A theoretical insight into phonon heat transport in graphene/biphenylene superlattice nanoribbons: a molecular dynamic study.

Manipulating the thermal conductivity of nanomaterials is an efficacious approach to fabricate tailor-made nanodevices for thermoelectric applications. To this end, superlattice nanostructures can be used to achieve minimal thermal conductivity for the employed nanomaterials. Two-dimensional biphenylene is a recently-synthesized sp2-hybridized allotrope of carbon atoms that can be employed in superlattice nanostructures and therefore further investigation in this context is due. In this study, we first determined the thermal conductivity of biphenylene at 142.8 W mK-1which is significantly lower than that of graphene. As a second step, we studied the effect of the superlattice period (lp) on thermal conductivities of the employed graphene/biphenylene superlattice nanoribbons, using molecular dynamics simulations. We calculated a minimum thermal conductivity of 105.5 W mK-1atlp= 5.066 nm which indicates an achieved thermal conductivity reduction of approximately 97% and 26% when compared to pristine graphene and biphenylene, respectively. This superlattice period denotes the phonon coherent length at which the wave-like behavior of phonons starts prevailing over the particle-like behavior. Finally, the effects of temperature and temperature gradient on the thermal conductivity of superlattice were also investigated.

Graphene-carbon nitride interface-geometry effectson thermal rectification: A molecular dynamicssimulation.

We apply the non-equilibrium molecular dynamics approach (NEMD) to study thermal rectification in a hybrid graphene-carbon nitride system (G - C3N) under a series of positive and negative temperature gradients with varying interface geometries. In this study, we investigate the effects of a) temperature differences, (∆T), between the two employed baths, b) mediainterface geometry, and c) sample size, on thermal rectification. Our simulation results portray a sigmoid relation between thermal rectification and temperature difference, with a sample-size depending upper asymptote occurring at generally large temperature differences. The achieved thermal rectification values are significant and go up to around 120% for ∆T = 150 K. Furthermore, the consideration of varying media-interface geometries yields a non-negligible effect on thermal rectification and highlights areas for further investigation. Finally, calculations of Kapitza resistance at the G - C3N interface are performed for assisting us in the understanding of interface-geometry effects on thermal rectification.

A hybrid fluorescent nanofiber membrane integrated with microfluidic chips towards lung-on-a-chip applications.

Here, we report a fluorescent electrospun nanofiber membrane for integration into microfluidic devices towards lung-on-a-chip applications complemented with the results of computational fluid dynamics modelling. A proposed hybrid poly(ε-caprolactone) (PCL)-collagen membrane was developed, characterized, tested, and integrated into a prototype microfluidic chip for biocompatibility studies. The resulting membrane has a thickness of approximately 10 µm, can be adjusted for appropriate porosity, and offers excellent biocompatibility for mimicry of a basement membrane to be used in lung-on-a-chip device applications. Several membrane variations were synthesized and evaluated using SEM, FTIR, AFM, and high-resolution confocal fluorescence microscopy. A sample microfluidic chip made of cyclic olefin copolymer and polydimethylsiloxane was built and integrated with the developed PCL-collagen membrane for on-chip cell culture visualisation and biocompatibility studies. The sample chip design was modelled to determine the optimal fluidic conditions for using the membrane in the chip under fluidic conditions for future studies. The integration of the proposed membrane into microfluidic devices represents a novel strategy for improving lung-on-a-chip applications which can enhance laboratory recapitulation of the lung microenvironment.

Thermal rectification in novel two-dimensional hybrid graphene/BCN sheets: A molecular dynamics simulation.

The graphene-like monolayer of carbon, boron and nitrogen that maintains the native hexagonal atomic lattice (BCN), is a novel semiconductor with special thermal properties. Herein, with the aid of a non-equilibrium molecular dynamics approach (NEMD), we study phonon thermal rectification in a hybrid system of pure graphene and BCN (G-BCN) in various configurations under a series of positive and negative temperature gradients. We begin by investigating the relation of thermal rectification to sample's mean temperature, T, and the imposed temperature difference, ΔT, between the two heat baths at its ends. We then move to explore the effect of varying strain levels of our sample on thermal rectification, followed by Kapitza resistance calculations at the G-BCN interface, which shed light on the interface effects on thermal rectification. Our simulation results reveal a BCN-configuration-dependent behavior of thermal rectification. Finally, the underlying mechanism leading to a preferred direction for phonons is studied using phonon density of states (DOS) on both sides of the G-BCN interface.

