Role Of Structural Modifications Research Articles

Mammalian Diaphanous1 signalling in neurovascular complications of diabetes.

Over the past few decades, diabetes gradually has become one of the top non-communicable disorders, affecting 476.0 million in 2017 and is predicted to reach 570.9 million people in 2025. It is estimated that 70 to 100% of all diabetic patients will develop some if not all, diabetic complications over the course of the disease. Despite different symptoms, mechanisms underlying the development of diabetic complications are similar, likely stemming from deficits in both neuronal and vascular components supplying hyperglycaemia-susceptible tissues and organs. Diaph1, protein diaphanous homolog 1, although mainly known for its regulatory role in structural modification of actin and related cytoskeleton proteins, in recent years attracted research attention as a cytoplasmic partner of the receptor of advanced glycation end-products (RAGE) a signal transduction receptor, whose activation triggers an increase in proinflammatory molecules, oxidative stressors and cytokines in diabetes and its related complications. Both Diaph1 and RAGE are also a part of the RhoA signalling cascade, playing a significant role in the development of neurovascular disturbances underlying diabetes-related complications. In this review, based on the existing knowledge as well as compelling findings from our past and present studies, we address the role of Diaph1 signalling in metabolic stress and neurovascular degeneration in diabetic complications. In light of the most recent developments in biochemical, genomic and transcriptomic research, we describe current theories on the aetiology of diabetes complications, highlighting the function of the Diaph1 signalling system and its role in diabetes pathophysiology.

Excitation Wavelength and Concentration Dependent Photophysical behaviour of Dipolar Molecular rotors in Solution: Role of Structural Modification

The present work demonstrates that the twisted intramolecular charge transfer (TICT) and Intramolecular charge transfer (ICT) process can be achieved by structural modification of a molecule. The DMMC (2-(4-(dimethylamino)benzylidene)malononitrile) and DMDC (2-(4-(dimethylamino)benzylidene)malononitrile) exhibit TICT and ICT state respectively via structural modification at the ground state. Solvent-dependent fluorescence enhancement of these molecules is monitored by comparing the relative intensity of locally excited (LE) and ICT emission band from excitation wavelength and concentration-dependent study.Both molecules display the ICT emission process at excited state depending upon excitation wavelength and concentration in solution. Interestingly, aggregation behaviour is also observed during excitation wavelength and concentration-dependent study in H2O. Solvent and excitation wavelength-dependent quenching and enhancement of fluorescence properties are also observed. Dipolar state and molecular orientation may play an important role in excitation and concentration-dependent fluorescence process in solution.

Sn doping role in structural modifications and electrochemical performance of Co(OH)2 nanorods for supercapacitors applications

Herein, pristine and Sn–Co(OH)2 nanorods are prepared via hydrothermal method and pseudocapacitive properties are evaluated. The synthesized nanostructures are characterized by various sophisticated techniques including x-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), Brunauer–Emmett–Teller (BET) analysis, transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The SEM analysis discloses the structural modification of Co(OH)2 from nanoparticles to nanorods. Additionally, the presence of Sn in Co(OH)2 significantly influence the electrochemical active surface area which enhances the electrochemical properties as measured through cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). The SnCo-4 sample indicates high surface area (93.1 m2/g), superior performance with specific capacitance of 1441.8 F/g at 1 A/g and remarkable stability of 84.3 % retention after 5000 GCD cycles. The pseudocapacitive nature (b = 0.799) is observed to increases with scan rate (i.e. 59.1 % at 75 mV/s). This higher performance is mainly due to greater charge transportation and conductivity associated with nanorod morphology and Sn ion. These parameters disclosed that the prepared samples have great potential to be used against energy crisis.

