Evaluating the Association Between Iron Deficiency Anemia and Febrile Convulsion Among Children Aged 6-60 Months Admitted to a Tertiary Care Hospital in Eastern India: A Case-Control Study.

Background and objective Anemia, particularly iron deficiency anemia (IDA), presents a significant global health challenge, particularly among children under the age of five years in developing nations. Concurrently, febrile convulsions (FC) affect up to 5% of neurologically healthy children aged 6-60 months, causing considerable distress among parents. There is a suggested correlation between fever and iron deficiency, which may exacerbate neurological risks, potentially lowering seizure thresholds and increasing the risk of FC. However, studies investigating the relationship between IDA and FC have shown conflicting results. In light of this, this study aimed to explore this relationship among children aged 6-60 months in Eastern India, an area where this association has yet to be thoroughly investigated. Materials and methods The case-control study included children aged 6-60 months. The cases consisted of children presenting with FC, while controls comprised children in the same age group presenting with febrile illness but without seizures. Informed consent was obtained, a detailed history was taken, and clinical examinations were conducted for both groups. Blood investigations were performed to diagnose IDA according to WHO criteria: hemoglobin <11 gm/dl with the classical triad of low mean corpuscular volume (MCV), low mean corpuscular hemoglobin (MCH), and low mean corpuscular hemoglobin concentration (MCHC) for age. Data analysis was performed using the R-based software Jamovi 2.4.8. with appropriate statistical tests. Results We included 81 cases and 80 controls. The study found a statistically significant association between IDA and FC with an odds ratio (OR) of 2.25 [95% confidence interval (CI): 1.03-4.91; p=0.039]. Additionally, the study revealed that hemoglobin levels, MCH, MCV, and MCHC were lower among cases compared to controls, while the red cell distribution width (RDW) was higher. Both these findings regarding RBC indices were statistically significant (p<0.05). Conclusions Our findings indicate a statistically significant association between IDA and FC among children under five years of age. Implementing measures to prevent IDA and strengthening existing strategies may help alleviate the burden of FC in this vulnerable population.

Ending TB in South-East Asia: flagship priority and response transformation.

Over the decades, the global tuberculosis (TB) response has evolved from sanatoria-based treatment to DOTS (Directly Observed Therapy Shortcourse) strategy and the more recent End TB Strategy. The WHO South-East Asia Region, which accounted for 45% of new TB patients and 50% of deaths globally in 2021, is pivotal to the global fight against TB. "Accelerate Efforts to End TB" by 2030 was adopted as a South-East Asia Regional Flagship Priority (RFP) in 2017. This article illustrates intensified and transformed approaches to address the disease burden following the adoption of RFP and new challenges that emerged during the COVID-19 pandemic. TB case notifications improved by 25% and treatment success rates improved by 6% between 2016 and 2019 due to interventions ranging from galvanising political commitments to empowering and engaging communities. Cumulative TB programme budget allocations in 2022 reached US$ 1.4 billion, about two and a half times the budget in 2016. An ambitious Regional Strategic Plan towards ending TB, 2021-2025, identifies priority interventions that will need investments of up to US$ 3 billion a year to fully implement them. Moving forward, countries in the Region need to leverage RFP and take up intensified, people-centred, holistic interventions for prevention, diagnosis, treatment and care of TB with commensurate investments and cross-ministerial and multi-sectoral coordination.

Estimating the Burden of Tuberculosis in India: A Modelling Study.

