Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications.

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π-π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxide.

Axonal motor protein KIF5A and associated cargo deficits in multiple sclerosis lesional and normal-appearing white matter.

AIMS: Understanding the causes of axonal pathology remains a key goal in the pursuit of new therapies to target disease progression in multiple sclerosis (MS). Anterograde axonal transport of many proteins vital for axonal viability is mediated by the motor protein KIF5A, which has been linked to several neurological diseases. This study aimed to investigate the expression of KIF5A protein and its associated cargoes: amyloid precursor protein (APP) and neurofilament (NF) in post mortem MS and control white matter (WM) and to determine if KIF5A expression is influenced by the presence of MS risk single nucleotide polymorphisms (SNPs) identified in the region of the KIF5A gene. METHODS: Using immunoblotting assays we analysed the expression of KIF5A, APP and NF phospho-isoforms in 23 MS cases and 12 controls. RESULTS: We found a significant reduction in KIF5A and associated cargoes in MS WM and an inverse correlation between KIF5A and APP/NF protein levels. Furthermore, homozygous carriers of MS risk gene SNPs show significantly lower levels of KIF5A protein compared to MS patients with no copies of the risk SNPs. CONCLUSIONS: We conclude that reduced expression of axonal motor KIF5A may have important implications in determining axonal transport deficits and ongoing neurodegeneration in MS.

Observation of Single-Photon Superradiance and the Cooperative Lamb Shift in an Extended Sample of Cold Atoms.

We report direct, time-resolved observations of single-photon superradiance in a highly extended, elliptical sample of cold ^{87}Rb atoms. The observed rapid decay rate is accompanied by its counterpart, the cooperative Lamb shift. The rate of the strongly directional decay, and the associated shift, scale linearly with the number of atoms, demonstrating the collective nature of the observed quantities.

Activated carbon derived from waste coffee grounds for stable methane storage.

An activated carbon material derived from waste coffee grounds is shown to be an effective and stable medium for methane storage. The sample activated at 900 °C displays a surface area of 1040.3 m(2) g(-1) and a micropore volume of 0.574 cm(3) g(-1) and exhibits a stable CH4 adsorption capacity of ∼4.2 mmol g(-1) at 3.0 MPa and a temperature range of 298 ± 10 K. The same material exhibits an impressive hydrogen storage capacity of 1.75 wt% as well at 77 K and 100 kPa. Here, we also propose a mechanism for the formation of activated carbon from spent coffee grounds. At low temperatures, the material has two distinct types with low and high surface areas; however, activation at elevated temperatures drives off the low surface area carbon, leaving behind the porous high surface area activated carbon.

Reduced axonal motor protein expression in non-lesional grey matter in multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a neurological disease characterised by central nervous system inflammation, demyelination, axonal degeneration and neuronal injury. Preventing neuronal and axon damage is of paramount importance in attempts to prevent disease progression. Intact axonal transport mechanisms are crucial to axonal integrity and evidence suggests these mechanisms are disrupted in MS. Anterograde axonal transport is mediated to a large extent through the kinesin superfamily proteins. Recently, certain kinesin superfamily proteins (KIF5A, KIF1B and KIF21B) were implicated in MS pathology. OBJECTIVES: To investigate the expression of KIF5A, KIF21B and KIF1B in MS and control post-mortem grey matter. METHODS: Using both quantitative real-time polymerase chain reaction (PCR) and Immunodot-blots assays, we analysed the expression of kinesin superfamily proteins in 27 MS cases and 13 control cases not linked to neurological disease. RESULTS: We have shown significant reductions in KIF5A, KIF21B and KIF1B messenger ribonucleic acid (mRNA) expression and also KIF5A protein expression in MS grey matter, as compared to control grey matter. CONCLUSION: We have shown significant reductions in mRNA and protein levels of axonal motor proteins in the grey matter of MS cases, which may have important implications for the pathogenesis of neuronal/axonal injury in the disease.

Reversible CO2 adsorption by an activated nitrogen doped graphene/polyaniline material.

For effective adsorption of carbon dioxide (CO2), we investigate a porous N functionalized graphene adsorbent produced by the chemical activation of a reduced graphene oxide/polyaniline composite. The N-doped graphene composite is microporous with a maximum BET surface area of 1336 m(2) g(-1). It shows a highly reversible maximum CO2 storage capacity of 2.7 mmol g(-1) at 298 K and 1 atm (5.8 mmol g(-1) at 273 K and 1 atm). The N-doped graphene shows good stability during recycling with only an initial decrease of 10% (3-2.7 mmol g(-1)) in adsorption capacity before attaining a cycling equilibrium. The adsorbance capacity is correlated with N content × pore volume or N content × surface area. Given that there is no proper correlation parameter, these factors can be used to increase the CO2 adsorption capacity of N-doped graphene materials for practical utility. The as synthesized material also displays selectivity towards CO2 adsorption compared to H2, N2, Ar or CH4. The as formed material shows that graphene can be uniformly N-doped using the presented synthetic method.

