In this thesis, we present theoretical studies of antiperovskites ANCa3 (A=Ge, Sn, Pb), BCFe3 (B=Al, Zn, Ga), SnCD3 (D=Co and Fe) and MXY3 (M=Al, Ga, Ir, Mg, Pd, Pt, Rh; X=C, N; Y=Mn, Ni, Sc, Ti, Cr, Fe) as well as SbNCa3, BiNCa3, SbNSr3 and BiNSr3. The calculations are carried out with the full-potential linearized augmented plane waves plus local orbital (FPLAPW+lo) method within the framework of density functional theory (DFT) as well as Boltzmann’s theory. The exchange–correlation effects are treated by the local density approximation (LDA), generalized gradient approximation (GGA-PBEsol) and Engel and Vosko GGA (EV-GGA). Furthermore, the modified Becke and Johnson (mBJ) as well as improved mBJ potentials are used for the exact band gaps of the semiconductors. The relativistic effects in some of the compounds under study are explored by spin-orbit coupling. The consistency of the calculated results of the thermoelectric properties of SnCCo3 and SnCFe3 with the experimental results confirms the reliability of our theoretical calculations for the other investigated metallic antiperovskites, ANCa3 (A=Ge, Sn, Pb), BCFe3 (B=Al, Zn, Ga), SnCD3 (D=Co and Fe) and MXY3 (M=Al, Ga, Ir, Mg, Pd, Pt, Rh; X=C, N; Y=Mn, Ni, Sc, Ti, Cr, Fe). Our results for ANCa3 (A=Ge, Sn, Pb), BCFe3 (B=Al, Zn, Ga) and SnCD3 (D=Co, Fe) indicate that the thermopower of these materials can be enhanced by changing the chemical potential. The dimensionless figure of merit for the three nitrides approaches to 0.96 at room temperature, which predicts the usefulness of these materials in thermoelectric devices. Furthermore, the thermal conductivity of these compounds is minimum at room temperature for chemical potential of -0.25 eV to 0.25 eV, with maximum values of dimensionless figure of merit in this range. The striking feature of these studies is identifying a metallic compound, SnNCa3, with the highest value of Seebeck coefficient at room temperature out of all metals. Furthermore, electronic and thermoelectric properties of carbon and nitrogen based twenty metallic antiperovskites MXY3 (M=Al, Ga, Ir, Mg, Pd, Pt, Rh; X=C, N; Y=Mn, Ni, Sc, Ti, Cr, Fe) are investigated. We find high values of Seebeck coefficient and small values of electronic thermal conductivity for AlCTi3, AlNSc3, AlCNi3, AlNTi3, GaCCr3 and MgCNi3 between -0.25 and 0.25 eV chemical potential. These results show high dimensionless figure of merit in metallic materials and therefore, we predict these materials can be potential candidates for low temperature thermoelectric applications. Figure of merit for AlNTi3, GaCCr3, AlCNi3, AlNSc3, MgCNi3 and AlCTi3 materials reaches to 0.32, 0.25, 0.19, 0.19, 0.2 and 0.25 respectively, and hence are predicted to be low temperature thermoelectric materials. The structural, electronic and optical properties of antiperovskite semiconductors, SbNCa3, BiNCa3, SbNSr3 and BiNSr3 are also studied. The calculated lattice constants for these compounds are found consistent with the available experimentally measured values and other theoretical results. The band profiles show that all of these materials are direct band gap semiconductors with the band gap values of 1.1 eV, 1.09 eV, 0.92 eV and 0.81 eV for SbNCa3, BiNCa3, SbNSr3 and BiNSr3 respectively. The direct band gap nature reveals that they may be effective in optical devices and therefore the optical properties of these compounds like the real and imaginary parts of dielectric function, refractive index and absorption coefficient are calculated and discussed. Furthermore, the thermoelectric properties of these semiconductors are also calculated. Our results show high values of Seebeck coefficient for these materials between -0.25 eV and 0.25 eV chemical potential values.
This research is motivated by the ups and downs in the quality of employee performance at PT Enseval Putera Megatrading Pekanbaru Branch from 2020 to 2022. Based on the formulation of the problems that have been made, this study aims to determine the effect of compensation and work environment on employee performance at PT Enseval Putera Megatrading Pekanbaru Branch This research is a type of quantitative research. The sample used in this study were employees of PT Enseval Putera Megatrading Pekanbaru Branch as many as approximately 52 people. Sampling technique by means of Simple Random Sampling. With data collection through observation, interviews, questionnaires and literature studies. The analysis technique in this study uses Multiple Linear Regression Analysis. This study uses multiple linear regression with the help of the SPSS Ver program. 21.00. The results of this study, compensation has a positive effect on employee performance. This is evident from the results of the t test which obtained t count X1 greater than t table, namely the value of t count (7.467) greater than t table (2.010) accepted at a significance level of 5%. The work environment has a positive effect on employee performance. This is evident from the results of the t test which obtained the t count X2 greater than the t table, namely the t value (7.484) greater than the t table (2.010), accepted at the 5% significance level. Compensation and work environment together have a positive effect on employee performance. This is evident from the results of the F test which shows the results of the F count of (415.672) greater than the F table of (3.19) accepted at the 5% significance level. Islamic economic review of the effect of compensation and work environment on employee performance at PT Enseval Putera Megatrading Pekanbaru branch can be categorized as sharia based on ijarah contract.
