Census-independent population estimation using representation learning.

Knowledge of population distribution is critical for building infrastructure, distributing resources, and monitoring the progress of sustainable development goals. Although censuses can provide this information, they are typically conducted every 10 years with some countries having forgone the process for several decades. Population can change in the intercensal period due to rapid migration, development, urbanisation, natural disasters, and conflicts. Census-independent population estimation approaches using alternative data sources, such as satellite imagery, have shown promise in providing frequent and reliable population estimates locally. Existing approaches, however, require significant human supervision, for example annotating buildings and accessing various public datasets, and therefore, are not easily reproducible. We explore recent representation learning approaches, and assess the transferability of representations to population estimation in Mozambique. Using representation learning reduces required human supervision, since features are extracted automatically, making the process of population estimation more sustainable and likely to be transferable to other regions or countries. We compare the resulting population estimates to existing population products from GRID3, Facebook (HRSL) and WorldPop. We observe that our approach matches the most accurate of these maps, and is interpretable in the sense that it recognises built-up areas to be an informative indicator of population.

Routine Vaccination Coverage - Worldwide, 2020.

Endorsed by the World Health Assembly in 2020, the Immunization Agenda 2030 (IA2030) strives to reduce morbidity and mortality from vaccine-preventable diseases across the life course (1). This report, which updates a previous report (2), presents global, regional,* and national vaccination coverage estimates and trends as of 2020. Changes are described in vaccination coverage and the numbers of unvaccinated and undervaccinated children as measured by receipt of the first and third doses of diphtheria, tetanus, and pertussis-containing vaccine (DTP) in 2020, when the COVID-19 pandemic began, compared with 2019. Global estimates of coverage with the third dose of DTP (DTP3) and a polio vaccine (Pol3) decreased from 86% in 2019 to 83% in 2020. Similarly, coverage with the first dose of measles-containing vaccine (MCV1) dropped from 86% in 2019 to 84% in 2020. The last year that coverage estimates were at 2020 levels was 2009 for DTP3 and 2014 for both MCV1 and Pol3. Worldwide, 22.7 million children (17% of the target population) were not vaccinated with DTP3 in 2020 compared with 19.0 million (14%) in 2019. Children who did not receive the first DTP dose (DTP1) by age 12 months (zero-dose children) accounted for 95% of the increased number. Among those who did not receive DTP3 in 2020, approximately 17.1 million (75%) were zero-dose children. Global coverage decreased in 2020 compared with 2019 estimates for the completed series of Haemophilus influenzae type b (Hib), hepatitis B vaccine (HepB), human papillomavirus vaccine (HPV), and rubella-containing vaccine (RCV). Full recovery from COVID-19-associated disruptions will require targeted, context-specific strategies to identify and catch up zero-dose and undervaccinated children, introduce interventions to minimize missed vaccinations, monitor coverage, and respond to program setbacks (3).

SELECTION OF PFCRT 76T AND PFMDR1 86Y MUTANT PLASMODIUM FALCIPARUM AFTER TREATMENT OF UNCOMPLICATED MALARIA WITH ARTESUNATE-AMODIAQUINE IN REPUBLIC OF GUINEA.

