Pulsed Electrolysis with a Nickel Molecular Catalyst Improves Selectivity for Carbon Dioxide Reduction

Pulsed electrolysis can significantly improve carbon dioxide reduction on metal electrodes, but the effect of short (millisecond to seconds) voltage steps on molecular electrocatalysts is largely unstudied. In this work, we investigate the effect pulse electrolysis has on the selectivity and stability of the homogeneous electrocatalyst [Ni(cyclam)]²⁺ at a carbon electrode. By tuning the potential and pulse duration, we achieve a significant improvement in CO Faradaic efficiencies (85%) after 3 h, double that of the system under potentiostatic conditions. The improved activity is due to in situ catalyst regeneration from an intermediate that occurs as part of the catalyst's degradation pathway. This study demonstrates the wider opportunity to apply pulsed electrolysis to molecular electrocatalysts to control activity and improve selectivity.

Zero-Gap Bipolar Membrane Electrolyzer for Carbon Dioxide Reduction Using Acid-Tolerant Molecular Electrocatalysts

The scaling-up of electrochemical CO₂ reduction requires circumventing the CO₂ loss as carbonates under alkaline conditions. Zero-gap cell configurations with a reverse-bias bipolar membrane (BPM) represent a possible solution, but the catalyst layer in direct contact with the acidic environment of a BPM usually leads to H₂ evolution dominating. Here we show that using acid-tolerant Ni molecular electrocatalysts selective (>60%) CO₂ reduction can be achieved in a zero-gap BPM device using a pure water and CO₂ feed. At a higher current density (100 mA cm^-2), CO selectivity decreases, but was still >30%, due to reversible product inhibition. This study demonstrates the importance of developing acid-tolerant catalysts for use in large-scale CO₂ reduction devices.

No re-calibration required? Stability of a bioelectrochemical sensor for biodegradable organic matter over 800 days

Microbial Fuel Cells (MFCs) operated as biosensors could potentially enable truly low-cost, real-time monitoring of organic loading in wastewaters. The current generated by MFCs has been correlated with conventional measures of organic load such as Biochemical Oxygen Demand (BOD), but much remains to be established in terms of the reliability and applicability of such sensors. In this study, batch-mode and multi-stage, flow-mode MFCs were operated for over 800 days and regularly re-calibrated with synthetic wastewater containing glucose and glutamic acid (GGA). BOD5 calibration curves were obtained by normalising the current measured as a percentage of maximum current. There was little drift between recalibrations and non-linear Hill models of the combined dataset had R2 of 88-95%, exhibiting a stable response over time and across devices. Nonetheless, factors which do affect calibration were also assessed. Increasing external resistance (from 43.5 to 5100 Ω) above the internal resistance determined by polarisation curve decreased the calibration upper limit from 240 to 30 mg/l O2 BOD5. Furthermore, more fermentable carbon sources increased the detection range, as tested with samples of real wastewater and synthetic media containing GGA, glucose-only and glutamic acid-only. Biofilm acclimatisation therefore did not account for differences between aerobic oxygen demand determinations and anaerobic MFC responses; these are likely attributable to competitive processes such as fermentation. This further highlights the potential for MFCs as real-time sensors for organic load monitoring and process control in addition to BOD-compliant measurement systems.

Enhanced bio-production from CO2 by microbial electrosynthesis (MES) with continuous operational mode

Technologies able to convert CO2 to various feedstocks for fuels and chemicals are emerging due to the urge of reducing greenhouse gas emissions and de-fossilizing chemical production. Microbial electrosynthesis (MES) has been shown a promising technique to synthesize organic products particularly acetate using microorganisms and electrons. However, the efficiency of the system is low. In this study, we demonstrated the simple yet efficient strategy in enhancing the efficiency of MES by applying continuous feeding regime. Compared to the fed-batch system, continuous operational mode provided better control of pH and constant medium refreshment, resulting in higher acetate production rate and more diverse bio-products, when the cathodic potential of -1.0 V Ag/AgCl and dissolved CO2 were provided. It was observed that hydraulic retention time (HRT) had a direct effect on the pattern of production, acetate production rate and coulombic efficiency. At HRT of 3 days, pH was around 5.2 and acetate was the dominant product with the highest production rate of 651.8 ± 214.2 ppm per day and a significant coulombic efficiency of 90%. However at the HRT of 7 days, pH was lower at around 4.5, and lower but stable acetate production rate of 280 ppm per day and a maximum coulombic efficiency of 80% was obtained. In addition, more diverse and longer chain products, such as butyrate, isovalerate and caproate, were detected with low concentrations only at the HRT of 7 days. Although microbial community analysis showed the change in the planktonic cells communities after switching the fed-batch mode to continuous feeding regime, Acetobacterium still remained as the responsible bacteria for CO2 reduction to acetate, dominating the cathodic biofilm.

