Physical sciences

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Sensitive sensor for real time monitoring of hydrogen sulfide (H2S) as a water pollutant
(Chuka University, 2024) Riungu Jim Kimathi
Water is a finite and a vital resource. Monitoring its pollution is therefore vital in the prevention of the negative impacts that it can have on the environment and human health. Through water pollution, hydrogen sulfide (H2S) is fed into water. Recycling of waste water necessitates efficient and real time sensing of the presence of hydrogen sulfide. Even though significant effort of sensing hydrogen sulfide in water has been made, the sensors and mechanisms used are limited in level of detection, not portable, do not detect in real time, lack well-trained personnel to handle them and are highly expensive. In addition, they require complex instrumentation and have possibilities of introducing additional contamination in water. Therefore, this study designed a real time, highly sensitive, effective, cheap and portable sensor based on dye absorption, squarylium dyes (SQ1) and modern lock-in amplifier, to sense the presence and concentration of hydrogen sulfide (H2S) in water. A Light Emitting Diode CHANZON (LED) with emission wavelength of 650-660 nm was coated with SQ1 dye to act as a sensing region. Its warm up in air and in the analyte was found to be 25 minutes and 20 minutes respectively, which was accounted for in data collection. 1.647 M H2S was diluted accordingly, to yield two stock solutions, 1 and 2 with concentration 100 μM and 5 μM respectively. The voltage response Vout from the lock-in amplifier was read against time at different concentration of H2S and a graph of Vout (mV) against time (minutes) was plotted and used to provide changes in Vout when different aliquots were added. The limit of detection (LoD) was found to be 25 nM. This LoD is 60 times lower than the potability of H2Saq which is 1.5 µM. Because of the high sensitivity and low LoD (25 nM) of the developed sensor, this study concludes that the sensor can be used for real-time monitoring of presence and concentration of H2S in water. This will in turn help in water recycling and also ensure consumption of clean water free of H2S, which is hazardous to human health.
Geo-electrical resistivity investigation of iron ore mineral deposits in Mbeu area, Meru county, Kenya
(Chuka University, 2024) Kinyua Jasper Mujumbe
Global demand for iron or its products has risen over the years due to the growing housing, road, and railway industry and the manufacture of machinery. Studies leading to the location of more iron ore fields need to be performed in order to determine the suitability of available iron ore as a raw material for iron production. Earlier, studies carried out within Mbeu and Kimaachia areas in Meru County, Kenya, using gravity and magnetic Geophysical methods did not pick shallow deposits and discontinuous magnetite mineralization occurring in rocks and veinlets. This was attributed to relatively low density contrast and magnetic susceptibility on shallow deposits and unevenly distributed magnetite rich rocks. This, therefore, necessitated the need to integrate an electrical resistivity geophysical method that can detect isolated electrical conductors in the subsurface. This research involves the use of electrical resistivity along the areas identified around 00 06’ 24’’N and 370 50’ 49’’E. By taking measurements on the ground surface, the electrical resistivity method calculates the true resistivity of the subsurface. The potential difference that results from injecting current into the earth is measured at the surface. The ground resistivity measurements were performed by the use of the LS 2 ABEM terrameter. RES2DINV software was employed in the quantitative interpretation of the data by generating models of apparent resistivity pseudo-sections. The software carried out a least square inversion on the measured apparent resistivities and induced that the true resistivity of alluvium, rocks, and clay saturated with water ranges from 2.21 Ωm to 487 Ωm, 212 Ωm to 3000 Ωm and 2.21 Ωm to 65 Ωm respectively. A comparison between electrical resistivity levels and chargeability factors guided a quantitative characterization of the subsurface. The characterization established that the subsurface ore distribution is divided into two portions: alluvium and rocks enriched with iron ore and alluvium and rocks containing disseminated deposits of iron ore. The regions of the model identified by resistivity and chargeability values of 17.4 Ωm to 406 Ωm, 208 Ωm to 886 Ωm and 0.01 msec to 3 msec, 0.091 msec to 4.64 msec are inferred as alluvium and rocks enriched with iron ore deposits, respectively; the other regions characterized by resistivity and chargeability of 110 Ωm to 487 Ωm, 542 Ωm to 995 Ωm and 3.326 msec to 7.87 msec, 4 msec to 7.07 msec are of alluvium and rocks containing disseminated deposits of iron ore, respectively. This study has established that Mbeu iron deposits are an extensive resource occurring at deep and shallow depths in the form of grained magnetite mixed with alluvium and rocks containing magnetite. It has also been found that magnetite is the main ore in the geological formations. The ore-bearing rocks and alluvium appear at an approximate depth of 1.25 m to 65.6 m in most of the profiles and extend deep beyond the terra-meter probe depth. These results on the presence of iron ore deposits will be essential to society in that mining and extraction of mineral ores will provide employment opportunities to the locals. Taxes and royalties generated will contribute to the economic growth of the region and country.
