Biological Fixation Research Articles

Nitrogen Assessment in Amended Mining Soils Sown with Coronilla juncea and Piptatherum miliaceum

Metalliferous mining activities generate a large amount of waste. This waste usually has high concentrations of pollutants such as metal(oid)s associated with the extractive processes, which, if not properly treated and reclaimed, put the ecosystem and the population at risk. One of the most used techniques for mine waste reclamation is aided phytostabilization, which is based on the use of plants that immobilize metals in the soil/roots aided by the use of amendments to improve the soil properties to favor plant growth. Although amendments increase nutrients and improve the soil properties, the concentration of these nutrients—especially N, the most limiting plant nutrient—decreases over time. Thus, this study focused on the evaluation of the relationship between different combinations of amendments (compost, biochar, zeolite and limestone) and plant growth (we introduced Coronilla juncea and Piptatherum miliaceum) on the evolution of soil N over time as well as the influence of C. juncea on soil N fixation. The results showed that the addition of amendments improved the soil characteristics in all plots favoring the growth of C. juncea and P. miliaceum. The compost provided higher concentrations of total N, nitrites, nitrates and ammonium due to the nature of this amendment and the biochar was less in measure. The limestone helped to elevate the pH and the zeolite controlled the exchangeable ions. Soils from C. juncea showed higher concentrations of N forms, suggesting that this legume contributes to the enrichment of soil N, likely due to biological fixation. Hence, the combinations limestone-zeolite-compost and limestone-zeolite-compost-biochar were the most suitable treatments for improving the soil fertility and favored plant growth. In addition, C. juncea seems to be a good candidate for reclaiming mining environments.

Molecular Characterization of Free Living N2 Fixing Bacteria Isolated from Agricultural Soils of North Gujarat, India

Background: Molecular identification of a wide range of organisms capable of carrying out biological nitrogen fixation (BNF) are diverse in nature and significantly improves plant growth. Biological N2 fixation reflects the activity of a phylogenetically diverse list of microorganisms. Molecular characterization provides efficient means to identify organisms with the potential of N2 fixation. Applying these techniques in an array of environments has considerably broadened our understanding of the suite of organisms that can carry out BNF. Methods: Thirty-four strains of free living N2 fixing bacterial strains were isolated from diverse plants cultivated in North Gujarat, including wheat, cotton, castor and pearl millet, using a nitrogen-free selective medium. Acetylene reduction assay was used to check the ability of all bacteria to fix nitrogen. Hybridization with nifH probe derived from Azotobacter vinelandii with isolated free-living nitrogen-fixing bacteria showed a positive result. The selected strains were characterized by molecular analysis like; ARDRA and 16S rDNA sequencing. Result: Based on molecular characterization 17 strains to known groups of nitrogen-fixing bacteria, including organisms from the genus Azotobacter, Pseudomonas, Enterobacter, Arthrobacter, Bacillus, Variovorax, Nocardiodies, Rhodococcus, Mycobacterium, Planococcus, Microbacterium have been identified. One of the strains was identified as unknown bacteria. The potential strains were identified by 16srDNA analysis and also corroborated by morphological and biochemical characterization.

Clinical Results in Posterior-Stabilized Total Knee Arthroplasty with Cementless Tibial Component in Porous Tantalum: Comparison between Monoblock and Two Pegs vs. Modular and Three Pegs

Nowadays, total knee arthroplasty (TKA) is widely considered to be the gold standard for treatment of end-stage knee osteoarthritis. Although the optimal mode of fixation in TKA continues to be an important area of investigation, cementless fixation offers the possibility to gain biologic fixation, preserve bone stock and mineral density, and potentially improve survivorship. The purpose of this retrospective study was to evaluate the clinical results of a posterior-stabilized total knee arthroplasty with cementless tibial component in porous tantalum, comparing two groups: Group A (30 patients), TKA with a monoblock component and two pegs, and Group B (22 patients), with a modular component and three pegs. Knee Society Score (KSS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) were submitted to the patients, and radiographs were collected at the last follow-up. The mean follow-up was 26.32 (20–40) months. Significant differences were not detected between the postoperative KSS values in the two groups (p = 0.44). Evaluating KOOS outcomes, we found in Group A that the rating system showed a statistically significant improvement from a preoperative average rating of 51.4 (SD ± 15) to an average of 72.66 (SD ± 19) at final follow-up (p < 0.05). In Group B, the KOOS rating system showed a statistically significant improvement from a preoperative average rating of 48.3 (SD ± 18) to an average of 79.54 (SD ± 17) postoperatively (p < 0.05). Comparing KOOS final outcomes between groups, we found no statistically significant difference at the mean final follow-up (p = 0.20), with the exception of the sport-related section (p < 0.05). Radiological evaluation at the final follow-up did not show any sign of polyethylene wear, radiolucency, septic or aseptic loosening, or change in alignment in either group. The current study demonstrates an excellent survivorship of cementless tibial components in porous tantalum and the possibility of osseous integration, without significant differences between the two groups under investigation.

