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1.
Phys Chem Chem Phys ; 26(13): 10144-10155, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38488033

RESUMO

Chiral liquid crystalline compounds belonging to the homologous series of (S)-4'-(1-methylheptyloxycarbonyl)biphenyl-4-yl 4-[m-(2,2,3,3,4,4,4-heptafluorobutoxy)alk-1-oxy]-2-fluorobenzoates show various behaviors on cooling depending on the length of the CmH2m chain. The homologue with m = 2 crystallizes, while for m = 5, 6, 7, and presumably also for m = 3, the glass of the anticlinic smectic CA* phase is formed. The previous results for m = 4 suggest that this homologue may also be a glassformer. This paper presents the study of the crystallization kinetics for the compound with m = 4 in isothermal conditions (by polarizing optical microscopy) and for the 5-40 K min-1 cooling rates (by differential scanning calorimetry). Microscopic observations enable estimation of the energy barrier for nucleation, which equals 409 kJ mol-1. The threshold cooling rate necessary for complete vitrification of the smectic CA* phase, obtained by extrapolating the enthalpy change during crystallization to zero, is equal to 81 K min-1 or 64 K min-1 for the linear and parabolic fits, respectively. The structural studies by X-ray diffraction show that crystal phases have lamellar structures both in the pristine sample and after crystallization from the melt but with different layer spacing. A weak relaxation process is detected in the sample after melt crystallization, revealing the presence of the conformational disorder. The dynamic glass transition temperature of the SmCA* phase, estimated from the relaxation time of the PH process (as the α-relaxation time could not be registered in a wide enough temperature range), is 244 K.

2.
J Clin Ultrasound ; 50(9): 1279-1285, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36129368

RESUMO

PURPOSE: This article aimed to present the factors determining survival and prognosis in fetuses and newborns with critical prenatal aortic stenosis (AS) and to present 26 years of tertiary center experience. METHODS: Study included 87 fetuses with critical AS requiring surgical intervention during neonatal period. All results were expressed as means ± SD, in numbers and percentages. The statistically significant results were those with p < 0.05. RESULTS: An increase in the number of cases of AS was observed in our center along with a decrease in gestational age of our patients during the first echocardiographic exam. The survival rate of newborns was considerably higher when born in due time (p < 0.05) with body weight > 2500 g (p < 0.05). Balloon valvuloplasty performed in the first days after birth occurred to be an optimal solution in these cases. CONCLUSIONS: Fetal echocardiography and special perinatal care with transplacental maternal pharmacotherapy in selected cases and an early neonatal aortic balloon valvuloplasty have shown improvement in survival rate. The most dangerous for the newborn with AS was the first week of postnatal life. It is vital to refer the fetuses with AS to the reference centers which offer the possibility of invasive cardiac intervention on the first day after birth, and it might be an optimal solution.


Assuntos
Estenose da Valva Aórtica , Valvuloplastia com Balão , Gravidez , Feminino , Recém-Nascido , Humanos , Valvuloplastia com Balão/métodos , Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/cirurgia , Ecocardiografia , Idade Gestacional , Estudos Retrospectivos , Resultado do Tratamento
3.
Molecules ; 27(12)2022 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-35744787

RESUMO

Modification of the physical properties of the (S)-MHPOBC antiferroelectric liquid crystal (AFLC) by doping with low concentrations of gold nanoparticles is presented for the first time. We used several complementary experimental methods to determine the effect of Au nanoparticles on AFLC in the metal-organic composites. It was found that the dopant inhibits the matrix crystallization process and modifies the phase transitions temperatures and switching time, as well as increases the helical pitch and spontaneous polarization, while the tilt angle slightly changes. We also showed that both the LC matrix and Au nanoparticles show strong fluorescence in the green light range, and the contact angle depends on the temperature and dopant concentration.

