Atomic Charge Distribution Research Articles

Investigation on structural, spectroscopic, DFT, biological activity and molecular docking simulation of essential oil Gamma-Terpinene

Density functional theory (DFT) quantum chemical computations were used to explore the structural and spectroscopic characteristics of the Gamma terpinene molecule in this study. The inhibitory nature of the title chemical was revealed via molecular docking research. The optimization was conducted out through the DFT/B3LYP approach with the basis set 6-311++G(d,p). Molecular docking research was used to assess the anticancer activity of the Gamma terpinene molecule. The vibrational frequencies were allocated and compared to the empirically measured vibrational frequencies using the optimized molecular structure. The ultraviolet-visible spectrum was modeled and experimentally validated. Simulated computations of the molecular electrostatic potential surface were also performed to analyze the reactive behavior of the Gamma terpinene molecule. The stability and molecular reactivity of the molecule were computed using the HOMO-LUMO energies, energy gap, chemical potential (μ), electronegativity (χ), hardness (η), and softness (S) values. Natural bond orbital analysis has been used to obtain the molecule's second order perturbation energy E(2) values, which show the bioactivity of the Gamma terpinene molecule. The molecule's reactive site is confirmed by the Mulliken atomic charge distribution and total electron density plotted with the molecular electrostatic potential surface analysis. The in vitro investigation through disc diffusion method was used to assess gamma-terpinene's antibacterial and antifungal activity, while in silico analysis through molecular docking and pharmacokinetic evaluation was used to assess its anti-cancer activity and drug-likeness property. In anti-bacterial and anti-fungal analysis zones of clearance was observed at different concentrations and the highest binding affinity was observed against the breast cancer target protein ERα with a docking score of -6.6Kcal/mol.

Synthesis, single crystal X-ray, DFT, Hirshfeld surface and molecular docking studies of 9-(2,4-dichlorophenyl)-4a-hydroxy-tetramethyl-octahydro-1H-xanthene-1,8(2H)-dione

The synthesis and crystal structures of a 9-(2,4-dichlorophenyl)-4a-hydroxy-tetramethyl-octahydro-1H-xanthene-1,8(2H)-dione are described (DCX). Single crystal X-ray diffraction was used to investigate the crystal, and the most stable optimised structure was identified using the B3LYP/6-311++G(d,p) basis set, followed by FTIR and NMR analysis. The titled molecule has been the subject of theoretical and experimental research (DCX). The optimal structure of the investigated chemical matches the results of the X-ray study. In addition, TD-DFT analysis was used to offer more light on the manner in which the electronic transitions determined in the UV–Vis spectra were calculated. The compound's Hirshfeld surface analyses were presented and debated. The Density Functional Theory (DFT) approach was used to accomplish the theoretical computations. Using the TD-DFT/6-311++G(d,p) approach, the estimated maximum wavelength (λ) absorbance and the band gap energy of DCX were derived for various solvents and compared to experimental results. For various solvents, chemical reactivity assessments, Molecular Electrostatic Potential (MEP) maps with surface area maps, and electron excitation investigations were performed. Aside from that, topological and atomic charge distribution analyses were discussed. Individual vibrational modes were used to complete the vibrational assignments, which were then compared to experimental data. The docking studies were used to look into the interactions of the ligand (DCX) with appropriate protein targets, indicating that DCX could be used as an anticancer and anti-inflammmetry drug. As a result of the current research, DCX may be considered a possible therapeutic molecule. In terms of geometric and spectroscopic parameters, the experimental and theoretical results were very similar.

Effective electrostatic forces between two neutral surfaces with surface charge separation: valence asymmetry and dielectric constant heterogeneity

