bluuebunny/crossref_metadata_2025 huggingface dataset:
Terahertz time-domain spectroscopy of congruent LiNbO3 and LiTaO3 crystals
Authors: Igawa Hikaru , Mori Tatsuya , Kojima Seiji
Published: March 2014

The complex dielectric constants of congruent LiNbO3 and LiTaO3 single crystals in a THz frequency region have been determined directly by using broadband terahertz time-domain spectroscopy (THz-TDS) with reflection configuration. We have successfully extracted the accurate complex dielectric constants by using corrected phase information derived from the transmission measurement results. The lowest E(TO1) phonon modes of both crystals have been observed clearly. On the other hand, additional bands at approximately 2.5 THz below the lowest A
1(TO1) mode frequency have been observed. These bands have also been reported by Raman and hyper-Raman spectroscopy and attributed to intrinsic defects in congruent crystals. According to the experimental results that these additional bands were observed at almost the same frequency on Raman, hyper-Raman, and THz-TDS, these bands are suggested to be assigned as a first-order scattering process.
Light Fluctuations as a New Spectroscopic Tool
Authors: Wolf E.
Published: March 2014

In the first part of this lecture, basic concepts relating to the theory of light fluctuations are presented and some features which distinguish the fluctuation properties of thermal and laser light are mentioned. A survey is then made of various new techniques proposed by many authors, for obtaining information about spectra from fluctuation and correlation measurements. In particular, intensity correlation interferometry, photon coincidence methods and pulse counting techniques are reviewed.
Current researches relating to the determination of the phase of the second order complex degree of coherence–the knowledge of which is of importance for an unambiguous determination of asymmetric spectral profiles from some of these experiments–is also discussed. Theoretical methods for obtaining this phase information utilize the analytic properties of coherence functions. Proposed experimental methods make use of the technique of the coherent background and of three point correlation measurements.
Finally the notion of spectral correlation function is introduced and it is shown how it is related to higher order coherence functions. The possibility of obtaining some information about spectral correlation from multiple photon coincidence experiments is also mentioned.
Automatic Recording Instrument for Measuring Optical Transfer Functions
Authors: Baker L. R.
Published: March 2014

An instrument is described which is capable of recording automatically both the amplitude and the phase of the O. T. F., as would be required by a test laboratory. A simplified version permits a continuous display on a C. R. T. and this is suitable for rapid workshop assessment of lens performance. The basic system consists of an object generator, an image analyser, and an electronic processing unit. By imaging part of a rotating radial grating on to a slit and then varying the orientation of the lines with respect to the slit it is possible to generate a periodic test pattern of constant contrast but in which the spatial frequency varies over a range of 100 to 1 and includes zero c/mm. The image of this object produced by the lens under test drifts at a constant rate over an analysing slit and photo-multiplier. A single low pass filter selects the fundamental of the photo-multiplier signal and this is proportional to the amplitude of O. T. F. of the lens under test. A reference optical system and photo-multiplier is used to measure phase and to provide a facility for null measurement by phase coherent detection.
Attempts to Treat Nonlinear Imaging Devices
Authors: Ingelstam Erik
Published: March 2014

Imaging devices, other than pure optics in the case of incoherence, often work in a nonlinear way, consequently linear transfer theory fails to apply. Nonlinearities may be of the zero-spread or the finite-spread type. Conditions are examined to determine if describing functions for certain classes of objects may be used as generalized transfer functions, retaining some of their favourable properties. Adjacency effects can be linear or nonlinear. Electro-optics, radiology, photography, xerography, and the visual system are briefly treated in view of these concepts.
Some Properties of Random Charts
Authors: Kinoshita Kojiro
Published: March 2014

Three kinds of one-dimensional random charts, corresponding to stochastic “normal,” “uniform” and “beta” distribution function, were constructed and their properties, as to the convergence of the run, the mean value and the standard deviation, were investigated.
A simple auto-correlogram method was proposed to determine roughly those properties of two-dimensional random charts, which were obtained by arranging one-dimensional charts in two dimensions.
Geometrical Optical Approximation of Optical Transfer Function
Authors: Miyamoto Kenro
Published: March 2014

The geometrical optical expression of optical transfer function
R

g
(s,t)=a
-1\int\int
A
exp
[-2πi(s∂/∂u+t∂/∂v)φ(u,v)]d
u
d
v

is a fairly good approximation of wave optical one, when the wave aberration function φ(u, v) is larger than, say, two wavelength. However the expression of R
g(s,t) is no longer utilized in the case of small aberration. The alternative approximate expression,
R

a
(s,t)=a
-1\int\int
Aλs λt
exp
[-2πi(s∂/∂u+t∂/∂v)φ(u,v)]d
u
d
v,

which is still simple to calculate, is studied and it is confirmed that this approximation is good in the region of |λs|, |λt|<0.5 even in the case of small aberration.
Effect of Coherence on the Slit Function
Authors: Sakai Hajime
Published: March 2014

