Processing and Characterization of Mg Matrix Composites Reinforced with TiC and TiB2 Phases using an In-situ Reactive Infiltration Technique

Magnesium matrix composites are attractive for different applications especially in automotive and aerospace industries due to their superior specific properties. The main purpose of this work is to produce a new magnesium matrix composite reinforced with a network of TiC and TiB2 compounds via an in-situ reactive infiltration technique. In this process, the ceramic reinforcement phases, TiC and TiB2, were synthesized in-situ from the starting powders of Ti and B4C without any addition of a third metal powder such as Al. The molten magnesium infiltrates the preform of 3Ti-B4C by capillary forces. Furthermore, adding Mg or MgH2 powder with different weight percentages to the 3Ti-B4C preforms was used in an attempt to increase the Mg content in the fabricated composites. The results of the in-situ reaction mechanism investigation of the Ti-B4C and Mg-B4C systems show that the infiltrated magnesium not only infiltrates through the 3Ti-B4C preform and thus densifies the fabricated composite as a matrix metal, but also acts as an intermediary making the reaction possible at a lower temperature than that required for solid-state reaction between Ti and B4C and accelerates the reaction rate. The investigation of the in-situ reaction mechanism after adding Mg or MgH2 powder to the 3Ti-B4C preforms show that the reaction mechanisms are similar. However, the presence of the Mg or MgH2 in the preform accelerates the reaction rate making the reaction take place and finish in a shorter time. Also, the results of the parametric study show that the processing conditions such as temperature, holding time and green compact relative density have a significant influence on the reaction mechanism and the fabrication of the composite. Based on this work, it is recommended to fabricate the composite samples at 900ºC for 1.5 h and using a green compact of 70% relative density. The required equilibrium phases, TiCx and TiB2, formed in the composites with very small amounts of the residual Ti, boron carbide and intermediate phases such as TiB, Ti3B4 and MgB2. The fabrication of composites at these processing conditions avoids significant oxidation of Mg and formation of the ternary compound (Ti2AlC) in the cases of AZ91D or AM60B alloys composites, which can adversely affect the mechanical properties of the composites. Furthermore, the results reveal that the percentage of reinforcing phases, when the optimal processing parameters are used, can be tailored by controlling either the green compact relative density or the weight percentages of Mg or MgH2 powder added to the 3Ti-B4C preform. Microstructural characterization reveals a relatively uniform distribution of the reinforcing phases TiCx and TiB2 in the magnesium matrix. Mechanical properties of these composites such as elastic modulus, flexural and compressive strengths are greatly improved compared with those of the unreinforced Mg or Mg alloys. In contrast, the ductility of TiCx-TiB2/Mg composites is lower than that of the unreinforced Mg or Mg alloys. However, this lower ductility was improved by the addition of Mg or MgH2 powder in the preform. Secondary scanning electron microscopy was used to investigate the fracture surfaces after the flexural strength test. The composites show signs of mixed fracture; cleavage regions and some dimpling. In addition, microcracks observed in the matrix show that the failure might have initiated in the matrix rather than from the reinforcing particulates. Also, the results show that the hardness and the wear resistance of the composites are improved, compared with those of the unreinforced Mg alloy

The Reality of Employing Student-Centred Learning Strategies in Psychology Course from the Teachers’ Perspective in Kuwait

The present study aimed to explore the reality of employing student-centred learning strategies in psychology course from the teachers’ perspective in Kuwait. Those strategies are represented in the problem-based and project-based strategies.  The researcher selected a purposive sample that consists from 40 female and male teachers who teach psychology course. Those teachers were selected from 40 schools located in Al-Farwaniyah, Kuwait. Questionnaire forms were distributed to those teachers. All the forms were retrieved and deemed valid for analysis. SPSS software was employed for having the data analysed. It was found that the extent of employing the student-centred learning strategies (i.e. problem-based and project-based strategies) in psychology course from the teachers’ perspective in Kuwait in high. The researcher recommends conducting studies about the effectiveness of employing student-centred learning strategies in other courses in Kuwiat. Keywords: Student-centred strategies, psychology¸ Kuwait, teachers, reality. DOI: 10.7176/RHSS/10-22-01 Publication date: November 30th 202

