Pain in rheumatoid arthritis: a seven-year follow-up study of pain distribution and factors associated with transition from and to chronic widespread pain.

OBJECTIVE: To study transitions from and to chronic widespread pain (CWP) over 7 years in patients with rheumatoid arthritis (RA). METHOD: Two postal questionnaires were sent to patients included in the BARFOT (Better Anti-Rheumatic Pharmacotherapy) study, the first in 2010 and the second in 2017. The questionnaires assessed pain, number of tender and swollen joints, functional disability, health-related quality of life (HRQoL), pharmacological treatment, lifestyle factors, and patient-reported body mass index (BMI). The responders to both questionnaires were divided into three groups according to the reported pain duration and distribution: patients having no chronic pain (NCP), chronic regional pain (CRP), and CWP. RESULTS: In all, 953 patients answered the questionnaires at both time-points. One-third (324) of the patients reported CWP in 2010, and 140 (43%) of the patients had transition to NCP or CRP in 2017. In multivariate logistic regression models, adjusting for age, gender, and disease duration, transition from CWP was associated with normal BMI, fewer tender joints, less pain, less fatigue, fewer pain regions, less disability, better HRQoL, and biologic treatment. In 2010, 628 patients reported NCP or CRP, whereas 114 of them reported CWP in 2017. Transition to CWP was associated with female gender, obesity, more tender and swollen joints, higher pain-related variables, worse disability, and worse HRQoL. CONCLUSION: There are modifiable factors associated with transitions from and to CWP that could be identified. Paying attention to these factors could improve pain treatment in the management of RA.

Distribution of erosions in hands and feet at the time for the diagnosis of RA and during 8-year follow-up.

BACKGROUND: Joint destruction in rheumatoid arthritis (RA) is usually evaluated by radiographs of both hands and feet, while the inflammatory status mostly is evaluated by DAS28 which, however, does not include the feet. OBJECTIVES: To investigate the distribution of erosions in hands and feet in early RA over 8 years and its potential clinical implications. Furthermore, the group of patients never showing erosions has been addressed. METHODS: This study comprises 1041 patients from the BARFOT study of patients with early RA. Radiographs of hands and feet were performed at baseline, 1, 2, 5, and 8 years and evaluated by the Sharp van der Heijde scoring (SHS) method (32 joints in the hands and 12 in the feet). Disease activity was measured by DAS28, SR, CRP, and function with HAQ. RESULTS: In the feet, there were significantly more eroded joints in percent of examined joints than in the hands at all time points. Patients with erosions only in the feet were younger, more often seropositive and smokers. They had significantly lower baseline DAS28, than the patients with erosions only in the hands. The patients without erosions over time were, at diagnosis, significantly younger and less frequently seropositive compared with patients having erosions. CONCLUSIONS: This study highlights the importance of evaluating the feet in patients with RA, both with clinical examinations and with imaging and lends support to the notion that seropositivity and smoking are risk factors for erosive disease. Further studies of patients with nonerosive disease are needed. KEY POINTS: • Foot problems are common in RA • This study emphasizes the limitations of DAS28 and Sharp van der Heijde score as regards evaluating disease activity and radiographic damage • This study highlights the importance of evaluating the feet in patients with RA with clinical examinations and imaging • This study also points out the need of further studies of patients with non-erosive RA.

Unacceptable pain in the BARFOT inception cohort of patients with rheumatoid arthritis: a long-term study.

Objectives: Pain is the most common and troublesome complaint in rheumatoid arthritis (RA). This study aimed to assess the prevalence and clinical implications of unacceptable pain in an inception cohort of patients with RA. Method: This study followed 477 patients from the BARFOT (Better Anti-Rheumatic FarmacOTherapy) early RA cohort for 15 years. Unacceptable pain was defined as ≥ 40 mm on a visual analogue scale for pain, while tolerable pain denoted no pain or pain below this cut-off, according to the patient acceptable symptom state concept. Results: Unacceptable pain was frequent. At the 15 year follow-up visit, 34% had unacceptable pain. Patients with unacceptable pain had, compared with patients with tolerable pain, significantly more disease activity, worse patient global assessment, and worse function on the Health Assessment Questionnaire and Signals of Functional Impairment, but the degree of joint destruction was similar. Disease-modifying anti-rheumatic drug treatment was similar, but patients with unacceptable pain were more often treated with corticosteroids. At 15 years, patients with unacceptable pain who were in remission (33%) had less inflammation and better function than those not in remission, suggesting the presence of non-inflammatory causes of pain. Conclusions: In this cohort of patients with RA, pain was frequent and severe, with negative effects on experienced health and function. Unacceptable pain was frequent and occurred also in patients in remission, indicating that pain in RA is multifactorial and should always be regarded as an important concern in itself. The cause of pain should be recognized and treated appropriately.