Influence of the coherence in the entrance slit illumination on the slit function of the spectrometer is investigated in the Fourier transform domain, where reconstruction of the true spectrum from the distorted spectrum may be made more directly. The slit function Fourier transform obtained in practice is found to be quite different from the one for the coherent or incoherent case when the slit width is set approximately equal to the width of the diffraction pattern due to the limiting aperture in the spectrometer optics (u≈1.0); this is usually done in order to utilize the full resolving power of the spectrometer. However, the spatial frequency band-pass remains the same as for the coherent or incoherent case.
Mechanical Stresses in Vacuum Deposited Films of Ag, MgF2 and ZnS
Authors: Kinosita Koreo , Nakamizo Kozo , Maki Kunisuke , Onuki Kota , Takeuchi Kyoko
Published: March 2014

The film material is deposited at 10-5 Torr onto a thin strip of mica clamped at one end, and the stress within the film is determined by observation of the bending of the strip. The total stress S and the mean stress per unit cross section of the film σ are given as functions of the film thickness d up to a few thousands of ångströms taking the deposition rate as a parameter. The stress in MgF2 films is tensile, σ assuming a maximum at a thickness (≈1,000 Å) which depends on the deposition rate. ZnS films deposited slowly (1–3 Å/s) exhibit tensile stress. If deposited at faster rates (8–17 Å/s) they show compressive stress in the range d<1,200 Å; above this thickness the stress becomes tensile. Silver films exhibit tensile stress, and σ assumes a maximum in the thickness range 100 to 200 Å where the crystallites coalesce to form a coherent film.
Spectral Reflectance of Lippmann Plate
Authors: Iwata M. , Makabe R. , Katsube S.
Published: March 2014

The spectral reflectance of an inhomogeneous film whose refractive index varies quasi-sinusoidally in the direction normal to the surface are calculated for various film thicknesses and for various refractive index distributions. The emulsion film of a Lippmann plate is presumed to have such a structure. The results are compared with the experimental results with Lippmann plates.
An Application of Double Chopping System, to Far Infrared Spectrophotometer
Authors: Minami S. , Yoshinaga H. , Matsunaga K.
Published: March 2014

The double chopping system of radiation using two well-separated carrier frequencies is applied to the optical null double-beam far infrared Spectrophotometer in order to eliminate an error due to the sample radiation. The double chopping attachment which is composed of an additional chopper and simple electronics makes the optical null instrument entirely insensitive to the sample temperature.
Measurement of Spectral Transmittance and Reflectance with a Far Infrared Michelson Interferometer
Authors: Bell Ely E.
Published: March 2014

The use of a Michelson interferometer to obtain the spectral dependence of the optical properties of samples placed in one beam of the interferometer is discussed and illustrated by examples. The spectral dependence of the index of refraction of a sample of crystal quartz is obtained from the full sine and cosine Fourier transformation of the interferogram obtained with the sample in transmission. The amplitude and phase of the reflection from a KBr sample is obtained in a similar manner. A short description of the uncollimated Michelson interferometer with metal mesh beam splitters is given. Results have been obtained in the spectral region from a few reciprocal centimeters to 250 reciprocal centimeters.
The Correction of Optical Systems
Authors: Herzberger M.
Published: March 2014

The author has on previous occasions analyzed the optical image as a superposition of five images corresponding to image formation of first order (astigmatism), second order (asymmetry), third order (Gullstrand errors), fourth order (secondary coma), and fifth order (secondary spherical aberration).
To a set of concentric circles in the exit pupil corresponds a set of concentric similar figures in the image, the dimensions of which vary with the first, third, and fifth powers of the aperture, and to a set of eccentric similar figures, the dimensions of which vary with the second and fourth powers of the aperture. The vector sum of all five figures gives the spot diagram and with it the light distribution in the image.
Since the elementary images are of simple forms, the change of system data can be easily used to balance the image.
Recently the use of aspheric surfaces has become rather common, so we shall also demonstrate how to correct an optical system by the proper selection of the coefficients of an aspheric surface.
Polarizers for the Extreme Ultraviolet
Authors: Hunter W. R.
Published: March 2014

The polarizing properties of materials in the extreme ultraviolet are being studied for the purpose of developing both reflecting and transmitting polarizers. Calculations of the ratios R
8/R

p
=ρ and T

P
/T
8=1/ρ have been made for some of those materials whose optical constants have been measured and an attempt was made to verify the calculated ratios experimentally where possible. The calculations indicate the possibility of making transmitting polarizers, using multilayer unbacked metal films, for wavelengths less than the critical wavelength of the metal. The calculated value of 1/ρ for Au/Al/Au at 640 Å and i=42° was found to be 15, but T

p
, for this multilayer film, is only a few percent. Reflecting polarizers, which are much less convenient to use, show more complete polarization. For example, for Au/Al/Glass at 640 Å, ρ=35 at i=62°, and R
8=30%.
Determination of Optical Constants of Glasses in the Vacuum Ultraviolet Region
Authors: Sasaki T. , Fukutani H. , Ishiguro K. , Izumitani T.
Published: March 2014

