Refinement Program Research Articles

Optimum Levenberg–Marquardt constant determination for nonlinear least-squares

A new method for determining an approximate optimum value for the Levenberg–Marquardt constant has been shown to improve the convergence rate of nonlinear least-squares problems including complex X-ray powder diffraction and single-crystal structural refinements. In the Gauss–Newton method of nonlinear least squares, a lower value for the objective function is occasionally not realized after solving the matrix equation AΔp = b. This situation occurs when either the objective function is at a minimum or the A matrix is ill conditioned. Invariably the Levenberg–Marquardt method is used, where the matrix equation is reformulated to (A + λI)Δp = b and λ is the Levenberg–Marquardt constant. The values chosen for λ depend on whether the objective function increases or decreases. This paper describes a new method for setting the Levenberg–Marquardt constant, as implemented in the computer program TOPAS-Academic Version 7, which in general results in an increased rate of convergence and additionally a lowering of the objective function as a function of starting parameter values. The reduction in computation is problem dependent and ranges from 10% for typical crystallographic refinements to 50% for large refinements. In addition, the method can be applied to general functions including cases where the objective function comprises both the sum of squares and penalties including functions with discontinuities. Of significance is the trivial extra computational effort required in determining λ as well as the simplicity in carrying out the calculation; the latter should allow for easy implementation in refinement programs.

Aurivillius family of layered perovskites, BiREWO6 (RE = La, Pr, Gd, and Dy): Synthesis, characterization, and photocatalytic studies

The present work deals with the synthesis, characterization, and photocatalytic studies of layered perovskites belonging to Aurivillius family. Layered perovskites of various chemical compositions, BiREWO 6 (RE = La, Pr, Gd, and Dy), were synthesized by an ethylene glycol–assisted sol–gel method. These materials were characterized by X-ray diffraction, scanning electron microscopy–energy dispersive spectroscopy (EDS), Fourier transform infrared, Raman, and ultraviolet–visible diffuse reflectance techniques. The composition of all these materials was obtained from EDS. The unit cell lattice parameters were attained from Rietveld refinement program, Fullprof.2k, by refining the d-lines of BiREWO 6 . The band gap energy of these samples was obtained from the Kubelka–Munk plot. The photocatalytic activity of all the samples was evaluated by photodegradation of methylene blue. The mechanistic degradation pathway of methylene blue was studied using radical quenchers.

How Do Mortgage Refinances Affect Debt, Default, and Spending? Evidence from HARP

We use quasi-random access to the Home Affordable Refinance Program (HARP) to identify the causal effect of refinancing into a lower-rate mortgage on borrower balance sheet outcomes. Refinancing substantially reduces borrower default rates on mortgages and other debt. Refinancing also causes borrowers to expand their use of debt instruments, such as auto loans, home equity lines, and other consumer debts that are proxies for spending. Borrowers that appear more constrained ex-ante grow these debts more strongly after refinancing but also pay down credit card balances by more. These borrowers also have lower take-up of the refinancing opportunity.

Crystal structure, thermal expansion and long-term behaviors of SmBaCoO5+δ as cathode for intermediate-temperature solid oxide fuel cells

SmBaCo2O5+δ (SBC) was studied as cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The crystal structure, thermal expansion behavior, and electrochemical performance with long-term operation of SBC were characterized. An orthorhombic layered perovskite structure was observed in SBC cathode by a GSAS program for refinement. The average thermal expansion coefficient (TEC) is 21.6 x 10-6K-1 in the temperature range of 100oC-800oC. For long-term testing, the polarization resistance of SBC cathode increases gradually from 25.77 Ω cm2 for 2 h to 38.77 Ω cm2 for 96 h at 600°C, and an increasing-rate for polarization resistance is around 13,8% h-1. Based on the electrochemical properties, SBC cathode with mixed ionic and electronic conductor (MIEC) behavior is a potential cathode for intermediate temperature solid oxide fuel cells based on a SDC electrolyte.

