Long-term Immobilization Research Articles

Long-Term Immobilization of Technetium via Bioremediation with Slow-Release Substrates.

Radionuclides are present in groundwater at contaminated nuclear facilities with technetium-99, one of the most mobile radionuclides encountered. In situ bioremediation via the generation of microbially reducing conditions has the potential to remove aqueous and mobile Tc(VII) from groundwater as insoluble Tc(IV). However, questions remain regarding the optimal methods of biostimulation and the stability of reduced Tc(IV) phases under oxic conditions. Here, we selected a range of slow-release electron donor/chemical reduction based substrates available for contaminated land treatment, and assessed their potential to stimulate the formation of recalcitrant Tc(IV) biominerals under conditions relevant to radioactively contaminated land. These included a slow-release polylactate substrate (HRC), a similar substrate with an additional organosulfur ester (MRC) and a substrate containing zerovalent iron and plant matter (EHC). Results showed that Tc was removed from solution in the form of poorly soluble hydrous Tc(IV)-oxides or Tc(IV)-sulfides during the development of reducing conditions. Reoxidation experiments showed that these phases were largely resistant to oxidative remobilization and were more resistant than Tc(IV) produced via biostimulation with an acetate/lactate electron donor mix in the sediments tested. The implications of the targeted formation of recalcitrant Tc(IV) phases using these proprietorial substrates in situ is discussed in the context of the long-term management of technetium at legacy nuclear sites.

Calf muscle functional deficit 1-year after Achilles tendon rupture repair surgery

The primary muscles responsible for plantar flexion movement are soleus and gastrocnemius which connects to the calcaneus by the Achilles tendon. Achilles tendon rupture is managed most often with open surgical repair in which the affected limb is immobilized. Understanding the effects of long-term immobilization, how these lead to changes in the physiological properties of the calf muscles changes, may help to improve rehabilitation. Investigating the biomechanical behavior of the calf muscles may provide a better understanding of how the inferior material properties of a scarred Achilles tendon may influence the more global structural properties of the intact muscles

A Potential Wasteform for Cs Immobilization: Synthesis, Structure Determination, and Aqueous Durability of Cs2TiNb6O18.

Cs2TiNb6O18 is a potential ceramic wasteform for the long-term immobilization of radioactive cesium. Cs2TiNb6O18 was synthesized using the aqueous precursor method and a solid-state reaction, and its crystal structure was determined from the Rietveld refinement of synchrotron X-ray and neutron powder diffraction data. The structure is a pyrochlore analogue, space group P3̅m1 with Cs in 9-fold coordination. The calculated bond valence sum from analysis of neutron diffraction data of 0.84 and high coordination number suggest that Cs has a strong bonding environment. The chemical aqueous durability was investigated using the MCC-1 and PCT-B standard test methods. The measured Cs leach rates of 3.8 × 10-3 and 2.1 × 10-3 g m-2 day-1 obtained via the MCC-1 and PCT-B methods, respectively, demonstrate good promise of a safe long-term immobilization material comparable to, if not better than, hollandite-the material in the multiphase titanate ceramics (Synroc) targeted for cesium sequestration.

A Deeper Look into Type 1 Diabetes - Imaging Immune Responses during Onset of Disease.

Cytotoxic T lymphocytes execute the killing of insulin-producing beta cells during onset of type 1 diabetes mellitus (T1D). The research community has come far in dissecting the major events in the development of this disease, but still the trigger and high-resolved information of the immunological events leading up to beta cell loss are missing. During the past decades, intravital imaging of immune responses has led to significant scientific breakthroughs in diverse models of disease, including T1D. Dynamic imaging of immune cells at the pancreatic islets during T1D onset has been made possible through the development of both advanced microscopes, and animal models that allow long-term immobilization of the pancreas. The use of these modalities has revealed a milling microenvironment at the pancreatic islets during disease onset with a plethora of active players. Clues to answering the remaining questions in this disease may lie in intravital imaging, including how key immune cells traffic to and from the pancreas, and how cells interact at this target tissue. This review highlights and discusses recent studies, models, and techniques focused to understand the immune responses during T1D onset through intravital imaging.