Copper-Indium Binary Catalyst on a Gas Diffusion Electrode for High-Performance CO2 Electrochemical Reduction with Record CO Production Efficiency

Cu-In metallic hybrid is a promising non-noble catalyst for selective electrochemical CO₂ reduction (eCO₂R) to CO, but the lack of direct assembly with a gas diffusion electrode (GDE) limits the further development of eCO₂R to CO with both high Faradaic efficiency (FE) and high current density. In this study, an in situ electrochemical spontaneous precipitation (ESP) method was applied for the first time to prepare GDE-combined Cu-In electrocatalysts. The optimum Cu-In catalyst consists of a nanoscale "core-shell" structure of polycrystalline Cu_xO covered by the amorphous In(OH)₃ interface. Higher than 90% FE of CO production has been achieved. With the synergy of a GDE flow cell and 1 M KOH catholyte, a current density of ∼200 mA cm^-2 was reached at -1.17 V (reversible hydrogen electrode), which enabled a CO yield efficiency record of 3.05 mg min^-1(CO₂/15 mL min^-1 with a 2 cm² electrode). The ratios between CO and H₂ produced can be effectively modulated via fine-tuning ESP conditions demonstrating possibility of generating CO or syngas with tuneable ratios. The present study provides a simple approach for constructing novel catalytic interfaces with dual active centers for eCO₂R and other emerging electrochemical catalysis research.

Bioelectrochemical treatment and recovery of copper from distillery waste effluents using power and voltage control strategies

Copper recovery from distillery effluent was studied in a scalable bioelectro-chemical system with approx. 6.8 L total volume. Two control strategies based on the control of power with maximum power point tracking (MPPT) and the application of 0.5 V using an external power supply were used to investigate the resultant modified electroplating characteristics. The reactor system was constructed from two electrically separated, but hydraulically connected cells, to which the MPPT and 0.5 V control strategies were applied. Three experiments were carried out using a relatively high copper concentration i.e. 1000 mg/L followed by a lower concentration i.e. 50 mg/L, with operational run times defined to meet the treatment requirements for distillery effluents considered. Real distillery waste was introduced into the cathode to reduce ionic copper concentrations. This waste was then recirculated to the anode as a feed stock after the copper depletion step, in order to test the bioenergy self-sustainability of the system. Approx. 60-95% copper was recovered in the form of deposits depending on starting concentration. However, the recovery was low when the anode was supplied with copper depleted distillery waste. Through process control (MPPT or 0.5 V applied voltage) the amount and form of the copper recovered could be manipulated.

Family history and APOE4 risk for Alzheimer's disease impact the neural correlates of episodic memory by early midlife

Episodic memory impairment is a consistent, pronounced deficit in pre-clinical stages of late-onset Alzheimer's disease (AD). Individuals with risk factors for AD exhibit altered brain function several decades prior to the onset of AD-related symptoms. In the current event-related fMRI study of spatial context memory we tested the hypothesis that middle-aged adults (MA; 40–58 yrs) with a family history of late onset AD (MA_+ FH), or a combined + FH and apolipoprotein E ε4 allele risk factors for AD (MA_{+ FH + APOE4}), will exhibit differences in encoding and retrieval-related brain activity, compared to − FH − APOE4 MA controls. We also hypothesized that the two at-risk MA groups will exhibit distinct patterns of correlation between brain activity and memory performance, compared to controls. To test these hypotheses we conducted multivariate task, and behavior, partial least squares analysis of fMRI data obtained during successful context encoding and retrieval. Our results indicate that even though there were no significant group differences in context memory performance, there were significant differences in brain activity and brain-behavior correlations involving the hippocampus, inferior parietal cortex, cingulate, and precuneus cortex in MA with AD risk factors, compared to controls. In addition, we observed that brain activity and brain-behavior correlations in anterior-medial PFC and in ventral visual cortex differentiated the two MA risk groups from each other, and from MA_controls. Our results indicate that functional differences in episodic memory-related regions are present by early midlife in adults with + FH and + APOE-4 risk factors for late onset AD, compared to middle-aged controls.

