Оцінка впливу замісної гормоно-терапії гіпотиреозу на стан вагітності та виношування плоду

Гіпотиреоз – захворювання щитовидної залози, при якому знижується її продуктивність, тиреоїдних гормонів виробляється менше чим необхідно організму для нормальної життєдіяльності. За результатами популяційних досліджень, поширеність гіпотиреозу серед вагітних становить 2-3 %. Серед них близько двох третин мають субклінічний та 0,5 % − маніфестний гіпотиреоз. За даними багатьох дослідників, тільки 20-30% жінок з гіпотиреозом мають клінічні прояви гіпотиреозу, у інших, як правило, захворювання протікає без симптомів. Патологія ЩЗ негативно впливає на перебіг вагітності, розвиток плода й адаптацію новонародженого. Тиреоїдна дисфункція загрожує викиднями, передчасними пологами, відшаруванням плаценти, прееклампсією, післяпологовим тиреоїдитом у матері, а також зниженням інтелектуального потенціалу народжених дітей

Conducting Probe Atomic Force Microscopy Investigation of Anisotropic Charge Transport in Solution Cast PBD Single Crystals Induced by an External Field

2-(4-Biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxdiazole (PBD) is a good electron-transporting material and can form single crystals from solution. In this work, solution cast PBD single crystals with different crystallographic axes (b, c) perpendicular to the Au/S substrates in large area are achieved by controlling the rate of solvent evaporation in the presence and absence of external electrostatic field, respectively. The orientation of these single crystals on Au/S substrate was characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Conducting probe atomic force microscopy (CP-AFM) was used to measure the charge transport characteristics of PBD single crystals grown on Au/S substrates. Transport was measured perpendicular to the substrate between the CP-AFM tip and the Au/S substrate. The electron mobility of 3 × 10-3 cm2/(V s) for PBD single crystal along crystallographic b-axis is determined. And the electron mobility of PBD single crystal along the c-axis is about 2 orders of magnitude higher than that along the b-axis due to the anisotropic charge transport at the low voltage region. We demonstrate that CP-AFM may be applied successfully to measuring the anisotropic charge transport of single crystals over nanoscopic length scales

Rayleigh Instability Induced Cylinder-to-Sphere Transition in Block Copolymer Micelles: Direct Visualization of the Kinetic Pathway

Direct visualization of morphological evolution remains extremely challenging despite its critical importance to understand the basic fundamentals behind the transition. Here we report on the detailed observation of a spontaneous cylinder-to-sphere morphological transformation of amphiphilic poly­(2-vinylpyridine)-<i>b</i>-poly­(ethylene oxide) (P2VP-<i>b</i>-PEO) diblock copolymer micelles in aqueous solution, which first provides experimental evidence that the fragmentation pathway is driven by Rayleigh instability showing the distinctive signatures during the transition. Owing to the instability of cylindrical micelles and the fluidity of micellar cores, our results show that the cylindrical micelles spontaneously undulate and transform into spherical micelles through distinct intermediate states, including undulated cylinders and pearl-necklace-like micelles with a perfect sinusoidal wave throughout the length. Moreover, the present system with transitional morphology is proved to be able to act as a model to encapsulate hydrophobic guests in the micellar cores, which displays a relatively sustained release behavior. The specific kinetic pathway provides new insight into the mechanism of block copolymer micellar morphological transition; meanwhile, the dynamic system might serve as a promising candidate for unique nanostructure design as well as contribute to the transition-coupled guest delivery and controlled release

Single Crystals of Polythiophene with Different Molecular Conformations Obtained by Tetrahydrofuran Vapor Annealing and Controlling Solvent Evaporation