The use of polymorphic state modifiers in solid lipid microparticles: The role of structural modifications on drug release performance

This study investigates the correlation between the structural and release properties of solid lipid microparticles (MPs) of tristearin containing 5 % w/w of four different liquid additives used as crystal modifiers: isopropyl myristate (IM), ethyl oleate (EO), oleic acid (OA) and medium chain triglycerides (MCT). All additives accelerated the conversion of the unstable α-form of tristearin, formed after the MPs manufacturing, to the stable β-polymorph and the transformation was completed within 24 h (for IM and EO) or 48 h (for OA and MCT). The kinetic of polymorphic transition at 25 °C was investigated by simultaneous synchrotron SAXS/WAXS and DSC analysis after melting and subsequent cooling of the lipid mixture. After crystallization in the α-phase, additives accelerate the solid-solid phase transformation to β-tristearin. SAXS data showed that two types of structural modifications occurred on MPs during storage: compaction of the crystal packing (slight decrease in lamellar thickness) and crystal growth (increased number of stacked lipid lamellae). The release behavior of a model hydrophilic drug (caffeine) at two different amounts (15 % and 30 %) from MPs was studied in water and biorelevant media simulated the gastric and intestinal environment. It was particularly significant that the introduction of IM, EO and MCT were able to prolong the drug release in water, passing from a diffusion-based Higuchi kinetics to a perfect zero-order kinetic. Moreover, the overall release profiles were higher in biorelevant media, where erosion/digestion of MPs was observed. After 6 months, a moderate but statistically significant change in release profile was observed for the MPs with IM and EO, which can be correlated with the time-dependent structural alterations (i.e. larger average crystallite size) of these formulations; while MPs with OA or MCT displayed stable release profiles. These findings help to understand the correlation between release behavior, polymorphism and supramolecular‐level structural modification of lipid formulations containing crystal modifiers.

Tungsten doping role in structural modification and boosting electrochemical efficiency of Co(OH)2 dandelion assemblies

Globally increasing energy demands and the drastic climate changes are pursuing cost-effective and environmental friendly energy storage option i.e. supercapacitors. Tungsten (W) doping in Co(OH)2 has played an effective role in morphology changes along with improving its super capacitive properties. The 5 % W-doped Co(OH)2 revealed perfectly dandelion assemblies having size range 3–4 µm and emerging wires with ∼10 nm diameter. These dandelion assemblies exhibited pseudocapacitive behavior and excellent specific capacitance 1000 Fg−1 at 1Ag−1 and 1051 Fg−1 at 5mVs−1 which is more than twice as compared to pristine Co(OH)2. Power law (b = 0.71) exhibited capacitive nature of 5 % W-doped Co(OH)2. High cyclic stability with 92 % charge retention have been achieved for 5000 cycles. This improved electrochemical performance is attributed to the high surface area with numerous active sites, amazing Faradaic redox reactions and excellent charge transfer rate. Hence, 5 % W-Co(OH)2 dandelion assemblies are promising electrode materials for efficient supercapacitors.

Tailoring triple charge (O2−/H+/e−) conducting nature of Fe-based lanthanum doped samarium oxides for ceramic fuel cells (CFCs)

Lattice defects in rare earth (RE) doped single-phase semiconductor materials play a key role in structural modifications and physicochemical characteristics, resulting to enhance the ionic conductivity. In this work, we synthesized lanthanum doped samarium oxide with different mole ratios and applied it as a ceramics membrane fuel cell device to enable high peak power density (PPD) at low operational temperatures (520–400 °C). The samples are capable of triple charge H+/O2−/e− conduction and enhance the catalytic function of the cell in terms of HOR and ORR kinetics by producing lattice defects. The fabricated Sm1.5La1.5Fe5O12 (2-SLFO) fuel cell device exhibits a high OCV of 1.13 V with a maximum PPD of 864.26 mW/cm2 at 520 °C. Durability measurement verifies that 2-SLFO-based fuel cell device can be worked for 60 h under fuel cell conditions (H2/air) at 520 °C. The first principle calculations using density functional theory (DFT) demonstrate that the higher oxygen vacancy concentration in the 2-SLFO sample may cause to the higher charge-transfer kinetics, subsequent in the enhancement of ions transportation of the fabricated fuel cell device.