Combined acetabular and femoral neck fractures with intrapelvic femoral head dislocation: Successful staged management of a rare injury in two cases.

Combined central acetabular and femoral neck fractures with intrapelvic femoral head dislocation is an infrequent situation that provides a problematic condition for surgeons attempting to reconstruct the hip joint. Herein, we report two cases involving central acetabular fracture-dislocation combined with intrapelvic dislocation of a fractured femoral neck. Each case involved associated injuries that made primary total hip arthroplasty (THA) impossible and necessitated using the fewest skin incisions possible. As a result, we first attempted a posterior acetabular fixation of both the anterior and posterior columns with intra-articular plating of the anterior column. Finally, a cementless acetabular cup was implanted. There were no complications identified during the stages of reconstruction up to and including THA. The two patients̓ final Harris Hip scores were 98 for the first patient (at five years), and 91 for the second patient (at 1 ½ years). In conclusion, staged reconstruction of the hip joint with intra-articular acetabular plating does not weaken the acetabular bone that can accept insertion of THA with cementless biological acetabular fixation without complications and with an acceptable clinical outcome up to five years.

Biofixation of CO2 from a power plant through large-scale cultivation of Spirulina maxima

Using microalgae for biological fixation of CO2 is an attractive option for limiting the amount of CO2 emissions from power plants. In this experiment, Spirulina maxima was successfully grown utilizing direct flue gas emitted from the Ratchaburi Electricity Generating Company Limited, Thailand. The aims of this study were to determine the optimal conditions for large-scale culturing of this alga for maximum biomass as well as CO2 abatement. The results showed that the carbon source of NaHCO3 can be reduced from standard Zarrouk medium of 16.8 down to 8 g/L, producing fresh and dry weight biomass yields of 206 and 21.57 kg, respectively, within 30 days of cultivation. The optimal initial pH was 9.0, thereby reducing the lag phase of algal growth and producing the best fresh weight yield. The natural light intensity (with CO2) prevented stressed and weakened the algal cells, resulting in extending the algal life and producing the highest yields of fresh and dry weight. The morphology of algal cells was examined following culturing at pH 9 and pH10.5. The algal cells produced at pH 9 had a helical shape of the trichome, a separate septum and thylakoids, and the vacuoles were distributed throughout the cell, while algal cells cultured in medium with an initial pH of 10.5 mostly had the straight form, with the septum and thylakoids being unclear. The maximum CO2 level used was 2.5 times base level of the CO2 (141.75 g CO2/h) produced the highest biomass of fresh and dry weights. The optimal culture for CO2 gas was the continuous culture system and using CO2 efficiently, which encouraged algal growth and produced higher biomass yields than those from the batch culture system. There was no significant difference in nutritional value terms for the protein and pigments contents between the algal biomass products in assay with and without CO2 Furthermore, there was no metal contamination in algal biomass. The results indicate that the use of waste CO2 from a power plant can be successfully used for large-scale Spirulina production.

The porous coating of joint implants as a factor of their stable fixation

To ensure effective biological fixation of the newly designed cementless hip joint implant, a macroporous material proposed to be used as a coating for the implant was studied. Eighty-five samples of the cylindrical implants produced via hot sintering from spherical titanium granules having different diameters were analyzed. Morphological, mechanical, and other findings revealed a rapid bone ingrowth into the sample pores and their firm biological fixation in the canine tubular bone. The selected material having optimal characteristics will be applied to the surface of the specially designed joint implant. Its pilot-designed model is manufactured to make initial clinical trials, followed by updating for applying the ball coating. The new joint implant macroporous coating with its improved geometry will enhance the fixation of the construction due to bone ingrowth, contribute to the rapid postoperative recovery of a patients full-load walking ability, and minimize the risk for aceptic loosening of the implant.