Single crystals of poly(3-hexylthiophene) (P3HT) and poly(3-octylthiophene) (P3OT) have been prepared by tetrahydrofuran vapor annealing and controlling solvent evaporation, respectively. The morphology and structure of the single crystals are characterized using optical microscopy, scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and wide-angle X-ray diffraction. It is observed that in P3HT single crystals, the molecules are packed with π−π stacking direction perpendicular to the length axis of the crystals and main chains parallel to the substrate, whereas in P3OT single crystals, the molecules are packed with π−π stacking direction parallel to the length axis of the crystal and main chains parallel to the substrate. In the field effect transistors, the current flow is parallel to the length axis of the single crystals, and the mobility is 1.57 × 10−3 cm2/Vs for a P3HT single crystal and 0.62 cm2/Vs for a P3OT single crystal. The single crystals of P3HT and P3OT showed high anisotropic electrical properties. The influences of molecular conformation and alkyl chain length on the electrical properties of P3ATs are discussed

Coupling of Microphase Separation and Dewetting in Weakly Segregated Diblock Co-polymer Ultrathin Films

We have studied the coupling behavior of microphase separation and autophobic dewetting in weakly segregated poly(ε-caprolactone)-block-poly(l-lactide) (PCL-b-PLLA) diblock co-polymer ultrathin films on carbon-coated mica substrates. At temperatures higher than the melting point of the PLLA block, the co-polymer forms a lamellar structure in bulk with a long period of L ∼ 20 nm, as determined using small-angle X-ray scattering. The relaxation procedure of ultrathin films with an initial film thickness of h = 10 nm during annealing has been followed by atomic force microscopy (AFM). In the experimental temperature range (100–140 °C), the co-polymer dewets to an ultrathin film of itself at about 5 nm because of the strong attraction of both blocks with the substrate. Moreover, the dewetting velocity increases with decreasing annealing temperatures. This novel dewetting kinetics can be explained by a competition effect of the composition fluctuation driven by the microphase separation with the dominated dewetting process during the early stage of the annealing process. While dewetting dominates the relaxation procedure and leads to the rupture of the ultrathin films, the composition fluctuation induced by the microphase separation attempts to stabilize them because of the matching of h to the long period (h ∼ 1/2L). The temperature dependence of these two processes leads to this novel relaxation kinetics of co-polymer thin films

Tuning Radial Lamellar Packing and Orientation into Diverse Ring-Banded Spherulites: Effects of Structural Feature and Crystallization Condition

Spherulite morphologies of a highly asymmetrical double crystallizable poly­(ε-caprolactone-<i>b</i>-ethylene oxide) diblock copolymer in solution-cast films were explored from a unified standpoint of tuning radial lamellar organization via controlled evaporation. Besides Maltese cross spherulites, three kinds of ring-banded spherulites that display non- and half-birefringent concentric ringed features as well as extinction banding were first encountered in the same polymer. Structural analyses based on atomic force microscopy, transmission electron microscopy, and grazing incidence X-ray technique revealed that concentric ringed spherulites possess the nature of a rhythmic variation of the radial lamellar packing and extinction banded spherulites have the origin of a periodic change of the radial lamellar orientation. Morphological transitions among different kinds of spherulites were achieved by altering the drying condition. PEO segment crystallized at low temperatures even if it is being confined by PCL lamellae. Combined with poly­(ε-caprolactone) and poly­(ethylene adipate), the influences of structural feature and crystallization condition on radial lamellar organization of polymer spherulites were discussed. These present findings are encouraged to enhance our understanding and then governing generation of expected polymer crystal morphology for special material performance

Interplay between Stereocomplexation and Microphase Separation in PS‑<i>b</i>‑PLLA‑<i>b</i>‑PDLA Triblock Copolymers

Polymers with different tacticities or chiralities can self-assemble into stereocomplex structure (sc-structure) which may further self-assemble into sc-crystals. This stereocomplexation behavior has a great potential in enhancing the crystallization and mechanical properties of polymers. However, less is known about its interplay with microphase separation (MS) in controlling the microscopic structures of block copolymers. In this work, we have designed and synthesized two series of PS-b-PDLA-b-PLLA (PS-b-PLLA-b-PDLA) triblock copolymers. By introducing a PDLA block into a strong segregation PS-b-PLLA system, we were able to explore the interplay between stereocomplexation, crystallization, and MS. The first series of triblock polymers have a fixed total molecular weight and a PLA weight fraction about 0.3, corresponding to a cylinder MS structure. By increasing the relative PDLA:PLLA composition approaching to unity within the PLA block, we found that the long period, L0, of the MS structure decreases due to the formation of sc-structure. However, crystallization was completely suppressed under the strong confinement as no characteristics of sc-crystal could be detected by DSC and WAXS. In the second series, triblock copolymers with the same PS-b-PLLA block but a varying PDLA block were synthesized. With increasing the PDLA length, the MS structure undergoes a transition from cylinder to lamellae. Interestingly, because of the sc-structure formation, the long period of the lamellar phase only increases slightly with increasing PDLA length. Despite the confinement of MS, exclusive sc-crystals could be formed within the lamellae. Our results demonstrate that the confinement of MS structure has a strong impact on sc-crystallization and sterocomplexation within the PLA domains, which provide a new strategy for further adjusting the microstructure as well as various properties of PLA-based materials