From Electric Doping Control to Thermal Defect Nucleation in Perovskites

AbstractSimultaneous optical microscopy and electric transport measurements on La0.7Sr0.3MnO3 nanobridges, grown on SrTiO3 (STO), show direct evidence of directional oxygen vacancy migration under large voltage bias. Comparative study on discontinuous structures, with voltages applied across a micron‐scale gap, demonstrates that high electric fields induce electrolytic modifications confined to the anode. Extensive electromigration is shown to induce the formation of linear surface scars on the STO substrate, following well defined crystallographic directions. The reproducible triggering of these surface dislocations is demonstrated, unveiling their thermal rather than electrical origin and it is shown that they do not represent electroformed conduction channels. High‐resolution scanning transmission electron microscopy imaging reveals that the scars correspond to nanometer scale steps caused by (101) gliding planes in the STO caused by the proliferation of edge dislocations and local lattice expansion. These findings shed light on selective electrically‐controlled atom migration and its role in structural modification of functional oxides, opening a unique avenue for ionotronic device design.

Oxygen-vacancy-induced O2 activation and electron-hole migration enhance photothermal catalytic toluene oxidation

The rapid elimination of volatile organic compounds and the intermediate analysis with efficient photothermal catalysis are of great significance to the environment. Oxygen vacancies (Vo) play a crucial role in structural modification and performance improvement of heterogeneous catalysts. Accordingly, here, abundant Vo sites are introduced into Co 3 O 4 /TiO 2 composite via treatment under H 2 and Ar flow at 200°C, and the photothermal catalytic performance of toluene is significantly improved. The molecular oxygen (O 2 ) adsorbed by Vo is activated to form reactive oxygen species for deep oxidation of toluene. Vo generated on the unilateral side in Co 3 O 4 /TiO 2 heterojunctions serves to capture electrons and break the dynamic balance of electron-hole pairs. The excited electrons are trapped by Vo, and the direct recombination of electron-hole pairs is inhibited, thus promoting the photochemical process. Moreover, the photothermal synergy effect and the relationship between Vo evolution and intermediates transformation mechanism are systematically studied. • The oxygen-vacancy-induced O 2 adsorption and activation mechanism in photothermal catalysis is studied • Oxygen-vacancy-trapped electrons inhibit electron-hole pair recombination • Oxygen vacancies promote rapid photothermal oxidation of toluene and intermediates Oxygen vacancies are known to influence the performance of heterogeneous catalysts. Herein, Yang et al. show that oxygen vacancies in Co 3 O 4 /TiO 2 induce the activation of O 2 and migration of electron holes, with light-generated carriers promoting the generation of active radicals to catalyze the oxidation of toluene.

Intercalated Iron Chalcogenides: Phase Separation Phenomena and Superconducting Properties.

Organic molecule-intercalated layered iron-based monochalcogenides are presently the subject of intense research studies due to the linkage of their fascinating magnetic and superconducting properties to the chemical nature of guests present in the structure. Iron chalcogenides have the ability to host various organic species (i.e., solvates of alkali metals and the selected Lewis bases or long-chain alkylammonium cations) between the weakly bound inorganic layers, which opens up the possibility for fine tuning the magnetic and electrical properties of the intercalated phases by controlling both the doping level and the type/shape and orientation of the organic molecules. In recent years, significant progress has been made in the field of intercalation chemistry, expanding the gallery of intercalated superconductors with new hybrid inorganic–organic phases characterized by transition temperatures to a superconducting state as high as 46 K. A typical synthetic approach involves the low-temperature intercalation of layered precursors in the presence of liquid amines, and other methods, such as electrochemical intercalation, intercalant or ion exchange, and direct solvothermal growths from anhydrous amine-based media, are also being developed. Large organic guests, while entering a layered structure on intercalation, push off the inorganic slabs and modify the geometry of their internal building blocks (edge-sharing iron chalcogenide tetrahedrons) through chemical pressure. The chemical nature and orientation of organic molecules between the inorganic layers play an important role in structural modification and may serve as a tool for the alteration of the superconducting properties. A variety of donor species well-matched with the selected alkali metals enables the adjustment of electron doping in a host structure offering a broad range of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed, involving the influence of the chemical and electrochemical nature of intercalating species on the crystal structure and critical issues related to the superconducting properties of the hybrid inorganic–organic phases. Mutual relations between the host and organic guests lead to a specific ordering of molecular species between the host layers, and their effect on the electronic structure of the host will be also argued. A brief description of a critical assessment of the association of the most effective chemical and electrochemical methods, which lead to the preparation of nanosized/microsized powders and single crystals of molecularly intercalated phases, with the ease of preparation of phase pure materials, crystal sizes, and the morphology of final products is given together with a discussion of the stability of the intercalated materials connected with the volatility of organic solvents and a possible degradation of host materials.

