Influence of SiC Content on Microstructure, Dislocation Density and Mechanical Behavior of Cu/SiC Composite

The present investigation has examined the impact of micro-SiC on microstructure, dislocation and mechanical behavior of Cu/SiC composite. The micro-composite samples have been fabricated under a constant pressure (480 MPa) and sintered temperature (860oC) for 2 h. The sintering process was performed under argon gas. The microstructure examination was conducted using SEM/EDS and XRD diffraction. The SiC contents were 0, 5, 10,15,20,25 and 30 volume fraction. The outcomes showed that the density was significantly decreased with an increase of silicon carbide content. The relative densities of Cu and Cu/SiC composites was ranged from 91.24% to 83.56% for pure Cu and Cu/30 vol%SiC composites. The copper crystallite size was reduced with growing SiC content while the hardness, ultimate and yield compressive strength increased with increment of SiC volume fraction to 20% vol. The values of hardness, ultimate and yield compressive strength increased to 231 HV,343 and 176 N/mm2 , respectively for the composite sample containing 20% SiC particles with a percentage increase of 75%,26.6% and 57.2% compared with pure Cu.

Effect of Rice Straw on Tensile Properties of Tailings Cemented Paste Backfill

It is important and difficult to improve the tensile strength of backfill material to ensure the stability of goafs. In this study, rice straw (RS) in fiber form is used to improve the tensile properties of cemented paste backfill (CPB). An orthogonal experiment was designed, Brazilian indirect tensile strength tests were conducted to test the tensile performance of RS fiber-reinforced cemented paste backfill (RSCPB) under different fiber content (1, 2, 3 kg/m3) and fiber length (0.8~1, 1~3, 3~5 cm), and the microstructure of RSCPB was analyzed with scanning electron microscopy (SEM). The results showed that, compared with the conventional cemented paste backfill (CCPB), the increase in tensile strength of RSCPB ranged from 115.38% to 300.00% at 3 days curing age, 40.91% to 346.15% at 7 days, and −38.10% to 28.00% at 28 days., and the strain was slightly reduced during the curing period. The tensile strength, strain, and percentage increase of the RSCPB compared to the CCBP did not show a monotonic pattern of variation with the RS fiber content and length during the curing period. The RSCPB samples fractured under peak stress, showing obvious brittle failure. In addition, sulfate generated from S2− in the tailings inhibits the hydration reaction, and generates swelling products that form weak structural surfaces, which, in turn, lead to a 28-day tensile strength and strain of RSCPB lower than those at 7 days.

Mengembangkan Kerjasama Siswa dengan Media Pembelajaran PAPEDA

This study aims to enhance the cooperation of 5’th grade students in Kledokan Elementary School. To achieve that goal, Classroom Action Research (CAR) is carried out by learning on the mathematics course of data presentation materials using the Papan Pinball Penyajian Data (Papeda) media. The subjects of this study are 19 students of fifth grade in Kledokan Elementary School. Student cooperation data is obtained using an observation sheet. The indicators in this study are (1) helping each other in a group; (2) contributing to create a close group atmosphere; (3) acknowledge the strengths of friends in groups; (4) accepting the group decisions; and (5) actively participate in group assignments. This studies indicate an increase in student cooperation can be seen from the percentage increase in those indicators. Student's level of cooperation increase from 63,95% on cycle I to 90.79% on cycle II. It is concluded that the use of Papeda learning media able to enhance the coorperation of fifth grade in Kledokan Elementary School.

The effect of gadolinium-based contrast-agents on automated brain atrophy measurements by FreeSurfer in patients with multiple sclerosis

Objective To determine whether reliable brain atrophy measures can be obtained from post-contrast 3D T1-weighted images in patients with multiple sclerosis (MS) using FreeSurfer. Methods Twenty-two patients with MS were included, in which 3D T1-weighted MR images were obtained during the same scanner visit, with the same acquisition protocol, before and after administration of gadolinium-based contrast agents (GBCAs). Two FreeSurfer versions (v.6.0.1 and v.7.1.1.) were applied to calculate grey matter (GM) and white matter (WM) volumes and global and regional cortical thickness. The consistency between measures obtained in pre- and post-contrast images was assessed by intra-class correlation coefficient (ICC), the difference was investigated by paired t-tests, and the mean percentage increase or decrease was calculated for total WM and GM matter volume, total deep GM and thalamus volume, and mean cortical thickness. Results Good to excellent reliability was found between all investigated measures, with ICC ranging from 0.926 to 0.996, all p values < 0.001. GM volumes and cortical thickness measurements were significantly higher in post-contrast images by 3.1 to 17.4%, while total WM volume decreased significantly by 1.7% (all p values < 0.001). Conclusion The consistency between values obtained from pre- and post-contrast images was excellent, suggesting it may be possible to extract reliable brain atrophy measurements from T1-weighted images acquired after administration of GBCAs, using FreeSurfer. However, absolute values were systematically different between pre- and post-contrast images, meaning that such images should not be compared directly. Potential systematic effects, possibly dependent on GBCA dose or the delay time after contrast injection, should be investigated. Trial registration Clinical trials.gov. identifier: NCT00360906. Key Points • The influence of gadolinium-based contrast agents (GBCAs) on atrophy measurements is still largely unknown and challenges the use of a considerable source of historical and prospective real-world data. • In 22 patients with multiple sclerosis, the consistency between brain atrophy measurements obtained from pre- and post-contrast images was excellent, suggesting it may be possible to extract reliable atrophy measurements in T1-weighted images acquired after administration of GBCAs, using FreeSurfer. • Absolute values were systematically different between pre- and post-contrast images, meaning that such images should not be compared directly, and measurements extracted from certain regions (e.g., the temporal pole) should be interpreted with caution.