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.
FIRST PRINCIPLES STUDY ON EFFECTS OF PRESSURE AND NIOBIUM DOPING ON STRUCTURAL AND ELECTRONIC PROPERTIES OF MOLYBDENUM DISULFIDE MONOLAYER
(Chuka University, 2023-10) MUTAVA GABRIEL MUTINDA
Semiconductor materials are dominant in the fabrication of electronic devices. Unlike metals, the presence of an energy band gap makes them ideal for application in optoelectronics nanostructures. Silicon was the most preferred 2D material to be used, but due to its limitations, for example, quantum tunneling effects, graphene was preferred to silicon. However, graphene has no bandgap, and since the bandgap property is very useful in electronics, research is ongoing to replace silicon and graphene with Transition Metal Dichalcogenides (TMDs). TMDs make nanostructures easily with adjustable energy bandgap, hence applicable in optoelectronics. They exhibit various unique optoelectronic characteristics, attracting interest due to distinct features from bulk predecessors and have bandgap characteristics between 1.80 - 2.30 eV, which can be tuned to fabricate Field Effect Transistors (FET) and other optoelectronic devices. Molybdenum disulfide has sparked attention among TMDs because of the potential of tuning the band gap. Up to date, research on the effects of impurities and pressure on the energy band gap of molybdenum disulfide have been studied, resulting in energy band gaps falling between 1.3 - 1.55 eV. There is need to reduce the value of the energy band gap further so as to make the semiconductor applicable at lower energies. Therefore, this study combined the ionic doping and pressure application on MoS2 in an attempt to narrow the energy band gap to a lower value that could accommodate majority of radiations falling under electromagnetic spectrum. Structural optimization of MoS2 monolayer and niobium doped MoS2 was done using the Density Functional Theory (DFT) method as implemented by the Quantum ESPRESSO simulation package. The study utilized PBE-GGA method of approximation and the number of k-points utilized were 8 x 8 x 1. The structure was optimized to a cell dimension of 3.175 Å for 𝑎 = 𝑏 parameters. A vacuum height of 14.971 Å served to minimize artificial interactions between periodic layers. A 4 x 4 x 1 supercell was modelled and had optimized dimensions of 12.57 Å for 𝑎 = 𝑏 and a vacuum height of 14.971 Å. Its band gap energy was found to be 1.70 eV. Upon 8.33% niobium doping of the 4 x 4 x 1 MoS2 supercell, the energy band gap reduced to 1.375 eV. A pressure in the range of −2.852 GPa to 6.832 GPa was applied, which corresponds to strains ranging from 2. 52 % to -2.50 %. The energy band gap for undoped MoS2 monolayer reduced from 1.70 eV to 1.40 eV at a pressure of -2.852 GPa. The energy band gap for the 8.33% Nb doped MoS2 monolayer narrowed from 1.375 eV to 1.25 eV at a pressure of -5.166 GPa. The combined effect decreased the band gap of MoS2 monolayer from 1.70 eV to 1.25 eV. This study concludes that the combined effect of Nb doping and pressure on the structure of molybdenum disulfide can improve its electronic properties by reducing its energy band gap. This property makes it useful in fabricating optoelectronic devices which can work well at lower energies.