Design, Simulation, and Evaluation of Polymer-Based Microfluidic Devices via Computational Fluid Dynamics and Cell Culture "On-Chip".

Organ-on-a-chip (OoC) technology has experienced exponential growth driven by the need for a better understanding of in-organ processes and the development of novel approaches. This paper investigates and compares the flow behavior and filling characteristics of two microfluidic liver-on-a-chip devices using Computational Fluid Dynamics (CFD) analysis and experimental cell culture growth based on the Huh7 cell line. The conducted computational analyses for the two chips showed that the elliptical chamber chip proposed herein offers improved flow and filling characteristics in comparison with the previously presented circular chamber chip. Huh7 hepatoma cells were cultured in the microfluidic devices for 24 h under static fluidic conditions and for 24 h with a flow rate of 3 µL·min-1. Biocompatibility, continuous flow, and biomarker studies showed cell attachment in the chips, confirming the cell viability and their consistent cell growth. The study successfully analyzed the fluid flow behavior, filling characteristics, and biocompatibility of liver-on-a-chip prototype devices, providing valuable insights to improve design and performance and advance alternative methods of in vitro testing.

An Evaluation of a Mobile App for Chronic Low Back Pain Management: Prospective Pilot Study.

BACKGROUND: Chronic low back pain is challenging to manage due to multidisciplinary considerations. It has substantial socioeconomic impacts and cannot be simply treated with pharmacotherapy, nonsurgical intervention, or spine surgery. Medical consensus recommends optimizing conservative self-management therapies (eg, home exercise, wellness strategies, yoga, etc) as first-line treatment options for chronic low back pain. However, access to these modalities is often limited and secondary to cost, convenience, and ease of use. Mobile health apps have emerged as a cost-effective and accessible option for chronic low back pain self-management. Established in-person pain programs can provide the structure for an optimal mobile app adaptation. PainNavigator (PainNavigator, Inc) is an example of a mobile app that is based on an Ascension-Illinois group-based pain program-Pain Rehabilitation Outpatient-Camp. OBJECTIVE: This was a prospective pilot clinical trial that evaluated the PainNavigator platform's utility in low back pain management to inform future trial development. METHODS: A total of 75 participants who used PainNavigator were studied. Pain, Enjoyment, and General Activity (PEG-3) scale scores and scores from a brief anxiety and depression scale based on the Patient Health Questionnaire-4 (PHQ-4) were obtained at baseline and following program completion. The PEG-3 total score was used, in addition to individual items-Average Pain, Pain Effect on Enjoyment, and Pain Effect on Activity. The PHQ-4 total score was also used, in addition to other individual items, including Felt Depressed, Loss of Interest, Felt Anxious, and Difficult to Control Worry. Paired sample t tests (2-tailed) compared mean differences in scores from before and after participants received the intervention. RESULTS: The analysis found that PEG-3 (n=27) and PHQ-4 (n=27) total scores were significantly lower upon the completion of PainNavigator (P<.001 and P=.001, respectively). The findings showed a 36% reduction in PEG-3 total scores, a 40% reduction in pain intensity, and a 40% reduction in PHQ-4 total scores. Scores for individual PEG-3 scale and PHQ-4 items also significantly decreased. All PEG-3 measures had large effect sizes. The PHQ-4 total score and Difficult to Control Worry item had large effect sizes, while the other three measures had medium effect sizes. CONCLUSIONS: These findings show that PainNavigator has clinical significance in managing chronic low back pain and can be easily utilized to improve patient care. All PEG-3 scale and PHQ-4 measures significantly improved following the use of the platform, supporting the multidimensional, biopsychosocial approach to low back pain management. Differences in effect sizes may inform quality improvement investigations, such as optimizing features that impact measures with only medium effect sizes. This feasibility study demonstrates an effective protocol, and it will inform future, more extensive randomized controlled trials.