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FMRI study of context memory in middle-aged adults (MA) with vs. without specific AD risk factors

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MA with vs. without AD risk factors show different angular gyrus, cingulate and precuneus activity patterns.

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MA with AD risk factors showed increased hippocampus activity at encoding, compared to controls.

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Medial PFC and visual cortex function differentiated + FH vs. + APOE4 MA risk groups.

Oral carcinoma with perineural invasion has higher nerve growth factor expression and worse prognosis

BACKGROUND

This study elucidated the association between histopathological factors and the prognosis of oral carcinoma. As the histopathological factors were determined from the surgical specimen and this can only be used for the choices of postoperative regimens, this study also investigated the linkage between prognostic factors and the expression of key molecules to examine the feasibility of markers as predictors.

METHODS

Clinicopathological factors of 101 oral carcinomas were cross-analyzed with disease-free survival. The expression of nerve growth factor (NGF) and its receptor, tyrosine kinase A receptor, was assayed with immunohistochemistry.

RESULTS

Nodal metastasis was the most crucial clinical predictor for disease-free survival. Perineural invasion (PNI) was an independent histopathological predictor for both nodal metastasis (P = 0.004) and disease-free survival (P = 0.019). Patients with advanced tumor and PNI exhibited the high hazard for tumor progression and poor disease-free survival. NGF immunoreactivity in tumors was correlated with PNI (P = 0.005) and neck lymph node metastasis (P = 0.036).

CONCLUSION

Perineural invasion is the indicator of worst prognosis. As NGF immunoreactivity was found to be associated with PNI and nodal metastasis, the NGF immunoreactivity of oral carcinoma revealed by diagnostic biopsy suggests that alternative therapeutic approaches might be appropriate.

Metformin increases insulin sensitivity and plasma beta-endorphin in human subjects

Metformin has been widely used in clinical type 2 diabetes treatment and prevention. The present study was designed to explore the effect on people with a sedentary lifestyle at therapeutic doses. Twenty-two physically-inactive volunteers with normal glucose tolerance were studied. Escalating doses of metformin in low-dose (250 mg), intermediate-dose (500 mg), and high-dose (750 mg) treatment three times per day were administrated into each subject for a three-week treatment period. Fasting plasma glucose, A1C, HOMA-IR for insulin resistance, lipid profile, and plasma beta-endorphin-like immunoreactivity (BER) were measured before treatment and weekly at the end of each dosing period. Metformin significantly reduced fasting plasma glucose and HOMA-IR in healthy humans after receiving this treatment at therapeutic doses including low-dose (5 %, 17 %), intermediate-dose (6 %, 25 %) and high-dose treatment (6 %, 21 %). Plasma BER was also increased from 135.46 +/- 61.73 pg/ml to 137.52 +/- 66.11 pg/ml by low-dosing (p = 0.39), to 139.17 +/- 64.08 pg/ml by intermediate-dosing (p = 0.32), and to 149.59 +/- 63.32 pg/ml by high-dosing (p < 0.05). Also, serum cholesterol decreased significantly using metformin at therapeutic doses including low-dose (4 %), intermediate-dose (8 %) and high-dose treatment (7 %). However, metformin failed to modify levels of serum HDL-cholesterol and C-reactive protein (CRP) in healthy subjects. Also, the reduction of serum cholesterol by metformin did not correlate to the increase in insulin sensitivity. In conclusion, metformin causes a significant parallel increase in insulin sensitivity and plasma beta-endorphin level in human subjects.

