“Greener” chemical modification of cellulose nanocrystals via oxa-Michael addition with N-Benzylmaleimide

Surface modification of cellulose nanocrystals (CNCs) was conducted by an oxa-Michael addition of primary hydroxyl groups on the CNC surface with N-Benzylmaleimide (BnM). Six principles of green chemistry were used to obtain the hydrophobized CNC. Two catalytic approaches were used, a self-catalyzed reaction where alkyl sulfuric acid on the surface of the CNC was the catalyst, and a base-catalyzed approach using triethylamine (TEA). DMSO was chosen as reaction solvent due to its low cost, low toxicity and ability to disperse native CNC compared to other polar diprotic solvents. NMR and FTIR studies confirmed the successful modification of CNCs in both reaction routes. The TEA-catalyzed reaction showed a higher BnM conversion at 70 ​°C after 72 ​h (46 ​± ​2%) compared to the self-catalyzed reaction at 100 ​°C (24 ​± ​2%). Since BnM was added at a two-fold excess compared to superficial primary –OH groups, these had estimated conversions of 92% and 48%, for the base catalyzed and acid catalyzed routes, respectively. Zeta potential measurements suggest, the sulfate groups were retained after the modification reaction. AFM demonstrated no change in particle morphology after modification. Modified CNCs degraded at a higher temperature (390 ​± ​8 ​°C) when the reaction was catalyzed by TEA compared to native CNCs and the self-catalyzed product (220 ​± ​10 ​°C). Contact angle measurements demonstrated the increased hydrophobicity of the modified nanoparticles. Visual inspection and UV–vis spectroscopy demonstrated the modified CNCs had an increased affinity towards organic solvents like acetone, acetonitrile and toluene

A 30-day follow-up study on the prevalence of SARS-COV-2 genetic markers in wastewater from the residence of COVID-19 patient and comparison with clinical positivity

Wastewater based epidemiology (WBE) is an important tool to fight against COVID-19 as it provides insights into the health status of the targeted population from a small single house to a large municipality in a cost-effective, rapid, and non-invasive way. The implementation of wastewater based surveillance (WBS) could reduce the burden on the public health system, management of pandemics, help to make informed decisions, and protect public health. In this study, a house with COVID-19 patients was targeted for monitoring the prevalence of SARS-CoV-2 genetic markers in wastewa-ter samples (WS) with clinical specimens (CS) for a period of 30 days. RT-qPCR technique was employed to target non-structural (ORF1ab) and structural-nucleocapsid (N) protein genes of SARS-CoV-2, according to a validated experimental protocol. Physiological, environmental, and biological parameters were also measured following the American Public Health Association (APHA) standard protocols. SARS-CoV-2 viral shedding in wastewater peaked when the highest number of COVID-19 cases were clinically diagnosed. Throughout the study period, 7450 to 23,000 gene copies/1000 mL were detected, where we identified 47 % (57/120) positive samples from WS and 35 % (128/360) from CS. When the COVID-19 patient number was the lowest (2), the highest CT value (39.4; i.e., lowest copy number) was identified from WS. On the other hand, when the COVID-19 patients were the highest (6), the lowest CT value (25.2 i.e., highest copy numbers) was obtained from WS. An advance signal of increased SARS-CoV-2 viral load from the COVID-19 patient was found in WS earlier than in the CS. Using customized primer sets in a traditional PCR approach, we confirmed that all SARS-CoV-2 variants identified in both CS and WS were Delta variants (B.1.617.2). To our knowledge, this is the first follow-up study to determine a temporal relationship be-tween COVID-19 patients and their discharge of SARS-CoV-2 RNA genetic markers in wastewater from a single house including all family members for clinical sampling from a developing country (Bangladesh), where a proper sewage system is lacking. The salient findings of the study indicate that monitoring the genetic markers of the SARS-CoV-2 virus in wastewater could identify COVID-19 cases, which reduces the burden on the public health system during COVID-19 pandemics.Peer reviewe