Engineering Hybrid Metallic Nanostructures Using a Single Domain of Block Copolymer Templates

Building complex nanostructures using a simple patterned template is challenging in material science and nanotechnology. In the present work, three different strategies have been exploited for the successful fabrication of hybrid dots-on-wire metallic nanostructures through combining an in-situ method with an ex-situ method. Basically, plasma etching was applied to generate a metallic wire-like nanostructure, and preformed nanoparticles could be placed through multiple means before or after the formation of the wire-like nanostructure. Various monometallic and bimetallic nanostructures have been obtained by utilizing only one functional domain of block copolymer templates. In these cases, full utilization of the functional domain or introduction of the molecular linker is critical to engineering hybrid metallic nanostructures. Other complex and multifunctional hybrid nanostructures can be developed via these strategies similarly, and these nanostructures are promising for useful applications such as optics and surface-enhanced Raman spectroscopy (SERS)

Solvent-Induced Morphology of the Binary Mixture of Diblock Copolymer in Thin Film: The Block Length and Composition Dependence of Morphology

A series of binary SB blend samples with various overall volume fraction of PS (ΦPS) and different discrete distribution of the block length (denoted as dPS or dPB) were prepared by mixing various asymmetric poly(styrene)-block-poly(butadiene) (SB) block copolymers with a symmetric SB block copolymer. The influences of the external solvent field, composition, and the block length distribution on the morphologies of the blends in the thin films were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The experimental results revealed that after solvent annealing, the interface of the blend thin films depended mainly on the cooperative effects of the annealing solvent and the inherently interfacial curvature of the blends. Upon exposure to the saturated vapor of cyclohexane, which has preferential affinity for the PB block, a “threshold” of ΦPS (approximate 0.635∼0.707) was found. Below such threshold, the influence of the annealing solvent played an important role on the interfacial curvature of the blend thin film. The morphologies of the thin films and the long-range order of the structures were related to the value of dPS, regardless of the change of dPB

<i>In Situ</i> Study of the Breakout Crystallization in the Poly(butadiene)-<i>block</i>-Poly(ε-caprolactone) Thin Film

Despite its wide occurrence in soft confined block co-polymers, breakout crystallization remains poorly understood and is difficult to control. In this work, thin films of cylinder-forming poly­(butadiene)-<i>block</i>-poly­(ε-caprolactone) (PB-<i>b</i>-PCL) diblock co-polymers, with PCL being the minority block, have been chosen as the study subject. We demonstrate a new route to study the breakout crystallization by obtaining the microphase separation structure within terraced lamellae first and then <i>in situ</i> tracking down the lamellar coalescence, resulting from the development of the crystal growth front. We find that the crystal growth front has sucked materials from the surrounding amorphous lamellae, which lead to the decrease of the lamellar zones and coalescence of the microphase separation structure. Dividing the breakout crystallization into parallel breakout and vertical breakout, we illustrate that it is the crystallization-driven molecular diffusion that make the molecules overcome the topography constraint and grow into large-scale spherulite. Moreover, the results show that the polymer microphase separation structure has a significant influence on the crystal nucleation and greatly retarded the crystal growth rate. With a well-designed microphase separation structure within terraces and an easily tunable atomic force microscopy <i>in situ</i> imaging technique, an intensive study of the breakout crystallization and concomitant microdomain coalescence has been offered