An effective electrical isolation scheme by iron implantation at different substrate temperatures

High-energy implantation of iron in n-type doped InP epilayers at different substrate temperatures: 77K, room temperature (RT), 100degreesC and 200degreesC was investigated to study the electrical isolation of n-type InP. Iron isolation implants were performed at 1MeV with a fluence of 5 x 10(14) /cm(2). This isolation scheme was chosen to place most of the iron atoms well inside the n-type doped layer. The sheet resistivity (R,), sheet carrier concentration (n(S)) and sheet mobility (p) were measured as a function of substrate temperature and post-implantation annealing temperature (100 - 800degreesC). Samples implanted at 77K, RT and 100degreesC show more or less the same trend of postimplant annealing characteristics. A maximum sheet resistivity of similar to1 x 10(7) Omega/rectangle was achieved for samples implanted at 77K, RT and 100degreesC after annealing at 400degreesC. A lower resistivity of similar to1 x 10(6) Omega/rectangle was obtained for a 200degreesC implant after annealing at 4000C. Lower damage accumulation due to enhanced dynamic annealing is observed for the highest implantation temperature. For 200degreesC substrate temperature, annealing above 4000C resulted in a gradual decrease in sheet resistivity to a value close to that of the starting material. But this is not the case for the lower substrate temperatures. The sheet resistivity was increased again for 77K, RT and 100()C implant after annealing at 600degreesC. We infer that for 77K, RT and 100degreesC implantation temperatures, the electrical isolation is due to a product of both damage related centers and defects related to the presence of Fe whereas for 200degreesC substrate temperature, we infer that only damage induced compensation removes the carriers. These results show the importance of iron implants as a device isolation scheme.</p

Operational Research Project Management, Experiences, Challenges and Lessons Learnt

Introduction: Effective project management revolves around Strategic Management. Logistics seem simple and straight forward but, often the role&nbsp; it plays in scientific undertakings is overlooked. It is usually assumed that research starts and ends in the laboratory. It is a fact that, for research activities to be successful, it requires exceptional planning to ensure that, resources are available as per the approved work-plan. This entails&nbsp; determination of what, when, who, why and how it is to be done. Recent studies indicate that, logistics-related activities' impact on research&nbsp; undertakings significantly. Objective: To document the project management experiences and lessons learnt in coordinating and implementation of East Africa Public Health Laboratories Networking Project –Operational Research (EAPHLNP-OR) activities in five East African countries, namely: Kenya, Rwanda, Burundi, Uganda and Tanzania. Methodology: The operational research component of the EAPHLNP, KEMRI established an OR Secretariat to coordinate the project activities in&nbsp; Kenya and provide leadership to regional principal investigators. In consultation with the project Secretariat, the role of the administrator involved Work plan and budget preparation, planning, organizing, communicating, coordinating local and regional meetings, linking KEMRI research team with the study site (Hospital Administration) and Research Teams in the various counties. The site Teams obtained informed consent, recruited respondents, collected specimens, analyzed the specimens and shipped a portion of the same together with the results to KEMRI. Key Activities Of The Project: Managing financial aspects (budget and financial report preparations), logistical coordination, and procurement of training materials, organizing for meeting venues, taking minutes, travel arrangements and participation in scientific report writing. Control mechanism such as dairies, ledger books, work plan charts and schedules, managing and monitoring the progress of the project activities. Lesson Learnt &amp; Challenges: Interpersonal skills were essential at all stages of the project. The critical stage was the forming, storming, and&nbsp; norming stages. Here, group dynamics and conflicts took center stage. This threatened to stall the OR Project. Timely and constant communication with the study site coordinators, prioritization of scheduled project activities, was essential. Ensuring all parties are kept informed on the progress of the OR activities. The information in user-friendly format dairies and schedules provided the necessary feedback at administrative level, on project performance and at research findings. Key challenges included fluctuating funding, group dynamic conflicts and staff transfers. Discussion: EAPHLNP-OR was a Seven (7) years project undertaking, which for effective management involved understanding of the operating environment, strategic planning for short and long term goals, constant communication, review of priorities, documentation and practise of goodinterpersonal skills. Conclusion: Successful project management in OR required an administrator to coordinate the utilization of the available resources both capital and human. This is the second supplement in this issue only aspects on findings from TB and Enteric studies done in Kenya have been addressed.Three regional policy briefs on TB Enteric and malaria have been included

The distribution of toxic metals in the human retina and optic nerve head: Implications for age-related macular degeneration.

