Clinical reasoning gains in medical PBL: an UMLS based tutoring system

Problem based learning is becoming widely popular as an effective teaching method in medical education. Paying individual attention to a small group of students in medical problem-based learning (PBL) can place burden on the workload of medical faculty whose time is very costly. Intelligent tutoring systems offer a cost effective alternative in helping to train the students, but they are typically prone to brittleness and the knowledge acquisition bottleneck. Existing tutoring systems accept a small set of approved solutions for each problem scenario stored into the system. Plausible student solutions that lie outside the scope of the explicitly encoded ones receive little acknowledgment from the system. Tutoring hints are also confined to the knowledge space of the approved solutions, leading to brittleness in the tutoring approach. We report the clinical reasoning gains off a tutoring system for medical PBL that employs and represents the widely available medical knowledge source UMLS as the domain ontology. We exploit the structure of the concept hierarchy to expand the plausible solution space and generate hints based on the problem solving context. Evaluation of student learning outcomes led to highly significant learning gains (Mann-Whitney, p < 0.001).     

Synthesis and characterization of poly(lactic acid)/ montmorillonite nanocomposites by in situ polycondensation catalyzed by non-metal-based compound

Poly(lactic acid)/montmorillonite nanocomposites were prepared by using non-toxic catalysts, i.e., phthalic acid and succinimide, via in situ polycondensation in presence of silicate. Concentrations of catalysts and clay were varied in a range of 0-3% wt and 0-0.5% wt, respectively. The reaction condition was controlled at 180 degrees C for 24 hr under a reduced pressure. Viscosity average molecular weight of the synthesized polymers and nanocomposites were characterized and compared using an Ubbelohde viscometer. Pattern of silicate distribution in the composites was investigated by X-ray diffraction to correlate with thermal properties evaluated by differential scanning calorimetry and thermogravimetric analysis. The results showed that the addition of catalysts at 2% wt gave the highest product yield (55-60%). The presence of silicate affected on molecular weight reduction, and the diffracted patterns suggested an intercalated structure. With a small amount of added filler, a significant improvement in thermal property and crystallinity of the resultant composites was obtained compared to those of the catalyzed polymers, in which the composites with succinimide exhibited overall better thermal stability and higher crystallinity than the ones prepared with phthalic acid.     

Development of antimicrobial coating by later-by-layer dip coating of chlorhexidine-loaded micelles

Layer-by-layer (LbL) dip coating, accompanying with the use of micelle structure, allows hydrophobic molecules to be coated on medical devices’ surface via hydrogen bonding interaction. In addition, micelle structure also allows control release of encapsulated compound. In this research, we investigated methods to coat and maximize the amount of chlorhexidine (CHX) on silicone surface through LbL dip coating method utilizing hydrogen bonding interaction between PEG on micelle corona and PAA. The number of coated cycles was varied in the process and 90 coating cycles provided the maximum amount of CHX loaded onto the surface. In addition, pre-coating the surface with PAA enhanced the amount of coated CHX by 20%. Scanning electron microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) were used to validate and characterize the coating. For control release aspect, the coated film tended to disrupt at physiological condition; hence chemical crosslinking was performed to minimize the disruption and maximize the release time. Chemical crosslinking at pH 2.5 and 4.5 were performed in the process. It was found that chemical crosslinking could help extend the release period up to 18 days. This was significantly longer when compared to the non-crosslinking silicone tube that could only prolong the release for 5 days. In addition, chemical crosslinking at pH 2.5 gave higher and better initial burst release, release period and antimicrobial properties than that of pH 4.5 or the normal used pH for chemical crosslinking process.     

Nitrogen compounds removal in a packed bed external loop airlift bioreactor

A packed bed external loop airlift bioreactor (PBELAB) was proposed as an alternative treatment system for wastewater containing ammonia and nitrate compounds. The 60L PBELAB consisted of aeration and non-aeration zones, both of which were packed with plastic bioballs to enhance the surface area for the attachment of bacteria. The system was able to achieve complete removal of all nitrogen compounds with simultaneous nitrification and denitrification, i.e., ammonia was decomposed in the aeration zone and nitrate was biodegraded in the non-aeration zone. At normal operation, the nitrification rate obtained from the system was in the range of 0.14-0.87 gNH₃-N/m²d and the denitrification rate was 0.04 gNO₃-N/m²d. The factors found to have great influence on the system included dissolved oxygen concentration and biofilm thickness. In addition, PBELAB was proven to perform well under nitrate shock load condition.     

