School of Biological and Physical Sciencehttps://repository.maseno.ac.ke/handle/123456789/882024-03-28T20:14:02Z2024-03-28T20:14:02ZConvergence of the Laplace and the alternative multipole expansion approximation series for the Coulomb potentialJobunga, EOWandera, COOkeyo, OShttps://repository.maseno.ac.ke/handle/123456789/60662024-03-26T13:20:01Z2023-09-25T00:00:00ZConvergence of the Laplace and the alternative multipole expansion approximation series for the Coulomb potential
Jobunga, EO; Wandera, CO; Okeyo, OS
Multipole expansion is a powerful technique used in many-body physics to solve dynamical problems involving correlated interactions between constituent particles. The Laplace multipole expansion series of the Coulomb potential is well established in literature. We compare its convergence with our recently developed perturbative and analytical alternative multipole expansion series of the Coulomb potential. In our working, we confirm that the Laplace and the analytical alternative multipole expansion series are equivalent as expected. In terms of performance, the perturbative alternative multipole expansion series underapproximate the expected results to some extent while the Laplace and the analytical alternative multipole expansion series yield results which are relatively accurate but oscillatory in nature even with a higher number of angular momentum terms employed. As a practical example, we have evaluated the Slater double integrals for two-electron systems using the multipole expansion techniques and a mean field approximation. The estimated results show that only spherical interactions are dominant while the higher-order interactions are negligible. To highlight the discrepancy in the application of each of the formulations of the multipole expansion series for the electron-electron interaction potential, an estimation of the non-relativistic groundstate energies of some helium-like systems, evaluated using the spherical approximation of the multipole potential, is provided. Our findings are likely to be useful in the treatment of the Coulomb potential in electronic structure calculations as well as in celestial mechanics.
https://www.nature.com/articles/s41598-023-42724-8
2023-09-25T00:00:00ZContribution of sustainability strategies to the growth and development of licensed fast-food restaurant: a case of lake region economic block, KenyaNyamogosa, HenryMurimi, Michaelhttps://repository.maseno.ac.ke/handle/123456789/60582024-03-21T17:08:02Z2023-09-01T00:00:00ZContribution of sustainability strategies to the growth and development of licensed fast-food restaurant: a case of lake region economic block, Kenya
Nyamogosa, Henry; Murimi, Michael
The study aimed to investigate the influence of sustainable strategies on the growth and
development of licensed fast-food restaurants (FFRs) in Kenya. It sought to determine the impact of
economic, social, and environmental sustainability strategies on the FFR’s growth and development.
The study utilized a quantitative approach and employed a cross-sectional survey design. A total of
452 licensed FFRs from Lake Region Economic Block (LREB), Kenya, were targeted in the study.
Stratied and proportionate sampling methods were utilized to select 208 fast-food restaurant
managers from the 452 licensed FFRs. The findings of the study revealed that environmental
sustainability strategies with ß value of 0.241, economic sustainability strategies with ß value of 0.175,
and social sustainability strategies with a ß value of 0.172 influence the growth and development of
FFRs. The results imply that a single unit change in environmental, economic, and social sustainability
strategies would result in a 0.241, 0.175, and 0.172 increase in FFR growth and development,
respectively. The paper’s empirical evidence reveals that environmental sustainability strategies are
more important to the growth and development of FFRs than economic and social sustainability
strategies. Further, the regression model results implied that the three predictors, environmental,
economic, and social sustainability strategies, provide a 26.8% explanation of the variance in FFR
growth and development. The findings implications are discussed about adopting and
implementing environmental sustainability strategies in FFRs to maintain a high standard of service
and boost FFR’s growth and development. The paper suggests that fast-food restaurants must fully
embrace sustainable business strategy applications to fully realize and maximize benefits related to
sustainable business strategies, such as increased profit, market share, improved customer approval
levels, increased resilience to disasters, and a reduced staff turnover rate.
