Hospital-Based Health Professionals' Perceptions of Frailty in Older People.

BACKGROUND AND OBJECTIVES: There is a high prevalence of frailty amongst older patients in hospital settings. Frailty guidelines exist but implementation to date has been challenging. Understanding health professional attitudes, knowledge, and beliefs about frailty is critical in understanding barriers and enablers to guideline implementation and the aim of this study was to understand these in rehabilitation multidisciplinary teams in hospital settings. RESEARCH DESIGN AND METHODS: Twenty-three semi-structured interviews were conducted with health professionals working in multi-disciplinary teams on geriatric and rehabilitation wards in Adelaide and Sydney, Australia. Interviews were audio recorded, transcribed, and coded by two researchers. A codebook was created and interviews re-coded and applied to the Framework Method of thematic analysis. RESULTS: Three domains were developed: diagnosing frailty, communicating about frailty, and managing frailty. Within these domains, eight themes were identified: (1) diagnosing frailty has questionable benefits, (2) clinicians don't use frailty screening tools, (3) frailty can be diagnosed on appearance and history, (4) frailty has a stigma, (5) clinicians don't use the word "frail" with patients, (6) frailty isn't always reversible, (7) there is a lack of continuity of care after acute admission, and (8) the community setting lacks resources. DISCUSSION AND IMPLICATIONS: Implementation of frailty guidelines will remain challenging while staff avoid using the term "frail", don't perceive benefit of using screening tools, and focus on the individual aspects of frailty rather than the syndrome holistically. Clinical champions and education about frailty identification, reversibility, management, and communication techniques may improve the implementation of frailty guidelines in hospitals.

Arbuscular Mycorrhizal Fungi Drive Organo-Mineral Association in Iron Ore Tailings: Unravelling Microstructure at the Submicron Scale by Synchrotron-Based FTIR and STXM-NEXAFS.

Arbuscular mycorrhizal (AM) fungi play an important role in organic matter (OM) stabilization in Fe ore tailings for eco-engineered soil formation. However, little has been understood about the AM fungi-derived organic signature and organo-mineral interactions in situ at the submicron scale. In this study, a compartmentalized cultivation system was used to investigate the role of AM fungi in OM formation and stabilization in tailings. Particularly, microspectroscopic analyses including synchrotron-based transmission Fourier transform infrared (FTIR) and scanning transmission X-ray microspectroscopy combined with near-edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) were employed to characterize the chemical signatures at the AM fungal-mineral and mineral-OM interfaces at the submicron scale. The results indicated that AM fungal mycelia developed well in the tailings and entangled mineral particles for aggregation. AM fungal colonization enhanced N-rich OM stabilization through organo-mineral association. Bulk spectroscopic analysis together with FTIR mapping revealed that fungi-derived lipids, proteins, and carbohydrates were associated with Fe/Si minerals. Furthermore, STXM-NEXAFS analysis revealed that AM fungi-derived aromatic, aliphatic, and carboxylic/amide compounds were heterogeneously distributed and trapped by Fe(II)/Fe(III)-bearing minerals originating from biotite-like minerals weathering. These findings imply that AM fungi can stimulate mineral weathering and provide organic substances to associate with minerals, contributing to OM stabilization and aggregate formation as key processes for eco-engineered soil formation in tailings.

Enhancing shear strength and handleability of dewatered clay-rich coal tailings for dry-stacking.

