A Dual-Mode Near-Infrared Optical and Photoacoustic Imaging Agent Based on a Low Energy Absorbing Ytterbium Complex.

Near-infrared (NIR) luminescence and photoacoustic (PA) imaging have attracted increasing attention for the real-time monitoring of biological samples due to high sensitivity, resolution, and pronounced signal detection depth, respectively. For improved contrast, both techniques require imaging agents possessing high absorption in the red-NIR range. Herein, we took advantage of a ternary complex formed with the anionic ytterbium(III) tetrakis(2-thenoyltrifluoroacetonate) ([Yb(tta)4]-) and the cationic NIR-absorbing chromophore, 1,1'-diethyl-2,2'-dicarbocyanine (Cy+), to evaluate its potential to act as a dual-mode NIR luminescence and PA imaging agent. We demonstrated that, upon excitation with red-NIR light, Cy[Yb(tta)4] encapsulated into polystyrene nanoparticles is able to generate both NIR Yb3+ emission and a PA signal in an imaging experiment performed in a tissue-mimicking phantom.

Standard Versus Custom-Made Acetabular Implants in Revision Total Hip Arthroplasty.

BACKGROUND: Today, various options are used for the reconstruction of acetabular bone loss in revision total hip arthroplasty (RTHA). The aim of the study was to compare the outcomes of using standard acetabular implants (SAIs) and custom-made acetabular implants (CMAIs) in RTHA in cases with extensive acetabular bone loss. METHODS: This was a comparative analysis of the results of 106 operations of RTHA performed during the period from January 2013 to December 2019. In 61 cases (57.5%), CMAIs were used. In 45 cases (42.5%), SAIs were implanted. RESULTS: The incidence of aseptic loosening of the acetabular component after RTHA in uncontained loss of bone stock of the acetabulum (type III-IV as per the Gross and Saleh classification) using the CMAI was less than that using the SAI (2.4% and 10.0%, respectively). The most significant differences in aseptic loosening rates were noted after implantation of the CMAI and SAI in pelvic discontinuity with uncontained bone defect (0% and 60.0%, respectively; P<.001). CONCLUSION: The ideal indications for the use of the CMAI are uncontained defects and pelvic discontinuity with uncontained loss of bone stock (types III-V Gross and Saleh classification). Treatment of these defects with the SAI leads to a higher incidence of aseptic loosening requiring re-revisions. Further observation is required to assess the effectiveness of using the CMAI and SAI in the long-term follow-up period.

A prospective study on outcome of patient-specific cones in revision knee arthroplasty.

BACKGROUND: Cones are known to be good substitutes for metaphyseal and diaphyseal bone loss during revision total knee arthroplasty (RTKA). Often the off-the-shelf cones do not fit to the individual patient's anatomy. New 3D-printing additive technologies allow to develop patient-specific cones. The aim of this prospective study was to describe their outcome. METHODS: From 2017 until 2020, 35 patient-specific titanium cones (15 femoral and 20 tibial) were implanted during 31 RTKAs (45% varus-valgus constrained implants and 55% rotating hinges). Clinical outcome was evaluated using KSS, WOMAC and FJS-12 scoring systems at 12 and 24 months. No patients were lost for follow-up. RESULTS: In all cases, there were no technical difficulties in adapting the cones to both the host bone and the revision implant. By the time of performing data analysis (January 2021), none of the 31 patients needed revision surgery for any reason. At 12 months of follow-up, the mean values of scores for knee function improved significantly from baseline (p < 0.01): KSS-103.00 (min 100-max 111, SD 5.35), WOMAC-16.5 (min 9-max 24, SD 6.45), FJS-12-61.60 (min 52-max 76, SD 9.20). At 24 months, the trend towards improvement of functional results continued but did not reached statistical significance comparing to 12 months: KSS was 105.92 (min 95-max 155, SD 16.18), WOMAC-14.07 (min 0-max 42, SD 12.42), FJS-12-83.78 (min 65-max 97, SD 09.64). Radiographic signs of osteointegration were detected within the first 6 month after surgery in all cases. Loosening of femoral or tibial components as well as peri-prosthetic infection was not observed in any of the patients during the follow-up. CONCLUSION: The original additive technology for designing and producing patient-specific metaphyseal and diaphyseal cones with different porosity zones for extensive femoral and tibial bone defects in RTKA is precise and clinically effective solution, at least in the short term. It could be a valid alternative to "off-the-shelf" cones or sleeves as well as structural allografts and even mega-prosthesis, but a longer follow-up period is required to assess its medium- and long-term reliability.

