Measurements Of FL Research Articles

Broad photoluminescence and photocatalysis from functional carbonaceous material-metallized porphyrin composites for UV-Vis light harvesting

Abstract Carbon in its many form has attracted huge attraction over the years owing to its biocompatibility, processability, stability and optical properties for its utilization in UV-Vis light harvesting in pure as well as modified schemes such as composite. This study reports green precursor synthesis as well as optical, structural, luminescence and catalysis study of functional carbonaceous material (FCM) in pure and composite form. This high-order self-assembly of FCM possess extraordinary photophysical and chemical properties with its functional groups rich surface making it suitable for π-π* transitions. Further its composite formation with a high absorption coefficient (more than 20,000 cm-1 in broad visible range 400-700 nm) and non-radiative (near IR) fluorescence quenching exhibiting metallized porphyrin is shown to be suitable for photocatalysis applications. These conclusions have been established using XRD, FESEM, EDX, FTIR, UV-Vis, FL and Raman spectroscopy measurements. Broad range photoluminescence for pure FCM (300-550 nm) as well as its porphyrin-based composite (400-550 nm) and further the application of composite in the photocatalytic ability for the degradation of standard methylene blue dye for degradation percentage of 62% in 120 mins in visible light while 30% in 180 mins in dark shows the correlation for sustainable synthesis and application of FCM-porphyrin composite.

Investigation of Serum Amphiregulin Concentrations in Pregnant Women Diagnosed with Isolated Fetal Growth Restriction in the Third Trimester.

We aimed to investigate serum amphiregulin (AREG) concentrations in pregnant women with isolated fetal growth restriction (FGR) in the third trimester. This cross-sectional study was conducted with 90 pregnant women who applied to the Umraniye Training and Research Hospital Gynecology and Obstetrics Clinic between January 2022 and May 2022. The FGR group consisted of 45 pregnant women diagnosed with FGR in the third trimester, and the control group consisted of 45 healthy pregnant women matched with the FGR group in terms of age and body mass index (BMI). Demographic characteristics, ultrasound findings, and neonatal outcomes were noted. As a primary outcome, the two groups were compared for maternal serum AREG concentrations. Both groups were similar in terms of demographic characteristics (p>0.05). While fetal BPD, AC, and FL measurements in the group diagnosed with FGR were significantly lower than in the control group, umbilical artery Doppler PI and S/D were higher (p=0.000, for all). Gestational age at birth, newborn birth weight, birth height, and 1-minute Apgar score were significantly lower and the NICU admission rate was higher in the FGR group (p=0.000, p=0.000, p=0.000, p=0.027, p=0.011 respectively). Gestational age at blood sampling for AREG was similar in both groups (p=0.869). While maternal serum AREG concentration was 969.39 ng/L in the FGR group, it was 795.20 ng/L in the control group (p=0.018). AUC analysis of AREG for estimation of FGR in ROC analysis was 0.57 (p<0.247, 95% CI=0.44-0.69). The optimal threshold value for FGR estimation of maternal serum AREG concentration was determined as 874.03 ng/L with 55% sensitivity and 55% specificity. High maternal serum AREG concentrations appear to be associated with isolated FGR in the third trimester. The pathways through which AREG modulates fetal growth remain to be investigated.

Enhanced Photocatalytic Performance of Visible-Light-Driven BiVO4 Nanoparticles through W and Mo Substituting

Bismuth vanadate (BiVO4), W-doped BiVO4 (BiVO4:W), and Mo-doped BiVO4 (BiVO4:Mo) nanoparticles were synthesized at pH = 4 using a green hydrothermal method. The effects of 2 at% W or Mo doping on the microstructural and optical characteristics of as-prepared BiVO4 nanoparticles and the effect of combining particle morphology modification and impurity dopant incorporation on the visible-light-derived photocatalytic degradation of dilute Rhodamine B (RhB) solution are studied. XRD examination revealed that these obtained BiVO4-based nanoparticles had a highly crystalline and single monoclinic phase. SEM and TEM observations showed that impurity doping could modify the surface morphology, change the particle shape, and reduce the particle diameter to enlarge their specific surface area, increasing the reactive sites of the photocatalytic process. XPS and FL measurements indicated that W- and Mo-doped nanoparticles possessed higher concentrations of oxygen vacancies, which could promote the n-type semiconductor property. It was found that the BiVO4:W and BiVO4:Mo powder samples exhibited better photocatalytic activity for efficient RhB removal than that shown by pristine BiVO4 powder samples under visible light illumination. That feature can be ascribed to the larger surface area and improved concentration of photogenerated charge carriers of the former.