The use of Amodiaquine monotherapy is associated with the selection of molecular markers of Plasmodium falciparum resistance to chloroquine (pfcrt and pfmdr1). The decrease in sensitivity and the emergence of P. falciparum resistant to artemisinin-based combination therapy have been reported. Therefore, it is important to assess the impact of treatment of uncomplicated malaria with Artesunate-Amodiaquine (AS+AQ) on molecular markers of antimalarial resistance. We used standard World Health Organization (WHO) protocols to determine the in vivo efficacy of the combination (AS+AQ). In total, 170 subjects were included in the study. The molecular analysis focused on 168 dried blood spots. The aims were to determine the frequency of pfcrt 76T and pfmdr1 86Y mutations and the rates of reinfection using polymorphism markers msp1, msp2, and microsatellite markers (CA1, Ta87, TA99). Nested-PCR was used, followed in some cases by a restriction digestion. The level of P. falciparum clinical response was 92.9% (156/168) of Adequate Clinical and Parasitological Response (ACPR) before molecular correction and 97.0% (163/168) after molecular correction (P = 0.089). The frequency of mutation point pfcrt 76T was 76.2% (128/168) before treatment and 100% (7/7) after treatment (P = 0.1423). For the pfmdr1 mutation, the frequency was 28% (47/168) before treatment and 60% (6/10) after treatment (P = 0.1124). The rate of pfcrt 76T + pfmdr1 86Y was 22% (37/168) before and 50% (6/12) after treatment (P = 0.1465). Despite the presence of AS in the combination, AS+AQ selects for pfcrt 76T and pfmdr1 86Y mutant P. falciparum in Guinea.

Every Child on the Map: A Theory of Change Framework for Improving Childhood Immunization Coverage and Equity Using Geospatial Data and Technologies.

The effective use of geospatial data and technologies to collect, manage, analyze, model, and visualize geographic data has great potential to improve data-driven decision-making for immunization programs. This article presents a theory of change for the use of geospatial technologies for immunization programming-a framework to illustrate the ways in which geospatial data and technologies can contribute to improved immunization outcomes and have a positive impact on childhood immunization coverage rates in low- and middle-income countries. The theory of change is the result of a review of the state of the evidence and literature; consultation with implementers, donors, and immunization and geospatial technology experts; and a review of country-level implementation experiences. The framework illustrates how the effective use of geospatial data and technologies can help immunization programs realize improvements in the number of children immunized by producing reliable estimates of target populations, identifying chronically missed settlements and locations with the highest number of zero-dose and under-immunized children, and guiding immunization managers with solutions to optimize resource distribution and location of health services. Through these direct effects on service delivery, geospatial data and technologies can contribute to the strengthening of the overall health system with equity in immunization coverage. Recent implementation of integrated geospatial data and technologies for the immunization program in Myanmar demonstrate the process that countries may experience on the path to achieving lasting systematic improvements. The theory of change presented here may serve as a guide for country program managers, implementers, donors, and other stakeholders to better understand how geospatial tools can support immunization programs and facilitate integrated service planning and equitable delivery through the unifying role of geography and geospatial data.

Compliance of WHO and UNICEF estimates of national immunization coverage (WUENIC) with Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER) criteria.

Background: The objective of the study was to assess compliance of the WHO and UNICEF estimates of national immunization coverage (WUENIC) against the 18 criteria of the Guidelines for Accurate and Transparent Health Estimates Reporting (GATHER) that define and promote good practice in reporting of global health estimates. Methods: We conducted a desk review of the WUENIC estimation and reporting process vis-à-vis each of the 18 GATHER criteria to complete a self-assessment of compliance with GATHER. Results: Overall, WUENIC estimates are fully compliant with 17 of the GATHER criteria and partially compliant with one criterion-criterion 11, which is related to candidate model evaluation and final model selection. Conclusion: The GATHER criteria provide a useful framework for documenting WUENIC's compliance with contemporary reporting requirements. Given the role of vaccination coverage estimates in global monitoring and guiding disease control efforts, WHO and UNICEF strive to produce and publish robust estimates of vaccination coverage through a transparent process that emphasizes country involvement.

Routine Vaccination Coverage - Worldwide, 2019.