Optical signatures of single ion tracks in ZnO.

The optical properties of single ion tracks have been studied in ZnO implanted with Ge by combining depth-resolved hyperspectral cathodoluminescence (CL) and photoluminescence (PL) spectroscopy techniques. The results indicate that ZnO is susceptible to implantation doses as low as 108 to 109 cm-2. We demonstrate that the intensity ratio of ionized and neutral donor bound exciton emissions [D+X/D0X] can be used as a tracer for a local band bending both at the surface as well as in the crystal bulk along the ion tracks. The hyperspectral CL imaging performed at 80 K with 50 nm resolution over the regions with single ion tracks permitted direct assessment of the minority carrier diffusion length. The radii of distortion and space charge surrounding single ion tracks were estimated from the 2D distributions of defect-related green emission (GE) and excitonic D+X emission, both normalized with regard to neutral D0X emission, i.e., from the [GE/D0X] and [D+X/D0X] ratio maps. Our results indicate that single ion tracks in ZnO can be resolved up to ion doses of the order of 5 × 109 cm-2, in which defect aggregation along the extended defects obstructs signatures of individual tracks.

Screening for breast cancer-related lymphoedema: self-assessment of symptoms and signs.

INTRODUCTION: In the absence of monitoring programs, those at risk of developing breast cancer-related lymphoedema (BCRL) must detect its development. However, the efficacy of self-assessment for BCRL has not been widely investigated. This study will determine if symptoms and signs of BCRL are associated with lymphoedema detected by bioimpedance spectroscopy (BIS) and whether those with and without BCRL can accurately assess the signs of its presence. METHODS AND RESULTS: Participants with a history of breast cancer (n = 100) reported the presence/absence of symptoms associated with upper limb BCRL and underwent assessment for pitting oedema and differences in tissue texture between their arms (pinch). BIS detected BCRL in 48 women. Women were more likely to have BIS-detected BCRL if they reported swelling (odds ratio (OR), 58.8; 95% CI, 4.9 to 709.4; p = 0.001) or had inter-limb tissue texture differences in their forearm (OR, 73.5; 95% CI, 7.3 to 736.9; p = < 0.001) or upper arm (OR, 23.9; 95% CI, 2.8 to 201.7; p = 0.003). Agreement between therapist and self-assessment of signs of BCRL was almost perfect (kappa, 0.819 to 0.940). A combination of self-reported swelling and/or self-assessed forearm tissue texture difference identified all cases of BIS-detected BCRL. CONCLUSION: Participants accurately identified the presence or absence of physical signs of BCRL in their arm. Perceived swelling and differences in tissue texture in the affected arm were associated with, and sensitive to, BIS-detected BCRL. These findings support the use of self-assessment to determine if BCRL is developing, indicating the need for professional assessment.

Repair of bone erosions in rheumatoid arthritis: a systematic literature review.

Objective: The aim of this study was to review the literature to identify studies reporting repair of erosions in rheumatoid arthritis (RA).Method: A systematic literature search for publications on the repair of erosions was performed in PubMed and Embase, limited to human adults and published in English. Titles, abstracts, and full reports of articles identified were screened by the first author and verified by the second author.Results: The search yielded 411 publications, of which 33 (20 articles and 13 case reports) suggested repair of erosions in RA. There was heterogeneity in study design and different definitions of repair were used. Twelve articles showed strong evidence of repair, in eight articles repair was probable, and in all 13 case reports repair was evident.Conclusion: Repair of erosions does occur in RA. The definition and frequency of repair vary and the possible clinical relevance is unclear, motivating further studies.

Correlated annealing and formation of vacancy-hydrogen related complexes in silicon.

