Numerical Routines for the Optimization of Pump Power and Wavelength in Distributed Raman Amplifiers

We present optimization routines developed to define rapidly and precisely the best pump wavelengths and powers for distributed Raman amplifier design. We confirm the validity of our method through simulations by solving the full propagation equations, which govern the amplifier behavior. The sensitivity of the results obtained on the target bandwidth and on the correct selection of the pump wavelengths is studied. Finally, we compare the efficiency of the presented method in relation to previously presented algorithms.     

Cyclodextrins as a chiral mobile phase additive in nano-liquid chromatography: comparison of reversed-phase silica monolithic and particulate capillary columns

Enantioseparations of racemic nonsteroidal anti-inflammatory drugs (naproxen, ibuprofen, ketoprofen, flurbiprofen, suprofen, indoprofen, cicloprofen, and carprofen) were performed by nano-liquid chromatography, employing achiral capillary columns and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD) or hydroxylpropyl-β-cyclodextrin (HP-β-CD) as a chiral mobile phase additive (CMPA). Working under the same experimental conditions (in terms of mobile phase and linear velocity), the performance of a RP-C18 monolithic column was compared with that of a RP-C18 packed column of the same dimensions (100 μm i.d. × 10 cm). Utilizing a mobile phase composed of 30% ACN (v/v) buffered with 50 mM sodium acetate at pH 3, and containing 30 mM TM-β-CD, the monolithic column provided faster analysis but lower resolution than the packed column. This behavior was ascribed to the high permeability of the monolithic column, as well as to its minor selectivity. HP-β-CD was chosen as an alternative to TM-β-CD. Employing the monolithic column, the effects of different parameters such as HP-β-CD concentration, mobile phase composition, and pH on the retention factor and the chiral resolution of the analytes were studied. For the most of the analytes, enantioresolution (which ranged from R _s = 1.80 for naproxen to R _s = 0.86 for flurbiprofen) was obtained with a mobile phase consisting of sodium acetate buffer (25 mM, pH 3), 10% MeOH, and 15 mM HP-β-CD. When the same experimental conditions were used with the packed column, no compound eluted within 1 h. Upon increasing the percentage of organic modifier to favor analyte elution, only suprofen eluted within 30 min, with an R _s value of 1.14 (20% MeOH). Replacing MeOH with ACN resulted in a loss of enantioresolution, except for naproxen (R _s = 0.89).     

Protein thioester synthesis enabled by sortase

Proteins containing a C-terminal thioester are important intermediates in semisynthesis. Currently there is one main method for the synthesis of protein thioesters that relies upon the use of engineered inteins. Here we report a simple strategy, utilizing sortase A, for routine preparation of recombinant proteins containing a C-terminal (α)thioester. We used our method to prepare two different anthrax toxin cargo proteins: one containing an (α)thioester and another containing a D-polypeptide segment situated between two protein domains. We show that both variants can translocate through protective antigen pore. This new method to synthesize a protein thioester allows for interfacing of sortase-mediated ligation and native chemical ligation.     

Upper rim guanidinocalix[4]arenes as artificial phosphodiesterases

Calix[4]arene derivatives, blocked in the cone conformation and functionalized with two to four guanidinium units at the upper rim were synthesized and investigated as catalysts in the cleavage of the RNA model compound 2-hydroxypropyl p-nitrophenyl phosphate. When compared with the behavior of a monofunctional model compound, the catalytic superiority of the calix[4]arene derivatives points to a high level of cooperation between catalytic groups. Combination of acidity measurements with the pH dependence of catalytic rates unequivocally shows that a necessary requisite for effective catalysis is the simultaneous presence, on the same molecular framework, of a neutral guanidine acting as a general base and a protonated guanidine acting as an electrophilic activator. The additional guanidinium (guanidine) group in the diprotonated (monoprotonated) trifunctional calix[4]arene acts as a more or less innocent spectator. This is not the case with the tetrasubstituted calix[4]arene, whose mono-, di-, and triprotonated forms are slightly less effective than the corresponding di- and triguanidinocalix[4]arene derivatives, most likely on account of a steric interference with HPNP caused by overcrowding.     