Mineral tailings dams pose high pollution risks to the environment and catastrophic failures. Dry stacking has been identified as a promising alternative to mitigate these risks and offers various benefits to the mining industry but lacks systematic research outcomes. To facilitate dry stacking, coal tailings slurries were dewatered using either filtration or centrifugation methods, resulting in a semi-solid form (cake) that can be safely disposed of. The handleability and disposability of these cakes are greatly influenced by the selection of chemical aids (such as polymer flocculants) and the mechanical dewatering technique employed. The effects of polyacrylamide (PAM) flocculants with a range of molecular weight, charge, and charge density are presented. Coal tailings samples with differences in clay mineralogy were dewatered using press filtration, solid bowl centrifugation, and natural air drying. Handleability and disposability of the tailings were assessed by their rheological properties, including yield stress, adhesive and cohesive stresses, and stickiness. Residue moisture, type of polymer flocculants, and clay mineralogy were found to be crucial factors affecting the handleability and disposability of the dewatered cakes. The tailing yield stress (shear strength) increased as the solid concentration increased. In the semi-solid regime (above 60 wt% solids), the tailings displayed stiff exponential growth. Similar trends were observed for stickiness and adhesive/cohesive energy of the tailings with a steel (truck) surface. Adding polymer flocculants increased the shear strength of the dewatered tailings by 10-15%, thus favouring disposability. However, the polymer selection for coal tailing handling and processing is a trade-off between its disposability and handleability, which requires a multi-criteria decision-making process. The current results also suggested that cationic PAM could be most suitable for dewatering by press filtration, while anionic PAM should be selected for dewatering by solid bowl centrifugation.

Ecological engineering of iron ore tailings into useable soils for sustainable rehabilitation.

Ecological engineering of soil formation in tailings is an emerging technology toward sustainable rehabilitation of iron (Fe) ore tailings landscapes worldwide, which requires the formation of well-organized and stable soil aggregates in finely textured tailings. Here, we demonstrate an approach using microbial and rhizosphere processes to progressively drive aggregate formation and development in Fe ore tailings. The aggregates were initially formed through the agglomeration of mineral particles by organic cements derived from microbial decomposition of exogenous organic matter. The aggregate stability was consolidated by colloidal nanosized Fe(III)-Si minerals formed during Fe-bearing primary mineral weathering driven by rhizosphere biogeochemical processes of pioneer plants. From these findings, we proposed a conceptual model for progressive aggregate structure development in the tailings with Fe(III)-Si rich cements as core nuclei. This renewable resource dependent eco-engineering approach opens a sustainable pathway to achieve resilient tailings rehabilitation without resorting to excavating natural soil resources.

Implementation of a frailty intervention in the transition from hospital to home: a realist process evaluation protocol for the FORTRESS trial.

INTRODUCTION: Frailty in Older people: Rehabilitation, Treatment, Research Examining Separate Settings (the FORTRESS study) is a multisite, hybrid type II, stepped wedge, cluster, randomised trial examining the uptake and outcomes of a frailty intervention. The intervention is based on the 2017 Asia Pacific Clinical Practice Guidelines for the Management of Frailty and begins in the acute hospital setting and transitions to the community. The success of the intervention will require individual and organisational behaviour change within a dynamic health system. This process evaluation will examine the multiple variables at play in the context and mechanism of the frailty intervention to enhance understanding of the outcomes of the FORTRESS study and how the outcomes can be translated from the trial into broader practice. METHODS AND ANALYSIS: The FORTRESS intervention will recruit participants from six wards in New South Wales and South Australia, Australia. Participants of the process evaluation will include trial investigators, ward-based clinicians, FORTRESS implementation clinicians, general practitioners and FORTRESS participants. The process evaluation has been designed using realist methodology and will occur in parallel to the FORTRESS trial. A mixed-method approach will be used with qualitative and quantitative data collected from interviews, questionnaires, checklists and outcome assessments. Qualitative and quantitative data will be examined for CMOCs (Context, Mechanism, Outcome Configurations) and programme theories will be developed, tested and refined. This will facilitate development of more generalisable theories to inform translation of frailty intervention within complex healthcare systems. ETHICS AND DISSEMINATION: Ethical approval for the FORTRESS trial, inclusive of the process evaluation, has been obtained from the Northern Sydney Local Health District Human Research Ethics Committees reference number 2020/ETH01057. Recruitment for the FORTRESS trial uses opt-out consent. Dissemination will be via publications, conferences and social media. TRIAL REGISTRATION NUMBER: ACTRN12620000760976p (FORTRESS trial).

