer/inner ring over the whole life is different. Bearing radial stiffness value has a more significant change than axial stiffness value, both of them represent an overall upward tendency. The radial clearance holds a negative correlation with house temperature, however, the radial displacement has a positive correlation with house temperature. The evolvement curve of contact angular affected by various preload and speed is opposite. The contact load between ball and outer/inner ring has the same trend influenced by preload and speed with EHL. The variation of preload has bigger effect on temperature rise than speed change. The oil film has little influence on contact angular, contact load and temperature under dry-lubricated or lightly lubricated condition.

Selective transport of water molecules through interlayer spaces in graphite

Interlayer space in graphite is impermeable to ions and molecules, including protons. Its controlled expansion would find several applications in desalination, gas purification, high-density batteries, etc. In the past, metal intercalation has been used to modify graphitic interlayer spaces; however, resultant intercalation compounds are unstable in water. Here, we successfully expanded graphite interlayer spaces by intercalating aqueous KCl ions electrochemically. Our spectroscopy studies provide clear evidence for cation-π interactions explaining the stability of the devices, though weak anion-π interactions were also detectable. The water conductivity shows several orders of enhancement when compared to unintercalated graphite. Water evaporation experiments further confirm the high permeation rate. There is weak ion permeation through interlayer spaces, up to the highest chloride concentration of 1 M, an indication of sterically limited transport. In these very few transported ions, we observe hydration energy-dependent selectivity between salt ions. These strongly suggest a soft ball model of steric exclusion, which is rarely reported. These findings improve our understanding of molecular and ionic transport at the atomic scale.

Analytical solution of a linear nonlocal Poisson-Boltzmann equation with multiple charges in a spherical solute region surrounded by a water spherical shell.

In this paper, an analytical solution of a linear nonlocal Poisson-Boltzmann equation (NPBE) test model with multiple charges in a spherical solute region surrounded by a water spherical shell is derived as a single series of Legendre polynomials and modified spherical Bessel functions. The classic Kirkwood ball model is then shown to be a special case of the NPBE test model so that its analytical solution is regained from a double series of associated Legendre polynomials (derived by Kirkwood in 1934) to a new single series of Legendre polynomials, sharply reducing its computational cost. As an application of these series solutions, a comparison study is done to demonstrate the differences between the Kirkwood and NPBE test models.

Ball and Stick Fun Model Kit for Stem Education

The majority of students are expected to have strong critical thinking and problem-solving abilities in 21st-century learning. Students can form mental habits that will help them succeed in any subject due to the emphasis on logical thought processes and problem-solving. The list of science, technology, Engineering, and mathematics (STEM) subjects is quite vast and chemistry is one of them. The STEM curriculum pushes students to think critically and develop original answers. Chemistry subject is believed as a major subject in the science field, however, in Malaysia, it is also deemed as one of the most challenging subjects. Crystal and chemical bonding topic are included in the Sijil Pelajaran Malaysia (SPM), Sijil Tinggi Persekolahan Malaysia (STPM), Diploma and Degree syllabus. In chemistry, the topic of crystal structure and chemical bonding is commonly taught via slide presentations explaining the theories. Thus, this kit introduces a new teaching method where students need to produce the chemical bonding or crystal structure by using the “Ball and Stick” model. The coloured balls made from styrofoam represent atoms, while a set of sticks represent the bonds that hold them together. It is a special set of tinker kits to represent how molecules look. This kit box has been sold at a fixed price of RM19.90 and it contains 200 pieces of molecular model kit, including 70 atoms (ball), 100 bonds (stick) and 30 parts for lone pair. It comes with CD-ROM for instruction, notes and exercises hence providing a fun learning tool kit for students from secondary to university level. The kits can be dismantled and rebuilt or can be used for display or as a model for teaching specific crystallographic or structural concepts. The different coloured balls represent atoms of different elements. A survey has been conducted on a small group of diploma students and 100% of students agree that this kit is both entertaining and useful in gaining insight into the subject matter.

