Biology subjects

Nurmi, P.

Publications and source records attributed to Nurmi, P..

3 recordsLinked to original sources

bioRxiv2026

Operando Failure Diagnosis and Performance Dynamics in Microbial Fuel Cells Treating Mine Waste

Artisanal gold-mining tailings carry dissolved mercury, copper and lead at concentrations requiring treatment before discharge. Bench-scale microbial fuel cells (MFCs) offer passive treatment of such streams, but exhibit operational variability that obscures whether removal is biologically driven. This study applies an integrated diagnostic framework to two bench-scale systems treating tailings from two artisanal gold-mining districts in Ecuador. System 1 evaluated Micractinium inermum bio-augmentation, while System 2 compared Psychrobacter alimentarius- and Trichococcus patagoniensis-dominated anodic consortia. The framework combines paired time-series statistical modeling, an adaptive percentile-floor change-point detector, equivalent-circuit modeling, and baseline-corrected XRD/FTIR spectroscopy. In System 1, treatment reduced mercury from 0.042 to 0.0027-0.0148 mg L^-1 and copper from 2.79 to 0.130-1.837 mg L^-1. Against the applicable discharge limits, copper complied in six of eight reactor--phase combinations, whereas mercury exceeded its limit throughout, identifying it as the limiting contaminant. Removal was governed by system-level physicochemical processes rather than algal-specific biocatalysis, with the non-algal control matching or exceeding the augmented reactors. Paired per-day testing showed that algal bio-augmentation conferred no voltage advantage under stable operation (+0.17%) but a +27.54% gain under diurnal perturbation, periodicity analysis attributed these shifts to the 24-h chamber photoperiod. An adaptive change-point detector distinguished recoverable excursions from terminal structural collapse in both systems, and equivalent-circuit fitting attributed System 2 consortium power difference to internal resistance and open-circuit voltage. The framework separates biological treatment effects from mechanical failure, supporting automated health monitoring in bio-electrochemical wastewater treatment.

bioengineering↗

bioRxiv2025

Magnetoencephalography reveals adaptive neural reorganization maintaining lexical-semantic proficiency in healthy aging

Although semantic cognition remains behaviorally stable with age, neuroimaging studies report age-related alterations in response to semantic context. We aimed to reconcile these inconsistent findings by combining behavioral and magnetoencephalography (MEG) measures and examined the neural mechanisms underlying lexical-semantic processing in healthy aging. Forty-six Finnish-speaking adults (25 female) across younger (22- 32 years) and older (62 - 69 years) cohorts performed a semantic congruency judgment task on word pairs. Both age groups performed the task with high accuracy, with older adults responding faster than young. While advancing age was not associated with impaired task performance, MEG revealed neural reorganization in the old compared to young adults. Young participants exhibited the canonical N400 effect in the left temporal cortex 300 - 400 ms post-stimulus, followed by a Late Positive Complex (LPC), whereas older adults showed less pronounced congruency effects, and the activation distribution was shifted toward frontal and bilateral regions. Despite the absence of the canonical N400 effect in older participants, multivariate time-resolved decoding demonstrated that the congruency effect was decodable from the MEG responses in both groups from [~]300 ms post-stimulus, indicating preserved sensitivity to congruency with age. Decoding performance correlated with response time, suggesting that increased neural separation between semantic concepts facilitates rapid decision-making. Critically, age groups were distinguishable based on their neural responses 300 - 800 ms post-stimulus, reflecting functional reorganization in older adults. Overall, our findings suggest that healthy aging involves adaptive reconfiguration of neural systems, supported by experience-driven strategies that preserve semantic proficiency despite broader age-related cognitive changes.

neuroscience↗

bioRxiv2023

Human sensorimotor resting state beta events and 1/f response show good test-retest reliability

Neurological conditions affecting the sensorimotor system have a profound impact on individuals physical independence and are associated with a considerable socioeconomic burden. Reliable functional biomarkers allowing early diagnosis of these conditions or targeting treatment and rehabilitation can reduce this burden. Magnetoencephalography (MEG) can non-invasively measure the brains salient rhythmic patterns such as the somatomotor ( rolandic) rhythm. This rhythm shows intermittent high amplitude events in the beta (14-30 Hz) frequency range which predict behavior across tasks and species and are altered by neurological diseases affecting the sensorimotor system. Thus, the sensorimotor resting beta phenotype is a promising candidate biomarker of sensorimotor function. A prerequisite for use as a biomarker is that it can be quantified reliably across different measurement sessions. Here, using MEG, we assessed the test-retest stability of spontaneously occurring sensorimotor power spectral characteristics, including both aperiodic (1/f) as well as beta band fluctuations ( beta events) in a cohort of 50 healthy human controls. Test-retest reliability across two separate measurement sessions was assessed using the intraclass correlation coefficient (ICC). Beta events were determined using a thresholding-based approach on a narrow-band filtered amplitude envelope obtained using Morlet wavelet decomposition across a range of parameters (recording length, amplitude threshold and filtering bandwidth). We find that both aperiodic power spectral features as well as several beta event characteristics show good to excellent testretest stability. Especially aperiodic component power spectral features (ICC 0.77-0.88), but also measures of beta event amplitude (ICC 0.74-0.82) were found to be very stable, while measures of individual beta event duration were less reliable, especially for the left hemisphere (ICC right [~]0.7, left [~]0.55). Recordings of 2-3 minutes were sufficient to obtain stable results for most parameters. Important for potential clinical applications, automatization of beta event extraction was successful in 86 % of cases. Beta event rate and duration measures were more sensitive to analysis parameters than the measures of event amplitude. The results suggest the sensorimotor beta phenotype is a stable feature of an individuals resting brain activity even for short, 2-3 minute recordings which can be easily measured in patient populations, facilitating its use as a potential clinical biomarker.

neuroscience↗