Combined effects of radiation damage and He accumulation on bubble nucleation in Gd2Ti2O7

Pyrochlores have long been considered as host phases for long-term immobilization of radioactive waste nuclides that would undergo α-decay for hundreds of thousands of years. This work utilizes ion-beam irradiations to examine the combined effects of radiation damage and He accumulation on bubble formation in Gd2Ti2O7 over relevant waste-form timescales. Helium bubbles are not observed in pre-damaged Gd2Ti2O7 implanted with 2 × 1016 He/cm2, even after post-implantation irradiations with 7 MeV Au3+ at 300, 500, and 700 K. However, He bubbles with average diameters of 1.5 nm and 2.1 nm are observed in pre-damaged (amorphous) Gd2Ti2O7 and pristine Gd2Ti2O7, respectively, after implantation of 2 × 1017 He/cm2. The critical He concentration for bubble nucleation in Gd2Ti2O7 is estimated to be 6 at.% He.

Influence of long-term immobilization of the wrist on motor imagery ability

Influence of long-term immobilization of the wrist on motor imagery ability

Forearm Positioning and Its Functional Implications

Current management of numerous pathologies, including triangular fibrocartilage complex tears, distal radial ulnar joint instability, and both bone fractures, often consist of a long-term block to forearm rotation in a supinated position. In the extremes of rotation a mulsculotendinous imbalance is created; long-term immobilization in supination can potentially lead to secondary difficulties in regaining full mobility, as observed clinically. Long-term immobilization has functional implications for the patient in terms of daily living activities and skilled use of the hand. The purpose of this paper is to illustrate the functional implications of forearm positioning.

Application of titanium-containing sorbents for treating liquid radioactive waste with the subsequent conservation of radionuclides in Synroc-type titanate ceramics

New nanocrystalline titanium-containing sorbents, namely, layered hydrazinium titanate LHT-9, (N2H5)0.5Ti1.87O4 and synthetic ivanyukite-Na Na2K[Ti4(OH)O3(SiO4)3] · 7H2O, possess high sorption capacity towards cations of different valences and, due to their high chemical stability in acidic and alkaline media, provide the purification of liquid radioactive waste of any composition. The calcination of the product of the radionuclide sorption on LHT-9 and ivanyukite at 1000–1200°C yields mineral-like Synroc-type titanate ceramics applicable for long-term immobilization of sorbed radionuclides with a significant (by 17–250 times) decrease in the amount of radioactive waste.

Evaluating the impacts of fine-scale capillary heterogeneity and wettability on the behavior of buoyancy-driven CO2 migration and trapping mechanisms

One of the primary concerns in CO2 sequestration is long-term immobilization of CO2. There are several storage mechanisms to immobilize CO2 in a porous medium: structural, dissolution, residual, and mineral trapping. Storage analysis with fine-scale heterogeneity requires the investigation of a newly suggested mechanism: capillary barrier trapping. This study covers a quantitative assessment of the CO2 trapping capacity with residual, dissolution, and capillary barrier trapping mechanisms in heterogeneous formations. The effects of heterogeneity on CO2 trapping capacity are studied under different wettability scenarios. The Leverett J-function is applied so that every grid block has a different drainage capillary pressure curve, which is physically consistent with its heterogeneous properties and wettability. Based on contact angle, residual saturation and relative permeability curves are modeled. Different heterogeneity and wettability causes considerable variations in leakage of CO2, ranging from 6 to 38 %. The lateral correlation length of permeability affects the spatial distribution of CO2. As the permeability variation increases, the total amount of trapped CO2 increases significantly indicating a reduced potential risk of leakage. Although the residual and dissolution trappings decreases as the wetting condition changes from strongly water-wet to intermediate gas-wet, the amount of CO2 trapped by the capillary barriers increases considerably, and the mobile phase saturation of the CO2 is reduced. The results of this study have emphasized the importance of capillary barrier trapping, which takes a large portion of the immobilized CO2 phase, for stable underground storage.

Polysomatism and structural complexity: structure model for murataite-8C, a complex crystalline matrix for the immobilization of high-level radioactive waste

Murataite-8 C , a prospective synthetic material for the long-term immobilization of high-level radioactive waste and a member of the pyrochlore–murataite polysomatic series, was investigated by means of single-crystal X-ray diffraction. The crystal structure (cubic, F -43 m , a = 39.105(12) A, V = 59799(32) A3, Z = 4) is of outstanding complexity and contains forty symmetrically independent cation sites. Its crystal-chemical formula determined on the basis of the crystal-structure refinement, Al25.44Ca55.96Ti282.20Mn53.72Fe17.24Zr15.00Ho36.64O823, is in good agreement with the empirical formula calculated from electron-microprobe data, Al23.02Ca52.85Ti284.10Mn54.31Fe17.59Zr14.83Ho38.04O823. The crystal structure is based upon a three-dimensional octahedral framework that can be described as an alternation of murataite and pyrochlore modules immersed into a transitional substructure that combine elements of the crystal structures of murataite-3 C and pyrochlore. The obtained structural model confirms the polysomatic nature of the pyrochlore–murataite series and illuminates the chemical and structural peculiarities of crystallization of the murataite-type titanate ceramic matrices. The high chemical and structural complexity of the members of the pyrochlore–murataite series is unparalleled in the world of crystalline materials proposed for the high-level radioactive waste immobilization, which makes it unique and promising for further technological and scientific exploration.