An Improved Protocol for the Virtual Screening Discovery of Novel Histone Deacetylase Inhibitors.

Histone deacetylases (HDACs) are enzymes that play a key role in structural modification and gene expression. The overexpression of HDAC is associated with cancer, and thus inhibiting the enzyme could be an efficient cancer therapy. To discover new HDAC inhibitors (HDACis), we proposed an improved protocol combining a hierarchical pharmacophore search, molecular docking, and molecular dynamic simulations. The test results showed that the improved screening protocol effectively reduced the false-positive rates of drug-like chemicals. Based on the protocol, we obtained 16 hit compounds as potential HDACis from the Life Chemicals database. Enzyme inhibition experiments showed that two of the hit chemical compounds had HDAC-inhibitory effects. In vitro assays showed that Z165155756 could selectively inhibit the proliferation of cancer cells and specifically promoted apoptosis and induced G1/S phase arrest in A2780 cells. It may have potential therapeutic effects in ovarian cancer and is worthy of further investigation.

Pressure-Induced Polymorphic, Optical, and Electronic Transitions of Formamidinium Lead Iodide Perovskite.

Formamidinium lead iodide (FAPbI3) perovskite as a superior solar cell material was investigated in two polymorphs at high pressures using in situ synchrotron X-ray diffraction, FTIR spectroscopy, photoluminescence (PL) spectroscopy, electrical conductivity (EC) measurements, and ab initio calculations. We identified two new structures (i.e., Imm2 and Immm) for α-FAPbI3 but only a structural distortion (in C2/c) for δ-FAPbI3 upon compression. A pressure-enhanced hydrogen bond plays a prominent role in structural modifications, as corroborated by FTIR spectroscopy. PL measurements and calculations consistently show the structure and pressure dependences of the band gap energies. Finally, EC measurements reveal drastically different transport properties of α- and δ-FAPbI3 at low pressures but a common trend to metallic states at high pressures. All of these observations suggest strongly contrasting structural stabilities and pressure-tuned optoelectric properties of the two FAPbI3 polymorphs.

THE RELATIONSHIP BETWEEN HOFSTEDE ORGANIZATIONAL CULTURE AND EMPLOYEES JOB BURNOUT IN HOSPITALS OF TEHRAN UNIVERSITY OF MEDICAL SCIENCES 2014-2015.

Objective:Organizational culture plays a supportive role in modification of structure and implementation of new management systems. So, the management of organizational culture with cultural elements recognition plays an important role in improving the efficacy and effectiveness of the organization. On the other hand, the health sector requires healthy and motivated practitioners and staff to achieve these goals. Job burnout as a response to environmental stressors causes some changes in attitude and behavior towards work and work environment, and factors such as organizational culture effect on it. This study aimed to clarify the relationship between organizational culture and employee’s burnout.Material and Methods:This is a descriptive and cross-sectional study. The study population included all clinical staff (physicians and nurses) and nonclinical (administrative and financial) in hospitals affiliated to Tehran University of Medical Sciences in 2014-2015. Among them, 387 participants were selected using simple stratified random sampling. In order to collect the required data, the Maslach Burnout Inventory (1981) and Hofstede’s organizational cultural questionnaire (1988) were used. Also Cronbach’s alpha obtained 0.836 and 0.913 for them, respectively. In order to analyze the data, the Kolmogorov-Smirnov test, multiple regression, independent t-test and binomial test were performed using SPSS 20.Results:Results showed that organizational culture in studied population were masculine, collectivism with high uncertainty avoidance and relatively equitable power distance. Mean score for emotional exhaustion was (31.4) and most of participants 315 (40.6%) had average emotional exhaustion. Mean score for depersonalization was (21.16) and most of participants 315 (82.1%) had high depersonalization. Mean score for personal accomplishment was (30.02) and most of participants 280 (73.2%) had high personal accomplishment. Multiple correlation coefficient showed that there is a significant relationship between the components of organizational culture including masculinity/femininity, individualism/collectivism, uncertainty avoidance and power distance with job burnout (r=0.305, p>0.001). R2 also showed that 9.3 percent of the variance of job burnout is related to the mentioned factors.Conclusion:The overall result is that some staff health issues rooted in their culture; so, the organizational culture assessment by hospital managers to plan and goals achievement is essential. If necessary, improving organizational culture, creating a healthy environment, enhancing tolerance and individual adjustment and stress control can help to reduce staff burnout.