Osteological Correlates of Fascicle Length and Gape in Carnivora

Previously, our lab has studied the scaling and dietary correlates of masticatory muscle fiber architecture separately in felids, musteloids, canids, and ursids as well as across the carnivoran order as a whole. In some of these lineages, fascicle lengths (FLs; a correlate of gape) scale with relative diet size, while across the order and divisions thereof, correlates of bite force (muscle mass and physiological cross‐sectional area; PCSA) predominantly scale with body size. In a subsequent recent analysis of 40 taxa spanning eight families from this broader sample, we found that volumetric estimators (e.g., the commonly used “dry‐skull” method described by Thomason) can be used to closely estimate muscle mass and PCSA from osteological remains alone. In the current investigation, we are using the same sample to evaluate osteological correlates of dissection‐based FL measurements. In a preliminary analysis of 14 musteloid taxa representing mustelids, mephitids, and procyonids, chosen because musteloid FL correlated best with diet size, we measured 13 origin to insertion distances to compare to the FLs of the masticatory adductors of these taxa. Raw individual and combined osteological distances were then regressed against FL for each individual muscle as well as average adductor FL using RMA regression. Residuals of same variables relative to body mass and cranial size were also compared. The most highly correlated raw osteological measurement for each muscle resulted in r2 values of 0.92‐0.65 for the best correlate of each adductor individually and their combination. However, correlations dropped substantially (r2=0.69‐0.29 for temporalis, masseter, and all adductors combined) when body size was accounted for, and the medial pterygoid osteological FL proxies accounted for almost none of the variation in measured FL (r2=0.08 for its highest proxy). Although the temporalis is the largest mandibular adductor, the best osteological proxies for relative FL were found for the masseter muscles (r2=0.69 vs. r2=0.29 for temporalis) – perhaps because the temporalis origin is affected by the neuro‐protective and sensory functions of the cranium, while the origin to insertion region of the masseter is almost entirely influenced by masticatory function. Combining these findings with measures of jaw leverage, it is possible to reconstruct not only FL in fossil musteloids but also gape – a method that may give new insight into relative diet sizes consumed by these taxa. Expanding our methods across the other members of the order will allow for the theoretical ex vivoapproximation of gape in modern taxa for which in vivo data have not been systematically collected and also myological approaches to gape estimation in extinct taxa like Smilodon and other sabertooths.

The DRAKE mission: finding the frequency of life in the Cosmos

ABSTRACT In the search for life in the Universe, exoplanets represent numerous natural experiments in planet formation, evolution, and the emergence of life. This raises the fascinating prospect of evaluating cosmic life on a statistical basis. One key statistic is the occurrence rate of life-bearing worlds, fL, the ‘frequency of life’ term in the famous Drake Equation. Measuring fL would give profound insight into how common life is and may help us to constrain origin-of-life theories. I propose fL as the goal for the DRAKE mission (Dedicated Research for Advancing Knowledge of Exobiology): a transit spectroscopy survey of M-dwarf habitable zone terrestrial planets. I investigate how the uncertainty on the observed value of fL scales with sample size. I determine that sampling error dominates over observational error and that the uncertainty is a function of the observed fL value. I show that even small sample sizes can provide significant constraints on fL, boding well for the transit spectroscopy approach. I perform a feasibility study of the DRAKE mission using a nominal instrument design and mission plan. Due to low observing efficiencies, DRAKE may need to be incorporated into a wider-ranging deep-space or lunar observatory. A 50-planet survey could constrain fL to ≤ 0.06 (at 95 per cent confidence) if the sample fL = 0, or 0.03–0.2 if the sample fL = 0.1. This can be achieved (on average) in 10 yr using a 17-m telescope with an unrestricted field-of-regard. DRAKE is a viable approach to attempting the first experimental measurement of fL.