Preparation of bio-based nanocomposite emulsions: Effect of clay type

Bio-based nanocomposite latexes were prepared by emulsification–diffusion method. Two kinds of silicate, sodium and organo-modified montmorillonites, were compared and clay concentrations were varied at 1–6 wt%. The resultant particles were characterized in terms of particle size, particle morphology, and zeta potential. Silicate dispersion in the polymer matrix was evaluated by X-ray diffractometry and transmission electron microscopy, while thermal properties of the resultant nanocomposite films were also investigated by differential scanning calorimetry and thermogravimetry. The average particle sizes of the emulsions were found in the range of 20–30 μm, whereas zeta potentials of the particles were obtained in the range from −37 to −60 mV, depending on the silicate type and content. X-ray diffraction patterns combined with micrographs indicated that the silicates were effectively distributed in the polymer matrix where extensive exfoliation and partial intercalation were present. Thermal properties of the nanocomposite films were significantly improved compared to those of the unfilled film. Thermal stability tended to increase in accordance with clay content for both types of silicate, in which the highest shift of degradation temperature was obtained with the sodium montmorillonite filled nanocomposite film at the maximum loading content (6 wt%).     

Eco-friendly high-performance coating for polyester fabric

Due to increasing environmental concerns and depletion of petroleum resources, the use of green materials has become popular with garment industry. In the past, natural rubber, which is one of the most prevalent bio-based elastomers, was used as waterproof coating for many applications due to its inherent elasticity, high tear and abrasion resistance, and hydrophobicity. However, NR has significant drawbacks when applying to garments including its poor adhesion to polyester fabrics and low breathability. Polyurethane, on the other hand, possesses high breathability but relatively poor elasticity. In this study, the fabric coating based on waterborne polyurethane and pre-vulcanized natural rubber latex was synthesized with the goal to produce fabric for high-performance applications, which could surpass criteria including water vapor permeability (WVP) (>10 000 g/m²•24hr), water pressure resistance (WPR) (>1000 mmH₂O), and stretchability (>300%). The best condition achieved when using 60NR cured for 15 min by using 1.5 phr sulfur could provide WPR value of 4090 mmH₂O and WVP of 11 033 g/m²•24hr. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48002.     

Modeling individual and collaborative problem-solving in medical problem-based learning

Today a great many medical schools have turned to a problem-based learning (PBL) approach to teaching as an alternative to traditional didactic medical education to teach clinical-reasoning skills at the early stages of medical education. While PBL has many strengths, effective PBL tutoring is time-intensive and requires the tutor to provide a high degree of personal attention to the students, which is difficult in the current academic environment of increasing demands on faculty time. This paper describes the student modeling approach used in the COMET intelligent tutoring system for collaborative medical PBL. To generate appropriate tutorial actions, COMET uses a model of each student’s clinical reasoning for the problem domain. In addition, since problem solving in group PBL is a collaborative process, COMET uses a group model that enables it to do things like focus the group discussion, promote collaboration, and suggest peer helpers. Bayesian networks are used to model individual student knowledge and activity, as well as that of the group. The validity of the modeling approach has been tested with student models in the areas of head injury, stroke, and heart attack. Receiver operating characteristic (ROC) curve analysis shows that the models are highly accurate in predicting individual student actions. Comparison with human tutors shows that the focus of group activity determined by the model agrees with that suggested by the majority of the human tutors with a high degree of statistical agreement (McNemar test, p = 0.774, Kappa = 0.823).     

Properties and bioavailability assessment of shrimp astaxanthin loaded liposomes

Food Science and Biotechnology - This study aimed to investigate the effects of phospholipid composition on the properties and bioavailability of astaxanthin-loaded liposomes using cell culture....