New model of ethylene glycol intercalate in smectites for XRD modelling

Abstract Several models of ethylene glycol (EG) intercalates were implemented in computer programs which are used to simulate XRD patterns of oriented clay minerals. So far the models assumed distributions of atomic positions perpendicular to the c* direction with similar or significantly higher temperature coefficients B for the EG molecules (B = 1 A2 or 11 A2) than for atoms of crystal structure (approximately: B = 1 A2). The temperature coefficients for the interlayer H2O molecules and Ca2 + cations (B = 1 A2 or 1.68 A2) were close to these of clay minerals' atoms. This assumption is in disagreement with the distributions described recently with molecular dynamics (MD) simulations. An adjustable model of one and two EG planes in the interlayer is provided in this study. This new model is based on the results of MD simulations. A wide range of EG and H2O contents were considered in the simulated structures. Theoretical structures corresponding to certain basal spacings were chosen as representative for one- and two-plane intercalates. The electronic density profiles of EG molecules, H2O molecules, and Ca2 + ions were fitted with Gaussian functions. Their number was minimized to achieve the simplest but yet flexible model of the interlayer structures. The obtained new models show significant differences with regard to the former ones; especially in the atoms' positions. Based on the MD results, it was also possible to determine the relationships between positions of the atoms/molecules and basal spacing. For some atoms was also a relationship between basal spacing and intensity ratio of Gaussian distributions found. Temperature factors for interlayer species were larger than in the former models and Ca2 + ions can exist both as inner-sphere and/or outer sphere complexes, while its ratio can be optimized. All the relationships were implemented in the BGMN Rietveld refinement program. Using the new model it is possible to receive slightly better or similar matching between experimental and theoretical X-ray diffractograms, comparing to the former models. The new model shows limitations due to the fact that electronic distributions of water and EG molecules in the interlayer space are quite similar. Therefore, EG and water molecules in the interlayer space were not treated fully separately during the minimalization procedure.

Molecular docking and molecular dynamics simulations of fumarate hydratase and its mutant H235N complexed with pyromellitic acid and citrate.

Fumarase catalyzes the reversible, stereospecific hydration/dehydration of fumarate to L-malate during the Kreb's cycle. In the crystal structure of the tetrameric fumarase, it was found that some of the active site residues S145, T147, N188 G364 and H235 had water-mediated hydrogen bonding interactions with pyromellitic acid and citrate which help to the protonation state for the conversion of fumarate to malate. When His 235 is mutated with Asn (H235N), water-mediated interactions were lost due to the shifting of active site water molecule by 0.7 Å away. Molecular dynamics (MD) simulations were also carried out by NAMD and analyzed using Assisted Model Building with Energy Refinement (AMBER) program to better understand the conformational stability and other aspects during the binding of pyromellitic acid and citrate with native and mutant FH. The role of hydrogen bonds and hydrophobic interactions was also analyzed. The present study confirms that the H235N mutation has a major effect on the catalytic activity of fumarase which is evident from the biochemical studies.

Race, uneven recovery and persistent negative equity in the southeastern United States

ABSTRACTI analyze neighborhoods with persistent negative equity in the Southeast to understand whether persistent negative equity can be explained by the same factors that led to the crash or whether dynamics during the recovery period are more relevant. Negative equity is high in the Southeast and concentrated in urban areas. In a series of regressions, I evaluate the contribution of income, commute times, unemployment, housing stock quality, vacancy rates, mortgage market factors, and racial/ethnic composition to rates of negative equity. I also provide within-state and within-metropolitan estimates. I find that even after controlling for subprime lending, the severity of the housing market crash, and other factors, the places with persistent high negative equity are in predominantly Black ZIP codes. Other correlates with persistent negative equity are longer commute times, higher unemployment rates, and high rental vacancy rates. Even after controlling for factors relating to the housing market crash, race remains the strongest predictor of persistent negative equity. This finding indicates that though subprime lending and the foreclosure crisis exacerbated racial and spatial inequality, the recovery itself has also been uneven and has proceeded in a way that widens the racial gap in housing wealth. To further explore the dynamics of the recovery, I provide preliminary evidence that recovery efforts like refinances of Home Affordable Refinancing Program–eligible loans were less likely to be performed in predominantly Black neighborhoods.

Impact of K-compensation on phase fraction, dielectric permittivity, remnant polarization and piezoelectric constant of sodium potassium bismuth titanate ceramics