FT-ICR-MS analysis of lignin

Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) of a steam-exploded lignin from wheat straw showed that fragments with a mass higher than 4534?Da cannot be obtained. Furthermore, FT-ICR-MS showed that lignin is not a completely random polymer, but shows some regularity with a difference of 44.026?m/z (C?H?O) between the peaks. The distribution of Kendrick mass defect in the function of Kendrick nominal masses showed the same behaviour. FT-ICR-MS analysis of bagasse lignin (Granit) showed that the largest value of mass found was 4347?Da. The peaks show regularities with a difference of 44.026?m/z between the peaks. The organosolv lignin showed that the polymer with the largest mass value was 3699?Da in FT-ICR-MS. The analysis of the peaks did not show regularity; however, the Kendrick diagram for this lignin showed the same slope as in the other samples, in agreement with the C?H?O regular difference between peaks.     

Fractional dimension of binary Knuth semifield planes

We prove that semifield planes π(??_2m) coordinatized by the commutative binary Knuth semifield ??_2m, m = nk ( m odd) are fractional dimensional with respect to a subplane isomorphic to PG ( 2 , 4 ) if either n = 9 or n ≡\ 0 ( mod 3 ) and one of the trinomials x ⁿ + x ^s + 1 , s ∈{ 1 , 2 , 3 , 5 }, is irreducible over the Galois field ?? ₂ . © 2012 Wiley Periodicals, Inc. J. Combin. Designs 20: 317–327, 2012     

Equations Defining Symmetric Varieties and Affine Grassmannians

Suppose be a simpleinvolution of a semisimple algebraic group and suppose H is the subgroup of G of pointsfixed by . If the restrictedroot system is of type or and G is simplyconnected, or if the restricted root system is of type and G is of adjoint type, then we describe astandard monomial theory and the equations for the coordinatering using the standardmonomial theory and the Plücker relations of an appropriate(maybe infinite-dimensional) Grassmann variety.     

Performance evaluation of mapping and linear imaging FTIR microspectroscopy for the characterisation of paint cross sections

Different Fourier transform infrared microspectroscopic techniques, using attenuated total reflection (ATR) mode and single-element mercury–cadmium–telluride (MCT) detector (mapping) or multielement MCT detector (raster scanning), are compared with each other for the characterisation of inorganic compounds and organic substances in paint cross sections. All measurements have been performed on paint cross sections embedded in potassium bromide, a transparent salt in the mid-infrared region, in order to better identify the organic materials without the interference of the usual embedding resin. The limitations and advantages of the different techniques are presented in terms of spatial resolution, data quality and chemical information achieved. For all techniques, the chemical information obtained is found to be nearly identical. However, ATR mapping performed with a recently developed instrumentation shows the best results in terms of spectral quality and spatial resolution. In fact, thin organic layers (∼10 μm) have been not only identified but also accurately located. This paper also highlights the recent introduction of multielement detectors, which may represent a good compromise between mapping and imaging systems.     

Evaluation of the effects of gamma radiation on thermal properties of wood species used in Brazilian artistic and cultural heritage

The wood is considered a natural composite of extreme complexity, mainly composed of cellulose, lignin, hemicellulose (polyposis), and extractives. Its composition encourages biological attacks from different species. In this context, several techniques have been studied and applied for disinfecting and decontaminating wood-made works of art and cultural heritage objects, which have been damaged by fungi, bacteria, and insects. Gamma radiation has been studied as an alternative to chemical methodologies for this purpose. By this way, the aim of this article is to illustrate the effect of gamma radiation on some physicochemical properties of Pinnus patula, Pinnus cunninghamia, Cedrella fissillis, and Ocotea porosa wood species. The irradiation has shown itself to be a fast and efficient process to eliminate infestations by both insects and microorganisms and no quarantine is required because of the no generation of toxic residues. On the other hand, this process does not protect the irradiated material from re-infestations or re-contamination. In this study, relatively high gamma radiation doses were applied up to 100 kGy so that radiation effects, which are cumulative, could be retrieved by means of thermal properties. The results have shown that gamma radiation, in the studied dose range, does not promote meaningful alterations on the evaluated properties, which allows that artifacts be irradiated multiple times, even if a re-infestation occurs.