Single Ab Research Articles

Clinical implications of variations in anti-infliximab antibody levels in patients with inflammatory bowel disease

The aim of the study was to investigate variations in anti-infliximab (IFX) antibody (Ab) levels and clinical implications thereof in patients with inflammatory bowel disease (IBD). A retrospective, explorative, single-center study of patients with IBD who developed anti-IFX Ab and in whom anti-IFX Ab were reassessed. IFX was administered to 316 patients; anti-IFX Ab was determined in 180 patients and detected in 83 (46%). During ongoing IFX maintenance therapy, anti-IFX Ab disappeared at later reassessment in two-thirds of patients with clinical response after median 4 (3-5) infusions. In contrast, anti-IFX Ab persisted in all patients without clinical response. Anti-IFX Ab appeared pharmacologically active, as IFX levels were high when anti-IFX Ab disappeared (median 3.7 μg/mL, interquartile range [IQR] 2.8-5.5), while undetectable or low when anti-IFX Ab persisted (median 0 μg/mL, IQR 0-0). In 56 patients, anti-IFX Ab were assessed after IFX discontinuation. The proportion of patients with anti-IFX Ab gradually declined over time, with a few patients having anti-IFX Ab up to about 4 years after initial assessment. No variables were associated with anti-IFX Ab disappearance in multivariate analysis. Discontinuation of IFX is advisable in patients with inadequate response and repeat positive anti-IFX Ab measurements. Anti-IFX Ab can persist for years after discontinuation, which could impact efficacy and safety at retreatment. Continued IFX treatment may, however, be considered in patients with clinical response and a single positive anti-IFX Ab measurement, as anti-IFX Ab disappears in two-thirds of these during continued treatment.

Pathogenic Natural Antibodies Propagate Cerebral Injury Following Ischemic Stroke in Mice

Self-reactive natural Abs initiate injury following ischemia and reperfusion of certain tissues, but their role in ischemic stroke is unknown. We investigated neoepitope expression in the postischemic brain and the role of natural Abs in recognizing these epitopes and mediating complement-dependent injury. A novel IgM mAb recognizing a subset of phospholipids (C2) and a previously characterized anti-annexin IV mAb (B4) were used to reconstitute and characterize injury in Ab-deficient Rag1(-/-) mice after 60 min of middle cerebral artery occlusion and reperfusion. Reconstitution with C2 or B4 mAb in otherwise protected Rag1(-/-) mice restored injury to that seen in wild-type (wt) mice, as demonstrated by infarct volume, demyelination, and neurologic scoring. IgM deposition was demonstrated in both wt mice and reconstituted Rag1(-/-) mice, and IgM colocalized with the complement activation fragment C3d following B4 mAb reconstitution. Further, recombinant annexin IV significantly reduced infarct volumes in wt mice and in Rag1(-/-) mice administered normal mouse serum, demonstrating that a single Ab reactivity is sufficient to develop cerebral ischemia reperfusion injury in the context of an entire natural Ab repertoire. Finally, C2 and B4 mAbs bound to hypoxic, but not normoxic, human endothelial cells in vitro. Thus, the binding of pathogenic natural IgM to postischemic neoepitopes initiates complement-dependent injury following murine cerebral ischemia and reperfusion, and, based also on previous data investigating IgM reactivity in human serum, there appears to be a similar recognition system in both mouse and man.

Automated Parametrization of AMBER Force Field Terms from Vibrational Analysis with a Focus on Functionalizing Dinuclear Zinc(II) Scaffolds.

A procedure for determining force constants that is independent of the internal redundant coordinate choice is presented. The procedure is based on solving each bond and angle term separately, using the Wilson B matrix. The method only requires a single ab initio frequency calculation at the minimum energy structure and is made available in the software "parafreq". The methodology is validated with a set of small molecules, by showing it can reproduce ab initio frequencies better than other methods such as taking the diagonal terms of the Hessian in internal coordinates or by using standard AMBER force fields. Finally, the utility of the method is demonstrated by parametrizing the dizinc scaffold of bis-dipicolylamine (BDPA) bound to phosphotyrosine, which is then functionalized into promising antitumor drug proteomimetics.

