Soft modes of the dielectric response in the twist-bend nematic phase and identification of the transition to a nematic splay bend phase in the CBC7CB dimer.

The dielectric spectra of the twist-bend nematic phase (NTB) of (the bent-shaped) achiral liquid-crystal dimer 1''-,7''-bis(4-cyanobiphenyl-4'-yl)heptane (CB7CB) are studied for the determination of the different relaxation modes. Two molecular processes and one collective process were observed in the megahertz frequency range. Two molecular processes were assigned: one to the precessional rotation of the longitudinal components of the cyanobiphenyl groups and the second one to the spinning rotation of the transverse component of the CB7CB dimer. The peak, at a frequency of about 1 MHz, shows a peculiar temperature behavior at the NTB to N transition, reminiscent of the soft mode at the transition from the SmA to the SmC phase. This peak can be assigned to a collective fluctuation of the tilt angle of the coarse grained director N with respect to the pseudo-layer normal. This corresponds well with the electro-clinic effect observed as a response to an electric field in electro-optic experiments. The low frequency relaxation process, observed in the frequency range of 1 Hz-102 Hz can be identified as a Goldstone mode, related to long-scale fluctuation of the cone phase. The frequency drop of the mode on increasing the bias field is interpreted as unwinding of a helix and an indication of the formation of a field induced nematic splay bend phase (NSB). This finding is also confirmed by birefringence data in the presence of strong bias fields.

Assessment of the bacterial viability of chlorine- and quaternary ammonium compounds-treated Lactobacillus cells via a multi-method approach.

AIMS: The assessment of the bacterial viability of chlorine- and quaternary ammonium compounds (QACs)-treated Lactobacillus cells by culture-dependent and -independent methods. METHODS AND RESULTS: Lactobacillus isolates (Lactobacillus plantarum G1, Lactobacillus plantarum B1, Lactobacillus brevis S1 and Lactobacillus paracasei W1) in biofilm and planktonic cell suspensions were treated with chlorine-based (0·018 and 0·18%) and QACs-based (0·2 and 2·0%) disinfectants for 5 min and then analysed by plate counting, flow cytometry (FCM) and fluorescence activated cell sorting (FACS). The reaction of sessile cells to disinfectants was assessed with the confocal laser scanning microscopy (CLSM). Plate counts revealed L. paracasei W1 to be substantially inactivated by both disinfectants, while counts of the other isolates to be significantly reduced only by QACs, with L. plantarum B1 and L. brevis S1 showing a greater difference between QACs concentrations and cell types. In several cases, the disinfectants caused slightly higher inactivation of planktonic than biofilm cells, with L. plantarum B1 being significantly less sensitive to QACs in biofilm cells (P < 0·05). Following FCM with a Syto® 9/PI assay, which addresses cell membrane integrity, the emergence of damaged (Syto® 9- PI+ ) and injured (Syto® 9+ PI+ ) subpopulations was often observed in cells when they were treated with QACs, whereas intact (Syto® 9+ PI- ) and unstained (Syto® 9- PI- ) subpopulations were mostly encountered in chlorine-treated cells. Except Syto® 9- PI+ , all subpopulations were recovered on agar plates following FACS, with biofilm cells showing higher culturability irrespective of conditions, probably because of the residues of the biofilm matrix which serve as a protective cover for the bacteria. The CLSM revealed a substantial cell membrane damage within the QACs-treated biofilms, however, some cells deep in the biofilm were still intact and thus remained protected against this disinfectant. CONCLUSION: We found that FCM/FACS proved useful in the analysis of lactobacilli membrane integrity in disinfection experiments as well as in recovery evaluation of planktonic-biofilm cell subpopulations. In turn, CLSM was particularly useful in investigating the resistance mechanism when Lactobacillus cells were embedded in biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the need for treatment optimization on a case-by-case basis to avoid the emergence of cells in intermediate states with recovery potential and to reach and, thus, kill all bacteria in already developed lactobacilli biofilms.