Probing interfacial water structure induced by charge reversal and hydrophobicity of silica surface in the presence of divalent heavy metal ions using sum frequency generation spectroscopy.

HYPOTHESIS: Adsorption of divalent heavy metal ions (DHMIs) at the mineral-water interfaces changes interfacial chemical species and charges, interfacial water structure, Stern (SL), and diffuse (DL) layers. These molecular changes can be detected by probing changing orientation and hydrogen-bond network of interfacial water molecules in response to changing local charges and hydrophobicity. EXPERIMENTS: Sum-frequency generation (SFG) spectroscopy was used to probe changes in vibrational resonances of interfacial OH vs. DHMI concentration and pH. SFG spectra were deconvoluted using the measured surface potential and maximum entropy method in conjunction with the electrical double-layer theory for the SL and DL structures and correlated by hydrophobicity. FINDINGS: Three surface charge reversals (CRs) were detected at low (CR1), medium (CR2), and high (CR3) pHs. Unlike CR1, SFG signals were minimized at CR2 and CR3 for DHMIs-silica systems highlighting considerable alterations in the structure of interfacial waters due to the inner-sphere sorption of metal hydroxo complexes. SFG results showed "hydrophobic-like" stretching modes at > 3600 cm-1 for Pb-, Cu-, and Zn-treated silica. However, contact angle measurements revealed the hydrophobization of silica only in the presence of Pb(II), as confirmed by an in-depth SFG analysis of the hydrogen-bond network of the interfacial water molecules in the SL.

Smartphone app-based intervention for reducing stress, depression, and anxiety in caregivers of people with dementia in Vietnam: Study protocol for a pilot randomized controlled trial.

Objectives: This study aims to: (1) identify the information required by family caregivers of people with dementia to be targeted within our dementia family caregiver intervention and (2) test the feasibility of the intervention and methodology to underpin a fully powered randomized controlled trial. Methods: The study setting will be the Department of Geriatrics at Gia Dinh People's Hospital in Ho Chi Minh City. Inclusion criteria will be the family caregivers of people with dementia living in the community, who attend the Department and use smartphones. In phase 1, we will identify the intervention content with family caregivers of people with dementia through 20 in-depth interviews to determine what information and skills they need. In phase 2, a pilot randomized control trial design will be conducted, with 60 family caregivers of people with dementia being assigned to the intervention or control group by the block randomization method with a ratio of 1:1. The intervention will include weekly, online, psycho-educational, group sessions hosted on the Zalo app. The participants will complete questionnaires at baseline, immediately postintervention, and 3-month postintervention. The feasibility of the intervention and methodology will be assessed, including the rates of recruitment, retention, completion of assessments, and acceptability of the intervention. Results: The required information and skills in phase 1 may include dealing with worrying behavior changes in people with dementia, emotional support, and seeking support sources. The rates of recruitment, retention, completion of assessments, and acceptability of the intervention will be obtained in phase 2. The scores of symptoms of stress, depression, and anxiety in the intervention group may be lower than those in the control group at postintervention and 3-month postintervention. Conclusion: The study will provide a foundation for a fully powered clinical trial for the smartphone app-based intervention to reduce stress, depression, and anxiety among family caregivers of people with dementia in Vietnam.

Undergraduate Medical Education Reform in Viet Nam for a Primary Health Care Workforce.

