First Measurement of Drift-Alfvén Wave Polarization in Magnetically Confined Fusion Plasmas.

Polarization of drift-Alfvén waves, defined as the ratio of electrostatic to electromagnetic fluctuations, has remained unmeasurable in fusion plasmas for decades, despite its pivotal role in understanding wave dynamics and their impact on plasmas. We report the first measurements of drift-Alfvén wave polarization in a hot, magnetically confined plasma. The breakthrough is enabled by a novel methodology developed from gyrokinetic theory, utilizing fluctuations of electron temperature and density. Analysis of data from the DIII-D tokamak reveals that the waves above the geodesic acoustic mode frequency exhibit dominant electromagnetic polarization, whereas lower-frequency waves show a mix of electromagnetic and electrostatic polarization, indicating a strong coupling between shear Alfvén waves and drift-acoustic waves.

Direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride.

A strategy for direct synthesis of phenanthrenyl triflates from 1-biphenylyl-2-diazo-2-aryl ketones and triflic anhydride is described. The reaction of 1-biphenylyl-2-diazo-2-aryl ketones with triflic anhydride proceeded smoothly in the presence of 2,6-di-tert-butylpyridine under mild conditions to produce phenanthrenyl triflates in high to excellent yields. The phenanthrenyl triflate products were demonstrated to be utilized as coupling partners in various coupling reactions. The proposed mechanism involves an intramolecular Friedel-Crafts reaction of a vinyl cation intermediate formed in situ.

Bird Beta Diversity in Sharp Contrasting Altai Landscapes: Locality Connectivity Is the Influential Factor on Community Composition.

Located on the southwest slope and plain areas of the Altai Mountains in China, this study aims to explore bird composition variation (beta diversity) in mountain landscape (metacommunity M), riparian landscape (metacommunity R), desert landscape (metacommunity D) and across the three landscapes (metacommunity A), and to assess how patch connectivity with environmental and spatial factors influence species distributional patterns across multiple metacommunities. In 78 transect lines over the study area, 9724 detections of 139 bird species were detected. We calculated the beta diversity, its turnover and nestedness components in four metacommunities. We used the variation partitioning method to investigate the relative importance between the environment, spatial variation and locality connectivity in driving bird community composition variation. We found high beta diversities with a small contribution of nestedness components in all four metacommunities. When only a single set of predictors is contained in the model, the predictor that best explains the variation of bird community composition is connectivity in metacommunity M, R and D and spatial predictor in metacommunity A. In all three sets of predictors, 73.8~85.4% of variations of community composition can be explained in the four metacommunities, and connectivity always contributed the most. High beta diversity and a high turnover component imply that regional-scale conservation efforts should be thought of as preserving overall biodiversity. A conservation strategy is to keep stepping-stone habitats with good connectivity in the middle of the riparian landscape. Along with the Altai-Sayan biodiversity ecoregion, the desert and riparian environments are essential for birds residing in the mountainous terrain. Furthermore, they should be regarded as integral parts of the ecoregion.

Chemically enhanced primary treatment of municipal wastewater with ferrate(VI).

