Retention Of Structures Research Articles

Cobalt(I) and Nickel(II) Complexes of Bis(1,3‐diphosphacyclobutadiene) Sandwich Anions

AbstractComplexes [(C4Me4)Co(CO)2{Co(P2C2tBu2)2}] (1, C4Me4 = tetramethylcyclobutadiene) and [CpNi{Co(P2C2tBu2)2}(PPh3)] (2, Cp = cyclopentadienyl) were synthesized by transmetalating [Tl(thf)2{Co(P2C2tBu2)2}] with [(C4Me4)Co(CO)2I] and [CpNiBr(PPh3)]. Compounds 1 and 2 were fully characterized by X‐ray crystallography, multinuclear NMR, UV/Vis, and IR spectroscopy, and elemental analysis. Their molecular structures show σ‐coordination of one phosphorus atom of the [Co(P2C2tBu2)2]– anion to the second metal atom (cobalt or nickel). Time‐dependent density functional theory (TD‐DFT) calculations were applied to gain insight into the electronic structures and the nature of the electronic transitions observed in the UV/Vis spectra. Cyclic voltammetry studies revealed the similar redox behavior of 1 and 2, which are reversibly oxidized to the corresponding monocations 1+ and 2+ with retention of the dinuclear structures. The cyclic voltammograms furthermore show that 1 and 2 decompose upon reduction with cleavage of the dinuclear structures into the free [Co(P2C2tBu2)2]– anion and further uncharacterized products.

Iodine Treatment of Lignin–Cellulose Acetate Electrospun Fibers: Enhancement of Green Fiber Carbonization

Pure biopolymer-based electrospun precursor carbon fibers are fabricated using an abundant and inexpensive biopolymer lignin blended with renewable resource-based cellulose acetate (CA). Iodine treatment on the fabricated green fiber was successfully performed in order to enhance the carbonization process as well as the retention of fiber morphology. The absorption mechanism of iodine by lignin and cellulose acetate and their derived electrospun green fibers has been investigated by means of thermal behavior and morphological retention. It was found that iodine treatment plays a vital role in altering the graphitization behavior as well as morphology retention during the carbonization process. With the help of iodine treatment, the green precursor fibers were successfully converted into thin carbon fibers, and scanning electron microscopy analysis confirmed the retention of fibrous structures with diameters around 250 nm. Raman spectroscopy revealed that although the overall level of graphitization was lower compared to polyacrylonitrile-based fibers, the graphitic crystallite size was larger in the produced carbon fibers. The produced pure biopolymer fibers and iodine treatments show promise for the production of green and cost-reduced carbon fibers.

Refurbishment of structures on the Manchester Metrolink phase 3

The Metrolink phase 3 project in Manchester, UK, has created around 60 km of new tram lines and has incorporated over 380 structures including 160 bridges and tunnels. Nearly 80 bridges were refurbished, repaired or strengthened to provide a low-maintenance system with a minimum 50-year structural design life. The new tram lines have been built on new dedicated alignments and on former railway corridors, reusing existing structures with an age of up to 140 years. Various contractual and technical approaches were taken to address the risk due to structure condition, including risk-sharing arrangements and phased scope determination. Particular issues encountered by the project include: limited information on structure condition; corrosion of metallic structures; scope risk; strategy for repair versus replacement; vehicle incursion risk; determining appropriate specifications; retention of cast-iron structures and modifications to parapets due to electrification. The conclusions include lessons learned for projects dealing with the renewal and upgrade of legacy structures in an affordable manner.

Molten globule-like partially folded state of Bacillus licheniformis α-amylase at low pH induced by 1,1,1,3,3,3-hexafluoroisopropanol.

Effect of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) on acid-denatured Bacillus licheniformis α-amylase (BLA) at pH 2.0 was investigated by far-UV CD, intrinsic fluorescence, and ANS fluorescence measurements. Addition of increasing HFIP concentrations led to an increase in the mean residue ellipticity at 222 nm (MRE222 nm) up to 1.5 M HFIP concentration beyond which it sloped off. A small increase in the intrinsic fluorescence and a marked increase in the ANS fluorescence were also observed up to 0.4 M HFIP concentration, both of which decreased thereafter. Far- and near-UV CD spectra of the HFIP-induced state observed at 0.4 M HFIP showed significant retention of the secondary structures closer to native BLA but a disordered tertiary structure. Increase in the ANS fluorescence intensity was also observed with the HFIP-induced state, suggesting exposure of the hydrophobic clusters to the solvent. Furthermore, thermal denaturation of HFIP-induced state showed a non-cooperative transition. Taken together, all these results suggested that HFIP-induced state of BLA represented a molten globule-like state at pH 2.0.

