Goodyear (United States)

Chain relaxation in melts of moderately entangled macromolecules presents the first signs of topological constraints that are commonly manifested in the rheology of long commercial-grade polymers. In this study, we employ multiscale molecular dynamics simulations to examine the relaxation characteristics of model polyisoprene (PI) melts through the transition from the Rouse regime to entangled systems. We probed the impact of molecular weight and stereochemistry and evaluated the accuracy of theory in modeling the end-to-end relaxation. Our results support that trans-PI dynamics is distinct, with entanglements forming at a lower degree of polymerization than other compositions due to differences in the characteristic ratio and packing of this polymer. For all moderately entangled systems, modeling the end-to-end relaxation with the original Likhtman–McLeish theory with contour-length fluctuations presents deviations from recorded data in both the early time and terminal regime. We propose numerical modifications that significantly improve the model for all of the systems studied without introducing additional parameters. Our approach allows accurate predictions for long macromolecules based on data from detailed simulations with moderately entangled polyisoprene systems.

BackgroundChronic rhinitis (CR) is characterized by refractory symptoms such as rhinorrhea, sneezing, nasal congestion, postnasal drip (PND), and cough. Most patients do not achieve lasting symptom relief with medical management.ObjectiveTo evaluate the long-term efficacy and safety of temperature-controlled radiofrequency treatment targeting posterior nasal nerves (PNNs) for CR.MethodsThis prospective, single-arm, open-label, multicenter study included patients aged 18–85 years across 19 centers in the United States and Germany. Outcome measures included reflective Total Nasal Symptom Score (rTNSS), PND and cough scores, and the Mini Rhinoconjunctivitis Quality of Life Questionnaire (MiniRQLQ). Outcomes, including adverse events, were reported through 3 years post-procedure.SettingAll procedures were performed in an outpatient office-based setting.ResultsOne hundred twenty-nine patients received treatment; 101 completed 3-year follow-up. The adjusted mean rTNSS Score improved from 7.8 (95% confidence interval [CI]: 7.5-8.1) at baseline to 3.2 (95% CI: 2.8-3.7) at 3 years (mean change: −4.5 [95% CI: −5.1 to −4.0]; P < .001). Rhinorrhea symptom scores improved from 2.6 to 1.2 (55.8% reduction). Compared to baseline, at 3 years, adjusted mean cough and PND scores declined from 1.3 to 0.4 (mean change: −0.9; P < .001, 69% reduction) and from 2.4 to 1.2 (mean change: −1.2; P < .001, 50% reduction), respectively. MiniRQLQ scores were significantly reduced from an adjusted mean of 3.0 (95% CI: 2.8-3.2) at baseline to 1.2 (95% CI: 1.0-1. 4) at 3-year follow-up; P < .001. No serious device- or procedure-related adverse events were reported.ConclusionA single temperature-controlled radiofrequency treatment of the PNN safely and effectively reduced CR symptoms, including cough and PND, improved quality of life, and decreased medication burden through a period of 3 years with no serious adverse events.

Crosslinking macromolecules is an important process that aims to modulate mechanical properties of elastomers and meet desired specifications based on the application sought. The impact of crosslinking density on rubber moduli has been well established by theory, experiments and computational studies. However, several reports imply a role for the length of the sulfide bond and the attachment location. In this study, we construct all-atom models of polyisoprene (PI) networks using equilibrated precursor melts and sulfide crosslinks of a specific chemical architecture. We first examine network characteristics which follow expectations based on our random crosslinking approach. We report the presence of a substantial number of intramolecular connections formed. Thermodynamics and microscopic dynamics of the resulting networks are also probed. Comparing systems with the same number of crosslinks, we find that local mobility is most decelerated in the presence of long quaternary connections. To resolve any impact on mechanical properties we resorted to extensive characterization of moduli via equilibrium (stress-stress fluctuations) and non-equilibrium processes (constant-rate and oscillatory deformations). Both equilibrium and non-equilibrium simulations (at times/frequencies accessible to our all-atom models) confirm that quaternary linkages provide for the highest moduli with linker length holding a secondary role during moderate deformations.