Chemically enhanced primary treatment (CEPT) with ferrate(VI), a multifunctional treatment agent, was investigated for the treatment of municipal wastewater in a laboratory-scale study. The treatment performance was evaluated at different ferrate(VI) doses (0.0-9.0 mg/L as Fe) and pH (6.0 and 7.5). The optimal removals of total suspended solids (TSS) (52%), total chemical oxygen demand (COD) (34%), and total phosphorus (47%) were achieved at the highest ferrate(VI) dose (9.0 mg/L as Fe) and the weakly alkaline condition (pH 7.5). The pollutant abatements principally ascribed to the formation of large-sized aggregate and ensuing sedimentation fell within the reported ranges of CEPT with traditional coagulants. However, different from conventional CEPT, ferrate(VI) appreciably removed recalcitrant dissolved organic phosphorus (49%) and simultaneously inactivated total coliform (3.30 log removal) and Escherichia coli (3.67 log removal) at 9.0 mg/L Fe(VI) and pH 7.5. The CEPT with ferrate(VI) offers an innovative alternative for improving municipal wastewater treatment. PRACTITIONER POINTS: Ferrate(VI) represents a promising agent for chemically enhanced primary treatment (CEPT) of municipal wastewater. CEPT with ferrate(VI) can effectively alleviate TSS, total COD, and total P via the formation of large-sized aggregates and ensuing sedimentation. Ferrate(VI) can substantially remove recalcitrant dissolved organic phosphorus in municipal wastewater. Different from other CEPT coagulants, ferrate(VI) can appreciably inactivate bacterial indicators during CEPT. Higher ferrate(VI) dose and weakly alkaline pH favor the performance of ferrate(VI) CEPT.

Cascade Reaction of Arylboronic Acids and 2'-Cyano-biaryl-2-aldehyde N-Tosylhydrazones: Access to Functionalized 9-Amino-10-arylphenanthrenes.

An efficient, general, and convenient protocol for the synthesis of functionalized 9-amino-10-arylphenanthrene derivatives using a catalyst-free cascade reaction of arylboronic acids and 2'-cyano-biaryl-2-aldehyde N-tosylhydrazones is described. The synthesis was carried out via simple experimental conditions using Na2CO3 in 1,4-dioxane as a solvent. Moreover, the 9-amino-10-arylphenanthrene compounds were also obtained on a gram scale and further derivatized to synthesize the fused phenanthrene derivatives.

Monitoring of Gas Emboli During Hysteroscopic Surgery: A Prospective Study.

OBJECTIVES: Previous studies have demonstrated a high frequency of gas emboli during hysteroscopy, but guidelines for the prevention, early detection, and intervention of gas embolism during hysteroscopic procedures are still lacking. This study aimed to gain a clearer understanding of risk factors and specific signs and symptoms associated with gas emboli. METHODS: This prospective study enrolled 120 women scheduled for hysteroscopy using 5% glucose as distension medium. The gas bubbles were monitored sequentially in internal iliac vein, common iliac vein, inferior vena cava, superior vena cava, heart, and pulmonary artery under the gray-scale imaging of Doppler ultrasound. The frequency, extent, and the hemodynamic and respiratory effects of gas emboli were evaluated. The interventions and outcomes were recorded. The risk factors associated with gas emboli, and their relationship with the frequency and extent of gas emboli, were assessed. RESULTS: In our study, evidence of gas emboli under Doppler ultrasound monitoring was observed in 44 (36.7%) patients. The operation was continued and finished as soon as possible for patients presenting with stable vital signs or transient hemodynamic and respiratory changes, which resolved spontaneously without intervention. The operation was paused for patients presenting with significant hemodynamic changes or loss of consciousness, and the operation was resumed shortly after resumption of stable vital signs following symptomatic treatment. All patients in our study finished the operation and recovered without developing serious complications. Data analysis showed prolonged procedure duration and increased bleeding volume were both positively correlated with the frequency and extent of gas emboli. CONCLUSION: Our study demonstrated a high frequency of gas emboli during hysteroscopy. Doppler ultrasonic monitoring combined with a clearer understanding of specific signs, symptoms, and risk factors will facilitate early detection and intervention of gas emboli during hysteroscopy.

Clinical outcomes of "complete, partially complete, and incomplete" revascularisation at five-year follow-up after percutaneous intervention of unprotected left main coronary artery disease with drug-eluting stents.

