Influence of Fluorocarbon and Hydrocarbon Acyl Groups at the Surface of Bovine Carbonic Anhydrase II on the Kinetics of Denaturation by Sodium Dodecyl Sulfate

This paper examines the influence of acylation of the Lys-ε-NH3+ groups of bovine carbonic anhydrase (BCA, EC 4.2.1.1) to Lys-ε-NHCOR (R = −CH3, −CH2CH3, and −CH(CH3)2, −CF3) on the rate of denaturation of this protein in buffer containing sodium dodecyl sulfate (SDS). Analysis of the rates suggested separate effects due to electrostatic charge and hydrophobic interactions. Rates of denaturation (kAc,n) of each series of acylated derivatives depended on the number of acylations (n). Plots of log kAc,n vs n followed U-shaped curves. Within each series of derivatives, rates of denaturation decreased as n increased to 7; this decrease was compatible with increasingly unfavorable electrostatic interactions between SDS and protein. In this range of n, rates of denaturation also depended on the choice of the acyl group as n increased to 7, in a manner compatible with favorable hydrophobic interactions between SDS and the −NHCOR groups. As n increased in the range 7 < n < 14, however, rates of denaturation stayed approximately constant; analysis suggested that these rates were compatible with an increasingly important contribution to denaturation that depended both on the net negative charge of the protein and on the hydrophobicity of the R group. The mechanism of denaturation thus seems to change with the extent of acylation of the protein. For derivatives with the same net electrostatic charge, rates of denaturation increased with the acyl group (by a factor of 3 for n 14) in the order CH3CONH− < CH3CH2CONH− < (CH3)2CHCONH− < CF3CONH−. These results suggested that the hydrophobicity of CF3CONH− is slightly greater (by a factor of <2) than that of RHCONH− with similar surface area.Chemistry and Chemical Biolog

Templated Self-Assembly in Three Dimensions Using Magnetic Levitation

Although self-assembly (SA) in two dimensions (2D) is highly developed (especially using surfaces as a templates), SA in three dimensions (3D) has been more difficult. This paper describes a strategy for SA in 3D of diamagnetic plastic objects (mm- to cm-sized in this work, but in principle in sizes from [similar]10 μm to m) supported in a paramagnetic fluid by a non-uniform magnetic field. The magnetic field and its gradient levitate the objects, template their self-assembly, and influence the shape of the assembled cluster. The structure of the 3D assembling objects can be further directed using hard mechanical templates—either the walls of the container or co-levitating components—which coincide spatially with the soft template of the magnetic field gradient. Mechanical agitation anneals the levitating clusters; the addition of photocurable adhesive, followed by UV illumination, can permanently fuse components together.Chemistry and Chemical Biolog

Paramagnetic Ionic Liquids for Measurements of Density Using Magnetic Levitation

Paramagnetic ionic liquids (PILs) provide new capabilities to measurements of density using magnetic levitation (MagLev). In a typical measurement, a diamagnetic object of unknown density is placed in a container containing a PIL. The container is placed between two magnets (typically NdFeB, oriented with like poles facing). The density of the diamagnetic object can be determined by measuring its position in the magnetic field along the vertical axis (levitation height, h), either as an absolute value, or relative to internal standards of known density. For density measurements by MagLev, PILs have three advantages over solutions of paramagnetic salts in aqueous or organic solutions: (i) negligible vapor pressures; (ii) low melting points; (iii) high thermal stabilities. In addition, the densities, magnetic susceptibilities, glass transition temperatures, thermal decomposition temperatures, viscosities, and hydrophobicities of PILs can be tuned over broad ranges by choosing the cation–anion pair. The low melting points and high thermal stabilities of PILs provide large liquidus windows for density measurements. This paper demonstrates applications and advantages of PILs in density-based analyses using MagLev.Chemistry and Chemical Biolog