Background: Measurements TB incidence and mortality are crucial for monitoring progress towards SDG goals for TB. Until recently, WHO estimated TB burden in India with applied simple, transparent equilibrium models to data from Gujarat, an Indian state where the first state-level prevalence survey was conducted in 2011. However, since then there has been several interventions in India including national TB prevalence survey, infection survey, sub-national survey & certification which gives opportunity for national and sub-national estimates for TB incidence and mortality. Methods: We developed a model is a compartmental, deterministic framework, taking account of TB natural history, as well as India's healthcare system including health care seeking from public and private sector. To address changes in TB burden owing to COVID disruptions, we followed same model that used by WHO in the global TB Report 2022 with additional impact of delta wave in 2021. Major sources of data included National TB Prevalence survey, trends in caseloads in public and private sector including their contribution and mortality information. Results: We estimated total TB incidence of 2.77 million in the year 2022 as against 2.97 in the year 2015 and corresponding TB mortality of 0.32 and 0.36 million respectively. In terms of rate per 1,00,000 TB incidence in 2022 was 196 as compared to 225 in the year 2015 and mortality was 23 and 27 respectively. TB incidence estimates are similar to what was estimated by WHO, while mortality estimates appear different in our estimates due to different calibration targets depending on in-country published data. Conclusion: Even if TB burden is infeasible to measure directly, a range of data can nonetheless offer indirect evidence for its estimation: mathematical modelling can be a helpful tool for bringing together these diverse sources of evidence, and deriving estimates that are consistent with them all. While the RGI reported mortality is an important source of information, its quality and coverage for medically certified cause of deaths requires improvement in India.

Utilization of DNA and 2D metal oxide interaction for an optical biosensor.

The efficient monitoring and early detection of viruses may provide essential information about diseases. In this work, we have highlighted the interaction between DNA and a two-dimensional (2D) metal oxide for developing biosensors for further detection of viral infections. Spectroscopic measurements have been used to probe the efficient interactions between single-stranded DNA (ssDNA) and the 2D metal oxide and make them ideal candidates for detecting viral infections. We have also used fully atomistic molecular dynamics (MD) simulation to give a microscopic understanding of the experimentally observed ssDNA-metal oxide interaction. The adsorption of ssDNA on the inorganic surface was found to be driven by favourable enthalpy change, and 5'-guanine was identified as the interacting nucleotide base. Additionally, the in silico assessment of the conformational changes of the ssDNA chain during the adsorption process was also performed in a quantitative manner. Finally, we comment on the practical implications of these developments for sensing that could help design advanced systems for preventing virus-related pandemics.

As(III) removal from aqueous solutions using simultaneous oxidation and adsorption process by hierarchically magnetic flower-like Fe3O4@C-dot@MnO2 nanocomposite.

In the present study, a magnetic flower-like Fe3O4@C-dot@MnO2 nanocomposite was synthesized by hydrothermal method and applied for As(III) removal by oxidation and adsorption process. Individual property of the entire material (i.e. magnetic property of Fe3O4, mesoporous surface property of C-dot and oxidation property of MnO2) make the composite efficient with good adsorption capacity for As(III) adsorption. The Fe3O4@C-dot@MnO2 nanocomposite had a saturation magnetization of 26.37 emu/g and it magnetically separated within 40 s. The Fe3O4@C-dot@MnO2 nanocomposite was able to reduce the 0.5 mg/L concentration of As(III) to 0.001 mg/L in just 150 min at pH 3. Pseudo-second-order kinetic and Langmuir isotherm model agreed with experimental data. The uptake capacity of Fe3O4@C-dot@MnO2 nanocomposite was 42.68 mg/g. The anions like chloride, sulphate and nitrate did not show any effect on removal but carbonate and phosphate influenced the As(III) removal rate. Regeneration was studied with NaOH and NaClO solution and the adsorbent was used for repeated five cycles above 80% removal capacity. The XPS studies proposed that As(III) first oxidized to As(V) then adsorb on the composite surface. This study shows the potential applicability of Fe3O4@C-dot@MnO2 nanocomposite to high extent and gives a suitable path for the proficient removal of As(III) from wastewater.

Assessment of the recycling potential of valuable metals by mapping the elemental composition in discarded light-emitting diodes (LEDs).