Self-assembly of cobalt(ii) and zinc(ii) tetranitrooctaethylporphyrin via bidentate axial ligands: synthesis, structure, surface morphology and effect of axial coordination

A series of remarkably stable supramolecular architectures of cobalt(II) and zinc(II) tetranitrooctaethylporphyrins (tn-OEP) mediated by long and conjugated bipyridyl axial ligands (L) have been synthesized in one pot in excellent yields and structurally characterized. Linear 1D polymeric chains were observed in the X-ray structures of the six-coordinated Co(II) complexes in which all the porphyrin units are aligned parallel to each other to have so-called “shish kebab” like architectures in order to maintain offset-stacked overlap. In contrast, ZnII(tn-OEP) forms five-coordinate porphyrin dimers [ZnII(tn-OEP)]2·L with “wheel-and-axle” like architectures which are then self-aggregated in a perpendicular manner to fill space more effectively. The surface patterns of the polymeric molecules on HOPG surface are found similar as observed in the X-ray structures. Large downfield shift and the peak broadening of the axial ligand resonances in solution are discerned in the 1H NMR of [CoII(tn-OEP)]·L which is due to the contiguity to the paramagnetic Co(II) center. In contrast, upfield shift of the 1H NMR resonances of the axial ligand L are observed for [ZnII(tn-OEP)]2·L due to the shielding effect of porphyrin ring current which confirms the retention of the solid state structures in solution. However, the axial ligation with monodentate pyridine to CoII(tn-OEP) produces six-coordinate complex [CoIII(tn-OEP)(py)2]+ in which Co(II) spontaneously oxidizes to Co(III) in air. The first 1e-reductive response in cyclic voltammetry of [CoIII(tn-OEP)(py)2]+, which is assigned as CoIII/CoII, has been shifted to −0.42 V which explains why addition of pyridine to CoII(tn-OEP) in air results in spontaneous oxidation of Co(II) to Co(III). Weaker ligand field strength of bidentate bipyridyl axial ligand L compared to its smaller monodentate counterpart pyridine has also been demonstrated here.

Investigation of Shape Retention of Inflatable Structures Based on Experiments and Fluid-Structure Interaction Analysis

Inflatable structures are widely used in aerospace engineering. They should keep a certain configuration in service, and their mechanical properties are closely related to their configurations. It is essential to investigate the ability of maintaining configuration of inflatable structures in order to study their mechanical properties . The concept of shape retention was first proposed in this paper. Besides, a shape retention index which quantitatively depicts the concept was given for inflatable column structures. The index takes compressive deformation and compression force into account. It is demonstrated that the shape retention increases with the increase of the modulus of the membrane and the inner pressure of inflatable structures.

Implantable Three-Dimensional Salivary Spheroid Assemblies Demonstrate Fluid and Protein Secretory Responses to Neurotransmitters

Radiation treatment in patients with head and neck tumors commonly results in hyposalivation and xerostomia due to the loss of fluid-secreting salivary acinar cells. Patients develop susceptibility to oral infections, dental caries, impaired speech and swallowing, reducing the quality of life. Clinical management is largely unsatisfactory. The development of a tissue-engineered, implantable salivary gland will greatly benefit patients suffering from xerostomia. This report compares the ability of a 2.5-dimensional (2.5D) and a three-dimensional (3D) hyaluronic acid (HA)-based culture system to support functional salivary units capable of producing fluid and phenotypic proteins. Parotid cells seeded on 2.5D, as well as those encapsulated in 3D HA hydrogels, self-assembled into acini-like structures and expressed functional neurotransmitter receptors. Structures in 3D hydrogels merged to form organized 50 μm spheroids that could be maintained in culture for over 100 days and merged to form structures over 500 μm in size. Treatment of acini-like structures with the β-adrenergic agonists norepinephrine or isoproterenol increased granule production and α-amylase staining in treated structures, demonstrating regain of protein secretion. Upon treatment with the M3 muscarinic agonist acetylcholine, acini-like structures activated the fluid production pathway by increasing intracellular calcium levels. The increase in intracellular calcium seen in structures in the 3D hydrogel culture system was more robust and prolonged than that in 2.5D. To compare the long-term survival and retention of acini-like structures in vivo, cell-seeded 2.5D and 3D hydrogels were implanted into an athymic rat model. Cells in 2.5D failed to maintain organized acini-like structures and dispersed in the surrounding tissue. Encapsulated cells in 3D retained their spheroid structure and structural integrity, along with the salivary biomarkers and maintained viability for over 3 weeks in vivo. This report identifies a novel hydrogel culture system capable of creating and maintaining functional 3D salivary spheroid structures for long periods in vitro that regain both fluid and protein secreting functions and are suitable for tissue restoration.