Sustainable Cultivation of Truffles in Rural Regions of Finland

Truffles are rarely found in Finland, in spite of recent breakthroughs. In 2006, we initiated an effort to explore the possibility, and feasibility of truffle cultivation in Finland. This effort started by establishing the first truffle orchard in Juva. By 2016, we planted roughly 10 000 tree seedlings in 33 orchards. The results of our work indicated that even a boreal Finnish area is suitable for the sustainable organic production of truffles, and it appears that Tuber aestivum is a promising truffle species for future truffle orchards in northern conditions. Our results also show that restrictions caused by the Finnish winter climate and low soil temperatures can be overcome with proper soil and winter protection management. In conclusion, the selection of proper tree species and provenances is needed to obtain positive results from cultivating truffles in Finland as a future, sustainable and organic crop for the benefit of rural Finnish areas economic and activity

In silico characterization of bacterial chitinase : illuminating its relationship with archaeal and eukaryotic cousins

BackgroundChitin is one of the most abundant biopolymers on Earth, only trailing second after cellulose. The enzyme chitinase is responsible for the degradation of chitin. Chitinases are found to be produced by wide range of organisms ranging from archaea to higher plants. Though chitin is a major component of fungal cell walls and invertebrate exoskeletons, bacterial chitinase can be industrially generated at low cost, in facile downstream processes at high production rate. Microbial chitinases are more stable, active, and economically practicable compared to the plant- and animal-derived enzymes.ResultsIn the present study, computationally obtained results showed functional characteristics of chitinase with particular emphasis on bacterial chitinase which is fulfilling all the required qualities needed for commercial production. Sixty-two chitinase sequences from four different groups of organisms were collected from the RCSB Protein Data Bank. Considering one suitable exemplary sequence from each group is being compared with others. Primary, secondary, and tertiary structures are determined by in silico models. Different physical parameters, viz., pI, molecular weight, instability index, aliphatic index, GRAVY, and presence of functional motifs, are determined, and a phylogenetic tree has been constructed to elucidate relationships with other groups of organisms.ConclusionsThis study provides novel insights into distribution of chitinase among four groups and their characterization. The results represent valuable information toward bacterial chitinase in terms of the catalytic properties and structural features, can be exploited to produce a range of chitin-derived products.Peer reviewe

Superior mesenteric artery thrombosis in a child with chronic abdominal pain

We present a case of a 13 year old boy with global developmental delay, due to leukoencephalopathy, recent onset of epilepsy and faltering growth. There was a background of chronic abdominal pain, considered to be gastroesophageal reflux disease. He presented with an acute exacerbation of his abdominal pain, abdominal distention and shock. Ultimately a superior mesenteric artery thrombosis was diagnosed and treated. This report focusses on the clinical features of this case along with the diagnostic approach. It illustrates this serious and rare but treatable cause of chronic abdominal pain which can be suspected by careful history taking

Effect of A Probiotic Preparation on Gut Microbiota in Critically Ill Septic Patients Admitted to Intensive Care Unit: A Pilot Randomized Controlled Trial