Crosslinking macromolecules is an important process that aims to modulate mechanical properties of elastomers and meet desired specifications based on the application sought. The impact of crosslinking density on rubber moduli has been well established by theory, experiments and computational studies. However, several reports imply a role for the length of the sulfide bond and the attachment location. The influence of the linker architecture on the dynamics and mechanical properties with the information from the detailed atomistic model will be helpful in tuning the design of elastomers with fillers. In this study, we construct numerous all-atom models of polyisoprene (PI) networks using well-equilibrated precursor melts and sulfide crosslinks of a specific chemical architecture. We examine network characteristics that follow expectations based on our random crosslinking approach and report the presence of a substantial number of intramolecular connections formed. Thermodynamics and microscopic dynamics of the resulting networks are also probed. Comparing systems at the same number of crosslinks, we find that local mobility is most decelerated in the presence of long quaternary connections. To resolve any impact on mechanical properties we resorted to extensive characterization of moduli via equilibrium (stress-stress fluctuations) and non-equilibrium processes (constant-rate and oscillatory deformations). At frequencies accessible to our all-atom models, simulations confirm that quaternary linkages provide for the highest moduli with linker length holding a secondary role during deformations.

Background/ObjectivesUnfortunately, not all metastatic castration resistant prostate cancer (mCRPC) patients receive available life-prolonging systemic therapies, emphasizing the need to optimize mCRPC treatment selections. Better guidelines are necessary to determine genetic testing in prostate cancer.Subjects/MethodsIn this two-part expert opinion-based guide, we provide an expert consensus opinion on the utilization of germline and somatic testing to detect HRR alterations in patients with mCRPC. This guide was developed by a multidisciplinary expert panel that convened in 2023–2024, including representatives from medical oncology, urology, radiation oncology, pathology, medical genomics, and basic science.Results/ConclusionWe argue for the widespread adoption of germline testing in all patients with prostate cancer and for somatic mutations testing in patients at the time of recurrent/metastatic disease. In this first part, we review how genomic testing is performed. We also review how to overcome certain barriers to integrate genetic and biomarker testing into clinical practice.

Through the analysis of the spatial correlations of local stress, we detect the propagation of long-ranged liquid-elasticity-mediated shear stress waves in polymeric and low-molecular weight liquids. The propagation of shear waves is effectively planar; i.e., σαβ propagates in the αβ plane. The autocorrelation functions of the local stress of a region are affected by both the relaxation of stress in that region and the propagation of stress from the region to the rest of the sample. However, due to the planar propagation of shear waves, the transfer of σαβ from those slices of the simulation box that are periodic in the αβ plane is negligible. This allows direct probing of the position-dependent local stress relaxation modulus of liquid in the vicinity of a confining surface. Published by the American Physical Society 2024

Merrigan, JJ, Stone, JD, Kraemer, WJ, Vatne, EA, Onate, J, and Hagen, JA. Female National Collegiate Athletic Association Division-I athlete injury prediction by vertical countermovement jump force-time metrics. J Strength Cond Res 38(4): 783-786, 2024-Vertical countermovement jump (CMJ) assessments on force plates have been purported to screen for musculoskeletal injury risk (MSKI) but with little scientific support. Thus, this study aimed to identify associations and noncontact lower-body injury predictability with CMJ force-time metrics in female athletes. The study entailed a retrospective analysis of routine injury and performance monitoring from 155 female National Collegiate Athletics Association Division I athletes. Noncontact lower-body injuries included in analysis were confirmed by medical staff, occurred during competition or training, resulted in time loss from training, and occurred within 3 months following CMJ testing (2 maximal effort, no arm swing, jumps on dual force plates). A total of 44 injuries occurred within 3 months following CMJ baseline testing and resulted in an average of 24.5 missed days from training. Those who sustained an injury were more likely to sustain another injury (15 of 44 injuries [33.1%]; odds ratio = 3.05 [95% CI = 1.31-6.99]). For every 1-unit increase from the mean in eccentric mean power and minimum eccentric force, there was a decrease in odds of sustaining a MSKI. Despite high overall model accuracy (85.6%), the receiving operating characteristic area under the curve (65.9%) was unacceptable and the true positive rate (recall) was 0.0%. Thus, no injuries in the testing data set were correctly classified by the logistic regression model with CMJ force-time metrics as predictors. Baseline CMJ assessment may not be useful for noncontact lower-body musculoskeletal injury screening or predictability in National Collegiate Athletics Association female athletes.