4.
Int J Mol Sci ; 23(1)2021 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-35008471

RESUMO

The aim of our study was to analyze the influence of various concentrations of γ-Fe2O3 nanoparticles on the physical properties of the liquid crystalline ferroelectric SmC* phase, as well as to check the effect of introducing nanoparticles in the LC matrix on their properties in the prepared five nanocomposites. UV-vis spectroscopy showed that the admixture reduced the absorption of nanocomposites in the UV range, additional absorption bands appeared, and all nanocomposites were transparent in the range of 500-850 nm. The molecular dynamics in particular phases of the nanocomposites were investigated by the dielectric spectroscopy method, and it was found that nanoparticles caused a significant increase in the dielectric constant at low frequencies, a strong modification of the dielectric processes in the SmC* phase, and the emergence of new relaxation processes for the highest dopant concentrations. SQUID magnetometry allowed us to determine the magnetic nature of the nanoparticles used, and to show that the blocked state of nanoparticles was preserved in nanocomposites (hysteresis loops were also registered in the ferroelectric SmC* phase). The dependence of the coercive field on the admixture concentration and the widening of the hysteresis loop in nanocomposites in relation to pure nanoparticles were also found. In turn, the FT-MIR spectroscopy method was used to check the influence of the impurity concentration on the formation/disappearance or modification of the absorption bands, and the modification of both the FWHM and the maximum positions for the four selected vibrations in the MIR range, as well as the discontinuous behavior of these parameters at the phase transitions, were found.


Assuntos
Compostos Férricos/química , Nanopartículas/química , Magnetismo/métodos , Nanocompostos/química , Tamanho da Partícula , Transição de Fase
5.
BMC Pediatr ; 20(1): 370, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32758206

RESUMO

BACKGROUND: Atrial flutter (AFL) is a supraventricular tachyarrhythmia. In the ECG tracing, it is marked by a fast, irregular atrial activity of 280-500 beats per minute. AFL is known to be a rare and also life-threatening rhythm disorder both at the fetus and neonatal period. AFL may result in circulatory failure, and in a more severe form, it may lead to a non-immune fetal hydrops. However, with early prenatal diagnosis and proper treatment, the majority of AFL cases show a good prognosis. CASE PRESENTATION: We report a case of a neonate who was born at 34 weeks of gestational age by C-section because of risk for birth asphyxia, based on abnormal CTG tracing, which had no characteristic rhythms for fetal decelerations. A third day his heart rate was 220/bpm. ECG has shown supraventricular tachycardia with narrow QRS. The administration of adenosine resulted in the obvious appearance of "sawtooth wave" typical for AFL. Arrhythmia was resistant to the therapy of amiodaron. Then cardioversion was performed and the rhythm converted to normal. CONCLUSIONS: As neonatal AFL might be resistant to conventional pharmacotherapy, one needs to remember about the possibility of electrical cardioversion in the pediatric cardiology referral center. Moreover, CTG monitoring is of limited use because it does not record fetal heart rhythms > 200/min and echocardiography at the reference center is practically the only method to monitor the condition of the fetus with abnormal rapid heart rhythm.


Assuntos
Flutter Atrial , Cardioversão Elétrica , Antiarrítmicos/uso terapêutico , Arritmias Cardíacas , Flutter Atrial/diagnóstico , Flutter Atrial/tratamento farmacológico , Criança , Digoxina , Feminino , Humanos , Recém-Nascido , Gravidez
6.
Reumatologia ; 58(1): 4-8, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32322117

RESUMO

OBJECTIVES: Specific systemic autoimmune syndrome characterized by inflammatory myopathy, arthritis or arthralgias, interstitial lung disease (ILD), fever, Raynaud's phenomenon, and mechanic's hands is called antisynthetase syndrome (AS). The aim of this study was to assess the clinical spectrum associated with presence of aminoacyl-transfer RNA synthetase autoantibodies (ASA). MATERIAL AND METHODS: A total of 305 patients with presence of myositis-specific autoantibodies were identified in the database of immunological tests performed in the Clinical Immunology and Transplantology Unit, Medical University of Gdansk between January 2011 and March 2016. In 110 patients (36%) ASA were detected. The detailed analysis included 50 patients with ASA for whom full clinical data were available. RESULTS: The incidence of specific ASA in the analyzed group was: Jo-1 46% (23 patients), PL-12 32% (16 patients), PL-7 16% (8 patients), OJ 12% (6 patients), EJ 6% (3 patients). In 10% (5 patients) there was coexistence of at least one ASA, and in another 5 patients there was coexistence of ASA with other antibodies specific for myositis (MSA). In the analyzed group of patients 11 (22%) satisfied the Bohan and Peter criteria for dermatomyositis, 1 for polymyositis. In 5 patients (10%) based on clinical presentation and ASA presence the AS was recognized. Another 3 patients met the criteria of the overlap syndrome polymyositis respectively with systemic lupus, rheumatoid arthritis, and scleroderma. In 5 patients undifferentiated connective tissue disease was diagnosed, and 14 consecutive patients were diagnosed with other connective tissue diseases, while 12 patients did not receive a definitive diagnosis. CONCLUSIONS: The clinical presentation of patients with the presence of ASA is varied. Their presence indicates not only idiopathic inflammatory myopathies, but also non-specifically other disease entities. These patients require observation for the development of idiopathic inflammatory myopathy, and ILD.