Experimental Implementation of Optical-CDMA for Medical Extra-WBAN Links

International audienceWe consider the use of optical wireless technology based on infrared signals for multiuser wireless body-area networks (WBANs) in medical applications. For the case of uplink extra-WBAN signal transmission, we propose a simple optical code-division multiple access (O-CDMA) signaling scheme to manage the multiple-access channel. We experimentally evaluate the link performance in terms of bit-and frame-error-rates by implementing the proposed scheme on the programmable logic, and show the efficiency of this approach in dealing with multiuser interference, as well as its low-complexity. Index Terms-Body area networks, infrared link, implementation of WBAN, optical wireless communications, optical code-division multiple access, WBAN prototypes

High-Rate Full-Duplex Optical Wireless Data Transmission for Medical Applications

Health monitoring of aged people from a remote distance and continuous monitoring of patients in medical centers or hospitals is very crucial to avoid receiving wrong medical treatments. This can be accomplished by sending timely data from several medical devices via a wireless body-area network (WBAN). WBANs based on radiofrequency technology are susceptible to electromagnetic interference and potentially suffer from security concerns. Optical wireless communications (OWC) have evolved as a more appropriate technology for wireless data transfer within WBANs. The main objective of this thesis is to design and develop a high-rate full-duplex transmission link for medical WBANs. We investigate OWC transmission between an access point (AP) and a number of users for downlink and uplink data communication. Particular attention is devoted to the suitable modulation and multiple access techniques insuring reliable data transmission in different use cases

Impact behavior of energy absorbing helmet liners with PA12 lattice structures: A computational study

Existing helmets have a significant but limited ability to reduce the severity of brain injury and the fatality rate during motorcycle accidents. Helmet designs with a special focus on reducing head injuries caused by rotational effects have attracted great interest in recent times. This paper uses a computational approach to study the generation of new helmet designs with lattice liners made of polyamide12 (PA12) material. Three design pos sibilities and three distinct unit cell topologies were used to create the liners as the energy absorbing and dissipating part of the helmet. PA12 lattice samples were additively manufactured and tested under quasi-static and dynamic compression loads. The test data, showing ductile to brittle transition due to strain-rate effects, were used to validate the finite element models of the lattices. Simulations of the linear high energy and oblique impacts on the coupled headform and liner were carried out following the state-of-the-art helmet standard ECE R22.06. The findings of this study suggest that PA12 lattice liners have an excellent capability of reducing peak rotational acceleration. Many liners can outperform the protection levels offered by existing expandable poly styrene foam liners for single impacts, but at the expense of weight. The performance of the liners can be improved by choosing the topology in such a way that the stress can be distributed through the struts. Moreover, a lattice liner having a balanced energy absorption capability and stiffness would perform better than other lattice liners

The road towards protection of all against tetanus.

In low- and middle-income countries (LMICs), tetanus continues to be a major public health concern. Although vaccination campaigns have been effective in lowering the incidence of tetanus worldwide, some areas continue to experience a considerable number of cases and fatalities. Adult tetanus is frequently underreported because there is insufficient systematic surveillance and reporting. A high proportion of tetanus patients die because of a lack of adequate critical care services, particularly ventilator support, with limited access to existing facilities due to high costs. Hence, the case fatality rate of adult tetanus remains high. Women and children are protected because of regular and booster immunization strategies implemented around the world. However, men are disproportionately affected by tetanus. Booster dosage based on the World Health Organization (WHO)-recommended schedule should be given to eligible children and adolescent boys. In addition, tetanus vaccination needs to be promoted among adults in vulnerable jobs. Functional strategies could help pave the way toward the protection of all against tetanus

Effect of the Interactions between Oppositely Charged Cellulose Nanocrystals (CNCs) and Chitin Nanocrystals (ChNCs) on the Enhanced Stability of Soybean Oil-in-Water Emulsions