Strong primary health care (PHC) systems require a robust PHC workforce. Traditionally, medical education takes place in academic medical centres that favour subspecialty care rather than PHC settings. This may undervalue primary care as a career and contribute to a shortage of PHC workers. However, designing undergraduate medical education curricula that incorporate early experiences in clinical care delivery at PHC sites remains a challenge, including in many low- and middle-income countries (LMICs). This paper describes how a collaboration between Harvard Medical School and five medical schools in Vietnam, and in-country collaborations among the Vietnamese medical schools, facilitated curricular innovation and co-creation of coursework relevant to PHC through the development of a Practice of Medicine (POM) course. The collaboration implemented a technical assistance strategy consisting of in-person workshops, focused virtual consultations, on-site 'office hours', site visits and observations to each of the five medical universities, and immersion trips to support the creation and implementation of the POM course. A pilot program was started at a single site and then scaled nationally using local customisation, experience, and expertise utilising a train-the-trainers approach. As a result, five new POM courses have been developed by five Vietnamese institutions. Fifty Vietnamese faculty received training to lead the POM course development, and 228 community-based preceptors have been trained to teach students at PHC sites. A total of 52 new PHC and community-based clinical training sites have been added, and 3,615 students have completed or are currently going through a POM course. This experience can serve as a model for future academic collaborations to support the development of a robust PHC workforce for the 21st century.

Binary-FRET reveals transient excited-state structure associated with activity-dependent CaMKII - NR2B binding and adaptation.

Synaptic functions are mediated and modulated by a coordinated choreography of protein conformational changes and interactions in response to intracellular calcium dynamics. Time-lapse Förster resonance energy transfer can be used to study the dynamics of both conformational changes and protein-protein interactions simultaneously under physiological conditions if two resonance energy transfer reactions can be multiplexed. Binary-FRET is a technique developed to independently monitor the dynamics of calcium-calmodulin dependent protein kinase-II catalytic-domain pair separation in the holoenzyme, and its role in establishing activity-dependent holoenzyme affinity for the NR2B binding fragment of the N-methyl-D-aspartate receptor. Here we show that a transient excited-state intermediate exists where paired catalytic-domains in the holoenzyme first separate prior to subsequent NR2B association. Additionally, at non-saturating free calcium concentrations, our multiplexed approach reveals that the holoenzyme exhibits a biochemical form of plasticity, calcium dependent adaptation of T-site ligand binding affinity.

Use of the double-paddle anterolateral thigh flap for locally advanced tongue carcinoma requiring second site reconstruction.

BACKGROUND: Advanced oral tongue carcinoma can present with extension beyond the oral cavity. Operative defects after resection may involve multiple anatomical sites and significantly impact speech and swallowing. Dependence on long-term enteral feeding is not uncommon for these patients. The anterolateral thigh (ALT) flap is one of the most reliable and flexible flaps used in the reconstruction of total and subtotal tongue defects. The double-paddle flap modification may be a more suitable option for complex oral tongue defects after advanced tumor ablation. METHODS: Case series of 31 patients with oral tongue squamous cell carcinoma that were classified as stage IV. The age of patients ranged from 32 to 63 years. We designed the double-paddle ALT flaps to reconstruct the two-site surgical defects (tongue defect and pharynx or neck skin defect). Postoperative viability of the flap was checked by clinical observation. The last examination was performed at 3-months after the completion of adjuvant chemoradiotherapy. The functional capacity of our patients was evaluated by three physicians (Head and Neck Surgeon, Radiation Oncologist, and Physiatrist) using a Speech Intelligibility Score and the Functional Oral Intake Scale. RESULTS: A total of 31 patients with surgical defects after total or subtotal tongue resection for cancer underwent double-paddle ALT flaps for reconstruction from March 2018 to December 2019. The dimension of flaps from 8 × 12 cm to 10 × 18 cm were divided into double-paddle from 8 × 5 cm to 10 × 10 cm. There was one case of pedicle thrombosis, one case of postoperative bleeding, three cases of neck infection, and six cases of salivary fistula. Our patients were seen in follow up from 6 to 36 months, with median follow-up of 23.5 months. The survival rate of ALT flap was 100%. All of our patients achieved an oral diet by 9 months after surgery. The mean score speech intelligibility was 2.74 ± 0.68 (4-point ordinal scale). The 2-year disease-free survival rate was 61.3%. CONCLUSIONS: The double-paddle ALT flap is a reliable flap suitable for oral defects involving multiple subsites after ablative procedures. The majority of patients demonstrated acceptable functional rehabilitation. CLINICAL QUESTION/ LEVEL OF EVIDENCE: Therapeutic, IV.