Cytochrome c Release and Caspase-3 Activation in Retinal Ganglion Cells Following Different Distance of Axotomy of the Optic Nerve in Adult Hamsters

This study examined the relationship between the distance of axotomy and the death of injured retinal ganglion cells (RGCs) in adult hamsters and the relationship of cytochrome c and caspase-3 on the death pathway of RGCs. The left optic nerve (ON) of adult hamsters was transected either at 1 or 3 mm away from the optic disc, and retrogradely labeled with Flurogold on the ON stump. After a predetermined period of postoperative time, the surviving RGCs were counted by retina flat-mount, and the activation of cytochrome c and caspase-3 were investigated by immunohistochemistry. Cell loss was found to be much faster (P < 0.01), more cells with cytochrome c were observed (P < 0.05) and the activation of caspase-3 was earlier when ON was transected 1 mm away from the optic disc than when was transected 3 mm away from the optic disc. Distance of axotomy affects the axotomized cell death rate where more RGCs died when the ON transection was applied closer to the eye. The timing of activation of caspase-3 in the RGCs may be linked to the distance of axotomy.

Contrast-enhanced quantitation of left ventricular ejection fraction: what is the best method?

The need to enhance the echocardiographic determination of left ventricular ejection fraction (LVEF) is greatest in patients with suboptimal images. We have previously demonstrated that in difficult-to-image patients, contrast-enhanced power harmonic imaging resulted in accurate calculation of LVEF by using Simpson's method. However, the incremental accuracy of contrast enhancement with other methods of determining LVEF has not been examined. This study prospectively assessed the comparative accuracy of LVEF determination by using the Quinones' method with fundamental imaging (FU), tissue harmonic imaging (TH), contrast-enhanced harmonic imaging [TH(CON)], as well as Quinones' method with contrast-enhanced power harmonic imaging [POW(QUIN)] in 62 patients with suboptimal images. LVEF was also calculated by using contrast-enhanced power harmonic imaging and Simpson's method [POW(SIMP)] in these patients. We demonstrated that LVEF calculated from the POW(QUIN) mode had the best agreement with radionuclide angiography (standard of comparison) compared with FU, TH, and TH(CON). However, POW(SIMP) was even more accurate. In conclusion, when the Quinones' method was used to calculate LVEF in difficult-to-image patients, POW(QUIN) mode was the most accurate. However, POW(SIMP) was even more accurate and should be the method of choice when a high degree of quantitative accuracy is required.

A Rho-dependent signaling pathway operating through myosin localizes beta-actin mRNA in fibroblasts

BACKGROUND

The sorting of mRNA is a determinant of cell asymmetry. The cellular signals that direct specific RNA sequences to a particular cellular compartment are unknown. In fibroblasts, beta-actin mRNA has been shown to be localized toward the leading edge, where it plays a role in cell motility and asymmetry.

RESULTS

We demonstrate that a signaling pathway initiated by extracellular receptors acting through Rho GTPase and Rho-kinase regulates this spatial aspect of gene expression in fibroblasts by localizing beta-actin mRNA via actomyosin interactions. Consistent with the role of Rho as an activator of myosin, we found that inhibition of myosin ATPase, myosin light chain kinase (MLCK), and the knockout of myosin II-B in mouse embryonic fibroblasts all inhibited beta-actin mRNA from localizing in response to growth factors.

CONCLUSIONS

We therefore conclude that the sorting of beta-actin mRNA in fibroblasts requires a Rho mediated pathway operating through a myosin II-B-dependent step and postulate that polarized actin bundles direct the mRNA to the leading edge of the cell.

Mitral regurgitation in hypertrophic obstructive cardiomyopathy: relationship to obstruction and relief with myectomy

OBJECTIVES

This study examined: 1) the impact of myectomy on postoperative mitral regurgitation (MR) and 2) the association between the severity of MR and the left ventricular outflow tract (LVOT) gradient.

BACKGROUND

For patients with hypertrophic obstructive cardiomyopathy (HOCM) and MR, controversy exists as to whether myectomy alone is sufficient in eliminating MR. Furthermore, the relationship between the degree of MR and the LVOT peak gradient has not been well defined.

METHODS

We performed pre- and postoperative transthoracic as well as intraoperative transesophageal studies in 104 consecutive patients with HOCM undergoing septal myectomy. Left ventricular outflow tract gradient and the nature of MR were assessed.