FUNCTIONAL OUTCOME OF PRE-CONTOURED MEDIAL LOCKING COMPRESSION PLATE USING MIPO (MINIMaAL INVASIVEPLATING OSTEOSYNTHESIS) TECHNIQUE IN TREATMENT OF DISTAL TIBIAL FRACTURES

Introduction:- The management of distal tibial fractures remains challenging due to subcutaneous location of larger portion of tibia,paucity of soft tissue coverage and precarious blood supply of distal leg.Conservative management may be complicated by loss of reduction and subsequent malunion. MIPO (Minimal invasive plating osteosynthesis) has evolved as a newer concept to treat distal tibial fractures. It works on Biological fixation principle which assists physiological process of bone healing wisely with minimal operative intervention. Methods:- Prospective follow up study carried out at J.L.N. Medical College Ajmer from 1 Jan 2017 to 30 June 2018. 30 patients with distal tibial fractures were included and operated with pre-contoured medial locking compression plate using MIPO technique. Fractures were classified as per AO system and patients were followed and scored according to TEENY and WISS scoring criteria. Results:- Functional results according to TEENY and WISS scoring criteria was found excellent in 9 (30%), good in 16(53.33%), Fair in 3(10%) and poor in 2 (6.66%) patients. Poor outcome occurs due to development of complications Conclusion:-Internal fixation of distal tibial fractures with pre-contoured medial locking compression plate using MIPO technique is effective and safe and provides more stable construct with anatomical reduction.

Nitrogen transfer from legume green manure in a crop rotation to an onion crop using 15N natural abundance technique

Legumes as green manure allow adding N from the air to the soil through their biological fixation. The objective was to evaluate the effect of legume crops as green manure at the beginning of the rotation on soil quality and their N input to the following onion crop (Allium cepa L. var. cepa). Five crops were sown: faba-bean (Vicia faba L.), field pea (Pisum sativum L.), oat-vetch mixture (Avena sativa L. + Vicia atropurpurea Desf.), white lupin (Lupinus albus L.), and oat as control treatment, with four replicates. Prior to sowing soil was prepared with 20 Mg ha-1 compost and 715 kg ha-1 rock phosphate. Then, at 50% grain filling stage these crops were incorporated as green manure to the soil, followed by the onion crop. Biological N fixation (BNF) by 15N natural abundance technique parameters of green manure, yield, leaf N content of the legumes and onion, and soil bio-physicochemical properties were measured and analyzed by ANOVA and Tukey’s test for mean separation (P ≤ 0.05). Faba-bean treatment had the highest BNF (388 and 369 kg N ha-1 fixed in 2017 and 2018, respectively). For onion yield, just faba-bean and oat-vetch in 2018 reached the Chilean mean yield with 54.39 and 49.08 Mg ha-1, respectively. Control treatment yield was not significantly different. Leaf N content in onion remained within a normal range in all treatments. Adding green manure together with compost to the soil improved soil N and K contents.

Biofertilizing Effects of Anabaena cylindrica Biomass on the Growth and Nitrogen Uptake of Wheat

ABSTRACT There are a substantial number of studies on the biofertilization effects of cyanobacteria in rice paddy fields, mainly attributed to biological fixation of N2, but not much attention has been given to their fertilizing capacity in aerobic soils. Few studies have used solid media (i.e. a soil) when testing the plant-growth-promoting effects of microalgae on plants, and particularly on wheat. The purpose of this study was to test the biofertilizing effect of a filamentous cyanobacterium, previously isolated from an agricultural soil, in order to evaluate the potential substitution of chemical fertilizers and to test its phyto-stimulating capacity. Seedlings of Triticum aestivum were grown in pots with a peat-vermiculite mixture (1:1 weight basis) in an experiment designed as a complete randomized block, consisting of four treatments and with four replicates each: a pure culture of Anabaena cylindrica concentrated by centrifugation to 2 g dry matter L−1 (treatment B); spent cyanobacteria growth medium filtered at 0.22 µm (treatment F); harvested cyanobacterial mat re-suspended in distilled water (treatment WB); and distilled water as a control (treatment W). Aboveground wheat plant mass was improved by 40% in both treatments with cyanobacterial biomass (B and WB), as compared to the control (W) and filtrate (F), demonstrating that the co-cultivation with living cyanobacterial biomass was key to plant improvement. Chlorophyll contents were also increased by nearly 50% and nitrogen by over 10% in the treatment WB, clearly indicating that nutrients in the filtrate were irrelevant to the beneficial effects on plant growth.