Congenital anomalies of the kidney and the urinary tract: A murmansk county birth registry study.

BACKGROUND: Congenital anomalies of the kidney and the urinary tract (CAKUTs) are relatively common birth defects. The combined prevalence in Europe was 3.3 per 1000 in 2012. The risk factors for these anomalies are not clearly identified. The aims of our study were to calculate the birth prevalences of urinary malformations in Murmansk County during 2006 to 2011 and to investigate related prenatal risk factors. METHODS: The Murmansk County Birth Registry was the primary source of information and our study included 50,936 singletons in the examination of structure, prevalence and proportional distribution of CAKUTs. The multivariate analyses of risk factors involved 39,322 newborns. RESULTS: The prevalence of CAKUTs was 4.0 per 1000 newborns (95% confidence interval [CI], 3.4-4.5) and did not change during the study period. The most prevalent malformation was congenital hydronephrosis (14.2% of all cases). Diabetes mellitus or gestational diabetes (odds ratio [OR] = 4.77; 95% CI, 1.16-19.65), acute infections while pregnant (OR = 1.83; 95% CI, 1.14-2.94), the use of medication during pregnancy (OR = 2.03; 95% CI, 1.44-2.82), and conception during the summer (OR = 1.75; 95% CI 1.15-2.66) were significantly associated with higher risk of CAKUTs. CONCLUSION: The overall fourfold enhancement of the occurrence of urinary malformations in Murmansk County for the 2006 to 2011 period showed little annual dependence. During pregnancy, use of medications, infections, pre-existing diabetes mellitus, or gestational diabetes were associated with increased risk of these anomalies, as was conception during summer. Our findings have direct applications in improving prenatal care in Murmansk County and establishing targets for prenatal screening and women's consultations.

Intrawound navigation for custom-made acetabular component in revision total hip arthroplasty: Does it improve implant positioning?

Background: The number of hip revisions makes up over 12 % of all hip arthroplasty cases. For large acetabular defects custom-made acetabular component (CMAC) are required. Rates of malposition of CMACs are highly variable. Our study aims to develop a readily available, reliable and easily reproducible method for positioning of the CMAC. We tried to answer the following questions: 1) how often does the postoperative position of the implant corresponds to the planned one; 2) is the use of intrawound navigation improve the precision of acetabular implant position. Methods: This was a single-center observational cohort study and included two groups: the experimental group (use of 3D navigation for implant positioning) and the control group (no navigation use). All the patients were scheduled for acetabular revision surgery with custom-made 3D-printed acetabular components. All surgeries took place between 2016 and 2020. Results: 25 % freehand group, 85 % implants in the navigation group matched accuracy positioning criteria. The relative risk of malposition was significantly higher without the intraoperative navigation, with 5 times greater risk of malpositioning in the freehand group versus the navigation group. Conclusion: Navigation method allows planning of the implant and reamer sizes for optimal bone preparation and preservation. It provides easier implantation of the complex implant with reliable, stable primary fixation in massive bone defects. It reliably decreases malposition rate, allowing for implant placement in a proper position with sufficient bone-implant contact. Further research is needed to determine the relationship between CMAC position accuracy and long-term clinical and radiographic outcomes.

Safety and Immunogenicity of Betuvax-CoV-2, an RBD-Fc-Based SARS-CoV-2 Recombinant Vaccine: Preliminary Results of the First-in-Human, Randomized, Double-Blind, Placebo-Controlled Phase I/II Clinical Trial.