Electronic waste (e-waste) is the world's fastest-growing type of waste, with lighting accounting for 9% of the total. Light-emitting diodes (LEDs) are composed of the most concentrated critical elements (Ag and Au) and recovery of these metals could generate economic benefits and reduce the burdens of environmental pollution; nevertheless, the absence of information about their composition currently presents a challenge in recycling these metals with minimal prospects for recovery. This study assessed the distribution and variation of elemental concentrations of 16 different elements in three generations of LEDs (12 different LED units): sub-mounted-device (SMD #10), chip-on-board (COB #1), and positive-intrinsic-negative (PIN #1). The SMD LEDs contained a considerable amount of Au with a median average concentration of 1204 mg/kg (ranging from 323 - 3687 mg/kg), which was similar to that of COB (1550 mg/kg), but higher than that of PIN LED (175 mg/kg). Based on the total threshold limiting concentration (TTLC), the Cu levels (605,823 mg/kg) in the SMD package exceeded the regulatory limits (2500 mg/kg). Concentrations of the hazardous elements Cr (29 mg/kg), Pb (12 mg/kg), Cd (0.1 mg/kg), and As (1 mg/kg) in the LED packages were within the regulatory limits. To recycle precious metals and other technological metals, a well-organized and dedicated optimized assessment of the value of metals is required especially in accordance with the concept of criticality and recyclability. Two factors, i.e., a high resource index (RI) and technology index (TI), suggest the importance of waste to the economy and has a significant potential for recycling with less processing burdens. Present findings indicated that the COB and a few of the studied SMD LEDs (3020, 4014, 5630, and 7020), exhibit high criticality and recyclability. For the RI and TI index, the contribution of metals such as Cu, Fe, Al, and Au were dominant. These findings can serve as a reference for the development of a viable approach for the recycling and recovery of targeted metals from LED e-waste.

Recent Development Strategies for Bismuth-Driven Materials in Sustainable Energy Systems and Environmental Restoration.

Bismuth(Bi)-based materials have gained considerable attention in recent decades for use in a diverse range of sustainable energy and environmental applications due to their low toxicity and eco-friendliness. Bi materials are widely employed in electrochemical energy storage and conversion devices, exhibiting excellent catalytic and non-catalytic performance, as well as CO2 /N2 reduction and water treatment systems. A variety of Bi materials, including its oxides, chalcogenides, oxyhalides, bismuthates, and other composites, have been developed for understanding their physicochemical properties. In this review, a comprehensive overview of the properties of individual Bi material systems and their use in a range of applications is provided. This review highlights the implementation of novel strategies to modify Bi materials based on morphological and facet control, doping/defect inclusion, and composite/heterojunction formation. The factors affecting the development of different classes of Bi materials and how their control differs between individual Bi compounds are also described. In particular, the development process for these material systems, their mass production, and related challenges are considered. Thus, the key components in Bi compounds are compared in terms of their properties, design, and applications. Finally, the future potential and challenges associated with Bi complexes are presented as a pathway for new innovations.

'Imperfect but useful': pandemic response in the Global South can benefit from greater use of mathematical modelling.

Mathematical modelling has been a helpful resource for planning public health responses to COVID-19. However, there is a need to improve the accessibility of models built within country contexts in the Global South. Immediately following the overwhelming 'second wave' of COVID-19 in India, we developed a user-friendly, web-based modelling simulator in partnership with the public health experts and health administrators for subnational planning. The purpose was to help policy-makers and programme officials at the state and district levels, to construct model-based scenarios for a possible third wave. Here, we describe our experiences of developing and deploying the simulator and propose the following recommendations for future such initiatives: early preparation will be the key for pandemic management planning, including establishment of networks with potential simulator users. Ideally, this preparedness should be conducted during 'peace time', and coordinated by agencies such as WHO. Second, flexible modelling frameworks will be needed, to respond rapidly to future emergencies as the precise nature of any pandemic is impossible to predict. Modelling resources will, therefore, need to be rapidly adaptable to respond as soon as a novel pathogen emerges. Third, limitations of modelling must be communicated clearly and consistently to end users. Finally, systematic mechanisms are required for monitoring the use of models in decision making, which will help in providing modelling support to those local authorities who may benefit most from it. Overall, these lessons from India can be relevant for other countries in the South-Asian-Region, to incorporate modelling resources into their pandemic preparedness planning.