AB INITIO STUDY OF STRUCTURAL AND PIEZOELECTRIC PROPERTIES OF HAFNIUM DOPED BISMUTH SODIUM POTASSIUM TITANATE
(Chuka University, 2023-10) MWANZIA BONFACE MUTUKU
Piezoelectric materials have gained increased attention in the recent times due to their significant technological applications. These materials are widely used to make ultrasound transducers, sensors, actuators and others are used for energy harvesting. Due to its brilliant piezoelectric properties, Lead Zirconate Titanate (PZT) is mostly used with a piezoelectric constant of 𝑑33 = 374 𝑝𝐶/𝑁 from experimental reports and 306 − 314 𝑝𝐶/𝑁 from theoretical studies. However, due to the toxic nature of lead oxide which is formed when PZT is being manufactured, there is increased effort in development of lead-free materials. Several classes of materials have recently been studied and are now being considered as potential alternatives to PZT. Lead free perovskite systems such as Bismuth Sodium Potassium Titanate (BNKT) have been developed, with a piezoelectric constant 𝑑33 = 157 𝑝𝐶/𝑁 . However, the main drawback of this system is that it is highly corrosive and has a low piezoelectric constant compared to PZT. In the quest to provide suitable alternatives, dopants such as zirconium have been used, which improved the piezoelectric constant of BNKT up to203 𝑝𝐶/𝑁. Hf which possesses similar physico-chemical properties as zirconium has led to an improvement in the piezo electric constant of other piezoelectric systems such as in hafnium doped Barium Titanate (BT). It has an added advantage of being extremely resistant to corrosion, which is expected to mitigate the corrosive nature of BNKT. In this study, hafnium has been incorporated in BNKT so as to engineer an alternative material suitable for piezoelectric applications. Density Functional Theory (DFT) method was used to predict the structural and piezoelectric properties of hafnium doped BNKT, starting with those of Bismuth Sodium Titanate (BNT) and BNKT. The exchange and correlation was taken as the Generalized Gradient Approximation (GGA). The optimal lattice parameters for BNT were found to be 𝑎 = 5.57 Å and 𝑐/𝑎 ratio of 2.50 for the conventional cell, having space group R3c space group number 161. Piezoelectric constant for this system was found to be 97.67 pC/N. This structure was adopted for doping and further calculations. Potassium doped bismuth sodium titanate was modelled using VESTA software and its optimized lattice parameter was found to be 𝑎 = 5.60 Å. Piezoelectric constant for this system was found to be 147.42 pC/N. Hafnium doped BNKT had an improved piezoelectric constant of 205.52 pC/N for 3% hafnium doping, which decreased to 163.22 pC/N at the level of 6% doping. The results shows that small amounts of hafnium improved the piezoelectric constant of BNKT from 147.42 pC/N to 205.52 pC/N. Elastic and elastic compliance full tensors for these systems was also generated with elastic constants of C33 = 286.48 Gpa, 282.13 Gpa, 257.193 Gpa and 276.43 Gpa for BNT, BNKT, 3% Hf doped BNKT and 6% Hf doped BNKT respectively. This study concludes that doping BNKT with hafnium indeed improves the piezoelectric properties of BNKT. This makes this material more useful in energy generation since high piezoelectric constant leads to efficient mechanical – electrical energy conversion in the piezoelectric materials.
ANALYSIS OF PRODUCTION, SOCIO-ECONOMIC AND INSTITUTIONAL FACTORS AFFECTING TECHNICAL EFFICIENCY OF SMALLHOLDER BANANA PRODUCERS IN KIRINYAGA CENTRAL SUB-COUNTY, KENYA
(Chuka University, 2023-10) MATIVA JACKSON MKENYE
Banana provides food, nutrition security and income for most households and is fourth most popular food crop in the world after wheat, maize and rice. Despite its significance, full potential of banana production in Kenya remains unexploited by smallholder producers. This is as a result of low technical efficiency especially in utilization of farming inputs and producer specific factors like production, socio-economic and institutional factors among others. In Kirinyaga County, the actual banana production is at 4-18 tonnes per acre against the potential of 30-40 tonnes. Due to the limited supply of resources for production, attainment of highest possible levels of technical efficiency is key to achieving sufficiency in banana farming. This study aimed at analyzing the effects of production, socio-economic and institutional factors on technical efficiency of smallholder banana producers in Kirinyaga Central Sub-County, Kenya. The study used a cross-sectional research design and targeted a population of 24,440 smallholder banana producers. Multistage sampling technique was employed where purposive sampling and simple random sampling methods were used in some stages to sample respondents in the study area. A sample of 402 smallholder banana producers were selected. Using a questionnaire, primary data on production, socio-economic and institutional factors affecting technical efficiency of banana production was collected. The data was then analyzed using Stata version 17 and SPSS version 25. Descriptive statistics were used to describe the production, socio-economic and institutional factors of the smallholder banana producers. A stochastic frontier analysis approach was used to model the technical efficiency level using the Cobb-Douglas function. The stochastic production function of the Cobb Douglas function was estimated using the maximum likelihood estimation technique. The study showed that the level of banana production technical efficiency among the smallholder producers varied between 0.9% to 95.5% and average technical efficiency of 83.1%. According to the model parameters calculated, land set aside for production of banana, banana suckers and agrochemicals were significant production factors in banana cultivation at 5% significance level. The study found that agrochemicals and planting materials had positive effects on technical efficiency whereas land size had a negative impact on technical efficiency. This implied that increasing the amount of land set aside for banana production by an acre reduces the amount of banana harvested by 0.438 kgs while increasing the amount of planting materials and agrochemicals used by one unit increases banana production by 1.315 and 0.155 kgs, respectively. The study found that decision makers’ age and size of the household had negative effects on banana production technical efficiency whereas education, experience, producer group membership and market access had positive effects. The study recommends people with high levels of education to venture into banana production. In addition, producer group formation and membership be encouraged for the benefit of increasing technical efficiencies. The inefficient producers are advised to increase their present output by enhancing technical efficiency as a result of the inefficient utilization of their resources throughout production.
