Ontogenetic skull variation in an Amazonian population of lowland tapir, Tapirus terrestris (Mammalia: Perissodactyla) in the department of Loreto, Peru

ABSTRACT The skulls of 54 specimens of the South American tapir, Tapirus terrestris collected in the department of Loreto, Peru were measured, analyzed and compared to investigate skull development of this species. Univariate, multivariate and allometric analyses were performed using 32 skull variables through traditional morphometrics. Significant skull shape variation was detected among ontogenetic classes. Young individuals (class I, n = 22) showed higher variation than subadults and adults (class II, n = 23 and class III, n = 9), without evidence of sexual dimorphism (males = 35, females = 19). Principal component analyses and discriminant function analysis showed almost complete separation of the age classes. Allometric analysis indicated a tendency of unproportioned cranial growth. All our samples come from the same population living under the same ecological condition, which eliminates the effect of confounding variables related to habitat on the pattern of ontogenetic variation of this anatomical structure.

Microscopic Kinetics in Poly(Methyl Methacrylate) Exposed to a Single Ultra-Short XUV/X-ray Laser Pulse

We study the behavior of poly(methyl methacrylate) (PMMA) exposed to femtosecond pulses of extreme ultraviolet and X-ray laser radiation in the single-shot damage regime. The employed microscopic simulation traces induced electron cascades, the thermal energy exchange of electrons with atoms, nonthermal modification of the interatomic potential, and a triggered atomic response. We identify that the nonthermal hydrogen decoupling triggers ultrafast fragmentation of PMMA strains at the absorbed threshold dose of ~0.07 eV/atom. At higher doses, more hydrogen atoms detach from their parental molecules, which, at the dose of ~0.5 eV/atom, leads to a complete separation of hydrogens from carbon and oxygen atoms and fragmentation of MMA molecules. At the dose of ~0.7 eV/atom, the band gap completely collapses indicating that a metallic liquid is formed with complete atomic disorder. An estimated single-shot ablation threshold and a crater depth as functions of fluence agree well with the experimental data collected.

A Research of Stereo-Selective Synthesis of Silica-based Amphiphilic Janus Particles

Because Janus particles with specific asymmetric nanostructures can be fixed in the oil phase or water respectively, they are more suitable for Pickering emulsion stability. Furthermore, the complete separation of hydrophobic and hydrophobic regions makes adjusting the hydrophobic/hydrophobic region ratio possible by changing the volume ratio. In this study, the preparations of three asymmetric silicon-based amphiphilic Janus nanoparticles are introduced. The methods used are consecutive immobilization, seed emulsion polymerization, and selective encapsulation, respectively. Complete compartmentalization of hydrophilic and hydrophobic domains was realized by anchoring silica with nucleation site, seed emulsion polymerization, or surface charge repulsion. In addition, these nanoparticles can be easily functionalized, bringing new research opportunities to applications in catalysis, adsorption, separation and biomedicine.

Study of the mechanism of pre-burned ash leaching by hydrochloric acid

The use of hydrochloric acid for processing aluminum-containing raw materials has a number of advantages over other acids, which include: easy decomposition of aluminum compounds with the transfer of aluminum into solution; low solubility of silica in HCl, the possibility of complete separation of the solid residue without significant losses of acid, etc. The paper considers the possibility of using the method for processing ash and slag dumps accumulated in large volumes in the country. Based on the thermodynamic analysis of reactions of interaction between ash components and hydrochloric acid, the behavior of aluminum, iron and nonferrous metal compounds during leaching is studied. It was shown that the preliminary roasting of ash with calcium chloride provides a high extraction of aluminum in the solution from the cinder. Based on experimental studies, the influence of time, temperature and acid consumption on the degree of aluminum extraction into the solution has been established. At optimal conditions of leaching conducted at S:L = 1:3, T = 60 ºC, τ = 60 min extraction of aluminum in a solution as chloride amounted to 99.92 %. At the same time the extraction of silica in solid sediment due to the maximum transfer of impurities in the solution was 99.8 %. The mechanism of the leaching process is proposed. The values of activation energy and the order of the reaction, indicating the complex 3-step character of the reactions, have been calculated. It is established that the limiting stage during leaching is the dissolution of anorthite.

Casing Integrity Evaluation in Complex Subsurface Intervention Abandonment Wells Using Magnetic Ranging

This paper describes how active and passive magnetic ranging logging used while drilling subsurface intervention wells shows characteristics of the target well casing integrity and damage. Over the course of the development of a novel active magnetic ranging system and through several years of commercial application, data has been collected and analyzed to understand the characteristics of casing damage. This paper explains the methods used in field operations to collect this data. Using the gathered information, various stages of casing damage and poor integrity are shown. Results obtained from active and passive magnetic ranging are presented in the context of identifying casing damage. This is a departure from the standard methods of interpreting the data as it is not focused on locating a wellbore but determining the integrity of the casing. Casing integrity in idle wells is usually understood by conventional logging techniques until there is a restriction or damage on the well. Magnetic ranging logging performed during the intervention to abandon these wells can give an indication to operators of the casing integrity that otherwise would have been unknown without access to the damaged well. This can help optimize subsequent abandonment procedures as well as assist with field planning into the future to mitigate issues stemming from casing integrity and to identify the causes of previously unknown critical casing damage. The paper reports surface experimental data and compares it with two field examples. In the first field example, the passive magnetic interference from a hundred-year-old casing in the offset well caused more than 100000nT deviation from the reference field approximately 1ft away from the offset well, suggesting severe casing damage. The active magnetic signature measured simultaneously approaches zero, pointing to a lack of electrical continuity in the offset casing caused by a complete break. The second field example shows an offset well segment with passive interference of 7000nT in the presence of a stable active magnetic signal at approximately 2ft separation between wells due to possible casing damage without complete separation. The passive interference increases to 14000 nT at deeper depth while the active signal approaches zero due to a complete casing break. Novel application using the data collected by active and passive magnetic ranging techniques is being applied for the understanding of issues related to casing integrity.