Controls on the Fate and Speciation of Np(V) During Iron (Oxyhydr)oxide Crystallization.

The speciation and fate of neptunium as Np(V)O2(+) during the crystallization of ferrihydrite to hematite and goethite was explored in a range of systems. Adsorption of NpO2(+) to iron(III) (oxyhydr)oxide phases was reversible and, for ferrihydrite, occurred through the formation of mononuclear bidentate surface complexes. By contrast, chemical extractions and X-ray absorption spectroscopy (XAS) analyses showed the incorporation of Np(V) into the structure of hematite during its crystallization from ferrihydrite (pH 10.5). This occurred through direct replacement of octahedrally coordinated Fe(III) by Np(V) in neptunate-like coordination. Subsequent analyses on mixed goethite and hematite crystallization products (pH 9.5 and 11) showed that Np(V) was incorporated during crystallization. Conversely, there was limited evidence for Np(V) incorporation during goethite crystallization at the extreme pH of 13.3. This is likely due to the formation of a Np(V) hydroxide precipitate preventing incorporation into the goethite particles. Overall these data highlight the complex behavior of Np(V) during the crystallization of iron(III) (oxyhydr)oxides, and demonstrate clear evidence for neptunium incorporation into environmentally important mineral phases. This extends our knowledge of the range of geochemical conditions under which there is potential for long-term immobilization of radiotoxic Np in natural and engineered environments.

Etiopathogenesis, Prevention, and Treatment of Thromboembolism in Inflammatory Bowel Disease

The close relationship between inflammation and thrombosis affects the progression and severity of inflammatory bowel disease (IBD). The prevalence of venous thromboembolism (VTE) varies between 1% and 7% among patients with IBD. The VTE risk in patients with IBD is at least 3 times higher than that in the normal general population. The absolute risk is very high during hospitalization, active disease, and surgery. The IBD-related VTE occurs at younger ages and recurs more frequently. The development of thrombosis in IBD is due to the interaction of many hereditary and acquired risk factors. Each patient diagnosed with IBD should be evaluated for a personal and family history of thrombosis and for prothrombotic drug use. Although procoagulant factors are increased during the natural course of inflammation, natural anticoagulants and fibrinolytic activity are decreased. Although IBD is accepted as a prothrombotic condition, there is no treatment that can remove this risk from daily practice. Patient training is required to control important factors, such as long-term immobilization and smoking. Oral contraceptives and hormone replacement therapy should be avoided. Inducing permanent disease remission must be the key approach for the prevention of thrombosis. Low-molecular-weight heparin (LMWH) is the basis of prophylactic treatment, which reduces the thrombosis risk by 50%. Prophylaxis with LMWH should be administered to all patients with IBD hospitalized due to disease attack or surgery. Long-term or even life-long anticoagulation therapy should be planned if there is insufficient disease control, recurrent VTE attacks, positive thrombophilia tests, or thrombosis in vital veins.

Busted, Plausible or Confirmed

Busted, Plausible or Confirmed

Ankle fusion with a retrograde locked intramedullary nail for sequela of lower extremity compartment syndrome