Retention forestry and biodiversity conservation: a parallel with agroforestry

In forested landscapes two general management systems – retention forestry and agroforestry – have been proposed as potentially efficient components of landscape approaches to ease the conflict between biodiversity objectives and human needs. In two recent reviews, Gustafsson et al. (2012) and Lindenmayer et al. (2012) provide a global overview of current knowledge about the practice and ecological roles of retention forestry. A few years ago, Bhagwat et al. (2008) produced a similar review addressing the role of agroforestry in biodiversity conservation. Here we draw a parallel between research on the ecological effects of retention forestry and agroforestry. We argue that conservation science and practice would benefit from bridging these two separate fields and the experiences achieved. Gustafsson et al. (2012) defined retention forestry as “an approach to forest management based on the long-term retention of structures and organisms, such as live and dead trees and small areas of intact forests, at the time of harvest”. The retention approach is broadly applicable to tropical, temperate and boreal forests (Lindenmayer et al. 2012). Agroforestry is defined as “intentional management of shade trees with agricultural crops” (Bhagwat et al. 2008). The agricultural component of agroforestry systems may also consist of pasture (Mosquera-Losada et al. 2008). Agroforestry systems are widespread in the tropics but also relevant to temperate regions (e.g. Gordon Nature Conservation 4: 29–33 (2013)

Autopia’s End

Since the 1980s, Detroit’s historic building stock of automotive manufacturing facilities has mostly disappeared. Demolition, redevelopment, and abandonment have left little to mark the city’s twentieth-century history as the world capital of the automobile industry. Planning and policy making have been complicit by publicly subsidizing destructive redevelopment and by failing to advocate for retention or preservation of significant structures and complexes. Even today, Detroit’s leadership calls for the demolition of one of the city’s last remaining historic auto factories. This article surveys the disappearance of Detroit’s auto factories and documents the histories of three of the largest complexes: the Chrysler-Chalmers Plant, cleared for a redeveloped factory; the Cadillac Plant, cleared for a failed economic development project; and the Packard Plant, slowly abandoned over sixty years. The article calls for a revised theory and practice of preservation that accommodates the weak markets, imperfect conditions, and informal uses that characterize abandoned industrial buildings in shrinking cities.

SnO2@TiO2 double-shell nanotubes for a lithium ion battery anode with excellent high rate cyclability

SnO2@TiO2 double-shell nanotubes have been facilely synthesized by atomic layer deposition (ALD) using electrospun PAN nanofibers as templates. The double-shell nanotubes exhibited excellent high rate cyclability for lithium ion batteries. The retention of hollow structures during cycling was demonstrated.