We report on a deep level transient spectroscopy study of annealing kinetics of a deep, vacancy-hydrogen related level, labeled E5*, at 0.42 eV below the conduction band in hydrogen-implanted n-type silicon. The E5* annealing correlates with the formation of another commonly observed vacancy-hydrogen related level, labeled E5, at 0.45 eV below the conduction band. The annealing of E5* and the formation of E5 exhibit first-order kinetics with an activation energy of 1.61 ± 0.07 eV and a pre-factor of ~1013-1014 s-1. The pre-factor indicates a dissociation or structural transformation mechanism. The analysis of electron capture cross-sections for E5* and E5 reveals considerable transition entropies for both states and a temperature dependent capture cross-section for E5*. Two possible identifications of E5* and E5 are put forward. Firstly, E5* can be attributed to V 2H2(-/0) or V 2H3(-/0), which dissociate with the emission of VH (E5). Secondly, E5* and E5 can be assigned to two different configurations of V 3H.

Inclusion of Saccharina latissima in conventional anaerobic digestion systems.

Loading macroalgae into existing anaerobic digestion (AD) plants allows us to overcome challenges such as low digestion efficiencies, trace elements limitation, excessive salinity levels and accumulation of volatile fatty acids (VFAs), observed while digesting algae as a single substrate. In this work, the co-digestion of the brown macroalgae Saccharina latissima with mixed municipal wastewater sludge (WWS) was investigated in mesophilic and thermophilic conditions. The hydraulic retention time (HRT) and the organic loading rate (OLR) were fixed at 19 days and 2.1 g l-1 d-1 of volatile solids (VS), respectively. Initially, WWS was digested alone. Subsequently, a percentage of the total OLR (20%, 50% and finally 80%) was replaced by S. latissima biomass. Optimal digestion conditions were observed at medium-low algae loading (≤50% of total OLR) with an average methane yield close to [Formula: see text] and [Formula: see text] in mesophilic and thermophilic conditions, respectively. The conductivity values increased with the algae loading without inhibiting the digestion process. The viscosities of the reactor sludges revealed decreasing values with reduced WWS loading at both temperatures, enhancing mixing properties.

Hydrogen motion in rutile TiO2.

Uniaxial-stress experiments have been performed for the 3287- and 2445-cm-1 local vibrational modes assigned to the positive charge state of interstitial hydrogen [Formula: see text] and deuterium [Formula: see text], respectively, occurring in mono-crystalline rutile TiO2. The onset of the defect alignment under the stress applied perpendicular to the [001] axis is detected at 165 K (185 K), which corresponds to the activation energy of 0.53 eV (0.58 eV) for interstitial hydrogen (deuterium). Based on these findings the diffusion constants of [Formula: see text] and [Formula: see text] along the [001] axis of TiO2 are determined. The experimental data are complemented by density-functional theory calculations and compared with the earlier results on the diffusion of [Formula: see text]/[Formula: see text] at elevated temperatures up to 700 °C. It is found that the activation energy value deduced from our low-temperature stress measurements yields a very good agreement with the high-temperature data, covering a dynamic range of 12 orders of magnitude.

Interface phenomena in magnetron sputtered Cu2O/ZnO heterostructures.

The interface between ZnO and Cu2O has been predicted to be a good candidate for use in thin film solar cells. However, the high predicted conversion efficiency has yet to be fully realized experimentally. To explore the underlying causes of this we investigate the interface between ZnO and Cu2O in magnetron sputtered samples. Two different sample geometries were made: In the first set thin layers of ZnO were deposited on Cu2O (type A), while in the second set the order was reversed (type B). Using x-ray photoelectron spectroscopy (XPS), an intermediate CuO layer was identified regardless of the order in which the Cu2O and ZnO layers were deposited. The presence of a CuO layer was supported by transmission electron microscopy (TEM) results. Changes in the electron hole screening conditions were observed in CuO near the interface with ZnO, manifested as changes in the relative peak-to-satellite ratio and the degree of asymmetric broadness in the Cu 2p peak. The suppression of the Cu 2p satellite characteristic of CuO may cause the CuO presence to be overlooked and cause errors in determinations of valence band offsets (VBOs). For the type A samples, we compare four different approaches to XPS-based determination of VBO and find that the most reliable results are obtained when the thin CuO layer and the altered screening conditions at the interface were taken into account. The VBOs were found to range between 2.5 eV and 2.8 eV. For the B type samples a reduction of the Cu 2p-LMM Auger parameter was found as compared to bulk Cu2O, indicative of quantum confinement in the Cu2O overlayer.