Optical constants of several optical glasses and fused quartz between 7 and 23 eV are reported. After a brief description of the method of determining optical constants from the reflectances measured at two or more angles of incidence and the graphical analysis of data, the results are given in terms of n, k, n
2-k
2, and n
kν, with some remarks on their accuracies. An absorption band was observed at about 14 eV in the fused quartz and two of the glasses examined and has been tentatively assigned to the characteristic electronic transition of SiO2.
An Absolute Method of Determining Transmission and Reflection Coefficients
Authors: Fray S. J. , Goodwin A. R. , Johnson F. A. , Quarrington J. E.
Published: March 2014

An absolute method of making simultaneous measurements of the transmission and reflection coefficients of semiconductors and insulators to a precision of better than 1% has been developed for use in the visible and infra-red regions of the spectrum. The reduction of these measurements to the optical constants by a technique taking full account of the finite spectral bandwidth of the light is also described.
A Series of Lenses Designed for Optimum Performance
Authors: Hopkins R. E.
Published: March 2014

Six lenses have been designed with the aid of an automatic correcting program. The lenses were designed to the following specifications: focal length 24 inches, f-number 6.0, full field format 9×9 inches square. Two lenses were triplets, two were four element lenses, one was a triplet with four aspheric surfaces and one used five elements. The four element lenses appear to have the best performance.
Optical Faraday Effect of II–VI Compound Crystals
Authors: Koda Takao , Ebina Atsuko , Shionoya Shigeo
Published: March 2014

Faraday effect of various IIb–VIb compound crystals, including ZnS, CdS, ZnO, ZnSe, and ZnTe, was measured at frequencies just below the fundamental absorption edge down to lower frequencies. Observed Faraday rotations were interpreted in terms of the intrinsic interband electronic transitions, and attempts were made to fit the observed spectral dependences of the rotation with theoretical expressions for the interband Faraday effect. The preliminary results show that the dispersive behaviors of the rotation observed in the crystals quoted above at room and low temperatures can be described fairly well by the theoretical expression given by Boswarva et al. for the simple direct interband transition. The agreement is especially satisfactory in the case of ZnS, yielding the values of 3.752 and 3.871 eV as the direct band gap energies at 286 and 107°K, respectively. It is supposed that the similarity found in the spectral behaviors of the Faraday rotations of these II–VI compounds indicates that the fundamental absorptions in these crystals are associated with the allowed direct interband transitions.
Stimulated Emission of New Infra-red Transitions in Rare Gases
Authors: Cagnard R. , Agobian R. Der , Otto J. L. , Echard R. , Pauthier M.
Published: March 2014

The study of rare gases by means of a very long wide-band optical maser (1 to 3.5 µ) has made it possible to observe most of the known transitions in this range and to identify 15 new stimulated transitions.
Among the important results of this study, should be mentioned oscillation of the transition 33D–43P of helium and the obtention of oscillations for six transitions in the group 2s–3p of neon.
The discovery of another phenomenon, namely the existence of several “cascades” of stimulated transitions, both in the He-Ne mixture and in pure neon, made it possible to determine the excitation mechanisms in the discharges. These “cascades” also present the advantage of increasing the gain, and consequently the usable power of stimulated transitions of near infra-red.
Automatic Lens Design
Authors: Suzuki T. , Ichioka Y. , Yonezawa S. , Koyama M.
Published: March 2014

A new method for automatic lens design on electronic computer is described. An unique target point which has been used on automatic lens design procedures to define a set of target values in multi-dimensional aberration space is replaced with a domain with non-zero volume arround the target point. The volume itself defines the amount of tolerances allowed to respective aberrations. Iterative cycles are used to find the solution. In each cycle the aberrations are corrected one by one without violating the aberrations which have been corrected in the previous cycles. The iteration are continued until we can find the final solution, a set of lens parameters, which satisfies all of aberrations taken into consideration. The boundary conditions can be treated just in the same manner as aberrations. A triplet lens was presented to the program as the test of the procedure and satisfactory results were obtained.
Exploring Organizational Culture Dimensions in a Lake-Based Eco-Tourism Resort
Authors: Yusof Nor’Aini , Che Jamil Mohd Fitri
Published: March 2014

Ecotourism has been identified as one of the main attractions in the promotion of tourism in Malaysia. Despite having a number of breath-taking lakes, most of the well known ecotourism resorts are located in coastal-based areas. Less attention is given to the lake-based ecotourism resorts, causing concern about the neglect of management issues which have led to a low occupancy rate. Meanwhile, scholars believe that organizational culture is an important factor in effective management. However, there is a lack of studies on the management of resorts, especially concerning organizational culture. The aim of this paper is to explore the organizational culture of ecotourism resorts in an ecotourism area; Tasik Kenyir. Questionnaires were distributed to resort employees who have agreed to participate in the survey, yielding a 77% response rate. The data was analysed using factor analysis. Four factors have emerged as constructs of organizational values and another five factors emerged for organizational practice. The results provide an understanding of the organizational culture that is available in resorts in the ecotourism industry.
Personalised Travel Services: an Exploratory Study in Singapore Context
Authors: Singh Bhati Abhishek , Tack Hoong Cheong , Lian Fong Jaclyn Chang , Kaur Kanwaljit
Published: March 2014

