Effects of tutor-related behaviours on the process of problem-based learning

Tutors in a Problem-Based Learning (PBL) curriculum are thought to play active roles in guiding students to develop frameworks for use in the construction of knowledge. This implies that both subject-matter expertise and the ability of tutors to facilitate the learning process must be important in helping students learn. This study examines the behavioural effects of tutors in terms of subject-matter expertise, social congruence and cognitive congruence on students’ learning process and on their final achievement. The extent of students’ learning at each PBL phase was estimated by tracking the number of relevant concepts recalled at the end of each learning phase, while student achievement was based on students’ ability to describe and elaborate upon the relationship between relevant concepts learned. By using Analysis of Covariance, social congruence of the tutor was found to have a significant influence on learning in each PBL phase while all of the tutor-related behaviours had a significant impact on student achievement. The results suggest that the ability of tutors to communicate informally with students and hence create a less threatening learning environment that promotes a free flow exchange of ideas, has a greater impact on learning at each of the PBL phases as compared to tutors’ subject-matter expertise and their ability to explain concepts in a way that is easily understood by students. The data presented indicates that these tutor-related behaviours are determinants of learning in a PBL curriculum, with social congruence having a greater influence on learning in the different PBL phases

Performance of non-invasive tests and histology for the prediction of clinical outcomes in patients with non-alcoholic fatty liver disease: an individual participant data meta-analysis

BackgroundHistologically assessed liver fibrosis stage has prognostic significance in patients with non-alcoholic fatty liver disease (NAFLD) and is accepted as a surrogate endpoint in clinical trials for non-cirrhotic NAFLD. Our aim was to compare the prognostic performance of non-invasive tests with liver histology in patients with NAFLD.MethodsThis was an individual participant data meta-analysis of the prognostic performance of histologically assessed fibrosis stage (F0–4), liver stiffness measured by vibration-controlled transient elastography (LSM-VCTE), fibrosis-4 index (FIB-4), and NAFLD fibrosis score (NFS) in patients with NAFLD. The literature was searched for a previously published systematic review on the diagnostic accuracy of imaging and simple non-invasive tests and updated to Jan 12, 2022 for this study. Studies were identified through PubMed/MEDLINE, EMBASE, and CENTRAL, and authors were contacted for individual participant data, including outcome data, with a minimum of 12 months of follow-up. The primary outcome was a composite endpoint of all-cause mortality, hepatocellular carcinoma, liver transplantation, or cirrhosis complications (ie, ascites, variceal bleeding, hepatic encephalopathy, or progression to a MELD score ≥15). We calculated aggregated survival curves for trichotomised groups and compared them using stratified log-rank tests (histology: F0–2 vs F3 vs F4; LSM: 2·67; NFS: 0·676), calculated areas under the time-dependent receiver operating characteristic curves (tAUC), and performed Cox proportional-hazards regression to adjust for confounding. This study was registered with PROSPERO, CRD42022312226.FindingsOf 65 eligible studies, we included data on 2518 patients with biopsy-proven NAFLD from 25 studies (1126 [44·7%] were female, median age was 54 years [IQR 44–63), and 1161 [46·1%] had type 2 diabetes). After a median follow-up of 57 months [IQR 33–91], the composite endpoint was observed in 145 (5·8%) patients. Stratified log-rank tests showed significant differences between the trichotomised patient groups (p<0·0001 for all comparisons). The tAUC at 5 years were 0·72 (95% CI 0·62–0·81) for histology, 0·76 (0·70–0·83) for LSM-VCTE, 0·74 (0·64–0·82) for FIB-4, and 0·70 (0·63–0·80) for NFS. All index tests were significant predictors of the primary outcome after adjustment for confounders in the Cox regression.InterpretationSimple non-invasive tests performed as well as histologically assessed fibrosis in predicting clinical outcomes in patients with NAFLD and could be considered as alternatives to liver biopsy in some cases

Influence of impurities on the electrochemistry of carbon nanotubes and the toxicity of nanomaterials