The unexpected but predictable tetrazole packing in flexible 1-benzyl-1H-tetrazole

The crystal structure of 1-benzyl-1H-tetrazole, C8H8N4, was undertaken to study the geometry and intermolecular interactions of the (1-substituted) 1H-tetrazole moiety. It crystallizes in the monoclinic space group P21 with unit cell dimensions a = 7.6843(5), b = 5.5794(4), c = 9.4459(7) A, β = 100.949(4)°, V = 397.61(5) A3, Z = 2, density (calculated) = 1.338 gcm−3. The packing of the molecules in the crystal structure is dominated by a number of weak intermolecular hydrogen bonds of the type CH⋯N and CH⋯C. This results in segregated infinite S-shaped layers of phenyl and tetrazole rings where each tetrazole ring is coordinated by six others. There are no π⋯π interactions. A group developing crystal structure prediction methods for highly flexible molecules was challenged to predict this Z′ = 1 crystal structure from the chemical diagram. The experimental structure was found, having essentially the same lattice energy (ΔElatt ∼0.1 kJmol−1) as the most stable computationally generated structure, which had the expected π⋯π interaction and no segregation of tetrazole rings. The successful crystal structure prediction confirms that the intra and intermolecular interactions of the tetrazole group can be adequately represented by single molecule ab initio-based methods, which represent the electrostatic effects of the lone pairs and π electron density. The predicted structure provided a starting model, which was easily refined in SHELXL-97, providing indisputable proof that it is an accurate reproduction of the crystal structure.

Increased expression of microRNA miR‐326 in type 1 diabetic patients with ongoing islet autoimmunity

The current paradigm that microRNAs represent a new layer of gene regulation has generated much interest in this field. MicroRNAs have emerged as important regulatory factors involved in the developmental processes and in the regulation of insulin secretion and signalling. Furthermore, recent studies revealed an altered microRNA profiling in lymphocytes of patients with autoimmune diseases like multiple sclerosis, in which a hyperexpression of miR-326 was reported. Here, we analysed the expression levels of miR-326 in peripheral blood lymphocytes from type 1 diabetic (T1D) patients in relationship with ongoing islet autoimmunity. Peripheral blood lymphocytes were obtained from 19 T1D patients; 4/19 patients were positive for both glutamic acid decarboxylase (GAD) and islet cell antigen 512 autoantibodies; 10/19 were single GAD or IA-2 Ab positive and 5/19 were GAD antibodies and IA-2 antibodies (IA-2A) negative. Quantitative analysis of miR-326 was performed using specific stem-loop primers followed by real-time polymerase chain reaction. All values were normalized to endogenous control U6. miR-326 resulted increased in Ab-positive versus Ab-negative T1D subjects. Its expression levels were 2.05±0.38-fold increased in peripheral blood lymphocytes from patients expressing both GADA and IA-2A and 2.93±0.46-fold increased in single Ab-positive versus Ab-negative individuals (p<0.05). In conclusion, we have shown that miR-326 is expressed at higher levels in T1D subjects with ongoing islet autoimmunity, similar to what has been observed in multiple sclerosis, in which levels of this microRNA were highly correlated with disease severity. Interestingly, an online search of miR-326 predicted targets revealed vitamin D receptor and Erythroblastosis virus E26 oncogene homologue 1, two molecules highly involved in immune regulation.

The coupling constant polarizability and hyperpolarizabilty of 1J(NH) in N-methylacetamide, and its application for the multipole spin-spin coupling constant polarizability/reaction field approach to solvation

We present a benchmark study of a combined multipole spin-spin coupling constant (SSCC) polarizability/reaction field (MJP/RF) approach to the calculation of both specific and bulk solvation effects on SSCCs of solvated molecules. The MJP/RF scheme is defined by an expansion of the SSCCs of the solvated molecule in terms of coupling constant dipole and quadrupole polarizabilities and hyperpolarizabilities derived from single molecule ab initio calculations. The solvent electric field and electric field gradient are calculated based on data derived from molecular dynamics (MD) simulations thereby accounting for solute-solvent dynamical effects. The MJP/RF method is benchmarked against polarizable QM/MM calculations for the one-bond N-H coupling constant in N-methylacetamide. The best agreement between the MJP/RF and QM/MM approaches is found by truncating the electric field expansion in the MJP/RF approach at the linear electric field level. In addition, we investigate the sensitivity of the results due to the choice of one-electron basis set in the ab initio calculations of the coupling constant (hyper-)polarizabilities and find that they are affected by the basis set in a way similar to the coupling constants themselves.