Molecular orientational distribution function of a chiral de Vries smectic liquid crystal from birefringence measurements.

An alternative method for determining the orientational distribution function and the order parameter from the electric field-induced birefringence measurements of a chiral liquid crystal compound in its Smectic A* is being introduced. A chiral mesogen based on a 5-phenyl-pyrimidine benzoate core terminated by a trisiloxane group on one side and the chiral alkyloxy chain on its opposite side is designed and synthesized to exhibit the "de Vries" smectic characteristics. The compound exhibits first order Smectic A*-Smectic C* phase transition, evidenced by the results of differential scanning calorimetry. The material is being investigated by electro-optical experiment in its smectic phases. We present a model that incorporates the generalised Langevin-Debye model which includes the Maier-Saupe effective mean-field potential term in order to explain the change in birefringence with the electric field. A good agreement between the experimental results and the predictions from the model leads to the determination of the molecular orientational distribution function in Smectic A phase. Furthermore, the temperature dependency of the Saupe orientational order parameter ⟨P2⟩ is obtained using the parameters of the model. Based on the experimental and theoretical results, we show that de Vries Smectic A* phase exhibits a broad volcano-like tilt angle distribution with the two maxima occurring at finite tilt angles closer to the Smectic A*-Smectic C* transition temperature, and a sugarloaf-like distribution occurs in the tilt for temperatures close to the Isotropic-Smectic A* phase transition.

Non-invasive high-intensity focused ultrasound treatment of the placenta: a preliminary in-vivo study using a simian model.

OBJECTIVE: To demonstrate the feasibility and efficacy of high-intensity focused ultrasound (HIFU) for the non-invasive creation of placental lesions in a simian model. METHODS: Eight pregnant monkeys were exposed to HIFU treatment after anesthesia, using a toroidal HIFU 2.5-MHz transducer with an integrated ultrasound imaging probe. Lesions on the placental tissue were created non-invasively by placing the HIFU probe on the skin surface. Fetal and maternal parameters, such as maternal heart rate, fetal heart rate and subcutaneous and intra-amniotic fluid temperature, were recorded during HIFU exposure. Cesarean section was performed immediately after the procedure to extract the placenta and examine the fetus and the maternal abdominal cavity. Placental HIFU lesions were assessed by ultrasound, gross pathology and histology. RESULTS: The mean gestational age of the monkeys was 72 ± 4 days. In total, 13 HIFU procedures were performed. The acoustic power and exposure time were increased progressively. This gradual increase in total energy delivered was used to determine a set of parameters to create reproducible lesions in the placenta without complications. Five placental lesions were observed with average diameters of 6.4 ± 0.5 mm and 7.8 ± 0.7 mm and an average depth of 3.8 ± 1.5 mm. Ultrasound examination of the placentae revealed hyperechoic regions that correlated well with macroscopic analysis of the HIFU lesions. Necrosis of placental tissue exposed to HIFU was confirmed with macroscopic and microscopic analysis. There was no significant variation in maternal and fetal parameters during HIFU exposure. CONCLUSIONS: This study demonstrates the feasibility of HIFU applied non-invasively to the placental unit in an in-vivo pregnant monkey model. The technique is safe in the immediate short term and is potentially translatable to human pregnancy. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Observation of the de Vries behavior in SmA* phase of a liquid crystal using polarised Raman scattering and infrared spectroscopy.

Two approaches exist in the literature for describing the orientational distribution function (ODF) of the molecular directors in SmA* phase of liquid crystals, though several models are recently proposed in the literature for explaining the de Vries behaviour. These ODFs correspond to either the conventional unimodal arrangements of molecular directors arising from the mean field theory that leads to the broad or sugar-loaf like distribution or to the "diffuse-cone-shaped" type distribution proposed by de Vries. The hypothesis by de Vries provides for a realistic explanation as to how at a molecular level, a first-order SmA* to SmC* transition can occur where the uniform molecular director azimuthal distributions condense to values lying within a narrow range of angles; finally these condense to a single value while at the same time ensuring a little or no concomitant shrinkage in the layer spacing. The azimuthal distribution of the in-layer directors is probed using IR and polarized Raman spectroscopic techniques. The latter allows us to obtain the ODF and the various order parameters for the uniaxial and the biaxial phases. Based on the results of these measurements, we conclude that the "cone-shaped" (or volcano-shaped) de Vries type of distribution can most preferably describe SmA* where "a first-order phase transition from SmA* to SmC*" and a low layer shrinkage can both be easily explained.