7.
Materials (Basel) ; 17(14)2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-39063822

RESUMO

Currently, new functional materials are being created with a strong emphasis on their ecological aspect. Materials and devices based on DNA biopolymers, being environmentally friendly, are therefore very interesting from the point of view of applications. In this paper, we present the results of research on complexes in the powder form based on plasmid DNA (pDNA) and three surfactants with aliphatic chains containing 16 carbon atoms (cetyltrimethylammonium chloride, benzyldimethylhexadecylammonium chloride and hexadecylpyridinium chloride). The X-ray diffraction results indicate a local hexagonal packing of DNA helices in plasmid DNA complexes, resembling the packing for corresponding complexes based on linear DNA. Based on the Fourier-transform infrared spectroscopy results, the DNA conformation in all three complexes was determined as predominantly of A-type. The two relaxation processes revealed by dielectric spectroscopy for all the studied complexes are connected with two different contributions to total conductivity (crystallite part and grain boundaries). The crystallite part (grain interior) was interpreted as an oscillation of the polar surfactant head groups and is dependent on the conformation of the surfactant chain. The influence of the DNA type on the properties of the complexes is discussed, taking into account our previous results for complexes based on linear DNA. We showed that the type of DNA has an impact on the properties of the complexes, which has not been demonstrated so far. It was also found that the layer of pDNA-surfactant complexes can be used as a layer with variable specific electric conductivity by selecting the frequency, which is interesting from an application point of view.

8.
Int J Pharm ; 661: 124312, 2024 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-38876441

RESUMO

HYPOTHESIS: Sildenafil base and bosentan monohydrate are co-administered in a chronic therapy of pulmonary arterial hypertension (PAH). Both drugs are poorly soluble in water, and their bioavailability is limited to ca. 50 %. Since bosentan is a weak acid, whereas sildenafil is a weak base, we assumed that their co-amorphization could: (i) improve their solubility in the gastrointestinal fluids, (ii) enable to reach supersaturation and (iii) ensure stabilization of supersaturated solutions. If successful, this could accelerate the development of new fixed-dose combination drugs. EXPERIMENTS: The co-amorphous formulations were prepared using high energy ball milling. Their solid state properties were assessed using XRD, DSC, FT-MIR, and dielectric spectroscopy. Particle size distribution and surface wetting were also analyzed. Polarizing optical microscopy and scanning electron microscopy were applied to assess the microstructure of these powders. A new HPLC-DAD method was developed for a simultaneous quantification of both drugs. FINDINGS: It was shown that binary formulations in which bosentan was molecularly dispersed in sildenafil base (Tg = 64-78 °C) could be manufactured in the high energy ball milling process. When the sildenafil load was below 50 wt. %, the formulations showed the greatest thermal stability and formed long-lasting bosentan supersaturation in PBS.

9.
Materials (Basel) ; 17(8)2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38673266

RESUMO

This paper proposes molecular and supramolecular concepts for potential application in perovskite solar cells. New air-stable symmetrical imine, with thiadiazole moieties PPL2: (5E,6E)-N2,N5-bis(4-(diphenylamino)benzylidene)-1,3,4-thiadiazole-2,5-diamine), as a hole-transporting material was synthesised in a single-step reaction, starting with commercially available and relatively inexpensive reagents, resulting in a reduction in the cost of the final product compared to Spiro-OMeTAD. Moreover, camphorsulfonic acid (CSA) in both enantiomeric forms was used to change the HOMO-LUMO levels and electric properties of the investigated imine-forming complexes. Electric, optical, thermal, and structural studies of the imine and its complexes with CSA were carried out to characterise the new material. Imine and imine/CSA complexes were also characterised in depth by the proton Nuclear Magnetic Resonance 1H NMR method. The position of nitrogen in the thidiazole ring influences the basicity of donor centres, which results in protonation in the imine bond. Simple devices of ITO/imine (with or without CSA(-) or CSA(+))/Ag/ITO architecture were constructed, and a thermographic camera was used to find the defects in the created devices. Electric behaviour was also studied to demonstrate conductivity properties under the forward current. Finally, the electrical properties of imine and its protonated form with CSA were compared with Spiro-OMeTAD. In general, the analysis of thermal images showed a very similar response of the samples to the applied potential in terms of the homogeneity of the formed organic layer. The TGA analysis showed that the investigated imine exhibits good thermal stability in air and argon atmospheres.