Sodium potassium bismuth titanate ceramics (NKBTx) has been considered as a potential replacement material to lead-based one due to its moderate piezoelectric constant and high Curie temperature. Recently, the piezoelectric constant and remnant polarization of NKBTx ceramics with x = 0.20 mol fraction has been improved by considering the hygroscopic nature and volatility of K2CO3. In the present work, detailed structural information of K-compensated NKBTx ceramics has been examined using Rietveld refinement program. Samples with three different mole fractions (x = 0.10, 0.20 and 0.30) were synthesized using solid-state reaction method. Not like in earlier reports, x = 0.10 and 0.30 mol fraction samples also have a mixture of rhombohedral and tetragonal phases which are revealed from Rietveld refinement. The presence of superlattice reflection $$\tfrac{1}{2}{\left\{ {311} \right\}_{pc}}$$ near 38° indicated that the existing rhombohedral phase has R3c symmetry in x = 0.10 mol fraction. Where as in x = 0.20 and 0.30 mol fraction samples, satisfactory profile fitting is obtained with rhombohedral (R3m) + tetragonal (P4mm) mixed phase structural model due to the absence of superlattice reflection. Grain growth is suppressed with the addition of xmole fraction and it is evidenced from the microstructure. Reduction of dielectric permittivity and slight shifting of phase transition temperature toward high temperature with increase in frequency indicates, all the samples have relaxor in nature. Temperature at which the dielectric permittivity maximum (T m ) increased from 325 to 345 °C with increase in x-mole fraction from 0.10 to 0.30 respectively. It is revealed from the modified Curie–Weiss law that the degree of diffusion (γ) is reduced from 1.95 to 1.71 with increase in x-mole fraction. Large remnant polarization, relative permittivity and piezoelectric constant are obtained for x = 0.20 composition and they are 21 μC/cm2, 4530 (at 5 KHz) and 215 pC/N respectively. Consolidated results reveals the extension of MPB region is strongly attributed to the K+ and Bi3+ compensation and the obtained electrical properties are associated with the phase fraction of end members as exhibited in lead-based piezoelectric ceramics.

Dance for Health: An Intergenerational Program to Increase Access to Physical Activity

PurposeThe purpose of this study was to evaluate Dance for Health, an intergenerational program to increase access to physical activity in an underserved, high risk urban community. Design and MethodsDance for Health was developed using community-based participatory research methods and evaluated using an observational study design. The program entailed two hour line dancing sessions delivered by trained dance instructors in the neighborhood recreation center. The weekly sessions were delivered for one month in the spring and one month in the fall from 2012–2016. Nurse practitioner students mentored local high school students to assess outcomes: achievement of target heart rate, Borg Rating of Perceived Exertion, number of pedometer steps during dance session, Physical Activity Enjoyment Scale, and adiposity. Analytic methods included descriptive statistics and mixed effects models. ResultsFrom 2012–2016, 521 participants ranging from 2–79 years attended Dance for Health. Approximately 50% of children and 80% of adults achieved target heart rate. Achievement of target heart rate was not related to perceived exertion, though it was related to pedometer steps in adults. All participants rated the program highly for enjoyment. There was no change in adiposity. ConclusionsDance for Health demonstrated high levels of community engagement and enjoyment. It led to adequate levels of exertion, particularly for adults. Our evaluation can inform program refinement and future intergenerational physical activity programs. Practice ImplicationsDance is an enjoyable, culturally appropriate, low cost method for increasing access to physical activity for children and families.

Numerical study of detonation diffraction through 90-degree curved channels to expansion area

The adaptive mesh refinement program AMROC was adopted to conduct numerical study of detonation diffraction through 90-degree curved channels to expansion area. The detonation diffraction processes through straight and curved channels were compared. The effect of curved channel on the re-initiation of diffracted detonation and its mechanism were analyzed in depth. The influence of curvature radius on the deflection of detonation front was discussed. Results indicate that the detonation wave is highly asymmetric when diffracted through the curved channel, which results in the wave front deflection with a certain angle. The value of deflection angle θ decreases with the increase of inner wall curvature radius r0, while the deflecting direction is the same as the propagating direction of the triple point in the Mach reflection. The utilization of the curved channel can promote the re-initiation of diffracted detonation. The mechanism of this promoting effect is the redistribution of detonation energy produced by the interaction from the curved boundaries, which concentrates most of the energy into the compressed area to initiate local detonation and realizes re-initiation eventually. The promoting effect is weakened as r0 gets enlarged and the initial pressure p0 decreases. The critical condition for the re-initiation of diffracted detonation wave through the curved channels was obtained by analyzing the detonation re-initiation results.

AceDRG: a stereochemical description generator for ligands.

