Dimensional regularization at finite temperature

Quasi-primary fields with dimensions that differ at most byO(1/N) and whose other quantum numbers are all equal, are called degenerate. Multiplets of such fields are produced by a chain of fusion processes. Forcing the fusion to run through different intermediate states leads to matrices of fusion and anomalous dimension amplitudes whose simultaneous diagonalization allows to resolve the degeneracy.     

Chemical investigation of metabolites produced by an endophytic Aspergillus sp. isolated from Limonia acidissima

Endophytic fungi are considered as a good source to produce important secondary metabolites with interesting bioactivities. In a continuation of our studies towards the search for environmentally friendly bioactive compounds from Sri Lankan flora, we investigated the secondary metabolites produced by the endophytic fungi Aspergillus sp. isolated from the seeds of the popular edible fruit Limonia acidissima L. of the family Rutaceae. The pure culture of the Aspergillus sp. was grown on potato dextrose broth media. After 4 weeks fermentation, fungal media were extracted with organic solvents. Chromatographic separation of the fungal extracts over silica gel, Sephadex LH-20 and RP-HPLC furnished flavasperone (1), rubrofusarin B (2), aurasperone A (3), fonsecinone D (4) and aurasperone B (5). Compounds 1–4 showed moderate activities in brine shrimp toxicity assay. This is the first report of the ¹³C NMR data of compounds 4 and 5.     

Quantitative Proteomic Analysis of Optimal Cutting Temperature (OCT) Embedded Core-Needle Biopsy of Lung Cancer

With recent advances in understanding the genomic underpinnings and oncogenic drivers of pathogenesis in different subtypes, it is increasingly clear that proper pretreatment diagnostics are essential for the choice of appropriate treatment options for non-small cell lung cancer (NSCLC). Tumor tissue preservation in optimal cutting temperature (OCT) compound is commonly used in the surgical suite. However, proteins recovered from OCT-embedded specimens pose a challenge for LC-MS/MS experiments, due to the large amounts of polymers present in OCT. Here we present a simple workflow for whole proteome analysis of OCT-embedded NSCLC tissue samples, which involves a simple trichloroacetic acid precipitation step. Comparisons of protein recovery between frozen versus OCT-embedded tissue showed excellent consistency with more than 9200 proteins identified. Using an isobaric labeling strategy, we quantified more than 5400 proteins in tumor versus normal OCT-embedded core needle biopsy samples. Gene ontology analysis indicated that a number of proliferative as well as squamous cell carcinoma (SqCC) marker proteins were overexpressed in the tumor, consistent with the patient’s pathology based diagnosis of “poorly differentiated SqCC”. Among the most downregulated proteins in the tumor sample, we noted a number of proteins with potential immunomodulatory functions. Finally, interrogation of the aberrantly expressed proteins using a candidate approach and cross-referencing with publicly available databases led to the identification of potential druggable targets in DNA replication and DNA damage repair pathways. We conclude that our approach allows LC-MS/MS proteomic analyses on OCT-embedded lung cancer specimens, opening the way to bring powerful proteomics into the clinic.

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DNA-binding small-ligand-immobilized surface plasmon resonance biosensor for detecting thymine-related single-nucleotide polymorphisms

