Search Results (30)

Nanosized manganese dioxide (MnO₂) material has been successfully incorporated into a graphene oxide (GO) sensitive layer. Since this type of heterojunction has never been reported in the literature related to gas sensing, these sensors were prepared, tested, and reported. The morphological properties and composition of the MnO₂@GO material have been thoroughly studied via FESEM, XRD, Raman spectroscopy, HR-TEM, and ATR-IR. Gas sensitivity and selectivity towards mainly NO₂ and other gases (NH₃, CO, ethanol, benzene, and H₂) have also been studied. The obtained sensors were exposed to different concentrations of NO₂ ranging from 200 ppb to 1000 ppb at 150 °C and under close to real conditions (25% relative humidity and 70% relative humidity). The MnO₂@GO sensors have shown a high response of 16.3% towards 1 ppm of NO₂ under dry conditions and a higher response of 44% at 70% RH towards the same concentration. Finally, it has also shown a strong sensitivity for NO₂. Full article

Molybdenum disulfide (MoS₂) is a promising catalyst for hydrogen evolution through water electrolysis with low cost and high efficiency, but its hydrogen evolution performance can be further improved. Using sodium molybdate (Na₂MoO₄·2H₂O) and thiourea (NH₂CSNH₂) as raw materials, MoS₂ was prepared by the hydrothermal method. Ni-doped MoS₂(Ni-MoS₂) was prepared by using nickel dichloride dihydrate (NiCl₂·2H₂O) as a Ni source and doping Ni into MoS₂ by the hydrothermal method. Under the conditions of different temperatures (190 °C, 200 °C, and 210 °C) and different Ni doping molar ratios (2%, 3%, and 4%), the optimum temperature and doping ratio of the prepared materials were explored by conducting a hydrogen evolution reaction (HER) by the electrolysis of water. The results showed that the optimum preparation temperature was 200 °C and the optimum molar ratio of Ni doping was 3%. Graphene oxide (GO) was obtained by oxidation of graphite (G), and then Ni-MoS₂/GO was prepared by the hydrothermal method with Ni-MoS₂ and GO. The performance of HER was tested. The materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), and X-ray photoelectron spectroscopy (XPS). The results show that the composite Ni-MoS₂/GO has good HER performance, which is better than that of MoS₂ or Ni-MoS₂. In 0.5 M H₂SO₄ solution, the η₁₀ is as low as 196 mV, the Tafel slope is 122 mV/dec, the C_dl is 13.98 mF/cm², and it has good stability. The enhancement of electrocatalytic activity is mainly due to the doping of a small amount of Ni, which increases the defects of the catalyst and forms more active sites. GO improves the conductivity of the material. Ni doping and GO compounding promote the HER performance of MoS₂. Full article

The demand for non-invasive, real-time health monitoring has driven advancements in wearable sensors for tracking biomarkers in sweat. Ammonium ions (NH₄⁺) in sweat serve as indicators of metabolic function, muscle fatigue, and kidney health. Although current ion-selective all-solid-state printed sensors based on nanocomposites typically exhibit good sensitivity (~50 mV/log [NH₄⁺]), low detection limits (LOD ranging from 10⁻⁶ to 10⁻⁷ M), and wide linearity ranges (from 10⁻⁵ to 10⁻¹ M), few have reported the stability test results necessary for their integration into commercial products for future practical applications. This study presents a highly stable, wearable electrochemical sensor based on a composite of metal–organic frameworks (MOFs) and reduced graphene oxide (rGO) for monitoring NH₄⁺ in sweat. The synergistic properties of Ni-based MOFs and rGO enhance the sensor’s electrochemical performance by improving charge transfer rates and expanding the electroactive surface area. The MOF/rGO sensor demonstrates high sensitivity, with a Nernstian response of 59.2 ± 1.5 mV/log [NH₄⁺], an LOD of 10^−6.37 M, and a linearity range of 10⁻⁶ to 10⁻¹ M. Additionally, the hydrophobic nature of the MOF/rGO composite prevents water layer formation at the sensing interface, thereby enhancing long-term stability, while its high double-layer capacitance minimizes potential drift (7.2 µV/s (i = ±1 nA)) in short-term measurements. Extensive testing verified the sensor’s exceptional stability, maintaining consistent performance and stable responses across varying NH₄⁺ concentrations over 7 days under ambient conditions. On-body tests further confirmed the sensor’s suitability for the continuous monitoring of NH₄⁺ levels during physical activities. Further investigations are required to fully elucidate the impact of interference from other sweat components (such as K⁺, Na⁺, Ca²⁺, etc.) and the influence of environmental factors (including the subject’s physical activity, posture, etc.). With a clearer understanding of these factors, the sensor has the potential to emerge as a promising tool for wearable health monitoring applications. Full article