High-intensity focused ultrasound applied to the placenta using a toroidal transducer: a preliminary ex-vivo study.

OBJECTIVE: To demonstrate in an ex-vivo model the feasibility of applying high-intensity focused ultrasound (HIFU) using a toroidal transducer for the creation of placental lesions. METHODS: In this study we used a toroidal transducer, composed of 32 ring-shaped emitters with an ultrasound probe at the center, operating at a frequency of 2.5 MHz. We examined 45 human placentae, following either normal vaginal delivery or medical termination of pregnancy between 17 and 40 gestational weeks. First, the attenuation coefficients of 12 human placentae were measured and integrated into a numerical model for simulating HIFU lesions. Then, using acoustic parameters from this preliminary study, we performed ex-vivo experiments with 33 human placentae, each overlain with an animal abdominal wall to simulate the maternal wall. We created single HIFU lesions in 25 of these placentae, and a series of six juxtaposed lesions in eight, studying these both sonographically and macroscopically. RESULTS: Human placental attenuation coefficients of the 12 human placentae ranged from 0.072 to 0.098 Np/cm/MHz, according to gestational age. The 25 single HIFU lesions created had an average diameter of 7.1 ± 3.2 mm and an average depth of 8.2 ± 3.1 mm. The average diameter of the eight series of six juxtaposed HIFU lesions was 23.0 ± 5.0 mm and the average depth was 11.0 ± 4.7 mm. The average thickness of the abdominal walls was 10.5 ± 1.8 mm. No lesions or damage were observed in intervening tissues. CONCLUSION: This study demonstrates, using an ex-vivo model, the feasibility, reproducibility, harmlessness and effectiveness of HIFU applied to the human placenta.

Molecular dynamics of itraconazole at ambient and high pressure.

Comprehensive molecular dynamics studies of vitrified and cryogrounded itraconazole (Itr) were performed at ambient and elevated pressure. DSC measurements yielded besides melting and glass transition observed during heating and cooling of both samples two further endothermic events at around T = 363 K and T = 346 K. The nature of these transitions was investigated using X-ray diffraction, broadband dielectric spectroscopy and Density Functional Theory calculations. The X-ray measurements indicated that extra ordering in itraconazole is likely to occur. Based on calculations and theory derived by Letz et al. the transition observed at T = 363 K was discussed in the context of formation of the nematic mesophase. In fact, additional FTIR measurements revealed that order parameter variation in Itr shows a typical sequence of liquid crystal phases with axially symmetric orientational order; i.e. a nematic phase in the temperature range 361.7 K to 346.5 K and a smectic A phase below 346.5. Moreover, dielectric measurements demonstrated that except for the structural relaxation process, there is also slower mode above the glass transition temperature in both vitrified and cryogrounded samples. We considered the origin of this mode taking into account DFT calculations, rod like shape of itraconazole and distribution of its dipole moment vectors. For the dielectric data collected at elevated pressure, evolution of the steepness index versus pressure was determined. Finally, the pressure coefficient of the glass transition temperature was evaluated to be equal to 190 K GPa(-1).

Oncological outcome of primary versus secondary muscle-invasive bladder cancer is comparable after radical cystectomy.

