The distribution of the number of points modulo an integer on elliptic curves over finite fields

Let $\mathbb{F}_{q}$ be a finite field, and let b and N be integers. We prove explicit estimates for the probability that the number of rational points on a randomly chosen elliptic curve E over $\mathbb{F}_{q}$ equals b modulo N. The underlying tool is an equidistribution result on the action of Frobenius on the N-torsion subgroup of E. Our results subsume and extend previous work by Achter and Gekeler.     

Identification and Directed Development of Non‐Organic Catalysts with Apparent Pan‐Enzymatic Mimicry into Nanozymes for Efficient Prodrug Conversion

Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of the Origin of Life. However, current nanozymes offer mimicry of a narrow range of mammalian enzymes, near‐exclusively performing redox reactions. We present an unexpected discovery of non‐proteinaceous enzymes based on metals, metal oxides, 1D/2D‐materials, and non‐metallic nanomaterials. The specific novelty of these findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan‐glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme‐prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti‐inflammatory and antibacterial agents, as well as “nanozyme prodrug therapy” to mediate antibacterial measures.     

Extreme Lagrangian acceleration in confined turbulent flow

A Lagrangian study of two-dimensional turbulence for two different geometries, a periodic and a confined circular geometry, is presented to investigate the influence of solid boundaries on the Lagrangian dynamics. It is found that the Lagrangian acceleration is even more intermittent in the confined domain than in the periodic domain. The flatness of the Lagrangian acceleration as a function of the radius shows that the influence of the wall on the Lagrangian dynamics becomes negligible in the center of the domain, and it also reveals that the wall is responsible for the increased intermittency. The transition in the Lagrangian statistics between this region, not directly influenced by the walls, and a critical radius which defines a Lagrangian boundary layer is shown to be very sharp with a sudden increase of the acceleration flatness from about 5 to about 20.     

An integrated QCM-based narcotics sensing microsystem

We present the design, fabrication and successful testing of a 14x14x4 mm3 integrated electronic narcotics sensing system which consists of only four parts. The microsystem absorbs airborne narcotics molecules and performs a liquid assay using an integrated quartz crystal microbalance (QCM). A vertically conductive double-sided adhesive foil (VCAF) was used and studied as a novel material for LOC and MEMS applications and provides easy assembly, electrical contacting and liquid containment. The system was tested for measuring cocaine and ecstasy, with successful detection of amounts as small as 100 ng and 200 ng, respectively. These levels are of interest in security activities in customs, prisons and by the police.     

Energetics and role of the hydrophobic interaction during photoreaction of the BLUF domain of AppA

A recently developed method for time-resolved thermodynamic measurements was used to study the photochemical reaction(s) of the BLUF domain of AppA (AppA-BLUF), which has a dimeric form in the ground state, in terms of the energetics and heat capacity changes (DeltaC(p)) in different time domains. The enthalpy change (DeltaH) of the first intermediate that forms within 1 ns after photoexcitation was 38 (+/-8) kJ mol(-1) at 298 K. The heat capacity change (DeltaC(p)) upon formation of this intermediate was positive [1.4 (+/-0.3) kJ mol(-1) K(-1)]. This positive DeltaC(p) suggests that the hydrophobic surface area of AppA-BLUF exposed to the bulk solvent increased. After this initial transition, a dimerization reaction with another ground-state dimer (i.e., tetramer formation) takes place. Upon this reaction, the energy was stabilized to 26 (+/-6) kJ mol(-1) at 298 K. Interestingly, the dimer formation was accompanied by a larger but negative DeltaC(p) [-6.0 (+/-1) kJ mol(-1) K(-1)]. This negative DeltaC(p) might indicate buried hydrophobic residues at the interface of the dimer and/or the existence of trapped water at the interface. We suggest that hydrophobic interactions are the main driving force for the formation of the dimer upon photoactivation of AppA-BLUF.     

Identification of six new photoactive yellow proteins--diversity and structure-function relationships in a bacterial blue light photoreceptor

Photoactive yellow proteins (PYP) are bacterial photoreceptors with a Per-Arnt-Sim (PAS) domain fold. We report the identification of six new PYPs, thus nearly doubling the size of this protein family. This extends the taxonomic diversity of PYP-containing bacteria from photosynthetic to nonphotosynthetic bacteria, from aquatic to soil-dwelling organisms, and from Proteobacteria to Salinibacter ruber from the phylum Bacteriodetes. The new PYPs greatly increase the sequence diversity of the PYP family, reducing the most prevalent pair-wise identity from 45% to 25%. Sequence alignments and analysis indicate that all 14 PYPs share a common structure with 13 highly conserved residues that form the chromophore binding pocket. Nevertheless, the functional properties of the PYPs vary greatly--the absorbance maximum extends from 432 to 465 nm, the pK(a) of the chromophore varies from pH 2.8 to 10.2, and the lifetime of the presumed PYP signaling state ranges from 1 ms to 1 h. Thus, the PYP family offers an excellent opportunity to investigate how functional properties are tuned over a wide range, while maintaining the same overall protein structural fold. We discuss the implications of these results for structure-function relationships in the PYP family.     