Manganese dioxide (MnO₂) has drawn attention as a sensitiser to be incorporated in graphene-based chemoresistive sensors thanks to its promising properties. In this regard, a rGO@MnO₂ sensing material was prepared and deposited on two different substrates (silicon and Kapton). The effect of the substrate nature on the morphology and sensing behaviour of the rGO@MnO₂ material was thoroughly analysed and reported. These sensors were exposed to different dilutions of NO₂ ranging from 200 ppb to 1000 ppb under dry and humid conditions (25% RH and 70% RH) at room temperature. rGO@MnO₂ deposited on Kapton showed the highest response of 6.6% towards 1 ppm of NO₂ under dry conditions at RT. Other gases or vapours such as NH₃, CO, ethanol, H₂ and benzene were also tested. FESEM, HRTEM, Raman, XRD and ATR-IR were used to characterise the prepared sensors. The experimental results showed that the incorporation of nanosized MnO₂ in the rGO material enhanced its response towards NO₂. Moreover, this material also showed very good responses toward NH₃ both under dry and humid conditions, with the rGO@MnO₂ sensor on silicon showing the highest response of 18.5% towards 50 ppm of NH₃ under 50% RH at RT. Finally, the synthetised layers showed no cross-responsiveness towards other toxic gases. Full article

Sodium p-perfluorous nonenoxybenzene sulfonate (OBS) is one of the key alternatives to perfluoroalkyl substances (PFASs). Its widespread tendency has increased extensive contamination in the aquatic environment. However, the present treatment technology for OBS exhibited insignificant adsorption capacity and long adsorption time. In this study, three proportions (1:5, 3:5, and 10:1) of chitosan-modified amino-driven graphene oxide (CS-GO) were innovated to strengthen the OBS adsorption capacity, compared with graphene oxide (GO) and graphene (GH). Through the characterization of SEM, BET, and FTIR, it was discovered that CS was synthetized on GO surfaces successfully with a low specific surface area. Subsequently, batch single influence factor studies on OBS removal from simulated wastewater were investigated. The optimum removal efficiency of OBS could be achieved up to 95.4% within 2 h when the adsorbent was selected as CS-GO (10:1), the dosage was 2 mg, and the pH was 3. The addition of inorganic ions could promote the adsorption efficiency of OBS. In addition, CS-GO presented the maximum adsorption energy due to additional functional groups of -NH₃, and electrostatic interaction was the foremost motive for improving the adsorption efficiency of OBS. Moreover, OBS exhibited the fastest diffusion coefficient in the CS-GO-OBS solution, which is consistent with the fitting results of adsorption kinetics. Full article

This study proposes a feasible solution for boil-off gas (BOG) treatment to facilitate NH₃ fuel use by ocean-going ships, which is currently considered an alternative fuel for ships. Two systems were designed and analyzed for BOG in IMO Type-A NH₃ fuel storage tanks for 14,000 TEU container ships. First, BOG lost inside the storage tank minimized economic losses through the onboard re-liquefaction system. The total energy consumed by the system to process NH₃ gas generated in the fuel tank at 232.4 kg/h was 51.9 kW, and the specific energy consumption (SEC) was 0.223 kWh/kg. Second, NH₃ was supplied to the direct Low-Pressure Selective Catalytic Reduction (LP-SCR) system to treat marine pollutants generated by combustion engines. The feasible design point was determined by calculating the NH₃ feed flow rate using three methodologies. The energy consumed by the direct LP-SCR system was 3.89 and 2.39 kW, and the SEC was 0.0144 at 0.0167 kWh/kg at 100% and 25% load, respectively. The feasibility was indicated via economic analysis. Depending on the life cycle cost, the competitiveness of the re-liquefaction system depends on the price of NH₃, where a higher price yields a more economical solution. In conclusion, the direct LP-SCR system has a low overall cost because of its low energy consumption when supplying NH₃ and its reduced amount of core equipment. Full article

