Hydrogen trapping and embrittlement in high-strength Al alloys.

Ever more stringent regulations on greenhouse gas emissions from transportation motivate efforts to revisit materials used for vehicles1. High-strength aluminium alloys often used in aircrafts could help reduce the weight of automobiles, but are susceptible to environmental degradation2,3. Hydrogen 'embrittlement' is often indicated as the main culprit4; however, the exact mechanisms underpinning failure are not precisely known: atomic-scale analysis of H inside an alloy remains a challenge, and this prevents deploying alloy design strategies to enhance the durability of the materials. Here we performed near-atomic-scale analysis of H trapped in second-phase particles and at grain boundaries in a high-strength 7xxx Al alloy. We used these observations to guide atomistic ab initio calculations, which show that the co-segregation of alloying elements and H favours grain boundary decohesion, and the strong partitioning of H into the second-phase particles removes solute H from the matrix, hence preventing H embrittlement. Our insights further advance the mechanistic understanding of H-assisted embrittlement in Al alloys, emphasizing the role of H traps in minimizing cracking and guiding new alloy design.

Chemical heterogeneity enhances hydrogen resistance in high-strength steels.

The antagonism between strength and resistance to hydrogen embrittlement in metallic materials is an intrinsic obstacle to the design of lightweight yet reliable structural components operated in hydrogen-containing environments. Economical and scalable microstructural solutions to this challenge must be found. Here, we introduce a counterintuitive strategy to exploit the typically undesired chemical heterogeneity within the material's microstructure that enables local enhancement of crack resistance and local hydrogen trapping. We use this approach in a manganese-containing high-strength steel and produce a high dispersion of manganese-rich zones within the microstructure. These solute-rich buffer regions allow for local micro-tuning of the phase stability, arresting hydrogen-induced microcracks and thus interrupting the percolation of hydrogen-assisted damage. This results in a superior hydrogen embrittlement resistance (better by a factor of two) without sacrificing the material's strength and ductility. The strategy of exploiting chemical heterogeneities, rather than avoiding them, broadens the horizon for microstructure engineering via advanced thermomechanical processing.

On the robustness of the Kelvin probe based potentiometric hydrogen electrode method and its application in characterizing effective hydrogen activity in metal: 5 wt. % Ni cold-rolled ferritic steel as an example.

Quantitative detection of hydrogen in metal is important in providing a better basis for fundamental investigations of hydrogen embrittlement and hydrogen-related corrosion phenomena. Thermal desorption spectroscopy (TDS) has long been used in characterizing different hydrogen traps inside materials. However, in TDS measurements, the diffusible hydrogen (hydrogen at interstitial sites and weakly bound hydrogen) is usually not detected. The Davanathan-Starchurski permeation technique can cover this shortage. However, for such experiments, the stability of the palladium at the exit side, i.e. in aqueous solution under high potential polarization is an important issue. Alternatively, a Kelvin probe-based (KP-based) potentiometric method developed a few years ago has shown to allow quantitative determination of hydrogen in metal. This method is based on measuring the hydrogen electrode potential on the Pd-coated surface. The aim of this work is to check the reliability of this method and to demonstrate its potential applications in determining the hydrogen amount distributed in both shallow and deep traps in steel. The results reveal that different crystallographic orientation, grain shapes and grain sizes of the deposited palladium film (in the range of variation in this work) do not cause relevant effects on the KP-based hydrogen detection. It is shown in this work that the time lag and permeation rate derived from the permeation curves obtained by this method show a very good reliability and the calculated hydrogen amount shows a good agreement with TDS results. 5 wt.% Ni ferritic steel is used as a model material in this work.

DR-70 (fibrinogen-fibrin degradation products) as a prognostic biomarker in dogs with neoplasms.

Fibrinogen-fibrin degradation products (DR-70) are derived from tumor cells or metastases. Our previous study reported the diagnostic values in dogs with tumors, but no research has yet to be conducted to establish DR-70 as a prognostic marker. Herein, we investigated changes in DR-70 concentrations and disease courses in dogs with tumors. Overall survival time (OST) analysis was performed in 195 dogs with tumors, stratified with a recommended cut-off (1.514 µg/mL). Continual DR-70 measurements were performed during the medical interventions of 27 dogs with neoplasms. Clinical conditions and medical records were retrospectively reviewed. According to a cut-off value, dogs with plasma DR-70 concentrations above 1.514 µg/mL had shorter survival rates than those with concentrations below this threshold. In cases with complete or partial remission in response to treatment, the DR-70 concentration was decreased compared with that at the first visit, whereas it was increased in patients with disease progression. Our study suggested that changes in DR-70 concentration can be used as a prognostic biomarker for canine neoplasms. Furthermore, increased plasma DR-70 levels might be associated with shorter survival, and DR-70 concentrations may reflect responses to medical intervention.

An evolutionarily ancient NO synthase (NOS) in shrimp.

