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Optical absorbance chemosensor based on digital lock-in Amplifier for the low limit real-time detection of Ethylamine as a volatile organic compound
(Chuka University, 2025) Doreen Chepkorir
Volatile organic compounds (VOCs), frequently released from industrial processes and domestic products, pose serious threats to both environmental quality and human health. Continuous real-time monitoring of VOCs in air and water is therefore critical for environmental protection and occupational safety. Conventional methods such as electrochemical sensors and gas chromatography are limited by high cost, complexity, and slow response, while colorimetric chemosensors often suffer from poor reliability due to high signal-to-noise ratios. This presents a straightforward, affordable, and extremely sensitive technique for real-time monitoring of VOCs, concentrating on the ethylamine (Et-NH ) as a pollutant. The primary goal of this research was to design, build, and test an optical absorbance chemosensor using a digital lock-in amplifier for signal processing and isoindoline dye (ID1) as the sensitizer. In particular, the study aimed to performed detailed characterizations of the LEDs and the dye to understand its optical properties including absorption spectra and response to Et-NH2(aq), to design and build a sensor circuits suitable for real time monitoring of VOCs, to test the functionality of the sensor based on a digital lock-in amplifier for low limit real time detection of Et-NH2(aq) under laboratory conditions and to compare the obtained results using the fabricated sensor with commercially available sensors. The sensor was constructed by building an AC+DC adder circuit integrated with a photodiode and an infrared LED tuned to the dye’s responsive absorption band. The LED light, modulated by the digital lock-in amplifier, excited the dye film and the transmitted intensity was recorded and analyzed. Calibration was achieved by titrating solution of Et-NH into a sampling cuvette, while an oscilloscope was employed to monitor signal characteristics. The results in the developed system demonstrated strong sensitivity to aqueous Et-NH , with a limit of detection (LoD) of 2.35 μM which is far below the aquatic toxicity threshold of 2.22 mM. This presents high sensitivity to Et-NH , rapid response, excellent selectivity against interfering species and stable performance. In conclusion, the developed optical absorbance chemosensor offers a reliable, low-cost, and real-time method for detecting VOCs in aqueous environments without the need for phase membranes. It is recommended that further optimization be conducted to extend the applicability of the sensor to a broader range of VOCs and to integrate the sensor into portable devices for on-site environmental monitoring.
Stakeholders and resource preparedness for the implementation of competency-based education in public junior schools in Imenti south sub county, Meru county, Kenya
(Chuka University, 2025) Nteere, Mercy Nkirote
The education sector is undergoing a global transformation with the adoption of Competency-Based Education (CBE), which emphasizes practical skills over traditional content memorization. Kenya's implementation of CBE since 2017 is a major shift in its education system, aiming to equip learners with 21st-century skills for arapidlychangingworld. ImplementationofCBErequiresreadinessintermsofteacher preparedness, availability of infrastructure, parental involvement, and adequate instructional materials. The study, grounded in Systems Theory was guided by the following objectives:to establish the relationship between teachers' preparedness and implementation of CBE in Junior schools, to establish the relationship between infrastructural resources preparedness and CBE implementation in Junior schools, to establish the relationship between parents’ preparedness and CBE implementation in Junior schools and to access the relationship between junior school instructional materials preparedness and CBE implementation. Thestudy adopted a descriptive survey research design. Data was collected through structured questionnaires and interviewschedules.Asamplesizeof279respondents,derivedfromatargetpopulation of 932 using the Yamane formula, included 119 teachers, 40Deputy Head teachers and 119 parents were selected through proportionate stratified sampling and 1 Sub-County director of education was selected purposively. Pilot study was conducted to evaluate the quality of the study instruments.Reliability was assessed using Cronbach’s alpha achieving a value of 0.8, while validity was ensured through expert reviews for face and content validity. Data was analyzed using both descriptive and inferential statistics usingtheSPSS version26 softwareforstatistical computing.The findings revealedthat teachers were moderately prepared to implement CBE. Although many had undergone some training, few had received comprehensive preparation and there was a strong demand for continuous professional development and mentorship. Infrastructural resources in schools were found to be inadequate, with limited classrooms, laboratories and ICT facilities hindering practical learning experiences. Parental preparedness was also found to be low, with many parents lacking sufficient understanding of the curriculum and demonstrating limited engagement in supporting school activities. Instructional materials were not adequately available, with shortages of textbooks, teacher guides, and digital learning tools being common, and delays in distribution further constraining implementation. The study concluded that these gaps in teacher training, infrastructure, parental involvement, and instructional materials continue to undermine effective CBE implementation. It recommended, enhancing teacher professional development, improvinginfrastructural investment, strengtheningparental sensitization, ensuring timely supply of instructional resources and fostering collaborative partnerships among schools, government and communities. The findings provide valuable insights for policymakers, curriculum developers and school administrators seeking to strengthen the implementation of CBE in Kenya.