10.
RSC Adv ; 13(6): 3792-3806, 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36756553

RESUMO

The aim of the study was to investigate the influence of the environment's pH on the degradation of the layers of the ternary composite l,d-PLA : 5CB : SWCN (10 : 1 : 0.5, w/w/w), where l,d-PLA (poly(lactic acid)) is a biodegradable polymer, 5CB is a well-known liquid crystal (4'-pentyl-4-biphenylcarbonitrile), and SWCN are single-walled carbon nanotubes. For this purpose, the samples were stored in air, distilled water, and solutions of 0.1 M NaOH and 0.1 M HCl, for up to 62 days. Using differential scanning calorimetry, atomic force microscopy, and infra-red spectroscopy methods it was observed that for both neat l,d-PLA and composite layers there was a poor degradation process after the storage under standard air conditions, distilled water, and 0.1 M HCl solution, while the erosion of the surface layer kept in 0.1 M NaOH solution was revealed just after 6 days. The longer storage in 0.1 M NaOH solution resulted in complete degradation of the l,d-PLA polymer layer, while the composite layer survived for up to 62 days. The solubilization of the polymeric l,d-PLA matrix in the composite after 62 days was so severe that it resulted in the vanishing of thermal effects on the DSC curve except for one that was probably connected with the glass transition of the residual quantity of the polymer that remained in the layer or the isotropisation of 5CB. As a result, we have shown that admixtures of 5CB and SWCN accelerate the degradation of l,d-PLA in the composite layer due to the hydrophilic/hydrophobic interface in the layer and act as plasticizers. The mechanism of the degradation process is also discussed.

11.
Ann Agric Environ Med ; 30(4): 773-778, 2023 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-38153084

RESUMO

A genetic disorder caused by the microdeletion of the long arm of 22th chromosome is the most common microdeletion syndrome in humans. It is estimated that 22q11.2 deletion affects one in every 1,000 foetales and one in 4,000 live births. During the neonatal period, the 22q11.2 deletion syndrome manifests itself in children in the form of dysmorphic facial features, and the results of ultrasound imaging tests reveal thymus hypoplasia, urinary tract disorders or brain impairments. The picture is completed by congenital heart diseases which indicate a high probability of the syndrome. This report describes four cases of newborns with 22q11.2 syndrome, presenting with a variety of clinical findings typical for this genetic disorder. The patients present symptoms ranging from mild to life-threatening conditions. The severity of the congenital heart defect determines the survival rate in infancy. Each needs of each patient must be tailored to his or her specific medical problems. A holistic approach, addressing medical and behavioural needs, can be very helpful.


Assuntos
Síndrome de DiGeorge , Cardiopatias Congênitas , Humanos , Criança , Masculino , Recém-Nascido , Feminino , Síndrome de DiGeorge/diagnóstico , Síndrome de DiGeorge/genética , Deleção Cromossômica , Encéfalo
12.
Sci Rep ; 13(1): 13240, 2023 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-37580390