2023-09-01T00:00:00ZCharacterization of atomic state evolution in the JC and anti-JC models: spin-displaced field modes in the quantum Rabi modelOmolo, Joseph Akeyohttps://repository.maseno.ac.ke/handle/123456789/60572024-03-21T14:25:18Z2023-03-20T00:00:00ZCharacterization of atomic state evolution in the JC and anti-JC models: spin-displaced field modes in the quantum Rabi model
Omolo, Joseph Akeyo
In this article, characterization of the atomic state evolution in the Jaynes-Cummings (JC) and anti-Jaynes-Cummings (aJC) models means using the reduced atomic state degree of purity, concurrence and spin excitation number to determine the ranges and critical values of the mean photon number and frequency detuning parameters at which the atom is in a disentangled pure, mixed or entangled state. By unifying the mean photon number amplitude and detuning parameters in a simple relation, leaving the mean photon number as the only variable parameter, we have discovered a beautiful natural evolution property where the atom is in a uniformly mixed state describing symmetrical stable evolution of collapses and revivals of the degree of purity and concurrence, one above and the other below, a uniformly mixed state axis through points of equal degree of purity and concurrence at 1√
2023-03-20T00:00:00ZA Comparative Thermodynamic Study of AlF3, ScF3, Al0.5Sc0.5F3, and In0.5Sc0.5F3 for Optical Coatings: A Computational StudyAlruqi, Adel BandarOngwen, O. Nicholashttps://repository.maseno.ac.ke/handle/123456789/60532024-03-19T18:20:18Z2023-11-27T00:00:00ZA Comparative Thermodynamic Study of AlF3, ScF3, Al0.5Sc0.5F3, and In0.5Sc0.5F3 for Optical Coatings: A Computational Study
Alruqi, Adel Bandar; Ongwen, O. Nicholas
Optical coatings are thin layers of materials applied to optical components in order to modify the transmission, reflection, or polarization properties of light. The common materials used for optical coatings include magnesium fluoride (MgF2
), scandium trifluoride (ScF3
), and aluminum trifluoride (AlF3
), owing to their desirable optical properties, spectral range, and compatibility with substrates. However, each of these materials has its own drawbacks. For instance, AlF3
has been found to exhibit limited resistance to attack by chemicals, as well as poor thermal stability, while MgF2
has low durability, as well as being hygroscopic. In this study, we undertook ab initio calculations in order to compare the thermal properties of AlF3
, ScF3
, Al0.5Sc0.5F3
, and In0.5Sc0.5F3
in order to obtain the best material for optical coatings. MgF2
was also included in the study as a reference. The calculations used PBE pseudopotentials and the extended generalized gradient approximation within the quantum espresso algorithm. The study demonstrated that the computed results agree with the information found in the literature. ScF3
exhibited a negative coefficient of thermal expansion, unlike the other four. Moreover, AlF3
was found to be the best candidate for optical coatings that are used in high-power laser systems with high thermal dissipation, due to its superior thermal expansion coefficient as well as its better response to thermal stress. The large variation between the cp
and cv
of ScF3
is not desirable. Moreover, due to its negative thermal expansion coefficient, ScF3
is not thermally stable. The highest thermal stability was exhibited by In0.5Sc0.5F3
. Since Al0.5Sc0.5F3
and In0.5Sc0.5F3
have been modeled in this study for the first time, experimental determination of their crystal structures needs to be investigated.
2023-11-27T00:00:00ZStructural and Mechanical Properties of NbN Alloyed with Hf, In, and Zr for Orthopedic Applications: A First-Principles StudyAlruqi, Adel BandarOngwen, O. Nicholashttps://repository.maseno.ac.ke/handle/123456789/60522024-03-19T18:13:55Z2024-01-17T00:00:00ZStructural and Mechanical Properties of NbN Alloyed with Hf, In, and Zr for Orthopedic Applications: A First-Principles Study
Alruqi, Adel Bandar; Ongwen, O. Nicholas
The search for biocompatible, non-toxic, and wear-resistant materials for orthopedic implant applications is on the rise. Different materials have been investigated for this purpose, some of which have proved successful. However, one challenge that has proven difficult to overcome is the balance between ductility and hardness of these materials. This study employed ab initio calculations to investigate the structural and mechanical properties of niobium nitride (NbN) alloyed with hafnium, indium, and zirconium, with the aim of improving its hardness. The calculations made use of density function theory within the quantum espresso package’s generalized gradient approximation, with Perdew–Burke–Ernzerhof ultrasoft pseudopotentials in all the calculations. It was found that addition of the three metals led to an improvement in both the shear and Young’s moduli of the alloys compared to those of the NbN. However, both the bulk moduli and the Poisson’s ratios reduced with the introduction of the metals. The Young’s moduli of all the samples were found to be higher than that of bone. The Vickers hardness of the alloys were found to be significantly higher than that of NbN, with that of indium being the highest. The alloys are therefore good for wear-resistant artificial bone implants in ceramic acetabulum, and also in prosthetic heads.