Endorsed by the World Health Assembly in 2020, the Immunization Agenda 2030 strives to reduce morbidity and mortality from vaccine-preventable diseases across the life course (1). This report, which updates previous reports (2), presents global, regional,* and national vaccination coverage estimates and trends as of 2019 and describes the number of surviving infants who did not receive the first dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP1) during the first year of life (i.e., zero-dose children), which serves as a proxy for children with poor access to immunization and other health services. Global estimates of coverage with the third dose of DTP (DTP3), the first dose of measles-containing vaccine (MCV1), and the third dose of polio vaccine (Pol3) ranged from 84% to 86% during 2010-2019. Worldwide, 19.7 million children (15%) were not vaccinated with DTP3 in 2019, 13.8 million (70%) of whom were zero-dose children. During 2010-2019, the number of zero-dose children increased in the African, Americas, and Western Pacific regions. Global coverage with the second MCV dose (MCV2) increased from 42% in 2010 to 71% in 2019. During 2010-2019, global coverage with underused vaccines increased for the completed series of rotavirus vaccine (rota), pneumococcal conjugate vaccine (PCV), rubella-containing vaccine (RCV), Haemophilus influenzae type b vaccine (Hib), hepatitis B vaccine (HepB), and human papillomavirus vaccine (HPV). Achieving universal coverage with all recommended vaccines will require tailored, context-specific strategies to reach communities with substantial proportions of zero-dose and incompletely vaccinated children, particularly those in remote rural, urban poor, and conflict-affected communities (3).

Global Routine Vaccination Coverage, 2018.

Endorsed by the World Health Assembly in 2012, the Global Vaccine Action Plan 2011-2020 (GVAP) (1) calls on all countries to reach ≥90% national coverage with all vaccines in the country's national immunization schedule by 2020. Building on previous analyses (2) and using the World Health Organization (WHO) and United Nations Children's Fund (UNICEF) global vaccination coverage estimates as of 2018, this report presents global, regional, and national vaccination coverage estimates and trends, including vaccination dropout rates. According to these estimates, global coverage with the first dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP1) remained relatively unchanged from 2010 (89%) to 2018 (90%). Global coverage with the third DTP dose (DTP3) followed a similar global trend to that of DTP1, remaining relatively consistent from 2010 (84%) to 2018 (86%) (3). Globally, 19.4 million children (14%) were not fully vaccinated in 2018, and among them, 13.5 million (70%) did not receive any DTP doses. Overall, dropout rates from DTP1 to DTP3 decreased globally from 6% in 2010 to 4% in 2018. Global coverage with the first dose of measles-containing vaccine (MCV1) remained between 84% and 86% during 2010-2018. Among countries that offer a second MCV dose (MCV2) during the second year of life, coverage increased from 19% in 2007 to 54% in 2018; among countries offering MCV2 to older age groups (children aged 3-14 years), coverage also increased, from 36% in 2007 to 69% in 2018 (3). Globally, the estimated difference in coverage with MCV1 and MCV2 in 2018 was 17%. However, among new and underused vaccines, global coverage increased from 2007 to 2018 for completed series of rotavirus vaccine, pneumococcal conjugate vaccine (PCV), rubella vaccine, Haemophilus influenzae type b vaccine (Hib), and hepatitis B vaccine (HepB). To reach global vaccination coverage goals for vaccines recommended during childhood, adolescence, and adulthood, tailored strategies that address local determinants for incomplete vaccination are needed, including targeting hard-to-reach and hard-to-vaccinate populations.

Global Routine Vaccination Coverage - 2017.