480: Umbilical artery Doppler discordance in fetal growth restriction

Contemporary antepartum surveillance for fetal growth restriction (FGR) consists of serial umbilical artery Doppler waveform assessments from a “free loop” (FL) of cord without regard to the specific artery being sampled. The primary objective of this study was to establish the frequency of discordant blood flow patterns between right and left umbilical arteries at the abdominal wall insertion site (AWI). Secondary aims included determining the frequency of discordance between FL and AWI patterns, and whether deterioration of Doppler waveforms occurred in a synchronous pattern. A descriptive prospective cohort study of patients diagnosed with IUGR between 23 0/7 -36 6/7 weeks gestation. Umbilical artery FL Doppler was obtained per routine clinical practice, with additional study waveforms acquired of both right and left umbilical arteries at the AWI. Doppler patterns were assigned 1 of 6 classifications. Baseline maternal demographics, obstetrical complications, gestational age at delivery, and neonatal birthweights were abstracted from medical records. Median gestational age at IUGR diagnosis was 31.4 weeks. Among the 70 participants, 50 (71.4%) had more than 1 Doppler measurement recorded, for a total of 238 examinations. At the initial study measurement, 14 patients (20%) had discordant AWI waveforms. When comparing AWI to FL measurements, discordance was found in 23 cases (33%). Progression of at least 1 AWI Doppler occurred in 23 patients (33%), and progression was discordant in 20 cases (29%; Table1). Frequent variability exists between arterial umbilical Doppler flow patterns in growth restricted fetuses, both at time of diagnosis and during subsequent measurements. The current study was descriptive, thus the clinical significance of this finding is indeterminate at present. Further investigations are needed to determine if umbilical artery Doppler discordance could conceivably represent an additional parameter for antepartum monitoring in fetal growth restriction.

Pyrazoline based chloride sensor for body fluids screening

The fluorescence detection of different electrolytes existing in body fluids represents a modern method for diagnosis of diseases. This work reports the use of a pyrazoline derivative as a new fluorescence chloride sensor based on a dynamic quenching mechanism. Moreover, we show that 1,3-diphenyl-5-{4-[(4-vinylbenzyl)oxy]phenyl}-4,5-dihydropyrazole is capable to detect multiple halides and behave differently depending on the nature of either the halide or the metal counterion. The optical properties of this pyrazoline in the presence of halides of alkaline and several transitional metals have been determined by UV–Vis and FL measurements in solution. Stern-Volmer equation used for fluorescence data analysis revealed interesting particularities depending on the selected quencher. We discovered that the aforementioned pyrazoline is highly sensitive to potassium chloride or iodide, but, is inert to potassium bromide. Quantum mechanical calculations were employed to generate the molecular models of the pyrazoline in ground and excited state, with the view to obtain the HOMO-LUMO energy gap and mapped electrostatic isopotential. Thus, it was possible to explain the sensitivity for chloride and establish the fluorescence quenching mechanism. This pyrazoline derivative may be used to expand the class of fluorescent materials with improved chloride sensitivity and develop multi analysis systems.