Floor Time Play with a Child with Autism: A Single-Subject Study

Children with autism exhibit difficulties with social interaction and communication skills, and they present with restricted interests and stereotyped patterns of behaviour that affect their daily lives. Floor time play (FTP) is an intervention approach that addresses these issues; however, there are few published studies on its effectiveness. This study determines the effectiveness of FTP intervention with a child diagnosed with autism. A single subject AB design was used with circles of communication as the behaviour indicator for improvement. Visual and statistical analyses were completed. The child's mother kept a daily journal describing FTP intervention sessions at home. Despite variability in the data, statistical analyses indicate a significant difference between the numbers of circles of communication during the intervention phase as compared with the observation phase. Implications. This study provides preliminary evidence for the use of the FTP approach with a child with autism.

Identification of Key Amino Acid Residues That Determine the Ability of High Risk HPV16-E7 to Dysregulate Major Histocompatibility Complex Class I Expression

High risk human Papillomavirus (HPV) types are the major causative agents of cervical cancer. Reduced expression of major histocompatibility complex class I (MHC I) on HPV-infected cells might be responsible for insufficient T cell response and contribute to HPV-associated malignancy. The viral gene product required for subversion of MHC I synthesis is the E7 oncoprotein. Although it has been suggested that high and low risk HPVs diverge in their ability to dysregulate MHC I expression, it is not known what sequence determinants of HPV-E7 are responsible for this important functional difference. To investigate this, we analyzed the capability to affect MHC I of a set of chimeric E7 variants containing sequence elements from either high risk HPV16 or low risk HPV11. HPV16-E7, but not HPV11-E7, causes significant diminution of mRNA synthesis and surface presentation of MHC I, which depend on histone deacetylase activity. Our experiments demonstrate that the C-terminal region within the zinc finger domain of HPV-E7 is responsible for the contrasting effects of HPV11- and HPV16-E7 on MHC I. By using different loss- and gain-of-function mutants of HPV11- and HPV16-E7, we identify for the first time a residue variation at position 88 that is highly critical for HPV16-E7-mediated suppression of MHC I. Furthermore, our studies suggest that residues at position 78, 80, and 88 build a minimal functional unit within HPV16-E7 required for binding and histone deacetylase recruitment to the MHC I promoter. Taken together, our data provide new insights into how high risk HPV16-E7 dysregulates MHC I for immune evasion.

GaN HEMT Based High Power and High Efficiency Doherty Amplifiers with Digital Pre-Distortion Correction for WiBro Applications

This paper presents high power and high efficiency Doherty amplifiers for 2.345 GHz wireless broadband (WiBro) applications that use a Nitronex 125-W (<TEX>$P_{3dB}$</TEX>) GaN high electron mobility transistor (HEMT). Two- and three-way Doherty amplifiers and a saturated Doherty amplifier using Class-F circuitry are implemented. The measured result for a center frequency of 2.345 GHz shows that the two-way Doherty amplifier attains a high <TEX>$P_{3dB}$</TEX> of 51.5 dBm, a gain of 12.5 dB, and a power-added efficiency (PAE) improvement of about 16 % compared to a single class AB amplifier at 6-dB back-off power region from <TEX>$P_{3dB}$</TEX>. For a WiBro OFDMA signal, the Doherty amplifier provides an adjacent channel leakage ratio (ACLR) at 4.77 MHz offset that is -33 dBc at an output power of 42 dBm, which is a 9.5 dB back-off power region from <TEX>$P_{3dB}$</TEX>. By employing a digital pre-distortion (DPD) technique, the ACLR of the Doherty amplifier is improved from -33 dBc to -48 dBc. The measured result for the same frequency shows that the three-way Doherty amplifier, which has a <TEX>$P_{3dB}$</TEX> of 53.16 dBm and a gain of 10.3 dB, and the saturated Doherty amplifier, which has a <TEX>$P_{3dB}$</TEX> of 51.1 dBm and a gain of 10.3 dB, provide a PAE improvement of 11 % at the 9-dB back-off power region and 7.5 % at the 6-dB back-off region, respectively, compared to the two-way Doherty amplifier.

Benchmarking the multipole shielding polarizability/reaction field approach to solvation against QM/MM: Applications to the shielding constants of N-methylacetamide

We present a benchmark study of a combined multipole shielding polarizability/reaction field (MSP/RF) approach to the calculation of both specific and bulk solvation effects on nuclear magnetic shielding constants of solvated molecules. The MSP/RF scheme is defined by an expansion of the shielding constants of the solvated molecule in terms of electric field and field gradient property derivatives derived from single molecule ab initio calculations. The solvent electric field and electric field gradient are calculated based on data derived from molecular dynamics simulations, thereby accounting for solute-solvent dynamical effects. The MSP/RF method is benchmarked against polarizable quantum mechanics/molecular mechanics (QM/MM) calculations. The best agreement between the MSP/RF and QM/MM approaches is found by truncating the electric field expansion in the MSP/RF approach at the linear electric field level which is due to the cancelation of errors. In addition, we investigate the sensitivity of the results due to the choice of one-electron basis set in the ab initio calculations of the property derivatives and find that these derivatives are affected by the basis set in a way similar to the shielding constants themselves.