2024-01-17T00:00:00ZInvestigating the Young's modulus of Cu-Al-Be shape memory alloy using a phase diagram, vibration spectroscopy and ultrasonic wavesBenlachemi, RaniaOgam, ErickOngwen, NicholasBoudour, AmarFellah, Zine El Abiddinehttps://repository.maseno.ac.ke/handle/123456789/60512024-03-19T18:07:52Z2024-03-05T00:00:00ZInvestigating the Young's modulus of Cu-Al-Be shape memory alloy using a phase diagram, vibration spectroscopy and ultrasonic waves
Benlachemi, Rania; Ogam, Erick; Ongwen, Nicholas; Boudour, Amar; Fellah, Zine El Abiddine
This work presents a method for determining the effective Young’s modulus (Eeffective) and Poisson ratio of small specimens of a ternary shape memory alloy (SMA), Cu-Al-Be. The alloys were synthesized uniformly and homogeneously using various concentrations of high purity metals and formed into slabs of different geometrical shapes. The phases and fractional quantities of each sub-alloy composing the SMA were determined using SEM/EDS data and the lever rule, and confirmed by matching computed and measured X-ray diffraction peak patterns. The Eeffective was determined using the rule of mixtures, employing elastic moduli obtained from Ab initio (Density functional theory) calculations. To address the challenge of determining Eeffective experimentally for small specimens, high frequency ultrasonic waves and vibration spectroscopy were used. The Eeffective was then used in a 3D finite element model to compute the vibrational spectrum’s resonance peaks, which were found to match those of the experimental vibrational response. The Eeffective was also compared to the pressure wave (P-waves) modulus recovered using non-contact ultrasound waves propagating through the sample’s thickness. Discrepancies mainly occurring for alloys with the β phase were resolved by determining its anisotropic spatial Young’s modulus. Overall, the presented method provides a comprehensive characterization of the mechanical properties of small alloy specimens.
The article can be accessed in full: https://doi.org/10.1016/j.jallcom.2023.173010
2024-03-05T00:00:00ZAssessment Of Ricinus Communis Ml Crude Extracts Towards Urinary Tract Infection Strains With Their Associated AilmentsOchieng, O. AnthonyMohamed, A.NasifKowanga, K. Davidhttps://repository.maseno.ac.ke/handle/123456789/60402024-03-16T08:38:30Z2022-09-30T00:00:00ZAssessment Of Ricinus Communis Ml Crude Extracts Towards Urinary Tract Infection Strains With Their Associated Ailments
Ochieng, O. Anthony; Mohamed, A.Nasif; Kowanga, K. David
Cases of synergic Urinary Tract Infections with its associated ailments has become a menace. Due to its high costs
of treatment, unavailability of relevant antibiotics, misdiagnosis and recurrence, most patients within Africa SubSahara regions prefer ethnopharmacological ways of taking boiled and sieved liquid concoction made from mature
leaves (ML) of ricinus communis to clear the urinary tract system from these microbes with their associated
ailments. Crude extracts of methanol, chloroform, hexane, and Diethylether prepared from ricinus communis dried
powered mature leaves were subjected to phytochemical screening, antibacterial, GC/MS and antioxidant assays.
Crude methanolic and chloroform extracts prepared from a mixture of coarsely powdered dried twigs and mature
leaves were evaluated for cytotoxic activity on cancer cell line (HCT-116 and K-562). Antibacterial assay of the
crude extracts reveals recommendable range of values categorized as moderate and high sensitive with respect to
the standard measure. Methanol extract exhibited antibacterial activities against all gram-positive and gramnegative bacterial species while diethylether extract showed its potency against the gram-positive staph only among
escherichia, klebsiella and pseudomonas species. Chloroform, diethylether and hexane crude extracts proven to be
inert against pseudomonas strain. Highest scavenging capacity range obtained is 60.38 ± 0.034 percent while the
lowest cytotoxicity range is 20.18 ± 1.37 μg/ml-1revealing the medicinal value and safeness of the plant extract.
Phytochemical analysis and GC/MS results revealed the presence of phytoconstituents and museum of bioactive
agents with antibacterial, antifungal, antiviral, anti-inflammatory, anticancer, antidiarrheal, antimutagenic and antioxidant properties thus ascertaining its efficacy towards the infection with associated ailments.