IMPACTS OF SHORELINE CHANGE ON THE NEARSHORE MARINE ENVIRONMENT AT GAZI BAY, KENYA; BETWEEN 1989 AND 2020
(Chuka University, 2023-10) MWANGI PAULINE NYAMBURA
Coastal zones are dynamic environments influenced by both human and natural processes. In the current study, the objectives were to estimate change in shoreline at Gazi bay between 1989 and 2020, to identify the spatial-temporal changes of the nearshore marine environment; particularly on mangrove forests and to establish hotspot areas of shoreline change. The study applied both longitudinal and ecological research design. Digital Shoreline Analysis System (DSAS 5.0), a software within ArcGIS Platform computed change statistics along the study area over the study period. Kalman filter model was used to project future shoreline positions. Supervised, and unsupervised classification methods were used in detecting vegetational change. The relationship between shoreline change and mangrove cover change was examined using the Pearson Correlation coefficient. The average End Point Rate (EPR) of shoreline change at Gazi bay was estimated at -1.38 m/y, with the northerner sections of the western creek showing an accretion rate of 2.38 m/y. At least 88.62 hectares of the mangroves had been affected by the sedimentation processes, representing 55% of mangroves in the study site. A hotspot area exhibiting a change of -4.99m/y was observed at the opening of the Mkurumudzi River, where sandspits and sandbars had formed. Other hotspots areas were at the site with introduced artificial rocks to serve as gabions, fish landing sites, and at the northern side of western creek that had enhanced sediment accretions killing mangroves. A negative correlation between shoreline change and mangrove cover loss was observed, though not statistically significant (r=-0.536, p=0.273, α=0.05). Assessing the dynamics and vulnerabilities of the coastal zones is very crucial in understanding sustainable coastal development and management. These findings provide valuable insights on shoreline changes that could contribute towards integrated coastal zone management strategies for the area.
STRUCTURAL, OPTICAL, AND SURFACE POTENTIAL CHARACTERIZATION OF NICKEL, ZINC DOPED MAGNESIUM FERRITES SYNTHESIZED USING SOL-GEL AUTO-COMBUSTION METHOD
(Chuka University, 2022-09) ALEX, NJOROGE
Nano-sized spinel ferrites have attracted heightened scientific focus due to their interesting structural, morphological, magnetic, optical, and electrical properties. Metal substitution in the structural equation of the spinel ferrite (MFe2O4) plays important roles in the modification of its physical properties in order to suits specific applications, like gas sensing. Recently, air pollution has greatly increased, e.g., leakage of liquid petroleum gas (LPG). This lead to deaths, fire outbreaks and other health complication. As a result, there is demand for effective gas sensors with lower limits of detection. Sensing material especially the ferrites are limited in their sensitivity and operate at high temperatures. Among the ferrites, Mg-Zn ferrites are most important magnetic oxide due to their properties. Substitution of any magnetic ion by replacing Zn2+ in Mg-Zn ferrite plays an important role in modifying its properties and hence enhancing its sensing properties. This work, aimed at contributing to the effort focused to improve ferrite sensing properties and overcome these limitations by ternary ionic substitution. Consequently, NixZn0.5-xMg0.5Fe2O4 (x = 0, 0.1, 0.3 and 0.5) ferrite nanoparticles were synthesized by Citra gel auto-combustion method at a pH 7 and characterized for their structural, elemental composition, electronic and optical properties. Pre-elemental analysis by x-ray fluorescence revealed the expected stoichiometry of the synthesized nanoferrites with low amount of impurities. X-ray Diffraction