Sensitive determination of C-reactive protein (CRP) is of great significance because it is an early indicator of inflammation in cardiovascular disease and acute myocardial infarction. A disposable electrode with an integrated three-electrode system (working, reference, and counter electrodes) has great potential in the detection of biomarkers. In this work, an electrochemical immunosensing platform was fabricated on disposable and integrated screen-printed carbon electrode (SPCE) by introducing nanochannel arrays and gated electrochemical signals, which can achieve the sensitive detection of CRP in serum. To introduce active reactive groups for the fabrication of immuno-recognitive interface, vertically-ordered mesoporous silica-nanochannel film (VMSF) with rich amino groups (NH₂-VMSF) was rapidly grown by electrochemical assisted self-assembly (EASA). The electrochemically reduced graphene oxide (ErGO) synthesized in situ during the growth of NH₂-VMSF was used as a conductive adhesive glue to achieve stable bonding of the nanochannel array (NH₂-VMSF/ErGO/SPCE). After the amino group on the outer surface of NH₂-VMSF reacted with bifunctional glutaraldehyde (GA/NH₂-VMSF/ErGO/SPCE), the converted aldehyde surface was applied for covalent immobilization of the recognitive antibody (Ab) followed with the blocking of the non-specific sites. The fabricated immunosensor, Ab/GA/NH₂-VMSF/ErGO/SPCE, enables sensitive detection of CRP in the range from 10 pg/mL to 100 ng/mL with low limit of detection (LOD, 8 pg/mL, S/N = 3). The immunosensor possessed high selectivity and can realize reliable determination of CRP in human serum. Full article

Over the last decade, there has been extensive evidence that patients with inflammatory bowel disease from minority communities in the UK receive less than optimal care. In none of the studies has the role of surgery in the management of acute and severe ulcerative colitis been considered in any detail. A freedom of information (FOI) request was sent to 14 NHS Trusts in England, which serve significant South Asian populations. Details of the type of surgery patients from the South Asian and White British communities received between 2021 and 2020 were requested. Detailed responses were obtained from eight Trusts. Four hundred and ten White British patients underwent surgery for ulcerative colitis over this period at these eight Trusts, together with 67 South Asian patients. There was no statistically significant difference in the distribution across the types of surgery undergone by the two communities overall (χ² = 1.3, ns) and the proportions who underwent an ileo-anal anastomosis with pouch (z = −1.2, ns). However, within individual trusts, at the University Hospital Southampton NHS Foundation Trust, a significantly greater proportion of South Asian patients had an ileo-anal anastomosis with pouch compared to White British patients. At Cambridge University Hospitals NHS Foundation Trust, all 72 patients who underwent surgery for ulcerative colitis were White British. This study has shown that, in general, for patients with a severe flare of ulcerative colitis where medical treatment has failed and surgery is warranted, the nature of the procedures offered is the same in the White British and South Asian communities. However, of concern is the number of units with low volume procedures. For most Trusts reported in this study, the overall number of Ileo-anal pouch anastomosis or anastomosis of ileum to anus procedures performed over a number of years was substantially below that required for a single surgeon to achieve competence. These findings reinforce the argument that inflammatory bowel disease surgery should be performed in a limited number of high-volume centres rather than across a wide range of hospitals so as to ensure procedures are carried out by surgeons with sufficient and on-going experience. Full article