The effect of attachment types and implant level on the stress distribution in a mandibular overdenture: a 3D Finite Element Analysis

Objective: The objective of this study was to evaluate the stress distribution in bone-surrounding implants placedin different levels in a mandibular overdenture. Material and Methods: A Computerized Tomography (CT) scanof an edentulous mandible was used to generate the models. Two implants with an internal connection wereplaced perpendicular to the occlusal plane in the Canine sites of the mandible. The implant in the left side wasplaced 1mm higher than the other side. Dolder bar and ball attachments were designed. Loading was performedby clenching the teeth with reconstruction of the muscles. In the anterior loading condition, force was appliedto the central incisors and in the posterior loading conditions, it was applied to the molars and premolars. Thenthe Maximum Principal Stresses in the peri implant bone was evaluated with finite element analysis. Results:In both models, the highest stress values were recorded in the cortical bone surrounding the higher implantexcept in the ball model with unilateral load application on the right side (64.7 MPa). In almost all loadingconditions the stress value differences in models with bar and ball attachments were low. Only in the anteriorloading condition, the stress magnitude was higher in two implants of the ball model (60.5 MPa in the left sideand 21 MPa in the right side) compared to the bar model (54.5 MPa in the left side and 17.5 MPa in the rightside). Conclusion: The stress concentration did not affected considerably by the attachment system. High stressvalues were found adjacent the implant with a higher level. To reduce the amount of stress, bilateral balanceocclusion should be considered. KEYWORDSStress; Finite element analysis; Overdenture; Dental implants.

A Study of Bound Behavior in Table Tennis Ball

In this study, we have developed a four-roller type table tennis machine that can shoot balls such as a top, back, side and gyro rotations with high speed and spin rate, which are difficult to shoot with existing table tennis machines. Using the developed machine, the table tennis ball was bounced on the table tennis table, and it was investigated the dynamic behavior of the ball before and after the collision. In addition, collision and rebound simulations were performed using the finite element models of a table tennis ball and table. From the results of the bound experiment and simulation, it was found that the coefficient of restitution, flight trajectory and spin rate after the bound change depending on the spin types and the value of the coefficient of friction between the ball and table. In addition, these values were significantly different between the side and gyro spins.

Assessment of brain injury biomechanics in soccer heading using finite element analysis

This study presents an in silico finite element (FE) model-based biomechanical analysis of brain injury metrics and associated risks of a soccer ball impact to the head for aware and unaware athletes, considering ball impact velocity and direction. The analysis presented herein implements a validated soccer ball and 50th percentile human head computational FE model for quantifying traumatic brain injury (TBI) metrics. The brain's mechanical properties are designated using a viscoelastic-viscoplastic constitutive material model for the white and gray matter within the human head FE model. FE results show a dynamic human head-soccer ball peak contact area of approximately seven times greater than those documented for helmet-to-helmet hits in American Football. Due to the deformable nature of the soccer ball, the impact dynamics are unique depending on the location and velocity of impact. TBI injury risks also depend on the location of impact and the impact velocity. Impacts to the rear (BrIC:0.48, HIC15:180.7), side (BrIC:0.52, HIC15:176.5), and front (BrIC:0.37, HIC15:129.0) are associated with the highest injury risks. Furthermore, the FE results indicate when an athlete is aware of an incoming ball, HIC15-based Abbreviated Injury Scale 1 (AIS 1) injury risks for the front, side, and rear impacts decrease from 10.5%, 18.5%, and 19.3%, respectively, to approximately 1% in front and side impacts and under 6% in a rear impact. Lastly, the unique contact area between the head and soccer ball produces pressure gradients in the ball that translate into distinguishable stress waves in the skull and the cerebral cortex. Statement of significanceMild traumatic brain injuries (mTBI) are a worrisome aspect of participation in most sports due to difficulties in their diagnosis in competitions and the potential of long-term neurological defects. These types of injuries are not well understood for athletes playing soccer, specifically pertaining to the risks of heading a soccer ball. Studies are warranted which investigate impacts in this game to improve current knowledge. Our computational study uses finite element modeling to investigate contact between a player's head and the soccer ball. The results of this study present potential injury mechanisms and risks caused by this contact interaction to contribute to the current understanding of brain injuries in soccer and the promotion of athlete safety.