Violation of the use of traffic regulation means as a cause of a traffic accident

This article provides statistical data on the number of road accidents and their consequences (deaths and/or injuries) in all regions of Ukraine in 2021 as compared to the same period in 2020. Regions with a decrease in road traffic accident rates (Zakarpattya region, 9.6% decrease) and their percentage increase (Zhytomyr region, 56.1% increase) are highlighted. Based on the analysis of statistical data, it is estimated that the number of road traffic accidents in the country during this period increased by 19.6%. But as a positive phenomenon, the number of injuries and/or fatalities in these road accidents decreased by 17.2%. The article analyses and gives concrete examples of the use of some legally adopted road traffic control devices in the regional center of Ukraine - Zhytomyr city (traffic lights, road signs and road markings). Shows incidents of their use which are characterized by violations of traffic rules (Sections 8.1., 8.2, 8.3, 8.4, 8.7, Sections 33 "Traffic signs" and 34 "Traffic lanes"), DSTU 2587:2021 "Traffic lanes. General Technical Conditions", DSTU 4100:2021 "Road Safety. Road Signs". At the same time there are situations when road signs are in contradiction, which is categorically unacceptable. It also shows the cases where traffic signs are installed in a shape and design that is not included in traffic regulations and the relevant standard. It was concluded that the use of the above road traffic control devices in violation of the conditions of their installation (application) can lead to misinformation of road users, create additional informational and emotional pressure on them, contribute to increased fatigue, which consequently increases the probability of occurrence of road accidents and increases their importance.

Hydrodynamic Modelling of Floods and Estimating Socio-economic Impacts of Floods in Ugandan River Malaba Sub-catchment

River Malaba sub-catchment tends to experience dramatic flooding events, with several socio-economic impacts to the nearby communities, such as loss of lives and destructions of physical infrastructure. Analysis of spatiotemporal extents to which settlements, crops and physical infrastructures tend to be inundated are vital for predictive planning of risk-based adaptation measures. This paper presents a case study on flood risk assessment for Ugandan River Malaba sub-catchment. We applied the two-dimensional Hydraulic Engineering Center’s River Analysis System (2D HEC-RAS) for modelling of flooding extents. We considered extreme flow quantiles, lower and upper quantiles corresponding to the 95% confidence interval limits aimed at determining uncertainties in the flooding extents. Spatial extents of inundation on human settlement, land cover and infrastructure were analysed with respect to return periods of extreme flow quantiles. Finally, we estimated economic loss on infrastructure due to flooding. Results from the 2D HEC-RAS model were satisfactorily comparable with the results of observations. Amongst the land use types, cropland exhibited the highest vulnerability with at least 10,234.8 hectare (ha) susceptible to flooding event of 100-year return period (YRP). Inundated built-up land-use exhibited the highest vulnerability percentage increase (90%) between 2- and 100-YRP. In US Dollar, about US$ 33 million and US$ 39 million losses are estimated at 2- and 100-YRP, respectively, due to inundated rice gardens and these indicate a looming high risk of household food insecurity and poverty. Several infrastructure including 15 academic institutions, 12 health facilities, 32 worshiping places remain annually vulnerable to flooding. At least 6 km and 7 km of road network are also susceptible to flooding under extreme flows of return periods 2 and 100 years, respectively. Churches exhibited the highest economic losses of US$ 855,065 and US$ 1,623,832 at 2-YRP and 100-YRP, respectively. This study findings are relevant for planning the development of sustainable flood risk adaptation pathways given the established destructions within the sub-catchment due to flooding.