Electronic properties and morphology of copper oxide/n-type silicon heterostructures.

Silicon-based tandem heterojunction solar cells utilizing cuprous oxide (Cu2O) as the top absorber layer show promise for high-efficiency conversion and low production cost. In the present study, single phase Cu2O films have been realized on n-type Si substrates by reactive magnetron sputtering at 400 °C. The obtained Cu2O/Si heterostructures have subsequently been heat treated at temperatures in the 400-700 °C range in Ar flow and extensively characterized by x-ray diffraction (XRD) measurements, transmission electron microscopy (TEM) imaging and electrical techniques. The Cu2O/Si heterojunction exhibits a current rectification of ~5 orders of magnitude between forward and reverse bias voltages. High resolution cross-sectional TEM-images show the presence of a ~2 nm thick interfacial SiO2 layer between Cu2O and the Si substrate. Heat treatments below 550 °C result in gradual improvement of crystallinity, indicated by XRD. At and above 550 °C, partial phase transition to cupric oxide (CuO) occurs followed by a complete transition at 700 °C. No increase or decrease of the SiO2 layer is observed after the heat treatment at 550 °C. Finally, a thin Cu-silicide layer (Cu3Si) emerges below the SiO2 layer upon annealing at 550 °C. This silicide layer influences the lateral current and voltage distributions, as evidenced by an increasing effective area of the heterojunction diodes.

Rheumatoid arthritis phenotype at presentation differs depending on the number of autoantibodies present.

OBJECTIVES: In rheumatoid arthritis (RA), seropositive and seronegative disease may be two entities with different underlying pathophysiological mechanisms, long-term outcomes and disease presentations. However, the effect of the conjoint presence of multiple autoantibodies, as proxy for a more pronounced humoral autoimmune response, on clinical phenotype remains unclear. Therefore, this study investigates the association between the number of autoantibodies and initial clinical presentation in two independent cohorts of patients with early RA. METHODS: Autoantibody status (rheumatoid factor, anticitrullinated protein antibodies and anticarbamylated protein antibodies) was determined at baseline in the Leiden Early Arthritis Cohort (n=828) and the Swedish BARFOT (Better Anti-Rheumatic Farmaco-Therapy, n=802) study. The association between the number of autoantibodies and baseline clinical characteristics was investigated using univariable and multivariable ordinal regression. RESULTS: In both cohorts, the following independent associations were found in multivariable analysis: patients with a higher number of RA-associated antibodies were younger, more often smokers, had a longer symptom duration and a higher erythrocyte sedimentation rate at presentation compared with patients with few autoantibodies. CONCLUSIONS: The number of autoantibodies, reflecting the breadth of the humoral autoimmune response, is associated with the clinical presentation of RA. Predisease pathophysiology is thus reflected by the initial clinical phenotype.

The association between anti-carbamylated protein (anti-CarP) antibodies and radiographic progression in early rheumatoid arthritis: a study exploring replication and the added value to ACPA and rheumatoid factor.

OBJECTIVE: Anti-carbamylated protein (anti-CarP) antibodies are reported to associate with more radiographic progression within the total rheumatoid arthritis (RA) population and anti-citrullinated peptide antibody (ACPA)-negative subgroup. We explored the association of anti-CarP with radiographic progression in RA and aimed to replicate the association and evaluate the added value of anti-CarP antibodies in relation to ACPA and rheumatoid factor (RF). METHODS: 576 Swedish and 628 Dutch patients with RA (2394 and 3247 sets of radiographs, respectively) were longitudinally studied. Replication was restricted to the Swedish patients. In both cohorts, the association of anti-CarP with radiographic progression was determined in strata of patients with similar ACPA and RF status; results of both cohorts were combined in fixed-effect meta-analyses. The net percentage of patients for whom the radiographic progression in 5 years was additionally correctly classified when adding anti-CarP to a model including ACPA and RF was evaluated. RESULTS: Anti-CarP associated with radiographic progression in the total Swedish RA population (beta=1.11 per year, p=8.75×10-13) and in the ACPA-negative subgroup (beta=1.14 per year, p=0.034). Anti-CarP associated with more radiographic progression in the strata of ACPA-positive/RF-negative, ACPA-negative/RF-positive and ACPA-positive/RF-positive patients with RA (respective p values 0.014, 0.019 and 0.0056). A model including ACPA and RF correctly classified 54% and 57% of the patients; adding anti-CarP to this model did not increase these percentages (54% and 56% were correctly classified). CONCLUSIONS: Anti-CarP antibodies associated with more severe radiographic progression in the total and ACPA-negative RA population. Anti-CarP-positivity had a statistically significant additive value to ACPA and RF, but did not improve correct classification of patients.