EP05.12: Fetal biometry and growth curves for Indian women by fetal biometry: restructured for regression equation curves

To restructure fetal biometry and growth curve developed in 2006-07. Data were published in 2009. A longitudinal prospective study was carried out. Thirty patients were included and ultrasound scans were performed on Indian pregnant women to measure fetal growth parameters of biparietal diameter, head circumference, abdominal circumference and femur length for every weekly interval from 14 to 40 weeks. Twenty-five hundred women had ultrasonic measurements of fetal BPD,HC, AC and FL between 12 to 42 weeks of pregnancy were also included in study for confirming the growth parameters and plotting of growth curves. Statistical analysis has been performed using MS excel 2010. Data analysed as recommended by Altman, Chitty and Royton. For each measurement, polynomial regression models were fitted separately to estimate the mean and standard deviation (SD) as functions of gestational age. The SD was modelled via the absolute residuals from the regression to estimate the mean. Assuming that at each gestation, the measurements have a normal (Gaussian) distribution, with mean and standard deviation, and that both vary smoothly with gestational age, Centile curve is calculated using the formula, Centile = mean + k * SD Where k is the corresponding centile of standard Gaussian distribution. Determination of 1st, 3rd, 5th, 10th, 50th, 90th, 95th and 99th centile curves require k = -2.326, -1.96, -1.645, -1.282, +1.282, +1.645, +1.960 and +2.326 respectively. Regression equations were derived with polynomial regressions where R-value is closure to 1. We have calculated new regression equation for the fetal growth for the Indian population and since it was developed, by prospective study on 25 patients on weekly scan, accuracy will be better. Supporting information can be found in the online version of this abstract Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Biparietal diameter measurements using the outer-to-outer versus outer-to-inner measurement: A question of pedantry?

To compare two methods of measuring fetal biparietal diameter (BPD) - outer-to-inner (BPDoi) vs. outer-to-outer (BPDoo) calliper placement - and to compare the differences in EFW calculated using the Hadlock 4 formula and other common EFW formulae. A total of 543 fetuses underwent a single ultrasound prospectively performed by 40 sonographers between 14 and 40 weeks of gestation, taking into account the intra- and inter-observer variability. The measurements for each fetus consisted of BPDoi and BPDoo, and EFW is calculated from HC, AC and FL measurements. The difference between BPDoo and BPDoi was estimated, and this difference was compared with gestational age using linear regression. Translational equations that allow interconversion of the two parameters were derived. EFW calculated from four different formulae using various combinations of biometric measurements was compared. The difference between BPDoi and BPDoo increases with gestational age, although this difference was small. For BPDoo, the regression equation is BPDoo = 0.555934 + 1.027318 × BPDoi. Similarly, for BPDoi, the regression equation is BPDoi = -0.403458 + 0.9714153 × BPDoo. There is a minimal difference in the EFW calculated from the four formulae, except for gestations prior to 27-28 weeks. EFW derived from INTERGROWTH-21st formulae plot is higher than that from Hadlock 3 or Hadlock 4 before 27-28 weeks. Although the absolute difference between BPDoo and BPDoi increased across gestational age, this difference was small. The method of BPD measurement should follow that as prescribed in the EFW equation used in the local context. Estimation of fetal weight using Hadlock 3, Hadlock 4 and INTERGROWTH-21st is similar, with slight differences at gestations less than 27-28 weeks.

A general analysis of Wtb anomalous couplings**Supported by National Science Foundation of China (11275009, 11675002, 11635001), National Science Foundation (PHY-1315983, PHY-1316033) and DOE (DE- SC0011095)

We investigate new physics effects on the Wtb effective couplings in a model-independent framework. The new physics effects can be parametrized by four independent couplings, , , and . We further introduce a set of parameters x0, xm, xp and x5 which exhibit a linear relation to the single top production cross sections. Using recent data for the t-channel single top production cross section σt, tW associated production cross section σtW, s-channel single top production cross section σs, and W-helicity fractions F0, FL and FR collected at the 8 TeV LHC and Tevatron, we perform a global fit to impose constraints on the top quark effective couplings. Our global fitting results show that the top quark effective couplings are strongly correlated. We show that (i) improving the measurements of σt and σtW is important in constraining the correlation of (,) and (,); (ii) and are anti-correlated, and are sensitive to all the four experiments; (iii) and are also anti-correlated, and are sensitive to the F0 and FL measurements; (iv) the correlation between and is sensitive to the precision of the σt, σtW and F0 measurements. The effective Wtb couplings are studied in three kinds of new physics models: the G(221) = SU(2)1 ⊗ SU(2)2 ⊗ U(1)X models, the vector-like quark models and the Littlest Higgs model with and without T-parity. We show that the Wtb couplings in the left-right model and the un-unified model are sensitive to the ratio of gauge couplings when the new heavy gauge boson’s mass (MW′) is less than several hundred GeV, but the constraint is loose if MW′ > 1 TeV. Furthermore, the Wtb couplings in vector-like quark models and the Littlest Higgs models are sensitive to the mixing angles of new heavy particles and SM particles.