BACKGROUND: High-risk non-muscle-invasive bladder cancer (NMIBC) progressing to muscle-invasive bladder cancer (MIBC) is associated with adverse tumour biology. It is unclear, however, whether outcome of NMIBC progressing to MIBC is adverse compared to primary MIBC and whether NMIBC of higher risk of progression to MIBC is adverse compared to NMIBC of lower risk. OBJECTIVE: Our objective was to assess cancer-specific survival (CSS) following radical cystectomy (RC) for primary MIBC and for NMIBC progressing to MIBC in dependence of EORTC risk score. MATERIALS AND METHODS: Clinical and histopathological characteristics and CSS of 150 patients were assessed. Secondary MIBCs were stratified by EORTC risk score at the last transurethral resection of bladder tumour for NMIBC. RESULTS: CSS did not differ significantly between primary and secondary MIBC (p = 0.521). Secondary MIBC with high EORTC score had significantly shorter CSS compared to secondary MIBC with intermediate EORTC score (p = 0.029). In multivariable analysis, pathological tumour stage (HR = 3.77; p = 0.020) and lymph node stage (HR = 2.34; p = 0.022) were significantly correlated with CSS. CONCLUSION: While the outcome of secondary MIBC is not generally adverse compared to primary MIBC, the EORTC risk score not only reflects high risk of progression of NMIBC to MIBC, but also worse outcome following RC for secondary MIBC. Timely RC should thus be debated in high-risk NMIBC.

Biaxial order and a rotation of the minor director in the nematic phase of an organo-siloxane tetrapode by the electric field.

Biaxiality in the nematic phase for a liquid crystalline tetrapode made up of organo-siloxanes mesogens is investigated using polarized infrared spectroscopy. An ordering of the minor director for the homeotropically aligned sample is found to depend on the amplitude of the in-plane electric field. On increasing the in-plane electric field, the minor director, lying initially along the rubbing direction, rotates to the direction of the applied field. The scalar order parameters of the second rank tensor are found to depend significantly on the strength of the electric field. A most significant increase is found in the nematic order parameter and in the parameter that characterizes the phase biaxiality.

Broadband-dielectric-spectroscopy study of molecular dynamics in a mixture of itraconazole and glycerol in glassy, smectic-A, and isotropic phases.

Itraconazole (ITZ) is a thermotropic liquid crystal that exhibits isotropic, nematic, and smectic phases on cooling towards the glass transition upon melting. Over the years, new aspects regarding the liquid-crystalline ordering of this antifungal drug were systematically revealed. It has been shown recently that the temperature range of individual mesophases in ITZ can be modified by adding a small amount of glycerol (GLY). Moreover, above the critical concentration of 5% w/w, a smectic to nematic transition can be avoided. Here we go one step further, and we used broadband dielectric spectroscopy to investigate the new phase behavior of the ITZ-GLY mixture (5% w/w). To confirm the phase transformations of the ITZ-GLY mixture, differential scanning calorimetry was also employed. The analysis of molecular dynamics of the ITZ-GLY mixture in the glassy and isotropic phases revealed features similar to those observed for neat ITZ. Two relaxation processes were identified in the smectic-A phase, with similar temperature dependence, most likely related to the fast rotations around the long axis of a molecule. Additionally, the derivative analysis revealed another low-frequency process hidden under DC conductivity ascribed to the slow rotations about a short axis. We will show that the differences in the molecular organization in the smectic-A and isotropic phases leave a clear fingerprint on the temperature behavior of relaxation times and other dielectric parameters, such as DC conductivity and dielectric strength, for which a pretransition effect has been detected.

[Devastated bladder outlet-suprapubic catheter vs. reconstruction]. / Der zerstörte Blasenauslass ("devastated bladder outlet") ­ suprapubischer Katheter vs. Rekonstruktion.