RESULTS

In the 93 patients without independent mitral valve disease, a relationship was observed between MR severity and the LVOT gradient. Left ventricular outflow tract gradient (mean +/- standard deviation) for trivial, mild, moderate and severe MR were: 23.2+/-19.1, 43.8+/-25.4, 70.1+/-21.0 and 104+/-21.0 mm Hg (p < 0.001). Early postoperative, MR was absent or trivial in 80%, mild in 19% and moderate in 1%. None of these patients required additional mitral valve surgery. For patients with independent mitral valve disease (n = 11), five required mitral valve surgery as well as myectomy. The remainder had significant reductions in the degree of MR with myectomy alone.

CONCLUSIONS

For patients with HOCM and MR not due to independent mitral valve disease, myectomy significantly reduced the degree of MR, without requirement for additional mitral valve surgery. In these patients the severity of MR was directly related to the magnitude of the LVOT gradient.

Feasibility and accuracy of left ventricular volumes and ejection fraction determination by fundamental, tissue harmonic, and intravenous contrast imaging in difficult-to-image patients

The need to enhance the echocardiographic determination of left ventricular ejection fraction is greatest in patients with suboptimal images. Intravenous contrast (CON) and tissue harmonic imaging (THI) are 2 important methods for enhancing endocardial border definition. However, the comparative feasibility and accuracy of THI and contrast-enhanced power harmonic imaging in difficult-to-image patients have not been examined. We assessed the comparative accuracy of THI and CON in determining EF and ventricular volumes in patients with suboptimal fundamental images. We demonstrated that CON is feasible and exhibits a greater correlation with ejection fraction and ventricular volumes determined by radionuclide angiography (standard of comparison) than THI in this difficult-to-image population, with no reported side effects. For both ejection fraction and ventricular volumes, the observer variability was least for CON, intermediate with THI, and greatest for fundamental imaging.

Suppurative Acinetobacter baumanii thyroiditis with bacteremic pneumonia: case report and review

Suppurative thyroiditis is rare, and the major pathogens are Staphylococcus and Streptococcus species. We present a case caused by Acinetobacter baumanii, which has never before been reported. We review another 191 cases from the English-language literature (1980 to April 1997) and make a comparison with a review of 224 cases (1900-1980). As the numbers of immunocompromised patients increase, cases of suppurative thyroiditis are increasing. Pneumocystis carinii has become an important pathogen. Most patients (83.1%) with bacterial infections were euthyroid, whereas those with fungal or mycobacterial infections tended to be hypothyroid (62.5%) and hyperthyroid (50%), respectively.

Ambulatory care training in cardiology: redefining the traditional arena of learning

Fiscal restraint, consolidation of resources and services, and restructuring have led to changes in the case mix of teaching hospitals, which places limitations on the education of medical trainees in this environment and has sparked growing interest in the teaching of clinical medicine in the ambulatory care setting. Early attempts to emphasize ambulatory care in training programs, and the strengths and weaknesses of this teaching forum are reviewed, and a model of its application to the discipline of cardiology is offered.

Clinical profiles in adult diabetic ketoacidotic patients in a tertiary referral medical center in southern Taiwan

Diabetic ketoacidosis (DKA) is not rare among adults. We retrospectively analyzed the precipitating factors, diabetic history, clinical features, and outcomes of adult DKA patients treated at a tertiary referral medical center in southern Taiwan between January 1994 and May 1996. Seventy-eight patients, aged from 18 to 80 years (median 47), had 87 episodes of DKA (44 males had 49 episodes; 34 females had 38 episodes). Twenty-two episodes occurred in patients with no history of diabetes mellitus (age 18-77 yr, median 40.5). The most common precipitating factor was infection (53 episodes), especially in patients aged more than 40 years. Fifteen patients died during the 87 episodes, giving a case fatality rate of 17%; DKA was precipitated by cerebrovascular accidents in two of the 15 patients and by infection in 13. Among the 53 episodes precipitated by infection, multiple logistic regression analysis showed that old age, requirement for endotracheal intubation, and low body temperature on arrival were associated with fatality. Of the 63 patients who were discharged, 39 required insulin therapy; plasma glucose was well-controlled by oral hypoglycemic agents or diet in only eight (age 29-75 yr, median 57; hemoglobin A1c 5.1-7.8%, median 6.6). The high rate of previously undiagnosed diabetes in adult DKA patients indicates a deficiency in early recognition of, and timely therapy for, diabetes in southern Taiwan.