A surface plasmon resonance (SPR) biosensor that carries DNA-binding small ligands has been developed for the detection of single-nucleotide polymorphisms (SNPs). 3,5-Diaminopyrazine derivatives, with a hydrogen-bonding profile fully complementary to the thymine base, were utilized as recognition elements on the sensor surface, and a target single-stranded DNA sequence was hybridized with a DNA probe containing an abasic site to place this site opposite a nucleobase to be detected. In a continuous flow of sample solutions buffered to pH 6.4 (0.25 M NaCl), the 3,5-diaminopyrazine-based SPR sensor can detect an orphan nucleobase in the duplex with a clear selectivity for thymine over cytosine, guanine, and adenine (5'-GTT GGA GCT GXG GGC GTA GGC-3'/3'-CAA CCT CGA CNC CCG CAT CCG-5'; X=abasic site, N=target nucleobase G, C, A, or T). The SPR response was linear in the concentration range 10-100 nM. Allele discrimination is possible based on the combination of different binding surfaces in a flow cell of the SPR system, which is demonstrated for the analysis of the thymine/cytosine mutation present in 63-meric polymerase chain reaction (PCR) amplification products (Ha-ras gene, codon 12, antisense strand). Comparison with a bulk assay based on 3,5-diaminopyrazine/DNA binding shows that the immobilization of 3,5-diaminopyrazine derivatives on the SPR sensor allows more sensitive detection of the target DNA sequence, and binding selectivity can be tuned by controlling the salt concentration of sample solutions. These features of the DNA-binding small-molecule-immobilized SPR sensor are discussed as a basis for the design of SPR biosensors for SNP genotyping.     

Spectral properties of the Cu-hyperaccumulating moss Scopelophilacataractae

To determine the characteristics of a Cu-hyperaccumulating moss Scopelophilacataractae and the influence of Cu on its structure and on chlorophyll (Chl), we measured reflectance and fluorescence (FL) spectra of S.cataractae samples with different Cu concentrations before and after wetting and the absorption spectra of Chl extracted from these samples. We found relationships between the spectral properties and Cu concentration. These relationships can be explained as follows. The higher the Cu concentration is, the lower is the plasticity of the cell wall, and the smaller is the increase in illuminated area due to the opening of the leaves after wetting. This results in a smaller increase in absorption and smaller decrease in reabsorption of the FL by Chl itself, and accordingly, a smaller increase in the FL band of Chl after wetting. Moreover, we found that the Chl concentration in S.cataractae is much higher than that in other common mosses and is correlated with an increase in the FL band of Chl after wetting. The remarkable increase in FL seen in S.cataractae and the slight increase in FL observed in other common mosses after wetting can be explained based on these findings.     

Photoemission study on the valence band of a β-FeSi2 thin film using synchrotron radiation

Resonant and constant-initial state photoemission spectroscopies using synchrotron radiation were applied to investigate the valence-band electronic structure of a semi-conducting β-type iron-disilicide (β-FeSi(2)) thin film. The results clearly indicated that the component elements, iron (Fe) and silicon (Si), contribute differently to the valence band features; the Fe 3d orbitals mainly concentrate in the top region of the valence band while the Si 3s and 3p orbitals spread over the wide region of the valence band. The β-FeSi(2) thin film showed a typical p-type semi-conducting nature with a work function of 4.78 eV. The β-FeSi(2) film showed the Fe M(1)VV Auger lines around the kinetic energy of 88 eV. It would be expected from these observations that there exist strong interactions between iron and silicon atoms in the β-FeSi(2) film resulting in orbital mixing and band formation.     

Color tuning in photofunctional proteins

Depending on protein environment, a single photofunctional chromophore shows a wide variation of photoabsorption/emission energies. This photobiological phenomenon, known as color tuning, is observed in human visual cone pigments, firefly luciferase, and red fluorescent protein. We investigate the origin of color tuning by quantum chemical calculations on the excited states: symmetry-adapted cluster-configuration interaction (SAC-CI) method for excited states and a combined quantum mechanical (QM)/molecular mechanical (MM) method for protein environments. This Minireview summarizes our theoretical studies on the above three systems and explains a common feature of their color-tuning mechanisms. It also discuss the possibility of artificial color tuning toward a rational design of photoabsorption/emission properties.     

A rapid and economical method for profiling feature heights during microfabrication

Quality control is an important and integral part to any microfabrication process. While the widths of features often can be easily assessed by light microscopy, the heights of the fabricated structures are more difficult to determine. Here, we present a rapid, accurate, and low-cost method to measure the heights of microfabricated structures during and after the fabrication process. This technique is based on white-light interferometry, which offers accuracy on the submicrometre scale.