Helicobacter pylori Eradication Efficacy of Therapy Based on the Antimicrobial Susceptibility in Children with Gastritis and Peptic Ulcer in Mekong Delta, Vietnam.

BACKGROUND: The efficacy of Helicobacter pylori (H. pylori) eradication therapy for children is currently low, and antibiotic resistance is a significant cause of treatment failure. The purpose of this study was to evaluate the H. pylori eradication efficacy of therapy based on antimicrobial susceptibility in pediatric patients with gastritis and peptic ulcer. METHODS: This study was conducted at Can Tho Children's Hospital and Can Tho University of Medicine and Pharmacy Hospital between March 2019 and April 2022. We performed an upper gastrointestinal endoscopy, cultured H. pylori from biopsies of gastric mucosa, determined antibiotic sensitivities to H. pylori by the E-test method, and treated eradication based on the antibiotic susceptibilities of bacteria. After at least 4 weeks of eradication therapy, we assessed the effectiveness of treatment with a breath test. RESULTS: Among 237 children recruited in this study, 48.9% were boys and 51.1% were girls, and the mean age was 10.03 ± 2.53 years. We determined that 80.6% of H. pylori were resistant to clarithromycin, as well as amoxicillin, metronidazole, levofloxacin, and tetracycline, at 71.7%, 49.4%, 45.1%, and 11.4%, respectively. The overall eradication rate of H. pylori was 83.1% (172/207). Among therapies tailored to antimicrobial susceptibility, the bismuth quadruple regimen achieved the greatest success, but the efficacy of triple therapy with esomeprazole + AMX + CLR/MTZ was low. CONCLUSIONS: Tailored eradication therapy was highly successful in our study but did not achieve over 90%. We recommend that in countries with a high prevalence of antibiotic resistance in H. pylori strains, particularly where the amoxicillin-resistance rate of H. pylori is high, therapy tailored to antimicrobial susceptibility should be used as first-line therapy, and bismuth and tetracycline should be added to enhance the eradication efficacy in children.

Transforming medical education to strengthen the health professional training in Viet Nam: A case study.

The competency-based undergraduate curriculum reform at the University of Medicine and Pharmacy at Ho Chi Minh City, Faculty of Medicine (UMP-FM) is detailed and reviewed in reference to the instructional and institutional reforms, and enabling actions recommended by the Lancet 2010 Commission for Health Professional Education. Key objectives are to: revise the overall 6-year curriculum to be more integrated and competency-based; reinforce students' knowledge application, problem-solving, clinical competence, self-directed learning and soft skills; develop a comprehensive and performance-based student assessment programme; and establish a comprehensive quality monitoring programme to facilitate changes and improvements. New features include early introduction to the practice of medicine, family- and community-based medicine, professionalism, interprofessional education, electives experiences, and a scholarly project. Institutional reform introduces a faculty development programme, joint planning mechanism, a "culture of critical inquiry", and a transparent faculty reward system. Lessons learnt from the curriculum reform at UMP-FM could be helpful to medical schools from low- and middle-income countries considering transitioning from a traditional to a competency-based curriculum. Funding: This work receives no external funding.

Frailty in older people: Rehabilitation Treatment Research Examining Separate Settings (FORTRESS): protocol for a hybrid type II stepped wedge, cluster, randomised trial.

