Graphene made easy: high quality, large-area samples

We show that by using an original method, bulk graphite can be bonded onto borosilicate glass or potentially any insulating substrate with ionic conductivity and then cleaved off to leave single or few layer graphene on the substrate, identified optically and with Raman spectroscopy. This simple, inexpensive and fast method leads to the preparation of large area graphene and single or few-layer films of layered materials in general. We have prepared mm size few-layer graphene samples and also measured I-V characteristics in a FET. This opens up perspectives both for fundamental research as well as for applications.Comment: 11 pages, 4 figures,Solid State Communications, In pres

Impact of COVID-19 Pandemic on Postgraduate Training in Pediatrics

Objective: To assess the impact of the coronavirus disease-2019 pandemic on paediatric postgraduate training as perceived by the trainees. Method: The cross-sectional exploratory study was conducted at the Department of Paediatrics, King Edward Medical University, Lahore, Pakistan, from May to June 2020, and comprised paediatric postgraduate trainees associated with various hospitals across the country who were approached online with a pre-designed 24-item questionnaire during the peak months of the pandemic. Data was analysed using SPSS 25. Results: Of the 226 postgraduates, 134(59.2%) were females. The overall mean age was 28.85±3.06 years. Of the total, 200(88.5%) and 195(86.2%) reported that pandemic had adversely impacted their training and research. The number of trainees managing >30 patients and doing >5 procedures per week before the pandemic decreased from 126(55.8%) and 150(66.4%) to 38(16.8%) and 41(18.1%), respectively, during the pandemic (p=0.01). Regarding e-learning, 168(74.3%) trainees thought it might partly compensate for training, 135(59.7%) showed readiness for it, and 179(79.2%) believed this could not replace actual patient interaction. Conclusion: The coronavirus disease-2019 pandemic was found to have adversely impacted paediatric postgraduate training. Key Words: COVID-19, Paediatrics, Impact, Postgraduate, Training

Structural and Optical Characteristics of Highly UV-Blue Luminescent ZnNiO Nanoparticles Prepared by Sol–Gel Method

A simple single pot sol–gel method is used to prepare ZnNiO nanoparticles at assorted Ni doping levels, 1, 3, 7 and 10 wt.%. Structural and optical properties of nanoparticles are studied by X-ray diffraction (XRD), UV–visible diffuse reflection spectroscopy (DRS), photoluminescence (PL) measurements, scanning electron microscopy (SEM), μ-Raman and X-ray photoelectron-spectroscopy (XPS). A single substitutional solid solution phase is detected in the wurtzite ZnNiO nanoparticles at various doping levels. XRD peak splitting and shifting is ascribed to reduced wurtzite character and presence of crystalline strain in nanoparticles at higher level of Ni doping. The Kubelka-Munk function of DRS data reveals the presence of the Burstein-Moss effect in the optical absorption of ZnNiO nanoparticles. Photoluminescence studies show intense UV-blue emission from ZnNiO nanoparticles. The UV PL also exhibits the Burstein-Moss blue shift in the ZnNiO luminescence. Raman analyses also confirms the wurtzite structure of ZnNiO nanoparticles; however, crystal structural defects and bond stiffness increase with Ni doping. The optical and structural studies presented in this work are pointing towards a multivalent Ni substitution in the nanoparticles

Cement-Stabilized Waste Sand as Sustainable Construction Materials for Foundations and Highway Roads

In this study, cement-treated waste sand as a by-product material produced from Al-Ahsa quarries (Saudi Arabia) was experimentally tested and investigated as a base course material for the foundation of structures and roads. The study aimed to use the waste sand as a construction material by improving its strength, bearing capacity, and stiffness. The waste sand was mixed with different percentages of Portland cement content (0, 2, 4, 6, and 8%) at the maximum dry density and optimum water content of the standard Proctor compaction conditions of a non-treated sample. Unconfined compressive strength and California Bearing Ratio (CBR) tests for different curing times were conducted. X-ray diffraction (XRD), laser-scanning microscopy (LSM), and X-ray spectroscopy (XPS) were used to explore the microstructure and composition of the treated sand. The results showed that the compressive strength, initial tangent modulus, and CBR of the treated sand increase with the increase in cement content and curing time. Furthermore, good correlations were established among the strength, initial tangent modulus, and CBR. Based on the obtained results, cement-stabilized waste sand is a potential material for use in construction. This is expected to save the environment and reduce the cost of road construction