Background: Sepsis promotes severe physiologic alterations in patients, and it has been reported to induce profound changes in the gut microbial composition. The decrease of ‘health‑benefiting’ microbes and the increase in dysbiosis in critically ill patients are thought to induce or aggravate sepsis. In this study, we aimed to explore the effect of a probiotic preparation, Lactocare®, on gut microbiota in critically ill septic patients admitted to the intensive care unit (ICU). Methods: Forty critically ill patients diagnosed with sepsis were assessed in this pilot randomized controlled trial. Patients were randomized into two groups: Lactocare and control groups. Patients in the Lactocare group received two capsules of Lactocare® for 10 days. Fecal samples were taken from all patients on days 1 and 10 for determining the gut microbial pattern. The primary outcome was gut microbial flora, and secondary outcomes were intensive care unit (ICU) length of stay and mortality. Results: Intragroup changes showed that all microbial flora considerably changed during the study period; the number of microbial flora significantly decreased in the control group and increased in the Lactocare group. Patients in the Lactocare group had a significantly lower incidence of diarrhea and infection with multidrug-resistant organisms. There was no difference in ICU length of stay in the Lactocare group compared to the control group (p= 0.289). The mortality rate was 30% in the control group compared to 20% in the Lactocare group (p: 0.465). Conclusion: This study showed a remarkable effect of the probiotic preparation on the gut microbiota in critically ill septic patients as it decreased the number of opportunistic pathogens. However, additional clinical research is needed to translate research into clinical practice to refine the clinical indication of the specific probiotic strains

Blockade of a chemokine, CCL2, reduces chronic colitis-associated carcinogenesis in mice

金沢大学がん研究所がん病態制御Accumulating evidence indicates the crucial contribution of chronic inflammation to various types of carcinogenesis, including colon carcinoma associated with ulcerative colitis and asbestosis-induced malignant mesothelioma. Ulcerative colitis-associated colon carcinogenesis can be recapitulated in mice by azoxymethane administration followed by repetitive dextran sulfate sodium ingestion. In the course of this carcinogenesis process, the expression of a macrophage-tropic chemokine, CCL2, was enhanced together with intracolonic massive infiltration of macrophages, which were a major source of cyclooxygenase (COX)-2, a crucial mediator of colon carcinogenesis. Mice deficient in CCL2-specific receptor, CCR2, exhibited less macrophage infiltration and lower tumor numbers with attenuated COX-2 expression. Moreover, CCL2 antagonists decreased intracolonic macrophage infiltration and COX-2 expression, attenuated neovascularization, and eventually reduced the numbers and size of colon tumors, even when given after multiple colon tumors have developed. These observations identify CCL2 as a crucial mediator of the initiation and progression of chronic colitis-associated colon carcinogenesis and suggest that targeting CCL2 may be useful in treating colon cancers, particularly those associated with chronic inflammation. ©2009 American Association for Cancer Research

Are Canadian General Internal Medicine training program graduates well prepared for their future careers?

BACKGROUND: At a time of increased need and demand for general internists in Canada, the attractiveness of generalist careers (including general internal medicine, GIM) has been falling as evidenced by the low number of residents choosing this specialty. One hypothesis for the lack of interest in a generalist career is lack of comfort with the skills needed to practice after training, and the mismatch between the tertiary care, inpatient training environment and "real life". This project was designed to determine perceived effectiveness of training for 10 years of graduates of Canadian GIM programs to assist in the development of curriculum and objectives for general internists that will meet the needs of graduates and ultimately society. METHODS: Mailed survey designed to explore perceived importance of training for and preparation for various aspects of Canadian GIM practice. After extensive piloting of the survey, including a pilot survey of two universities to improve the questionnaire, all graduates of the 16 universities over the previous ten years were surveyed. RESULTS: Gaps (difference between importance and preparation) were demonstrated in many of the CanMEDS 2000/2005(® )competencies. Medical problems of pregnancy, perioperative care, pain management, chronic care, ambulatory care and community GIM rotations were the medical expert areas with the largest gaps. Exposure to procedural skills was perceived to be lacking. Some procedural skills valued as important for current GIM trainees and performed frequently (example ambulatory ECG interpretation) had low preparation ratings by trainees. Other areas of perceived discrepancy between training and practice included: manager role (set up of an office), health advocate (counseling for prevention, for example smoking cessation), and professional (end of life issues, ethics). CONCLUSION: Graduates of Canadian GIM training programs over the last ten years have identified perceived gaps between training and important areas for practice. They have identified competencies that should be emphasized in Canadian GIM programs. Ongoing review of graduate's perceptions of training programs as it applies to their current practice is important to ensure ongoing appropriateness of training programs. This information will be used to strengthen GIM training programs in Canada