analysis confirmed cubic spinel nature of the samples with crystalline size between 26.90-43.34 nm using Debye Scherrer equation, 8.94 – 26.38 nm using Modified Debye Scherrer plots and 11.60 – 23.86 nm using Halder Wagner plots. The most intense peak was at a miller indices (311), which is a characteristic of a spinel ferrites. Nickel substitution brought variation in the lattice constants which were in the range of 8.3436 – 8.4149 Å. Both Williamson – Hall and Halder- Wagner plots revealed all sample to possess compressive micro strain. Further structural properties by Fourier transform spectroscopy showed prominent peak at range of 350 – 450 cm-1 which are vibration of metal oxygen bond in octahedral sites while vibrations at 500 – 600 cm-1 which are vibration in tetrahedral sites, a characteristics of spinel ferrites with metal oxygen bond stretching. Optical properties by UV-Vis showed the samples optical band gap in the range of 4.19 – 4.21 eV, refractive index in the range of 2.048 – 2.562 and optical dielectric constant in the range 5.062 – 5.070. Kelvin probe scans revealed a low potential material and more interesting was the negative surface potential. The work function for the area scan was in the range 4.536 – 4.588 eV while for the line scan was in the range 4.341 – 4.5673 eV. Electrical conductivities of the samples were found to increase with increase in nickel content, this was determined from the calculation of length jump which was found to decrease from 2.975 Å to 2.942 Å. Similar results of variation of electrical conductivity were found by calculation of unshared edges which were found to decrease with nickel content from 6.9773 – 6.9181 Å. In summary, the synthesized nanoferrites have properties which could find their applications in fabrications of effective gas sensors, based on their size, band gap, length jump, and surface potential obtained.
Formulation of Schrödinger Equation Using The Hilbert Space Operators Approach
(Chuka University, 2019-09) Mbatha, Elizabeth
Operators in Hilbert space have properties which are useful in the study of mathematical abstract areas such as approximation theory, Banach Fixed point theory, the spectral theory as well as Quantum Mechanics. Schrödinger equation is a fundamental entity with many applications in Quantum Mechanics. This equation was initially derived by applying the knowledge of electromagnetic wave function and Einstein theory of relativity. Later, it was derived by applying the knowledge of Newtonian mechanics. It was also derived by extending the wave equation for classical fields to photons and simplified using approximations consistent with generalized non-zero rest mass. However, from the existing literature no study has been done on deriving Schrödinger equation using properties of Hilbert space operators. In this study, Hilbert space operators that include unitary operators, self adjoint operators and compact operators, norms of linear operators, Hilbert Schmidt operator, normal operators together with Lebesque Integral, Neumann Integral and spectrum are used in place of the existing concepts of electromagnetic wave function, Einstein theory of relativity and approximation consistent with generalized non zero mass to derive the Schrödinger equation. Furthermore, this study has established the correlation between the electromagnetic wave function and Einstein theory of relativity in relation with Hilbert space operators. Application of Hilbert space operators on Quantum observables such as position, momentum and energy of a particle has been done in these study. The derivation of Schrödinger enhances equation and its application using Hilbert space operators have enhanced a better understanding of the concept of Schrödinger equation. The results of this work will be useful in quantum mechanics as well as in mathematical operator theory.