Cooperation and achievement in preschoolers

According to recent research, children’s learning related skills, such as cooperation, self-regulation, responsibility, and independence, are closely related to their academic outcomes (McClelland, Acock, Morrison 2006). While self regulation during preschool and it’s related skills are predictors of later academic achievement, it might be beneficial to determine a simple screening tool that would identify children who might need to be assessed more in-depth to determine if they would benefit from interventions. Specifically, cooperation with peers is an easily observable behavior, and a predictor of achievement (Ladd, Birtch, and Buhs, 1999), which can be measured with the Observed Child Engagement Scale (Rimm-Kaufman, Curby, Grimm, Nathanson, and Brock, 2009). Scores for preschoolers’ peer cooperation in on the OCES have been found to be related to scores on a self-regulation measure, the Head Toes Knees Shoulders (HTKS) task. Additionally, performance on the HTKS task can be predictive of later academic performance (Ponitz, McClelland, Matthews, and Morrison, 2009). Given the close nature of these relationships, it might be beneficial to further explore the connections between cooperation and achievement. This study attempts to determine those connections by exploring the relationship between observed instances of cooperation with peers as scored on the OCES and academic achievement scores on the Woodcock-Johnson Psychoeducational Battery III Tests of Achievement Applied Problems and Letter-Word Identification subscales (Woodcock and Mather, 2000). The study investigates the following question: (1) What is the relationship between instances of observed cooperation with peers on the OCES and scores Woodcock-Johnson III achievement tasks

Measuring Markers of Liver Function Using a Micropatterned Paper Device Designed for Blood from a Fingerstick

This paper describes a paper-based microfluidic device that measures two enzymatic markers of liver function (alkaline phosphatase, ALP, and aspartate aminotransferase, AST) and total serum protein. A device consists of four components: (i) a top plastic sheet, (ii) a filter membrane, (iii) a patterned paper chip containing the reagents necessary for analysis, and (iv) a bottom plastic sheet. The device performs both the sample preparation (separating blood plasma from erythrocytes) and the assays; it also enables both qualitative and quantitative analysis of data. The data obtained from the paper-microfluidic devices show standard deviations in calibration runs and “spiked” standards that are acceptable for routine clinical use. This device illustrates a type of test useable for a range of assays in resource-poor settings.Chemistry and Chemical Biolog

Fluoroalkyl and Alkyl Chains Have Similar Hydrophobicities in Binding to the “Hydrophobic Wall” of Carbonic Anhydrase

This paper describes the performance of junctions based on self-assembled monolayers (SAMs) as the functional element of a half-wave rectifier (a simple circuit that converts, or rectifies, an alternating current (AC) signal to a direct current (DC) signal). Junctions with SAMs of 11-(ferrocenyl)-1-undecanethiol or 11-(biferrocenyl)-1-undecanethiol on ultraflat, template-stripped Ag (AgTS) bottom electrodes, and contacted by top electrodes of eutectic indium–gallium (EGaIn), rectified AC signals, while similar junctions based on SAMs of 1-undecanethiol—SAMs lacking the ferrocenyl terminal group—did not. SAMs in these AC circuits (operating at 50 Hz) remain stable over a larger window of applied bias than in DC circuits. AC measurements, therefore, can investigate charge transport in SAM-based junctions at magnitudes of bias inaccessible to DC measurements. For junctions with SAMs of alkanethiols, combining the results from AC and DC measurements identifies two regimes of bias with different mechanisms of charge transport: (i) low bias (|V| 1.3 V), at which Fowler–Nordheim (FN) tunneling dominates. For junctions with SAMs terminated by Fc moieties, the transition to FN tunneling occurs at |V| ≈ 2.0 V. Furthermore, at sufficient forward bias (V > 0.5 V), hopping makes a significant contribution to charge transport and occurs in series with direct tunneling (V 2.0 V) until FN tunneling activates (V 2.0 V). Thus, for Fc-terminated SAMs at forward bias, three regimes are apparent: (i) direct tunneling (V = 0–0.5 V), (ii) hopping plus direct tunneling (V ≈ 0.5–2.0 V), and (iii) FN tunneling (V 2.0 V). Since hopping does not occur at reverse bias, only two regimes are present over the measured range of reverse bias. This difference in the mechanisms of charge transport at forward and reverse bias for junctions with Fc moieties resulted in large rectification ratios (R > 100) and enabled half-wave rectification.Chemistry and Chemical Biolog