Endorsed by the World Health Assembly in 2012, the Global Vaccine Action Plan 2011-2020 (GVAP) (1) calls on all countries to reach ≥90% national coverage with all vaccines in the country's national immunization schedule by 2020. This report updates previous reports (2,3) and presents global, regional, and national vaccination coverage estimates and trends as of 2017. It also describes the number of infants surviving to age 1 year (surviving infants) who did not receive the third dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP3), a key indicator of immunization program performance (4,5), with a focus on the countries with the highest number of children who did not receive DTP3 in 2017. Based on the World Health Organization (WHO) and United Nations Children's Fund (UNICEF) estimates, global DTP3 coverage increased from 79% in 2007 to 84% in 2010, and has remained stable from 2010 to 2017 (84% to 85%). In 2017, among the 19.9 million children who did not receive DTP3 in the first year of life, 62% (12.4 million) lived in 10 countries. From 2007 to 2017, the number of children who had not received DTP3 decreased in five of these 10 countries and remained stable or increased in the other five. Similar to DTP3 coverage, global coverage with the first measles-containing vaccine dose (MCV1) increased from 80% in 2007 to 84% in 2010, and has remained stable from 2010 to 2017 (84% to 85%). Coverage with the third dose of polio vaccine (Pol3) has remained stable at 84%-85% since 2010. From 2007 to 2017, estimated global coverage with the second MCV dose (MCV2) increased from 33% to 67%, as did coverage with the completed series of rotavirus (2% to 28%), pneumococcal conjugate (PCV) (4% to 44%), rubella (26% to 52%), Haemophilus influenzae type b (Hib) (25% to 72%) and hepatitis B (HepB) (birth dose: 24% to 43%; 3-dose series: 63% to 84%) vaccines. Targeted, context-specific strategies are needed to reach and sustain high vaccination coverage, particularly in countries with the highest number of unvaccinated children.

A Facile and Scalable Route to the Preparation of Catalytic Membranes with in Situ Synthesized Supramolecular Dendrimer Particle Hosts for Pt(0) Nanoparticles Using a Low-Generation PAMAM Dendrimer (G1-NH2) as Precursor.

Since the first reports of Cu dendrimer-encapsulated nanoparticles (DENs) published in 1998, the dendrimer-templating method has become the best and most versatile method for preparing ultrafine metallic and bimetallic nanoparticles (1-3 nm) with well-defined compositions, high catalytic activity, and tunable selectivity. However, DENs have remained for the most part model systems with limited prospects for scale up and integration into high-performance and reusable catalytic modules and systems for industrial-scale applications. Here, we describe a facile and scalable route to the preparation of catalytic polyvinylidene fluoride (PVDF) membranes with in situ synthesized supramolecular dendrimer particles (SDPs) that can serve as hosts and containers for Pt(0) nanoparticles (2-3 nm). These new catalytic membranes were prepared using a reactive encapsulation process similar to that utilized to prepare Pt DENs by addition of a reducing agent (sodium borohydride) to aqueous complexes of Pt(II) + G4-OH/G6-OH polyamidoamine (PAMAM) dendrimers. However, the SDPs (2.4 µm average diameter) of our new mixed matrix PVDF-PAMAM membranes were synthesized in the dope dispersion without purification prior to film casting using (i) a low-generation PAMAM dendrimer (G1-NH2) as particle precursor and (ii) epichlorohydrin, an inexpensive functional reagent, as cross-linker. In addition, the membrane PAMAM particles contain secondary amine groups (∼1.9 mequiv per gram of dry membrane), which are more basic and thus have higher Pt binding affinity than the tertiary amine groups of the G4-OH and G6-OH PAMAM dendrimers. Proof-of-concept experiments show that our new PVDF-PAMAM-G1-Pt/membranes can serve as highly active and reusable catalysts for the hydrogenation of alkenes and alkynes to the corresponding alkanes using (i) H2 at room temperature and a pressure of 1 bar and (ii) low catalyst loadings of ∼1.4-1.6 mg of Pt. Using cyclohexene as model substrate, we observed near quantitative conversion to cyclohexane (∼98%). The regeneration studies showed that our new Pt/membrane catalysts are stable and can be reused for five consecutive reaction cycles for a total duration of 120 h including 60 h of heating at 100 °C under vacuum for substrate, product, and solvent removal with no detectable loss of cyclohexene hydrogenation activity. The overall results of our study point to a promising, versatile, and scalable path for the integration of catalytic membranes with in situ synthesized SDP hosts for Pt(0) nanoparticles into high-throughput modules and systems for heterogeneous catalytic hydrogenations, an important class of reactions that are widely utilized in industry to produce pharmaceuticals, agrochemicals, and specialty chemicals.

Global Routine Vaccination Coverage, 2016.