Changes in attitudes, intended behaviour, and mental health literacy in the Swedish population 2009-2014: an evaluation of a national antistigma programme.

OBJECTIVE: Public stigma of mental illness is still a major problem where numerous population studies during the last decade have mainly shown no improvements. A Swedish national antistigma campaign has been running 2010-2014. The aim of this study was to investigate changes in public stigma during this period as compared to baseline in 2009. METHODS: Yearly population surveys were made between 2009 and 2014 including assessments of mental health literacy, attitudes, and intended future behaviour. Two surveys were made, one including a nationally representative sample and one including a representative sample from three original campaign regions. Multiple regression analyses, also including age, gender, education, and familiarity with mental illness were made to investigate yearly changes in public stigma compared to baseline. RESULTS: Mental health literacy improved significantly in the campaign regions between 2009 and 2014, as did intended future behaviour. Attitudes toward mental illness also improved significantly. Improvements were also shown in the national population surveys, but the time pattern of these compared to that of the original campaign regions indicated that these changes took place mainly after the campaign had been extended to a further five Swedish regions. CONCLUSION: The results of our surveys suggest that a campaign primarily based on social contact theory and involving people with lived experience of mental illness may, even in a rather short-term perspective, have a significant positive impact on mental health literacy, attitudes, and intentions of social contact with people with mental illness.

Persistently active disease is common in patients with rheumatoid arthritis, particularly in women: a long-term inception cohort study.

OBJECTIVES: Despite improved treatment strategies for rheumatoid arthritis (RA), some patients do not respond satisfactorily. The aim of this study was to investigate the course and outcome of early RA diagnosed during the 1990s and followed for 8 years with a focus on those who did not respond well to treatment. METHOD: This study included 640 patients (66% women) who were enrolled in the BARFOT (Better Anti-Rheumatic PharmacOTherapy) RA inception cohort between the years 1993 and 1999. The 28-joint count Disease Activity Score (DAS28) < 2.6 criteria were used to assess remission. Persistent disease (PD) was defined as absence of remission at all predefined follow-up visits at 1, 2, 5, and 8 years. Function was assessed by Health Assessment Questionnaire (HAQ) and Signals of Functional Impairment (SOFI) scores and radiological joint damage by the Sharp/van der Heijde score (SHS). RESULTS: Of the 640 patients, 214 (37%) had PD (43% of the women and 25% of the men). Over the 8 years of follow-up, patients with PD had significantly worse mean values for patient's global health measured on a visual analogue scale (VAS patGH), VAS pain, HAQ, SOFI, and SHS compared with those in the non-PD group. Multivariate logistic regression analyses revealed that female gender, current smoking, disease activity at baseline, and absence of remission at 6 months independently predicted PD. CONCLUSIONS: Of the patients who entered the early RA inception cohort, 37% suffered a PD course over 8 years. The consequences of PD with regard to general health, pain, function, and joint damage were considerable. Of note, PD was more common in women than in men.

Anticitrullinated protein antibodies and rheumatoid factor are associated with increased mortality but with different causes of death in patients with rheumatoid arthritis: a longitudinal study in three European cohorts.

