Effect of Cr and N on the Stress Corrosion Cracking Behavior of Fe-18Mn Steel

High-Mn steels developed for offshore industries require good resistance to stress corrosion cracking (SCC) in seawater. Elements like Cr and N are often added to improve the resistance to SCC. In this study, the SCC behavior of Fe18Mn3Cr0.1N and Fe19Mn19Cr0.6N steels in artificial seawater was examined. Slow strain rate tests were conducted at a nominal strain rate of 10(-6)/sec in air and artificial seawater under anodic and cathodic applied potentials. The tensile ductility drop in artificial seawater was compared to air and evaluated as the resistance to SCC. It was found that both specimens showed intergranular cracking in artificial seawater under both anodic and cathodic applied potentials. The intergranular SCC was more severe under anodic applied potential than cathodic applied potential. However the sensitivity to SCC in artificial seawater was substantially reduced in Fe19Mn19Cr0.6N specimen with higher Cr and N content, as compared to the Fe18Mn3Cr0.1N specimen under both applied potentials. Potentiodynamic tests in artificial seawater showed an increase in pitting corrosion potential, rather than corrosion potential, with increasing Cr and N content in high-Mn steel. The SCC behavior of high-Mn steels with different Cr and N contents was discussed based on micrographic and fractographic observations.11Ysciescopuskc

The tarantula toxin GxTx detains K+ channel gating charges in their resting conformation.

Allosteric ligands modulate protein activity by altering the energy landscape of conformational space in ligand-protein complexes. Here we investigate how ligand binding to a K+ channel's voltage sensor allosterically modulates opening of its K+-conductive pore. The tarantula venom peptide guangxitoxin-1E (GxTx) binds to the voltage sensors of the rat voltage-gated K+ (Kv) channel Kv2.1 and acts as a partial inverse agonist. When bound to GxTx, Kv2.1 activates more slowly, deactivates more rapidly, and requires more positive voltage to reach the same K+-conductance as the unbound channel. Further, activation kinetics are more sigmoidal, indicating that multiple conformational changes coupled to opening are modulated. Single-channel current amplitudes reveal that each channel opens to full conductance when GxTx is bound. Inhibition of Kv2.1 channels by GxTx results from decreased open probability due to increased occurrence of long-lived closed states; the time constant of the final pore opening step itself is not impacted by GxTx. When intracellular potential is less than 0 mV, GxTx traps the gating charges on Kv2.1's voltage sensors in their most intracellular position. Gating charges translocate at positive voltages, however, indicating that GxTx stabilizes the most intracellular conformation of the voltage sensors (their resting conformation). Kinetic modeling suggests a modulatory mechanism: GxTx reduces the probability of voltage sensors activating, giving the pore opening step less frequent opportunities to occur. This mechanism results in K+-conductance activation kinetics that are voltage-dependent, even if pore opening (the rate-limiting step) has no inherent voltage dependence. We conclude that GxTx stabilizes voltage sensors in a resting conformation, and inhibits K+ currents by limiting opportunities for the channel pore to open, but has little, if any, direct effect on the microscopic kinetics of pore opening. The impact of GxTx on channel gating suggests that Kv2.1's pore opening step does not involve movement of its voltage sensors

A 1.35GHz All-Digital Fractional-N PLL with Adaptive Loop Gain Controller and Fractional Divider

A 1.35GHz all-digital phase-locked loop (ADPLL) with an adaptively controlled loop filter and a 1/3rd-resolution fractional divider is presented. The adaptive loop gain controller (ALGC) effectively reduces the nonlinear characteristics of the bang-bang phase-frequency detector (BBPFD). The fractional divider partially compensates for the input phase error which is caused by the fractional-N frequency synthesis operation. A prototype ADPLL using a BBPFD with a dead zone free retimer, an ALGC, and a fractional divider is fabricated in 0.13m CMOS. The core occupies 0.19mm2 and consumes 13.7mW from a 1.2V supply. The measured RMS jitter was 4.17ps at a 1.35GHz clock output