RESUMO

Due to its high electron affinity and electron mobility in a wide absorption range of the visible solar spectrum, [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) is often used as an efficient acceptor in organic photovoltaics. In turn, imines are additives to the active layer of organic solar cells, mainly due to the free electron pair of the imine nitrogen atom and the presence of various chemical groups affecting the polarity and conformations of molecules. However, the attainable efficiency is not as high as expected. Therefore, we have systematically investigated two imines and their mixtures with PC71BM by spectroscopic (the high pressure UV-Vis and frequency domain dielectric), thermoelectric, and mechanical methods for organic, flexible photovoltaics. Both the imines, (N,N'E,N,N'E)-N,N'-([2,2':5',2"-terthiophene]-5,5"-diylbis(methanylylidene))bis(benzo[d]thiazol-2-imine) (SC3) and (6E)-N-((5-(5-(5-((E)-(4-(4-(4-fluorophenyl)thiazol-2-yl)phenylimino)methyl)thiophen-2-yl)thiophen-2-yl)thiophen-2-yl)methylene)-4-(4-(4-fluorophenyl)thiazol-2-yl)benzenamine (SC13), have the same core composed of three thiophene rings but different terminal chains of the molecules. In the imine SC3, the imine bond is followed by benzothiazole rings on both sides of the core, while in SC13, a thiazole ring separates two benzene rings, the terminal one F-substituted. The difference in molecular structure affects the electric properties of the neat imine and its mixed layers. An addition of PC71BM to the imines improves their electric conductivity. The mechanical studies focused on the stress at break and elongation showed superior behaviour compared to fullerene derivative. High pressure systematically reduces the band gap energy, Eg, from 1.68 eV at 0.16 GPa to 1.51 eV at 2.69 GPa for PC71BM, from 1.77 eV at 0.1 MPa to 1.53 eV at 4.15 GPa for SC3, and from 1.99 eV at 0.11 GPa to 1.8 eV at 3.10 GPa for SC13, as determined by the UV-Vis absorbance measurements in a diamond-anvil cell. These Eg reductions reflect the compressed intermolecular interactions that can be used to monitor the structural stability of these compounds. Based on the dielectric studies it was found that the relaxation processes registered for both imines are probably the grain boundary relaxation. Two processes also appear in the systems with PC71BM, but none of them is the one characteristic of imines. The high-frequency process has a dipole character while the low-frequency one is probably the grain boundary relaxation of these systems. The mechanism of quasi-DC conduction in various temperature ranges in the studied systems was also determined.

13.
Ginekol Pol ; 2023 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-37548498

RESUMO

OBJECTIVES: The ideal option of food for a newborn's nourishment has traditionally been human breast milk (HBM). Previous studies have demonstrated a connection between the length of exclusively breastfeeding and its preventive effects on several conditions in neonates. Considering the significance of HBM, the study aimed at detecting the expression of microRNA (miR126*, miR155, miR21, and miR29a) in the breast milk cell fraction of women with hypertension. This was a cohort study of 35 postpartum women. MATERIAL AND METHODS: Five ml of milk was collected into a sterile container from patients in the morning on the second and third days after the labor. The collected milk has been centrifuged, total cellular RNA has been isolated from cell fraction from the collected milk, isolated RNA has been subject to qualitative and quantitative analysis, next reverse transcription has been conducted, followed by that, evaluation of the expression of the selected microRNA has been conducted using the synthesized cDNA. Finally, the tested microRNA's relative expression level has been calculated. RESULTS: Among patients with hypertension, the analysis of cell fraction of breast milk reported lower mean expression of miR126*, miR155, miR21, and miR29a as compared to patients without hypertension. Strong and very strong positive correlation between the expression of miR126* and miR155, miR126* and miR21, miR155 and miR21, miR 155 and miR29a, and miR 21 and miR29a have been noted. CONCLUSIONS: Comparing patients with and without hypertension, it has been noted that patients with hypertension had lower mean expression of miR126*, miR155, miR21, and miR29a.

14.
Phys Rev E ; 105(2-1): 024705, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35291092

RESUMO

Vitrification of the antiferroelectric smectic-C_{A}^{*} phase is reported for the orthoconic mixture W-1000 and its new derivative W-356. The crystallization is not observed even upon slow cooling and the cold crystallization on subsequent heating is also absent. Molecular dynamics in the smectic phases of both mixtures is investigated down to 173 K and the fragility parameters are determined from the temperature behavior of the α-process. X-ray diffraction is applied to compare the structural parameters of W-356 and W-1000 as well as to study the structural changes during the glass transition of the Sm-C_{A}^{*} phase. The evolution of the smectic layer order within the Sm-C_{A}^{*} glass is reported, while the correlation length of the short-range order in the smectic layers is shown to be almost constant below the glass transition temperature. Electrooptic properties of W-356: spontaneous polarization, tilt angle and switching time are determined and compared with these of W-1000. The observed differences between the properties of W-356 and W-1000 might be explained by the dimer formation of components with the -C≡N terminal group, present only in the W-356 mixture, and by the different structure of the aromatic molecular core in one of the W-356 components.