BACKGROUND: Frailty in older people is associated with increased risk of falls, longer length of stay in hospital, increased risk of institutionalisation and death. Frailty can be measured using validated tools. Multi-component frailty interventions are recommended in clinical practice guidelines but are not routinely implemented in clinical practice. METHODS: The Frailty in Older people: Rehabilitation, Treatment, Research Examining Separate Settings (FORTRESS) trial is a multisite, hybrid type II, stepped wedge, cluster, randomised trial with blinded assessment and intention-to-treat analysis being conducted in Australia. The study aims to determine the effectiveness and cost-effectiveness of an embedded individualised multicomponent frailty intervention (commencing in hospital and continuing in the community) on readmissions, frailty and quality of life when compared with usual care. Frail older people admitted to study wards with no significant cognitive impairment, who are expected to return home after discharge, will be eligible to participate. Participants will receive extra sessions of physiotherapy, pharmacy, and dietetics during their admission. A Community Implementation Facilitator will coordinate implementation of the frailty management strategies and primary network liaison. The primary outcome is number of days of non-elective hospital readmissions during 12 month follow-up period. Secondary outcomes include frailty status measured using the FRAIL scale; quality of life measured using the EQ-5D-5L; and time-to-event for readmission and readmission rates. The total cost of delivering the intervention will be assessed, and cost-effectiveness analyses will be conducted. Economic evaluation will include analyses for health outcomes measured in terms of the main clinical outcomes. Implementation outcomes will be collected as part of a process evaluation. Recruitment commenced in 2020 and we are aiming to recruit 732 participants over the three-year duration of the study. DISCUSSION: This study will reveal whether intervening with frail older people to address factors contributing to frailty can reduce hospital readmissions and improve frailty status and quality of life. If the FORTRESS intervention provides a clinically significant and cost-effective result, it will demonstrate an improved approach to treating frail patients, both in hospital and when they return home. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12620000760976p . ANZCTR registered 24 July 2020.

Co-solidification of bauxite residue and coal ash into indurated monolith via ambient geopolymerisation for in situ environmental application.

Bauxite residues generated from alumina refineries worldwide have accumulated to more than 4 billion tons, at an annual increment of ~ 0.15 billion tons. It is imperative and urgent for the alumina sector to develop field-operable disposal solutions for rapid and cost-effective stabilisation of alkaline bauxite residues (BR) in the storage facility to minimise/prevent potential environmental risks. Taking advantage of the availability of coal ash (CA) on site, we studied a feasible way to synthesise geopolymer from active (amorphous) aluminosilicate components of BR and CA via the alkaline hydrolysis under ambient conditions. The new geopolymeric binder effectively solidifies BR-CA mixtures into indurated monoliths whose unconstrained compressive strength (UCS) can reach as high as ~ 20 MPa after 8 weeks. The Full Factorial Experimental Design was used to study relative influences of BR:CA ratio, modulus of activating solution, and H2O/Na2O ratio on UCS. Micro-spectroscopic structural analyses using electron-dispersive X-ray spectroscopy and X-ray Photoelectron Spectroscopy suggested a co-occurrence of cement-like calcium aluminosilicate hydrate (C-A-S-H) and Na-rich aluminosilicate 3D-extended network (geopolymer) within the binder phase. The advantage of this ambient geopolymerisation, without resorting to elevated temperature curing, renders a feasible way of valorising BR and CA for environmental management of alkaline wastes at alumina refineries.

The Risk of Preoperative Central Nervous System-Acting Medications on Delirium Following Hip or Knee Surgery: A Matched Case-Control Study.