The aims of the study were to explore the demand for personalised travel services within the affluent customer segment of the outbound travelers in Singapore. The study uncovers the desired service attributes of same consumer segment. The paper begins with a general and broad overview of the travel and tourism industry worldwide and in the Asia Pacific region specifically in Singapore. The international tourism and hospitality sector has grown rapidly over the last ten years and according to the United Nations World Tourism Organisation (UNWTO), international tourist arrivals in 2012 grew to 980 million. Similarly, there has been an increase in outbound travels in Singapore. This growth has been fuelled by the economic growth that Singapore has experienced over the years. The study surveys the current literature to provide data to show the growth of outbound travel from Singapore and the increasing number of affluent Singapore travelers. The study considers an email questionnaire survey to gauge the travel patterns and desires of the affluent traveler market in Singapore. The exploratory findings identify a market for personalized travel services in Singapore and consider an inventory of service attributes desired by the affluent customer segment in Singapore. More specifically, the findings indicate that almost 65% of respondents preferred personal travel services (PTS) with 70% who currently book tours through travel agents indicating their preference for PTS. What was particularly interesting was that over 60% of those who currently engage in self-booking found the idea of PTS appealing. The key draws of PTS are convenience, personalization of itinerary and tour package, experience of consultants and trust. Personalised travel services are targeted to the high income market and the potential demand for PTS among travelers who undertake two or more trips a year was about 72%. Travelers today are looking for more value-added services and interesting tour packages rather than the run of the mill mass tours that many travel agents still provide. Growing affluence and the desire for unique and unusual tours is creating a niche market for travel agencies to exploit. The current and common business model of providing mass tours where customers are herded on a standard itinerary does not sit well with the well-heeled and sophisticated traveler of today. Today’s affluent travelers want to be treated not as mere customers but rather as valuable clients, partnering with the tour agency to create unparalleled and enriching tour experiences.
Inhibition of type III radio emissions due to the interaction between two electron beams: Observations and simulations
Authors: Briand C. , Henri P. , Hoang S.
Published: March 2014

We report the peculiar interaction of two type III bursts observed in the solar wind. As electron beams propagating on the same magnetic field lines cross, a spectacular depletion of the type III radio emission is observed. We combine observations from the WAVES experiment on board the STEREO mission together with kinetic plasma simulations to study the extinction of type III radio emission resulting from the interaction between two electron beams. The remote observations enable to follow the electron beams in the interplanetary medium and show that the level of radiated radio waves is recovered after the beam crossing. The in situ observations of beam‐driven Langmuir waves give evidence for Langmuir decay. The density fluctuations are extracted from in situ observations. The velocity of the beams is independently evaluated from in situ observations of decaying Langmuir waves and remote radio observations. The kinetic simulations show that the level of beam‐driven Langmuir waves is reduced as the two beams cross. We show that the slow beam induced a strong reduction of the quasilinear relaxation of the fast beam, limiting the amplitude of the generated Langmuir waves. Moreover, in the case of two electron beams, the lack of Langmuir wave coherence reduces the efficiency of the Langmuir parametric decay. We thus conclude that the observed depletion of the type III radio emission is independent of the radio emission mechanism, as long as it depends on the Langmuir amplitude and coherence.
Seasonal evapotranspiration patterns in mangrove forests
Authors: Barr Jordan G. , DeLonge Marcia S. , Fuentes Jose D.
Published: March 2014

Diurnal and seasonal controls on water vapor fluxes were investigated in a subtropical mangrove forest in Everglades National Park, Florida. Energy partitioning between sensible and latent heat fluxes was highly variable during the 2004–2005 study period. During the dry season, the mangrove forest behaved akin to a semiarid ecosystem as most of the available energy was partitioned into sensible heat, which gave Bowen ratio values exceeding 1.0 and minimum latent heat fluxes of 5 MJ d−1. In contrast, during the wet season the mangrove forest acted as a well‐watered, broadleaved deciduous forest, with Bowen ratio values of 0.25 and latent heat fluxes reaching 18 MJ d−1. During the dry season, high salinity levels (> 30 parts per thousand, ppt) caused evapotranspiration to decline and correspondingly resulted in reduced canopy conductance. From multiple linear regression, daily average canopy conductance to water vapor declined with increasing salinity, vapor pressure deficit, and daily sums of solar irradiance but increased with air temperature and friction velocity. Using these relationships, appropriately modified Penman‐Monteith and Priestley‐Taylor models reliably reproduced seasonal trends in daily evapotranspiration. Such numerical models, using site‐specific parameters, are crucial for constructing seasonal water budgets, constraining hydrological models, and driving regional climate models over mangrove forests.
Reversible functional connectivity disturbances during transient global amnesia
Authors: Peer Michael , Nitzan Mor , Goldberg Ilan , Katz Judith , Gomori J. Moshe , Ben‐Hur Tamir , Arzy Shahar
Published: March 2014

Objective

Transient global amnesia (TGA), an abrupt occurrence of severe anterograde episodic amnesia accompanied by repetitive questioning, has been known for more than 50 years. Despite extensive research, there is no clear evidence for the underlying pathophysiological basis of TGA. Moreover, there is no neuroimaging method to evaluate TGA in real time.