Based on CDFT calculations, we study new features of surface electrostatic force (SEF) between two face-to-face overall neutral surfaces, each of which is comprised of atomic scale strip shape charge distribution and is immersed in +2:−1 electrolyte. Dielectric constant of near surface fluid is lower than that of distant fluid. Ion valence and dielectric constant heterogeneity effects are reflected in the following aspects. (i) For asymmetrical configuration of the strip shape charge distribution, if the coexistence bulk mole concentration is high like , one repulsion peak of the SEF appears at approximately two times the ion diameter and the peak height increases obviously with the ion valence and the strip shape domain width ; however, for low value, like , the ion valence almost does not cause any effect on the SEF shape and strength at small distances except that the higher valence ion causes a higher decaying rate of the SEF with the surface separation. (ii) For the case of the asymmetrical configuration and bivalent ion, strength of the small distance attractive SEF always reduces with the value, and is positively correlated with the value except when the value is high and the domain surface charge strength is low. (iii) The symmetrical strip shape charge distribution is an efficient way in inducing the attractive SEF in presence of bivalence ions even if the value is low down to ; the attraction strength is positively correlated with the value. (iv) The ion adsorption, playing a key role in influencing the SEF for the present overall neutral two-surface system, generally increases with the value, and far higher than that relevant to two similarly charged surfaces with equal value. (v) The lower surface fluid dielectric constant accords both the force and potential curves with new features like alternative mode of attraction and repulsion even in low bulk concentration, big strength in comparison with the average thermal energy, and large insensitivity to the surface charge distribution patterns and ion valence.

Synthesis, Spectroscopic Characterization, Molecular Docking and in Vitro Cytotoxicity Evaluation Studies on 6-Methoxy-8-Nitroquinoline Hydrogen Sulphate: A Novel Cervical Cancer Drug

The 6-Methoxy-8-nitroquinoline hydrogen sulfate (6M8NQHS) molecule has been studied using density functional theory (DFT) with thorough and accurate vibrational and spectroscopic investigations, as well as experimental validation. FT-IR, FT-Raman, and UV-Vis spectroscopy techniques were used to characterize the synthesized 6M8NQHS sample. The optimized molecular structure and harmonic vibrational frequencies of the molecule were calculated using DFT/B3LYP method with a LANL2DZ basis set using the Gaussian 09 program. The computed and experimental vibrational wavenumbers were assigned. The UV-Vis spectrum absorption spectrum of the molecule was observed in the liquid phase (acetone) and also simulated, which shows the π to π* and n to π* electronic transitions of the molecule. Frontier molecular orbital research reveals the molecule’s molecular reactivity and kinetic stability. The molecule’s reactive site is confirmed by the Mulliken atomic charge distribution and molecular electrostatic potential surface analysis. The bioactivity of the molecule was demonstrated by the natural bond orbital analysis. Molecular docking analysis confirms that the 6M8NQHS molecule inhibits the action of human p38a Mitogen-activated protein kinase 14, which is linked to cervical cancer. In addition, the MTT assay was used to determine the in vitro cytotoxicity of the 6M8NQHS molecule against human cervical cancer cell lines (ME180) and human breast cancer cell lines (MDA MB 231), demonstrating that the title molecule inhibits the cervical cancer cell lines more than breast cancer cell lines. As a result, the current research paves the way for the creation of new drugs to treat cervical cancer.

Design, Synthesis, Spectroscopic Characterization, Molecular Docking and Biological Evaluation of 9H-Carbazole Linked 4-Nitrophenol: A DFT Approach

The FT-IR and FT-Raman spectra of 3-(4-nitrophenoxy)-9,9a-dihydro-4aH-carbazole (9HCNP) molecule were recorded. The theoretical wavenumbers are in proper agreement with the observed results. The electronic properties, such as natural bond orbital study of the molecule, were confirmed using the inter/intra molecular interactions, molecular electrostatic potential, and Mulliken population analyses on the atomic charge distribution, performed by the Becke-3–Lee–Yang–Parr (CAM-B3LYP) method utilizing Gaussian 09 software. The oscillator strength of electronic transitions and energies of HOMO and LUMO molecular orbitals were carried out to evaluate the global chemical reactivity descriptors of 9HCNP. The molecular docking evaluation was carried out to evaluate the structure–activity relationship and the binding affinity of the molecule, which shows that the molecule can perform as an inhibitor of breast cancer-causing human topoisomerase-I and II-DNA receptors. The result of the conjugation was found to play a significant role in bioactivity and drug-likeliness properties, which can be supported by the molecular docking analysis of those compounds. In addition, the morphological changes in control and in vitro cytotoxicity of 9HCNP confirm the anticancer activity of 9HCNP against human breast cancer cell lines was assessed in 24-h tetrazolium-dye (MTT) cytotoxicity assays and also analyzed in terms of the role of reactive oxygen species (ROS) in cell life. Hence, the results show the in vitro anticancer activity of the molecule for the development of human breast cancer drugs.