Variation in elk response to roads by season, sex, and road type

AbstractDespite the near universal recognition that roads negatively affect wildlife, the mechanisms that elicit animal responses to roads are often ambiguous or poorly understood. We conducted a multi‐year, multi‐season study to assess the relative influence of roads on elk (Cervus elaphus) in a human‐dominated landscape in South Dakota. We evaluated the effects of habitat covariates including security cover, forage quality, distance to roads (primary, secondary, and tertiary), and visibility from roads at the home range scale. We radio‐collared 28 elk (21 adult females and 7 adult males) and calculated seasonal (winter, spring, summer, and autumn) utilization distributions (UDs). We assigned habitat covariates to use percentiles within the UDs (1% increments; from 1 to 98 percentiles) and used spatially explicit mixed linear regression to model the relationship between use percentile and habitat covariates. For each season and sex, we evaluated 15 candidate models and used Akaike's Information Criterion weights (ωi) to identify top‐ranking models. We plotted influential coefficients from these models with 95% confidence intervals to examine the magnitude of effects. Our analysis revealed fundamental differences in response to roads, by road type, between sexes, and across seasons. Male elk established home ranges near roads devoid of vehicle traffic in winter, spring, and autumn. In summer, coinciding with peak vehicle traffic levels, male elk reduced their use of habitat that was both visible from and close to primary roads. Female elk subherds similarly responded to primary roads in spring and autumn, during times of year when they were calving and mating, respectively. In spring and summer, female elk subherds selected habitat near roads that were closed to vehicle traffic. Forage quality and security cover were influential in the periphery (>50th use percentile) of elk home ranges, whereas road covariates were more influential towards the core of elk home ranges. This analysis further demonstrates the utility of visibility from road metrics and suggests that the retention of vegetation structures that screen visibility potential from roads could be important components of elk management strategies. © 2012 The Wildlife Society.

Universal Charge Quenching and Stability of Proteins in 1-Methyl-3-alkyl (Hexyl/Octyl) Imidazolium Chloride Ionic Liquid Solutions

This study reports pH dependent stability of protein dispersions of five common proteins, bovine serum albumin (BSA), human serum albumin (HSA), immunoglobulin (IgG), β-lactoglobulin (β-Lg), and gelatin-B (Gel-B), all having isoelectric pH, pI ≈ 5, in room temperature ionic liquid solutions of 1-methyl-3-alkyl (hexyl/octyl) imidazolium chloride (concentration 0-0.2% w/v). Molecular hydrophobicity index, (H-index = hydrophobicity/hydrophilicity) of these molecules spanned the range 0.43-0.87. Electrophoretic characteristics, surface tension data and hydrodynamic size information revealed that IL solutions provide dispersion stability owing to specific protein-IL binding which did not alter their pI values though their surface charge was considerably screened. Change in maximum (ζ(max)) and minimum (ζ(min)) zeta potential values observed at pH ~3 (maximum protonated state) and pH ~8 (maximum deprotonated state) could be described universally as function of IL concentration, c as Δζ(x) = [1 - exp(-ac)] where Δζ(x) is either |(ζ(max) - ζ(w))|/ζ(w) or |(ζ(min) - ζ(w))|/ζ(w), and ζ(w) is the corresponding value in water. Tensiometry data showed two major stages of protein-IL interactions: (i) for c < cmc of IL, the IL molecules selectively bind with imidazolium cation through electrostatic forces forming protein-IL (complex) and (ii) for c> cmc free IL-aggregates begin to form. Similarly, we can define Δγ(x) as either |(γ(max) - γ(w))|/γ(w) at pH 3 or |(γ(min) - γ(w))|/γ(w) at pH 8. Both Δζ(x) and Δγ(x) showed linear dependence with c, Δγ(min, max) (or Δζ(min, max)) = (1 - K(γ) (or K(ζ)) H-index), where the slopes K(ζ) and K(γ) defined intermolecular interactions. Hydrodynamic radii data revealed protein stabilization, circular dichroism spectra implied retention of secondary structures, and Raman spectra confirmed a marginal increase in water structure. Results concluded that selective binding of IL molecules to protein surface in the form of bilayer screen protein surface charge, thereby, contributing to its dispersion stability.

Characteristics and retention of luteal structures, extended postinsemination cycle, progesterone, and pregnancy-specific protein B in serum after human chorionic gonadotropin treatment of dairy cows