Synthesis of N-doped microporous carbon via chemical activation of polyindole-modified graphene oxide sheets for selective carbon dioxide adsorption.

A polyindole-reduced graphene oxide (PIG) hybrid was synthesized by reducing graphene oxide sheets in the presence of polyindole. We have shown PIG as a material for capturing carbon dioxide (CO2). The PIG hybrid was chemically activated at temperatures of 400-800 °C, which resulted in nitrogen (N)-doped graphene sheets. The N-doped graphene sheets are microporous with an adsorption pore size of 0.6 nm for CO2 and show a maximum (Brunauer, Emmet and Teller) surface area of 936 m(2) g(-1). The hybrid activated at 600 °C (PIG6) possesses a surface area of 534 m(2) g(-1) and a micropore volume of 0.29 cm(3) g(-1). PIG6 shows a maximum CO2 adsorption capacity of 3.0 mmol g(-1) at 25 °C and 1 atm. This high CO2 uptake is due to the highly microporous character of the material and its N content. The material retains its original adsorption capacity on recycling even after 10 cycles (within experimental error). PIG6 also shows high adsorption selectivity ratios for CO2 over N2, CH4 and H2 of 23, 4 and 85 at 25 °C, respectively.

Highly selective and stable carbon dioxide uptake in polyindole-derived microporous carbon materials.

Adsorption with solid sorbents is considered to be one of the most promising methods for the capture of carbon dioxide (CO2) from power plant flue gases. In this study, microporous carbon materials used for CO2 capture were synthesized by the chemical activation of polyindole nanofibers (PIF) at temperatures from 500 to 800 °C using KOH, which resulted in nitrogen (N)-doped carbon materials. The N-doped carbon materials were found to be microporous with an optimal adsorption pore size for CO2 of 0.6 nm and a maximum (Brunauer-Emmett-Teller) BET surface area of 1185 m(2) g(-1). The PIF activated at 600 °C (PIF6) has a surface area of 527 m(2) g(-1) and a maximum CO2 storage capacity of 3.2 mmol g(-1) at 25 °C and 1 bar. This high CO2 uptake is attributed to its highly microporous character and optimum N content. Additionally, PIF6 material displays a high CO2 uptake at low pressure (1.81 mmol g(-1) at 0.2 bar and 25 °C), which is the best low pressure CO2 uptake reported for carbon-based materials. The adsorption capacity of this material remained remarkably stable even after 10 cycles. The isosteric heat of adsorption was calculated to be in the range of 42.7-24.1 kJ mol(-1). Besides the excellent CO2 uptake and stability, PIF6 also exhibits high selectivity values for CO2 over N2, CH4, and H2 of 58.9, 12.3, and 101.1 at 25 °C, respectively, and these values are significantly higher than reported values.

Synthesis of nano zerovalent iron nanoparticles--graphene composite for the treatment of lead contaminated water.

A Nano zerovalent iron nanoparticles graphene composite (G-nZVI) was prepared via a sodium borohydride reduction of graphene oxide and iron chloride under an argon atmosphere. Powder X-ray diffraction patterns showed the formation of the magnetic graphene/nanoscale-zerovalent-iron (G-nZVI) composites and bare nanoscale-zerovalent-iron (nZVI) particles. TEM analysis shows the formation of ~10 nm particles. Adsorption experiments show a maximum Pb(II) adsorption capacity for the G-nZVI composite with 6 wt% graphene oxide loading. Additionally the effects of pH, temperature, contact time, ionic strength and initial metal ion concentration on Pb(II) ion removal were studied. X-ray photoelectron spectroscopy analysis after adsorption results confirmed the composite's ability to adsorb and immobilize lead more efficiently in its zerovalent and bivalent forms, as compared to bare iron nanoparticles. The adsorption of Pb(II) ions fit a pseudo-second-order kinetic model, and adsorption isotherms can be described using the Freundlich equations. G-nZVI shows great potential as an efficient adsorbent for lead immobilization from water, as it exhibits stability, reducing power, a large surface area, and magnetic separation.

Evaluation of field-testing protocols to diagnose insulin dysregulation in ponies using a Bayesian approach.