COVID-19, being a life-threatening infection that evolves rapidly, remains a major public health concern calling for the development of vaccines with broad protection against different pathogenic strains and high immunogenicity. Aside from this, other concerns in mass immunization settings are also the scalability of production and relative affordability of the technology. In that regard, adjuvanted protein vaccines with particles mimicking the virus stand out among known vaccine technologies. The "Betuvax-CoV-2" vaccine, developed on the basis of a recombinant protein and an adjuvant, has already been tested in preclinical studies and has advanced to clinical evaluation. Open, double-blinded, placebo-controlled, randomized phase I/II clinical trial of the "Betuvax-CoV-2," recombinant protein subunit vaccine based on the S-protein RBD fused with the Fc-fragment of IgG, was conducted to evaluate safety and immunogenicity in response to the vaccination. METHODS: In the phase I/II clinical trial, 116 healthy adult men and women, ages 18-58, were enrolled: 20 in Stage I, and 96 in Stage II. In Stage I, 20 µg of the vaccine was administered intramuscularly on day 2, and either 5 µg (group 1) or 20 µg (group 2) on day 30. In Stage II, 20 µg of the vaccine was administered intramuscularly on day 2, and either 5 µg (group 3) or 20 µg (group 4) on day 30. In group 5, both injections were replaced with placebo. The primary outcome measures were safety (number of participants with adverse events throughout the study) and antigen-specific humoral immunity (SARS-CoV-2-specific antibodies measured by ELISA and CMIA). Antigen-specific cell-mediated immunity and changes in neutralizing antibodies (detected with a SARS-CoV-2 neutralization assay) were measured as a secondary outcome. The trial is registered with ClinicalTrials.gov (Study Identifier: NCT05270954). FINDINGS: Both vaccine formulations (20 µg + 5 µg and 20 µg + 20 µg) were safe and well tolerated. Most adverse events were mild, and no serious adverse events were detected. On day 51,anti-SARS-CoV-2 total and IgG antibody titers and anti-SARS-CoV-2 neutralizing antibodies were significantly higher in the vaccine groups (both formulations) than in the placebo. A more pronounced CD4+-mediated immune response was observed in the group of volunteers administered with the 20 + 20 µg vaccine formulation. INTERPRETATIONS: RBD-Fc-based COVID-19 "Betuvax-CoV-2" vaccine in doses (20 + 5 µg and 20 + 20 µg) demonstrated an excellent safety profile and induced a strong humoral response. Further research on the protective effectiveness of the "Betuvax-CoV-2" vaccine for the prevention of COVID-19 is on its way.

Record efficiency of 1000 nm electroluminescence from a solution-processable host-free OLED.

New ytterbium complexes K(Solv)x[Yb(Ln)2] (Solv = ethanol and/or water) with 2-tosylaminobenzylidene-aryloylhydrazones (H2L1, aryloyl = benzoyl; H2L2, aryloyl = 2-naphthoyl) demonstrated high solubility and hole mobility (ca. 2.6 × 10-6 cm2 V-1 s-1), while their electron mobility and PLQY were different. The substitution of a benzoyl substituent with naphthoyl resulted in a significant increase of the electron mobility (6.9 × 10-7vs. 1.7 × 10-6 cm2 V-1 s-1) and a decrease of the quantum yield (1.2% vs. 0.6%). As a result, the optimized OLEDs based on the K[Yb(Ln)2] layer demonstrated efficiencies up to 385 µW W-1 and 441 µW W-1, indicating the superior importance of charge mobility over the quantum yield. These are the highest efficiencies of the Yb electroluminescence.

Perinatal mortality in relation to birthweight and gestational age: a registry-based comparison of Northern Norway and Murmansk County, Russia.