Nitric oxide (NO) is a well known essential molecule that is involved in multiple functions such as neuron transduction, cardiac disease, immune responses, etc.; nitric oxide synthase (NOS) is a critical enzyme that catalyzes the synthesis of it. A very few crustacean NOS molecules were biochemically characterized so far. In the present study, we cloned and characterized a NOS cDNA from haemocytes of tiger shrimp (Penaeus monodon) (PmNOS). The full-length of PmNOS cDNA contained 3997 bp, including a 5'UTR of 249 bp, ORF of 3582 bp and a 3'UTR of 166 bp. The putative peptide was 1193 amino acid residues in length, with an estimated molecular weight of 134.7 kDa and pI 6.7. Structurally, PmNOS contained oxygenase and reductase domains at N-terminal and C-terminal, respectively, and connected with a calmodulin binding motif. The deduced amino acid sequence of PmNOS shared 98% identical to the Chinese shrimp (Fenneropenaeus chinensis) NOS. Phylogenetically, PmNOS clustered with invertebrate NOS, but not clustered with iNOS, eNOS or nNOS found in vertebrates. PmNOS mRNA was expressed in many tissues or organs including thoracic and ventral nerves, midgut, gill, eyestalk, haemocytes, subcuticular epithelium and heart, but not found in hepatopancreas, muscle and lymphoid organ. But there was no significant difference in PmNOS mRNA expression after stimulation with LPS either by different concentration or time course or against CpG-ODN 2006. The enzyme activities of rPmNOS or crude homogenates from different tissues were detected, and were shown its highest activity in thoracic and ventral nerves, moderate in midgut and haemocytes but the lowest activity were seen in muscle. The addition of NOS antibody against NADPH binding domain leads to less activity which suggested that NADPH was an essential cofactor for PmNOS catalytic activity. The calcium dependency of PmNOS was ascertained using calmodulin inhibitor, Trifluroperazine. To confirm the population of haemocyte which produce NOS, the florescence test was assayed, and it implicated that the production of NO was catalyzed by subset of granulocytic NOS. Since the MW range, inducible/noninducible transcript, calcium-dependent activity and tissue distribution, we suggest that PmNOS may recognize as an ancient NOS evolutionarily.

Stress analysis of glenoid component in design of reverse shoulder prosthesis using finite element method.

BACKGROUND: This study aims to clarify the effect of various designs of reverse shoulder prosthesis (RSP) on stress variation of its glenoid component using 2-dimensional (2D) finite element analysis (FEA). This FEA study provides future reference for the optimal design of glenoid component of RSP. MATERIALS AND METHODS: In this study, a 2D finite element (FE) model of human shoulder with implementation of RSP was developed by commercial FE software. The proper material properties were adopted in our model. Various design factors were simulated and all the mechanical profile data were investigated by FEA. RESULTS: Both distal placement and increased lateral offset of glenosphere induce higher stress over glenoid-baseplate junction. Increased thickness of graft, inferiorly tilting of the baseplate, and adoption of BIO-RSA (bony increased-offset reverse shoulder arthroplasty) incur higher stresses over glenoid screws. The inferior screw attains more stress than superior screw. Maximum stress occurs at the base of inferior screw. CONCLUSION: Increased eccentric offset and lateral offset of glenosphere, although being able to reduce notching, may pay the penalty of significant stress concentration over glenoid and its subsequent loosening. Maximum stress occurs at the base of inferior screw elucidate the direct contact failure mode at the middle of inferior screw. This study provides an alternative tool for the optimal design of glenoid component of RSP in the future.

Increased plasma DR-70 (fibrinogen-fibrin degradation products) concentrations as a diagnostic biomarker in dogs with neoplasms.

BACKGROUND: Tumor biomarkers have used widely in clinical oncology in human medicine. Only a few studies have evaluated the clinical utility of tumor biomarkers for veterinary medicine. A test for fibrinogen and fibrin degradation products (DR-70) has been proposed as an ideal biomarker for tumors in humans. The clinical value of DR-70 for veterinary medicine however has yet to be determined. OBJECTIVES: Investigate the diagnostic value of DR-70 concentrations by comparing them between healthy dogs and dogs with tumors. ANIMALS: Two hundred sixty-three dogs with different types of tumors were included. Sixty healthy dogs also were recruited for comparison. METHODS: The DR-70 concentrations were measured in all recruited individuals by ELISA. Clinical conditions were categorized based on histopathology, cytology, ultrasound examination, radiology, clinical findings, and a combination of these tests. RESULTS: The median concentration of DR-70 was 2.130 ± 0.868 µg/mL in dogs with tumors, which was significantly higher than in healthy dogs (1.202 ± 0.610 µg/mL; P < .0001). With a cut-off of 1.514 µg/mL, the sensitivity and specificity of DR-70 were 84.03% and 78.33%, respectively. The area under curve was 0.883. The DR-70 concentration can be an effective tumor biomarker in veterinary medicine. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased DR-70 concentrations were not affected by tumor type, sex, age, or body weight. However, in dogs with metastatic mast cell tumors and oral malignant melanoma, DR-70 concentrations were significantly increased. Additional studies, including more dogs with nonneoplastic diseases, are needed to further evaluate the usefulness of DR-70 as a tumor biomarker.

A reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals.

We demonstrate a reflective polarizer-free electro-optical switch using dye-doped polymer-stabilized blue phase liquid crystals (DDPSBP-LC). At the voltage-off state, the dye molecules and liquid crystals form the structure of the double twist cylinders. As a result, the DDPSBP-LC is in dark state due to the combination of Bragg reflection and light absorption. At the voltage-on state, the blue phase structure is unwound locally. The DDPSBP-LC is then in bright state because of the small light absorption only. The applications of such a switch are shutter glass of 3D displays, and electronic papers.

An Instrumented Glove-Controlled Portable Hand-Exoskeleton for Bilateral Hand Rehabilitation.

Effective bilateral hand training is desired in rehabilitation programs to restore hand function for people with unilateral hemiplegia, so that they can perform daily activities independently. However, owing to limited human resources, the hand function training available in current clinical settings is significantly less than the adequate amount needed to drive optimal neural reorganization. In this study, we designed a lightweight and portable hand exoskeleton with a hand-sensing glove for bilateral hand training and home-based rehabilitation. The hand-sensing glove measures the hand movement of the less-affected hand using a flex sensor. Thereafter, the affected hand is driven by the hand exoskeleton using the measured hand movements. Compared with the existing hand exoskeletons, our hand exoskeleton improves the flexible mechanism for the back of the hand for better wearing experience and the thumb mechanism to make the pinch gesture possible. We designed a virtual reality game to increase the willingness of repeated movement practice for rehabilitation. Our system not only facilitates bilateral hand training but also assists in activities of daily living. This system could be beneficial for patients with hemiplegia for starting correct and sufficient hand function training in the early stages to optimize their recovery.

Misalignment of lung vessels and alveolar capillary dysplasia: a case report with autopsy.

Misalignment of lung vessels (MLV) with or without alveolar capillary dysplasia (ACD) is a rare cause of idiopathic persistent pulmonary hypertension of the neonate. This report describes a full-term infant with severe and intractable pulmonary hypertension. The patient's condition progressively deteriorated despite high-frequency oscillatory ventilation, infusion of magnesium sulfate, dopamine, and dobutamine to control blood pressure, and nitric oxide inhalation therapy. The infant died at 5 days of age. The diagnosis of MLV with ACD was established by autopsy. Histopathologic analysis revealed a failure of formation and an ingrowth of alveolar capillaries, thickening of the alveolar walls, poor contact of capillaries with alveolar epithelium, small intra-acinar muscularized arterioles, and anomalous pulmonary veins within bronchovascular bundles. The low rate of diagnosis of MLV with or without ACD may be because of the early high mortality rate or patchy involvement in some cases. Increasing awareness of this clinical entity may prevent the use of costly, invasive, and probably ineffective procedures. Short-term improvement after inhalation of nitric oxide does not lead to long-term survival but merely provides time for potential lung transplantation.

Distribution of neuropeptide FF (NPFF) receptors in correlation with morphine-induced reward in the rat brain.

Neuropeptide FF (NPFF) exhibited anti-/pro-opioid effects when centrally injected. It was proved to bind to its own receptors, namely NPFF(1) and NPFF(2) receptors, but did not bind to opioid receptors. In our previous study, we found that i.c.v. injected NPFF suppressed morphine-induced conditioned place preference (CPP) in rats, which indicated that NPFF may play a role in the modulation of morphine-induced reward. In the present study, we further investigated the action site of NPFF to attenuate morphine-induced reward. Bilateral intra-VTA (ventral tegmental area) and intra-NAc (nucleus accumbens) injections of NPFF both blocked the CPP caused by morphine in rats. This suggests that NPFF may act at both VTA and NAc to inhibit the sensitization of the mesocorticolimbic dopaminergic pathway. Neurochemical analyses support that NPFF could be acting through the inhibition of the mesocorticolimbic dopaminergic activity increased by morphine. We also determined the distribution of NPFF receptors in rat brains. Our results showed that both NPFF receptors were abundantly expressed in VTA but with less content in NAc. In fluorescent immunohistochemical staining, our results revealed that NPFF(1) and NPFF(2) receptors could be expressed at the TH (tyrosine hydroxylase)- or GAD67 (glutamic acid decarboxylase-67)-positive neurons in VTA, whereas some of them were present in the negative neurons. This implied a possible function of NPFF to modulate dopaminergic neurons directly and a possible indirect action of NPFF on GABAergic neurons to modulate dopamine release. Taken together, our study should be helpful for clarifying the possible mechanisms of NPFF system to modulate morphine-induced reward.