Mixture of N2-fixing tree species promotes organic phosphorus accumulation and transformation in topsoil aggregates in a degraded karst region of subtropical China

Many studies have shown that introducing N2-fixing tree species into plantations can increase soil nitrogen (N) availability, via biological N2 fixation and faster N cycling. However, the effects and regulatory mechanisms of N2-fixing tree species in planting single species vs a combination of two species on phosphorus (P) accumulation and transformation in degraded karst soils remain poorly understood and appear site-dependent. This study aimed to determine the effects of introducing N2-fixing tree species (via single species vs a combination of two species) into a degraded karst region on organic phosphorus (Po) accumulation and transformation in topsoil aggregates. A comparative experiment was performed involving 8-year-old pure plantations of Dalbergia odorifera (PD) and Acrocarpus fraxinifolius (PA), a mixed plantation of Dalbergia odorifera and Acrocarpus fraxinifolius (MP), and an adjacent natural weed field (no trees, CK) in Mashan, Guangxi, subtropical China. The results showed that the contents of soil organic carbon (SOC), nitrate nitrogen (NO3−-N), available phosphorus (AP) and C:N ratios in bulk soil and aggregates, increased significantly (P < 0.05) in MP compared to CK. The levels of soil microbial biomass N (MBN) and microbial biomass P (MBP) in bulk and aggregate soils increased significantly (P < 0.05), except for micro-aggregates (<0.25 mm) in MP samples. In contrast, no significant differences of MBN or MBP were found among PD, PA and CK plots in bulk and most aggregate soils. The phospholipid fatty acid (PLFA) contents of all microbes, bacteria, fungi, arbuscular mycorrhizal (AM) fungi and actinomycetes were also significantly higher (P < 0.05) in MP than those in CK and PD in bulk and most aggregate soils. Labile Po and highly resistant Po, and the activities of all tested N and P hydrolytic enzymes, improved in bulk soil and most aggregate size classes in all forest types, especially in MP samples. Finally, redundancy analysis (RDA) indicated that Po fractions were primarily driven by alkaline phosphatase (ALP), MBN and AM. Our findings suggest that introducing N2-fixing tree species (especially MP) may be an effective method for increasing N availability and AM colonization of roots, and thereby promoting Po accumulation and transformation in degraded karst regions of southwest China.

Dehydrated UiO‐66(SH)2: The Zr−O Cluster and Its Photocatalytic Role Mimicking the Biological Nitrogen Fixation

AbstractThis work reports the dehydrated Zr‐based MOF UiO‐66(SH)2 as a visible‐light‐driven photocatalyst to mimic the biological N2 fixation process. The 15N2 and other control experiments demonstrated that the new photocatalyst is highly efficient in converting N2 to ammonia. In‐situ TGA, XPS, and EXAFS as well as first‐principles simulations were used to demonstrate the role of the thermal treatment and the changes of the local structures around Zr due to the dehydration. It was shown that the dehydration opened a gate for the entry of N2 molecules into the [Zr6O6] cluster where the strong N≡N bond was broken stepwise by μ‐N−Zr type interactions driven by the photoelectrons aided by the protonation. This mechanism was discussed in comparison with the Lowe–Thorneley mechanism proposed for the MoFe nitrogenase, and with emphasis on the [Zr6O6] cluster effect and the leading role of photoelectrons over the protonation. The results shed new light on understanding the catalytic mechanism of biological N2 fixation and open a new way to fix N2 under mild conditions.