AIMS: The study aimed to examine five-year clinical outcomes of complete (CR), partially complete (PCR), and incomplete revascularisation (ICR) in patients with unprotected left main coronary artery (ULMCA) disease treated with drug-eluting stents (DES). Completeness of revascularisation, defined as revascularisation of all vessels ≥1.5 or 2.5 mm in diameter, has been shown to correlate with outcomes after percutaneous coronary intervention (PCI). There are no data to compare revascularisation strategies on long-term clinical outcomes in patients undergoing PCI of ULMCA disease. METHODS AND RESULTS: This prospective registry enrolled 910 consecutive patients with ULMCA disease undergoing PCI with DES implantation. CR included patients who had a successful revascularisation of all diseased segments with diameter ≥1.5 mm. PCR included patients who had successful revascularisation of all diseased segments with diameter ≥2.5 mm. ICR included patients who did not achieve revascularisation for all diseased segments of diameter ≥2.5 mm. The primary endpoint was the incidence of major adverse cardiac events (MACE: a composite of cardiac death, myocardial infarction and repeat revascularisation) at five-year follow-up. CR was achieved in 386 (42.4%), PCR in 227 (25.0%), and ICR in 297 (32.6%) patients. Patients with ICR had a significantly higher rate of MACE (29.6% vs. 22.5% and 15.5%, p<0.001) and all-cause mortality (12.5% vs. 7.0% and 6.2%; p=0.006) than those with CR and PCR at five-year follow-up. After propensity score matching, patients with CR vs. PCR had similar incidences of MACE (hazard ratio [HR]: 1.16, 95% confidence interval [CI]: 0.78-1.74, p=0.46), mortality (HR: 1.27, 95% CI: 0.61-2.63, p=0.53), and cardiac death (1.8% vs. 4.5%; HR: 2.56, 95% CI: 0.80-8.17, p=0.11). On multivariable logistic regression analysis, ICR appears to be an outcome of poor clinical characteristics, comorbidities and complex coronary anatomy. CONCLUSIONS: In the treatment of patients with ULMCA disease, ICR was associated with worse long-term clinical outcomes than CR and PCR. PCR has clinical outcomes similar to CR in patients with ULMCA disease treated with DES.

Randomized Comparison of FFR-Guided and Angiography-Guided Provisional Stenting of True Coronary Bifurcation Lesions: The DKCRUSH-VI Trial (Double Kissing Crush Versus Provisional Stenting Technique for Treatment of Coronary Bifurcation Lesions VI).

OBJECTIVES: This study sought to compare the outcomes of fractional flow reserve (FFR)-guided and angiography (Angio)-guided provisional side-branch (SB) stenting for true coronary bifurcation lesions. BACKGROUND: Angio-guided provisional SB stenting after stenting of the main vessel provides favorable outcomes for the majority of coronary bifurcation lesions. Whether an FFR-guided provisional stenting approach is superior has not been studied. METHODS: A total of 320 patients with single Medina 1,1,1 and 0,1,1 coronary bifurcation lesions undergoing stenting with a provisional SB approach were randomly assigned 1:1 to Angio-guided and FFR-guided groups. SB stenting was performed for Thrombolysis In Myocardial Infarction flow grade<3, ostial SB stenosis>70%, or greater than type A dissection after main vessel stenting in the Angio-guided group and for SB-FFR<0.80 in the FFR-guided group. The primary endpoint was the 1-year composite rate of major adverse cardiac events (cardiac death, myocardial infarction, and clinically driven target vessel revascularization). RESULTS: Comparing the Angio-guided and FFR-guided groups, treatment of the SB (balloon or stenting) was performed in 63.1% and 56.3% of lesions respectively (p=0.07); stenting of the SB was attempted in 38.1% and 25.9%, respectively (p=0.01); and, when attempted, stenting was successful in 83.6% and 73.3% of SBs, respectively (p=0.01). The 1-year composite major adverse cardiac event rate was 18.1% in both groups (hazard ratio: 0.91, 95% confidence interval: 0.48 to 1.88; p=1.00). The 1-year target vessel revascularization and stent thrombosis rates were 6.9% and 5.6% (p=0.82) and 1.3% and 0.6% (p=0.56) in the Angio-guided and FFR-guided groups, respectively. CONCLUSIONS: In this multicenter, randomized trial, angiographic and FFR guidance of provisional SB stenting of true coronary bifurcation lesions provided similar 1-year clinical outcomes. (Randomized Study on DK Crush Technique Versus Provisional Stenting Technique for Coronary Artery Bifurcation Lesions; ChiCTR-TRC-07000015).