Association between ambient air pollutants and meteorological factors with SARS-CoV-2 transmission and mortality in India: an exploratory study.

BACKGROUND: The Coronavirus disease 2019 (COVID-19) pandemic poses a serious public health concern worldwide. Certain regions of the globe were severely affected in terms of prevalence and mortality than other. Although the cause for this pattern is not clearly understood, lessons learned from previous epidemics and emerging evidences suggest the major role of ecological factors like ambient air pollutants (AAP) and meteorological parameters in increased COVID-19 incidence. The present study aimed to understand the impact of these factors on SARS-CoV-2 transmission and their associated mortality in major cities of India. METHODS: This study used secondary AAP, meteorological and COVID-19 data from official websites for the period January-November 2020, which were divided into Pre-lockdown (January-March 2020), Phase I (April to June 2020) and Phase II (July to November 2020) in India. After comprehensive screening, five major cities that includes 48 CPCB monitoring stations collecting daily data of ambient temperature, particulate matter PM2.5 and 10 were analysed. Spearman and Kendall's rank correlation test was performed to understand the association between SARS-CoV-2 transmission and AAP and, meteorological variables. Similarly, case fatality rate (CFR) was determined to compute the correlation between AAP and COVID-19 related morality. RESULTS: The level of air pollutants in major cities were significantly reduced during Phase I compared to Pre-lock down and increased upon Phase II in all the cities. During the Phase II in Delhi, the strong significant positive correlation was observed between the AAP and SARS-CoV-2 transmission. However, in Bengaluru, Hyderabad, Kolkata and Mumbai AAP levels were moderate and no correlation was noticed. The relation between AT and SARS-CoV-2 transmission was inconclusive as both positive and negative correlation observed. In addition, Delhi and Kolkata showed a positive association between long-term exposure to the AAP and COVID-19 CFR. CONCLUSION: Our findings support the hypothesis that the particulate matter upon exceeding the satisfactory level serves as an important cofactor in increasing the risk of SARS-CoV-2 transmission and related mortality. These findings would help public health experts to understand the SARS-CoV-2 transmission against ecological variables in India and provides supporting evidence to healthcare policymakers and government agencies for formulating strategies to combat the COVID-19.

Plausibility of a third wave of COVID-19 in India: A mathematical modelling based analysis.

BACKGROUND & OBJECTIVES: In the context of India's ongoing resurgence of COVID-19 (second wave since mid-February 2021, following the subsiding of the first wave in September 2020), there has been increasing speculation on the possibility of a future third wave of infection, posing a burden on the healthcare system. Using simple mathematical models of the transmission dynamics of SARS-CoV-2, this study examined the conditions under which a serious third wave could occur. METHODS: Using a deterministic, compartmental model of SARS-CoV-2 transmission, four potential mechanisms for a third wave were examined: (i) waning immunity restores previously exposed individuals to a susceptible state, (ii) emergence of a new viral variant that is capable of escaping immunity to previously circulating strains, (iii) emergence of a new viral variant that is more transmissible than the previously circulating strains, and (iv) release of current lockdowns affording fresh opportunities for transmission. RESULTS: Immune-mediated mechanisms (waning immunity, or viral evolution for immune escape) are unlikely to drive a severe third wave if acting on their own, unless such mechanisms lead to a complete loss of protection among those previously exposed. Likewise, a new, more transmissible variant would have to exceed a high threshold (R0>4.5) to cause a third wave on its own. However, plausible mechanisms for a third wave include: (i) a new variant that is more transmissible and at the same time capable of escaping prior immunity, and (ii) lockdowns that are highly effective in limiting transmission and subsequently released. In both cases, any third wave seems unlikely to be as severe as the second wave. Rapid scale-up of vaccination efforts could play an important role in mitigating these and future waves of the disease. INTERPRETATION & CONCLUSIONS: This study demonstrates plausible mechanisms by which a substantial third wave could occur, while also illustrating that it is unlikely for any such resurgence to be as large as the second wave. Model projections are, however, subject to several uncertainties, and it remains important to scale up vaccination coverage to mitigate against any eventuality. Preparedness planning for any potential future wave will benefit by drawing upon the projected numbers based on the present modelling exercise.