Field tests and their association with laminitis have not been evaluated in large cohorts. The objectives of this study were to evaluate the performance of basal insulin (BI), the oral sugar test (OST) and the insulin tolerance test (ITT) to diagnose ID and investigate their association with laminitis. Insulin dysregulation status was determined in 146 ponies using BI (insulin concentration >20 µIU/mL), an OST (insulin concentration >65 µIU/mL at 60 or 90 min after oral administration of 0.45 mL/kg corn syrup) and an ITT (< 50% reduction in glucose concentration 30 min after intravenous administration of 0.1 IU/kg insulin). Laminitis was identified using modified-Obel scores. A Bayesian approach was used to define the characteristics of the tests and receiver operating characteristic curves were used to assess their association with laminitis. All tests were well tolerated and laminitis was diagnosed in 9% of ponies. Insulin dysregulation was diagnosed in 15% of ponies using BI, 38% using the OST and 54% using the ITT with 11% of ponies positive for all three tests. The sensitivities and specificities of BI, the OST and the ITT to diagnose ID were 0.52 (95% confidence interval [CI], 0.35-0.79) and 0.97 (95% CI, 0.91 - 1.00), 0.84 (95% CI, 0.70 - 0.94) and 0.60 (95% CI, 0.49 - 0.71), and 0.85 (95% CI, 0.68-0.96) and 0.88 (95% CI, 0.75 - 0.97), respectively. Only BI and the OST were associated with laminitis (P = 0.003 and 0.015, respectively).

Mitochondrial sirtuins--a new therapeutic target for repair and protection in multiple sclerosis.

Given the significant socioeconomic impact of progressive multiple sclerosis (MS) and the paucity of treatment options, there is an urgent need to develop new and effective therapies for this disabling condition. The relatively recent appreciation that progressive disability is largely driven by neuronal loss has focused considerable research attention on neuroprotective strategies. This has coincided with the emergence of oxidative damage as a prominent effector mechanism of axonal damage in studies of MS pathogenesis, which has opened up a new range of putative targets for neuroprotective therapy in MS. Mitochondrial sirtuins are NAD(+)-dependent protein deacetylases associated with the control of metabolism, aging, and stem cell proliferation and differentiation. Their role in inflammatory demyelinating disease has not been fully characterized, and is the subject of ongoing research. Here, we expound the rationale behind selecting mitochondrial sirtuins as a therapeutic target in demyelinating disease, and report preliminary data that warrant further investigation.

Graphene-SnO2 composites for highly efficient photocatalytic degradation of methylene blue under sunlight.

Graphene sheets decorated with SnO(2) nanoparticles (RGO-SnO(2)) were prepared via a redox reaction between graphene oxide (GO) and SnCl(2). Graphene oxide (GO) was reduced to graphene (RGO) and Sn(2+) was oxidized to SnO(2) during the redox reaction, leading to a homogeneous distribution of SnO(2) nanoparticles on RGO sheets. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show uniform distribution of the nanoparticles on the RGO surface and high-resolution transmission electron microscopy (HRTEM) shows an average particle size of 3-5 nm. The RGO-SnO(2) composite showed an enhanced photocatalytic degradation activity for the organic dye methylene blue under sunlight compared to bare SnO(2) nanoparticles. This result leads us to believe that the RGO-SnO(2) composite could be used in catalytic photodegradation of other organic dyes.

Fusion between human mesenchymal stem cells and rodent cerebellar Purkinje cells.

AIMS: we explored whether cellular fusion and heterokaryon formation between human and rodent cells in the cerebellum of mice occurs after intravenous injection of human bone marrow-derived mesenchymal stem cells (MSCs). The influence of central nervous system inflammation on this process was also assessed. In addition, we examined whether tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, factors associated with inflammation, increase cellular fusion between human MSCs and rodent cerebellar neurons in vitro. METHODS AND RESULTS: human MSCs were intravenously injected into mice with experimental autoimmune encephalomyelitis (EAE) and control mice. After 22 days, mouse Purkinje cells expressing human Golgi Zone were found within the Purkinje cell layer of the cerebellum, indicating that fusion and heterokaryon formation had occurred. The numbers of heterokaryons in the cerebellum were markedly increased in mice with EAE compared with control mice. Rodent cerebellar neuronal cells labelled with enhanced green fluorescent proteinin vitro were co-cultured with human bone marrow-derived MSCs in the presence of TNF-alpha and/or IFN-gamma to determine their influence on fusion events. We found that fusion between MSCs and cerebellar neurons did occur in vitro and that the frequency of cellular fusion increased in the presence of TNF-alpha and/or IFN-gamma. CONCLUSIONS: we believe that this is the first paper to define fusion and heterokaryon formation between human MSCs and rodent cerebellar neurons in vivo. We have also demonstrated that fusion between these cell populations occurs in vitro. These findings indicate that MSCs may be potential therapeutic agents for cerebellar diseases, and other neuroinflammatory and neurodegenerative disorders.

Hidradenitis suppurativa: a disease of the absent sebaceous gland? Sebaceous gland number and volume are significantly reduced in uninvolved hair follicles from patients with hidradenitis suppurativa.

BACKGROUND: The pathogenesis of hidradenitis suppurativa (HS) is not clearly understood. The nomenclature suggests an important role for the apocrine glands but recent evidence implicates the pilosebaceous unit as a more likely candidate to play a central role in the pathogenesis. OBJECTIVES: Our aim was to estimate the volume of the follicular epithelium, the follicular lumen and the sebaceous glands of patients with HS and healthy controls by means of stereology. METHODS: Four-millimetre punch biopsies were taken from 21 patients with HS and nine healthy controls, fixed in formalin, embedded in paraffin and stained with haematoxylin and eosin prior to volume estimation using the Cavalieri principle. RESULTS: Sebaceous gland tissue could be visualized in only 10 of 15 suitable hair follicle biopsies from patients with HS but was present in all biopsies from healthy controls (P = 0·05) and the mean sebaceous gland volume per follicle was one-seventh of that of healthy controls (P = 0·03). There was no significant difference between patients with HS and healthy controls with regard to follicular epithelium and follicle lumen volume. CONCLUSIONS: Our results suggest that the absence or reduced volume of the sebaceous gland may play a role in the pathogenesis of HS. The presence of fibrosis suggests that sebaceous glands are obliterated early in the pathogenesis of HS.

Stereological estimation of epidermal volumes and dermo-epidermal surface area in normal skin.

Quantitative morphological studies of the healthy epidermis are essential in providing a range of parameter estimates that can be considered within the range of normality. Stereology is a set of statistical tools that provides potentially unbiased and precise estimates of 3-dimensional tissue characteristics from 2-dimensional sections. We set out to establish reference values for the volume of the viable epidermis contained within a four-millimetre punch biopsy (V(epi)), the volume of the stratum corneum (V(SC)) and the surface area of the dermo-epidermal junction(A(DEJ)) in 4 predetermined body regions by use of stereology. Four-millimetre punch biopsies were taken from 20 freshly diseased corpses, fixed in formalin and embedded in paraffin. V(epi), V(SC) and A(DEJ) were established stereologically for all 4 body locations followed by pairwise comparison of means after Bonferroni correction. V(epi) was significantly larger in the sole compared to all other body locations (p < 0.01). Furthermore, linear regression analysis showed a strong linear relationship between V(epi) and V(SC) in the sole (r = 0.70). Our results suggest that the viable layers of the epidermis might also serve a mechanical function, either directly or by providing the stratum corneum with keratinocytes to support the hyperkeratosis in the weight-bearing parts of the skin.

Systematic review of rotator cuff tears in workers' compensation patients.

BACKGROUND: The burden imposed by workplace rotator cuff (RC) injuries has been reasonably defined. However, literature associated with the demographic characteristics and 'best practices' to manage such injuries among workers' compensation (WC) patients is scant. AIMS: To consolidate the existing literature on full-thickness RC tears among WC patients. Subject, shoulder and injury characteristics were examined to determine if and how WC recipients may differ from their non-compensable counterparts. METHODS: A systematic search (databases, clinical practice guideline web resources, conference proceedings and reference lists) revealed 450 abstracts. Two blinded reviewers independently assessed abstracts for inclusion. Sixty abstracts were subsequently included in a blinded full manuscript review. Seventeen of these manuscripts (3.8% of sample; 11 intervention and 6 determinant) were included in the present review. RESULTS: Previous studies demonstrate that operative interventions are appropriate for full-thickness RC tears as substantial gains in range of motion, strength and quality of life were witnessed within the first post-operative year. Non-operative interventions, including workplace-based work hardening, physical therapy and the use of an early referral system, were shown to improve outcomes. Conflicting results exist with respect to determinants such as age and sex. Importantly, WC patients had consistently poorer outcomes than non-WC patients. CONCLUSIONS: Our results show that although WC patients experience substantial benefits from various treatments for full-thickness RC tears, disparities exist between them and their non-WC counterparts. The lack of WC-specific literature limited our results. Larger studies, particularly ones comparing WC patients with their non-compensable counterparts, are crucial to allow for future evidence-based recommendations.

The surgical history of the amputated limb according to the indication for revascularization: diabetic foot, acute ischaemia, aneurysmal disease, chronic arterial occlusive disease.

BACKGROUND: To investigate whether the indication for the first revascularization (diabetic foot, acute ischaemia, aneurysmal disease, chronic occlusive disease) determines the surgical history and survival time in amputated limbs. METHODS: The surgical history of lower extremities amputated between 2002 and 2009 was reviewed for the number of (endo)vascular procedures, minor amputations, wound debridements, complications requiring surgery (acute ischaemia, bleeding, graft infection) and limb survival time (LST). RESULTS: 100 limbs were included in the study. The four groups underwent a similar number of surgical procedures (mean 4.1). Diabetic foot limbs had fewer revascularizations (mean 1.3, p = 0.003) and complications (mean 0.1, p = 0.005), but more minor amputations and wound debridements (mean 1.3, p = 0.002), in a significantly shorter LST (mean 555 days, p = 0.003). Acute ischaemic limbs showed the shortest LST (mean 179 days, p = 0.003) and significantly more complications (mean 0.8, p = 0.005). Limbs initially treated for aneurysmal disease or chronic occlusive disease had the highest number of revascularizations (mean resp. 2.7 and 2.6) and the longest LST (mean resp. 1669 and 1459 days, p = 0.001). Limbs with advanced chronic occlusive disease (rest pain or gangrene) presented with fewer revascularisations (mean resp. 2.5 and 1.8, p = 0.01) and a shorter LST (mean resp. 1284 and 794 days, p = 0.004) compared to claudicants. CONCLUSIONS: Our study suggests that the surgical history and limb survival in amputated limbs is disease and stage specific, and determined by the indication of the first revascularisation.

KIF5A and the contribution of susceptibility genotypes as a predictive biomarker for multiple sclerosis.

There is increasing interest in the development of multiple sclerosis (MS) biomarkers that reflect central nervous system tissue injury to determine prognosis. We aimed to assess the prognostic value of kinesin superfamily motor protein KIF5A in MS by measuring levels of KIF5A in cerebrospinal fluid (CSF) combined with analysis of single nucleotide polymorphisms (SNPs; rs12368653 and rs703842) located within a MS susceptibility gene locus at chromosome 12q13-14 region. Enzyme-linked immunosorbent assay was used to measure KIF5A in CSF obtained from two independent biobanks comprising non-inflammatory neurological disease controls (NINDC), clinically isolated syndrome (CIS) and MS cases. CSF KIF5A expression was significantly elevated in progressive MS cases compared with NINDCs, CIS and relapsing-remitting MS (RRMS). In addition, levels of KIF5A positively correlated with change in MS disease severity scores (EDSS, MSSS and ARMSSS), in RRMS patients who had documented disease progression at 2-year clinical follow-up. Copies of adenine risk alleles (AG/AA; rs12368653 and rs703842) corresponded with a higher proportion of individuals in relapse at the time of lumbar puncture (LP), higher use of disease-modifying therapies post LP and shorter MS duration. Our study suggests that CSF KIF5A has potential as a predictive biomarker in MS and further studies into the potential prognostic value of analysing MS susceptibility SNPs should be considered.

Gender differences in cardiovascular risk factors in a carotid endarterectomy population.

AIM: Present knowledge about the epidemiology and the distribution of the cardiovascular risk factors of carotid artery atherosclerosis is limited. The aim of the study was to detect possible gender differences in cardiovascular risk factors in carotid endarterectomy patients. METHODS: Between 1998 and 2003 the cardiovascular risk factors of 804 consecutive isolated carotid endarterectomies were prospectively recorded. The data of 567 men and 237 women were compared and subgroup analysis of young and old male and female subjects was performed. RESULTS: The number of cardiovascular risk factors per patient is higher in men, hypertension is more predominant in women, tobacco use is twice as often present in men. The most frequent risk factors are, in men, tobacco use and hypertension, and, in women, hypertension and hyperlipidemia. The most frequent combination in the male group is tobacco/hypertension/hyperlipidemia and in the female group hypertension/hyperlipidemia. The gender differences were more striking in patients younger than 75 years, after this age the number of cardiovascular risk factor per patient declined in both sexes, the number of smokers decreased but remains higher in men, diabetes is more frequent in women and hypertension and hyperlipidemia become the important risk factors in men as well in women. CONCLUSIONS: There are gender differences in the distribution and in the combinations of cardiovascular risk factors in our selected patients. These findings suggest that screening for carotid artery atherosclerosis should particularly be aimed at people with the combinations of risk factors described above.