AtTRB1–3 Mediates Structural Changes in AtPOT1b to Hold ssDNA

POT from Arabidopsis thaliana is a member of shelterin complex and belongs to Telo_bind protein family. Three homologs are reported, namely, AtPOT1a, AtPOT1b, and AtPOT1c, where AtPOT1b is involved in genomic stability and chromosome end protection by providing necessary grip to G-rich region of telomeric DNA for telomerase assembly. Telomeric binding factors (TRB1–3) physically interact with POT with no known functionality. In this work attempt has been made to elucidate the reason behind the interaction by analyzing molecular docking interaction between AtPOT1b and AtTRB1–3, which yielded potential residues, which could play essential role in structural modification. 3 ns molecular simulation helped to look into structural stability and conformational dynamics portraying domain movements. AtTRB’s interaction with AtPOT1b provoked structural changes in AtPOT1b, thereby increasing the affinity for single strand DNA (ssDNA) as compared to double strand DNA (dsDNA). Although the obtained results require experimental evidence they can act as a guide in tracing the functions in other organisms. The information provided in this paper would be helpful in understanding functions of TRB1–3 with respect to genomic stability.

Role of structural modification on the electrical properties of poly(ethylene terephthalate) irradiated with 90‐MeV carbon ion beam

AbstractThin films of poly(ethylene terephthalate) (PET) having a thickness of 100 μm were exposed to different ion fluence of swift heavy ions of carbon in the range of 5 × 1011 – 5 × 1013 ions/cm2. The effect of ion beam on structural and electrical modification has been studied by UV/vis, FTIR, X‐ray diffraction (XRD), Differential Scanning Calorimetery (DSC), and AC electrical measurement techniques. On irradiation, a shift in absorption wavelength toward the red end of spectrum with increase of ion fluence was observed. The intensity of crystalline IR bands and main diffraction peak in XRD pattern were found to decrease with increase in ion fluence. It indicates the loss of crystallinity induced by ion‐beam irradiation. The crystallite size was found to increase on irradiation. The melting temperature (Tm) of PET films increased at a low ion dose (5.0 × 1012 ions/cm2), while it decreased at higher ion fluence (50.0 × 1012 ions/cm2). The dielectric constant (ε′) of PET films was increased with increase of ion fluence. The modifications brought about in the dielectric constant are correlated with chemical and molecular structural changes occurring on irradiation. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.

Irradiation-Induced Magnetism in Carbon Nanostructures

Nitrogen (15N) and carbon (12C) ion implantations with implant energy of 100 keV for different doses were performed on nanosized diamond (ND) particles. Magnetic measurements on the doped ND show ferromagnetic hysteresis behavior at room temperature. The saturation magnetization (M(s)) in the case of 15N implanted samples was found to be higher compared to the 12C implanted samples for dose sizes greater than 10(14) cm(-2). The role of structural modification or defects along with the carbon-nitrogen (C-N) bonding states for the observed enhanced ferromagnetic ordering in 15N doped samples is explained on the basis of x-ray photoelectron spectroscopy measurements.

Cytotoxic and genotoxic effects of tert-butyl hydroperoxide on Chinese hamster B14 cells

The organic hydroperoxide, tert-butyl hydroperoxide (t-BHP), is a useful model compound to study mechanisms of oxidative cell injury. In the present work, we examined the features of the interactions of this oxidant with Chinese hamster B14 cells. The aim of our study was to reveal a possible role of structural modifications in membranes and loss of DNA integrity in t-BHP-induced cell injury and death. The tert-butyl hydroperoxide treatment (100–1000μM, 37°C for 1h) did not decrease cell viability (as measured by cell-specific functional activity with an MTT test), but completely prevented cell growth. We observed intracellular reduced glutathione (GSH) oxidation and total glutathione (GSH+GSSG) depletion, a slight increase in the level of lipid-peroxidation products, an enhancement of membrane fluidity, intracellular potassium leakage and a significant decrease of membrane potential. At oxidant concentrations of 100–1500μM, a significant damage to DNA integrity was observed as revealed by the Comet assay. The inhibition of cell proliferation (cell-growth arrest) may be explained by genotoxicity of t-BHP, by disturbance of the cellular redox-equilibrium (GSH oxidation) and by structural membrane modifications, which result in ion-non-selective pore formation. The disturbance in passive membrane permeability and the DNA damage may be the most dramatic cell impairments induced by t-BHP treatment. The presence of another oxidant, hypochlorous acid (HOCl), completely prevented t-BHP-induced DNA strand breaks, perhaps due to extracellular oxidation of t-BHP by HOCl.