Boundedness of Solutions for a Bouncing Ball Model with Quasiperiodic Potential

Boundedness of Solutions for a Bouncing Ball Model with Quasiperiodic Potential

Study on Influencing Factors of Helicopter Brownout Evolution Based on CFD-DEM

The gas-solid two-phase flow model is constructed based on the Euler-Lagrangian framework. The SST k−ω two-equation turbulence model and the soft ball model are coupled by computational fluid dynamics (CFD) and a discrete element model (DEM). Brownout is then simulated by the above method with sliding mesh. As the calculation examples show, the simulations and experiments of the Lynx rotor and the Caradonna–Tung rotor are compared. The coupling method is verified through calculation of the rotor lift coefficient, blade section pressure coefficient and tip vortex shedding position. The results show that when the helicopter is hovering at a height of 0.52R from the ground, it will cause brownout and the pilot’s vision will be obscured by sand. When the hovering height is 1R, the phenomenon of brownout is not serious. The movement speed of most sand dust is about 12 m/s, and the height of the sand dust from the ground will gradually increase over time. Large particles of sand are more difficult to be entrained into the air than the small particles, and the particles with a radius of 50 um are basically accumulated on the ground. Moreover, the slotted-Tip rotor has an effect on restraining brownout.

Abstract P237: PRT2527 is a potent and selective CDK9 inhibitor that demonstrates anti-cancer activity in preclinical models of hematological malignancies and solid tumors with MYC amplification

Abstract Cyclin-dependent kinase 9 (CDK9) is a master regulator of transcription that controls paused RNA polymerase II (RNAP2) release through phosphorylation of its carboxy-terminal domain, resulting in productive transcription elongation. CDK9 has been extensively studied as a potential target for cancer therapy in “transcriptionally addicted” tumors as transient inhibition of CDK9 primarily depletes proteins with short half-lives, such as the oncogenes MCL1 and MYC, making CDK9 a promising target in cancer. Here we show that PRT2527 is a potent and highly selective CDK9 inhibitor with moderate to high clearance that achieves optimal temporal target engagement and exhibits potent in vitro and in vivo activities. PRT2527 inhibited CDK9 enzymatic activity with an IC50 of 0.98 nM in a biochemical assay and showed high selectivity in a panel of kinases when tested at physiologically relevant 1 mM ATP concentration. In vitro, PRT2527 inhibited phosphorylation of Ser2RNAP2 in NCI-H929 cells with an IC50 of 54 nM, and an IC50 of 198 nM in a plasma assay to adjust for human plasma protein binding. Transient treatment of cells with PRT2527 inhibited pSer2RNAP2, depleted MCL1 and MYC proteins, and activated cleaved caspase-3 (CC3) in a concentration-dependent manner. In a proteomic profiling study, MCL1 was identified as one of the major down-regulated proteins following PRT2527 treatment. In a panel of hematological cancer cell lines representing B- and T-ALL, AML, and non-Hodgkin’s lymphoma (NHL), as well as subsets of sarcoma, prostate, adenoid cystic carcinoma (ACC), and non-small cell lung cancer (NSCLC) cell lines, PRT2527 treatment consistently led to a potent, concentration-dependent inhibition of proliferation. In a pharmacokinetic/pharmacodynamic (PK/PD) study, intravenous (IV) administration of PRT2527 achieved transient target engagement, depletion of MCL1 and MYC proteins, and induction of apoptosis in tumor tissue. This PK/PD correlation was successfully translated into in vivo efficacy in multiple models. Once weekly dosing of PRT2527 was well-tolerated and significantly inhibited tumor growth in various AML CDX models and induced tumor regressions in double-hit and triple-hit diffuse large B-cell lymphoma (DLBCL) CDX and PDX models carrying the MYC translocation. Combining PRT2527 with venetoclax achieved complete tumor regressions in a venetoclax resistant OCI-AML3 model. PRT2527 demonstrated potent ex vivo activity in PDX models of B-ALL and T-ALL, as well as various solid tumor PDX models with high levels of MYC amplification and overexpression, including pancreatic carcinoma, gastric and gastroesophageal carcinomas, NSCLC, and sarcoma. In vivo efficacy studies with once weekly IV administration of PRT2527 confirmed significant tumor growth inhibition in select MYC-amplified solid tumor PDX models. Taken together, this preclinical characterization supports the advancement of PRT2527 into clinical studies for transcriptionally addicted hematological malignancies and solid tumors with MYC amplification and/or dysregulation. Citation Format: Yang W. Zhang, Liang Lu, Min Wang, Dave Rominger, Stefan Ruepp, Kirsten Gallagher, William Gowen-MacDonald, Chaofeng Dai, Miles Cowart, Andrew Combs, Bruce Ruggeri, Peggy Scherle, Kris Vaddi. PRT2527 is a potent and selective CDK9 inhibitor that demonstrates anti-cancer activity in preclinical models of hematological malignancies and solid tumors with MYC amplification [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P237.