The program AceDRG is designed for the derivation of stereochemical information about small molecules. It uses local chemical and topological environment-based atom typing to derive and organize bond lengths and angles from a small-molecule database: the Crystallography Open Database (COD). Information about the hybridization states of atoms, whether they belong to small rings (up to seven-membered rings), ring aromaticity and nearest-neighbour information is encoded in the atom types. All atoms from the COD have been classified according to the generated atom types. All bonds and angles have also been classified according to the atom types and, in a certain sense, bond types. Derived data are tabulated in a machine-readable form that is freely available from CCP4. AceDRG can also generate stereochemical information, provided that the basic bonding pattern of a ligand is known. The basic bonding pattern is perceived from one of the computational chemistry file formats, including SMILES, mmCIF, SDF MOL and SYBYL MOL2 files. Using the bonding chemistry, atom types, and bond and angle tables generated from the COD, AceDRG derives the `ideal' bond lengths, angles, plane groups, aromatic rings and chirality information, and writes them to an mmCIF file that can be used by the refinement program REFMAC5 and the model-building program Coot. Other refinement and model-building programs such as PHENIX and BUSTER can also use these files. AceDRG also generates one or more coordinate sets corresponding to the most favourable conformation(s) of a given ligand. AceDRG employs RDKit for chemistry perception and for initial conformation generation, as well as for the interpretation of SMILES strings, SDF MOL and SYBYL MOL2 files.

Polder maps: improving OMIT maps by excluding bulk solvent.

The crystallographic maps that are routinely used during the structure-solution workflow are almost always model-biased because model information is used for their calculation. As these maps are also used to validate the atomic models that result from model building and refinement, this constitutes an immediate problem: anything added to the model will manifest itself in the map and thus hinder the validation. OMIT maps are a common tool to verify the presence of atoms in the model. The simplest way to compute an OMIT map is to exclude the atoms in question from the structure, update the corresponding structure factors and compute a residual map. It is then expected that if these atoms are present in the crystal structure, the electron density for the omitted atoms will be seen as positive features in this map. This, however, is complicated by the flat bulk-solvent model which is almost universally used in modern crystallographic refinement programs. This model postulates constant electron density at any voxel of the unit-cell volume that is not occupied by the atomic model. Consequently, if the density arising from the omitted atoms is weak then the bulk-solvent model may obscure it further. A possible solution to this problem is to prevent bulk solvent from entering the selected OMIT regions, which may improve the interpretative power of residual maps. This approach is called a polder (OMIT) map. Polder OMIT maps can be particularly useful for displaying weak densities of ligands, solvent molecules, side chains, alternative conformations and residues both in terminal regions and in loops. The tools described in this manuscript have been implemented and are available in PHENIX.

FAULTS: a program for refinement of structures with extended defects

The FAULTS program is a powerful tool for the refinement of diffraction patterns of materials with planar defects. A new release of the FAULTS program is herein presented, together with a number of new capabilities, aimed at improving the refinement process and evolving towards a more user-friendly approach. These include the possibility to refine multiple sets of single-crystal profiles of diffuse streaks, the visualization of the model structures, the possibility to add the diffracted intensities from secondary phases as background and the new DIFFaX2FAULTS converter, among others. Three examples related to battery materials are shown to illustrate the capabilities of the program.

Synthesis, Structure and Electrochemical Properties of Garnet-like Lithium Conductor Li7-X-3yAl y La3Zr2-X Ta x O12