The objective was to explore how perinatal mortality relates to birthweight, gestational age and optimal perinatal survival weight for two Arctic populations employing an existing and a newly established birth registry. A medical birth registry for all births in Murmansk County of North-West Russia became operational on 1st January 2006. Its primary function is to provide useful information for health care officials pertinent to improving perinatal care. The cohort studied consisted of 17,302 births in 2006-07 (Murmansk County) and 16,006 in 2004-06 (Northern Norway). Birthweight probability density functions were analysed, and logistic regression models were employed to calculate gestational-age-specific mortality ratios. The perinatal mortality rate was 10.7/1000 in Murmansk County and 5.7/1000 in Northern Norway. Murmansk County had a higher proportion of preterm deliveries (8.7%) compared to Northern Norway (6.6%). The odds ratio (OR) of risk of mortality (Northern Norway as the reference group) was higher for all gestational ages in Murmansk County, but the largest risk difference occurred among term deliveries (OR 2.45, 95% confidence interval 1.45, 4.14) which hardly changed on adjustment for maternal age, parity and gestation. Proportionately, more babies were born near (± 500 g) the optimal perinatal survival weight in Murmansk County (67.2%) than in Northern Norway (47.6%). The observed perinatal mortality was higher in Murmansk County at all birthweight strata and at gestational ages between weeks 25 and 42, but the adjusted risk difference was most significant for term deliveries.

Sandwiched CoFe2O4/SrFe11.5Al0.5O19/CoFe2O4 nanoparticles with exchange-coupling effect.

Exchange-coupled hard/soft ferrite nanoparticles are prospective to squeeze out a part of expensive magnets based on rare-earth elements. However, the known exchange-coupled composite ferrite nanoparticles often suffer from the lack of a powerful enough hard magnetic core, high defectivity of magnetic phases, and a poor interface between them. Herein, we demonstrate the first efficient synthesis of sandwiched nanomagnets, which exhibit a pronounced exchange-coupling effect. This work is featured by the use of individual highly coercive strontium hexaferrite nanoplates prepared by a borate glass crystallization method as cores for the composite particles. The high crystal quality of the hexaferrite cores as the substrate promotes the epitaxial growth of CoFe2O4 layers on the 001 facets from an organic high-boiling solvent and results in the enhancement of the remanent magnetization and maximum energy product of the composite material. The results of this work open new prospects for the fabrication of multilayer oxide heterostructures with synergetic performance, which expands the applications of exchange-coupled composites.

A near-infrared emitting MOF: controlled encapsulation of a fluorescein sensitizer at the time of crystal growth.

We report here a near-infrared (NIR) emitting lanthanide-based metal-organic framework (MOF) in which Yb3+ are sensitized by fluorescein (FL) as a low energy absorbing chromophore (FL@CD-MOF-161). The unique design of CD-MOF-161 allows for the entrapment of FL molecules in its pores during the synthesis and crystal growth, ensuring the efficient loading and spreading of chromophores within the crystal volume.

Highly NIR-emitting ytterbium complexes containing 2-(tosylaminobenzylidene)-N-benzoylhydrazone anions: structure in solution and use for bioimaging.

Solution behaviour in DMSO using 1D and 2D NMR spectroscopy was performed for lanthanide complexes Ln(L)(HL) and Ln(HL)2Cl, containing non-macrocyclic 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), and the structure of [Yb(L)]+ cation in solution was determined. Based on the NMR data, the possibility to obtain novel complexes containing [Ln(L)2]- was predicted, which was successfully synthesized, and the crystal structure of K(C2H5OH)3[Yb(L)2] was determined. Thanks to its high quantum yield of NIR luminescence (1.3 ± 0.2%), high absorption, low toxicity, and the stability of its anion against dissociation in DMSO, K(H2O)3[Yb(L)2] was successfully used for bioimaging.

Fibrin Glue Implants Seeded with Dental Pulp and Periodontal Ligament Stem Cells for the Repair of Periodontal Bone Defects: A Preclinical Study.

A technology to create a cell-seeded fibrin-based implant matching the size and shape of bone defect is required to create an anatomical implant. The aim of the study was to develop a technology of cell-seeded fibrin gel implant creation that has the same shape and size as the bone defect at the site of implantation. Using computed tomography (CT) images, molds representing bone defects were created by 3D printing. The form was filled with fibrin glue and human dental pulp stem cells (DPSC). The viability, set of surface markers and osteogenic differentiation of DPSC grown in fibrin gel along with the clot retraction time were evaluated. In mice, an alveolar bone defect was created. The defect was filled with fibrin gel seeded with mouse DPSC. After 28 days, the bone repair was analyzed with cone beam CT and by histological examination. The proliferation rate, set of surface antigens and osteogenic potential of cells grown inside the scaffold and in 2D conditions did not differ. In mice, both cell-free and mouse DPSC-seeded implants increased the bone tissue volume and vascularization. In mice with cell-seeded gel implants, the bone remodeling process was more prominent than in animals with a cell-free implant. The technology of 3D-printed forms for molding implants can be used to prepare implants using components that are not suitable for 3D printing.