Heat transfer through hydrogenated graphene superlattice nanoribbons: a computational study.

Optimization of thermal conductivity of nanomaterials enables the fabrication of tailor-made nanodevices for thermoelectric applications. Superlattice nanostructures are correspondingly introduced to minimize the thermal conductivity of nanomaterials. Herein we computationally estimate the effect of total length and superlattice period ([Formula: see text]) on the thermal conductivity of graphene/graphane superlattice nanoribbons using molecular dynamics simulation. The intrinsic thermal conductivity ([Formula: see text]) is demonstrated to be dependent on [Formula: see text]. The [Formula: see text] of the superlattice, nanoribbons decreased by approximately 96% and 88% compared to that of pristine graphene and graphane, respectively. By modifying the overall length of the developed structure, we identified the ballistic-diffusive transition regime at 120 nm. Further study of the superlattice periods yielded a minimal thermal conductivity value of 144 W m-1 k-1 at [Formula: see text] = 3.4 nm. This superlattice characteristic is connected to the phonon coherent length, specifically, the length of the turning point at which the wave-like behavior of phonons starts to dominate the particle-like behavior. Our results highlight a roadmap for thermal conductivity value control via appropriate adjustments of the superlattice period.

Crosslinking Multilayer Graphene by Gas Cluster Ion Bombardment.

In this paper, we demonstrate a new, highly efficient method of crosslinking multilayer graphene, and create nanopores in it by its irradiation with low-energy argon cluster ions. Irradiation was performed by argon cluster ions with an acceleration energy E ≈ 30 keV, and total fluence of argon cluster ions ranging from 1 × 109 to 1 × 1014 ions/cm2. The results of the bombardment were observed by the direct examination of traces of argon-cluster penetration in multilayer graphene, using high-resolution transmission electron microscopy. Further image processing revealed an average pore diameter of approximately 3 nm, with the predominant size corresponding to 2 nm. We anticipate that a controlled cross-linking process in multilayer graphene can be achieved by appropriately varying irradiation energy, dose, and type of clusters. We believe that this method is very promising for modulating the properties of multilayer graphene, and opens new possibilities for creating three-dimensional nanomaterials.

Self-estimation of phenylketonuria patients on therapeutic diet. Psychological support.

Objectives Self-esteem is the degree to which the qualities and characteristics contained in one's self-concept are perceived to be positive. The aim of this study was to evaluate the self-esteem scores in phenylketonuria (PKU) patients on "strict", "loos" and "off diet". Sixty PKU patients were divided in three equal groups. Methods Group a: "on strict", group b: "on loos" and group c: "off diet". A special questionnaire for self-esteem scores was created for these patients. Results Before psychological support, group a patients demonstrated 6/20 (30%) very high self-esteem, 9/20 (45%) high and 5/25 (25%) moderate. After support 14/20 (70%) were turned to very high, 5/20 (25%) represented high except one whose degrees remained an altered. group b 4/20 (20%) were very high, 7/20 (35%) were high, 3/20 (15%) moderate and the rest of them showed low self-esteem degrees, after support, 10/20 (50%) showed very high, 5/20 (25%) became high, 3/20 (15%) turned to moderate and 2/20 (10%) remained unaltered. Group c, 1/20 (5%) were very high self-esteemed, 7/20 (35%) were high, 6/20 (30%) were moderate and 6/20 (30%) with low self-esteemed, at the end of support, 6/20 (30%) become very high, 8/20 (40%) with high, 4/20 (20.0%), moderate self-esteem whereas the rest were unaltered. Conclusions Very high and high self-esteem degrees were demonstrated in patients who follow their PKU diet. Moderate and low self-esteem degrees were predominantly found in patients on loos and or off diet. Psychological supports commonly result in amelioration of self-esteem degrees.

Self-estimation of phenylketonuria patients on therapeutic diet. Psychological support.