Using Magnetic Levitation to Separate Mixtures of Crystal Polymorphs

Magnetische Levitation (MagLev) ist eine einfache Trennmethode für Kristallpolymorphe mit Dichteunterschieden (Δρ) von nur 0.001 g cm−3. Für vier organische Verbindungen wurden dichtebasierte Trennungen verschiedener kristalliner Formen gezeigt: 5-Methyl-2-[(2-nitrophenyl)amino]-3-thiophencarbonitril, Sulfathiazol, Carbamazepin und trans-Zimtsäure.Chemistry and Chemical Biolog

Reviews and syntheses: The promise of big diverse soil data, moving current practices towards future potential

In the age of big data, soil data are more available and richer than ever, but – outside of a few large soil survey resources – they remain largely unusable for informing soil management and understanding Earth system processes beyond the original study. Data science has promised a fully reusable research pipeline where data from past studies are used to contextualize new findings and reanalyzed for new insight. Yet synthesis projects encounter challenges at all steps of the data reuse pipeline, including unavailable data, labor-intensive transcription of datasets, incomplete metadata, and a lack of communication between collaborators. Here, using insights from a diversity of soil, data, and climate scientists, we summarize current practices in soil data synthesis across all stages of database creation: availability, input, harmonization, curation, and publication. We then suggest new soil-focused semantic tools to improve existing data pipelines, such as ontologies, vocabulary lists, and community practices. Our goal is to provide the soil data community with an overview of current practices in soil data and where we need to go to fully leverage big data to solve soil problems in the next century

Risk and protective genetic variants in suicidal behaviour: association with SLC1A2, SLC1A3, 5-HTR1B &NTRK2 polymorphisms

<p>Abstract</p> <p>Background</p> <p>Suicidal behaviour is known to aggregate in families. Patients with psychiatric disorders are at higher risk for suicide attempts (SA), however protective and risk genetic variants for suicide appear to be independent of underlying psychiatric disorders. Here we investigate genetic variants in genes important for neurobiological pathways linked to suicidal behaviour and/or associated endophenotypes, for association with SA among patients with co-existing psychiatric illness. Selected gene-gene and gene-environment interactions were also tested.</p> <p>Methods</p> <p>DNA was obtained from bloods of 159 patients (76 suicide attempters and 83 non-attempters), who were profiled for DSM-IV Axis I psychiatric diagnosis. Twenty-eight single nucleotide polymorphisms (SNPs) from 18 candidate genes (<it>COMT, 5-HT2A, 5-HT1A, 5-HTR1B, TPH1, MAO-A, TPH2, DBH, CNR1, BDNF, ABCG1, GABRA5, GABRG2, GABRB2, SLC1A2, SLC1A3, NTRK2, CRHR1</it>) were genotyped. Genotyping was performed by KBioscience. Tests of association between genetic variants and SA were conducted using Chi squared and Armitage Trend tests. Binary logistical regression analyses were performed to evaluate the contribution of individual genetic variants to the prediction of SA, and to examine SNPs for potential gene-gene and gene-environment interactions.</p> <p>Results</p> <p>Our analysis identified 4 SNPs (rs4755404, rs2269272, rs6296 and rs1659400), which showed evidence of association with SA compared to a non-attempter control group. We provide evidence of a 3-locus gene-gene interaction, and a putative gene-environment interaction, whereby genetic variation at the <it>NTRK2 </it>locus may moderate the risk associated with history of childhood abuse.</p> <p>Conclusion</p> <p>Preliminary findings suggest that allelic variability in <it>SLC1A2/3, 5-HTR1B </it>and <it>NTRK2 </it>may be relevant to the underlying diathesis for suicidal acts.</p