Palladium-loaded cucurbit[7]uril-modified iron oxide nanoparticles for C-C cross-coupling reactions

International audienc

Influence of Lime and Volcanic Ash on the Properties of Dune Sand as Sustainable Construction Materials

This study focused on evaluating dune sand stabilized with lime and volcanic ash as base course materials in engineering construction. Dune sands are found in Saudi Arabia in huge quantities. Due to the high demand for construction materials, this makes them highly suitable for construction. A testing program was designed to investigate the effect of adding different percentages by weight of lime (L: 0, 2, 4, and 6%) and volcanic ash (VA: 0, 1, 3, and 5%) on the engineering properties of the stabilized mixture. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted. In addition, Raman spectroscopy and laser-scanning microscopy (LSM) tests were performed to explore the chemical characteristic, packing, and structure of the mixture. The results showed that the UCS, CBR, and the Young’s modulus (Es) of the treated dune sand increased with the increase in percentage of both stabilizers. Furthermore, LSM images of mortar blended with intermediate L-to-VA blend ratio ≈0.55 (L: 6% and VA: 5%) exhibit compact packing of sand grains, indicating strong adhesion and higher cementing value. The results of the study are promising and encourage using the treated dune sand in engineering construction even with a low percentage use of lime (2%) and volcanic ash (1–3%) as stabilizers

Influence of Lime and Volcanic Ash on the Properties of Dune Sand as Sustainable Construction Materials

This study focused on evaluating dune sand stabilized with lime and volcanic ash as base course materials in engineering construction. Dune sands are found in Saudi Arabia in huge quantities. Due to the high demand for construction materials, this makes them highly suitable for construction. A testing program was designed to investigate the effect of adding different percentages by weight of lime (L: 0, 2, 4, and 6%) and volcanic ash (VA: 0, 1, 3, and 5%) on the engineering properties of the stabilized mixture. Unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were conducted. In addition, Raman spectroscopy and laser-scanning microscopy (LSM) tests were performed to explore the chemical characteristic, packing, and structure of the mixture. The results showed that the UCS, CBR, and the Young’s modulus (Es) of the treated dune sand increased with the increase in percentage of both stabilizers. Furthermore, LSM images of mortar blended with intermediate L-to-VA blend ratio ≈0.55 (L: 6% and VA: 5%) exhibit compact packing of sand grains, indicating strong adhesion and higher cementing value. The results of the study are promising and encourage using the treated dune sand in engineering construction even with a low percentage use of lime (2%) and volcanic ash (1–3%) as stabilizers

Extraction of Hydroxyapatite from Camel Bone for Bone Tissue Engineering Application

Waste tissues such as mammalian bone are a valuable source from which to extract hydroxyapatite. Camel bone-based hydroxyapatite (CBHA) was extracted from the femur of camel bones using a defatting and deproteinization procedure. The extracted CBHA was mechanically, chemically, physically, morphologically and structurally characterized. Fourier-Transform Infra-Red (FTIR) spectra, Micro-Raman, and X-ray diffraction analysis confirmed successful extraction of hydroxyapatite. The mechanical properties of the CBHA scaffold were measured using a Universal Instron compression tester. Scanning electron microscopy showed the presence of a characteristic interconnected porous architecture with pore diameter ranging from 50–600 µm and micro-computer tomography (Micro-CT) analysis identified a mean porosity of 73.93. Thermogravimetric analysis showed that the CBHA was stable up to 1000 °C and lost only 1.435% of its weight. Inductively coupled plasma–mass spectrometry (ICP-MS) and Energy-dispersive-X-ray (EDX) analysis demonstrated the presence of significant amounts of calcium and phosphorus and trace ions of sodium, magnesium, zinc, lead and strontium. Following 21 days of incubation in simulated body fluid (SBF), the pH fluctuated between 10–10.45 and a gradual increase in weight loss was observed. In conclusion, the extracted CBHA is a promising material for future use in bone tissue regeneration applications