Risk Factors for hypospadias in Northwest Russia: A Murmansk County Birth Registry Study.

BACKGROUND: Hypospadias is the most common congenital anomaly of the penis, but its causes are mainly unknown. Of the risk factors identified, the most plausible are hormonal and genetic. The aim of this study was to identify risk factors for hypospadias in Northwest Russia based on registry data. METHODS: The study population included male infants registered in the Murmansk County Birth Registry between 1 January 2006 and 31 December 2011 (n = 25 475). These infants were followed-up for 2 years using the Murmansk Regional Congenital Defects Registry to identify cases of hypospadias not diagnosed at birth. We used logistic regression analysis to examine the contributions of hypospadias risk factors. RESULTS: Out of 25 475 male infants born during the study period, 148 had isolated hypospadias. The overall prevalence rate was 54.2 (95% CI 53.6-54.8) per 10 000 male infants. Those born to mothers with preeclampsia (OR = 1.65; 95% CI 1.03-2.66) or infant birthweight < 2500 g (OR = 2.06; 95% CI 1.18-3.60) exhibited increased risk for hypospadias. Maternal age, smoking during pregnancy, folic acid intake during pregnancy or hepatitis B surface antigen positivity did not associate with increased risk of hypospadias. CONCLUSIONS: Combining data from a birth registry with those from a congenital defects registry provided optimal information about the prevalence of hypospadias and its association with low infant birthweight and preeclampsia. These factors have in common changes in hormone levels during pregnancy, which in turn may have contributed to hypospadias development.

Implementation, quality control and selected pregnancy outcomes of the Murmansk County Birth Registry in Russia.

OBJECTIVES: To describe the essential features of the newly established Murmansk County Birth Registry (MCBR); make some preliminary comparisons of selected variables related to pregnancy and delivery in northern counties of the Nordic countries and in cities and towns of Murmansk County [Murmanskaja Oblast (MO)] and explore some research possibilities. STUDY DESIGN: A registry-based cohort study. METHODS: The MCBR was established in 2005 and registration began on 1 January 2006. A registry form draws upon both hospital files and information from the mother. There are 54 major fields consisting primarily of tick-off boxes and International Classification of Diseases (ICD-10) codes. A quality control exercise was conducted in both 2006 and 2007. RESULTS: During 2006, 8,468 births were registered in the MO (coverage = 98.9%). The proportion of errors was below 1% in both years. Limiting the descriptive statistics to 2006, compared to counties of the Nordic counties in the Barents Region, the delivering women in the MO were younger and had fewer and lighter (mean of 200 g) babies. The gestational age was somewhat shorter in the MO than in the Nordic counties and fewer babies had a birthweight above 4,500 g. The perinatal mortality corresponding to a gestational age (GA) of either 22 or 28 completed weeks was higher (p < 0.02) in the MO than the Nordic counties in this study. In the MO, the birth rate does not balance the reported increase in death rate. CONCLUSIONS: Our study concludes that a medical birth registry of satisfactory quality has been established for the world's largest arctic population.

The peculiarities of complex formation and energy transfer processes in lanthanide complexes with 2-(tosylamino)-benzylidene-N-benzoylhydrazone.

Depending on the local excess of lanthanide ions (Ln = Lu, Yb, Er, Dy, Tb, Gd, Eu, Nd) or 2-(tosylamino)-benzylidene-N-benzoylhydrazone (H2L), lanthanide complexes, containing either a mono-deprotonated ligand (Ln(HL)2X, X = Cl, NO3) or both mono- and dideprotonated ligands (Ln(L)(HL)), were preparatively obtained. The crystal structures of Lu(HL)2Cl, Yb(L)(HL)(H2O)2, Yb(L)(HL)(EtOH)2(H2O) and Er(L)(HL), determined by single crystal diffraction data or from powder diffraction data using Rietveld refinement, have shown the surprising resemblance. The study of luminescence temperature dependence of Eu(HL)2Cl and Eu(L)(HL) showed that europium luminescence is quenched by thermally-activated 5D0 → T1 energy transfer. Luminescent thermometers based on these complexes demonstrated the sensitivity of up to 7.7% at 85 K which is the highest value above liquid-nitrogen temperatures obtained to date.