Plasma-resistivity-induced strong damping of the kinetic resistive wall mode.

An energy-principle-based dispersion relation is derived for the resistive wall mode, which incorporates both the drift kinetic resonance between the mode and energetic particles and the resistive layer physics. The equivalence between the energy-principle approach and the resistive layer matching approach is first demonstrated for the resistive plasma resistive wall mode. As a key new result, it is found that the resistive wall mode, coupled to the favorable average curvature stabilization inside the resistive layer (as well as the toroidal plasma flow), can be substantially more stable than that predicted by drift kinetic theory with fast ion stabilization, but with the ideal fluid assumption. Since the layer stabilization becomes stronger with decreasing plasma resistivity, this regime is favorable for reactor scale, high-temperature fusion devices.

Efficacy and safety of bone marrow cell transplantation for chronic ischemic heart disease: a meta-analysis.

BACKGROUND: Although bone marrow-derived cells (BMCs) have shown great therapeutic potential in patients with chronic ischemic heart disease (CIHD), the exact efficacy and safety of BMCs therapy is still not completely defined. MATERIAL/METHODS: We searched PubMed, OVID, EMBASE, the Cochrane Library, and ClinicalTrials.gov and finally identified 20 qualified trials in this meta-analysis. Assessment of efficacy was based on left ventricular ejection fraction (LVEF), left ventricular end-systolic volume (LVESV), and left ventricular end-diastolic volume (LVEDV) improvement, by weighted mean difference (WMD) with 95% confidence intervals (CIs). RESULTS of all-cause death, ventricular arrhythmia, recurrent myocardial infarction, and cerebrovascular accident were pooled to assess safety. Subgroup analysis was performed by stratifying RCTs into 2 subgroups of those with revascularization and without revascularization. RESULTS: BMC transplantation significantly improved LVEF in patients with revascularization (3.35%, 95% CI 0.72% to 5.97%, p=0.01; I2=85%) and without revascularization (3.05%, 95% CI 0.65% to 5.45%, p=0.01; I2=86%). In patients without revascularization, BMC transplantation was associated with significantly decreased LVESV (-11.75 ml, 95% CI -17.81 ml to -5.69 ml, p=0.0001; I2=81%), and LVEDV (-7.80 ml, 95% CI -15.31 ml to -0.29 ml, p=0.04; I2=39%). Subgroup analysis showed that the route of transplantation, baseline LVEF, and type of cells delivered could influence the efficacy of BMC transplantation. CONCLUSIONS: Autologous transplantation of BMCs was safe and effective for patients who were candidates for revascularization with CABG/PCI and those who were not. However, large clinical trials and long-term follow-up are required to confirm these benefits.

Comparison of clinical outcomes of Chinese men and women after coronary stenting for coronary artery disease: a multi-center retrospective analysis of 4,334 patients.

The outcome differences between Chinese male and female patients within one-year follow-up after percutaneous coronary intervention (PCI) with stent remain unclear. The present study was aimed to compare clinical outcomes in such two populations. From May 1999 to December 2009, 4,334 patients with acute myocardial infarction (MI), unstable angina, stable angina, or silent ischemia, who underwent PCI, were registered at our centers. Among these, 3,089 were men and 1,245 were women. We compared these groups with respect to the primary outcomes of MI and secondary outcomes including a composite of major adverse cardiac events (MACE) including cardiac death, MI, target lesion revascularization, target vessel revascularization (TVR), stent thrombosis (ST), definite ST and probable ST at one-year follow-up. Chinese male patients had a higher MACE rate (13% vs. 10.7%, P  =  0.039), mainly led by TVR (9.09% vs. 6.98%, P = 0.024) at one year, which was significantly different than female patients. Chinese male and female patients showed a significant difference on MACEs. However, there was no significant difference with respect to MI between these groups.