Chitin nanocrystals (ChNCs) and cellulose nanocrystals (CNCs) have been recently used to stabilize emulsions; however, they generally require significant amounts of salt, limiting their applicability in food products. In this study, we developed nanoconjugates by mixing positively charged ChNCs and negatively charged CNCs at various ChNC:CNC mass ratios (2:1, 1:1, and 1:2), and utilized them in stabilizing soybean oil–water Pickering emulsions with minimal use of NaCl salt (20 mM) and nanoparticle (NP) concentrations below 1 wt%. The nanoconjugates stabilized the emulsions better than individual CNC or ChNC in terms of a reduced drop growth and less creaming. Oppositely charged CNC and ChNC neutralized each other when their mass ratio was 1:1, leading to significant flocculation in the absence of salt at pH 6. Raman spectroscopy provided evidence for electrostatic interactions between the ChNCs and CNCs, and generated maps suggesting an assembly of ChNC bundles of micron-scale lengths intercalated by similar-size areas predominantly composed of CNC. The previous measurements, in combination with contact angles on nanoparticle films, suggested that the conjugates preferentially exposed the hydrophobic crystalline planes of CNCs and ChNCs at a 1:1 mass ratio, which was also the best ratio at stabilizing soybean oil–water Pickering emulsions

Exploring the molecular level interaction of Xenoestrogen phthalate plasticisers with oestrogen receptor alpha (ERα) Y537S mutant

Phthalates are Endocrine Disrupting plasticisers (EDCs) which can compete with natural oestrogens and modify ER’s biological responses. Gene expression experiments show oestrogenic and anti-oestrogenic effects of phthalates on ERα. Phthalates have been examined for anti-oestrogenic activities against a somatic mutation of ERα, Y537S, a key mutation in ER-positive breast cancer cells. Here, we examined the binding affinity, dynamic characteristics, and quantitative structure–activity connection of certain phthalates against a constitutively active somatic mutant ERα (Y537S). We compared their molecular dynamic and energetic properties with 4-Hydroxytamoxifen (4OHT) and Thioridazine. Using Molecular Dynamics Simulation and protein structure analyses, we found that ligand binding altered the hydrophobic core and phthalates affected the secondary structure of Y537S ERα but did not affect H11, H11–H12 loop, H12, or antiestrogen-resistant areas. The phthalate stabilised the mutant ERα agonist structure. Compared to the Apo conformation, the Phthalate-bound H11–H12 loop and H12 displayed less fluctuation and movement. This research shows that phthalates can impair ER+ positive breast cancer cells by maintaining the agonist conformation rather than demonstrating anti-oestrogenic actions. Principal component analysis (PCA) and partial-least-square (PLS) regression were used to further understand phthalate ligands’ binding to ER LBD. PLS model accurately predicted phthalates ligands’ binding energy (\u3e94%)

Impact of Synchronization Errors on the Performance of ACO-OFDMA Signaling for Medical Extra-WBAN Links

International audienceThis paper considers the use of infrared-based optical wireless communications for multiuser uplink wireless body-area networks. We propose the use of optical-orthogonal frequency division multiple access (O-OFDMA) signaling to manage the multiple access (MA) requirement for relatively high-rate medical applications. In particular, we consider asymmetrically clipped O-OFDMA and analyze its performance in terms of bit-errorrate and outage probability in the presence of multiuser time synchronization errors. These latter may occur due to mobility and random transmitter orientations, and will impact the link performance by inducing MA interference (MAI). We show that the effect of MAI increases with increasing the data rate. For instance, for 1 and 2 Mbps data rates, to achieve a target biterror-rate of 10 −3 , the link distance is limited to 1.9 and 1 m, respectively, compared to 2.2 and 1.8 m in the absence of MAI. Index Terms-Wireless body area networks, optical-orthogonal frequency-division multiple access, synchronization errors, optical wireless communications