Implementation of a sedation protocol: a quality improvement project to enhance sedation management in the paediatric intensive care unit

BackgroundProper sedation is integral to ensuring the safety and comfort of children on mechanical ventilation (MV). Sedation protocols help to achieve this goal and reduce the duration of MV. We have observed varied sedation approaches, sedation score targets and sedative use by our physicians, which were manifested as oversedation and undersedation with associated accidental extubation. Hence, we aimed to implement a standardised sedation protocol and assess its impact on mechanically ventilated paediatric patients.MethodsA multidisciplinary quality improvement team was formed to develop and implement a standardised sedation protocol for mechanically ventilated paediatric patients. COMFORT-Behaviour (COMFORT-B) Scale score was used to assess the sedation targets and define undersedation, oversedation or adequate sedation. Our goal was to achieve adequate sedation during 90% of the sedation period. Based on the model for improvement methodology, we used plan–do–study–act cycles to develop, test and implement the new sedation protocol.ResultsThere was an immediate percentage increase in COMFORT-B Scale scores within the target sedation level, which was associated with a gradual decrease in the need for intermittent sedation doses over sedation infusion in the preimplementation, improvement and control phases (6.3, 4.9 and 3.1 sedation doses/12 hours/patient, respectively) to achieve adequate sedation target.ConclusionsThe standardisation of sedation protocols was safe and efficient, and improved the sedation quality in mechanically ventilated paediatric patients.

DEVELOPMENT OF STUDENT WORKSHEET WITH SAVI APPROACH TO IMPROVE MATHEMATICS REPRESENTATION ABILITIES IN CYLINDER MATERIALS

This research aimed to develop a valid, practical, and effective worksheets with SAVI approach and can improve students' mathematical representation skills on cylinder material. The method of this research was a Research and Development (R and D) through the development of 4-D (Define, Design, Develop, and Disseminate). This research was conducted at SMP Negeri 1 Pace. The subjects of this research was 32 students of class IX. The results of the validation of the LKS with SAVI approach by the validator get an assessment of 3.8 after experiencing product revision. This shows that the LKS with SAVI approach that was developed is declared valid. The results of the analysis of the practicality of the LKS with SAVI approach were declared practical with the percentage of student response questionnaires of 85.03% and from the teacher's observation sheet of 87.5%. LKS with SAVI approach succeeded in increasing students' representation ability with a percentage increase of 90.625%. The result of the percentage of product completeness is 71.875% so it can be said that the LKS product with SAVI approach is an effective product. These results indicate that worksheets with SAVI approach are considered valid, practical, effective, and can improve mathematical representation skills.

Moderating Effect of Illiquidity on The Relationship Between Momentum and Equity Returns in The Kenyan Capital Markets

This paper sought to examine the moderating effect of illiquidity on the relationship between momentum and equity returns in the Kenyan capital markets. Previous studies have shown that illiquidity has a time-varying effect on momentum strategies, but little is known whether illiquidity has a moderating effect on the relationship between momentum and equity returns in Kenyan capital markets. A longitudinal research design was used for this study to examine the causal inference. Data comprised of monthly transactions on the 20 equities used in the formulation of the NSE 20 share index over the period between Jan 2009 and up to March 2018 which formed 111 data points. ADF and PP results showed that Returns and momentum are stationary at levels while illiquidity was stationary at first difference. The error correction term was negative and statistically significant with or without the moderator. Results indicate that without a moderator percentage increase in momentum is linked to a 0.0000313% increase in returns in the short run. The study further shows that the effect of momentum on equity returns is moderated by illiquidity using a t-test. R2 changed from 0.427 to 0.4337 indicating a change of 0.006 at 0.05% significant level suggesting that illiquidity moderates the relationship between momentum and equity returns in the Kenyan capital markets.

Analysis of the Relationship Between the Content and Effectiveness of an Intervention based on the Layered Communication Model to Improve Communication

The Layered Communication Model (LCM) describes intersubjective development based on eight different communicative behaviors in three consecutive layers. Earlier studies showed that when the model is used in an intervention, the presence of many LCM behaviors increases from before to after the intervention. The present study aims to relate the content of the intervention to its effectiveness to learn whether and how the LCM can be used to improve communication. 15-minute videos of four student-teacher dyads were coded in ten-second intervals for the presence and absence of the eight LCM behaviors before, during and after the intervention. The intervention was divided into two phases: self-assessment and video feedback coaching. Intervention content was described based on the behaviors that were targeted for improvement during the two phases. Effectiveness was measured by calculating the percentage increase in presence between phases and by calculating effect sizes using a nonoverlap of all pairs method. Results showed that the second intervention phase (video feedback coaching) was most effective in terms of increasing the presence of LCM behaviors and creating larger effect sizes. Effectiveness measures decreased during the follow-up phase but were still higher than at baseline. Furthermore, effectiveness was higher for targeted behaviors than for untargeted behaviors. In conclusion, the LCM can be used as a tool to improve communication, especially when specific behaviors are clearly targeted and video feedback coaching is used to clarify how to work on improving the presence of those behaviors. The self-assessment phase needs adjustments to increase its effectiveness.