Safflower yellow inhibits angiotensin II-induced adventitial fibroblast proliferation and migration.

Safflower yellow (SY) has been widely used in Chinese medicine for the treatment of ischemic cardiocerebrovascular disease. Recent studies have indicated that SY has a reverse effect on vascular remodeling (VR). However, its detailed mechanisms require further study to provide more scientific evidence for the clinical treatment of VR. This study aims to investigate the effects of SY on angiotensin II (Ang II)-induced cell proliferation, migration, apoptosis, and extracellular matrix in rat aortic adventitial fibroblasts (AFs). The proliferation and migration rates of AFs treated with Ang II for 24 h were higher than those of untreated AFs; and increases in the expression of p-ERK1/2, AP-1, collagen I, and collagen III were observed. Treatment with SY significantly downregulated cell proliferation, migration, and the expression of p-ERK1/2, AP-1, collagen I, and collagen III. We also found that the cell percentage of apoptosis of AFs treated with Ang II for 24 h was lower than those of untreated AFs. After treatment with SY, the percentage of apoptosis was increased. SY exhibits anti-proliferative, anti-migratory, and pro-apoptotic activities in rat aortic AFs, perhaps through the Ang II/ERK/AP-1 signaling pathway. The present findings may provide new clues regarding the potential function of SY to treat or prevent VR.

Two-year clinical outcomes after coronary drug-eluting stent placement in Chinese men and women: a multicenter, prospective registry study.

BACKGROUND: Previous studies have reported a discrepancy in baseline characteristics and outcomes after percutaneous coronary intervention between men and women. However, this finding has never been verified in the Chinese population. The present study analyzed two-year clinical outcomes after placement of coronary drug-eluting stents in Chinese men and women. METHODS: From January 2005 to December 2010, a total of 3804 Chinese patients (2776 men, 1028 women) who underwent drug-eluting stent implantation were studied prospectively. The primary endpoint was the composite major adverse cardiac event (MACE) rate, including myocardial infarction, cardiac death, and target vessel revascularization at two years. Stent thrombosis served as the safety endpoint. Propensity score matching was used to compare the adjusted MACE rate between the two groups. RESULTS: At two-year follow-up, unadjusted rates of myocardial infarction, non-ST segment elevation myocardial infarction, target vessel revascularization, and MACE were significantly different between men (6.84%, 4.6%, 13.1%, and 21.7%, respectively) and women (3.8% [P = 0.001], 2.0% [P < 0.001] 10.3% [P = 0.025], and 16.3% [P < 0.001], respectively). After propensity score matching, there were no significant differences in composite MACE and individual endpoints at two years between the genders. CONCLUSION: Despite all the unfavorable risk factor clustering in women and complex coronary disease in men, the two-year clinical outcomes after coronary stent placement were comparable between Chinese women and men.

Five-year clinical follow-up of unprotected left main bifurcation lesion stenting: one-stent versus two-stent techniques versus double-kissing crush technique.