Objectives Self-esteem is the degree to which the qualities and characteristics contained in one's self-concept are perceived to be positive. The aim of this study was to evaluate the self-esteem scores in phenylketonuria (PKU) patients on "strict", "loos" and "off diet". Sixty PKU patients were divided in three equal groups. Methods Group a: "on strict", group b: "on loos" and group c: "off diet". A special questionnaire for self-esteem scores was created for these patients. Results Before psychological support, group a patients demonstrated 6/20 (30%) very high self-esteem, 9/20 (45%) high and 5/25 (25%) moderate. After support 14/20 (70%) were turned to very high, 5/20 (25%) represented high except one whose degrees remained an altered. group b 4/20 (20%) were very high, 7/20 (35%) were high, 3/20 (15%) moderate and the rest of them showed low self-esteem degrees, after support, 10/20 (50%) showed very high, 5/20 (25%) became high, 3/20 (15%) turned to moderate and 2/20 (10%) remained unaltered. Group c, 1/20 (5%) were very high self-esteemed, 7/20 (35%) were high, 6/20 (30%) were moderate and 6/20 (30%) with low self-esteemed, at the end of support, 6/20 (30%) become very high, 8/20 (40%) with high, 4/20 (20.0%), moderate self-esteem whereas the rest were unaltered. Conclusions Very high and high self-esteem degrees were demonstrated in patients who follow their PKU diet. Moderate and low self-esteem degrees were predominantly found in patients on loos and or off diet. Psychological supports commonly result in amelioration of self-esteem degrees.

The beneficial effect of psychological support on mothers with PKU children who suffer from social discrimination and damage of quality of life.

Background Phenylketonuria (PKU) is a metabolic disorder of phenylalanine (phe) metabolism caused by the liver enzyme phe hydroxylase deficiency resulting in mental retardation. The only treatment for this disorder is the lifelong restriction of natural protein supplemented with phe-free amino acid formula. The aim of this study was to demonstrate the beneficial effect of psychological support in relation to the educational status on mothers with PKU children, who suffered from social discrimination (SD) and damage of quality of life (QLD). Methods A total number of 42 mothers with PKU children with a mean age of 26.8 years took part in this study. According to their educational status, they were divided into three groups: group a, primary school (n = 13); group b, high school (n = 15) and group c, university degree (n = 14). Psychological support was given once per week for 1 year. Results University degree mothers achieved the best results in ameliorating their symptoms and signs. Mothers who had completed high school felt a moderate amelioration of their SD and QL, whereas those who had finished primary school only felt a mild reduction of their symptoms. Educational status of the affected mothers should be always taken into account for the classification of the affected mothers into therapeutic groups. Familial and professional environment are very important for the success of psychological support. Conclusions Overall, the psychological support related to symptoms and signs of this metabolic disorder is in comparison with that in diabetic patients.

Replacement of breastfeeding with medical food for the treatment of galactosemia and phenylketonuria: maternal stress.

Breastfeeding replacement is the only treatment for galactosemia (GAL) and phenylketonuria (PKU) during infancy. We aimed to evaluate the stress degree in mothers who were obliged to replace breastfeeding with special formulas as the only treatment for the diseased newborns. Thirty-two mothers with GAL newborns, 19 on breastfeeding only and 13 on breastfeeding plus formula, participated in this study. Additionally, 54 mothers with PKU infants, 32 offered breastfeeding only and 22 breastfeeding plus formula, participated in the study. Stress degree was evaluated in both groups: GAL and PKU. Mothers on breastfeeding only experienced the highest degree of stress than those who were on breastfeeding plus formula. After 1 month of psychological support, most mothers were ameliorated: mothers on breastfeeding only felt better as compared to those on breastfeeding plus formula. Conversely, in mothers on breastfeeding plus formulas, symptoms and signs of stress almost disappeared. In conclusion, GAL or PKU mothers with breastfeeding only experienced the highest degree of stress when asked for breastfeeding replacement. Psychological support made all the studied groups to feel better or free of symptoms and signs of stress.

Optic nerve head damage relation to intracranial pressure and corneal properties of eye in glaucoma risk assessment.