Our objectives were to determine characteristics (size, number, and stayability) of luteal structures formed in response to human chorionic gonadotropin (hCG) administered on d 7 after timed artificial insemination (AI) and the influence of hCG on returns to estrus and pregnancy outcome. Holstein cows (n=328), milked 3 times daily, previously inseminated at first service were assigned randomly to a completely randomized design consisting of 2 treatments when at least 1 corpus luteum (CL) was detected on d 7 after AI. Treatment consisted of 1,000IU hCG or 1mL of saline (control) administered i.m. Blood was collected and luteal structures were mapped and sized by transrectal ultrasonography on d 7, 14, 21, 28, and 32 after AI. Blood also was collected on d 60 in all pregnant cows. Treatment with hCG induced new luteal structures in 70% of cows, regardless of pregnancy status or number of pretreatment CL. Cows producing greater than the median 46kg of energy-corrected milk per day were less likely to respond to hCG. The number of total luteal structures per cow, original CL volume, and total luteal volume (original CL + new luteal structures) were increased by hCG. Progesterone concentration was greater in pregnant than nonpregnant cows on d 14 unless cows responded to hCG by forming new luteal structures. Concentrations of progesterone were greatest in pregnant, hCG-treated cows. Pregnancy per AI at d 32 or 60 after first AI was less in hCG- than saline-treated cows because pregnancy outcome for hCG cows that had only 1 pretreatment CL and failed to respond to hCG was only 55 to 61% of that observed in controls. Proportions of cows returning to estrus from 18 to 25d after AI were less in hCG than control cows but greater for cows returning >25d. Regardless of treatment, 25% of cows in both treatments retained at least 1 original CL to d 28 after AI and were not pregnant on d 32. Progesterone concentrations in these nonpregnant cows with retained CL between d 14 and 28 after AI were intermediate between nonpregnant cows that returned to estrus by d 25 and all pregnant cows. Concentrations of pregnancy-specific protein B were elevated in some of these nonpregnant, CL-retained cows, indicating early pregnancy loss. Retention of original luteal tissue in nonpregnant cows to d 28 after AI indicated that pregnancy had been initiated but failed, as verified by concentrations of progesterone and pregnancy-specific protein B.

Post-Laminectomy Spondylolisthesis - A Review of the Posterior Elements and their Contribution to the Stability of the Lumbar Spine

As surgical practice changes with increasing new evidence, a review of past experiences often gives us a good idea why we do things the way it is now. Our modern understanding of factors contributing to the stability of the lumbar spine can be represented using posterior decompression of the lumbar spine as an example. Since the late 1900s, the Christmas tree procedure gained widespread popularity in treating neurogenic claudication and lumbar stenosis. However, this clinical improvement is often transient and patients return with symptom recurrence and findings of spinal instability. Further biomechanical studies and clinical trials looked at modifications to this procedure such as facet sparing laminectomy and laminotomy with improved results. It was then that bony, discoligamentous and muscular factors are increasingly recognized as contributors to the overall stability of the lumbar spine. Surgical decompression of spinal stenosis has to balance between adequate removal of bone and soft tissue for an effective decompression of neural structures, and sufficient retention of bone and soft tissue structures to maintain mechanical stability of the spine. When these stabilizers are compromised, a prophylactic fusion of the spinal unit may be required. Ultimately, the decision to perform laminectomy or laminotomy has to be a clinical judgement based on a combination of surgeon, patient and disease factors.

Effects of repeated fertilization of young Norway spruce on foliar phenolics and arthropods: Implications for insectivorous birds’ food resources

Repeated fertilization of young forests is a promising concept to increase the production of wood fiber, but the consequences of intense fertilization regimes on forest birds and their food resources, mediated through changes in the foliar chemistry are inadequately known. We assessed the effects of repeated fertilization in stands of young Norway spruce (Picea abies) on foliar phenolics and arthropods in an intensively managed forest area in southern Sweden in relation to the abundance of arboreal feeding birds breeding in the same stands. We anticipated leaf-sucking arthropods (viz. Hemiptera (aphids)) to react more strongly to changes in foliar phenolics than other invertebrate groups. Overall, we found small effects of fertilization on abundance and composition of different groups of foliar arthropods. However, the abundance of Hemiptera was much higher in early spring in fertilized stands than in unfertilized stands, whereas mites (Anactinotrichida and Actinotrichida) were more abundant in late spring in the fertilized stands. On the contrary, springtails (Collembola) were more abundant in unfertilized stands than in fertilized stands the late spring. The concentrations of two of the most abundant phenolics (hydroxycinnamic acid derivatives) as well as the sum concentration of HPLC-phenolics, were consistently lower in the fertilized stands. Positive effects on arthropod abundance mediated trough changes in the foliar chemistry following fertilization could help to explain why resident Goldcrest (Regulus regulus), which feeds on folivorous arthropods (i.e. aphids) during winter, was found to be more common in the fertilized stands (Edenius et al., 2011). Our results suggest that in intensively managed forest areas repeated fertilization of young spruce has the potential to enhance the suitability of these stands as winter feeding habitat for coniferous foliage-gleaning insectivorous birds compared to unfertilized stands in the same developmental stage. However, intensification of forest management further impedes habitat quality for more specialized species and generally reduces the diversity of forest birds by simplifying structure and composition of forest stands and shortening the rotation period. Therefore, careful planning of spatial arrangement of treatment units with different management, retention of natural forest and/or structures and legacies such as dead wood and deciduous trees are necessary to promote avian diversity in intensified forest management schemes.