PKa prediction from an ab initio bond length: Part 3—benzoic acids and anilines

The prediction of pK(a) from a single ab initio bond length has been extended to provide equations for benzoic acids and anilines. The HF/6-31G(d) level of theory is used for all geometry optimisations. Similarly to phenols (Part 2 of this series of publications), the meta-/para-substituted benzoic acids can be predicted from a single model constructed from one bond length. This model had an impressive RMSEP of 0.13 pK(a) units. The prediction of ortho-substituted benzoic acids required the identification of high-correlation subsets, where the compounds in the same subset have at least one of the same (e.g. halogens, hydroxy) ortho substituent. Two pK(a) equations are provided for o-halogen benzoic acids and o-hydroxybenzoic acids, where the RMSEP values are 0.19 and 0.15 pK(a) units, respectively. Interestingly, the bond length that provided the best model differed between these two high-correlation subsets. This demonstrates the importance of investigating the most predictive bond length, which is not necessarily the bond involving the acid hydrogen. Three high-correlation subsets were identified for the ortho-substituted anilines. These were o-halogen, o-nitro and o-alkyl-substituted aniline high-correlation subsets, where the RMSEP ranged from 0.23 to 0.44 pK(a) units. The RMSEP for the meta-/para-substituted aniline model was 0.54 pK(a) units. This value exceeded our threshold of 0.50 pK(a) units and was higher than both the m-/p-benzoic acids in this work and the m-/p-phenols (RMSEP = 0.43) of Part 2. Constructing two separate models for the meta- and para- substituted anilines, where RMSEP values of 0.63 and 0.33 pK(a) units were obtained respectively, revealed it was the meta-substituted anilines that caused the large RMSEP value. For unknown reasons the RMSEP value increased with the addition of a further twenty meta-substituted anilines to this model. The C-N bond always produced the best correlations with pK(a) for all the high-correlation subsets. A higher level of theory and an ammonia probe improved the statistics only marginally for the hydroxybenzoic acid high-correlation subsets.

Cognitive Behaviour Therapy for Withdrawal from Antidepressant Medication: A Single Case Series

Research has clearly established the efficacy of pharmacotherapy and cognitive behaviour therapy (CBT) for depression. There is less literature addressing cessation of treatment, such as relapse during withdrawal from antidepressant medication. The current study examines the role of psychological constructs that may influence relapse or fear of relapse and lead to resumption of medication. This hypothesizes that during withdrawal individuals may misinterpret normal variations in mood and dysphoric or other symptoms as reduced levels of medication in their bodies in keeping with a simplistic rationale for antidepressants. The study uses an intensive single case AB style design in three cases during the withdrawal process. All participants had been treated with CBT plus antidepressants and had previously attempted to withdraw from antidepressants. The first part of the study naturalistically tracks belief changes as medication decreases; the second examines changes in these if/when a CBT intervention is introduced due to relapse or potential near-relapse. Daily self-monitoring diaries were used to measure target variables, together with standardized questionnaires up to 6 months follow-up. Changes in symptoms, appraisal of symptoms, and beliefs about medication changed throughout the study. All participants remained medication free at 6 months follow-up. Two cases received CBT intervention due to possible relapse; the third underwent an unproblematic withdrawal. Patterns of change are discussed in terms of current approaches to medication cessation and the role of CBT during withdrawal.

AB-Block Copolymer with Moving B Blocks as a Model for Interpolymer Complexes

The conformational behavior of a single AB block copolymer is studied by Monte Carlo simulation. The A-A and A-B interactions have the character of excluded volume interactions while the B units attract each other; the attractive B blocks can move along the chain. The collapse transition of the chain with increasing attraction between the B units is analyzed. Intrachain separation of the A and B units takes place in the course of the chain collapse with the formation of “globule with a tail” conformations. The globule is formed by the attractive moving B blocks while the tail consists of the swollen A segments. The model of AB block copolymer with moving B blocks can describe the behavior of interpolymer complexes between a long macromolecule and shorter polymer chains.