Photochemical synthesis and enhanced photocatalytic activity of MnOx/BiPO4 heterojunction

Monoclinic BiPO4 with rod-like shape was prepared via a CTAB-assisted hydrothermal route. MnOx nanoparticles were loaded on the surfaces of BiPO4 rods by a photo-deposition process to form MnOx/BiPO4 heterojunctions. The as-prepared samples were characterized by XRD, SEM, TEM, XPS, FL, and UV-Vis diffuse reflectance measurements. The results showed that MnOx nanoparticles were strongly anchored to the surfaces of BiPO4 rods when the mole ratio of Mn to Bi was controlled at a low level, forming MnOx/BiPO4 heterojunctions with effective and sound interfaces. The MnOx/BiPO4 heterojunctions exhibited higher photoactivity than pristine BiPO4 for photodegradation of methyl blue under UV irradiation, which could be attributed to the efficient charge transfer at the heterojunction interfaces. The higher light absorption ability of MnOx/BiPO4 in the range of 300–420 nm compared with pristine BiPO4 was also responsible for the enhanced photocatalytic activities of MnOx/BiPO4 heterojunctions.

Validity of common ultrasound methods of fetal weight estimation in late pregnancy among women in Kwale, Niger Delta region, Nigeria.

Accuracy of some ultrasound equations used in our locality for fetal weight estimation is doubtful. To assess the accuracy of common ultrasound equations used for fetal weight estimation. A longitudinal study was conducted on selected Nigerian obstetric population at Central Hospital, Kwale between March, 2009 and January, 2011. Sonography was performed on 412 women with advanced singleton cyesis and measurements of BPD, HC, AC, and FL were obtained and figured into 12 common ultrasound equations for the estimation of fetal weight. The actual birth weight at delivery was recorded. The highest intraclass correlation coefficient was generated by the Hadlock 5 and Hsieh 2 equations. The least mean absolute percent error was obtained with Hsieh 2 equation, followed by Woo 3, and Hadlock 5. These equations also had the least percentage error and the least range of limits of agreement in the same order with no significant difference between their mean fetal weight estimates and that of the actual birth weight (p > 0.05). All twelve equations had strong positive correlation with the actual birth weight with Nzeh 2 equation the least. Hsieh 2 equation has the best accuracy in fetal weight estimation studied.

Fetal Ci̇nsi̇yeti̇n Ultrasonografi̇k Fetal Bi̇yometri̇k Parametreler Üzeri̇ne Etkisi (The Impact of the Fetal Gender on Ultrasonographic Fetal Biometric Parameters)

Objective: One of the most important parameters to assess the fetal well-being status is fetal weight. It has been known that fetal weight is effected by many characteristics such as maternal weight, stature, smoking habit, parity and ethnicity in addition to fetal gender. In the present study our aim was to assess whether fetal gender had any impact on ultrasonographic BPD, HC, AC, FL and EFW measurements in low-risk singleton pregnancies. Material and Methods: Fetal ultrasonographic measurements were made on the 15-22, 23-26, 27-30, 31-34, 35-38 and 39-40th weeks of gestation seperately and EFWs were calculated. It was evaluated whether any significant difference existed between the two genders on these gestational weeks. Statistical analyses were made using chi-square, student’s t and Mann-Whitney U tests where appropriate.Results: In terms of actual birth weight, male newborns were significantly heavier. Of the sonographic measurements, only HC on 39-40th gestational weeks were significantly greater in male fetuses. In male fetuses there was a good-very good correlation between actual birth weight and AC and EFW. Conclusions: In our study, we determined that fetal gender does not have any impact on antenatal sonographic measurements except for HC was measured greater in male fetuses on the 39-40th gestational weeks. Moreover, it was observed that fetal sonographic parameters were significantly correlated with the actual birth weights and that there was a good correlation between EFW and actual birth weight irrespective of the fetal gender.