The Global Vaccine Action Plan 2011-2020 (GVAP) (1), endorsed by the World Health Assembly in 2012, calls on all countries to reach ≥90% national coverage for all vaccines in the country's routine immunization schedule by 2020. CDC and the World Health Organization (WHO) evaluated the WHO and United Nations Children's Fund (UNICEF) global vaccination coverage estimates to describe changes in global and regional coverage as of 2016. Global coverage estimates for the third dose of diphtheria and tetanus toxoids and pertussis-containing vaccine (DTP3), the third dose of polio vaccine, and the first dose of measles-containing vaccine (MCV1) have ranged from 84% to 86% since 2010. The dropout rate (the proportion of children who started but did not complete a vaccination series), an indicator of immunization program performance, was estimated to be 5% in 2016 for the 3-dose DTP series, with dropout highest in the African Region (11%) and lowest in the Western Pacific Region (0.4%). During 2010-2016, estimated global coverage with the second MCV dose (MCV2) increased from 21% to 46% by the end of the second year of life and from 39% to 64% when older age groups (3-14 years) were included (2). Improvements in national immunization program performance are necessary to reach and sustain high vaccination coverage to increase protection from vaccine-preventable diseases for all persons.

Global Routine Vaccination Coverage, 2015.

In 1974, the World Health Organization (WHO) established the Expanded Program on Immunization* to provide protection against six vaccine-preventable diseases through routine infant immunization (1). Based on 2015 WHO and United Nations Children's Fund (UNICEF) estimates, global coverage with the third dose of diphtheria-tetanus-pertussis vaccine (DTP3), the first dose of measles-containing vaccine (MCV1) and the third dose of polio vaccine (Pol3) has remained stable (84%-86%) since 2010. From 2014 to 2015, estimated global coverage with the second MCV dose (MCV2) increased from 39% to 43% by the end of the second year of life and from 58% to 61% when older age groups were included. Global coverage was higher in 2015 than 2010 for newer or underused vaccines, including rotavirus vaccine, pneumococcal conjugate vaccine (PCV), rubella vaccine, Haemophilus influenzae type b (Hib) vaccine, and 3 doses of hepatitis B (HepB3) vaccine. Coverage estimates varied widely by WHO Region, country, and district; in addition, for the vaccines evaluated (MCV, DTP3, Pol3, HepB3, Hib3), wide disparities were found in coverage by country income classification. Improvements in equity of access are necessary to reach and sustain higher coverage and increase protection from vaccine-preventable diseases for all persons.

Mixed Matrix PVDF Membranes With in Situ Synthesized PAMAM Dendrimer-Like Particles: A New Class of Sorbents for Cu(II) Recovery from Aqueous Solutions by Ultrafiltration.

Advances in industrial ecology, desalination, and resource recovery have established that industrial wastewater, seawater, and brines are important and largely untapped sources of critical metals and elements. A Grand Challenge in metal recovery from industrial wastewater is to design and synthesize high capacity, recyclable and robust chelating ligands with tunable metal ion selectivity that can be efficiently processed into low-energy separation materials and modules. In our efforts to develop high capacity chelating membranes for metal recovery from impaired water, we report a one-pot method for the preparation of a new family of mixed matrix polyvinylidene fluoride (PVDF) membranes with in situ synthesized poly(amidoamine) [PAMAM] particles. The key feature of our new membrane preparation method is the in situ synthesis of PAMAM dendrimer-like particles in the dope solutions prior to membrane casting using low-generation dendrimers (G0 and G1-NH2) with terminal primary amine groups as precursors and epichlorohydrin (ECH) as cross-linker. By using a combined thermally induced phase separation (TIPS) and nonsolvent induced phase separation (NIPS) casting process, we successfully prepared a new family of asymmetric PVDF ultrafiltration membranes with (i) neutral and hydrophilic surface layers of average pore diameters of 22-45 nm, (ii) high loadings (∼48 wt %) of dendrimer-like PAMAM particles with average diameters of ∼1.3-2.4 µm, and (iii) matrices with sponge-like microstructures characteristics of membranes with strong mechanical integrity. Preliminary experiments show that these new mixed matrix PVDF membranes can serve as high capacity sorbents for Cu(II) recovery from aqueous solutions by ultrafiltration.