Amyloid Beta Oligomer Studied by Newly Developed Single Molecule Analysis Method

Amyloid beta (Ab) is 4 kDa peptide which forms aggregates such as oligomers and fibrils. They have been considered to cause Alzheimer's diseases (AD). Recent results have suggested that soluble Ab oligomers are the causative agent of AD since such oligomers are more cytotoxic than fibrils. It was also suggested that Ab oligomers affect not only cell death but also early stage of cell dysfunction and cause memory loss.However, the formation mechanism of these soluble oligomers is still unknown. In this study, we developed new single molecule analysis method that can analyze Ab oligomer distribution. For this purpose, we combined total internal reflection fluorescence microscopy (TIRFM) with photon counting histogram (PCH) (Terada, N. et al. (2007) Biophys. J. 92, 2162). Using TIRFM, fluorescent intensity of monomer is obtained from discrete photobleaching. Using PCH method, the number of protomers in oligomers and concentrations are obtained from histograms of photons from fluorescent molecules diffusing through the confocal volume.A model Ab oligomer was prepared by sonication treatment of Ab fibrils made from FITC labeled Ab monomer. The number of Ab monomer in a single Ab oligomer was estimated by TIRFM, which agrees well with the results of PCH analysis. Thus we concluded that PCH can be applied to analyze Ab oligomer formation. Next, Ab oligomers were formed at physiological Ab concentration (LeVineIII, H. (2004) Anal. Biochem. 335, 81). Oligomer formation was observed with TIRFM analysis. PCH analysis is now in pregress.

Intracellular Expression of a Single Domain Antibody Reduces Cytotoxicity of 15-Acetyldeoxynivalenol in Yeast

15-Acetyldeoxynivalenol (15-AcDON) is a low molecular weight sesquiterpenoid trichothecene mycotoxin associated with Fusarium ear rot of maize and Fusarium head blight of small grain cereals. The accumulation of mycotoxins such as deoxynivalenol (DON) and 15-AcDON within harvested grain is subject to stringent regulation as both toxins pose dietary health risks to humans and animals. These toxins inhibit peptidyltransferase activity, which in turn limits eukaryotic protein synthesis. To assess the ability of intracellular antibodies (intrabodies) to modulate mycotoxin-specific cytotoxocity, a gene encoding a camelid single domain antibody fragment (V(H)H) with specificity and affinity for 15-AcDON was expressed in the methylotropic yeast Pichia pastoris. Cytotoxicity and V(H)H immunomodulation were assessed by continuous measurement of cellular growth. At equivalent doses, 15-AcDON was significantly more toxic to wild-type P. pastoris than was DON. In turn, DON was orders of magnitude more toxic than 3-acetyldeoxynivalenol. Intracellular expression of a mycotoxin-specific V(H)H within P. pastoris conveyed significant (p = 0.01) resistance to 15-AcDON cytotoxicity at doses ranging from 20 to 100 mug.ml(-1). We also documented a biochemical transformation of DON to 15-AcDON to account for the attenuation of DON cytotoxicity at 100 and 200 mug.ml(-1). The proof of concept established within this eukaryotic system suggests that in planta V(H)H expression may lead to enhanced tolerance to mycotoxins and thereby limit Fusarium infection of commercial agricultural crops.

High Accuracy ab Initio Calculations on Reactions of OH with 1-Alkenes. The Case of Propene.

The energetics of terminal, central OH-additions as well as allylic H-abstractions by OH in its reaction with propene was studied as proxies for the 1-alkenes + OH reactions using several single and multireference ab initio techniques with basis set extrapolation where possible. Selection of the localized occupied orbitals forming the active space for multireference methods is discussed. Initial geometries of the reactants, prereaction complex (π-complex), and transition states were determined at the [5,5]-CASPT2/cc-pVTZ level of theory. Frequency analysis was also carried out at this level with the introduction of a scale factor. Analyzing the results, it will be concluded that multireference effects are negligible, and from the various single reference models we will opt for UCCSD(T)/cc-pVTZ for final geometry optimizations and vibrational frequency analysis. These results will be compared with those from approximate models yielding information on the reliability of the latter. Triples contributions are found to be very important, except for the π-complex, which has a UCCSD(T)/CBS relative enthalpy of -10.56 kJ/mol compared to infinitely separated propene + OH. The addition transition states are found to have relative enthalpies of -9.93 kJ/mol for the central and -9.84 kJ/mol for the terminal case. Allylic abstraction mechanisms, although lying significantly higher, still have only slightly positive barriers - a value of 3.21 kJ/mol for the direct and 1.67 kJ/mol for the consecutive case. Conventional transition state theory was used as a rough estimation for determining rate constants and turned out to agree well with experimental data.