Dehydrated UiO‐66(SH)2: The Zr−O Cluster and Its Photocatalytic Role Mimicking the Biological Nitrogen Fixation

AbstractThis work reports the dehydrated Zr‐based MOF UiO‐66(SH)2 as a visible‐light‐driven photocatalyst to mimic the biological N2 fixation process. The 15N2 and other control experiments demonstrated that the new photocatalyst is highly efficient in converting N2 to ammonia. In‐situ TGA, XPS, and EXAFS as well as first‐principles simulations were used to demonstrate the role of the thermal treatment and the changes of the local structures around Zr due to the dehydration. It was shown that the dehydration opened a gate for the entry of N2 molecules into the [Zr6O6] cluster where the strong N≡N bond was broken stepwise by μ‐N−Zr type interactions driven by the photoelectrons aided by the protonation. This mechanism was discussed in comparison with the Lowe–Thorneley mechanism proposed for the MoFe nitrogenase, and with emphasis on the [Zr6O6] cluster effect and the leading role of photoelectrons over the protonation. The results shed new light on understanding the catalytic mechanism of biological N2 fixation and open a new way to fix N2 under mild conditions.

EXPERIMENTAL STUDY OF OSTEOSYNTHESIS STABILITY OF THE DISTAL PART OF THE HUMERUS

Unresolved issue is improving of the osteosynthesis of extraarticular fractures of the distal humerus. Search for a simplified method of biological fixation, which assumes, with low trauma, to ensure the stable fixation of fragments and movements in the elbow joint in the early postoperative period. Objective.To carry out a comparative analysis of the bone fragments displacement of the distal humerus in extra-articular fractures, stabilized by extraosseous and transosseous osteosynthesis. Methods. Biomechanical study of the distal humerus model was made. Transosseous osteosynthesis was modeled using the author’s external fixation apparatus (EFA). For comparison, we chose an osteosynthesis with a Y-shaped plate. The humeral models were loaded with an interval and a stepwise increased in the load for compression along the axis, flexion in a parallel plane, as well as perpendicular to the fixing elements of the plate and EFA. The magnitude of the load gradually increased from 0 to 250 N with a step of 50 N. The magnitude of the forces at which, due to the action of various loads, a displacement at the level of the fracture appeared. Results. The analysis of experimental studies showed that the rod apparatus and the plate provide the same stability of fixation of the fragments of the humerus under conditions of axial compression load (p &gt; 0.05). Under the influence of bending loads of more than 100 N in a plane parallel to the fixing elements, the plate had a slight advantage (10 %). A significantly better result (p &lt; 0.01) was obtained when an external device was used under the action of bending loads in a plane perpendicular to the fixing elements. Conclusions. In the case of fractures of the distal humerus, the transosseous osteosynthesis using the proposed external fixation rod device ensures the stability of the fragments under all loading options. It is quite reliable and can be recommended for use in clinical practice.

Clinical and Radiographic Outcomes of Novel 3D-Printed Highly Porous Knee Cone Design.

Metaphyseal bone defects seen at revision total knee replacement (TKA) have traditionally been treated with bone graft or cement. Recently, metal augments have surfaced as viable alternatives to conventional methods previously used in these patients. Newer 3D-printed metal cones offer better biological fixation as a means of improving construct stability. This study aimed to determine clinical and radiographic outcomes of the novel 3D-printed titanium cone augments for femoral and tibial metaphyseal bone defects. A retrospective review was undertaken of 72 patients who underwent revision TKA with metaphyseal cones (Stryker) and stemmed implants from 2015-2017. Knee Injury and Osteoarthritis Outcome Scores (KOOS Jr) and VR/SF-12 scores were recorded. Knee Society radiographic scores were calculated at latest follow up to evaluate for radiolucency and biological fixation. Loosening noted on radiographs and reoperation for any reason were the endpoints to determine survivorship. A total of 68 patients with 78 cones (58 tibial, 20 femoral) met inclusion criteria. Mean follow up was 3.4 years (range 2-5.4 years). The average KOOS Jr score increased from 38 preoperatively to 66 at two years. The average VR/SF-12 PH score increased from 33 preoperatively to 37 at two years. The average VR/SF-12 MH score increased from 46 preoperatively to 54 at two years. Twelve percent of tibial implants and 10% of femoral implants with cones were found to have lucency in at least one radiographic zone. Overall survivorship at latest follow up was 93% with two patients requiring revision for infection, two revised following mechanical complications, and one patient who underwent polyethylene exchange after experiencing mechanical complications. When considering only aseptic loosening, survivorship was 100%. This 3D-printed titanium femoral and tibial cone augment system showed excellent survivorship, biological fixation, clinical outcomes, and radiographic outcomes in the setting of TKA. Further studies are needed for assessment of long-term survivorship.