Breast cancer is a multifactorial and complex disorder. It is posing serious public health concerns and its incidence rate is on the rise in Pakistan. It is therefore of prime importance to identify genetic and/or non-genetic factors contributing towards the development and progression of breast cancer. The present investi gation is a case-control study including 1000 cases and 1000 age matched con trols of the same ethnic background. Individuals were recruited on the basis of a predefined inclusion and exclusion criteria. All participants were in-person di rectly interviewed after signing an informed consent document. Peripheral blood samples were collected from all the participants along with personal identifiers, demographic characteristics and family history of cancer and other diseases. Vital status/survival status of the patients was determined for up to a maximum of 47 months to record the censored data. We analyzed our sequenced variants and clinico-pathologic features for their possible association with the disease risk by using unconditional logistic regression. Association of the variables was measured with ORs and corresponding 95% confidence intervals. Overall survival of the patients was assessed using Kaplan-Meier curve. Cox proportional hazard model was used to calculate risk ratios and to adjust for potential confounders. A total of thirteen variants were reported in BRCA1 and BRCA2 genes respec tively including three novel variants (Exon3 -37insC, Exon3 -215T<C and Exon14 102-103insTC) in BRCA1 and five novels (exon8 +87insA, exon20 +318T<A, exon19 -351-353delTCT, exon16 -17G<T and exon27 T129A) in BRCA2. Five out of thirteen variants were the in silico identified, HapMap confirmed, pathogenic and previously reported in other populations. Their contribution towards disease risk was tested in our sampled population and it was observed that rs28897686 polymorphism of BRCA1 and rs28897743 of BRCA2 were observed positively asso ciated, while rs28897696 and rs1060915 polymorphisms of BRCA1 and rs4987049 SNP of BRCA2 were found not associated with the disease risk. Five of the eight novel variants, two in BRCA1 (-37insC exon 3 and 102-103insTC exon 14) and three in BRCA2 (+87insA exon 8, -351-353delTCT exon 19 and T129A exon 27) xii were observed only in the breast cancer cases and found completely absent in the controls while the rest of 3/8 of the novel variants (BRCA1 -215T<C exon 3, BRCA2 +318T<A exon 20 and BRCA2 -17G<T exon 16) were found highly significantly associated with breast cancer risk. Pairwise Linkage Disequilibrium analysis showed that the strong LD (D0=0.52) exists in between rs28897696 and -215T<C exon 3 variant of BRCA1 and LD (D0=0.43) in between rs28897743 and -17G<T exon 16 of BRCA2. We also examined the cross-sectional associations of life style, reproductive and socio-demographic risk factors with breast cancer density in Pakistani women. Mean age of cases and controls at recruitment was 50.58±10.68 and 54.78±14.52 years while mean BMI for cases and controls was 26.07±4.04 and 25.05±4.25, respectively. Among the patients 60.70% were married, 46.50% were nulliparous, 16.90% had≥4 children, 39.90% women breast fed their children, 88.90% were nonsmokers and 67.90% were physically active. Post-menopausal women diagnosed with breast cancer accounted for 52.30%. In the current data set, 31.70% patients had at least a blood relative diagnosed with some type of cancer, 22.80% patients were diagnosed with other types of medical complications including high blood pressure, diabetes etc. Significant association between age and breast cancer was observed. Overweight (BMI≥25) and obese (BMI≥30) females have approximately 1.5 times more risk of having breast cancer (Overweight; OR = 1.52, 95% CI: 1.28-1.81 and Obese; OR = 1.41, 95% CI: 1.14-1.74). It was also observed that unmarried women were at more than two fold higher risk. Similarly use of oral contraceptives and smoking were also significantly associated with increasing risk of breast cancer. Individuals who were physically inactive were recorded to be 1.27 times more likely to develop breast cancer. We have found approximately 1.34 fold increase in the disease risk among the postmenopausal patients (OR = 1.34, 95% CI: 1.14-1.58). Breast cancer patients were observed having an overall median survival time of 33 months (95% CI: 28-34). In this present study we attempted to define the genetic and non-genetic basis responsible for breast cancer incidence among Pakistani population. It can be concluded that there is a significant contribution of BRCA1 and BRCA2 genetic alterations in breast cancer pathogenesis. It is hoped that our findings will be of great importance to establish adequate evidence-based awareness and preventative measures against breast cancer in Pakistani women.