Quantitative analysis of metabolites in complex biological samples using ion-pair reversed-phase liquid chromatography-isotope dilution tandem mass spectrometry

A rapid, sensitive and selective ion-pair reversed-phase liquid chromatography-electrospray ionization isotope dilution tandem mass spectrometry (IP-LC-ESI-ID-MS/MS) was developed for quantitative analysis of free intracellular metabolites in cell cultures. As an application a group of compounds involved in penicillin biosynthesis pathway of Penicillium chrysogenum cells, such as penicillin G (PenG), 6-aminopenicillanic acid (6-APA), benzylpenicilloic acid (PIO), ortho-hydroxyphenyl acetic acid (o-OH-PAA), phenylacetic acid (PAA), 6-oxopipeidine-2-carboxylic acid (OPC), 8-hydroxypenicillic acid (8-HPA), L-alpha-(delta-aminoadipyl)-L-alpha-cystenyl-D-alpha-valine (ACV) and isopenicillin N (IPN) were chosen. (13)C-labeled analogs of the metabolites were added to the sample solutions as internal standards (I.S.). Sample mixtures were analyzed without any sample pretreatment. No extraction recovery check was needed because I.S. was added to the cell samples before extraction process. The method showed excellent precision (relative standard deviation (RSD)相似文献   

PVC Supported Liquid Membrane and Carbon Paste Potentiometric Sensors Incorporating a Mn(III)‐Porphyrin for the Direct Determination of Undissociated Paracetamol

PVC supported liquid membrane and carbon paste potentiometric sensors incorporating an Mn(III)‐porphyrin complex as a neutral host molecule were developed for the determination of paracetamol. The measurements were carried out in solution at pH 5.5. Under such conditions paracetamol exists as a neutral molecule. The mechanism of molecular recognition between the Mn(III)‐porphyrin and paracetamol, leading to potentiometric signal generation, is discussed.     

Metergoline II: structure solution from powder diffraction data with preferred orientation and from microcrystal

Metergoline is a dopamine agonist and serotonin antagonist used both in human and veterinary medicine. In addition to the previously known crystalline form, a new polymorph, which crystallizes from aqueous solution, was found. Since it was initially impossible to prepare a single crystal of quality suitable for single crystal X-ray diffraction measurements using a conventional laboratory source, the structure was solved from the powder diffraction data using synchrotron radiation. The structure determination also included solving the effects of preferred orientation. Characterization was simultaneously done by solid-state NMR spectroscopy. Finally, a small single crystal suitable for synchrotron diffraction was found after numerous tries. Crystal structure determination using this single crystal confirmed the powder-based solution. Comparison of information obtained by different experimental methods (powder diffraction, ssNMR, single crystal diffraction) was made.     

Flow cytometric immunoassay for sulfonamides in raw milk

Sulfonamide antibiotics are applied in veterinary medicine for the treatment of microbial infections. For the detection of residues of sulfonamides in milk, a multi-sulfonamide flow cytometric immunoassay (FCI) was developed using the Luminex MultiAnalyte Profiling (xMAP) technology. In this automated FCI, a previously developed biotinylated multi-sulfonamide mutant antibody (M.3.4) was applied in combination with fluorescent beads, directly coated with a sulfathiazole derivative, and streptavidin–phycoerythrin (SAPE) for the detection. With this FCI, at least 11 different sulfonamides could be detected (more than 50% inhibition at the 100 ng mL⁻¹ level) and, after an incubation of 1 h, measurements were rapid (10 s per sample). For the application with raw milk, a 96-well microplate-based filtration step was included into the protocol to remove disturbing milk fat particles. Because of differences in sensitivity towards different sulfonamides, the FCI was considered and validated as a qualitative screening assay. For sulfadoxine, the most applied sulfonamide in Dutch dairy cattle, the detection capability (CCβ) was <50 μg L⁻¹ and this level seems feasible for five other sulfonamides. For sulfadiazine, the CCβ was <200 μg L⁻¹ and this level seems feasible for four other sulfonamides. A major advantage of the applied xMAP-technology, with its 100 different color-coded bead sets, is the possibility to develop multiplex immunoassays for the simultaneous detection of several antibiotics.