Carbon nanomaterials such as carbon nanotubes and graphene are well recognized for their exceptional physical, structural and electronic properties that can be exploited for a wide range of electrochemical and biomedicine applications. Owing to the inherent electrocatalytic property of carbon nanotubes, their application as an electrochemical material has reportedly led to lowered overpotentials as well as enhanced redox reactions. However, all of these were elucidated to be due to the presence of metallic and carbonaceous impurities within carbon nanotubes which acted as electroactive sites. This project will expand on the influence of impurities on the electrochemistry of carbon nanotubes, and introduce an improved purification technique for an efficient removal of these impurities. With the subsequent discovery of graphene, their potential use in applications was modelled after carbon nanotubes. Along with the advent of graphene synthesis methods, numerous graphene-family nanomaterials were produced and these were explored for their use in numerous biomedicine applications. Consequently, concerns were raised about their possible nanotoxicological impact but the variations in their physiochemical properties have made it challenging to evaluate their toxicities. This project will investigate the toxicity effects of multiple derivatives of graphene, and this is also extended to include molybdenum sulfide which is another 2D material as well as nanomotors. All these are integral to the continuing efforts on nanosafety research as part of the rapid advancements in nanotechnology. ​Doctor of Philosophy (SPMS

In-situ infra-red spectroscopy of reduced forms of vitamin K1.

Infra-red spectra of the redox products of Vitamin K1 (VK1) were obtained in order to acquire information on the positions of their characteristic bands. We have investigated the reduction processes of VK1 in acetonitrile containing 0.2 M Bu4NPF6 as the supporting electrolyte with an amalgamation of electrochemistry techniques and in-situ infra-red spectroscopy. A spectroelectrochemical cell with a glass frit fitted at the bottom was used as the cathodic compartment to produce redox products and to allow monitoring of the electrolysis process simultaneously in the infra-red spectral range. In acetonitrile, two chemically reversible one-electron transfer reactions were detected via cyclic voltammetry and the E0 values obtained from it were used to determine the potentials for generating the reduced products during constant potential electrolysis. The reduction processes were also conducted at very low water concentrations and it was found that the second reduction step could not proceed due to the reduced forms undergoing adsorptive process with the electrode surface. The effect of water on the shifting of infra-red bands for both reduction processes was investigated and it was revealed that only bands belonging to the second reduced product were affected. The sequential addition low volumes of water (0 μL - 100 μL) to the VK1 in dry acetonitrile without Bu4NPF6 was discovered to cause a dramatic increase of approximately twenty-fold in the intensities of the absorbance bands belonging to VK1. Hydrogen bonding effect and solubility effect are the two plausible reasons deduced to explain the effects observed. The hydrogen bonding effect was investigated by using dimethyl terephthalate and VK1 model compound; and the solubility effect examined by using Vitamin E to find out which is responsible for the effect we observe on the intensities of the bands so as to have a better understanding of how VK1 is able to interact with water.Bachelor of Science in Chemistry and Biological Chemistr

The toxicity of graphene oxides : dependence on the oxidative methods used

Graphene, a class of two-dimensional carbon nanomaterial, has attracted extensive interest in recent years, with a significant amount of research focusing on graphene oxides (GOs). They have been primed as potential candidates for biomedical applications such as cell labeling and drug delivery, thus the toxicity and behavior of graphene oxides in biological systems are fundamental issues that need urgent attention. The production of GO is generally achieved through a top-down route, which includes the usage of concentrated H2SO4 along with: 1) concentrated nitric acid and KClO3 oxidant (Hoffmann); 2) fuming nitric acid and KClO3 oxidant (Staudenmaier); 3) concentrated phosphoric acid with KMnO4 (Tour); or 4) sodium nitrate for in-situ production of nitric acid in the presence of KMnO4 (Hummers). It has been widely assumed that the properties of these four GOs produced by using the above different methods are roughly similar, so the methods have been used interchangeably. However, several studies have reported that the toxicity of graphene-related nanomaterials in biological systems may be influenced by their physiochemical properties, such as surface functional groups and structural defects. In addition, considering how GOs are increasingly used in the field of biomedicine, we are interested to see how the oxygen content/functional groups of GOs can impact their toxicological profiles. Since in-vitro testing is a common first step in assessing the health risks related with engineered nanomaterials, the cytotoxicity of the GOs prepared by the four different oxidative treatments was investigated by measuring the mitochondrial activity in adherent lung epithelial cells (A549) by using commercially available viability assays. The dose–response data was generated by using two assays, the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and the water-soluble tetrazolium salt (WST-8). From the viability data, it is evident that there is a strong dose-dependent cytotoxic response resulting from the four GO nanomaterials tested after a 24 h exposure, and it is suggested that there is a correlation between the amounts of oxygen content/functional groups of GOs with their toxicological behavior towards the A549 cells