Risk Factors for Ventricular Septal Defects in Murmansk County, Russia: A Registry-Based Study.

Cardiovascular malformations are one of the most common birth defects among newborns and constitute a leading cause of perinatal and infant mortality. Although some risk factors are recognized, the causes of cardiovascular malformations (CVMs) remain largely unknown. In this study, we aim to identify risk factors for ventricular septal defects (VSDs) in Northwest Russia. The study population included singleton births registered in the Murmansk County Birth Registry (MCBR) between 1 January 2006 and 31 December 2011. Infants with a diagnosis of VSD in the MCBR and/or in the Murmansk Regional Congenital Defects Registry (up to two years post-delivery) constituted the study sample. Among the 52,253 infants born during the study period there were 744 cases of septal heart defects (SHDs), which corresponds to a prevalence of 14.2 [95% confidence interval (CI) of 13.2⁻15.3] per 1000 infants. Logistic regression analyses were carried out to identify VSD risk factors. Increased risk of VSDs was observed among infants born to mothers who abused alcohol [OR = 4.83; 95% CI 1.88⁻12.41], or smoked during pregnancy [OR = 1.35; 95% CI 1.02⁻1.80]. Maternal diabetes mellitus was also a significant risk factor [OR = 8.72; 95% CI 3.16⁻24.07], while maternal age, body mass index, folic acid and multivitamin intake were not associated with increased risk. Overall risks of VSDs for male babies were lower [OR = 0.67; 95% CI 0.52⁻0.88].

Acetabular cup version modelling and its clinical applying on plain radiograms.

AIM: To measure the sensitivity and specificity of the cup version assessment by using only anteroposterior hip and pelvis views, evaluate the incidence of inadequate cup version in patients with repeated dislocations after total hip arthroplasty (THA). METHODS: Radiographic retrospective analysis of 2 groups of patients, with follow up of 6-60 mo, after undergoing primary THA. First group of 32 patients (20 female, 12 male) with unilateral THA (32 hips) required early revision arthroplasty for reasons of dislocation. The mean age and mode were 59 (from 38 to 83) and 66 ages respectively. The average body mass index (BMI) was 24.2 (from 17.7 to 36.3), mode 23.9. Second group was consisted of 164 patients (101 female, 63 male) without dislocations during the follow-up period (170 hips). Among them 6 patients required bilateral THA. The mean age was 60 (from 38 to 84) and mode 59. BMI was 24.8 (17.2-36.8), mode 25.2. Clinical significance of the cup anteversion sign was estimated with cross tabulation 2 × 2. RESULTS: The value of the χ2 yates was 10.668 (P < 0.01). Sensitivity of SAI (sign of anteversion insufficiency) was 29% (95%CI: 9%-46%), and specificity was 92% (95%CI: 88%-96%). Relative risk of dislocation in patients with SAI was 3.4 (95%CI: 1.8-6.3). CONCLUSION: This method provides the surgeons with the ability to perform a reliable and simple qualitative assessment of the acetabular component version. It can be useful during patient examination with early loosening of the implant, dislocations, and impingement. Additionally, it can provide necessary information during planning of revision surgery, especially when considering question about cup replacement, although final assessment of the cup position should be done with a computed tomography scan.

Under-reporting of major birth defects in Northwest Russia: a registry-based study.