The combination of a severe urethral sphincter defect with simultaneous development of recurrent bladder outlet obstruction characterizes a "devastated bladder outlet", which often is not surgically reconstructable. Clinically, quality of life is considerably compromised in affected patients with a wide variance of symptoms, mostly complete incontinence, but also urinary retention. This condition is usually preceded by multiple endoscopic interventions or even open surgical procedures, occasionally also in combination with radiotherapy of the pelvic region as part of multimodal oncological therapy. Treatment of these cases is complex and limited to few promising procedures. A potential therapy should primarily include the decision about the possibility of preserving the urinary bladder. In individual cases, this can result in simple therapy options while at the same time maintaining an acceptable quality of life for those affected. If there is no possibility of a refunctionalization of the original bladder, supravesical urinary diversion is indicated as a last-resort therapy. This paper provides a review as well as the limits and possibilities of conservative and surgical treatment options for a devastated bladder outlet.

[Bilateral intrauterine testicular torsion in a mature newborn]. / Bilaterale intrauterine Hodentorsion bei einem reifen Neugeborenen.

Bilateral intrauterine testicular torsion is an extremely rare emergency and can be difficult to diagnose due to its diverse manifestation and potential differential diagnoses. In time surgical intervention is crucial for the retention of testicular function. We present a newborn with a bilateral testicular torsion, in which one testicle could be saved after detorsion. The contralateral side showed hemorrhagic infarction and was removed. Since organ preservation is rarely successful, the surgical therapy is discussed controversially.

Mutational spectrum of the C1INH (SERPING1) gene in patients with hereditary angioedema.

Hereditary angioedema (HAE) is an autosomal dominant disease that manifests as intermittent acute swellings of the skin and mucosal surfaces, which, in the gastrointestinal tract and larynx, may even be fatal. HAE results from functional deficiency of the C1 inhibitor (C1INH) protein, which plays a key role in the classical pathway of complement activation. C1INH is the sole inhibitor of the activated proteases C1r and C1s, and is the major regulator of activated coagulation Factor XII and plasma kallikrein, which limits the generation of the vasoactive peptide bradykinin. In this paper, we report on the genetic analysis of 173 families (including 326 members) with a clinical diagnosis of HAE. Direct sequencing, Southern blotting and quantitative PCR by the MLPA method were used to screen for mutations in C1INH (SERPING1). In 142 families (82.1%), a causative C1INH gene mutation could be identified. A total of 80 novel point mutations of C1INH not published previously were detected in 96 pedigrees (including 172 members). Our results corroborate C1INH (SERPING1) deficiency as a disease of extreme allelic heterogeneity with almost each individual family carrying their own mutation. Routine molecular genetic analysis is an effective way of confirming the clinical diagnosis and identifying mutation carriers early on before any clinical manifestation becomes apparent. It is, therefore, a valuable tool in prevention and adequate treatment of acute and life-threatening oedema.

Distortions in structures of the twist bend nematic phase of a bent-core liquid crystal by the electric field.

The dielectric spectra of the twist bend nematic phase (N_{TB}) of an achiral asymmetric bent-core liquid crystalline compound are studied for determining the various relaxation modes. Dielectric measurements are also carried out under the bias field E up to 8 V/µm. Two molecular and two collective relaxation processes are observed. The orientational order parameters with respect to the local and the main directors determined using molecular modes are used to find the heliconical angle. The results also show that the order parameter with reference to the main director reverses its trend from increasing to decreasing at temperatures of a few degrees above the N_{TB} to N transition. The collective relaxation modes are assigned to (a) distortions of the local director by the electric field at a frequency of ∼100kHz while the periodic helical structure remains unaltered (mode attributed to flexoelectricity); (b) changes in the periodic structure arising from a coupling of the dielectric anisotropy with the electric field at the lowest frequency in the range of 100 Hz-10 kHz. Frequency of the higher frequency collective mode (∼100kHz) depends primarily on the heliconical angle and has anomalous softeninglike behavior at the N-N_{TB} transition. The lowest frequency mode is studied under the bias field E; the modulus of the wave vector gradually vanishes on increasing E (except for an initial behavior, E^{2}<0.1V^{2}/µm^{2}, which is just the opposite). The transition from the twist bend to splay bend structure is observed by a sudden drop in the frequency of this mode, followed by a linear decrease in frequency by increasing E. The results agree with the predictions made from the currently proposed models for a periodically distorted N_{TB} phase.