ObjectiveTo assess the value of ankle fusion with a retrograde locked intramedullary nail in the treatment of sequela of lower extremity compartment syndrome. MethodsThirty-five cases of equinus deformity following tibiofibular compartment syndrome treated by means of ankle fusion with a retrograde locked intramedullary nail from January 2001 to December 2010 were retrospectively reviewed. The complications, the time needed for bony fusion of the ankle joint assessed by anteroposterior and lateral X-ray photographs as well as patients’ subjective evaluation were recorded and analysed. ResultsAmong the 35 patients, 15 had previously undergone surgical treatment twice on the same limb, 13 had thrice and 7 had to be operated on four times before ankle fusion. An anterior midpoint approach to the ankle joint was adopted in 29 cases, while anterior midpoint approach plus a small incision on the posterior ankle joint was made in 17 cases, whereas lateral approach in 6 cases. Tarsus joint fusion was performed on 4 cases. The follow-up period ranged 6-124 months, averaged 40.6 months. Bone grafting was not performed in this series. Preoperative tibial shaft fracture occurred in one patient and was healed after conservative treatment. Incision dehiscence located at previous Achilles tendon incision was found in two patients. As a result, one received an intramedullary nail emplacement at calcaneoplantar part while the wound at anterosuperior part of the other one was healed by dressing change. Two patients failed to bony union 5 months postoperatively, in which one healed 10 weeks after retrieval of proximal tibial nail and another by iliac grafting. Terminal necrosis of the toe due to blood supply dysfunction was not found in this series. All the patients were satisfied with the ankle joint function postoperatively. The time for bony union on X-rays was 9.8 weeks on average. Except for one patient who demanded removal of intramedullary nail, all the intramedullary nails were not retrieved at the end of follow-up. Nail breakage happened in one patient and no other breakage or backing out of the nail was found. ConclusionsLower extremity compartment syndrome and residual ankle deformity often extremely impact ambulation and are hard to deal with because several pathologic phenomena might exist in these patients, for instance, poor skin conditions due to repeated preexisting surgery; poor perfusion in distal limbs following blood vascular injury; reflux limitation and long-term limb swelling due to muscle strength disturbance; osteoporosis as a result of long-term immobilization or limb disuse. Ankle fusion with a retrograde locked intramedullary nail is an optimal protocol to solve these clinical symptoms and rather ensures a definite fusion and firm fixation to these patients with simple manipulation and few complications.

Safe long-term immobilization of heavy metals: Looking at natural rocks

Portland cement clinker is primarily used in building and construction, with a global annual production of ~4 billion tonnes. Part of it is also used for immobilization of hazardous materials (e.g., industrial slurries, harbor bottom sludge, shredded tires), notably those containing toxic metals like e.g., zinc, cadmium, barium (Trezza and Scian 2000). Limited amounts may be added to the raw meal and get incorporated into the clinker minerals upon burning (Taylor 1997), assuming they remain immobilized in the high-pH concrete or mortar environment after hydration and setting of the cement. Extensive laboratory tests seem to confirm effective mobilization, but are generally of limited duration for reason of practicality. Access to sample materials from centennia- or millennia-old structures is limited for reasons of cultural heritage preservation, and none of these structures were originally designed for environmental reasons. The paper by Khoury et al. (2016) analyzes uncommon combustion-metamorphic rocks from Jordan closely resembling cement-immobilized waste, exposed to supergene weathering and alteration over time spans far exceeding experimental practicality.

Collagen Type III and VI Turnover in Response to Long-Term Immobilization

BackgroundMuscle mass and function are perturbed by immobilization and remobilization. When muscle mass changes, the quality and quantity of the extracellular matrix protein, particularly the collagens, change with it. In this study, we investigated the temporal profile of three peptide biomarkers derived from turnover of collagen type III and type VI in a long-term immobilization and remobilization study. We also compared individual biomarker levels with Lean body Mass (LBM) and changes therein, hypothesizing that these biomarkers would be biomarkers of the remodeling processes associated with immobilization and/or remobilization.MethodsIn the Berlin bed rest study, 20 young men were recruited and randomly assigned to 8-week’s strict bed rest with or without resistive vibration exercise countermeasure. We measured three neo-epitope ELISA kits in the serum samples of this study: Pro-C3, measured the synthesis of collagen type III; Pro-C6, measured the synthesis of collagen type VI; and C6M measured the degradation of collagen type VI induced by MMP-2 and MMP-9 cleavage.ResultsPro-C3 and Pro-C6 biomarkers are up-regulated with both immobilization and remobilization, whereas C6M is hardly affected at all. We found that Pro-C3 and C6M levels are related to LBM at baseline and that high levels of Pro-C6 are associated with smaller changes in muscle mass during both immobilization and remobilization.ConclusionThe Pro-C3 and–C6 biomarkers change likely reflect remodeling changes in response to unloading or reloading, whereas C6M does not appear to respond to unloading. Pro-C3 and C6M levels correlate with LBM at baseline, while Pro-C6 is related to the anabolic and catabolic responses to unloading and reloading.