INTRODUCTION: Medicines acting on the central nervous system can increase the risk of postoperative delirium, but the specific medicines associated with greatest risk remain unclear. OBJECTIVES: We aimed to examine the risk of individual central nervous system-acting medicines used preoperatively on delirium after hip or knee surgery. METHODS: A matched case-control study was conducted using data from the Australian Government Department of Veterans' Affairs. We included people aged 65 years or older who had knee or hip surgery between 2000 and 2019. People with hip or knee surgery who developed postoperative delirium were cases and controls were people with hip or knee surgery but who did not develop postoperative delirium. Use of medicines including anxiolytics, sedatives, and hypnotics, opioid analgesics and antidepressants prior to surgery was compared between cases and controls. RESULTS: A total of 2614 patient cases with postoperative delirium were matched by same sex, age (±2 years), and year of admission (±2 years) with 7842 controls without postoperative delirium. Cases were more likely to be exposed to nitrazepam (odds ratio [OR] = 1.81, 95% confidence interval [CI] 1.24-2.64), sertraline (OR = 1.50, 95% CI 1.20-1.87), mirtazapine (OR = 1.38, 95% CI 1.11-1.74), venlafaxine (OR = 1.42, 95% CI 1.02-1.98), citalopram (OR = 1.54, 95% CI 1.19-1.99), escitalopram (OR = 1.42, 95% CI 1.06-1.89) or fluvoxamine (OR = 5.01, 95% CI 2.15-11.68) prior to surgery than controls. At the class level, exposure to benzodiazepines (OR = 1.20, 95% CI 1.05-1.37) and antidepressants (OR = 1.64, 95% CI 1.47-1.83) prior to surgery was significantly higher in cases than in controls. The numbers needed to treat to harm for one additional delirium case were 43 for sertraline, 40 for citalopram, 57 for mirtazapine and 26 for nitrazepam. Whereas, the numbers needed to treat to harm were found to be 20 for sertraline, 17 for citalopram, 19 for mirtazapine and 10 for nitrazepam in the 85 years or older age group, indicating that the harmful effect of these medicines is pronounced as age advances. CONCLUSIONS: People who developed delirium following hip or knee surgery were more likely to be exposed to nitrazepam, sertraline, mirtazapine, venlafaxine, citalopram, escitalopram or fluvoxamine at the time of admission for surgery. Planning to reduce use of these medicines well prior to surgery may decrease the risk of postoperative delirium.

Unravelling in-situ hardpan properties and functions in capping sulfidic Cu-Pb-Zn tailings and forming a duplex soil system cover.

Developing alternative approaches to cap and rehabilitate the large areas of tailings landscapes is critical for sustainable development of mining industry. This study revealed the potential of an in-situ hardpan-based duplex soil system as an un-conventional approach to rehabilitate sulfidic Cu-Pb-Zn tailings. Under a shallow silicious soil cover, a massive and consistent hardpan horizon had been formed in-situ at the surface layer of tailings across the trial area, which physically separated root zones (i.e., silica soil cover) from the un-weathered tailings underneath, prevented capillary enrichment of acidity and soluble solutes into the root zones, and sustained native plant growth for more than a decade. Precipitation of Si-rich ferric complexes were attributed to the stabilisation/solidification of the sulfidic tailing. The hardpan layer possesses a highly compacted texture, a low-percolating pore network, and extreme resistance to water movement in the hardpan horizon. Further, the hardpans directly interfacing with plant roots in the soil cover were geochemically stabilised and attenuated, with very low levels of soluble metal(loid)s and a circumneutral pH condition. This case study would serve as a good incentive to develop bio-chemical engineering methodology building on current knowledge for achieving sustainable rehabilitation of sulfidic and metallic tailings in future.

Biochar mediated uranium immobilization in magnetite rich Cu tailings subject to organic matter amendment and native plant colonization.