Characterization of bovine serum albumin epitopes and their role in allergic reactions.

This review provides updated information on conformational and sequential epitopes identified in bovine serum albumin (BSA) and summarizes available data about the role of structural modifications on BSA antigenicity/allergenicity. Data on beef allergy and BSA antigenicity are reported, with reference both to the basic literature and to clinical results obtained by our group. BSA is an important allergen involved in milk and beef allergy. The presence of conformational epitopes has been suggested by indirect evidence, while at least one sequential epitope has been experimentally identified. The role of structural modifications on BSA antigenicity is discussed as well as the increased tolerance observed in allergic subjects consuming beef as strained (homogenized) and freeze-dried derivatives. Study of the molecular characteristics of a known major allergen allows the identification of technological processes that may be capable of improving the tolerance of allergic subjects to a specific food. Even though any hoped for reduced allergenicity must be verified under medical supervision, the use of new products could obviate the need to avoid important foods such as meat in childhood.

Novel 2‐phosphabicyclo[2.2.2]oct‐5‐ene derivatives and their use in phosphinylations

AbstractThe [4 + 2] cycloaddition of the double‐bond isomers (A and B) of dihydrophosphinine oxide 1 afforded novel phosphabicyclo[2.2.2]oct‐5‐ene derivates (2–4), formation of which was justified by PM3 semiempirical calculations. The compounds of dimer type (2–4) were utilized in the UV light‐mediated fragmentation‐related phosphinylation of nucleophiles, especially in that of alcohols. To explore the role of structural modifications on the fragmentation ability, disulfide 5, phosphabicyclooctane 7 obtained by the hydrogenation of 2, and the adduct of dihydrophosphinine oxide 1 with benzoquinone (7) were also synthesized and tested in fragmentation. © 2004 Wiley Periodicals, Inc. Heteroatom Chem 15:97–106, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10221

Temperature rising elution fractionation, infra red and rheology study on gamma irradiated HMSPP

It is well known that polypropylene undergoes simultaneous crosslinking and degradation under irradiation. However, there are speculations regarding the formation of branching under special conditions. It is also well known that the melt-strength property of a polymer increases with molecular weight and with long-chain branching due to the increase in the entanglement level. This study was a contribution to the understanding of the following points: the role of molecular weight, the role of structural modifications on nucleation properties; the structural changes on polypropylene. The results showed that degradation was the major reaction in the initial step of irradiation, however, the largely modified molecules concentrated in the high molecular weight fraction. The results also confirm that the branching formation is likely to occur.

Effects of Dimethyl Sulfoxide and Hypoxic Cell Radiosensitizers on the Radiation Response of the KHT Murine Tumor in Vivo

Previous studies have indicated the effectiveness of the nitroimidazole derivatives metronidazole and Ro 07-0582 in specifically sensitizing the hypoxic cell fraction of solid tumors to single doses of ionizing radiation. A number of structural analogs of these compounds are only slightly water soluble but dissolve readily in dimethyl sulfoxide (DMSO). To determine the feasibility of testing such analogs in DMSO, the above compounds and a nitropyrrole were dissolved in DMSO and investigated using the KHT fibrosarcoma in C3H mice. Although DMSO by itself increases the D0 of the chronically hypoxic cells in the tumor, the addition of a known sensitizer results in sensitization relative to the DMSO hypoxic level which is similar to that observed for the drug in aqueous solution. This indicates that in vivo studies of structural analogs having low water solubility are possible, thus allowing a more comprehensive study to be made of the role of structural modification on the ability of compounds to act as radi...