Length–Length and Width–Length Conversion of Longnose Skate and Big Skate Off the Pacific Coast: Implications for the Choice of Alternative Measurement Units in Fisheries Stock Assessment

AbstractMost traditional fisheries models have size or stage–age relationships as their foundation. Two long‐established metrics used are FL and TL. Body length measurements are linked to age, maturity, and fecundity. Obtaining FL or TL measurements are not always convenient, especially for larger fish (&gt;100 cm TL). Two skate species, Longnose Skate Raja rhina and Big Skate R. binoculata, were collected from commercial fishery landings along the coast of Washington State and length–length or width–length conversions were investigated for four metrics of size: TL, tail only length (TOL), interspiracular width (ISW), and interorbital width (IOW). Relationships between TL and alternative measures were examined using model II regression analyses and confirmed a strong linear relationship in all cases (R 2 &gt; 0.94). It is likely that both TL and TOL measures have errors due to worn‐off tail portions; conversely, the ISW is nonlaborious and convenient to obtain. The ISW metric has a smaller coefficient of variation compared with IOW if we assume that both metrics have the same distribution of measurement errors. We recommend ISW as the preferred alternative metric in the assessment of large skate. The ISW will probably yield measurements that are equivalent, or potentially superior, to traditional metrics because the measurement is taken from body parts devoid of worn‐off portions.Received December 30, 2011; accepted June 13, 2013

New Gestational Age Parameter - Transverse Diameter of Heart - TDH

Introduction: Fetal growth assessment, for induction and timing of repeat caesarean, relies on accurate gestational age. Various ultrasonography fetal biometry has been used to assess gestational age in practice. This information is invaluable because most obstetrical management decisions are strongly influenced by consideration of fetal development, which closely correlates with fetal age. Aim: To evaluate the accuracy of fetal Transverse Diameter of Heart (TDH) measured by real time ultrasound to predict the gestational age during second&Third diameter and to correlate with FL. BPD, AC, HC to assess variation. Materials & Methods: Prospective Study was carried out at Saveetha Medical College. Total 150 cases attending antenatal clinic in first, second&third trimesters were considered. Routine measurements of FL, BPD, HC, AC along with TDH taken. TDH is taken in mm at closed AV valve junction, outer to outer points in four chamber view of heart. Results: Out of 150 cases 64 were in second trimester, 86 in third trimester. 102 patients had confirmed first trimester gestational age TDH in second&third trimester is more closed to actual gestational age than average gestational calculated by other parameters. The TDH was calculated and found that the variance in the second half (from 28 weeks onwards) was stated to be very less as shown in the tabulated value as variance of 0.01376 as against first half of 0.0393. The population confidence interval was 0.95%. From Predicted value of TDH&confidence interval, we suggest that when compared to other parameters like BPD Bipariteal diameter, HC head circumference FL femur length. AC abdominal circumference - TDH Transverse diameter of heart dimensions are equivalent to actual gestational age from 28 week on wards. Conclusion: TDH can be a useful parameter when LMP is not known. It can be used as additional parameter when ever needed.

The new [formula omitted] measurement from HERA and the dipole model

From the new measurement of FL at HERA we derive fixed-Q2 averages 〈FL/F2〉. We compare these with bounds which are rigorous in the framework of the standard dipole picture. The bounds are sharpened by including information on the charm structure function F2(c). Within the experimental errors the bounds are respected by the data. But for 3.5 GeV2⩽Q2⩽20 GeV2 the central values of the data are close to and in some cases even above the bounds. Data on FL/F2 significantly exceeding the bounds would rule out the standard dipole picture at these kinematic points. We discuss, furthermore, how data respecting the bounds but coming close to them can give information on questions like colour transparency, saturation and the dependencies of the dipole-proton cross section on the energy and the dipole size.