Nitrogen Budget and Statistical Entropy Analysis of the Tiber River Catchment, a Highly Anthropized Environment

Modern farming causes a decline in the recycling of the soil’s inorganic matter due to losses by leaching, runoff, or infiltration into the groundwater. The Soil System Budget approach was applied to evaluate the net N budget at the catchment and sub-catchment levels of the Tiber River (central Italy) in order to establish the causes for different N budgets among the sub-catchments. Statistical Entropy Analysis (SEA) was used to evaluate the N efficiency of the Tiber River and its sub-catchments, providing information on the dispersion of different N forms in the environment. The total N inputs exceeded the total outputs, showing a low N retention (15.8%) at the catchment level, although some sub-catchments showed higher N retention values. The Utilized Agricultural Area was important in the determination of the N balance, as it was linked to zoo- and agricultural activities, although the Random Forest analysis showed that the importance ranking changed with the land use. The low N retention of the Tiber catchment was due to the soil characteristics (Cambisols and Leptosols), loads from atmospheric deposition, biological fixation, and the livestock industry. The SEA simulations showed a reduction of the N released into the atmosphere and groundwater compartments from 34% to 6% through a reduction of the N loads by 50%.

A cell-free self-replenishing CO2-fixing system

Biological CO2 fixation is so far the most effective means for CO2 reduction at scale and accounts for most of the CO2 fixed on Earth. Through this process, carbon is fixed in cellular components and biomass during organismal growth. To uncouple CO2 fixation from growth and cellular regulation, cell-free CO2 fixation systems represent an alternative approach since the rate can be independently manipulated. Here we designed an oxygen-insensitive, self-replenishing CO2 fixation system with opto-sensing. The system comprises a synthetic reductive glyoxylate and pyruvate synthesis (rGPS) cycle and the malyl-CoA-glycerate (MCG) pathway to produce acetyl-coenzyme A (CoA), pyruvate and malate from CO2, which are also intermediates in the cycle. We solved various problems associated with the in vitro system, and implemented opto-sensing modules to control the regeneration of cofactors. We accomplished sustained operation for 6 hours with a CO2-fixing rate comparable to or greater than typical CO2 fixation rates of photosynthetic or lithoautotrophic organisms.

Enhanced osseointegration of 3D-printed cementless tibial prostheses with trabecular metal surfaces in a novel three-partition design

Compared with cemented implants in total knee arthroplasty (TKA), cementless prostheses can provide better biological fixation for young and active patients by their osseointegration with host bone. However, to date, early loosening occurs in most cementless knee prostheses due to extensive bone ingrowth deficiencies, especially at the tibial bone-prosthesis interfaces. This study aims to improve the osseointegration capability of 3D-printed cementless tibial prostheses by modifying metal surfaces with a three-partition trabecular-like porous structure. Ti6Al4V tibial prostheses were prepared with a novel three-partition trabecular surface design by electron beam melting (EBM) according to the regional structural and mechanical properties of human tibial plateaus. The trabecular prostheses were implanted in the knee joints of sheep in situ to evaluate the osseointegration and stability of the designed tibial implants. X-ray images and anatomical observation showed no detachment or displacement of the trabecular implants at 3 and 6 months postoperation. Micro-CT evaluation and histological analysis showed improved osseointegration and strengthened biological fixation of the trabecular implants. The cellular experiment results indicated that three topological types of porous scaffolds corresponding to the three-partition trabecular prosthesis design were favorable for the proliferation and differentiation of preosteoblasts. In conclusion, a novel three-partition trabecular surface design enhanced the osseointegration capacity of 3D-printed Ti6Al4V tibial implants, which will promote the application of cementless knee prostheses in clinics.

Bone Ongrowth of Contemporary Cementless Tibial Components: ARetrieval Analysis.