Methods

Here we used resting‐state functional magnetic resonance imaging recorded in 12 patients during the acute phase of TGA together with connectivity and cluster analyses to detect changes in the episodic memory network in TGA.

Results

Our results show a significant reduction in functional connectivity of the episodic memory network during TGA, which is more pronounced in the hyperacute phase than in the postacute phase. This disturbance is bilateral, and reversible after recovery. Although the hippocampus and its connections are significantly impaired, other parts of the episodic memory network are also impaired. Similar results were obtained for the analysis of the episodic memory network whether it was defined in a data‐driven or literature‐based manner.

Interpretation

These results suggest that TGA is related to a functional disturbance in the episodic memory network, and supply a neuroimaging correlate of TGA during the acute phase. Ann Neurol 2014;75:634–643
Storage of Electrical Information in Metal–Organic‐Framework Memristors
Authors: Yoon Seok Min , Warren Scott C. , Grzybowski Bartosz A.
Published: March 2014

Single crystals of a cyclodextrin‐based metal–organic framework (MOF) infused with an ionic electrolyte and flanked by silver electrodes act as memristors. They can be electrically switched between low and high conductivity states that persist even in the absence of an applied voltage. In this way, these small blocks of nanoporous sugar function as a non‐volatile RRAM memory elements that can be repeatedly read, erased, and re‐written. These properties derive from ionic current within the MOF and the deposition of nanometer‐thin passivating layers at the anode flanking the MOF crystal. The observed phenomena are crucially dependent on the sub‐nanometer widths of the channels in the MOF, allowing the passage of only smaller ions. Conversely, with the electrolyte present but no MOF, there are no memristance or memory effects.
A Simple 3,4‐Ethylenedioxythiophene Based Hole‐Transporting Material for Perovskite Solar Cells
Authors: Li Hairong , Fu Kunwu , Hagfeldt Anders , Grätzel Michael , Mhaisalkar Subodh G. , Grimsdale Andrew C.
Published: March 2014

We report a novel electron‐rich molecule based on 3,4‐ethylenedioxythiophene (H101). When used as the hole‐transporting layer in a perovskite‐based solar cell, the power‐conversion efficiency reached 13.8 % under AM 1.5G solar simulation. This result is comparable with that obtained using the well‐known hole transporting material 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD). This is the first heterocycle‐containing material achieving >10 % efficiency in such devices, and has great potential to replace the expensive spiro‐OMeTAD given its much simpler and cheaper synthesis.
The combined effect of additives and processing on the thermal stability and controlled release of essential oils in antimicrobial films
Authors: Efrati Roni , Natan Michal , Pelah Avishay , Haberer Anina , Banin Ehud , Dotan Ana , Ophir Amos
Published: March 2014

Essential oils (EOs) have a long history as food preservatives and many advantages compared to synthetic preservatives. The major limitation of EOs as antimicrobial agents incorporated into a polymeric matrix is their low thermal stability and their high volatility from polymers. This study suggests a new methodology approach to bypass the key limitations of adding EOs into active packaging, as food preservatives. Antimicrobial active films based on linear low density polyethylene (LLDPE) and Montmorillonite (MMT) were produced by incorporating the EO thymol in a stepwise procedure. The production of the film composites, containing thymol, has been conducted, under a protocol of three stages: (1) production of a highly porous nano composite master batch; (2) impregnation of thymol into the master batch; and (3) cast film extrusion. Adding MMT incorporated together with a foaming agent at stage‐(1) increased significantly the heat stability of the EO during melt processing at stage‐(3). Finally, the film obtained showed a high antimicrobial activity. The results obtained have proven the synergistic interaction between MMT, foaming agent and thymol. As the MMT content in the film increased, the loss of EO in the processing decreased, leading to a natural antimicrobial film with improved antibacterial properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40564.
Effects of peroxide and gamma radiation on properties of devulcanized rubber/polypropylene/ethylene propylene diene monomer formulation
Authors: Hassan Medhat M. , Badway Nagwa A. , Elnaggar Mona Y. , Hegazy El‐Sayed A.
Published: March 2014

Mechanical and thermal properties of devulcanized rubber (DR)/polypropylene (PP)/ethylene propylene diene monomer blends (EPDM) were studied at various concentrations of dicumyl peroxide (DCP) and gamma radiation doses. The blends showed improved mechanical properties for vulcanized sample. The coupling of DR/PP/EPDM with different proportions of DCP was investigated by X‐ray diffraction and scanning electron microscopy techniques. Evaluation of the developed blends, unirradiated and gamma irradiated, was carried out using elastic modulus, tensile strength, elongation at break, thermogravimetric analysis, kinetic analysis, and DSC measurements. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40611.
Preparation and functional evaluation of agarose derivatives
Authors: Chaudhary Jai Prakash , Kondaveeti Stalin , Gupta Vishal , Prasad Kamalesh , Meena Ramavatar
Published: March 2014