India's pragmatic vaccination strategy against COVID-19: a mathematical modelling-based analysis.

OBJECTIVES: To investigate the impact of targeted vaccination strategies on morbidity and mortality due to COVID-19, as well as on the incidence of SARS-CoV-2, in India. DESIGN: Mathematical modelling. SETTINGS: Indian epidemic of COVID-19 and vulnerable population. DATA SOURCES: Country-specific and age-segregated pattern of social contact, case fatality rate and demographic data obtained from peer-reviewed literature and public domain. MODEL: An age-structured dynamical model describing SARS-CoV-2 transmission in India incorporating uncertainty in natural history parameters was constructed. INTERVENTIONS: Comparison of different vaccine strategies by targeting priority groups such as keyworkers including healthcare professionals, individuals with comorbidities (24-60 years old) and all above 60. MAIN OUTCOME MEASURES: Incidence reduction and averted deaths in different scenarios, assuming that the current restrictions are fully lifted as vaccination is implemented. RESULTS: The priority groups together account for about 18% of India's population. An infection-preventing vaccine with 60% efficacy covering all these groups would reduce peak symptomatic incidence by 20.6% (95% uncertainty intervals (UI) 16.7-25.4) and cumulative mortality by 29.7% (95% CrI 25.8-33.8). A similar vaccine with ability to prevent symptoms (but not infection) will reduce peak incidence of symptomatic cases by 10.4% (95% CrI 8.4-13.0) and cumulative mortality by 32.9% (95% CrI 28.6-37.3). In the event of insufficient vaccine supply to cover all priority groups, model projections suggest that after keyworkers, vaccine strategy should prioritise all who are >60 and subsequently individuals with comorbidities. In settings with weakest transmission, such as sparsely populated rural areas, those with comorbidities should be prioritised after keyworkers. CONCLUSIONS: An appropriately targeted vaccination strategy would witness substantial mitigation of impact of COVID-19 in a country like India with wide heterogeneity. 'Smart vaccination', based on public health considerations, rather than mass vaccination, appears prudent.

1D/2D constructed Bi2S3/Bi2O2CO3 direct Z-Scheme heterojunction: A versatile photocatalytic material for boosted photodegradation, photoreduction and photoelectrochemical detection of water-based contaminants.

In this work, two-dimensional Bi2O2CO3 disk is synthesized, followed by the growth of Bi2S3 over Bi2O2CO3 via topotactic transformation by controlling the amount of thiourea under hydrothermal conditions. The synthesized composite catalyst is investigated for photocatalytic oxidation and reduction of tetracycline hydrochloride and hexavalent chromium under visible light irradiation. High interfacial contact between the Bi2O2CO3 disk0 and Bi2S3 fiber is confirmed via high-resolution microscopic imaging. Enhanced light absorption and increased charge carrier separation is observed after the formation of the Bi2S3/Bi2O2CO3 composite. The Bi2S3/Bi2O2CO3 composite grown using 1 mmol of thiourea shows approximately 98% degradation of tetracycline hydrochloride after 120 min and 99% Cr(VI) reduction after 90 min of photochemical reaction under visible light irradiation. The charge separation is due to the formed internal electric field at the interface, which upon light irradiation follows a z-scheme charge transfer hindering the recombination at the Bi2S3 and Bi2O2CO3 interface, thereby contributing efficiently to the photochemical process. In addition, the mechanism of the photochemical reaction for the degradation of pollutants is supported using quencher and probe experiments. Furthermore, photoelectrochemical detection of antibiotic in aqueous solution is conducted to understand the sensing feasibility of the synthesized system.