Organic matter (OM) amendments and plant colonization can accelerate mineral weathering and soil formation in metal mine tailings for ecological rehabilitation. However, the weathering effects may dissolve uranium (U)-bearing minerals (e.g., ianthinite) and increase U dissolution in porewater and seepages. The present study aimed to characterize the U solubility and distribution among different fractions and investigate if biochar (BC) could decrease soluble U levels and facilitate U immobilization in the OM-amended and plant-colonized tailings. A native plant species, Red Flinders grass (Iseilema vaginiflorum) was cultivated in the tailings for four weeks, which were amended with sugarcane residue (SR) with or without BC addition. The results showed that OM amendment and plant colonization increased porewater U concentrations by almost 10 folds from ~ 0.2 mg L-1 to > 2.0 mg L-1. The BC addition decreased porewater U concentrations by 40%. Further micro-spectroscopic analysis revealed that U was immobilized through adsorption onto BC porous surfaces, via possibly complexing with oxygen-rich organic groups. Besides, the BC amendment facilitated U sequestration by secondary Fe minerals in the tailings. These findings provide important information about U biogeochemistry in Cu-tailings mediated by BC, OM and rhizosphere interactions for mitigating potential pollution risks of tailings rehabilitation.

Chemodiversity of Dissolved Organic Matter and Its Molecular Changes Driven by Rhizosphere Activities in Fe Ore Tailings Undergoing Eco-Engineered Pedogenesis.

Dissolved organic matter (DOM) plays an important role in soil structure and biogeochemical function development, which are fundamental for the eco-engineering of tailings-soil formation to underpin sustainable tailings rehabilitation. In the present study, we have characterized the DOM composition and its molecular changes in an alkaline Fe ore tailing primed with organic matter (OM) amendment and plant colonization. The results demonstrated that microbial OM decomposition dramatically increased DOM richness and average molecular weight, as well as its degree of unsaturation, aromaticity, and oxidation in the tailings. Plant colonization drove molecular shifts of DOM by depleting the unsaturated compounds with a high value of nominal oxidation state of carbon (NOSC), such as tannin-like and carboxyl-rich polycyclic-like compounds. This may be partially related to their sequestration by secondary Fe-Si minerals formed from rhizosphere-driven mineral weathering. Furthermore, the molecular shifts of DOM may have also resulted from plant-regulated microbial community changes, which further influenced DOM molecules through microbial-DOM interactions. These findings contribute to the understanding of DOM biogeochemistry and ecofunctionality in the tailings during early pedogenesis driven by OM input and pioneer plant/microbial colonization, providing an important basis for the development of strategies and technologies toward the eco-engineering of tailings-soil formation.

Survival after out-of-hospital cardiac arrest, Viet Nam: multicentre prospective cohort study.

OBJECTIVE: To investigate factors associated with survival after out-of-hospital cardiac arrest in Viet Nam. METHODS: We did a multicentre prospective observational study of people (> 18 years) presenting with out-of-hospital cardiac arrest (not caused by trauma) to three tertiary hospitals in Viet Nam from February 2014 to December 2018. We collected data on characteristics, management and outcomes of patients with out-of-hospital cardiac arrest and compared these data by type of transportation to hospital and survival to hospital admission. We assessed factors associated with survival to admission to and discharge from hospital using logistic regression analysis. FINDINGS: Of 590 eligible people with out-of-hospital cardiac arrest, 440 (74.6%) were male and the mean age was 56.1 years (standard deviation: 17.2). Only 24.2% (143/590) of these people survived to hospital admission and 14.1% (83/590) survived to hospital discharge. Most cardiac arrests (67.8%; 400/590) occurred at home, 79.4% (444/559) were witnessed by bystanders and 22.3% (124/555) were given cardiopulmonary resuscitation by a bystander. Only 8.6% (51/590) of the people were taken to hospital by the emergency medical services and 32.2% (49/152) received pre-hospital defibrillation. Pre-hospital defibrillation (odds ratio, OR: 3.90; 95% confidence interval, CI: 1.54-9.90) and return of spontaneous circulation in the emergency department (OR: 2.89; 95% CI: 1.03-8.12) were associated with survival to hospital admission. Hypothermia therapy during post-resuscitation care was associated with survival to discharge (OR: 5.44; 95% CI: 2.33-12.74). CONCLUSION: Improvements are needed in the emergency medical services in Viet Nam such as increasing bystander cardiopulmonary resuscitation and public access defibrillation, and improving ambulance and post-resuscitation care.