Monitoring environmental hazards and pollution control is vital for the detection of harmful toxic gases from industrial activities and natural processes in the environment, such as nitrogen dioxide (NO₂), ammonia (NH₃), hydrogen (H₂), hydrogen sulfide (H₂S), carbon dioxide (CO₂), and sulfur dioxide (SO₂). This is to ensure the preservation of public health and promote workplace safety. Graphene and its derivatives, especially reduced graphene oxide (rGO), have been designated as ideal materials in gas-sensing devices as their electronic properties highly influence the potential to adsorb specified toxic gas molecules. Despite its exceptional sensitivity at low gas concentrations, the sensor selectivity of pristine graphene is relatively weak, which limits its utility in many practical gas sensor applications. In view of this, the hybridization technique through heterojunction configurations of rGO with metal oxides has been explored, which showed promising improvement and a synergistic effect on the gas-sensing capacity, particularly at room temperature sensitivity and selectivity, even at low concentrations of the target gas. The unique features of graphene as a preferential gas sensor material are first highlighted, followed by a brief discussion on the basic working mechanism, fabrication, and performance of hybridized rGO/metal oxide-based gas sensors for various toxic gases, including NO₂, NH₃, H₂, H₂S, CO₂, and SO₂. The challenges and prospects of the graphene/metal oxide-based based gas sensors are presented at the end of the review. Full article

The development of new synthetic methods for methanol-tolerant catalysts with improved performance is of fundamental importance for the commercialization of fuel cells. Herein, we reported a facile displacement reaction-assisted synthesis of graphene-supported sub-nanometer Pt/Bi catalysts (Pt/Bi/rGO). Bismuth (0) nanoparticles produced by NH₃BH₃ reduction can be further dissolved into the ethylene glycol, implying Bi(0) has a strong interaction with the hydroxyl group. That is the key interaction between Bi(0) and the functional group on the rGO to form the ultra-small Bi/rGO catalyst. Furthermore, Pt clusters are obtained by the displacement between Bi(0) and HPtCl₄ and are directly anchored to the rGO surface. The as-synthesized Pt/Bi/rGO catalyst exhibits high oxygen reduction mass activity and high tolerance to methanol poisoning. In the presence of 0.5 mol/L CH₃OH, the initial potential and activity of ORR were almost unchanged, which demonstrated great potential in the application of direct methanol fuel cells. Full article

Reduced graphene oxide (rGO) has attracted enormous interest as a promising candidate material for gas detection due to its large specific surface areas. In our work, rGO films were fabricated on a large scale using dip-coating and spin-coating methods for the detection of nitrogen dioxide (NO₂) gas at room temperature. The influence of different test environments on the sensing performance, including the test atmosphere, gas flow and gas pressure was evaluated. The response time of the dip-coating method was 573 s with a long recovery period of 639 s and for the spin-coating method, the response time and recovery time was 386 s and 577 s, respectively. In addition, the spin-coated sensor exhibited high selectivity to NO₂, with the response increasing by more than 20% (for 15 ppm NO₂) as compared with that for HCHO, NH₃, and CH₄. Our results indicated that the spin coating method was more suitable for rGO-based gas sensors with higher performance. Full article

Water scarcity has become one of the most significant problems globally. Membrane technology has gained considerable attention in water treatment technologies. Polymeric nanocomposite membranes are based on several properties, with enhanced water flux, high hydrophilicity and anti-biofouling behavior, improving the membrane performance, flexibility, cost-effectiveness and excellent separation properties. In this study, aminated graphene oxide (NH₂-GO)-based PVDF membranes were fabricated using a phase-inversion method for textile dye removal. These fabricated membranes showed the highest water flux at about 170.2 (J/L.h⁻¹.m⁻²) and 98.2% BSA rejection. Moreover, these membranes removed about 96.6% and 88.5% of methylene blue and methyl orange, respectively. Aminated graphene oxide-based polyvinylidene fluoride (PVDF) membranes emerge as a good membrane material that enhances the membrane performance. Full article