Controlling morphology of peptide‐based soft structures by covalent modifications

Control of gross morphology of soft matter remains an area of continued interest. Towards this goal, this paper describes conjugation of mannose residues and introduction of thiol functionalities to diphenylalanine (FF) dipeptide, a fibrillating motif from amyloid-β peptide, as covalent modifiers of its solution-phase self-assembly process. It was found that covalent attachment of a single mannose residue to FF leads to the retention of tubular structures, whereas the conjugation of two mannose units, linked through a Lys residue, resulted in a dramatic change from tubular morphology to spherical structures. However, a similar switch to spherical objects could be achieved by introducing a thiol residue in the mono-mannosylated FF dipeptide. Interestingly, these glycopeptides also exhibited interaction with concanavalin A, thereby providing an indirect evidence for the availability of mannose units for the process of lectin-carbohydrate interaction in the self-organized state.

Structure retention in cross-linked poly(ethylene glycol) diacrylate hydrogel templated from a hexagonal lyotropic liquid crystal by controlling the surface tension

Retaining hexagonal lyotropic liquid crystal (LLC) structures in polymers after surfactant removal and drying is particularly challenging, as the surface tension existing during the drying processes tends to change the morphology. In this study, cross-linked poly(ethylene glycol) diacrylate (PEGDA) hydrogels were prepared in LLC hexagonal phases formed from a dodecyltrimethylammonium bromide (DTAB)/water system. The retention of the hexagonal LLC structures was examined by controlling the surface tension. Polarized light microscopy, X-ray diffraction and small angle X-ray scattering results indicate that the hexagonal LLC structure was successfully formed before polymerization and well retained after polymerization and after surfactant removal when the surface tension forces remained neutral. Controlling the surface tension during the drying process can retain the nanostructures templated from lyotropic liquid crystals which will result in the formation of materials with desired nanostructures.

Examining structure–activity correlations of some high activity enzyme preparations for low water media

A first study of the comparison of structures of enzymes (by FT-IR and CD) in different high activity (in low water media) preparations is reported. Using chymotrypsin and subtilisin as models, we have studied various factors that distinguish enzyme precipitated and rinsed with propanol (EPRP), crosslinked enzyme aggregates (CLEA), protein coated microcrystals (PCMC) and crosslinked protein coated microcrystals (CLPCMC). The suspensions in organic media were assayed for catalytic activity, and structures were probed by FT-IR and CD measurements. CD studies of enzyme suspensions were possible by using a rotating cell accessory. There was a generally good correlation between higher catalytic activity and retention of native structures. Activity and retention of native structure was always higher if aqueous enzyme solution was added to propanol rather than vice versa in the precipitation step of these preparations. The work identifies factors which may lead to better biocatalyst designs for low water media.

Evidence-Based Transition to Practice: Developing a Model for North Carolina

To enhance patient safety and increase retention of new nurses, structures and processes should be developed to ensure that newly licensed nurses are afforded the opportunity to gain confidence and competence as they enter the workforce. This commentary provides an overview of the work performed to date in North Carolina to build an evidence-based transition-to-practice model.

Hollow pyramidal lattice truss structures

Abstract Pyramidal lattice core sandwich structures with millimeter scale hollow trusses have been assembled from 304 stainless steel tubes and bilayer face sheets, and bonded using a vacuum brazing approach. Rigid, large interfacial area nodes between the trusses and face sheets could be made by this approach. The through-thickness compression and transverse shear stiffness and strengths of these structures have been measured and compared with analytical predictions based upon plastic yielding and the various modes of lattice strut buckling. The compressive and shear strengths of hollow pyramidal lattices with relative densities of 1 to 6 % were 3 to 5 times those of solid pyramidal lattices of equivalent relative density and were accompanied by significant strength retention of the post buckled structures resulting in very high specific energy absorption.