Fast lithium-ion conductors are key materials for the development of next generation energy storage devices such as all-solid-state lithium secondary batteries and rechargeable lithium-air batterie[1,2]. Among the fast lithium-ion conductors reported, garnet-like Li7La3Zr2O12 (LLZ) and its derivatives are one of the most promising materials because of their excellent chemical and electrochemical stability with lithium metal[2,3]. The substitution of Ta5+ in LLZ results in the highest ionic conductivities among the garnet-like compounds[3,4]. However, the contamination of Al3+ from Al2O3 crucible occurs during the synthesis. The difficulty in the determination of the Li+ and Al3+contents has impeded understanding of the conduction properties of these compounds. Therefore, we have investigated the phase relation in the Li7-x-3y Al y La3Zr2-x Ta x O12 system. We began by investigation of the phase relations in the pseudo-binary Li5La3Ta2O12–Li7La3Zr2O12 system, and then extended the investigation to the Al-doped system. Al-free Li7-x La3Zr2-x Ta x O12 pellets were fired in a magnesia crucible to avoid contamination with Al. To prevent the formation of the low-temperature cubic phase, which is easily formed by the Li+/H+exchange reaction with moisture in air below 400 °C, the samples obtained were annealed in an inert atmosphere prior to measurements. The structure and conduction properties of these compounds were then investigated using neutron diffraction, and AC impedance and nuclear magnetic resonance (NMR) spectroscopies. The relationship between the structure and ionic conductivity is discussed based on the results obtained. Polycrystalline Li7-x-3y Al y La3Zr2-x Ta x O12 (x = 0–2.0, y = 0–0.14) was synthesized by solid-state reaction. Phase identification was conducted using XRD (Rigaku RINT 2500 and Bulker D8) with Cu Kα radiation. Diffraction data were collected at each 0.02° step width in the 2θ range from 10 to 80°. Neutron diffraction data were corrected using time-of-flight (TOF) diffractometers: iMATERIA (BL20). Structural parameters were refined using the Rietveld refinement programs Z-Rietveld and Topas Ver. 4 for neutron diffraction and XRD data, respectively. The Li, La, Zr, Ta, Mg and Al compositions were analyzed using inductivity coupled plasma-optical emission spectroscopy (ICP-OES; Agilent Technologies ICP-OES 710). The ionic conductivity was measured by the AC impedance method using a frequency response analyzer (Solartron 1260) in the frequency range of 0.1 Hz to 1 MHz and in the temperature range from -20 to 100 °C in an inert gas atmosphere. Lithium diffusion in the bulk was determined from pulsed-gradient spin-echo (PGSE) NMR measurements. The tetragonal phase formed at x = 0–0.375 and the cubic phase appeared with x = 0.4–2.0 in the Li7-x La3Zr2-x Ta x O12 system. In the Al-doped system of Li7-x-3y Al y La3Zr2-x Ta x O12, the tetragonal phase was formed at x + 3y < 0.4. The border between the tetragonal and the cubic phases exists at Li6.6-z/2Al z /2La3Zr1.6+z Ta0.4-z O12. The tetragonal/cubic structure change corresponds to the order/disorder of lithium ions and is dependent on the cation content at the lithium sites. The ionic conductivity of the cubic compounds has a positive tendency with respect to the lithium content, whereas that of the tetragonal compounds is opposite. A high total ionic conductivity exceeding 5.0 × 10-4 S cm-1 at 25 °C was observed for Al-doped Li6.6-z/2Al z /2La3Zr1.6+z Ta0.4-z O12. The highest total conductivity of 1.03 × 10-3 S cm-1 at 25 °C with an activation energy of 0.35 eV was obtained at z = 0.275. Nuclear magnetic resonance spectroscopy revealed that Al3+ substitution decreases the diffusion of lithium ions in the structure. The high total conductivity of Al-doped Li6.6-z/2Al z /2La3Zr1.6+z Ta0.4-z O12may be due to the enhancement of lithium diffusion at the grain boundaries. This work was partly supported by the Japan Science and Technology Agency (JST) under the project “Advanced Low Carbon Technology Research and Development Program, Specially Promoted Research for Innovative Next Generation Batteries (ALCA Spring)”. [1] K.H. Kim, Y. Iriyama, K. Yamamoto, S. Kumazaki, T. Asaka, K. Tanabe, C.A.J Fisher, T. Hirayama, R. Murugan and Z. Ogumi, J. Power Sources, 2011, 196, 764. [2] K. Ishiguro, H. Nemori, S. Sumahiro, Y. Nakata, R. Sudo, M. Matsui, Y. Takeda, O. Yamamoto and N. Imanishi, J. Electrochem. Soc., 161(5)(2014) A668. [3] R. Murugan, V. Thangadurai and W. Weppner, Angew. Chem. Int. Ed., 46(2007) 7778. [4] Y. Wang and W. Lai, Electrochem. Solid-State lett., 15 (2012) A68.

Improved ligand geometries in crystallographic refinement using AFITT in PHENIX.

Modern crystal structure refinement programs rely on geometry restraints to overcome the challenge of a low data-to-parameter ratio. While the classical Engh and Huber restraints work well for standard amino-acid residues, the chemical complexity of small-molecule ligands presents a particular challenge. Most current approaches either limit ligand restraints to those that can be readily described in the Crystallographic Information File (CIF) format, thus sacrificing chemical flexibility and energetic accuracy, or they employ protocols that substantially lengthen the refinement time, potentially hindering rapid automated refinement workflows. PHENIX-AFITT refinement uses a full molecular-mechanics force field for user-selected small-molecule ligands during refinement, eliminating the potentially difficult problem of finding or generating high-quality geometry restraints. It is fully integrated with a standard refinement protocol and requires practically no additional steps from the user, making it ideal for high-throughput workflows. PHENIX-AFITT refinements also handle multiple ligands in a single model, alternate conformations and covalently bound ligands. Here, the results of combining AFITT and the PHENIX software suite on a data set of 189 protein-ligand PDB structures are presented. Refinements using PHENIX-AFITT significantly reduce ligand conformational energy and lead to improved geometries without detriment to the fit to the experimental data. For the data presented, PHENIX-AFITT refinements result in more chemically accurate models for small-molecule ligands.