The objective was to assess the prevalence of selected major birth defects, based on data from two medical registries in Murmansk County, and compare the observed rates with those available for Norway and Arkhangelsk County, Northwest Russia. It included all newborns (≥22 completed weeks of gestation) registered in the Murmansk County Birth Registry (MCBR) and born between 1 January 2006 and 31 December 2009 (n=35,417). The infants were followed-up post-partum for 2 years through direct linkage to the Murmansk Regional Congenital Defects Registry (MRCDR). Birth defects identified and confirmed in both registries constituted the "cases" and corresponded to one or more of the 21 birth defect types reportable to health authorities in Moscow. The overall prevalence of major birth defects recorded in the MRCDR was 50/10,000 before linkage and 77/10,000 after linkage with the MCBR. Routine under-reporting to the MRCDR of 40% cases was evident. This study demonstrates that birth registry data improved case ascertainment and official prevalence assessments and reduced the potential of under-reporting by physicians. The direct linkage of the two registries revealed that hypospadias cases were the most prevalent among the major birth defects in Murmansk County. ABBREVIATIONS: ICD-10, International Classification of Diseases, 10th revision; MCBR, Murmansk County Birth Registry; MRCDR, Murmansk Regional Congenital Defects Registry; MGC, Murmansk Genetics Center.

Redox and complexation interactions of neptunium(V) with quinonoid-enriched humic derivatives.

Actinides in their higher valence states (e.g., MO2+ and MO2(2+), where M can be Np, Pu, etc) possess a higher potential for migration and in turn pose a substantial environmental threat. To minimize this potential for migration, reducing them to lower oxidation states (e.g., their tetravalent state) can be an attractive and efficient remedial process. These lower oxidation states are often much less soluble in natural aqueous media and are, therefore, less mobile in the environment. The research presented here focuses on assessing the performance of quinonoid-enriched humic derivatives with regardsto complexing and/ or reducing Np(V) present in solution. These "designer" humics are essentially derived reducing agents that can serve as reactive components of a novel humic-based remediation technology. The derivatives are obtained by incorporating different quinonoid-moieties into leonardite humic acids. Five quinonoid-derivatives are tested in this work and all five prove more effective as reducing agents for selected actinides than the parent leonardite humic acid, and the hydroquinone derivatives are better than the catechol derivatives. The reduction kinetics and the Np(V) species formed with the different derivatives are studied via a batch mode using near-infrared (NIR)-spectroscopy. Np(V) reduction by the humic derivatives under anoxic conditions at 293 K and at pH 4.7 obeys first-order kinetics. Rate constants range from 1.70 x 10(-6) (parent humic acid) to 1.06 x 10(-5) sec(-1) (derivative with maximum hydroquinone content). Stability constants for Np(V)-humic complexes calculated from spectroscopic data produce corresponding Logbeta values of 2.3 for parent humic acid and values ranging from 2.5 to 3.2 at pH 4.7 and from 3.3 to 3.7 at pH 7.4 for humic derivatives. Maximum constants are observed for hydroquinone-enriched derivatives. It is concluded that among the humic derivatives tested, the hydroquinone-enriched ones are the most useful for addressing remedial needs of actinide-contaminated aquifers.

Design of quinonoid-enriched humic materials with enhanced redox properties.

The primary goal of this work was to develop quinonoid-enriched humic materials with enhanced redox properties that could be used as potentially effective redox mediators and reducing agents for in situ remediation of soil and aquatic environments. Two different strategies were formulated and tested to derive these materials. The first strategy called for the oxidation of phenolic fragments associated with the humic aromatic core. In a second strategy, polycondensation of these phenolic fragments was carried out with hydroquinone and catechol. The oxidized derivatives and copolymers obtained were characterized using elemental and functional group analyses, and capillary zone electrophoresis. The redox properties were evaluated using ESR spectrometry and reducing capacity determinations. The reducing capacities of copolymers ranged between 1 and 4 mmol/g, which were much higher than the parent material and the oxidized derivatives. Hence, preference should be given to the copolycondensation approach. The quinonoid-enriched humics are nontoxic, water soluble, and resistant to biodegradation; thus, they could be applied as soil amendments to reduce highly mobile oxoanions of heavy metals and radionuclides, or as redox mediators to enhance in situ bioremediation. Otherwise, cross-linked copolymers could be created to serve as inexpensive reductants in permeable reactive barriers designed to remove highly oxidized contaminants from polluted groundwaters.