AIMS: The present study aimed to compare the long-term (five-year) safety and efficacy between the one-stent, two-stent and double-kissing (DK) crush strategies, utilising drug-eluting stents, for unprotected left main coronary artery (ULMCA) bifurcation lesions. METHODS AND RESULTS: Between March 2004 and April 2007, 633 consecutive patients with ULMCA bifurcation lesions (232 in the one-stent group and 401 in the two-stent group) were prospectively enrolled. The primary endpoint was the occurrence of major adverse cardiac events (MACE), a composite of cardiac death, myocardial infarction (MI), and target vessel revascularisation (TVR), at five-year follow-up. Patients in the the two-stent group were classified as DK crush (n=155) and other two-stent techniques (culotte, T-stenting, kissing stenting and classical crush, n=246). Forty-seven (16.8%) patients in the one-stent group crossed over to the two-stent group. The one-stent group was associated with an increased incidence of MI compared to the two-stent approach (10.5% vs. 5.5%, p=0.025). The crude rate of MACE at five years was 28.0% in the one-stent group and 28.4% in the two-stent group (p=0.927). DK crush was associated with a significantly decreased five-year MACE compared to the other two-stent approaches or the one-stent approach (DK crush: 14.8% vs. other two-stent approaches: 37.0%, one-stent approach: 28.0%, p<0.001). The main benefit of DK crush primarily appeared to be secondary to a reduction in TVR (7.7% vs. 30.5% vs. 18.1%, p<0.001). By Cox regression analyses, the non-DK crush two-stent technique, a high SYNTAX Score (≥33) or New Risk Stratification (NERS) score (>20), and incomplete revascularisation were shown to be independent predictors of MACE at five-year follow-up. CONCLUSIONS: With distal left main true bifurcations, the two-stent technique (excluding DK crush) is an independent predictor of long-term MACE. DK crush is associated with more favourable long-term clinical outcomes. Confirmation of these findings is required from randomised controlled trials.

Observation of lobes near the X point in resonant magnetic perturbation experiments on MAST.

The application of nonaxisymmetric resonant magnetic perturbations (RMPs) with a toroidal mode number n = 6 in the MAST tokamak produces a significant reduction in plasma energy loss associated with type-I edge localized modes (ELMs), the first such observation with n > 3. During the ELM mitigated stage clear lobe structures are observed in visible-light imaging of the X-point region. These lobes or manifold structures, that were predicted previously, have been observed for the first time in a range of discharges and their appearance is correlated with the effect of RMPs on the plasma; i.e., they only appear above a threshold when a density pump out is observed or when the ELM frequency is increased. They appear to be correlated with the RMPs penetrating the plasma and may be important in explaining why the ELM frequency increases. The number and location of the structures observed can be well described using vacuum modeling. Differences in radial extent and poloidal width from vacuum modeling are likely to be due to a combination of transport effects and plasma screening.

Mechanisms and clinical significance of quality of final kissing balloon inflation in patients with true bifurcation lesions treated by crush stenting technique.

BACKGROUND: The mechanisms responsible for the occurrence of a kissing unsatisfied (KUS) result after classical crush stenting remain unclear. The present study aimed at analyzing the mechanisms and clinical significance of KUS. METHODS: Two hundred and thirteen patients with true bifurcation lesions treated with classical crush stenting and final kissing balloon inflation (FKBI) were assigned to upper, middle, and lower groups according to the position of the side branch re-wiring assessed by visual estimation, quantitative coronary analysis (QCA) and intravascular ultrasound (IVUS). Angiographic follow-up was indexed at 12 months. RESULTS: The upper group was characterized by a larger bifurcation angle of 55.53 degrees +/- 25.25 degrees (P = 0.030) and a longer procedural time (42.43 +/- 23.92) minutes (P = 0.015). The overall rate of KUS by visual estimation was 10.48%, with 5.4% in the upper group, 3.9% in middle group, and 36.1% in lower group (P < 0.001). For the diagnosis of KUS, visual inspection demonstrated a good correlation with both QCA and IVUS. Smaller stent diameter was the main reason for KUS in the upper group, while extra-stent side wire location, or re-wire in a low position was the main mechanism attributed to KUS in the lower group. The Lower group had more restenosis, with most restenotic lesions at a lower position of the side branch ostium. KUS (HR 1.652, 95% CI 1.332 - 2.088, P < 0.001) and re-wiring position (HR 2.341, 95% CI 1.780 - 4.329, P < 0.001) were two independent predictors of side branch restenosis. Re-wiring position (OR 0.458, 95%CI 0.336 - 0.874, P = 0.001) and side stent expansion (OR 3.122, 95%CI 2.883 - 5.061, P = 0.014) were factors predicting the findings of KUS. CONCLUSIONS: Side wire outside side stents resulted in more KUS and restenosis. Different restenotic lesion types reflected individual mechanisms contributing to the development of plaque proliferation.