Bacteria repellent surfaces and antibody-based coatings for bacterial assays have shown a growing demand in the field of biosensors, and have crucial importance in the design of biomedical devices. However, in-depth investigations and comparisons of possible solutions are still missing. The optical waveguide lightmode spectroscopy (OWLS) technique offers label-free, non-invasive, in situ characterization of protein and bacterial adsorption. Moreover, it has excellent flexibility for testing various surface coatings. Here, we describe an OWLS-based method supporting the development of bacteria repellent surfaces and characterize the layer structures and affinities of different antibody-based coatings for bacterial assays. In order to test nonspecific binding blocking agents against bacteria, OWLS chips were coated with bovine serum albumin (BSA), I-block, PAcrAM-g-(PMOXA, NH₂, Si), (PAcrAM-P) and PLL-g-PEG (PP) (with different coating temperatures), and subsequent Escherichia coli adhesion was monitored. We found that the best performing blocking agents could inhibit bacterial adhesion from samples with bacteria concentrations of up to 10⁷ cells/mL. Various immobilization methods were applied to graft a wide range of selected antibodies onto the biosensor’s surface. Simple physisorption, Mix&Go (AnteoBind) (MG) films, covalently immobilized protein A and avidin–biotin based surface chemistries were all fabricated and tested. The surface adsorbed mass densities of deposited antibodies were determined, and the biosensor;s kinetic data were evaluated to divine the possible orientations of the bacteria-capturing antibodies and determine the rate constants and footprints of the binding events. The development of affinity layers was supported by enzyme-linked immunosorbent assay (ELISA) measurements in order to test the bacteria binding capabilities of the antibodies. The best performance in the biosensor measurements was achieved by employing a polyclonal antibody in combination with protein A-based immobilization and PAcrAM-P blocking of nonspecific binding. Using this setting, a surface sensitivity of 70 cells/mm² was demonstrated. Full article

Over the last decade, there have been a number of studies which have documented disparate levels of care in the management of inflammatory bowel disease amongst various minority communities in the UK. Similar findings had previously been described in the USA, where access to biologics has been an issue. In this study, data on admissions to hospital of South Asian and White British patients with inflammatory bowel disease between 2015 and 2019 were collected from 12 National Health Service (NHS) trusts in England, three Health Boards in Wales and two Scottish health organizations using Freedom of Information requests. The analyses of data were based on the assumption that inflammatory bowel disease (IBD) has the same prevalence in the South Asian community and the White British community in the UK. Comparisons were made between the proportion of hospitalised patients who were South Asian and the proportion who were White British in the local community using a z statistic. In Leicester, Bradford, Croydon and Lothian, the proportion of patients from the South Asian community admitted to hospital was significantly greater than the proportion from the local White British community, which is consistent with the greater frequency and severity of the disease in the South Asian community in the UK. However, in Coventry, Wolverhampton, Walsall, Acute Pennine Trust in the north-west of England, Barking, Havering and Redbridge and Glasgow, South Asian patients were significantly under-represented, indicating significant issues with access to hospital-based healthcare for inflammatory bowel disease. This study provides evidence of on-going evidence of disparate levels of care for patients from a South Asian background, with inflammatory bowel disease being underserved by a number of NHS Trusts, Health Boards and comparable organisations. When there is on-going failure to achieve the objectives of the NHS of achieving equality in the delivery of care, it is critical to introduce effective policies which will alter the in-built inertia to change within such organisations. Full article

Tetracycline (TC) contamination in water has progressively exacerbated the environmental crisis. It is urgent to develop a feasible method to solve this pollution in water. However, polluted water often contains oil. This paper reported a glass fiber (FG)-assisted polyvinylidene fluoride (PVDF) hybrid membrane with dual functions: high TC degradation efficiency in emulsion and oil-water separation. It can meet the catalytic degradation of tetracycline in complex water. This membrane was decorated by coating the glass fiber with PVDF solution containing hydrophilic graphene oxide hybridized NH₂-MIL-101(Fe) particles. Moreover, due to its strong mechanical strength enhanced by the glass fiber, it can be reused as TC degradation catalysts for dozens of times without cracking. Thanks to the hydrophobicity of PVDF and the surface pore size of MOFs, the prepared membrane showed a good oil-water separation performance. Besides, the hydrophilic graphene oxide (GO) and NH₂-MIL-101(Fe) improved the membrane’s anti-fouling performance, allowing it to be reused as the separation membrane. Therefore, the outstanding stability and recoverability of the membrane make it as a fantastic candidate material for large-scale removal of TC as well as oil-water separation application. Full article