Multi-addressable molecular switches based on photochromic diarylethenes bearing a rhodamine unit

Two novel diarylethene derivatives bearing a rhodamine unit have been successfully synthesized. Their unique multi-addressable switching characteristics as induced by chemical and optical dual inputs stimulation were observed using UV and FL measurements. The two diarylethenes showed excellent photochormism with alternating UV/vis light irradiation. Addition of trifluoroacetic acid (TFA) protonated the diarylethenes, which resulted in good photochromism and notable fluorescence change via the FRET mechanism. Subsequent addition of triethanolamine base would neutralize and return both their protonated open-ring and closed-ring isomers to their original forms. It was found that the diarylethene bearing a rhodamine unit linked by a benzhydrazide bridge group was more sensitive, efficient and reacted faster to protonation by TFA when compared to the benzamide bridged derivative. Furthermore, the benzhydrazide bridged diarylethene derivative was found to be selective towards Cr(III), Al(III), or Ca(II) with significant color and fluorescence changes.

OC20.02: Assessment of sonographers' variability in ultrasound measurements of BPD, HC, AC and FL

OC20.02: Assessment of sonographers' variability in ultrasound measurements of BPD, HC, AC and FL

A proton and optic dual-control molecular switch based on photochromic diarylethene bearing a rhodamine unit

A novel fluorescent switch based on rhodamine B and photochromic diarylethene, 1-[2-methyl-5-(4-methoxylphenyl)-3-thienyl]-2-[2-methyl-5-(4-rhodamine B hydrazine-Schiff base-phenyl)-3-thienyl]perfluorocyclopentene (1), has been successfully synthesized through the condensation of rhodamine B hydrazine and 1-[2-methyl-5-(4-methoxylphenyl)-3-thienyl]-2-[2-methyl-5-(4-formylphenyl)-3-thienyl]perfluorocyclopentene. UV and FL measurements reveal that the compound exhibits good photochromic properties responsive to proton and optic dual inputs. Upon irradiation with 297 nm light, the colorless solution of compound 1 turns blue, while the blue solution becomes colorless after irradiated with visible light (λ>450 nm). Furthermore, upon an addition of H+, the fluorescence resonance energy transfers from the rhodamine unit (FRET donor) to the closed-ring diarylethene unit (FRET acceptor), although no energy transfer occurs when the diarylethene is in the open-ring form. The emission intensity of the rhodamine can be modulated with proton and UV/vis light and molecular-level signal communication has been constructed, indicating high potentials of the compound in molecular switches or naked eye recognition systems.

Preparation and Characterization of PBMA/SiO2-TiO2Hybrid Fibres

Silica-titania (SiO2-TiO2) blend sols were prepared via a sol-gel method from tetraethoxylsilane and tetrabutyl titanate. Poly(butyl methacrylate) (PBMA)/SiO2-TiO2hybrid sols were synthesized through in-situ polymerization of butyl methacrylate (BMA) in the blend sol. After ageing treatment, PBMA/SiO2-TiO2hybrid fibres were prepared by drawing from the hybrid sol. The mechanism of the hybrid reaction was studied carefully. The hybrid fibres were characterized by Fourier transform infrared (FT-IR) spectrometry, scanning electron microscopy (SEM), High-resolution transmission electron microscopy (HRTEM), Fluorescence Spectrophotometry (FL), Ultraviolet Visible Spectrometry (UV-Vis) and Thermogravimetric Analysis (TGA). FT-TR results suggested that PBMA was linked to SiO2-TiO2network through chemical bonds. SEM measurements indicated that the diameter of the fibres was about 50 μ m, and the whole system was homogeneous. HRTEM images showed that the dimensions of the organic phase were about 50 nm, and the distributions of the organic phase were not very uniform. FL and UV-Vis measurements confirm the fluorescence of the hybrid fibres with improved shielding to UV TGA measurements suggest that the hybrid fibres show better resistance to heat than pure PBMA.