Impact of Thermal Aging on the Microstructure Evolution and Mechanical Properties of Lanthanum-Doped Tin-Silver-Copper Lead-Free Solders

The authors would like to thank Ste´phanie Blanc (Electrical Engineer at Schlumberger) for her useful contribution to the project, Claude Guyomard and Olivier Naegelen (Arts et Me´tiers ParisTech) for the die design and sample casting, respectively, and Jean-Marc Raulot for his enriching discussions.An extensive study is made to analyze the impact of pure lanthanum on the microstructure and mechanical properties of Sn-Ag-Cu (SAC) alloys at high temperatures. Different compositions are tested; the temperature applied for the isothermal aging is 150 C, and aging times of 10 h, 25 h, 50 h, 100 h, and 200 h are studied. Optical microscopy with cross-polarized light is used to follow the grain size, which is refined from 8 mm to 1 mm for as-cast samples and is maintained during thermal aging. Intermetallic compounds (IMCs) present inside the bulk Sn matrix affect the mechanical properties of the SAC alloys. Due to high-temperature exposure, these IMCs grow and hence their impact on mechanical properties becomes more significant. This growth is followed by scanning electron microscopy, and energy-dispersive spectroscopy is used for elemental mapping of each phase. A significant refinement in the average size of IMCs of up to 40% is identified for the as-cast samples, and the coarsening rate of these IMCs is slowed by up to 70% with no change in the interparticle spacing. Yield stress and tensile strength are determined through tensile testing at 20 C for as-cast samples and after thermal aging at 150 C for 100 h and 200h. Both yield stress and tensile strength are increased by up to 20% by minute lanthanum doping

Transformational leadership, knowledge management, entrepreneurial orientation and organisational excellence in the higher education institutions in Nigeria

The past three decades had witnessed increasing challenge to the higher education institutions especially the public-owned ones. This challenge had been for the institutions to think like the corporate enterprises towards becoming world class so as to ensure improved excellent performances. However, there had been little research on the impact of transformational leadership and knowledge management as well as the moderating role of entrepreneurial orientation on performance excellence of higher education institutions especially in Nigeria. Based on the Resource Based View and Complementary Asset Theory, this study thereby aimed to determine the significance of relationship between transformational leadership and organisational excellence, and the significance of relationship between knowledge management and organisational excellence in the public higher education institutions in Nigeria. The study further aimed to determine the moderating role of entrepreneurial orientation on the relationship between transformational leadership and organisational excellence, and on the relationship between knowledge management and organisational excellence. Data were collected from division heads in the public higher education institutions in the North-Central and South-Western geo-political zones of Nigeria. The study employed multistage sampling procedure with the use of survey questionnaires. Out of the 480 questionnaires distributed, 383 were returned with only 372 usable giving a 77.5 percent response rate. The 372 usable responses were analyzed through SPSS 20.0. Multiple regressions were used to investigate the relationships between transformational leadership, knowledge management, entrepreneurial orientation and organisational excellence. Results showed significant positive relationships between transformational leadership and organisational excellence and between knowledge management and organisational excellence. The results also showed that entrepreneurial orientation moderates the relationship between transformational leadership and organisational excellence, and that of knowledge management and organisational excellence

Surgical management of mallet finger with extension block pinning

Background: Various surgical and nonsurgical treatments have been described in the management of mallet finger. The purpose of this study is to evaluate the effectiveness of extension block pinning in the management of displaced mallet finger fractures.Methods: We conducted a retrospective study in which extension block pinning was done for displaced Mallet finger fractures. We included 10 patients in our study who were treated between 2016 and 2018. Fractures were classified according to Wehbe and Schnieder’s classification. All the procedures were done using ring block anaesthesia. Postoperative radiographic assessment was done at each follow up at 15 days interval. Wires were removed after radiologic confirmation of fracture healing. Assessment of the outcome was done using Crawford’s criteria.Results: According to Wehbe and Schnieder’s classification IIB type was the most common. All fractures involved more than 30% of articular surface. Average operative time was 30 mins. Congruent anatomical reduction was achieved in all the patients (intrarticular step off less than 1 mm). Average healing time of the fractures was 40 days. Seven out of the ten patients had excellent results. No wire related complications were seen in our patients.Conclusions: Extensor block pinning when performed accurately is an easy, economical and effective technique in treatment of mallet fingers

Comparative study between transforaminal epidural selective nerve root block versus interlaminar epidural in the treatment of lumbar radicular leg pain