A facile microwave‐assisted one‐pot synthesis of sodium carboxymethylagarose and calcium carboxymethylagarose from Gracilaria dura agarose (Ag) has been described. The process is user friendly, and the highest degree of substitution was obtained within 15 min compared with the conventional method, which requires more than 3 h. Solubility and gelling behavior of the modified Ag products were found to be dependent on degree of substitution of the products. The characterizations were done by using Fourier transform infrared spectroscopy, 1H‐ and 13C‐nuclear magnetic resonance spectroscopy, thermogravimetric analysis, scanning electron microscopy, Inductively coupled plasma spectrophotometry (ICP), rheology, conductometer analysis, and DNA gel electrophoresis. These agarose derivatives were easily soluble in water and exhibited low thermal hysteresis, improved conductivity, and improved the DNA resolution ability of the parent G. dura Ag hydrogels. These hydrogels may have potential applications in the areas including electrochemical devices, microbiology, biomedical, and pharmaceuticals fields. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40630.
Synthesis of Some Novel 1,2,4‐Triazol‐3‐one Derivatives Bearing the Salicyl Moiety and Their Anticonvulsant Activities
Authors: Kahveci Bahittin , Menteşe Emre , Akkaya Emre , Yılmaz Fatih , Doğan İnci S. , Özel Arzu
Published: March 2014

A series of new 1,2,4‐triazole‐3‐one derivatives bearing the salicyl moiety were synthesized by using microwave irradiation, and their chemical structures were identified by IR, 1H NMR, 13C NMR, elemental analysis, and LC‐MS. The anticonvulsant activities of the compounds 4a–c, 4e, and 5a–e were evaluated by the Anticonvulsant Screening Program of the National Institute of Health, USA. The compounds had moderate anticonvulsant activities in the maximum electroshock‐induced seizure and minimal clonic seizure models in mice, without any neurotoxic effects.
Synthesis and Anticancer Evaluation of Furfurylidene 4‐Piperidone Analogs
Authors: Jadhav Rahul L. , Magdum Chandrakant S. , Patil Manisha V.
Published: March 2014

Recently different series of compounds have been designed that utilize the 1,5‐diaryl‐3‐oxo‐1,4‐pentadinenyl pharmacophore for the development of novel cytotoxic and anticancer agents. These compounds interact with cellular thiols and thiols are not part of nucleic acids. Hence, these compounds are free from the problem of mutagenicity and carcinogenicity. The Claisen–Schmidt reaction is used for synthesizing furfurylidene analogs in a basic medium. The title compounds were prepared by reacting furfurylidenes with aryl sulfonyl, benzoyl, acroylyl, or acetyl chloride. The resulting synthesized compounds were screened for their in vitro cytotoxic properties by MTT and SRB assays against leukemic and colon cancer cell lines. Acute toxicity was determined by OECD‐423 guidelines. The in vivo anticancer activities were evaluated against Ehrlich ascites carcinoma (EAC)‐bearing Swiss albino mice. The MTT assay showed that compounds 2d and 3d have significant cytotoxicity against the Molt‐4 human cell line as compared to the standard, 5‐fluorouracil. In addition, the SRB assay indicated that the compounds 2, 2a, 2d, and 3d showed equipotent cytotoxicity against human leukemia cell lines as compared to the standard, doxorubicin. Compounds 2a and 2d showed significant anticancer activity against EAC in Swiss albino mice. This study revealed the potential of these molecules for further development as anticancer agents.
Investigating Construction History, Labour Investment and Social Change at Ocmulgee National Monument's Mound A, Georgia, USA, Using Ground‐penetrating Radar
Authors: Bigman Daniel P. , Lanzarone Peter M.
Published: March 2014

Prehistoric societies from around the world constructed monumental mounded architecture (earthen pyramids) for a variety of functions, including the foundation for temples or a leader's residence, community stages and cemeteries. Flat‐topped earthen mounds often have complicated histories where the function, size, orientation and summit architecture varied throughout time. This paper presents the results from a ground‐penetrating radar (GPR) survey conducted on the summit of Mound A, the largest prehistoric Native American mound at Ocmulgee National Monument located in central Georgia, USA. Our study indicates that performing depth‐slice analyses of flat‐topped mounds can effectively map successive construction stages over distinct periods of archaeological prehistory. The GPR data show distinctive low‐amplitude, discontinuous stratigraphic variations that we interpret to be related to mound fill, which are interrupted by high‐amplitude coherent summit reflections. We also maintain sufficient vertical and horizontal resolution to identify summit architecture on earlier mound‐use episodes, which is imaged by distinct reflection geometry as patterned linear, square and circular high‐amplitude events in GPR depth‐slices. The authors recorded four possible mound summits, the western expansion of the mound, and the shifting location and shape of summit architecture; in addition to resolving a discrepancy regarding the location of early excavation units from the 1930s. Shallow geophysical data indicate a decline in the volume of material used over the course of mound construction, and by inference, a decline in the size of the labour force used to construct each stage. We conclude that the power and influence of Ocmulgee's early leadership subsided over the course of Mound A's use, and may have been contested by an emerging faction. Copyright © 2014 John Wiley & Sons, Ltd.
Para-aortic lymph node sampling in pancreatic head adenocarcinoma
Authors: Schwarz L , Lupinacci R M , Svrcek M , Lesurtel M , Bubenheim M , Vuarnesson H , Balladur P , Paye F
Published: March 2014

Background

The significance of positive para-aortic nodes in patients with resectable pancreatic carcinoma is unclear. This study sought to evaluate the accuracy of intraoperative detection and prognostic significance of these lymph nodes in patients with resected adenocarcinoma of the pancreatic head.