OBJECTIVE: Patients with rheumatoid arthritis (RA)-related autoantibodies have an increased mortality rate. Different autoantibodies are frequently co-occurring and it is unclear which autoantibodies associate with increased mortality. In addition, association with different causes of death is thus far unexplored. Both questions were addressed in three early RA populations. METHODS: 2331 patients with early RA included in Better Anti-Rheumatic Farmaco-Therapy cohort (BARFOT) (n=805), Norfolk Arthritis Register (NOAR) (n=678) and Leiden Early Arthritis Clinic cohort (EAC) (n=848) were studied. The presence of anticitrullinated protein antibodies (ACPA), rheumatoid factor (RF) and anticarbamylated protein (anti-CarP) antibodies was studied in relation to all-cause and cause-specific mortality, obtained from national death registers. Cox proportional hazards regression models (adjusted for age, sex, smoking and inclusion year) were constructed per cohort; data were combined in inverse-weighted meta-analyses. RESULTS: During 26 300 person-years of observation, 29% of BARFOT patients, 30% of NOAR and 18% of EAC patients died, corresponding to mortality rates of 24.9, 21.0 and 20.8 per 1000 person-years. The HR for all-cause mortality (95% CI) was 1.48 (1.22 to 1.79) for ACPA, 1.47 (1.22 to 1.78) for RF and 1.33 (1.11 to 1.60) for anti-CarP. When including all three antibodies in one model, RF was associated with all-cause mortality independent of other autoantibodies, HR 1.30 (1.04 to 1.63). When subsequently stratifying for death cause, ACPA positivity associated with increased cardiovascular death, HR 1.52 (1.04 to 2.21), and RF with increased neoplasm-related death, HR 1.64 (1.02 to 2.62), and respiratory disease-related death, HR 1.71 (1.01 to 2.88). CONCLUSIONS: The presence of RF in patients with RA associates with an increased overall mortality rate. Cause-specific mortality rates differed between autoantibodies: ACPA associates with increased cardiovascular death and RF with death related to neoplasm and respiratory disease.

MRI evidence of persistent joint inflammation and progressive joint damage despite clinical remission during treatment of early rheumatoid arthritis.

OBJECTIVES: To determine the value of magnetic resonance imaging (MRI) of bones and joints in patients with recent-onset rheumatoid arthritis (RA) treated for 2 years from diagnosis with disease-modifying anti-rheumatic drugs (DMARDs) and glucocorticoids. METHOD: Thirteen patients with early RA were treated according to clinical practice and followed with MRI, radiographs, and Disease Activity Score calculated on 28 joints (DAS28) at inclusion (baseline) and after 1, 4, 7, 13, and 25 months. MRI of the dominant wrist and metacarpophalangeal (MCP) joints were assessed for synovitis, bone oedema, and erosions using the RA MRI Score (RAMRIS) and for tenosynovitis by an MRI tenosynovitis scoring method. Radiographs were assessed by the van der Heijde modified Sharp score (SHS). Clinical remission was defined by a DAS28 < 2.6. RESULTS: MRI at baseline detected inflammation in joints and tendons in all patients as well as erosions in 10 out of 13 patients. Over time, the erosion score increased while the synovitis and tenosynovitis scores remained almost unchanged. Bone oedema strongly correlated with synovitis. Synovitis and tenosynovitis correlated well with the erosion score at baseline but not thereafter. The MRI changes showed that joint damage started early and continued in the presence of persistent synovial and tenosynovial inflammation. CONCLUSIONS: The observations made in this small study suggest that the treatment goal of 'clinical remission' should be supplemented by a 'joint remission' goal. To this end, MRI is an appropriate tool. Further studies are needed to evaluate the optimal use of MRI in early RA.

Effects of trace element addition on process stability during anaerobic co-digestion of OFMSW and slaughterhouse waste.

This study used semi-continuous laboratory scale biogas reactors to simulate the effects of trace-element addition in different combinations, while degrading the organic fraction of municipal solid waste and slaughterhouse waste. The results show that the combined addition of Fe, Co and Ni was superior to the addition of only Fe, Fe and Co or Fe and Ni. However, the addition of only Fe resulted in a more stable process than the combined addition of Fe and Co, perhaps indicating a too efficient acidogenesis and/or homoacetogenesis in relation to a Ni-deprived methanogenic population. The results were observed in terms of higher biogas production (+9%), biogas production rates (+35%) and reduced VFA concentration for combined addition compared to only Fe and Ni. The higher stability was supported by observations of differences in viscosity, intraday VFA- and biogas kinetics as well as by the 16S rRNA gene and 16S rRNA of the methanogens.

Fate of Trace Metals in Anaerobic Digestion.

A challenging, and largely uncharted, area of research in the field of anaerobic digestion science and technology is in understanding the roles of trace metals in enabling biogas production. This is a major knowledge gap and a multifaceted problem involving metal chemistry; physical interactions of metal and solids; microbiology; and technology optimization. Moreover, the fate of trace metals, and the chemical speciation and transport of trace metals in environments--often agricultural lands receiving discharge waters from anaerobic digestion processes--simultaneously represents challenges for environmental protection and opportunities to close process loops in anaerobic digestion.