In vitro and in vivo effects of AVA4746, a novel competitive antagonist of the ligand binding of VLA-4, in B-cell acute lymphoblastic leukemia.

Treatment of resistant or recurrent acute lymphoblastic leukemia (ALL) remains a challenge. It was previously demonstrated that the adhesion molecule integrin α4, referred to hereafter as α4, mediates the cell adhesion-mediated drug resistance (CAM-DR) of B-cell ALL by binding to vascular cell adhesion molecule-1 (VCAM-1) on bone marrow stroma. In addition, it was previously observed that the blockade of α4 with natalizumab or inhibition using the small molecule antagonist TBC3486 sensitized relapsed ALL cells to chemotherapy. However, α4-targeted therapy is not clinically available for the treatment of leukemia to date. In the present study, the use of a novel non-peptidic small molecule integrin α4 antagonist, AVA4746, as a potential new approach to combat drug-resistant B-ALL was explored. An in vitro co-culture = model of primary B-ALL cells and an in vivo xenograft model of patient-derived B-ALL cells were utilized for evaluation of AVA4746. VLA-4 conformation activation, cell adhesion/de-adhesion, endothelial tube formation, in vivo leukemia cell mobilization and survival assays were performed. AVA4746 exhibited high affinity for binding to B-ALL cells, where it also efficiently blocked ligand-binding to VCAM-1. In addition, AVA4746 caused the functional de-adhesion of primary B-ALL cells from VCAM-1. Inhibition of α4 using AVA4746 also prevented angiogenesis in vitro and when applied in combination with chemotherapy consisting of Vincristine, Dexamethasone and L-asparaginase, it prolonged the survival of ~33% of the mice in an in vivo xenograft model of B-ALL. These data implicate the potential of targeting the α4-VCAM-1 interaction using AVA4746 for the treatment of drug-resistant B-lineage ALL.

EFFECTS OF TEMPERATURE IN DEGRADATION KINETICS OF ANTHOCYANIN FROM JAMUN FRUIT (Eugenia jambolana) USING THE ARRHENIUS, EYRING AND BALL MODELS

Anthocyanins are flavonoids found in fruits and vegetables, ranging from red to violet and blue, which are shown to be a potential substitute for artificial colors, especially in food. Due to its thermal instability, this work had as objective to establish the kinetic and thermodynamic parameters that describe the thermal degradation of the anthocyanins from jamun fruit between 50 and 80 ° C using the Arrhenius, Eyring and Ball models. The thermal degradation process of the anthocyanins followed a model of first-order kinetics and the three models correlated the temperature to the degradative process coefficients of determination between 0.939 and 0.960. The activation energy was 93.383 kJ mol -1 and, thermodynamically, the values of ΔH, ΔS and ΔG did not differ when using the Arrhenius or Eyring approaches, allowing, according to both, to characterize the degradation reaction as endothermic, non-spontaneous and with the transition state with less structural freedom than the regents. According to the Ball model, the temperature range z was 27.03°C.