Understanding structure-properties relationships of porphyrin linked to graphene oxide through π-π-stacking or covalent amide bonds.

Two graphene oxide nanoassemblies using 5-(4-(aminophenyl)-10,15,20-triphenylporphyrin (TPPNH2) were fabricated by two synthetic methods: covalent (GO-CONHTPP) and noncovalent bonding. GO-CONHTPP was achieved through amide formation at the periphery of GO sheets and the hybrid material was fully characterized by FTIR, XPS, Raman spectroscopy, and SEM. Spectroscopic measurements together with theoretical calculations demonstrated that assembling TPPNH2 on the GO surface in DMF-H2O (1:2, v/v) via non-covalent interactions causes changes in the absorption spectra of porphyrin, as well as efficient quenching of its emission. Interestingly, covalent binding to GO does not affect notably neither the porphyrin absorption nor its fluorescence. Theoretical calculations indicates that close proximity and π-π-stacking of the porphyrin molecule with the GO sheet is possible only for the non-covalent functionalization. Femtosecond pump-probe experiments revealed that only the non-covalent assembly of TPPNH2 and GO enhances the efficiency of the photoinduced electron transfer from porphyrin to GO. In contrast to the non-covalent hybrid, the covalent GO-CONHTPP material can generate singlet oxygen with quantum yields efficiency (ΦΔ = 0.20) comparable to that of free TPPNH2 (ΦΔ = 0.26), indicating the possible use of covalent hybrid materials in photodynamic/photothermal therapy. The spectroscopic studies combined with detailed quantum-chemical analysis provide invaluable information that can guide the fabrication of hybrid materials with desired properties for specific applications.

Aromatic fluorocopolymers based on α-(difluoromethyl)styrene and styrene: synthesis, characterization, and thermal and surface properties.

A study on the α-(difluoromethyl)styrene (DFMST) reactivity under conventional radical copolymerization conditions is presented. Although the homopolymerization of DFMST failed, its radical bulk copolymerization with styrene (ST) led to the synthesis of fluorinated aromatic polymers (FAPs). The resulting novel poly(DFMST-co-ST) copolymers were characterized by 1H, 19F and 13C NMR spectroscopies that evidenced the successful incorporation of DFMST units into copolymers and enabled the assessment of their respective molar percentages (10.4-48.2 mol%). The molar masses were in the range of 1900-17 200 g mol-1. The bulkier CF2H group in the α-position induced the lower reactivity of the DFMST comonomer. ST and DFMST monomer reactivity ratios (r DFMST = 0.0 and r ST = 0.70 ± 0.05 at 70 °C) were determined based on linear least-square methods. These values indicate that DFMST monomer is less reactive than ST, retards the polymerization rate, and thus reduces the molar masses. Moreover, the thermal properties (T g, T d) of the resulting copolymers indicate that the presence of DFMST units incorporated into poly(ST) structure promotes an increase of the T g values up to 109 °C and a slightly better thermal stability than that of poly(ST). Additionally, the thermal decomposition of poly(DFMST-co-ST) copolymer (10.4/89.6) was assessed by simultaneous thermal analysis coupled with Fourier-transform infrared spectroscopy and thermogravimetric analysis coupled with mass spectrometry showing that H2O, CO2, CO and styrene were released. The surface analysis was focused on the effects of the -CF2H group at the α-position of styrene comonomers on surface free energy of the copolymer films. Water and diiodomethane contact angle (CA) measurements confirmed that these copolymers (M n = 2300-17 200 g mol-1) are not exactly the same as polystyrenes (M n = 2100-21 600 g mol-1) in the solid state. The CA hysteresis for poly(ST) (6-8°) and poly(DFMST-co-ST) copolymers (3-5°) reflected these differences even more accurately.

Thionine-graphene oxide covalent hybrid and its interaction with light.