Mining Critical Metals and Elements from Seawater: Opportunities and Challenges.

The availability and sustainable supply of technology metals and valuable elements is critical to the global economy. There is a growing realization that the development and deployment of the clean energy technologies and sustainable products and manufacturing industries of the 21st century will require large amounts of critical metals and valuable elements including rare-earth elements (REEs), platinum group metals (PGMs), lithium, copper, cobalt, silver, and gold. Advances in industrial ecology, water purification, and resource recovery have established that seawater is an important and largely untapped source of technology metals and valuable elements. This feature article discusses the opportunities and challenges of mining critical metals and elements from seawater. We highlight recent advances and provide an outlook of the future of metal mining and resource recovery from seawater.

Microalgae recovery by ultrafiltration using novel fouling-resistant PVDF membranes with in situ PEGylated polyethyleneimine particles.

In this article, we report the preparation, characterization and microalgae recovery potential of a new family of fouling-resistant polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes embedded with hydrophilic and PEGylated polymeric particles. To optimize membrane performance for microalgae harvesting, we investigate the effects of three hydrophilic additives (Pluronic F-127, polyvinylpyrrolidone and polyethylene glycol) on the morphology, pore size, bulk composition, surface composition, wettability and surface charge, flux and fouling resistance of the mixed matrix PVDF membranes with in situ PEGylated polyethyleneimine (PEI) particles. Our filtration experiments show that a mixed matrix PVDF membrane with PEGylated PEI particles and Pluronic F-127 additive (PNSM-1) has an algae retention of 100% with a permeate flux of 96 L/m(2)/hr that is larger (by ∼50%) than that of a commercial and hydrophilic PVDF UF membrane with a molecular weight cut-off of 30 kDa using a suspension of Chlorella sp. KR-1 microalgae with 1.2-1.4 g/L of dry biomass. The algae and water flux recovery rates of our new PNSM-1 are equal to∼ 94% and 100%, respectively, following a simulated membrane wash with deionized water and two subsequent water and microalgae filtration cycles.

Great apes and biodiversity offset projects in Africa: the case for national offset strategies.

The development and private sectors are increasingly considering "biodiversity offsets" as a strategy to compensate for their negative impacts on biodiversity, including impacts on great apes and their habitats in Africa. In the absence of national offset policies in sub-Saharan Africa, offset design and implementation are guided by company internal standards, lending bank standards or international best practice principles. We examine four projects in Africa that are seeking to compensate for their negative impacts on great ape populations. Our assessment of these projects reveals that not all apply or implement best practices, and that there is little standardization in the methods used to measure losses and gains in species numbers. Even if they were to follow currently accepted best-practice principles, we find that these actions may still fail to contribute to conservation objectives over the long term. We advocate for an alternative approach in which biodiversity offset and compensation projects are designed and implemented as part of a National Offset Strategy that (1) takes into account the cumulative impacts of development in individual countries, (2) identifies priority offset sites, (3) promotes aggregated offsets, and (4) integrates biodiversity offset and compensation projects with national biodiversity conservation objectives. We also propose supplementary principles necessary for biodiversity offsets to contribute to great ape conservation in Africa. Caution should still be exercised, however, with regard to offsets until further field-based evidence of their effectiveness is available.

National Health and Nutrition Examination Survey: National Youth Fitness Survey Estimation Procedures, 2012.