Combining serology with case-detection, to allow the easing of restrictions against SARS-CoV-2: a modelling-based study in India.

India's lockdown and subsequent restrictions against SARS-CoV-2, if lifted without any other mitigations in place, could risk a second wave of infection. A test-and-isolate strategy, using PCR diagnostic tests, could help to minimise the impact of this second wave. Meanwhile, population-level serological surveillance can provide valuable insights into the level of immunity in the population. Using a mathematical model, consistent with an Indian megacity, we examined how seroprevalence data could guide a test-and-isolate strategy, for fully lifting restrictions. For example, if seroprevalence is 20% of the population, we show that a testing strategy needs to identify symptomatic cases within 5-8 days of symptom onset, in order to prevent a resurgent wave from overwhelming hospital capacity in the city. This estimate is robust to uncertainty in the effectiveness of the lockdown, as well as in immune protection against reinfection. To set these results in their economic context, we estimate that the weekly cost of such a PCR-based testing programme would be less than 2.1% of the weekly economic loss due to the lockdown. Our results illustrate how PCR-based testing and serological surveillance can be combined to design evidence-based policies, for lifting lockdowns in Indian cities and elsewhere.

The potential impact of preventive therapy against tuberculosis in the WHO South-East Asian Region: a modelling approach.

BACKGROUND: The prevention of tuberculosis (TB) is key for accelerating current, slow declines in TB burden. The 2018 World Health Organization (WHO) guidelines on eligibility for preventive therapy to treat latent TB infection (LTBI) include people living with human immunodeficiency virus (PLHIV), household contacts of TB patients including children, and those with clinical conditions including silicosis, dialysis, transplantation, etc. and other country-specific groups. We aimed to estimate the potential impact of full implementation of these guidelines in the WHO South-East Asian (SEA) Region, which bears the largest burden of TB and LTBI amongst the WHO regions. METHODS: We developed mathematical models of TB transmission dynamics, calibrated individually to each of the 11 countries in the region. We modelled preventive therapy in the absence of other TB interventions. As an alternative comparator, reflecting ongoing developments in TB control in the region, we also simulated improvements in the treatment cascade for active TB, including private sector engagement and intensified case-finding. Relative to both scenarios, for each country in the region, we projected TB cases and deaths averted between 2020 and 2030, by full uptake of preventive therapy, defined as comprehensive coverage amongst eligible populations as per WHO guidelines, and assuming outcomes consistent with clinical trials. We also performed sensitivity analysis to illustrate impact under less-than-optimal conditions. RESULTS: At the regional level, full uptake of preventive therapy amongst identified risk groups would reduce annual incidence rates in 2030 by 8.30% (95% CrI 6.48-10.83) relative to 2015, in the absence of any additional interventions. If implemented against a backdrop of improved TB treatment cascades, preventive therapy would achieve an incremental 6.93 percentage points (95% CrI 5.81-8.51) of reduction in annual incidence rates, compared to 2015. At the regional level, the numbers of individuals with latent TB infection that need to be treated to avert 1 TB case is 64 (95% CrI 55-74). Sensitivity analysis illustrates that results for impact are roughly proportional to 'effective coverage' (the product of actual coverage and effectiveness of the regimen). CONCLUSIONS: Full implementation of WHO guidelines is important for ending TB in the SEA Region. Although future strategies will need to be expanded to the population level, to achieve large declines in TB incidence, the uptake of current tools can offer a valuable step in this direction.

Prudent public health intervention strategies to control the coronavirus disease 2019 transmission in India: A mathematical model-based approach.