Adsorbed polyelectrolyte coatings decrease Fe(0) nanoparticle reactivity with TCE in water: conceptual model and mechanisms.

The surfaces of reactive nanoscale zerovalent iron (NZVI) particles used for in situ groundwater remediation are modified with polymers or polyelectrolytes to enhance colloidal stability and mobility in the subsurface. However, surface modification decreases NZVI reactivity. Here, the TCE dechlorination rate and reaction products are measured as a function of adsorbed polyelectrolyte mass for three commercially available polyelectrolytes used for NZVI surface modification including poly(styrene sulfonate) (PSS), carboxymethyl cellulose (CMC), and polyaspartate (PAP). The adsorbed mass, extended layer thickness, and TCE-polyelectrolyte partition coefficient are measured and used to explain the effect of adsorbed polyelectrolyte on NZVI reactivity. For all modifiers, the dechlorination rate constant decreased nonlinearly with increasing surface excess, with a maximum of a 24-fold decrease in reactivity. The TCE dechlorination pathways were not affected. Consistent with Scheutjens-Fleer theory for homopolymer adsorption, the nonlinear relationship between the dechlorination rate and the surface excess of adsorbed polyelectrolyte suggests that adsorbed polyelectrolyte decreases reactivity primarily by blocking reactive surface sites at low surface excess where they adsorb relatively flat onto the NZVI surface, and by a combination of site blocking and decreasing the aqueous TCE concentration at the NZVI surface due to partitioning of TCE to adsorbed polyelectrolytes. This explanation is also consistent with the effect of adsorbed polyelectrolyte on acetylene formation. This conceptual model should apply to other medium and high molecular weight polymeric surface modifiers on nanoparticles, and potentially to adsorbed natural organic matter.

Effect of TCE concentration and dissolved groundwater solutes on NZVI-promoted TCE dechlorination and H2 evolution.

Nanoscale zero-valent iron (NZVI) is used to remediate contaminated groundwater plumes and contaminant source zones. The target contaminant concentration and groundwater solutes (NO3-, Cl-, HCO3-, SO4(2-), and HPO4(2-)) should affect the NZVI longevity and reactivity with target contaminants, but these effects are not well understood. This study evaluates the effect of trichloroethylene (TCE) concentration and common dissolved groundwater solutes on the rates of NZVI-promoted TCE dechlorination and H2 evolution in batch reactors. Both model systems and real groundwater are evaluated. The TCE reaction rate constant was unaffected by TCE concentration for [TCE] < or = 0.46 mM and decreased by less than a factor of 2 for further increases in TCE concentration up to water saturation (8.4 mM). For [TCE] > or = 0.46 mM, acetylene formation increased, and the total amount of H2 evolved at the end of the particle reactive lifetime decreased with increasing [TCE], indicating a higher Fe0 utilization efficiency for TCE dechlorination. Common groundwater anions (5mN) had a minor effect on H2 evolution but inhibited TCE reduction up to 7-fold in increasing order of Cl- < SO4(2-) < HCO3- < HPO4(2). This order is consistent with their affinity to form complexes with iron oxide. Nitrate, a NZVI-reducible groundwater solute, present at 0.2 and 1 mN did not affect the rate of TCE reduction but increased acetylene production and decreased H2 evolution. NO3- present at > 3 mM slowed TCE dechlorination due to surface passivation. NO3- present at 5 mM stopped TCE dechlorination and H2 evolution after 3 days. Dissolved solutes accounted for the observed decrease of NZVI reactivity for TCE dechlorination in natural groundwater when the total organic content was small (< 1 mg/L).