A History of The Presbyterian Church Of East Africa in The Eastern Region (1915 To 2022)
(Journal of Humanities and Social Sciences, 2024-11-16) Lucy Muthoni Mwindi; Dickson Nkonge Kagema; Caroline Mucece Kithinji
The study sought to determine the impact of the Presbyterian Church of
East Africa in the Eastern Region from 1915 to 2022. PCEA was introduced in
the Eastern Region by the Church of Scotland Mission (CSM) in 1915. The
Eastern Region was the third mission area after Kikuyu and Tumutumu. Their
mission strategy was holistic in nature, combining evangelism, education,
medical and industrial work. Since its inception, PCEA has been involved in
transforming the socio-political and economic lives of people in the Eastern
Region. There is a paucity of scholarly work on the impact of other
missionaries like the Methodists, the Roman Catholics and the Anglicans in
Meru, but that of PCEA is conspicuously missing. Thus, there is a need for
this kind of study. Data was collected by descriptive survey research design.
Data was collected and analysed from 376 church members, 53 church
ministers and 9 presbytery moderators. The study established that PCEA has
had both negative and positive impacts on the transformation of the people
in the Eastern Region. The study recommends that PCEA should improve on
the management and supervision of its institutions to ensure they serve the
purpose for which they were established.
Impact of supply chain quality assurance on performance of Kenyan education ministry state agencies: An empirical analysis
(Journal of Sustainable Development of Transport and Logistics, 2024-11-15) Jeremiah Kiio Nthusi; Noor Ismail; Miriam Thogori; Charles K. Ndeto
Purpose: This study examines the effect of supply
chain quality assurance on the performance of state agencies
under Kenya's Ministry of Education. Methodology: A
descriptive-correlational research design was employed. Data
was collected through questionnaires from a sample of 212 staff
members across 8 state agencies, selected using stratified
purposive sampling. Both descriptive and inferential statistics
were used for analysis. Results: The findings revealed that state
agencies did not effectively embrace supply chain quality
assurance practices. A strong positive correlation was found
between supply chain quality assurance and agency
performance. The ineffective implementation of quality
assurance was identified as a critical factor in the declining
performance of these agencies. Theoretical contribution: This
study contributes to the literature on supply chain quality
management in the public sector, particularly in developing
countries. It provides empirical evidence supporting the
Expectation Confirmation Theory in the context of educational
institutions. Practical implications: The study recommends that
state
agencies in Kenya's education sector prioritize
implementing supply chain quality assurance practices,
including ISO certification and staff training, to improve their
overall performance and service delivery.
Causes Of Environmental Degradation In Chuka Igambang`Ombe Sub-County, Kenya
(Journal of Environmental Sciences and Technology, 2024-09-14) Sarah Kagendo Gitonga; Dickson Nkonge Kagema(; Jonathan Kathenge
This study investigated the causes of environmental degradation in Chuka
Igambang’ombe Sub-County, Tharaka Nithi County, Kenya. Environmental
degradation, characterised by deforestation, pollution, and soil erosion,
poses significant threats to ecosystems and human well-being.
Environmental challenges persist despite the Catholic Church's active
participation in conservation efforts such as tree planting, river
rehabilitation, soil conservation, and awareness campaigns. Identifying the
underlying factors is crucial for developing effective interventions. The
study employed a descriptive survey design targeting a population of
15,574 Church members. A sample size of 389 participants was selected,
including ten priests, ten development committee members, 86 youths, 98
members of the Catholic Men Association (CMA), and 175 members of the
Catholic Women Association (CWA). Data was collected through interviews
and questionnaires and analysed using descriptive statistics. The findings
revealed that deforestation, pollution, improper waste disposal,
overgrazing, lack of environmental knowledge, and encroachment on
natural habitats were crucial factors contributing to environmental
degradation in the region. The study concludes that these factors and
inadequate management strategies exacerbate degradation. It is
recommended that the government and stakeholders enforce stricter
regulations against deforestation, promote environmental education, and
enhance waste management practices to mitigate these effects.