Graphene oxide sheets (GO) were covalently functionalized with thionine molecules. The obtained hybrid material, Th-GO, was characterized by means of scanning electron microscopy (SEM), Auger electron spectroscopy (AES), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. Subsequently, the interaction of light with the free dye molecules and with dye molecules bound to the graphene oxide sheets was probed via UV-Vis spectroscopy, fluorescence spectroscopy and femtosecond pump-probe spectroscopy. The experimental results proved that thionine was successfully grafted onto the GO sheets, however, only one of the two amino groups of thionine was always involved in the amide bond formation. The Th-GO hybrid suspended in N,N-dimethylformamide (DMF) exhibited suppressed fluorescence as compared to the free dye in the same solvent, pointing to an efficient interaction between the photoexcited dye and the graphene sheets. Yet, no electron transfer products were detected by transient absorption measurements, even though there was a shortening of the singlet excited state lifetime of thionine (from the 567 ps for the free dye to the 313 ps for the dye in Th-GO). These results can be rationalized in terms of a fast back electron transfer process or possibly an energy transfer process.

A comparison of cephalometric analysis using radiographs and craniofacial computed tomography in patients with obstructive sleep apnea syndrome: preliminary report.

The aim of this study was to describe the similarities and differences as well as the convenience in using of cephalometric radiographs and craniofacial computed tomography in obstructive sleep apnea syndrome (OSAS) patients and to demonstrate the relationship between the severity of sleep-disordered breathing and severity of cephalometric abnormalities. A total of 28 randomly selected patients with snoring, and varying degrees of sleep-disordered breathing were included in this study. A control group included 22 patients. These patients had no snoring or clinical evidence of sleep-disordered breathing as evaluated by polysomnographic test. No patients had prior pharyngeal or maxillomandibular surgery. All patients were evaluated by otolaryngological examination and had polysomnography, cephalometric radiographs and craniofacial CT scans. In study group the evaluation between cephalometric analysis on radiographs and CT scans was made. The comparison between the control and the study group was also assessed as far as cephalometric data are concerned. The cephalometric parameters revealed major differences between controls and patients with OSAS regarding the size and position of soft palate and uvula, volume and position of tongue, hyoid position, mandibulo-maxillary protrusion and size of the pharyngeal airway space. OSAS is associated with statistically significant changes in cephalometric measurements. Lateral cephalometric analysis and craniofacial CT scans add further information to the anatomical assessment of patients with OSAS. We found craniofacial CT scan measurements to be easier and more accurate especially when applying to soft tissues. We believe that this method may also be useful for patient classification to surgical procedures.

[Precocious puberty due to hypothalamic hamartoma]. / Przedwczesne dojrzewanie plciowe w przebiegu guza hamartoma podwzgórza.

INTRODUCTION: Central precocious puberty is usually idiopathic. Appearance of the precocious puberty symptoms in early childhood or pre-school period indicate that also it could be caused by organic disorder of the central nervous system. The aim of this work is to present the case of the 4-year-old girl, diagnosed with precocious puberty. THE CASE REPORT: The first clinical symptoms of precocious puberty such as increased growth rate and breast enlargement were observed when the girl was 4 years old. The height (above the 97 centile) and weight (90-97 centile) were measured during the physical examination. The advancement of sexual features was determined as follows: thelarche III degrees , pubarche II degrees , axillarche II degrees . The LHRH test used in this differential diagnosis revealed the pubertal level of gonadotropins, when plasma levels of dehydroepiandrosterone, prolactin, thyroid-stimulating hormone and alpha-fetoprotein levels were correct. The advanced bone age was 8 years and 10 months, while the height age was 7 years. The final diagnosis was based on MRI scan. The patient is currently treated with an analog of gonadoliberine (Diphereline). In conclusion, we aspired to notice that the pharmacological treatment of hypothalamic hamartoma may be safe and effective. Suppression of puberty to the normal time of pubescence gives a child the chance to reduce health discomforts as well as further emotional and social problems.