Effect of particle age (Fe0 content) and solution pH on NZVI reactivity: H2 evolution and TCE dechlorination.

Subsurface injection of nanoscale zerovalent iron (NZVI) has been used for the in situ remediation of chlorinated solvent plumes and DNAPL source zones. Due to the cost of materials and placement,the efficacy of this approach depends on the NZVI reactivity and longevity, selectivity for the target contaminant relative to nonspecific corrosion to yield H2, and access to the Fe0 in the particles. Both the reaction pH and the age of the particles (i.e., Fe0 content) could affect NZVI reactivity and longevity. Here, the rates of H2 evolution and trichloroethene (TCE) reduction are measured over the lifetime of the particles and at solution pH ranging from 6.5 to 8.9. Crystalline reactive nanoscale iron particles (RNIP) with different initial Fe0 weight percent (48%, 36%, 34%, 27%, and 9.6%) but similar specific surface area were studied. At the equilibrium pH for a Fe(OH)2/H2O system (pH = 8.9), RNIP exhibited first-order decay for Fe0 corrosion (H2 evolution) with respect to Fe0 content with a Fe0 half-life time of 90-180 days. A stable surface area-normalized TCE reduction rate constant 1.0 x 10(-3)L x hr(-1) x m(-2) was observed after 20 days and remained constant for 160 days, while the Fe0 content of the particles decreased by half, suggesting that TCE reduction is zero-order with respect to the Fe0 content of the particle. Solution pH affected H2 evolution and TCE reduction to a different extent. Decreasing pH from 8.9 to 6.5 increased the H2 evolution rate constant 27 fold from 0.008 to 0.22 day(-1), but the TCE dechlorination rate constant only doubled. The dissimilarities between the reaction orders of H2 evolution and TCE dechlorination with respect to both Fe0 content and H+ concentration suggest that different rate controlling steps are involved for the reduction reactions.

TCE dechlorination rates, pathways, and efficiency of nanoscale iron particles with different properties.

Nanoscale Fe0 particles are a promising technology for in situ remediation of trichloroethene (TCE) plumes and TCE-DNAPL source areas, butthe physical and chemical properties controlling their reactivity are not yet understood. Here, the TCE reaction rates, pathways, and efficiency of two nanoscale Fe0 particles are measured in batch reactors: particles synthesized from sodium borohydride reduction of ferrous iron (Fe/B) and commercially available particles (RNIP). Reactivity was determined under iron-limited (high [TCE]) and excess iron (low [TCE]) conditions and with and without added H2. Particle efficiency, defined as the fraction of the Fe0 in the particles that is used to dechlorinate TCE, was determined under iron-limited conditions. Both particles had a core/shell structure and similar specific surface areas (approximately 30 m2/g). Using excess iron, Fe/B transformed TCE into ethane (80%) and C3-C6 coupling products (20%). The measured surface area normalized pseudo-first-order rate constant for Fe/B (1.4 x 10(-)2 L.h(-1).m(-2) is approximately 4-fold higher than for RNIP (3.1 x 10-(3) L.h(-1).m(-2). All the Fe0 in Fe/B was accessible for TCE dechlorination, and 92 +/- 0.7% of the Fe0 was used to reduce TCE. For Fe/B, H2 evolved from reduction of water (H+) was subsequently used for TCE dechlorination, and adding H2 to the reactor increased both the dechlorination rate and the mass of TCE reduced, indicating that a catalytic pathway exists. RNIP yielded unsaturated products (acetylene and ethene). Nearly half (46%) of the Fe0 in RNIP was unavailable for TCE dechlorination over the course of the experiment and remained in the particles. Adding H2 did not change the reaction rate or efficiency of RNIP. Despite this, the mass of TCE dechlorinated per mass of Fe0 added was similar for both particles due to the less saturated products formed from RNIP. The oxide shell composition and the boron content are the most likely causes for the differences between the particle types.