Nitrogen-Containing Graphene for Electrochemical Sensing of Glucose

N-containing graphene was an excellent candidate for sensing and biosensing because of its comparable atomic radius with that of carbon and the formation of strong bonds. Its presence influenced the atomic charge distribution on the graphene scaffold, thereby enhancing the electrochemical activity. Here, nitrogen-containing graphene (N-graphene) prepared from papaya seeds was used to fabricate the electrode for the electrochemical oxidation of glucose using cyclic voltammetry and amperometry studies. The fabricated electrode showed a good response (6s) towards electrochemical oxidation of glucose with a linear range of 50-800 mg/L (R2=0.99369), the sensitivity of ~ 10.888 μAM−1cm−2 along with a detection limit of 0.9 μM. It efficiently determined the glucose concentration in three real samples (apple juice, coco-cola, and honey), which were found to be 2.06%, 4.21%, and 41%, respectively. Moreover, the electrode exhibited an acceptable reproducibility (RSD 7.6%), and the stability was observed as 82..6% of the initial value up to 15 days.

Coordination of Ethylamine on Small Silver Clusters: Structural and Topological (ELF, QTAIM) Analyses.

Amine ligands are expected to drive the organization of metallic centers as well as the chemical reactivity of silver clusters early growing during the very first steps of the synthesis of silver nanoparticles via an organometallic route. Density functional theory (DFT) computational studies have been performed to characterize the structure, the atomic charge distribution, and the planar two-dimensional (2D)/three-dimensional (3D) relative stability of small-size silver clusters (Agn, 2 ≤ n ≤ 7), with or without an ethylamine (EA) ligand coordinated to the Ag clusters. The transition from 2D to 3D structures is shifted from n = 7 to 6 in the presence of one EA coordinating ligand, and it is explained from the analysis of the Ag-N and Ag-Ag bond energies. For fully EA saturated silver clusters (Agn-EAn), the effect on the 2D/3D transition is even more pronounced with a shift between n = 4 and 5. Subsequent electron localization function (ELF) and quantum theory of atoms in molecules (QTAIM) topological analyses allow for the fine characterization of the dative Ag-N and metallic Ag-Ag bonds, both in nature and in strength. Electron transfer from ethylamine to the coordinated silver atoms induces an increase of the polarization of the metallic core.

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

A Highly Efficient Sulfur Host Enabled by Nitrogen/Oxygen Dual‐Doped Honeycomb‐Like Carbon for Advanced Lithium–Sulfur Batteries

High energy density and long cycle life of lithium-sulfur (Li-S) batteries suffer from the shuttle/expansion effect. Sufficient sulfur storage space, local fixation of polysulfides, and outstanding electrical conductivity are crucial for a robust cathode host. Herein, a modified template method is proposed to synthesize a highly regular and uniform nitrogen/oxygen dual-doped honeycomb-like carbon as sulfur host (N/O-HC-S). The unique structure not only offers physical entrapment for polysulfides (LiPSs) but also provides chemical adsorption and catalytic conversion sites of polysulfides. In addition, this structure offers enough space for loading sulfur, and a regular space of nanometer size can effectively prevent sulfur particles from accumulating. As expected, the as-prepared N/O-HC900-S with high areal sulfur loading (7.4mg cm-2 ) shows a high areal specific capacity of 7.35 mAh cm-2 at 0.2 C. Theoretical calculations also reveal that the strong chemical immobilization and catalytic conversion of LiPSs attributed to the spin density and charge distribution of carbon atoms will be influenced by the neighbor nitrogen/oxygen dopants. This structure that provides cooperative chemical adsorption, high lithium ions flux, and catalytic conversion for LiPSs can offer a new strategy for constructing a polysulfide confinement structure to achieve robust Li-S batteries.