[Fistulas of the urogenital tract after radiotherapy]. / Fisteln des Urogenitaltraktes nach Strahlentherapie.

BACKGROUND: Radiotherapy plays a substantial role in the treatment of malignancies. More than 2/3 of all oncologic patients undergo radiotherapy during their specific treatment. Besides manifold side effects of radiotherapy, radiogenic fistulas of the urogenital tract are a potential severe complication. These fistulas might affect the female genital tract and the urinary tract. THERAPY: Potential manifold variety of radiogenic urogenital fistulas requires a specific therapy. Radiation tissue damage includes severely disturbed local blood supply. Consequently, in some cases extremely complex reconstructive techniques are necessary to restore the functionality of the urinary tract. CONCLUSION: The treatment of radiogenic urogenital fistulas is challenging. A successful therapy can only be achieved by local improvement of the blood supply in the damaged area.

Phase behavior and characterization of heptamethyltrisiloxane-based de Vries smectic liquid crystal by electro-optics, x rays, and dielectric spectroscopy.

A heptamethyltrisiloxane liquid crystal (LC) exhibiting I-SmA^{*}-SmC^{*} phases has been characterized by calorimetry, polarizing microscopy, x-ray diffraction, electro-optics, and dielectric spectroscopy. Observations of a large electroclinic effect, a large increase in the birefringence (Δn) with electric field, a low shrinkage in the layer thickness (∼1.75%) at 20 °C below the SmA^{*}-SmC^{*} transition, and low values of the reduction factor (∼0.40) suggest that the SmA^{*} phase in this material is of the de Vries type. The reduction factor is a measure of the layer shrinkage in the SmC^{*} phase and it should be zero for an ideal de Vries. Moreover, a decrease in the magnitude of Δn with decreasing temperature indicates the presence of the temperature-dependent tilt angle in the SmA^{*} phase. The electro-optic behavior is explained by the generalized Langevin-Debye model as given by Shen et al. [Y. Shen et al., Phys. Rev. E 88, 062504 (2013)10.1103/PhysRevE.88.062504]. The soft-mode dielectric relaxation strength shows a critical behavior when the system goes from the SmA^{*} to the SmC^{*} phase.

Tannic acid-stabilized pericardium tissue: IR spectroscopy, atomic force microscopy, and dielectric spectroscopy investigations.

Infrared (IR) spectroscopy, atomic force microscopy (AFM), and dielectric spectroscopy methods were employed to study structural and dynamic changes in the tannic acid (TA)-stabilized pericardium tissue. Chemically stabilized pericardium tissue is widely used in construction of the tissue derived bioprostheses. IR spectra recorded in the range 400-4000 cm-1 allowed us to recognize different types of TA-collagen interactions. Formation of hydrogen bonds between amine as well as amide NH groups from collagen and hydroxyl groups of TA was analyzed. The AFM imaging showed that the stabilization procedure with TA introduces considerable changes in both surface topography and thickness of collagen fibrils as well as in fibril arrangement on the tissue surface. It was found, that these structural changes have an impact on the dielectric behavior of the TA-stabilized tissue. The dielectric spectra for the native and TA-stabilized tissues were measured in the frequency and temperature ranges of 10(-1) -10(7) Hz and 120-270 K, respectively. The dielectric spectra revealed the relaxation process due to orientation of bound water supplemented by the fluctuation of collagen polar side groups. At the temperatures above approximately 210 K, the relaxation due to ion migration process was observed. It was found that both relaxation processes were influenced by the TA-collagen interaction.

Orientational order and dynamics of the dendritic liquid crystal organo-siloxane tetrapodes determined using dielectric spectroscopy.