Structure and crystal chemistry of fluorite-related Bi 38Mo 7O 78 from single crystal X-ray diffraction and ab initio calculations

The floating-zone furnace method was used to synthesize single crystals of the fluorite-related δ-Bi 2O 3-type phase Bi 38Mo 7O 78 for the first time. Single crystal synchrotron X-ray diffraction data, in conjunction with ab initio (density functional theory) calculations, were used to solve, optimize, and refine the 5×3×3 commensurate superstructure of fluorite-type δ-Bi 2O 3 in Pbcn ( a=28.7058(11) Å, b=16.8493(7) Å and c=16.9376(6) Å, Z=4, R F =11.26%, w R I =21.67%). The structure contains stepped channels of Mo 6+ in tetrahedral environments along the b axis and chains of Mo 6+ in octahedral environments along the ac plane. The role of the stepped channels in oxide ion conduction is discussed. The simultaneous presence of both tetrahedral and octahedral coordination environments for Mo 6+, something not previously observed in Mo 6+-doped δ-Bi 2O 3-type phases, is supported by charge balance considerations in addition to the results of crystallographic and ab initio analysis.

Outflow Facility in Isolated Porcine Eyes after Creation of an Intrascleral Canal by Injection of Stabilized Hyaluronic Acid

To investigate outflow facility in isolated porcine eyes after creation of an intrascleral canal by injection of stabilized, nonanimal, hyaluronic acid gel (NASHA; Q-Med AB, Uppsala, Sweden). Outflow facility of 60 porcine eyes was measured after creation of an intrascleral canal into the anterior chamber by injection of NASHA gel using six different combinations of needle size (21, 23, and 27 gauge) and canal length (4.6 mm). Ten eyes were tested in each of the six subgroups and an additional 10 were control eyes. After cannulation of the anterior chamber and adjustment of the inflow rate to achieve a stable pressure of 10 mm Hg, an intrascleral channel was created by injection of NASHA gel. The inflow rate was then increased to achieve a stable pressure of 20 mm Hg and then again adjusted to maintain a stable pressure of 30 mm Hg. A significant increase in outflow facility was found between the control group and the NASHA gel-injected group (60 eyes) for both the 10- to 20-mm Hg and the 20- to 30-mm Hg pressure change (P < 0.001). Increase in outflow facility was independent of the canal lengths and the needle sizes used for both the 10- to 20-mm Hg (P = 0.82) and 20- to 30-mm Hg (P = 0.99) pressure change. A single ab externo intrascleral canal created by injection of NASHA gel increases the outflow facility in isolated porcine eyes. This is a potentially promising new technique for lowering intraocular pressure. It remains to be seen whether these positive results can be reproduced for significant periods in humans.

Crystal Structure and Conformational Analysis of 4-[(p-N,N-Dimethylamino) benzylidene]-2-(3,5-dinitrophenyl)oxazole-5-one

ABSTRACT An azlactone derivative, 4-[(p-N,N-dimethylamino)benzylidene]-2-(3,5-dinitrophenyl)oxazol-5-one (DNPO), C18H14N4O6, has been synthesized, and its crystal structure has been investigated by single crystal X-ray analysis and ab initio method. DNPO is monoclinic, with a = 9.3628(4) Å, b = 13.5148(9) Å, c = 13.7701(6) Å, β = 92.921(4)°, Z = 4, Dx = 1.46 g/cm3, μ(MoKα) = 0.112 mm−1, and space group P 121/c1. The whole molecule is almost planar. The crystal structure is stabilized by C–H · · · N type intramolecular, C–H · · · O type intermolecular interactions. To determine the flexibility of DNPO, the selected torsion angle is varied from − 180° to 180° in steps of 10°, and the molecular energy profile is calculated and analyzed.

Conformal behavior of a single chain AB block copolymer with mobile B-blocks

Monte-Carlo computer modeling was used to investigate the conformal behavior of a single chain AB block copolymer with mobile hydrophobic B-blocks and hydrophilic A-links. The formation of a “tailed globule” was observed with an increase of the energy of attraction between hydrophobic links. A comparison between the collapsing of a chain with mobile blocks and the behavior of regular and random block copolymers of the same structure was conducted.