Methods

From 2000 to 2010, para-aortic node sampling was performed prospectively in all patients before pancreatoduodenectomy. Frozen sections were created and nodes categorized as positive or negative for metastases. Surgeons were blinded to the frozen-section results. This was followed by standard histopathological assessment of corresponding paraffin-embedded, haematoxylin and eosin-stained material. Nodes considered uninvolved by this analysis were examined immunohistochemically for micrometastases.

Results

A total of 111 consecutive patients were included, with a median follow-up of 20·8 (range 1·5–126) months. The 1-, 2- and 5-year overall survival (OS) and disease-free survival (DFS) rates were 73·6, 54·0 and 24·7 per cent, and 51·8, 28·1 and 18·8 per cent respectively. Para-aortic node involvement was always associated with peripancreatic lymph node metastasis, and was detected by frozen-section analysis in 12 patients and by haematoxylin and eosin staining in 17. Sensitivity and specificity of frozen-section examination for detecting para-aortic lymph node metastases were 71 and 100 per cent respectively. Median OS for patients with and without para-aortic node involvement on frozen-section analysis was 9·7 versus 28·5 months respectively (P = 0·012), and 15·7 versus 27·2 months (P = 0·050) when assessed by haematoxylin and eosin staining. Median DFS for patients with and without para-aortic node involvement on frozen-section examination was 5·6 versus 12·9 months respectively (P = 0·041), and 8·4 versus 12·9 months (P = 0·038) for haematoxylin and eosin analysis. The presence of micrometastases in para-aortic nodes was not significantly associated with altered OS or DFS.

Conclusion

Para-aortic node sampling with frozen-section examination detects distant lymphatic involvement reliably. It should be performed systematically. When metastases are found, they should be considered a contraindication to pancreatic resection.
Alterations in empathic responding among women with posttraumatic stress disorder associated with childhood trauma
Authors: Parlar Melissa , Frewen Paul , Nazarov Anthony , Oremus Carolina , MacQueen Glenda , Lanius Ruth , McKinnon Margaret C.
Published: March 2014

Objective

Although studies increasingly point toward problems with social cognition among individuals with posttraumatic stress disorder (PTSD), few studies have assessed empathic responding. The aim of the current study was to investigate empathic responding in women with PTSD related to childhood trauma, and the contribution of parental bonding to empathic abilities in this sample.

Methods

Participants with PTSD (n = 29) and sex‐ and age‐matched healthy controls (n = 20) completed two self‐report empathy measures, the Interpersonal Reactivity Index (IRI) and the Toronto Empathy Questionnaire (TEQ), and a self‐report measure of attachment, the Parental Bonding Instrument (PBI).

Results

Women with PTSD, relative to controls, reported significantly lower levels of empathic concern (r = 0.29) and perspective taking (r = 0.30), yet significantly higher levels of personal distress (r = 0.45) on the IRI. Women with PTSD also reported elevated scores on the TEQ (η2 = 0.13). Levels of paternal care on the PBI, rather than childhood trauma severity or PTSD symptom severity best predicted perspective taking scores on the IRI in the PTSD sample (R2 = 0.20).

Conclusion

Women with PTSD associated with childhood trauma reported alterations among different domains of empathic functioning that may be related to low levels of paternal care.
Endotoxin inactivation via steam‐heat treatment in dilute simethicone emulsions used in biopharmaceutical processes
Authors: Britt Keith A. , Galvin Jeffrey , Gammell Patrick , Nti‐Gyabaah Joseph , Boras George , Kolwyck David , Ramirez José G. , Presente Esther , Naugle Gregory
Published: March 2014