BackgroundCementless total knee arthroplasty is gaining interest as total knee arthroplasty patients become younger, more active, and interested in long-term biologic fixation. New porous coatings have altered mechanical properties to improve bone osseointegration, although limited data exist on this topic. We measured the bone ongrowth on retrieved tibial trays to determine how demographic, radiographic, or implant design factors correlate with ongrowth.Material and methodsTwenty retrieved trays were assessed from 3 designs: Zimmer NexGen Trabecular Metal (n = 9), Stryker Triathlon Tritanium (n = 6), and Biomet Vanguard Regenerex (n = 5). Exclusion criteria included revision for aseptic loosening or early postoperative infection. Ongrowth on the tibial components and on corresponding pegs (if accessible) was assessed. The amount of osseointegration was reported as the bone directly opposed to the surface divided by the available area for ongrowth. Radiographs were reviewed for alignment and regions of biologic fixation.ResultsBone ongrowth covered 65% ± 19% of the tibial tray surface and did not differ among manufacturers (P = .27). Medial pegs had less ongrowth than lateral pegs (39% vs 64%, P = .02). Vanguard medial pegs had less ongrowth than NexGen medial pegs (15% vs 61%, P = .03). Length of implantation was different between the NexGen (55 months) and Triathlon (24 months, P < .05) design only. Patient and radiographic data demonstrated no correlation with ongrowth.ConclusionAn average 65% of the porous tibial tray surface had ongrowth at revision. These values are consistent with manufacturing claims for excellent bone ongrowth for newer porous coatings.

Linkage of Crop Productivity to Soil Nitrogen Dynamics under Biochar Addition: A Meta-Analysis across Field Studies

Biochar addition is a promising solution to improve soil nitrogen (N) availability and enhance crop productivity. However, a comprehensive understanding of the impact of soil N dynamics on crop productivity under biochar addition remains elusive. Here, we conducted a meta-analysis from 93 peer-reviewed field experiments to synthesize the linkage of crop productivity to soil N dynamics under biochar addition. The results show that biochar addition significantly enhanced crop productivity by 12.8% and plant N uptake (PNU) by 22.6%, and there was a strongly positive relationship between crop productivity and PNU. Biochar addition also significantly increased the contents of soil total N (TN), inorganic N (IN), microbial biomass N (MBN), and biological N2 fixation (BNF) by 3.34–18.7%, but reduced nitrous oxide (N2O) emission by 15.9%. Further analysis with the aggregated boosted tree model indicated that the TN and BNF played the most important roles in biochar-induced change in crop productivity. However, while crop productivity was positively correlated with TN under biochar addition, it showed a negative correlation with BNF. These findings suggest that biochar addition could enhance crop growth and productivity through increasing the soil N resource and N uptake, but this was not true for some N2-fixing crops, probably because they were usually constrained by nutrients other than N.

Integrated Approach for Carbon Sequestration and Wastewater Treatment Using Algal–Bacterial Consortia: Opportunities and Challenges

Increasing concentrations of carbon dioxide (CO2), one of the important greenhouse gases, due to combustion of fossil fuels, particularly burning coal, have become the major cause for global warming. As a consequence, many research programs on CO2 management (capture, storage, and sequestration) are being highlighted. Biological sequestration of CO2 by algae is gaining importance, as it makes use of the photosynthetic capability of these aquatic species to efficiently capture CO2 emitted from various industries and converting it into algal biomass as well as a wide range of metabolites such as polysaccharides, amino acids, fatty acids, pigments, and vitamins. In addition, their ability to thrive in rugged conditions such as seawater, contaminated lakes, and even in certain industrial wastewaters containing high organic and inorganic nutrients loads, has attracted the attention of researchers to integrate carbon capture and wastewater treatment. Algae offer a simple solution to tertiary treatments due to their nutrient removal efficiency, particularly inorganic nitrogen and phosphorus uptake. The algal–bacterial energy nexus is an important strategy capable of removing pollutants from wastewater in a synergistic manner. This review article highlights the mechanism involved in biological fixation of CO2 by microalgae, their cultivation systems, factors influencing algal cultivation in wastewater and CO2 uptake, the effect of co-cultivation of algae and bacteria in wastewater treatment systems, and challenges and opportunities.