Structural, electronic properties (different solvents), chemical reactivity, ELF, LOL, spectroscopic insights, molecular docking and in vitro anticancer activity studies on methyl (4-nitro-1-imidazolyl)acetate

The theoretical and experimental investigations have been performed on the header composite Methyl (4-nitro-1-imidazolyl)acetate (M4NIA). The theoretical calculations were performed by employing the Density Functional Theory (D F T) technique. Potential energy scan (PES) analysis and the theoretical geometrical parameters were assessed and compared with related recorded values. Further, the computed maximum wavelength (λ) absorbance and the bandgap energy of M4NIA were obtained for various solvents were performed using the TD-DFT/MO62X method and related with recorded value. The molecular reactivity analyses and Electrostaticpotential (ESP) map with surface area map and electron excitation investigations for different solvents were evaluated. Besides, atomic charge distribution analysis and topological analyses were discussed. The vibrational assignments were accomplished on the PED of individual vibrational modes and compared with experimental values. The docking studies were considered to investigate the interactions between the ligand (M4NIA) with suitable protein targets, which designates that M4NIA can act as a novel inhibitor of anticancer agents. Also, in vitro (MTT assay) has been subjected to inspect the anticancer activity of M4NIA towards human cancer cell lines. Hence, the present investigations indicate that M4NIA could be regarded as a potential anticancer lead compound.

Electronic, spectroscopic, molecular docking and molecular dynamics studies of neutral and zwitterionic forms of 3, 4-dihydroxy-l-phenylalanine: A novel lung cancer drug

The 3, 4-dihydroxy-l-phenylalanine (L-DOPA) is used as an effective drug for the treatment of Parkinson's disease and also used as a precursor of many alkaloids. In the present study, the most stable optimized structures of l-DOPA in neutral and zwitterionic forms were predicted by the B3LYP functional method with cc-pVTZ basis set. The theoretical vibrational frequencies were assigned based on the potential energy distribution calculations using VEDA 4.0 and compared experimentally with the available FT-IR and Raman data. The lack of negative values in the calculated vibrational frequencies implies that the optimized geometries of the studied molecules are located at the local minima on the potential energy surfaces. The π→ π* and the n→ π* electronic transitions of the l-DOPA molecules were predicted from the theoretically simulated ultraviolet-visible spectra obtained in COSMO as a model of solvation. The frontier molecular orbitals are plotted, and the related molecular properties are calculated and discussed. The Mulliken atomic charge distribution calculations and the molecular electrostatic potential surfaces were simulated to confirm the reactive sites of the molecules under consideration. The natural bond orbital (NBO) analysis proves the bioactivity of each form of l-DOPA molecule. The molecular docking analysis reveals that the zwitterion l-DOPA molecule has a strong binding affinity towards the AKT targeted protein used in the treatment of lung cancer compared to the neutral l-DOPA molecule. The reliability of the docking results is validated from the data of the molecular dynamics simulations. Hence, the present study paves the way for designing the novel drugs for the treatment of lung cancer.

Comparative study on adsorption behaviour of the monolayer graphene, boron nitride and silicon carbide hetero-sheets towards carbon monoxide: Insights from first-principle studies

A comprehensive study on the sensitivity of graphene, boron nitride, silicon carbide and their in-plane hetero-sheets towards carbon monoxide (CO) was performed using first-principle density functional theory calculations. To rationalize the CO adsorption on pristine and hetero-sheets, molecular electrostatic potential contours, HOMO-LUMO distributions, the density of states plots, atomic charge distributions and quantum chemical descriptors were calculated. The optimized geometries showed that the CO molecule oriented itself at different angles with respect to sheets. A shift in the characteristic vibrational frequency of CO was observed through theoretically computed infra-red spectra. The maximum shift was observed for the GRA/SiC hetero-sheet. Charge analysis showed the partial charge transfer from the CO molecule to the adsorbent sheets. This was further confirmed by the HOMO-LUMO distributions of the interacting species. The reactivity descriptors calculated based on the HOMO-LUMO energies, molecular electrostatic potential contours and DOS plots showed that GRA/SiC hetero-structure exhibited better sensitivity towards CO than other sheets. The calculated adsorption energies, corrected for basis set superposition error, ranged from −3 to −10 kJ mol−1, confirming the physical nature of adsorption.