Background: Sciatic neuralgia is a result of nerve root oedema because of the inflammatory, immunological and mechanical factors. Steroid injections play an important role in the management of sciatic radiculopathy. Steroids act by reducing the oedema around the nerve roots and decreasing pain. Locally administered steroids have the advantage of reduced dosage and targeted delivery around the nerve roots. This forms the basis of epidural steroid injections. This can be given around the nerve root in the transforaminal space or in the interlaminar space. There is a paucity of literature comparing the two techniques of epidural steroid injections. We have done a randomized comparative trial, to compare the effectiveness of the two modalities of injection in the management of a single level unilateral foraminal disc herniation.Methods: Patients were randomized in two groups Group A: Transforaminal epidural (SNRB) and Group B: interlaminar epidural. Same dose of steroid was used in each group.Results: Immediate post injection, 2 week and 1 month transforaminal epidural (SNRB) was better compare to interlaminar epidural however at the end of 3 months the difference was not significant (p=0.08).Conclusions: Both transforaminal and interlaminar epidural injection are effective form of treatment in mild to moderate grade of disc disease. Both the technique provide short lasting relief in the symptoms associated with disc pathology, however pain management is better in transforaminal group compared to interlaminar group. Thus these techniques can be considered for delaying surgery and providing intermitant relief.

Management of boxers fracture with single antegrade bent K-wire

Background: Fractures of the neck of fifth metacarpal are commonly encountered in orthopaedic practice. Management of these fractures is a debatable topic with treatment varying from conservative management to surgical fixation. In our study we used a pre-bent k wire in antegrade fashion to achieve fracture fixation. We found that pre-bent K wire provides an excellent reduction with good correction of neck shaft angle and good restoration of movements at the metcarpo-phalyngeal and inter-phalyngeal joints. Pre-bent K wire provides an efficient and economical modality of fixation in fracture neck of fifth metacarpal fractures.Methods: All patients presenting with fracture neck of fifth metacarpal were managed by pre-bent K wire in antegrade fashion by a single surgeon using a single prebent K wire.Results: All the fractures involved the dominant hand (16 right and 6 left). The mean duration of surgery was 24 mins. Intra operatively the mean no of X ray shoots were 12. At the end of the follow-up there was no significant difference in the TAM in the affected and the unaffected hand. The p=0.17. The mean DASH at the end of the follow up was 2.42. The mean fracture healing time was 45 days.Conclusions: Boxers fracture is very common fracture type in young active adults. Conservative management is usually associated with shorting and angular deformities. Percutenous fixation of the fracture with bent K wire placed in antegrade fashion provides good stability at the fracture site.

Profit efficiency of small-scale farmers participating in USAID markets II in Kano state of Nigeria

The present research determined the profit efficiency of smallholder farmers participating in USAID MARKETS II in Nigeria’s Kano State using undated data collected from 189 farmers drawn through a multi-stage sampling technique. Data elicitations were done through a well-structured questionnaire complemented with interview schedule and both descriptive and inferential statistics were used to analyze the data. The empirical evidence showed an improvement in women folk participation in the program despite strong advocacy of gender stereotype viz. religious and cultural barriers in the studied area. However, this progress owes to the tacit focus of the program on women and youths. Furthermore, it was established that none of the farmer is profit efficient and it majorly owes to extension gap. On the average, a technical unit gained 58.47% of its potential profit, thus lost a profit of N123008 due to inefficient resource mix. Besides, an average farm unit still has the potential to increase his profit efficiency by 41.53%, thus bridging its discrepancy from the frontier surface. Therefore, the study calls on the program promoters to enhance their extension services delivery structure thereby addressing the problem of extension gap that inhibit profit efficiency given its multifaceted influence on risks associated with farmers socio-economic characteristics. Keywords: Profit efficiency, USAID MARKETS II, Small-scale, Rice farmers, Nigeri

Satisfacción laboral y éxito agrícola de procesadores de arroz a pequeña escala beneficiarios de microfinanzas en el estado de Jigawa, Nigeria