Simethicone emulsion is used to regulate foaming in cell culture operations in biopharmaceutical processes. It is also a potential source of endotoxin contamination. The inactivation of endotoxins in dilute simethicone emulsions was assessed as a function of time at different steam temperatures using a Limulus amebocyte lysate kinetic chromogenic technique. Endotoxin inactivation from steam‐heat treatment was fit to a four‐parameter double exponential decay model, which indicated that endotoxin inactivation was biphasic, consisting of fast and slow regimes. In the fast regime, temperature‐related effects were dominant. Transitioning into the slow regime, the observed temperature dependence diminished, and concentration‐related effects became increasingly significant. The change in the Gibbs free energy moving through the transition state indicated that a large energy barrier must be overcome for endotoxin inactivation to occur. The corresponding Arrhenius pre‐exponential factor was >>1012 s−1 suggesting that endotoxins in aqueous solution exist as aggregates. The disorder associated with the endotoxin inactivation reaction pathway was assessed via the change in entropy moving through the transition state. This quantity was positive indicating that endotoxin inactivation may result from hydrolysis of individual endotoxin molecules, which perturbs the conformation of endotoxin aggregates, thereby modulating the biological activity observed. Steam‐heat treatment decreased endotoxin levels by 1–2 logarithm (log) reduction (LRV), which may be practically relevant depending on incoming raw material endotoxin levels. Antifoam efficiency and cell culture performance were negligibly impacted following steam‐heat treatment. The results from this study show that steam‐heat treatment is a viable endotoxin control strategy that can be implemented to support large‐scale biopharmaceutical manufacturing. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:1145–1160, 2014
Carbonate Linkage Bearing Naphthalenediimides: Self‐Assembly and Photophysical Properties
Authors: Kulkarni Chidambar , George Subi J.
Published: March 2014

Self‐assembly of carbonate linkage bearing naphthalene diimides (NDI) showed unusually red‐shifted excimer emission at approximately 560 nm. On the other hand, the ether linkers showed usual excimers at around 520 nm, highlighting the role of the carbonate group in tuning the molecular organization and the resultant photophysical properties of NDI.
Baseline serum albumin is a predictive biomarker for patients with advanced pancreatic cancer treated with bevacizumab: A pooled analysis of 7 prospective trials of gemcitabine‐based therapy with or without bevacizumab
Authors: Pant Shubham , Martin Ludmila K. , Geyer Susan , Wei Lai , Van Loon Katherine , Sommovilla Nilli , Zalupski Mark , Iyer Renuka , Fogelman David , Ko Andrew H. , Bekaii‐Saab Tanios
Published: March 2014

BACKGROUND

Phase 3 studies of bevacizumab in patients with advanced pancreatic cancer (APCA) demonstrated no improvement in outcome. To the authors' knowledge, no validated predictive biomarkers for bevacizumab exist, although emerging data suggest that subsets of patients with APCA may benefit from treatment with bevacizumab. The authors evaluated baseline serum albumin (b‐alb) as a predictive biomarker in a pooled analysis from 7 prospective clinical trials of gemcitabine‐based therapy with or without bevacizumab.

METHODS

Data were collected from individual databases from 7 prospective clinical trials. Patients were grouped by exposure to bevacizumab and by b‐alb level (≥ 3.4 g/L or < 3.4 g/dL). Overall survival (OS), time to disease progression (TTP), overall response rate, and disease control rate (overall response rate plus stable disease lasting ≥ 16 weeks) were compared between groups. Univariate and multivariable analyses of prognostic factors were performed.

RESULTS

A total of 264 patients were included. The median age was 59 years (range, 31 years‐85 years) and all patients had stage IV disease per TNM staging. Normal b‐alb was associated with significantly improved median OS (10.2 months vs 4.1 months; P = .0001), median TTP (6.2 months vs 3.7 months; P = 0.0488), and disease control rate (71% vs 46%; P = .007) for patients receiving bevacizumab, but not for those treated without bevacizumab. Multivariable analysis revealed a significant influence of normal b‐alb on OS (P = .0008) and TTP (P = .033).

CONCLUSIONS

Patients with APCA with normal b‐alb derive benefit from treatment with bevacizumab. Future prospective investigations of bevacizumab in patients with APCA should consider selecting patients with normal b‐alb to maximize potential benefit. Cancer 2014;120:1780–1786. © 2014 American Cancer Society.
Correlation of fundamental photoreflectance spectra with surface quality of bulk ZnTe semiconductor grown from Te solution
Authors: Yang Rui , Jie Wanqi , Xu Yadong
Published: March 2014

Large size ZnTe single crystals were grown from Te‐solution with the vertical Bridgman method. The fundamental photoreflectance (PR) spectra of bulk ZnTe crystal subjected to a successive sequence of surface treatments, i.e., mechanical and chemical polishing, and passivation, have been measured over the wavelength range 200–600 nm at room temperature (RT) for the first time. The shape, relative intensity and evolution of the distinct E0, E1, E1+∆1 and E2 transitions during each stage of wafer processing were investigated. It was found that, those distinct transitions vary with varying crystal surface quality. The intensity of the reflectance peaks is large with sharp peak profile when the surface has good crystalline quality. However, E0 peak can be easily eliminated by a small amount of structural damages on the wafer surface. The dispersion tendency of the E1 and E1+∆1 peaks suggesting the wafer surface is widespread covered by structural damages. The reflection peaks’ intensity were all reduced after passivated with H2O2 solution. E2 peak intensity is more easily to be reduced during passivation.
High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands
Authors: Hawkes Lucy A. , McGowan Andrew , Broderick Annette C. , Gore Shannon , Wheatley Damon , White Jim , Witt Matthew J. , Godley Brendan J.
Published: March 2014

Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture–mark–recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year−1 (range 2.3–20.3 cm year−1), and gained mass at an average of 3.9 kg year−1 (range 850 g–16.1 kg year−1). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51–69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered.