Binary vanadium pentoxide carbon-graphene foam composites derived from dark red hibiscus sabdariffa for advanced asymmetric supercapacitor.

The development of advanced electrode materials derived from biomass for the next generation of energy storage devices, such as supercapacitors with high specific energy and specific power coupled with a good cycle stability, is required to meet the high demand for electric vehicles and portable devices. In this study, sustainable binary vanadium pentoxide carbon-graphene foam composites (V2O5@C-R2HS/GF) were synthesized using a solvothermal method. The X-ray diffraction, Raman and FTIR techniques were used to study the structural properties of the composites (V2O5@C-R2HS/20 mg GF and V2O5@C-R2HS/40 mg GF). The SEM micrographs displayed an accordion-like morphology resulting from the graphene foam-modified V2O5@C-R2HS composite. The V2O5@C-R2HS, V2O5@C-R2HS/20 mg GF and V2O5@C-R2HS/40 mg GF composites were evaluated in a three-electrode configuration using 6 M potassium hydroxide (KOH) as an aqueous electrolyte. Furthermore, a two-electrode device was carried out by fabricating an asymmetric device (V2O5@C-R2HS/GF//AC) where V2O5@C-R2HS/20 mg GF was used as a positive electrode and activated carbon (AC) as a negative electrode at a cell voltage of 1.6 V in 6 M KOH. The V2O5@C-R2HS/GF//AC showed a high specific energy and specific power values of 55 W h kg-1 and 707 W kg-1, respectively, at a specific current of 1 A g-1. The asymmetric device presented a good stability test showing 99% capacity retention up to 10 000 cycles and was confirmed by the floating time up to 150 h with specific energy increasing 23.6% after the first 10 h. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)'.

One-Step Extraction of Olive Phenols from Aqueous Solution Using ß-Cyclodextrin in the Solid State, a Simple Eco-Friendly Method Providing Photochemical Stability to the Extracts.

The extraction of phenolic compounds from olive mill wastes is important, not only to avoid environmental damages, but also because of the intrinsic value of those biophenols, well-known for their high antioxidant potential and health benefits. This study focuses on tyrosol (Tyr) and hydroxytyrosol (HT), two of the main phenolic compounds found in olive mill wastes. A new, simple, and eco-friendly extraction process for the removal of phenolic compounds from aqueous solutions using native ß-cyclodextrin (ß-CD) in the solid state has been developed. Several ß-CD/biophenol molar ratios and biophenol concentrations were investigated, in order to maintain ß-CD mostly in the solid state while optimizing the extraction yield and the loading capacity of the sorbent. The extraction efficiencies of Tyr and HT were up to 61%, with a total solid recovery higher than 90% using an initial concentration of 100 mM biophenol and 10 molar equivalents of ß-CD. The photochemical stability of the complexes thus obtained was estimated from ∆E*ab curve vs. illumination time. The results obtained showed that the phenols encapsulated into solid ß-CD are protected against photodegradation. The powder obtained could be directly developed as a safe-grade food supplement. This simple eco-friendly process could be used for extracting valuable biophenols from olive mill wastewater.

Effect of porosity enhancing agents on the electrochemical performance of high-energy ultracapacitor electrodes derived from peanut shell waste.

In this study, the synthesis of porous activated carbon nanostructures from peanut (Arachis hypogea) shell waste (PSW) was described using different porosity enhancing agents (PEA) at various mass concentrations via a two-step process. The textural properties obtained were depicted with relatively high specific surface area values of 1457 m2 g-1, 1625 m2 g-1 and 2547 m2 g-1 for KHCO3, K2CO3 and KOH respectively at a mass concentration of 1 to 4 which were complemented by the presence of a blend of micropores, mesopores and macropores. The structural analyses confirmed the successful transformation of the carbon-containing waste into an amorphous and disordered carbonaceous material. The electrochemical performance of the material electrodes was tested in a 2.5 M KNO3 aqueous electrolyte depicted its ability to operate reversibly in both negative and positive potential ranges of 0.90 V. The activated carbon obtained from the carbonized CPSW:PEA with a mass ratio of 1:4 yielded the best electrode performance for all featured PEAs. The porous carbons obtained using KOH activation displayed a higher specific capacitance and the lower equivalent series resistance as compared to others. The remarkable performance further corroborated the findings linked to the textural and structural properties of the material. The assembled device operated in a neutral electrolyte (2.5 M KNO3) at a cell potential of 1.80 V, yielded a ca. 224.3 F g-1 specific capacitance at a specific current of 1 A g-1 with a corresponding specific energy of 25.2 Wh kg-1 and 0.9 kW kg-1 of specific power. This device energy was retained at 17.7 Wh kg-1 when the specific current was quadrupled signifying an excellent supercapacitive retention with a corresponding specific power of 3.6 kW kg-1. These results suggested that peanut shell waste derived activated carbons are promising candidates for high-performance supercapacitors.

Traumatic Brain Injury Related to Motor Vehicle Accidents in Guinea: Impact of Treatment Delay, Access to Healthcare, and Patient's Financial Capacity on Length of Hospital Stay and In-hospital Mortality.

BACKGROUND: Traumatic brain injury related to road traffic accidents poses a major challenge in resource-poor settings within Guinea. OBJECTIVE: To analyze the impact of treatment delay, access to healthcare, and patient's financial capacity on duration of hospital stay and in-hospital mortality. METHODOLOGY: Data from patients with traumatic brain injury secondary to motor vehicle accident admitted to a reference hospital (public or private) in Guinea during 2009 were analyzed. The association between various factors (treatment delay, access to healthcare, and patient's financial capacity) and prolonged hospital stay (>21 days) and in-hospital mortality were analyzed using two multivariate logistic regression models. RESULTS: The mean (±standard deviation) duration of hospital stay was 8.0 (±8.1) days. The risk of prolonged hospital stay increased by 60% when the time interval between accident and hospital arrival was greater than 12 hours compared with those in whom the time interval was less than 6 hours (adjusted odds ratio [OR] = 1.6, 95% confidence interval [CI] = 1.0-2.6, p = 0.03). Compared with patients with low-financial capacity, patients with medium-financial capacity (adjusted OR = 0.6, 95% CI = 0.4-0.8, p = 0.001) and those with high capacity (adjusted OR = 0.6, 95% CI = 0.4-0.9, p = 0.02) were less likely to have a prolonged hospital stay. The risk of in-hospital mortality was 2.6 times higher in patients with time interval between accident and hospital arrival greater than 12 hours compared with those in whom the time interval was less than 6 hours (adjusted OR = 2.6, 95% CI = 1.1-6.2 p = 0.03). In-hospital mortality was not related to patient's financial capacity. CONCLUSION: Prolonged hospital stay and higher in-hospital mortality was associated with longer time interval between accident and hospital arrival. This delay is attributed to inadequate condition of intercity roads and lack of emergency medical services.

Detection of Simian Immunodeficiency Virus in Semen, Urethra, and Male Reproductive Organs during Efficient Highly Active Antiretroviral Therapy.

UNLABELLED: A number of men receiving prolonged suppressive highly active antiretroviral therapy (HAART) still shed human immunodeficiency virus (HIV) in semen. To investigate whether this seminal shedding may be due to poor drug penetration and/or viral production by long-lived cells within male genital tissues, we analyzed semen and reproductive tissues from macaques chronically infected with simian immunodeficiency virus mac251 (SIVmac251) who were treated for 4 months with HAART, which was intensified over the last 7 weeks with an integrase inhibitor. We showed that a subset of treated animals continued shedding SIV in semen despite efficient HAART. This shedding was not associated with low antiretroviral drug concentrations in semen or in testis, epididymis, seminal vesicles, and prostate. HAART had no significant impact on SIV RNA in the urethra, whereas it drastically reduced SIV RNA levels in the prostate and vas deferens and to a lesser extent in the epididymis and seminal vesicle. The only detectable SIV RNA-positive cells within the male genital tract after HAART were urethral macrophages. SIV DNA levels in genital tissues were not decreased by HAART, suggesting the presence throughout the male genital tract of nonproductively infected cells. In conclusion, our results demonstrate that 4 months of HAART induced variable and limited control of viral infection in the male reproductive organs, particularly in the urethra, and suggest that infected long-lived cells in the male genital tract may be involved in persistent seminal shedding during HAART. These results pave the way for further investigations of male genital organ infection in long-term-treated infected individuals. IMPORTANCE: A substantial subset of men receiving prolonged HAART suppressing viral loads in the blood still harbor HIV in semen, and cases of sexual transmission have been reported. To understand the origin of this persistence, we analyzed the semen and male reproductive tissues from SIV-infected macaques treated with HAART. We demonstrated that persistent seminal shedding was not linked to poor drug penetration in semen or semen-producing prostate, seminal vesicle, epididymis, and testis. We revealed that HAART decreased SIV RNA to various extents in all male genital organs, with the exception of the urethra, in which SIV RNA(+) macrophages were observed despite HAART. Importantly, HAART did not impact SIV DNA levels in the male genital organs. These results suggest that infection of male genital organs, and particularly the urethra, could be involved in the release of virus in semen during HAART.

Assessing neuromuscular mechanisms in human-exoskeleton interaction.

In this study, we propose to evaluate a 7 DOF exoskeleton in terms of motion control. Using criteria from the human motor control literature, inverse optimization was performed to assess an industrial screwing movement. The results of our study show that the hybrid composition of the free arm movement was accurately determined. At contrary, when wearing the exoskeleton, which produces an arbitrary determined torque compensation, the motion is different from the naturally adopted one. This study is part of the evaluation and comprehension of the complex neuromuscular mechanism resulting in wearing an exoskeleton several hours per day for industrial tasks assistance.

Toward an affordable and user-friendly visual motion capture system.

The present study aims at designing and evaluating a low-cost, simple and portable system for arm joint angle estimation during grasping-like motions. The system is based on a single RGB-D camera and three customized markers. The automatically detected and tracked marker positions were used as inputs to an offline inverse kinematic process based on bio-mechanical constraints to reduce noise effect and handle marker occlusion. The method was validated on 4 subjects with different motions. The joint angles were estimated both with the proposed low-cost system and, a stereophotogrammetric system. Comparative analysis shows good accuracy with high correlation coefficient (r= 0.92) and low average RMS error (3.8 deg).