Limitation of research information on job satisfaction and enterprise success-remunerative business going concern of rice value chain actors especially the processors has been a challenge to the sustainability of the supportive policy driven rice value chain in the study area. Therefore, this necessitates research so as to identify the possible pitfalls alongside proffer viable scientific remedies that will enhance the sustainability of the entire rice value chain in the study area. Using a cross-sectional data obtained from a total of 133 and 67 par-boilers and millers respectively, through a well-structured questionnaire and interview schedule, the job satisfaction and agripreneurial success of micro-finance benefitted rice processors in Nigeria’s Jigawa state were investigated. Unlike the millers, it was established that majority of the par-boilers were not satisfied with the job and it owes majorly to poor job security and disincentive attitude of the supportive institutions. However, across the study target groups, despite the few hitches, majority of the enterprises were found to be successful and mutually owes to remunerative turnover ratio of the enterprise among others. Nonetheless, vulnerable household’s composition which exacerbates the pressure on the limited resources with negative consequence on the income capital base affected job satisfaction and agripreneurial success of the processors.  Therefore, the study advises the policymakers to strength the macro-economic policies so as to enhance the sustainability of the entire rice value chain in the study area. Also, concerned stakeholders involved in policymaking need to intensify their campaign on the importance of sustainable livelihood by encouraging most of the actors to maintain a fair household size.La escasa investigación sobre la satisfacción laboral y el éxito agroempresarial en la rentabilidad de los actores de la cadena de valor del arroz, especialmente de los procesadores, ha sido un reto para la sostenibilidad de la cadena de valor del arroz, impulsada por políticas de apoyo en la zona de estudio. Por lo tanto, es necesaria una investigación que identifique las posibles dificultades, para ofrecer soluciones científicas viables que mejoren la sostenibilidad de toda la cadena de valor del arroz en la zona estudiada. Utilizando datos transversales obtenidos de un total de 133 trabajadores que escaldan el arroz y 67 piladores, mediante un cuestionario estructurado y un programa de entrevistas, se investigó la satisfacción laboral y el éxito agroempresarial de los procesadores de arroz beneficiados por la microfinanciación en el estado nigeriano de Jigawa. A diferencia de los piladores, se comprobó que la mayoría de los trabajadores que escaldan el arroz no estaban satisfechos con su trabajo, debido sobre todo a la escasa seguridad laboral y a la actitud desincentivadora de las instituciones de apoyo. Sin embargo, en todos los grupos destinatarios del estudio, a pesar de algunos problemas, la mayoría de las empresas tuvieron éxito, lo que se debe, entre otras cosas, al índice de retorno de inversión de la empresa. No obstante, la composición vulnerable de los hogares, que agrava la presión sobre los limitados recursos con consecuencias negativas sobre la base del capital de ingresos, afectó la satisfacción laboral y al éxito agroempresarial de los procesadores de arroz.  Por tanto, el presente estudio aconseja reforzar las políticas macroeconómicas para mejorar la sostenibilidad de toda la cadena de valor del arroz en la zona estudiada. Asimismo, las partes interesadas que intervienen en la formulación de políticas deben intensificar su campaña sobre la importancia de la sostenibilidad de los medios de vida, animando a la mayoría de los agentes a mantener un tamaño de familia adecuado

Statistical and Experimental Study of the Stretching Force for 6061 Aluminum Alloy Using post stretching and pre strecting processes

تم انجاز دراسة عملية و عددية اخذة بالاعتبار تاثير اثنين من المدخلات المتغيرة المهمة (قوة المط وسرعة المط) على سلوك المط لصفيحة المنيوم 6061-0) ) بدلالة نسبه تقليل انخفاض السمك في نوعين من عمليات التشكيل بالمط (تشكيل المط المباشر وتشكيل المط مسبق الشد ) . واجريت التجارب العملية باستخدام قالب على شكل حرف (V) لمط الصفيحة لمستويين مختارين من قوة المط وسرعة المط وفقا الى المصفوفات التصميمية المنجزة أنشات بواسطة تصميم تجريبي لتقنية (D O E) )الاصدار العاشر) . تم انجاز نموذجين باستخدام تقنية طريقة الاستجابة السطحية (R S M) لحالتين من المط (المط المباشر والمط مسبق الشد)، ثم دققت احصائيا لغرض التاكد من مناسبتها باستخدام تحليل التباين (ANOVA)، وظهرت جيدة بنسبة ثقة (95%). وأوضحت هذه النماذج تطابق جيد بين النتائج العملية والنظرية المتوقعة. تم الحصول لكل نموذج معادلة تربيعية تجريبية لأنخفاض نسبه السمك (كاستجابة) بدلالة قوة المط وسرعة المط (كمعاملات ادخال). بينت نتائج النموذج الاول (تشكيل المط المباشر) اشارت الى ان قوة المط فقط تمتلك تاثير اعلى من تأثير سرعة المط على نسبه انخفاض السمك والتي وجد ان لها تأثير ضئيل على هذا النموذج. اما بالنسبه للنموذج الثاني (تشكيل المط مسبق الشد)، بينت النتائج ان كلا قوة وسرعة المط لهما تأثيرعلى نسبة انخفاض السمك، لكن القوة المط لها تاثير اعلى من سرعة المط.An experiment and a statistic study was performed considering the effect of two important input parameters (stretching force and stretching speed) on the stretching behaviour of 6061-0 aluminum sheet in terms of thickness reduction ratio in two types of stretch forming process (post stretching and pre stretching). Experimental tests were carried out using a die with V-shape to stretch the sheet at two selected levels of stretching force and stretching speed and according to the design matrices established by the Design of Experiment (DOE) software (Version 10). Two models with two variable parameters, i.e. stretching force and speed  were built by using the response surface methodology (RSM) technique for the two cases of stretching (post and pre stretching), then checked statistically for adequacy purpose by analysis of variance (ANOVA) analysis, and appeared good with 95 % confidence level. It was found that using the post stretch forming process generally gives a lower thickness reduction ratio than that for pre stretching process. This explains the advantages of using post-stretching process to stretch the 6061-0 aluminum sheet alloy