The dielectric measurements have been carried out on the two zeroth generation dendrimers with four branched arms (called tetrapodes) based on the siloxane cores. The results are analyzed in the framework of the molecular theory of dielectric permittivity by Maier and Meier for nematogens. At least four molecular processes are resolved in the dielectric relaxation spectra in the nematic phase for each of the two tetrapodes. Three of them are assigned to the reorientation of the monomeric unit whereas the fourth is assigned to the rotation of the molecular segments in the individual arms of the monomeric unit around the long molecular axis. The dielectric relaxation strength of the low frequency process has been used to calculate the orientational order parameter. The dynamics of the resolved processes has been quantitatively analyzed using the results of the microscopic model of the rotational diffusion, given by Coffey and Kalmykov [W. T. Coffey and Yu. P. Kalmykov, Adv. Chem. Phys. 113, 487 (2000)] using the calculated order parameter. All molecular processes: the rotation around the short molecular axis (end-over-end rotation), precession around the director and the rotation around the long molecular axis (also called the spinning motion) are shown to have successfully been reproduced by the model. The anisotropy of the rotational diffusion coefficients gradually increases with a reduction in temperature, to a factor of 3 in the nematic phase relative to its isotropic phase.

Experimental demonstration, using polarized Raman and infrared spectroscopy, that both conventional and de Vries smectic-A phases may exist in smectic liquid crystals with a first-order A-C* transition.

Two models exist for the orientational distribution of the long molecular axes in smectic-A liquid crystals: the conventional unimodal distribution and the "cone-shaped" de Vries distribution. The de Vries hypothesis provides a plausible picture of how, at a molecular level, a first-order Sm-A to Sm-C* transition may occur, especially if there is little or no concomitant shrinkage of the layer spacing. This work investigates two materials with such transitions: C7 and TSiKN65. The azimuthal distribution of in-layer directors is probed using IR and polarized Raman spectroscopy, which allows us to obtain orientational order parameters. In C7, we observe a discontinuous change in the order parameter, the magnitude of which is small compared with the corresponding change in the in-layer director tilt angle Theta . Assuming that the smectic-A liquid crystal is of the de Vries type, we calculate the Theta required to reproduce the apparent order parameter app, obtained from IR, by using the true order parameter , obtained from polarized Raman scattering. The results indicate that, for C7, the tilt angle so calculated is much smaller than that in the Sm-C* angle and hence de Vries behavior may not be the appropriate explanation in this case. Conversely, we find that TSiKN65 shows a different behavior to C7, which can be explained in terms of the de Vries concept. Thus, we conclude that either type of distribution may exist in Sm-A phases which undergo a first-order transition to the Sm-C* phase. We also discuss the changes in the smectic layer spacing and the orientational order parameters across the Sm-A-Sm-C* phase transition, together with changes in birefringence with applied electric field.

Atomic force microscopy and FT-IR spectroscopy investigations of human heart valves.

Human aortic, mitral, tricuspid and pulmonary heart valves were investigated by the contact mode atomic force microscopy (AFM) in air, and using FT-IR spectroscopy in the frequency range 950-4000 cm(-1). Heart valves were collected post mortem from 65-78 years old patients who died from non-cardiac diseases. All of the examined valves showed considerable heterogeneity in the surface topography of collagen fibrils as well as in their organization on the tissue surface. The AFM images revealed areas with significantly different spatial organization of the collagen fibril bundles. We observed zones with multidirectional, stacked collagen fibrils as well as areas of thin fibrils packed regularly, densely and "in phase". The majority of the collagen fibrils reproduced the typical transverse D-banding pattern, with the band interval varying in rather wide range of 70-90 nm. Using AFM imaging, objects that correspond to some pathological states of heart valves at their early stages, i.e. some forms of mineral deposits, were observed. The FT-IR spectra allowed us to recognize main components, i.e. collagen and elastin, in di.erent layers (ventricularis, fibrosa) of the valve leaflets as well as they gave also support for the presence of mineral deposits on the valve surface. The presented results showed, that the AFM imaging and FT-IR spectroscopy can be applied as a complementary methods for structural characterization of heart valves at the molecular and supramolecular levels.