Background & objectives: Coronavirus disease 2019 (COVID-19) has raised urgent questions about containment and mitigation, particularly in countries where the virus has not yet established human-to-human transmission. The objectives of this study were to find out if it was possible to prevent, or delay, the local outbreaks of COVID-19 through restrictions on travel from abroad and if the virus has already established in-country transmission, to what extent would its impact be mitigated through quarantine of symptomatic patients? Methods: These questions were addressed in the context of India, using simple mathematical models of infectious disease transmission. While there remained important uncertainties in the natural history of COVID-19, using hypothetical epidemic curves, some key findings were illustrated that appeared insensitive to model assumptions, as well as highlighting critical data gaps. Results: It was assumed that symptomatic quarantine would identify and quarantine 50 per cent of symptomatic individuals within three days of developing symptoms. In an optimistic scenario of the basic reproduction number (R0) being 1.5, and asymptomatic infections lacking any infectiousness, such measures would reduce the cumulative incidence by 62 per cent. In the pessimistic scenario of R0=4, and asymptomatic infections being half as infectious as symptomatic, this projected impact falls to two per cent. Interpretation & conclusions: Port-of-entry-based entry screening of travellers with suggestive clinical features and from COVID-19-affected countries, would achieve modest delays in the introduction of the virus into the community. Acting alone, however, such measures would be insufficient to delay the outbreak by weeks or longer. Once the virus establishes transmission within the community, quarantine of symptomatics may have a meaningful impact on disease burden. Model projections are subject to substantial uncertainty and can be further refined as more is understood about the natural history of infection of this novel virus. As a public health measure, health system and community preparedness would be critical to control any impending spread of COVID-19 in the country.

Insights into the rheology of cohesive granular media.

Characterization and prediction of the "flowability" of powders are of paramount importance in many industries. However, our understanding of the flow of powders like cement or flour is sparse compared to the flow of coarse, granular media like sand. The main difficulty arises because of the presence of adhesive forces between the grains, preventing smooth and continuous flows. Several tests are used in industrial contexts to probe and quantify the "flowability" of powders. However, they remain empirical and would benefit from a detailed study of the physics controlling flow dynamics. Here, we attempt to fill the gap by performing intensive discrete numerical simulations of cohesive grains flowing down an inclined plane. We show that, contrary to what is commonly perceived, the cohesive nature of the flow is not entirely controlled by the interparticle adhesion, but that stiffness and inelasticity of the grains also play a significant role. For the same adhesion, stiffer and less dissipative grains yield a less cohesive flow. This observation is rationalized by introducing the concept of a dynamic, "effective" adhesive force, a single parameter, which combines the effects of adhesion, elasticity, and dissipation. Based on this concept, a rheological description of the flow is proposed for the cohesive grains. Our results elucidate the physics controlling the flow of cohesive granular materials, which may help in designing new approaches to characterize the "flowability" of powders.

Viscosity modification enhanced the migration and distribution of colloidal Mg(OH)2 in aquifers contaminated by heavy metals.

Mg(OH)2 is extensively considered as an potential material for groundwater remediation because its injection could provide a long-term pH buffering system. In this study, colloidal Mg(OH)2 was regarded as an alternative reagent for the in-situ remediation of heavy metal polluted groundwater. However, experiments demonstrated that the transport performance of colloidal Mg(OH)2 in groundwater was depressed by the contamination of heavy metals and its stabilization performance for heavy metals was deteriorated. To solve these difficulties, the transport properties of colloidal Mg(OH)2 was enhanced by viscosity modification by adding xanthan gum (XG). Column tests were conducted to investigate the transport performance of colloidal Mg(OH)2 with and without viscosity modification, and to evaluate its stabilization effect for Pb and Cd polluted aquifer. Experimental results indicate that although the injection pressure increased during the migration of colloidal Mg(OH)2, the increased viscosity effectively could decrease the intensity of Brownian motion of Mg(OH)2 particles and reduce the collision efficiency between colloidal particles and aquifer media. Thus, deposition of Mg(OH)2 particles on aquifer media significantly reduced after viscosity modification, and its migration performance in groundwater was effectively enhanced. In contrast, the distribution of colloidal Mg(OH)2 was more uniform after viscosity modification, and immobilization of heavy metals in contaminated aquifer was noticeably improved, furthermore the exchangeable fraction of Pb and Cd is significantly reduced.