Comparative study between third and sixth year of medical students regarding basic science in Al-Nahrain College of medicine

Background: The basic sciences have a fundamental role in the development of physicians, there is now an urgent need to facilitate and enhance student retention of basic science knowledge, concepts and principles delivered to the students in the preclinical years .The aim of this research is to :(1) Assess the level of integration of basic medical sciences in the clinical training of medical students.(2) Determine the opinion of medical students about basic medical science. Subjects and Methods: A descriptive Cross sectional study which carried out on one hundred students using consecutive non random sampling technique, there is no inclusion or exclusion criteria. The study was done in Baghdad and conducted during the period from May through July 2012 in Al-Nahrain College of medicine . to determine the integration of the basic medical sciences to the clinical training. Fifty students were participant from third year and the same numbers were from sixth year. The basic medical sciences information was collected by using questions in six main basic medical sciences branches, there were five core multiple choice questions in each branch, the questions were selected from United State Medical License Examination. The study also includes a questionnaire survey which contains ten questions. Statistical analysis :using soft ware MINITAB ,p value bellow 5 representation for significances. Result: this study shows that the percentage of success in passing the test in third year was (54%) in comparison with (34%) in sixth year, the success  rate in pathology was higher in six year in comparison with third year while in other branches was higher in third year. The students’ test score categories in the sixth year reach to (60-69) while in third year was up to (80-89). The opinion of students’ about integration of the basic medical sciences was (46%) for good in the third year while the sixth year choose (56%) for average, the third year choose (40%) for enough for the bulk of information in comparison with (46%) for overcrowded in sixth year. The two groups was agreed in chosen the same opinion in method of teaching was accepted, and for the interest it was limited, this results supported with a lot of international studies. Conclusions: this study concluded on the important of integration and change teaching method are one of the tool which can help to reach the target  . Key word; basic medical science  ,third year ,sixth year ,integratio

Strength Properties of Polymer Reactive Powder Concrete with Waste Materials

Reactive powder concrete, or RPC, outperforms conventional or even high-performance concrete in terms of ultra-high strength and better durability. Several buildings were destroyed in Iraq, and recycling the garbage from these buildings can significantly help reduce waste and environmental pollution as well as serve as a source of aggregate for use in new construction. Reusing garbage and using sustainable building materials are now crucial environmental challenges, so this study aimed to replace the natural fine aggregate, NFA, used in preparations of polymer reactive powder concreter, "PRPC" with recycled aggregates, or RA, from crushed old concrete, COC, in order to make PRPC production more environmentally and sustainably friendly. In this study, RPC is modified by adding styrene butadiene rubber (SBR), a polymer, to the original mixture at a ratio of 13% by weight of cement. This study sought to determine the effect of using COC as recycled fine aggregate (RFA) on the compressive, splitting, and flexural strengths of PRPC. The main objective of this investigation is to study the effect of oil (water, new oil, and waste engine oil) on the compressive and tensile strengths of PRPC with COC and to compare the behavior with that of a control mix (PRPC with NFA). The mixtures were prepared using six different percentages of RFA, replacing 0, 20, 40, 60, 80, and 100% NfA. After 28 days, the six mixes were divided into three groups. The first was still being cured in water, W; the second in waste engine oil, WEO; and the third in kerosene oil, KO. The results showed that using COC as RFA in PRPC was viable, and according to this investigation, the mix with 40% COC replacement with NFA provides the highest values of compressive strength, tensile strength, and flexural strength before and after exposure to liquids (water, new oil, and waste engine oil). Doi: 10.28991/CEJ-2023-09-08-09 Full Text: PD