The Effect of Joint Mobilization on the Expressions of Nadph-Diaphorase and Nitric Oxide Synthase in the Spinal Cord Neurons

Knee joint immobilization is common medical practice used to manage musculoskeletal injuries; however, immobilization of the knee joint for a period generally causes degenerative alterations in many articular tissues (He & Dishman, 2009). Together with the articular tissues, neural tissue in the knee joint will also be altered after knee joint immobilization (Fuglsang-Frederiksen & Scheel, 1978; Michinaka et al., 1997; Kanemura et al., 2002). Progressive degeneration of articular tissues by immobilization of the knee joint, especially longterm immobilization appears to result in the Knee joint problems. Knee joint problems are one of the most common ailments of the musculoskeletal system and can produce pain. Chiropractic manipulative therapy can be helpful in alleviating some of the pain in knee joint problems (Xiaohua et al., 2008), and are also effective on extremity conditions (Hoskins et al., 2001; Nelson et al., 2005). Recent interest in nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) and nitric oxide synthase (NOS) has been focused on its expression in motor neurons of the central nervous system (CNS) after peripheral nerve injury (Gonzalez et al., 1987; Lei et al., 1992; Wu & Li, 1993; Hama & Sagen, 1994; Wu et al., 1994; Hee et al., 1997). NADPH-d had been detected in a subpopulation of neurons in the CNS and myentric plexus (Bredt et al., 1990; Hee et al., 1997). NOS is an enzyme for generation of nitric oxide (NO) which is implicated in a multiplicity of biological functions (Vincent & Hope, 1992; Pannu & Singh, 2006). At the CNS, it is known that, low concentrations of NO promote neuronal survival and growth (Dimmeler & Zeiher, 1999; Xiong et al., 1999), while high concentrations exert toxic effects and neuron death

Augmentation with antibiotic-impregnated spacers in sepsis revision surgery

The development of antibiotic-impregnated polymethyl methacrylate (PMMA) spacers is based on clinical experience and the use of antibiotic-loaded PMMA beads in septic bone surgery as well as antibiotic-loaded bone cement in arthroplasty beginning in the 1970s. In the meantime hand-formed and prefabricated spacers are implanted in cases of sepsis to achieve high local antibiotic concentrations and bactericidal effects to eradicate the infection. Preformed spacers with gentamicin are commercially available and furthermore, clindamycin-loaded PMMA bone cement can also be used. In principle, all thermostable antibiotics can be mixed with PMMA cement. Spacers permit bridging of bone defects originating from trauma or septic bone segment resection. After joint resection spacers allow a certain degree of articulation and inhibit shortening of the extremity which has a positive effect on the soft tissue covering and its perfusion. The functional outcome after secondary arthroplasty is better if a spacer has been implanted compared to long-term immobilization without spacers. Nevertheless, spacers can also cause serious complications, such as dislocations and fractures. Antibiotic-loaded spacers have therefore widened the therapeutic options in sepsis surgery.

Assessing Single Upconverting Nanoparticle Luminescence by Optical Tweezers.

We report on stable, long-term immobilization and localization of a single colloidal Er(3+)/Yb(3+) codoped upconverting fluorescent nanoparticle (UCNP) by optical trapping with a single infrared laser beam. Contrary to expectations, the single UCNP emission differs from that generated by an assembly of UCNPs. The experimental data reveal that the differences can be explained in terms of modulations caused by radiation-trapping, a phenomenon not considered before but that this work reveals to be of great relevance.

Natural attenuation of arsenic in the environment by immobilization in nanostructured hematite

Iron (hydr)oxides are known to play a major role in arsenic fixation in the environment. The mechanisms for long-term fixation into their crystal structure, however, remain poorly understood, especially arsenic partitioning behavior during transformation from amorphous to crystalline phases under natural conditions. In this study, these mechanisms are investigated in Fe–Al-oxisols exposed over a period of 10years to a sulfide concentrate in tailings impoundments. The spatial resolution necessary to investigate the markedly heterogeneous nanoscale phases found in the oxisols was achieved by combining three different, high resolution electron microscopy techniques – Nano-Beam Electron Diffraction (NBD), Electron Energy-Loss Spectroscopy (EELS), and High Resolution Transmission Electron Microscopy (HRTEM). Arsenic (1.6±0.5wt.%) was unambiguously and precisely identified in mesocrystals of Al-hematite with an As/Fe atomic ratio of 0.026±0.006. The increase in the c-axis (c=1.379±0.009nm) compared to standard hematite (c=1.372nm) is consistent with the presence of arsenic in the Al-hematite structure. The As-bearing Al-hematite is interpreted as a secondary phase formed from oxyhydroxides, such as ferrihydrite, during the long-term exposure to the sulfide tailings. The proposed mechanism of arsenic fixation in the Al-hematite structure involves adsorption onto Al-ferrihydrite nanoparticles, followed by Al-ferrihydrite aggregation by self-assembly oriented attachment and coalescence that ultimately produces Al-hematite mesocrystals. Our results illustrate for the first time the process of formation of stable arsenic bearing Al-hematite for the long-term immobilization of arsenic in environmental samples.