Conformational, spectroscopic, electronic and Molecular docking Studies on 2-methoxy-4-methyl-5-nitropyridine: A potential bioactive agent

The molecular geometry, vibrational bands, electronic properties and NMR spectra of 2 methoxy 4 methyl 5 nitropyridine (MMNP) were studied using density functional theory (DFT) calculations. The MMNP molecule was optimized using the DFT/B3LYP approach with the cc-pVTZ basis set to acquire the stable geometry. The potential energy distribution (PED) simulation was used to assign the obtained vibrational wavenumbers of the MMNP molecule. The chemical shift of 13C and 1H NMR spectrum was derived using the Gauge-Invariant-atomic orbital (GIAO) approach using DMSO solution and compared with the observed shifts. To investigate the electronic absorption spectral features of the MMNP molecule, the UV-Vis spectrum was simulated and observed. The hyperconjugation and intramolecular charge transfer were predicted using FMO and NBO analysis. Mulliken atomic charge distribution, Molecular Electrostatic potential (MEP) surface and the local reactivity analysis were used to spot out the reactive sites of the MMNP molecule. Moreover, the MMNP molecule acts as a potent inhibitor against bladder cancer so that the title molecule may be used in the drug designing for the treatment of bladder cancer.

The flexible Janus X2PAs (X = Si, Ge and Sn) monolayers with in-plane and out-of-plane piezoelectricity

The 2D piezoelectric materials have attracted growing attention due to their potential application in energy harvesters, strain sensors and active flexible electronics. Now, the challenge is to find flexible 2D material with piezoelectricity in both in-plane and out-of-plane. To address this challenge, this paper demonstrates the Janus X2PAs (X = Si, Ge and Sn) monolayers through density functional theory (DFT) calculation for the first time. The dynamical stability, stiffness and piezoelectric tensors of these monolayers are systematically investigated. The results show that these monolayers are stable and extremely flexible. The X2PAs monolayers exhibit piezoelectric effect in both in-plane and out-of-plane. Especially, among them, the Sn2PAs monolayer has the largest piezoelectric coefficient |d31| (1.42 pm/V) that is two times larger than the |d31| of group III–V buckled honeycomb (GaP, GaAs, InP and InAs) monolayers (0.40 ∼ 0.74 pm/V) and MoSO monolayer (0.7 pm/V). These facts are due to an inversion symmetry breaking (along the out-of-plane direction) in both atomic structures and charge distribution of X2PAs monolayers. The out-of-plane piezoelectric and flexible characters of these 2D Janus X2PAs monolayers could enhance their performance in multifunctional sensing and controlling of the nanodevices.

Activation of peroxymonosulfate by MnO2 with oxygen vacancies: Degradation of organic compounds by electron transfer nonradical mechanism

Recently, ecofriendly and low toxicity manganese-based materials are receiving increased attention for the activation of peroxymonosulfate (PMS). The surface property of manganese-based materials has strong effect on its activation performance. In this study, MnO2 with differing levels of oxygen vacancies (Vo-MnO2) were prepared and used for PMS activation. The effects of oxygen vacancies (Vo), activator dosage, PMS concentration, and the initial pH on para-chloroaniline (PCA) degradation were studied. In these studies, Vo-MnO2 showed good stability and reusability for PMS activation. In addition, a series of experiments revealed the PMS activation mechanism. Interestingly, •OH, SO4•- and 1O2 were not primarily responsible for PCA degradation. PCA was degraded by the reactive complex formed by PMS and Vo-MnO2. Based on the characterization results and DFT calculations, the introduction of Vo in MnO2 changed the charge distribution of Mn atoms and enhanced PMS adsorption. This is more favorable to form the reactive complex in electron transfer mechanism. Besides, Vo increases the Mn3+ content in MnO2, which enhances oxidation ability of reactive complex and the efficiency of electron transfer. The degradation efficiency of pollutants in the Vo-MnO2/PMS system has been improved significantly. This study highlights the pivotal roles of Vo in electron transfer mechanism and provides a new method for the practical application in wastewater treatment.

Free-Energy Profile Analysis of the Catalytic Reaction of Glycinamide Ribonucleotide Synthetase.