ABSTRACT Rubber engineering design analysis requires a fundamental understanding of the mechanical behavior of polymers, especially in their unvulcanized state. It necessitates the establishment of a three-dimensional constitutive material to account for the observed mechanical behavior. This law is required to produce realistic descriptions of the viscoelastic performance in a mathematically simple form that is easy to implement in engineering applications. This article describes the theory of the Tschoegl–Chang–Bloch time-dependent nonlinear viscoelastic constitutive law. The experimental verification of this law is provided under different deformation fields and multiple load steps. Laboratory test procedures to obtain the parameters required to describe the material under consideration are provided in detail. A recursive form of the constitutive law, suitable for finite element application, is derived and coded in the finite element commercial code Abaqus via the user subroutine UMAT. Comparisons between the experimental observations, the theoretical results, and the numerical data are drawn for simple test models examined under creep or shear relaxation conditions. The excellent agreements observed indicate the suitability of the governing law in analyzing viscoelastic problems of unvulcanized carbon black–filled rubbers.

Huanglongbing (HLB, citrus greening disease), the most destructive disease affecting citrus production, is primarily linked to the gram-negative, insect-vectored, phloem-inhabiting α-proteobacterium 'Candidatus Liberibacter asiaticus' (CLas). With no effective treatment available, management strategies have largely focused on the use of insecticides in addition to the destruction of infected trees, which are environmentally hazardous and cost-prohibitive for growers, respectively. A major limitation to combating HLB is the inability to isolate CLas in axenic culture, which hinders in vitro studies and creates a need for robust in situ CLas detection and visualization methods. The aim of this study was to investigate the efficacy of a nutritional program-based approach for HLB treatment, and to explore the effectiveness of an enhanced immunodetection method to detect CLas-infected tissues. To achieve this, four different biologically enhanced nutritional programs (bENPs; P1, P2, P3, and P4) were tested on CLas-infected citrus trees. Structured illumination microscopy preceded by a modified immunolabeling process and transmission electron microscopy were used to show treatment-dependent reduction of CLas cells in phloem tissues. No sieve pore plugging was seen in the leaves of P2 trees. This was accompanied by an 80% annual increase in fruit number per tree and 1,503 (611 upregulated and 892 downregulated) differentially expressed genes. These included an MLRQ subunit gene, UDP-glucose transferase, and genes associated with the alpha-amino linolenic acid metabolism pathway in P2 trees. Taken together, the results highlight a major role for bENPs as a viable, sustainable, and cost effective option for HLB management.

Access to the anterolateral pontine lesions can be achieved through the peritrigeminal and supratrigeminal safe entry zones using Kawase, retrosigmoid, or translabyrinthine approaches. However, these approaches entail shallow extensive dissection, tangential access, and compromise vestibulocochlear function. We aimed to investigate infratentorial presigmoid retrolabyrinthine approach to access pontine lesions through the peritrigeminal zone. We performed 10 presigmoid retrolabyrinthine suprameatal approach dissections in 5 cadaveric heads. Anatomic-radiological characteristics and variations were evaluated. Six morphometric parameters were measured and analyzed to predict surgical accessibility. The pontine infratrigeminal area was accessible in all patients. The mean exposed area of the anterolateral pontine surface was 98.95 cm 2 (±38.11 cm 2 ). The mean length of the exposed trigeminal nerve was 7.9 cm (±2.9 cm). Preoperative anatomic-radiological parameters may allow to select patients with favorable anatomy that offers appropriate surgical accessibility to the anterior pontine cavernoma through a presigmoid retrolabyrinthine corridor. Anterolateral pontine lesions can be accessed through a minimally invasive infratentorial presigmoid retrolabyrinthine approach by targeting the infratrigeminal safe entry zone. Further clinical studies should be conducted to evaluate the viability of this technique for treating these complex pathologies in real clinical settings.