Primary 6 Students' Attitudes towards Mathematical Problem-Solving in a Problem-Based Learning Setting

Abstract: Research has indicated that student attitudes towards mathematics and mathematics learning can impact on mathematics achievement. While research has also indicated that unconventional pedagogies such as problem-based learning or cooperative learning may promote interest in student learning, the lack of evidence of the effects of these pedagogies in Singapore primary mathematics classrooms fuels the need to understand if these newer learning environments will promote positive attitudes. In this study, 80 Primary 6 students were surveyed to determine their attitudes towards solving mathematical modelling problems in a problem-based learning (PBL) setting after they had solved five modelling tasks. Contrary to a local study that suggests that Grade 7 students were not positive about solving challenging mathematics problems, results from the Attitudes Questionnaire show positive responses in the attributes of Interest, Perseverance, and Confidence, and suggesting that PBL can promote positive attitude in mathematics learning. Mixed-ability students registered higher, but statistically not significant, mean scores in these three areas than high-ability students. Students' open responses suggest that solving problems in a PBL setting is a promising pedagogic approach

Tensile, thermal and water absorption properties of corn stalk filled low density polyethylene composites: effect of coconut oil coupling agent

In this study, the corn stalk (CS) had been utilized as natural filler in low density polyethylene (LDPE). The effect of CS loading and coconut oil coupling agent (COCA) on tensile, thermal and water absorption properties of LDPE/CS composites were investigated. The increases of CS decreased the tensile strength and elongation at break of LDPE/CS composites, but increased in Young’s modulus. The incorporation of CS also contributed to high water uptake of LDPE/CS composites. However, the presence of CS has increased the crystallinity of composites and LDPE matrix due to nucleating effect. The addition of COCA has significantly increased the tensile strength, elongation at break, water resistivity and crystallinity of LDPE/CS composites, but slightly reduced in Young’s modulus. The scanning electron microscope (SEM) also evidence the presence of COCA improved the adhesion between CS and LDPE matrix

Crystallization of Adenylylsulfate Reductase from Desulfovibrio gigas: A Strategy Based on Controlled Protein Oligomerization

Adenylylsulfate reductase (adenosine 5′-phosphosulfate reductase, APS reductase or APSR, E.C.1.8.99.2) catalyzes the conversion of APS to sulfite in dissimilatory sulfate reduction. APSR was isolated and purified directly from massive anaerobically grown Desulfovibrio gigas, a strict anaerobe, for structure and function investigation. Oligomerization of APSR to form dimers–α_2β_2, tetramers–α_4β_4, hexamers–α_6β_6, and larger oligomers was observed during purification of the protein. Dynamic light scattering and ultracentrifugation revealed that the addition of adenosine monophosphate (AMP) or adenosine 5′-phosphosulfate (APS) disrupts the oligomerization, indicating that AMP or APS binding to the APSR dissociates the inactive hexamers into functional dimers. Treatment of APSR with β-mercaptoethanol decreased the enzyme size from a hexamer to a dimer, probably by disrupting the disulfide Cys156—Cys162 toward the C-terminus of the β-subunit. Alignment of the APSR sequences from D. gigas and A. fulgidus revealed the largest differences in this region of the β-subunit, with the D. gigas APSR containing 16 additional amino acids with the Cys156—Cys162 disulfide. Studies in a pH gradient showed that the diameter of the APSR decreased progressively with acidic pH. To crystallize the APSR for structure determination, we optimized conditions to generate a homogeneous and stable form of APSR by combining dynamic light scattering, ultracentrifugation, and electron paramagnetic resonance methods to analyze the various oligomeric states of the enzyme in varied environments

3D experimental study on a cylindrical floating breakwater system

The objective of the present study is to investigate the performance of a cylindrical floating breakwater system based on 3D experimental tests. The experiments were carried out in the wave basin (36 m*60 m*1.5 m)of the Ocean University of China. The cylindrical floating breakwater system consists of 10cylindrical floating breakwater units and 10mesh cages with balls in them, connected by 18 connectors and moored by a taut mooring system. The wave transmission coefficients, reflection coefficients, dissipation coefficients and motion responses of the floating breakwater are measured in both oblique and beam sea conditions. It is found that with the increase of the wavelength, both of the wave transmission coefficients and motion response amplitude of the FB system suffers an increase before it reaches its peak value, followed by a decrease trend. It can be concluded from the experiments that the proposed FB system has a satisfactory performance and it can be used to a wide range of sea conditions

Pediatric osteomyelitis due to rare tropical multi-drug resistance (MDR) organisms: a treatment quandary

Osteomyelits due to concurrent multi-drug resistance organisms is difficult to treat for any surgeon and infectious disease physician. An eleven-year-old boy presenting with an open fracture of the left radius and ulna after a fall in a stagnant wet field. Despite prophylactic antibiotics and surgical intervention, the open wound was infected, and Chromobacterium violaceum as well as Klebsiella pneumoniae were isolated. He was treated with six weeks of parenteral cefepime and amikacin and was discharged upon clinical improvement. Unfortunately, chronic osteomyelitis set in with persistent sinus drainage. He then underwent a second procedure for debridement of the wound and Burkholderia pseudomallei was isolated. Parenteral antibiotic therapy was initiated progressing with a marked improvement. However, the long course of antibiotics had exhausted the patient and his family, leading to a premature interruption of the parenteral antibiotic. Despite the suboptimal antibiotic course, there were no signs of relapsed osteomyelitis during subsequent review. The timely surgical intervention with appropriate sampling for subsequent microorganism isolation guided the suitability of the treatment line

Kimura’s disease: A clinicopathological study of 23 cases

IntroductionKimura’s disease (KD) is an uncommon lymphoproliferative fibroinflammatory disorder. Patients present with head and neck subcutaneous nodules with or without lymphadenopathy. Peripheral blood eosinophilia and elevated serum immunoglobulin E (IgE) levels are typical. This study was designed to delineate the clinicopathological features, pattern of care, and disease course of 23 Taiwanese patients with KD.MethodsWe retrospectively analyzed the clinical data of 23 consecutive cases (16 male and 7 female; age at diagnosis: 12–77 years) of KD diagnosed at our institution from 2015 to 2020.ResultsThe median time from presentation to diagnosis was 1 month. Twenty-one patients presented with unilateral or bilateral head and neck masses. The remaining two presented with right flank and right arm lesions, respectively. Peripheral blood eosinophilia was observed in nine, and elevated IgE levels were observed in four. All were diagnosed using either excisional or core-needle biopsy. Seven patients underwent fine needle aspiration without a diagnostic yield. Salivary gland and lymph node involvement was observed in three and seven patients, respectively. Most lesions showed tissue eosinophilia (100%) and florid follicular hyperplasia (78.26%). Three cases had histological KD-IgG4-RD overlap and three had comorbid IgG4-RD were recognized. Thirteen patients underwent surgical resection, one received adjuvant therapy, and two received prednisolone monotherapy.ConclusionKD should be considered in patients with subcutaneous masses, eosinophilia, and elevated IgE levels. Biopsy remains the gold standard of diagnosis. Increased recruitment of IgG4+ plasma cells is a common feature. Consideration of IgG4-RD in all KD patients may be prudent