The second step in the de novo biosynthetic pathway of purine is catalyzed by PurD, which consumes an ATP molecule to produce glycinamide ribonucleotide (GAR) from glycine and phosphoribosylamine (PRA). PurD initially reacts with ATP to produce an intermediate, glycyl-phosphate, which then reacts with PRA to produce GAR. The structure of the glycyl-phosphate intermediate bound to PurD has not been determined. Therefore, the detailed reaction mechanism at the molecular level is unclear. Here, we developed a computational protocol to analyze the free-energy profile for the glycine phosphorylation process catalyzed by PurD, which examines the free-energy change along a minimum energy path based on a perturbation method combined with the quantum mechanics and molecular mechanics hybrid model. Further analysis revealed that during the formation of glycyl-phosphate, the partial atomic charge distribution within the substrate molecules was not localized according to the formal charges, but was delocalized overall, which contributed significantly to the interaction with the charged amino acid residues in the ATP-grasp domain of PurD.

Determining the charge distribution and the direction of bond cleavage with femtosecond anisotropic x-ray liquidography

Energy, structure, and charge are fundamental quantities characterizing a molecule. Whereas the energy flow and structure change in chemical reactions are experimentally characterized, determining the atomic charges of a molecule in solution has been elusive, even for a triatomic molecule such as triiodide ion, I3−. Moreover, it remains to be answered how the charge distribution is coupled to the molecular geometry; which I-I bond, if two I-I bonds are unequal, dissociates depending on the electronic state. Here, femtosecond anisotropic x-ray solution scattering allows us to provide the following answers in addition to the overall rich structural dynamics. The analysis unravels that the negative charge of I3− is highly localized on the terminal iodine atom forming the longer bond with the central iodine atom, and the shorter I-I bond dissociates in the excited state, whereas the longer one in the ground state. We anticipate that this work may open a new avenue for studying the atomic charge distribution of molecules in solution and taking advantage of orientational information in anisotropic scattering data for solution-phase structural dynamics.

DFT Study on the Substituent Effect of Anticancer Picoline-Diazido-Pt(IV) Compounds.

The geometric structure of azido Pt(IV) compounds containing picoline was calculated by using density functional theory(DFT) at the LSDA/SDD level. The ESP distribution shows the possible reaction sites of the compounds. In addition, the frequency calculation results assigned the infrared spectra of these compounds, and specified important stretching and bending vibrations. The HOMO-LUMO energy gaps of these compounds are also calculated to explain the charge transfer of the molecules. The distribution of Mulliken charges and natural atomic charges of these atoms is also calculated. Natural bond orbital(NBO) analysis explains the intramolecular interactions and their electron density.

Regulating Charge Distribution of Ru Atoms in Ruthenium Phosphide/Carbon Nitride/Carbon for Promoting Hydrogen Evolution Reaction

Regulating Charge Distribution of Ru Atoms in Ruthenium Phosphide/Carbon Nitride/Carbon for Promoting Hydrogen Evolution Reaction

Single crystal XRD and DFT investigation of 1,5-dimethyl-4-[(2-oxo-1,2-diphenylethylidene) amino]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one

The single crystal 1,5-dimethyl-4-[(2-oxo-1,2-diphenylethylidene) amine]-2-phenyl-1,2-dihydro-3H-pyrazol-3-one [DDAPDP] was designed to enhance luminescence property using benzil and 4-aminoantipyrine. DFT calculations of DDAPDP were done with Gaussian 16 W program employing hybrid functional B3LYP with 6–311++G (d,p) basis set for geometry optimization without symmetry constraints. The single crystal was studied based on theoretical aspects such as Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), Mullikan atomic charge and Molecular Electrostatic Potential (MEP) using density functional method. The experimental and theoretical spectral analysis of the single crystal system was investigated using FTIR, Raman, UV –visible, 1H NMR and 13C NMR techniques. Positive electrostatic potential regions dispersed throughout the rings and represent possible nucleophilic attack sites, whereas negative electrostatic potential regions are typically grouped around the CO group. Energy gap −3.776391 eV, confirmed by the estimated HOMO and LUMO energies. Natural bond orbital analysis (NBO) was used to assess the molecule's stability as a result of charge delocalization and hyper conjugation. Electron population of each atom was calculated by Mulliken atomic charge distribution analysis. The bacterium E. coli (Gram negative) and the organism S. aureus, together with a standard medication, were used to study and assess the compounds' antimicrobial activity in vitro, which reveals the antibacterial and antifungal activities of DDAPDP.