15.
Materials (Basel) ; 14(7)2021 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-33807388

RESUMO

The main goal of this paper was to study the dielectric properties of hybrid binary and ternary composites based on biodegradable polymer Ecoflex®, single walled carbon nanotubes (SWCN), and liquid crystalline 4'-pentyl-4-biphenylcarbonitrile (5CB) compound. The obtained results were compared with other created analogically to Ecoflex®, hybrid layers based on biodegradable polymers such as L,D-polylactide (L,D-PLA) and polycaprolactone (PCL). Frequency domain dielectric spectroscopy (FDDS) results were analyzed taking into consideration the amount of SWCN, frequency, and temperature. For pure Ecoflex®, two relaxation processes (α and ß) were identified. It was shown that the SWCN admixture (in the weight ratio 10:0.01) did not change the properties of the Ecoflex® layer, while in the case of PCL and L,D-PLA, the layers became conductive. The dielectric constant increased with an increase in the content of SWCN in the Ecoflex® matrix and the conductive behavior was not visible, even for the greatest concentration (10:0.06 weight ratio). In the case of the Ecoflex® polymer matrix, the conduction relaxation process at a frequency ca. several kilohertz appeared and became stronger with an increase in the SWCN admixture in the matrix. Addition of oleic acid to the polymer matrix had a smaller effect on the increase in the dielectric response than the addition of liquid crystal 5CB. Fourier transform infrared (FTIR) results revealed that the molecular structure and chemical character of the Ecoflex® and PCL matrixes remained unchanged upon the addition of SWCN or 5CB in a weight ratio of 10:0.01 and 10:1, respectively, while molecular interactions appeared between L,D-PLA and 5CB. Moreover, adding oleic acid to pure Ecoflex® as well as the binary and ternary hybrid layers with SWCN and/or 5CB in a weight ratio of Ecoflex®:oleic acid equal to 10:0.3 did not have an influence on the chemical bonding of these materials.

16.
Materials (Basel) ; 14(16)2021 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-34443243

RESUMO

The aim of this paper is to show, by systematic studies, the influence of γ-Fe2O3 nanoparticles on the physical parameters of the liquid crystalline matrix, exhibiting a ferroelectric phase in a wide temperature range. The detailed research was carried out by using diffraction (PXRD), microscopic (OM, SEM, FCPM, POM), thermal (DSC), optical (TLI), electric and spectroscopic (FTIR) methods. We show that even the smallest concentration of γ-Fe2O3 nanoparticles largely modifies the parameters of the ferroelectric SmC* phase, such as spontaneous polarization, switching time, tilt angle, rotational viscosity, dispersion anchoring energy coefficient and helix pitch. The admixture also causes a significant reduction in the temperature of phase transitions, broadening the SmA* phase at the expense of the SmC* phase and strong streaking of the texture. We present and explain the non-monotonic modification of these parameters with an increase in the nanoparticle concentration. The influence of oleic acid admixture on these parameters is also widely discussed. We have shown that certain parameters of organic-metal nanocomposites can be controlled by the appropriate amount of metal admixture.

17.
Materials (Basel) ; 13(11)2020 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-32486053

RESUMO

The main goal of this paper was to study the optical, electrical, and thermal properties of hybrid composites based on biodegradable polymers (L,D-poly(lactic acid), polycaprolactone or Ecoflex®), single walled carbon nanotubes (SWCN), and 4'-pentyl-4-biphenylcarbonitrile (5CB). The biodegradable polymers' binary and ternary compositions were analyzed in detail by ultraviolet and visible (UV-Vis) spectroscopy taking into consideration their chemical structure and interactions with 5CB and SWCN. Differential scanning calorimetry (DSC) studies of the created hybrid layers showed thermal stability and changes in glass transition temperature and melting point in comparison to neat polymers, depending on the chemical structure of the polymer used and the type of composition. Morphology of the created layers were investigated by atomic force and polarizing microscopy. The static contact angle measurements of a water drop showed that all of the neat polymer layers were hydrophobic with angle values ranging from 108° to 115°. In addition, in the case of the Ecoflex layers, both with and without additives, a rapid sorption of the deposited water drop was observed. Finally, a simple device with poly(ethylene terephthalate) (PET)/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly [[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl ]] (PTB7) : [6,6]-phenyl-C71-butyric acid methyl ester (PC70BM)/Ag/biodegradable polymer:SWCN architecture was constructed and tested using an infrared (IR) thermographic camera to investigate the surface defects on the created hybrid layers. Increasing the SWCN admixture from 0.01 to 0.5% significantly improved the conductivity only in the case of L,D-poly(lactic acid):SWCN (10:0.5), for which above 5 V, a current with a resistance of 3030.7 Ω could be measured. In order to use the created layers as flexible electrodes, the first experiments were carried out with an admixture of SWCN and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) as conductive compounds.