Preclinical development of a bispecific TNFα/IL-23 neutralising domain antibody as a novel oral treatment for inflammatory bowel disease

Anti-TNFα and anti-IL-23 antibodies are highly effective therapies for Crohn’s disease or ulcerative colitis in a proportion of patients. V56B2 is a novel bispecific domain antibody in which a llama-derived IL-23p19-specific domain antibody, humanised and engineered for intestinal protease resistance, V900, was combined with a previously-described TNFα-specific domain antibody, V565. V56B2 contains a central protease-labile linker to create a single molecule for oral administration. Incubation of V56B2 with trypsin or human faecal supernatant resulted in a complete separation of the V565 and V900 monomers without loss of neutralising potency. Following oral administration of V900 and V565 in mice, high levels of each domain antibody were detected in the faeces, demonstrating stability in the intestinal milieu. In ex vivo cultures of colonic biopsies from IBD patients, treatment with V565 or V900 inhibited tissue phosphoprotein levels and with a combination of the two, inhibition was even greater. These results support further development of V56B2 as an oral therapy for IBD with improved safety and efficacy in a greater proportion of patients as well as greater convenience for patients compared with traditional monoclonal antibody therapies.

Determination of Pyrrolizidine Alkaloids in Teas Using Liquid Chromatography–Tandem Mass Spectrometry Combined with Rapid-Easy Extraction

This study developed an analytical method to determine pyrrolizidine alkaloids (PAs) in teas using liquid chromatography–tandem mass spectrometry combined with rapid-easy extraction. PAs were extracted with 40 mL of 0.05 M sulfuric acid in 50% methanol solution and cleaned up using Oasis MCX SPE cartridges. Chromatographic separation of 21 PAs was conducted on an X-Bridge C18 column with gradient elution. According to the AOAC official analysis methods, the developed method was verified to establish linearity, limits of detection, limits of quantification, accuracy, inter-day precision, and intra-day precision for each PA. Overall, the method showed excellent repeatability, sensitivity, and reproducibility. The verified method was applied to tea samples, including maté, lemon balm, fennel, hibiscus, chrysanthemum, lavender, oolong tea, chamomile, rooibos, peppermint, mix tea, black, and green tea. One of the main advantages of the method developed in this study is that it allows complete separation of lycopsamine and intermedine peaks. Therefore, the method could be used to monitor PAs in teas.

Tribological behaviors of DLC films with hierarchical surface textures under water lubrication: A molecular dynamic simulation

Tribological behaviors of diamond-like carbon (DLC) films with different levels of hierarchical surface textures with lubricant water molecules are investigated through molecular dynamics simulation. The friction forces stabilize at a small value for small normal loads, due to the complete separation between DLC films by water molecules, while friction forces with large normal loads show complicated changes under the cooperation of interfacial evolution and water behaviors. Under large normal loads, friction force increases firstly due to the direct contact of surface textures which are subsequently worn and graphitized, resulting in the temporary stabilization of friction force at a large value. With their further wearing, the amount of interfacial carbon clusters decreases and water molecules distribute evenly at interface, which leads to the gradual decrease and final stabilization of friction force. During the sliding, the water molecules show a restoration in the structure and amount of hydrogen bonds, thus making these molecules play different roles in various stages, i.e., these molecules demonstrate a better diffusion during the friction rise and an enhanced separating effect for DLC films during the friction stabilization. Furthermore, the same amount of water molecules in the one-level hierarchical (L1) model has a larger bearing capacity than that in the two-level hierarchical (L2) model. When the normal load exceeds the bearing capacity of water, the friction force for model L2 is more stable and smaller than that for model L1 after running-in periods due to flattened interfaces and evenly distributed water molecules.

A FRAMEWORK FOR TRANSDISCIPLINARY RADIOCARBON RESEARCH: USE OF NATURAL-LEVEL AND ELEVATED-LEVEL 14C IN ANTARCTIC FIELD RESEARCH

ABSTRACT Radiocarbon (14C) is an isotopic tracer used to address a wide range of scientific research questions. However, contamination by elevated levels of 14C is deleterious to natural-level laboratory workspaces and accelerator mass spectrometer facilities designed to precisely measure small amounts of 14C. The risk of contaminating materials and facilities intended for natural-level 14C with elevated-level 14C-labeled materials has dictated near complete separation of research groups practicing profoundly different measurements. Such separation can hinder transdisciplinary research initiatives, especially in remote and isolated field locations where both natural-level and elevated-level radiocarbon applications may be useful. This paper outlines the successful collaboration between researchers making natural-level 14C measurements and researchers using 14C-labeled materials during a subglacial drilling project in West Antarctica (SALSA 2018–2019). Our strict operating protocol allowed us to successfully carry out 14C labeling experiments within close quarters at our remote field camp without contaminating samples of sediment and water intended for natural level 14C measurements. Here we present our collaborative protocol for maintaining natural level 14C cleanliness as a framework for future transdisciplinary radiocarbon collaborations.

A Simplified Model for Optical Systems with Random Phase Screens

A first-order optical system with arbitrary multiple masks placed at arbitrary positions is the basic scheme of various optical systems. Generally, masks in optical systems have a non-shift invariant (SI) effect; thus, the individual effect of each mask on the output cannot be entirely separated. The goal of this paper is to develop a technique where complete separation might be achieved in the common case of random phase screens (RPSs) as masks. RPSs are commonly used to model light propagation through the atmosphere or through biological tissues. We demonstrate the utility of the technique on an optical system with multiple RPSs that model random scattering media.