2022-09-30T00:00:00ZGlass photonics meets photovoltaics: general principles and a case studyOtieno, FrancisAiro, MildredQuandt, AlexWamwangi, DanielErasmus, M. Rudolphhttps://repository.maseno.ac.ke/handle/123456789/60382024-03-16T07:58:51Z2023-11-01T00:00:00ZGlass photonics meets photovoltaics: general principles and a case study
Otieno, Francis; Airo, Mildred; Quandt, Alex; Wamwangi, Daniel; Erasmus, M. Rudolph
In this study, we present a promising combination of glass photonics and photovoltaics to develop more efficient types of solar cells. Following up on earlier suggestions, we demonstrate that fundamental losses due to the intrinsic spectral mismatch of many photovoltaic devices can be ameliorated using spectral conversion based on rare-earth-doped glass layers. Our goal is to show work in progress in this field by approaching the topic in two ways: First, we will give a brief introduction to the basic concepts of photovoltaic devices and their intrinsic losses. Within this standard conceptual framework, we suggest that gains in efficiency due to spectral conversion layers can be described by an alternative model of absorbing and emitting solar cells, which is based on radiative transfer. Second, we practically demonstrate spectral conversion in a real device, which combines Tb-doped ZnO thin films with a typical organic solar cell. To this end, we describe in detail the fabrication of such a device using RF sputtering, carry out a typical characterization of the glass layer using Raman spectroscopy and analyze the performance of the final device.
The article can be accessed in full via Springer link:https://link.springer.com/article/10.1140/epjp/s13360-023-04714-7
2023-11-01T00:00:00ZCauses and Consequences of Post-Election Violence in KenyaOchieng, Charles. P. Otienohttps://repository.maseno.ac.ke/handle/123456789/60282024-03-14T13:28:27Z2023-10-05T00:00:00ZCauses and Consequences of Post-Election Violence in Kenya
Ochieng, Charles. P. Otieno
The election of leaders by the people is the aim of democratic procedures. An electoral system is intended to ensure that the
outcomes reflect the preferences of the majority of voters, providing elected officials’ legitimacy, and that the results are
unchallenged in any form. The aim of this study was to identify the causes of the post-election violence. Voting theory served as
the foundation for this work. A descriptive study approach using both qualitative and quantitative methods was used by the
researcher. The research was carried out from July 2022 to December 2022. Political parties, political analysts, IEBC members,
legislators, and voters made up the study's target population. The researcher employed the stratified random sampling technique.
The target population established the strata, and a random sample was taken from each stratum. The researcher used interview
guide techniques to collect data, using items that were developed from the study objectives and research questions.
Questionnaires and interviews were the two main ways that data were gathered. Voters were handed questionnaires, and
interview guidelines were provided for political experts, electoral experts, and IEBC officials. The information gathered through
the use of questionnaires was statistically analyzed using descriptive methods. According to the findings, disputed election results,
tribalism, inadequate electoral conflict resolution mechanisms, the "winner-takes-it-all" election system, perceived bias of the
electoral management body, and voter incitement by politicians are among the main causes of post-election violence in Kenya
since 1963. Casualties, internally displaced people, the damage to private and public property, economic instability, and
emotional and psychological suffering are only a few of the key effects of the post-election violence in Kenya. The report
recommends, among other things, looking at alternative choices, including mixed-member and proportional representation
models, since they are more inclusive and produce fair representation, as a remedy for the existing polarizing plurality voting
system.
2023-10-05T00:00:00ZComparative Efficacy of Levofloxacin Versus Amoxycillin/Clavulanic Acid Combined with Azithromycin in Treatment of Community-Acquired PneumoniaMusungu, VincentOnguru, DanielOnyango, Patrickhttps://repository.maseno.ac.ke/handle/123456789/60252024-03-13T16:10:06Z2024-03-06T00:00:00ZComparative Efficacy of Levofloxacin Versus Amoxycillin/Clavulanic Acid Combined with Azithromycin in Treatment of Community-Acquired Pneumonia
Musungu, Vincent; Onguru, Daniel; Onyango, Patrick
Community-acquired pneumonia (CAP) is an important cause of mortality and morbidity worldwide. Early initiation of antibiotics is highly recommended. In most CAP cases, multiple drug options are increasingly becoming available, but there is often a lack of evidence that allows for a direct comparison of the efficacy of one drug versus another.
https://doi.org/10.59652/aim.v2i1.112
2024-03-06T00:00:00Z