Understanding the catalytic chemisorption of the cyanogen chloride via breakthrough curve and genetic algorithm

This study investigated the catalytic chemisorption of cyanogen chloride(CK) with a metal(ASZM) – triethylenediamine(TEDA) complex. XPS data, IR spectra, and DFT calculations demonstrated that the synergetic catalytic hydrolysis of CK by ASZM-TEDA is kinetically favorable, with the enhanced reactivity of water on the catalyst as the primary cause for the accelerated catalytic hydrolysis. To validate the results, ASZM-TEDA was impregnated into activated carbon beads to form a packed-bed reactor for this breakthrough experiment. The proposed species-transport equation parameters were fitted using the genetic algorithm, and the correlation between parameters was compared. The study concludes that TEDA can affect the diffusivity for overall mass transfer-related reactions and accelerate the catalytic reaction of metal with CK. This study is the first to describe chemisorbed breakthrough with catalyst reaction in-depth and provides insights into the optimized ratio between TEDA and metal complexes. This methodology can be applied to various breakthrough experiments with chemical reactions

Longitudinal cephalometric study of untreated subjects with different facial types

To examine the craniofacial morphological characteristics of different facial types based on vertical dysplasia in untreated subjects from the ages of 8 to 18

Evaluation of Skeletal and Dental Asymmetries in Patients with Angle Class II Subdivision Malocclusion with 3-Dimensional Analysis of Cone-Beam Computed Tomography

• Dentofacial asymmetries can present substantial challenges to orthodontic treatment.1 They, which can be congenital, developmental, and acquired, are based on discrepancies in the two halves of the face with reference to size, form, and arrangement of facial landmarks. • Class II subdivision malocclusions show more than half-step Class II occlusion on one side of the dental arch and Class I molar occlusion on the other side of the dental arch. They attribute to 50% of all Class II malocclusions and are one of the most frequent dental asymmetries in the orthodontic population.2 • Cone-beam computed tomography (CBCT) can be used to examine skeletal and dental asymmetries in Class II subdivision malocclusions and other morphological features of the craniofacial structures of facial asymmetry.3 • Mandibular asymmetry (skeletal) was the primary factor that contributed to Angle Class II subdivision malocclusions. Class II side had shorter total mandibular length and ramus height and deviated mandibular dental midline landmarks (pogonion and menton). Mandibular dental landmarks were positioned more latero-posterio-superiorly.

Onychomycosis Caused by Scopulariopsis brevicaulis: Report of Two Cases

Onychomycosis is usually caused by dermatophytes, but some nondermatophytic molds and yeasts are also associated with invasion of nails. Scopulariopsis brevicaulis is a nondermatophytic mold found in soil as a saprophyte. We report two cases of onychomycosis caused by S. brevicaulis in a 48-year-old male and a 79-year-old female. The two patients presented with a typical distal and lateral subungual onychomycosis. Direct microscopic examination of the potassium hydroxide preparation revealed fungal elements. From toenail lesions of the patients, brown colonies with powdery surface, which are a characteristic of S. brevicaulis, were cultured on two Sabouraud's dextrose agar plates. Three cultures taken from nail plates within a 2-week interval yielded similar findings. Numerous branched conidiophores with chains of rough walled, lemon-shaped conidia were observed in slide culture by light microscopy and scanning electron microscopy. The nucleotide sequences of the internal transcribed spacer for the two clinical isolates were identical to that of S. brevicaulis strain WM 04.498. To date, a total of 13 cases of S. brevicaulis onychomycosis including the two present cases have been reported in Korea. Mean age of the patients was 46.1 years, with a higher prevalence in males (69.2%). Toenail involvement was observed in all cases including a case involving both fingernail and toenail. The most frequent clinical presentation was distal and lateral subungual onychomycosis in 12 cases, while one case was proximal subungual onychomycosis