Nanographite impurities in carbon nanotubes : their influence on the oxidation of insulin, nitric oxide, and extracellular thiols

There has been growing interest in the use of modified-carbon-nanotube electrodes in applications such as the electrochemical detection of biologically significant compounds, owing to their apparent “electrocatalytic” properties and ability to enhance oxidative signals. In spite of their salient properties, little work has been done to further examine the reasons for these reported characteristics. In this report, we present clear evidence that the presence of nanographite impurities within carbon nanotubes (CNTs) is responsible for providing the previously reported enhanced electrochemical response. We have demonstrated this effect on homocysteine, N-acetyl-l-cysteine, nitric oxide, and insulin, which are important biological agents in the body. Moreover, we also showed that the influence of nanographite impurities on the electrochemistry of carbon nanotubes is prevalent among a variety of CNTs, such as single-walled CNTs, double-walled CNTs, and few-walled CNTs. Our findings will have a profound influence upon the biomedical applications of CNTs

Impurities in graphenes and carbon nanotubes and their influence on the redox properties

Carbon nanomaterials, such as carbon nanotubes and graphene-related materials are currently being heavily researched and widely proposed for numerous applications. It is often underestimated that these carbon nanomaterials are of complex nature, consisting of different components and often containing impurities. These impurities can dramatically influence, or even dominate various properties of carbon nanotubes and graphenes. Herein, we will show that impurities in such carbon nanomaterials are capable of exhibiting a striking effect on their redox properties. The impurities being discussed include metallic, nanographitic and amorphous carbon-based impurities commonly found in carbon nanotube samples; and metallic, nanographitic, and carbonaceous debris-based impurities in graphenes. We emphasize that the effects brought about by these impurities on the properties of the carbon nanomaterials can, in many cases be rather significant. As such, one needs to be cautious by clearly accounting for these effects observed for the nanomaterials before assigning any properties to the material itself

Is learning in problem-based learning cumulative?

Problem-based learning (PBL) is generally organized in three phases, involving collaborative and self-directed learning processes. The hypothesis tested here is whether learning in the different phases of PBL is cumulative, with learning in each phase depending on that of the previous phase. The scientific concepts recalled by 218 students at the end of each PBL phase were used to estimate the extent of students’ learning. The data were then analyzed using structural equation modeling. Results show that our hypothesized model fits the data well. Alternative hypotheses according to which achievement is predicted either by collaborative learning alone or by self-directed learning alone did not fit the data. We conclude that the learning in each PBL phase is cumulative, and strongly influenced by the earlier phase, thus providing support for the PBL cycle of problem analysis, self-directed learning, and a subsequent reporting phase. We also demonstrate an efficient method to capture and quantify students’ learning during the PBL process

Cytotoxicity profile of highly hydrogenated graphene

Graphene and its graphene-related counterparts have been considered the future of advanced nanomaterials owing to their exemplary properties. An increase in their potential applications in the biomedical field has led to serious concerns regarding their safety and impact on health. To understand the toxicity profile for a particular type of graphene utilized in a given application, it is important to recognize the differences between the graphene-related components and correlate their cellular toxicity effects to the attributed physiochemical properties. In this study, the cytoxicity effects of highly hydrogenated graphene (HHG) and its graphene oxide (GO) counterpart on the basis of in vitro toxicological assessments are reported and the effects correlated with the physiochemical properties of the tested nanomaterials. Upon 24 h exposure to the nanomaterials, a dose-dependent cellular cytotoxic effect was exhibited and the HHG was observed to be more cytotoxic than its GO control. Detailed characterization revealed an extensive C[BOND]H sp3 network on the carbon backbone of HHG with few oxygen-containing groups, as opposed to the presence of large amounts of oxygen-containing groups on the GO. It is therefore hypothesized that the preferential adsorption of micronutrients on the surface of the HHG nanomaterial by means of hydrophobic interactions resulted in a reduction in the bioavailability of nutrients required for cellular viability. The nanotoxicological profile of highly hydrogenated graphene is assessed for the first time in our study, thereby paving the way for further evaluation of the toxicity risks involved with the utilization of various graphene-related nanomaterials in the real world