Modelling and Application of Response Surface Methodology for Optimization of Weight Gain of Eight Weeks Old Kenbro Served With Pumpkin (Cucurbita Pepo L) Seeds Extract
(Chuka University, 2019-09) Kinyua, Charles Mugendi
Extensive use of synthetic growth promoting antibiotics have become a threat to public health. Therefore, there is a need to search for bioactive phytochemicals that have positive effects on immune, growth and appetite status of the chicken. Such bioactive compounds can be obtained from plants. Pumpkin seeds have been found to be a valuable source of protein and bioactive compounds. Mathematical models have been used to study the effect of pumpkin extracts on the weight gain of chicken. However, most of these studies have focused on the levels of the application of pumpkin extract, rather than on optimising the levels of application on the weight gain of the chicken. Optimization is important since it provides information on the amount of pumpkin seed extracts that should be fed to the chicken without wastage. This study was conducted to evaluate the weight gained by the Kenbro chicken served with pumpkin (Cucurbita pepo L) seeds extract and examined the possible combination of the number of weeks and quantity of pumpkin seed extract that can result in maximum weight gain of the Kenbro chicken. The experiment was conducted using Random Complete Block Design at the poultry demonstration unit of Chuka University. Sixty- day old Kenbro chicks were randomly distributed to five treatments which contained 0, 50, 100, 150 and 200 ml of pumpkin seed extracts per litre of water. Each treatment was replicated three times with four chicken per replicate. The birds were fed with the same diets of finisher and starter feeds. The chickens were provided with enough feeds and water ad libitum in the morning at 8 am. The birds were weighed at the beginning of the experiment and thereafter at an interval of three days for eight weeks. Data was analysed using R statistical software. A Response surface model was fitted to the data and subjected to contour plots to characterize the nature of its turning point and to capture the combination of the number of weeks and quantity of pumpkin seed extract that brings maximum weight gain of the Kenbro chicken. The results showed that the average body weight gained was significant (p < 0.05). The birds served with 200 ml pumpkin seed extract for 4 weeks had the highest weight gain. The fitted Response Surface Model indicated that the number of weeks and quantity of pumpkin seed extract together with their interaction significantly (p < 0.05) determined the weight gain of Kenbro chickens. The study found that the quadratic model fitted using the data had an adjusted R-Squared value of 0.78. The optimal weight gain of 0.23 kg was achieved when the number of weeks was 3.18 with 192.40 ml of pumpkin seed extract. The number of weeks, pumpkin seed extract and their interaction play a key role in obtaining maximum weight gain of the Kenbro chicken. These factors should be put into consideration when developing a feeding system for Kenbro chickens. The study also guides the farmers on the optimization of Kenbro chicken production without incurring an extra cost in the input.
Modelling the Effects of Mindfulness Based Stress on Breast Cancer Survival Rate among Women in Meru and Nyeri Counties, Kenya, using Cox Proportional Hazard Model
(Chuka University, 2019-09) Mutwiri, Mwendwa N.
Breast cancer remains the most commonly diagnosed cancer among women, affecting 34 women per every 100,000. This has led to high number of fatalities annually, which need to be mitigated. The main interest among many cancer survivors and their families is establishing other conventional therapies they can engage in to improve their prognosis and survival. Among some of the key therapies is the interest in working on mindfulness-based stress (MBS) that patients undergo after diagnosis as complementary and alternate measures. Regardless of this, there is little that is known about the effects of MBS factors on breast cancer survival. Management of breast cancer can be enhanced through modelling the effects of MBS on breast cancer survival rate. However, there is limited information on accuracy of existing models. This study focused on developing a model to predict the effect MBS factors have on breast cancer survival rate among women in Meru and Nyeri Counties. Both Primary data and Secondary data were used. Primary data was obtained using a structured questionnaire from the breast cancer survivors and the medical practioners while secondary data was obtained from records at Meru teaching and referral hospital and Nyeri level five hospital on the MBS variables (cost burden of treatment, stress on diagnosis, prolonged time taken to access treatment, poor diet, alcohol use, physical activity and lack of awareness) among breast cancer patients for the period 2012 to 2017. Mixed method research design was used in the study. Both quantitative and qualitative data used in the study was analysed using R software. Cox proportional hazard model was used in establishing the survival rates, with the breast cancer survival rate being dependent variable while MBS factors were the independent variables. Kaplain-Meier estimators were used in determining the varying effects which the MBS factors have on survival rate. Log-rank test was used to perform comparisons of survival curves using hypothesis tests on the patients‘ survival rate considering age. The likelihood ratio test showed that MBS factors are significant in predicting hazard rates ( = 66.7, p = 0.0000119). Treatment period was highly statistically significant (p = 0.00014) as compared to other covariates. Lack of awareness (p = 0.0010124), ease of coping with stress (p = 0.000514) and observing the right diet (p = 0.04092) were also found to significantly affect survival rate. Access of treatment immediately after diagnosis, availing the right information to the patients, helping patients to cope easily with stress and observing the right diet were found to be the best estimators in increasing breast cancer survival rate. The study therefore recommends use of the model in predicting breast cancer survival rates which can greatly improve breast cancer prognosis.

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