This work presents results from numerical simulations of optic nerve head's (ONH) biomechanical behavior during exposure to elevated intraocular (IOP) and/or intracranial pressure (ICP) for ocular hypertension conditions. At the same time, a range of geometric and material properties of the eye structure and their interrelation with elevated IOP and ICP values are investigated. These simulations are performed on a generic model of the eye, which allows parametrical modification of geometric and material properties. Our main interest is in measuring ONH's potential damage in ocular hypertension due to intracranial pressure. Simulation results indicate a significant role of ICP in post-laminar neural tissue failure and a possible role of central corneal thickness (CCT) and scleral modulus in clinical assessment and treatment of patients with ocular hypertension (OHT). Specifically, CCT was found to affect ONH at early stages of damage in ocular hypertension conditions, and high scleral modulus seems to result in reduced shear failure in lamina cribrosa in a similar OHT state. These findings suggest that CCT could be a risk factor for glaucoma in OHT patients at initial stage along with cornea stiffness. Graphical abstract Graphical abstract.

Treatment of cervical myelopathy in patients with the fibromyalgia syndrome: outcomes and implications.

Some patients with fibromyalgia also exhibit the neurological signs of cervical myelopathy. We sought to determine if treatment of cervical myelopathy in patients with fibromyalgia improves the symptoms of fibromyalgia and the patients' quality of life. A non-randomized, prospective, case control study comparing the outcome of surgical (n = 40) versus non-surgical (n = 31) treatment of cervical myelopathy in patients with fibromyalgia was conducted. Outcomes were compared using SF-36, screening test for somatization, HADS, MMPI-2 scale 1 (Hypochondriasis), and self reported severity of symptoms 1 year after treatment. There was no significant difference in initial clinical presentation or demographic characteristics between the patients treated by surgical decompression and those treated by non-surgical means. There was a striking and statistically significant improvement in all symptoms attributed to the fibromyalgia syndrome in the surgical patients but not in the non-surgical patients at 1 year following the treatment of cervical myelopathy (P

Clinical evidence for cervical myelopathy due to Chiari malformation and spinal stenosis in a non-randomized group of patients with the diagnosis of fibromyalgia.

OBJECTIVE: While patients with fibromyalgia report symptoms consistent with cervical myelopathy, a detailed neurological evaluation is not routine. We sought to determine if patients with fibromyalgia manifest objective neurological signs of cervical myelopathy. METHODS: Two hundred and seventy patients, 18 years and older, who carried the diagnosis of fibromyalgia but who had no previously recognized neurological disease underwent detailed clinical neurological and neuroradiological evaluation for the prevalence of objective evidence of cervical myelopathy and radiological evidence of cerebellar tonsillar herniation (Chiari 1 malformation) or cervical spinal canal stenosis. RESULTS: Patients were primarily women (87%), of mean age 44 years, who had been symptomatic for 8 years (standard deviation, 6.3 years). The predominant complaints were neck/back pain (95%), fatigue (95%), exertional fatigue (96%), cognitive impairment (92%), instability of gait (85%), grip weakness (83%), paresthesiae (80%), dizziness (71%) and numbness (69%). Eighty-eight percent of patients reported worsening symptoms with neck extension. The neurological examination was consistent with cervical myelopathy: upper thoracic spinothalamic sensory level (83%), hyperreflexia (64%), inversion of the radial periosteal reflex (57%), positive Romberg sign (28%), ankle clonus (25%), positive Hoffman sign (26%), impaired tandem walk (23%), dysmetria (15%) and dysdiadochokinesia (13%). MRI and contrast-enhanced CT imaging of the cervical spine revealed stenosis. The mean antero-posterior (AP) spinal canal diameter at C2/3, C3/4, C4/5, C5/6, C6/7 and C7/T1 was 13.5 mm, 11.8 mm, 11.5 mm, 10.4 mm, 11.3 mm and 14.5 mm respectively, (CT images). In 46% of patients, the AP spinal diameter at C5/6 measured 10 mm, or less, with the neck positioned in mild extension, i.e., clinically significant spinal canal stenosis. MRI of the brain revealed tonsillar ectopia >5 mm in 20% of patients (mean=7.1+/-1.8 mm), i.e., Chiari 1 malformation. CONCLUSION. Our findings indicate that some patients who carry the diagnosis of fibromyalgia have both signs and symptoms consistent with cervical myelopathy, most likely resulting from spinal cord compression. We recommend detailed neurological evaluation of patients with fibromyalgia in order to exclude cervical myelopathy, a potentially treatable condition.