OBJECTIVE:Toxic metals are suspected to play a role in the pathogenesis of age-related macular degeneration. However, difficulties in detecting the presence of multiple toxic metals within the intact human retina, and in separating primary metal toxicity from the secondary uptake of metals in damaged tissue, have hindered progress in this field. We therefore looked for the presence of several toxic metals in the posterior segment of normal adult eyes using elemental bioimaging. METHODS:Paraffin sections of the posterior segment of the eye from seven tissue donors (age range 54-74 years) to an eye bank were examined for toxic metals in situ using laser ablation-inductively coupled plasma-mass spectrometry, a technique that detects multiple elements in tissues, as well as the histochemical technique of autometallography that demonstrates inorganic mercury, silver, and bismuth. No donor had a visual impairment, and no significant retinal abnormalities were seen on post mortem fundoscopy and histology. RESULTS:Metals found by laser ablation-inductively coupled plasma-mass spectrometry in the retinal pigment epithelium and choriocapillaris were lead (n = 7), nickel (n = 7), iron (n = 7), cadmium (n = 6), mercury (n = 6), bismuth (n = 5), aluminium (n = 3), and silver (n = 1). In the neural retina, mercury was present in six samples, and iron in one. Metals detected in the optic nerve head were iron (N = 7), mercury (N = 7), nickel (N = 4), and aluminium (N = 1). No gold or chromium was seen. Autometallography demonstrated probable inorganic mercury in the retinal pigment epithelium of one donor. CONCLUSION:Several toxic metals are taken up by the human retina and optic nerve head. Injury to the retinal pigment epithelium from toxic metals could damage the neuroprotective functions of the retinal pigment epithelium and allow toxic metals to enter the outer neural retina. These findings support the hypothesis that accumulations of toxic metals in the retina could contribute to the pathogenesis of age-related macular degeneration

A Detail Study of Wavelet Families for EMG Pattern Recognition

Wavelet transform (WT) has recently drawn the attention of the researchers due to its potential in electromyography (EMG) recognition system. However, the optimal mother wavelet selection remains a challenge to the application of WT in EMG signal processing. This paper presents a detail study for different mother wavelet function in discrete wavelet transform (DWT) and continuous wavelet transform (CWT). Additionally, the performance of different mother wavelet in DWT and CWT at different decomposition level and scale are also investigated. The mean absolute value (MAV) and wavelength (WL) features are extracted from each CWT and reconstructed DWT wavelet coefficient. A popular machine learning method, support vector machine (SVM) is employed to classify the different types of hand movements. The results showed that the most suitable mother wavelet in CWT are Mexican hat and Symlet 6 at scale 16 and 32, respectively. On the other hand, Symlet 4 and Daubechies 4 at the second decomposition level are found to be the optimal wavelet in DWT. From the analysis, we deduced that Symlet 4 at the second decomposition level in DWT is the most suitable mother wavelet for accurate classification of EMG signals of different hand movements.

Nutritional status of adult male on art at Kericho District Hospital, Kericho County, Kenya

Background: Nutrition and HIV are strongly related and any immune impairment as a result of HIV leads to malnutrition while malnutrition leads to immune impairment and thus worsens the effect of HIV. Individuals living with HIV have special nutritional needs irrespective of whether they are on anti-retroviral treatment or receiving care services.Objective: To establish nutritional status of adult male on ART at Kericho District Hospital, Kenya.Design: Cross sectional analytical study.Setting: HIV clinic at Kericho District Hospital, Kenya.Subjects: HIV positive adult male patientsResults: Body Mass Index ≥18.5 and ≤ 24.5 (70.92), &gt;16 &amp; &lt; 18.5 (11.94), &gt;25.5 and &lt; 30 (11.94), ≤ 16 (2.58) and ≥30.Conclusion: There is a high burden of malnutrition among PLHIV on ART (29.1%). Nutritional assessment, Counseling and support (NACS) should be the key intervention during the course of chronic HIV care and follow up

Facile synthesis of reduced graphene oxide/MWNTs nanocomposite supercapacitor materials tested as electrophoretically deposited films on glassy carbon electrodes

This paper reports on a facile synthesis method for reduced graphene oxide (rGO)/multi-walled carbon nanotubes (MWNTs) nanocomposites. The initial step involves the use of graphene oxide to disperse the MWNTs, with subsequent reduction of the resultant graphene oxide/MWNTs composites using l-ascorbic acid (LAA) as a mild reductant. Reduction by LAA preserves the interaction between the rGO sheets and MWNTs. The dispersion-containing rGO/MWNTs composites was characterized and electrophoretically deposited anodically onto glassy carbon electrodes to form high surface area films for capacitance testing. Pseudo capacitance peaks were observed in the rGO/MWNTs composite electrodes, resulting in superior performance with capacitance values up to 134.3 F g−1 recorded. This capacitance value is higher than those observed for LAA-reduced GO (LAA-rGO) (63.5 F g−1), electrochemically reduced GO (EC-rGO) (27.6 F g−1), or electrochemically reduced GO/MWNTs (EC-rGO/MWNTs) (98.4 F g−1)-based electrodes.© 2013, Springer Science+Business Media Dordrecht

Experience and Lessons Learnt on Health Care Personnel Participating In the Implementation of TB Operational Research at (EAPHLNP -OR) Malindi, Kenya

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Resistance of Common Circulating Enteric Bacterial Pathogens to Prescribed Antibiotics Among Under Five Years in Selected Public Hospitals in Kenya

No Abstract