Refinement of cryo-EM structures using scattering factors of charged atoms

This paper reports a suitable treatment of electron scattering factors of charged atoms for refinement of atomic models against cryo-electron microscopy (cryo-EM) maps. The ScatCurve package developed here supports various curve models for parameterization of scattering factors and the parameter tables can be implemented in major refinement programs in structural biology. Partial charge values of charged amino acids in crystal structures were changed in small steps for refinement of the atomic models against electron diffraction data from three-dimensional crystals. By exploring a range of partial charges, the authors found the electrostatic setting that produces atomic models with improved statistics and better reflects experimental data. Structure refinement for single-particle analysis also benefits from the more accurate analysis and the programs could find wide use for model refinement against cryo-EM maps.

Adaptive simulations of detonation propagation in 90-degree bent tubes

The open-code adaptive mesh refinement program AMROC was adopted to conduct numerical simulations of detonation propagation in 90° bent tubes. Propagation modes in bent tubes, the mechanism of detonation restored to stable propagation and effects of curvature radius on detonation restoration were explored in depth. Results indicate that with the increase of initial pressure and inner wall curvature radius, detonation propagation undergoes a transition from the unstable mode to the transition mode, and finally the stable mode. The critical conditions for mode transition among the unstable mode, the transition mode and the stable mode are r0/λ = 13.7 and r0/λ = 22.3, respectively, where λ is the cellular width. In the unstable and transition modes, when the detonation crosses through the bent section, the detonation structure is destroyed. However, the generated Mach reflection can induce the formation of new transverse waves to realize re-initiation and the collision between two triple points can enhance the strength of the detonation gradually, which can cooperatively promote detonation restoration to self-sustained propagation. The curvature radius not only has an influence on the formation of the transverse wave, but also makes an impact on the position where the triple point of Mach reflection collides on the outer wall. The colliding position has an effect on collisions among triple points, which can influence detonation restoration eventually.

Refinance and Mortgage Default: A Regression Discontinuity Analysis of HARP’s Impact on Default Rates

This paper examines the impact of refinancing on mortgage defaults based on an empirical investigation of the Home Affordable Refinance Program (HARP). We study a unique dataset from Freddie Mac which includes loans funded right before and after the HARP eligibility cutoff date, an exogenous event. Using a Fuzzy Regression Discontinuity Design method, we show that receiving a HARP refinance decreases the expected monthly default rate by about 48–62 percent using different bandwidth specifications.

Comment on "Structural dynamics of cisplatin binding to histidine in a protein" [Struct. Dyn. 1, 034701 (2014)

Comment on "Structural dynamics of cisplatin binding to histidine in a protein" [Struct. Dyn. 1, 034701 (2014)

EFFECT OF EXTERNAL ENVIRONMENT ORGANIZATION AND APPLICATION OF TOTAL QUALITY MANAGEMENT (TQM) AND PERFORMANCE OF THE COMPANY AND ITS EFFECT ON COMPETITIVE ADVANTAGE IN PTISM BOGASARI FLOURMILLS, JAKARTA

This research aimed to discover the impact of external environment and Total Quality Management implementation on company performance in order to create competitive advantage in PT. ISM Bogasari Flourmills. This research is an associative explanatory research with quantitative method. The data sources used are primary data and secondary data. The primary data collected by spreading 122 questionnaires to employees of PT. ISM Bogasari on chief officers level, assistant manager level, and manager level. Sampling method used is Proportionable Stratified Random Sampling. The result showed that external environment with indicator of complexity, dynamics and environment carrying capacity, has positive and significant impact on company’s performance. Total Quality Management implementation with indicators of costumer focus, continuous refinement and staff training program, brings positive and significant impact on company’s performance. The company’s performance with its indicators of efficiency, effectiveness, and adaptability, has positive and significant impact on the creation of competitive advantage. The Research also proved that external environment and Total Quality Management Implementation directly affect the creation of competitive advantage.&#x0D; &#x0D; &#x0D; &#x0D; Keywords: External environment, Total Quality Management implementation, company’s performance, and competitive advantage&#x0D; &#x0D;