BACKGROUND: The National Health and Nutrition Examination Survey's (NHANES) National Youth Fitness Survey (NNYFS) was conducted in 2012 by the Centers for Disease Control and Prevention's National Center for Health Statistics (NCHS). NNYFS collected data on physical activity and fitness levels to evaluate the health and fitness of children aged 3-15 in the United States. The survey comprised three levels of data collection: a household screening interview (or screener), an in-home personal interview, and a physical examination. The screener's primary objective was to determine whether any children in the household were eligible for the interview and examination. Eligibility was determined by preset selection probabilities for desired sex-age subdomains. After selection, the in-home personal interview collected demographic, health, physical activity, and nutrition information about the child as well as information about the household. The examination included physical measurements and fitness tests. OBJECTIVES: This report provides background on the NNYFS program and summarizes the survey's sample design specifications. The report presents NNYFS estimation procedures, including the methods used to calculate survey weights for the full sample as well as a combined NHANES/NNYFS sample for 2012 (accessible only through the NCHS Research Data Center). The report also describes appropriate variance estimation methods. Documentation of the sample selection methods, survey content, data collection procedures, and methods to assess nonsampling errors are reported elsewhere.

Branched polymeric media: perchlorate-selective resins from hyperbranched polyethyleneimine.

Perchlorate (ClO(4)(-)) is a persistent contaminant found in drinking groundwater sources in the United States. Ion exchange (IX) with selective and disposable resins based on cross-linked styrene divinylbenzene (STY-DVB) beads is currently the most commonly utilized process for removing low concentrations of ClO(4)(-) (10-100 ppb) from contaminated drinking water sources. However, due to the low exchange capacity of perchlorate-selective STY-DVB resins (∼0.5-0.8 eq/L), the overall cost becomes prohibitive when treating groundwater with higher concentration of ClO(4)(-) (e.g., 100-1000 ppb). In this article, we describe a new perchlorate-selective resin with high exchange capacity. This new resin was prepared by alkylation of branched polyethyleneimine (PEI) beads obtained from an inverse suspension polymerization process. Batch and column studies show that our new PEI resin with mixed hexyl/ethyl quaternary ammonium chloride exchange sites can selectively extract trace amounts of ClO(4)(-) from a makeup groundwater (to below detection limit) in the presence of competing ions. In addition, this resin has a strong-base exchange capacity of 1.4 eq/L, which is 1.75-2.33 times larger than those of commercial perchlorate-selective STY-DVB resins. The overall results of our studies suggest that branched PEI beads provide versatile and promising building blocks for the preparation of perchlorate-selective resins with high exchange capacity.

Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine.

Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 ± 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ∼70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-D-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 ± 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ∼70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution.

Interactions of poly(amidoamine) dendrimers with human serum albumin: binding constants and mechanisms.

The interactions of nanomaterials with plasma proteins have a significant impact on their in vivo transport and fate in biological fluids. This article discusses the binding of human serum albumin (HSA) to poly(amidoamine) [PAMAM] dendrimers. We use protein-coated silica particles to measure the HSA binding constants (K(b)) of a homologous series of 19 PAMAM dendrimers in aqueous solutions at physiological pH (7.4) as a function of dendrimer generation, terminal group, and core chemistry. To gain insight into the mechanisms of HSA binding to PAMAM dendrimers, we combined (1)H NMR, saturation transfer difference (STD) NMR, and NMR diffusion ordered spectroscopy (DOSY) of dendrimer-HSA complexes with atomistic molecular dynamics (MD) simulations of dendrimer conformation in aqueous solutions. The binding measurements show that the HSA binding constants (K(b)) of PAMAM dendrimers depend on dendrimer size and terminal group chemistry. The NMR (1)H and DOSY experiments indicate that the interactions between HSA and PAMAM dendrimers are relatively weak. The (1)H NMR STD experiments and MD simulations suggest that the inner shell protons of the dendrimers groups interact more strongly with HSA proteins. These interactions, which are consistently observed for different dendrimer generations (G0-NH(2)vs G4-NH(2)) and terminal groups (G4-NH(2)vs G4-OH with amidoethanol groups), suggest that PAMAM dendrimers adopt backfolded configurations as they form weak complexes with HSA proteins in aqueous solutions at physiological pH (7.4).