18.
J Phys Chem B ; 124(28): 6055-6073, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32569472

RESUMO

In this paper, for the first time, the influence of the BaTiO3 particles on the antiferroelectric liquid crystalline phase was shown. Low concentrations and two different sizes of BaTiO3 particles (nano- and submicroparticles) were used. It was found that admixture of the ferroelectric particles causes a decrease in the concentration of free ions in the liquid crystal matrix. Despite the small amount of admixture, a decrease in spontaneous polarization, switching time and rotational viscosity, was observed, while the tilt angle of molecules and the smectic layer thickness did not change. It turns out that BaTiO3 particles have a very large impact on the dielectric spectra not only in the antiferroelectric phase but also in the ferroelectric and paraelectric phases of the polymorphic mixture studied. The dopants affect also the complex conductivity. In this paper, we explain why some properties are modified by BaTiO3 particles and others are not.

19.
Ital J Pediatr ; 46(1): 125, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32894158

RESUMO

BACKGROUND: Bleedings are more frequent in the population of preterm children than among those born at term, much less in older children. The reasons for such bleedings in preterms include plasma factor deficiencies, immaturity of small vessels in the germinal matrix region, prenatal hypoxia or sepsis. They affect the brain tissue, the gastrointestinal tract and the respiratory system, or are manifested by prolonged bleedings from injection sites. Haemophilia is a rare cause of haemorrhages in the neonatal period, and in the female population it is even seen as an extremely rare disorder. Its aetiology in girls is diverse: inheriting defective genes from their parents, skewed X inactivation or a single X chromosome. CASE PRESENTATION: The article presents a case of a preterm girl born in the 28th week of pregnancy, who was diagnosed with severe haemophilia A stemming from the absence of the X chromosome. The girl's father is healthy, but her mother's brother suffers from haemophilia. On the second day of the child's life, a prolonged bleeding from the injection site was observed. A coagulation profile revealed prolonged APTT which pointed to haemophilia A diagnosis. Moreover, a marked clinical dysmorphy, female sex and a negative family history on the father's side led the treating team to extend the diagnostic procedures to encompass karyotype evaluation. The girl was diagnosed with Turner syndrome. No bleeding to the central nervous system was observed during her hospital stay. CONCLUSIONS: Preterm children belong to the risk group of bleeding into the central nervous system or haemorrhages in the course of sepsis. Rare causes of such bleedings should also be borne in mind, including haemophilia. The initial symptoms of haemophilia in preterm children occur in the first days of their lives, which is connected with a number of invasive procedures required in that period. Genetic conditions may coexist with one another. Arriving at one diagnosis does not mean one should abandon further diagnostic procedures in cases where additional atypical symptoms are present which do not match the clinical image of a primary disease.


Assuntos
Hemofilia A/complicações , Hemofilia A/diagnóstico , Doenças do Prematuro/diagnóstico , Síndrome de Turner/complicações , Síndrome de Turner/diagnóstico , Feminino , Humanos , Recém-Nascido , Recém-Nascido Prematuro
20.
Acta Crystallogr B Struct Sci Cryst Eng Mater ; 76(Pt 6): 1128-1135, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33289724

RESUMO

Structural characteristics of solid and liquid crystalline phases of 7OS5 (4-n-pentylphenyl-4'-n-heptyloxythiobenzoate), the achiral smectogenic mesogen with the shortest terminal carbon chain in the nOS5 homologous series, are studied by complementary methods. Simultaneously perfomed X-ray diffraction and differential scanning calorimetry occur to be a powerful tool to study metastable phases. The single crystal structure of a high-temperature phase, supercooled from the room temperature down to -183°C [orthorhombic crystal system; space group Pca21; a = 54.285 (5) Å, b = 5.5843 (3) Å, c = 14.841 (1) Å, Z = 8] is determined. Lamellar ordering of elongated molecules is stabilized by hydrogen bonds . Temperature dependence of unit-cell parameters in two crystal phases as well as structural parameters of liquid crystalline phases (smectic layer spacing, tilt angle, average distance between the long axes of molecules and correlation lengths) are determined by X-ray diffraction. The obtained results are compared with the data available for other compounds in the nOS5 homologous series.

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