Material Specimens Research Articles

A new species of Passiflora (Passifloraceae, subgenus Passiflora) in the flora of Colombia discovered in uncharted Andean territory

A new species of Passiflora belonging to the subgenus Passiflora (supersection Stipulata, section Kermesinae) is described and illustrated from living material and herbarium specimens. Passiflora pitalensis is similar to P. lehmannii, and it can be recognized primarily by its petiole green, leaves with broader lobes, peduncle green, bract lanceolate, corona filaments in 5 series with outer filaments in 2 series, fruit ovoid, and seed margin dentate. This species is rare and endemic to Colombia in the Andean region at elevations ranging from 1,749–2,027 m and should be considered Endangered (EN) due to its restricted occurrence with a small population size of no more than 90 individuals.

Synthesis of Hybrid Composites from Bio-Based Fillers: Chicken Feather, Groundnut Shell, Sawdust

Experimental research has investigated the mechanical characteristics and water absorption performance of polyethylene-based composites reinforced with sawdust, chicken feathers and groundnut shells. Composite samples have been produced with preset volumetric ratios (20%, 30%, 40%, and 50%) at 160°C and 25 kN pressure. A compression molding machine was used to produce specimens of composite materials. The findings indicate that the composites exhibit promising mechanical properties, making them potentially suitable for various applications. However, the waste polyethylene sheet was tested for comparison. It displayed a tensile strength of 7.56 MPa, impact strength with an average energy absorption of 0.093 J, and hardness strength with an average energy value of 92.72 J. The water absorbency data showed minimal water absorption for composite samples, indicating their resistance to water penetration. Similarly, the thickness swelling data revealed no significant change in thickness after immersion, demonstrating dimensional stability in the presence of moisture. This article presents the details of these experiments conducted systematically.

Unravelling the mishmash: A new phylogeny for the family Empheriidae (Psocodea, Trogiomorpha) with a new genus and species from Cretaceous Charentese amber

The order Psocodea, including barklice, booklice, and parasitic lice, is diverse and widely distributed since the Cretaceous. That is particularly the case for the speciose extinct family Empheriidae (Psocodea, Trogiomorpha, Atropetae), recently fused with the ‘Archaeatropidae’. Understanding the evolution of barklice is dependent in part on studying this family, as its representatives have been found from the Early Cretaceous to the Eocene, surviving the K/Pg extinction event. The phylogenetic relationships of Empheriidae in relation to other families, such as Lepidopsocidae or Psoquillidae, have been extensively debated. However, distinguishing diagnostic characters for the Empheriidae has proven challenging. In this study, we describe the new empheriid Santonipsocus mimeticusgen. et sp. nov. from Cretaceous Charentese amber (France). It is the third empheriid species found in this locality. The new genus is compared with the other genera in the family, and Proprionoglaris guyoti and Proprionoglaris axioperierga are revised based on the type material and new specimens. We explore the phylogeny of Empheriidae, both the relationships with other families and the inner relationships between the genera, through maximum parsimony analysis and Bayesian inference analysis. Our results suggest that Empheriidae may represent a paraphyletic evolutionary grade to the rest of Atropetae. The phylogenetic relationships between genera align with the biogeography of the family and support previous hypotheses. In addition, we discuss the possible biology of the members of the family, shedding light on the evolutionary history of Empheriidae.

How Does Ethylenediaminetetraacetic Acid Irrigation Affect Biodentine? A Multimethod Ex Vivo Study.

The activity of biomaterials used during endodontic treatment can be affected by various factors. One of them is the chemical action of the irrigant that they are exposed to. The aim of this multimethod ex vivo study was to evaluate the influence of ethylenediaminetetraacetic acid (EDTA) on the surface appearance and chemical composition of Biodentine used in perforation repair. Twenty material specimens were prepared according to manufacturers' recommendations and divided into two setting-time-based groups, tested after 45 min (group A) and 24 h (group B) of setting. Material was irrigated with 17% EDTA solution with or without simultaneous ultrasonic activation. The surface characteristics and the chemical composition analysis of the Biodentine specimens were performed with the aid of a scanning electron microscope (SEM) and an energy dispersive spectroscopy (EDS) method, respectively. The volumetric loss of material was measured by dedicated digital software in an optical microscope. Statistical analysis was performed. The EDS study confirmed that after the rinsing protocol, the percentage content of elements differed between the groups. The EDTA rinse, whether ultrasonically activated or not, visibly affected the surface appearance and chemical composition of Biodentine. The specimens' surface subjected to irrigation was more irregular under SEM than in a control group. The US activation of the liquid amplified its impact on the tested material. The average volume loss in group A after 5 min irrigation was 3.98 µm3 for each µm2 of the chosen area and it increased up to 7.74 µm3/μm2 after the ultrasonic activation. In group B, indicated volume loss values were 6.30 and 11.70 µm3/μm2 for 5 min irrigation without and with US activation, respectively. Using a 20 min irrigation time and ultrasonic activation increased it up to 32.71 µm3/µm2. Each rinsing protocol involving irrigation with ethylenediaminetetraacetic acid modified the surface features and the chemical composition of the evaluated hydraulic tricalcium silicate cement. Further research is needed to indicate the possible impact of the observed changes on its long-term clinical performance.

Combing through museum collections. A “museomic” application of ZooMS

AbstractThis article presents the application of Zooarchaeology by Mass Spectrometry (ZooMS) to osseous Longobard artifacts from the collection of the “Musei Reali di Torino” (MRT; Torino, Italy). Like most archaeological items made of worked bone/antler in museum collections, the raw material of such specimens is usually attributed to deer, often without accurate taxonomic attribution. Therefore, the main aim of the present investigation was to shed light on taxonomical aspects using biomolecular approaches.We first examined the collagen preservation of the artifacts, then we compared three sampling methods (invasive, eraser‐based, and bag‐based), and we evaluated the quality of the collagen fingerprint obtained. Overall, we found a good, albeit not optimal, biomolecular preservation status, even in heavily restored objects coming from the 19th‐century collections.Out of 37 specimens analyzed through matrix‐assisted laser desorption ionization–time of flight–mass spectrometry (MALDI‐TOF‐MS) and nanoHPLC‐tandem MS, 31 yielded usable data. The results confirmed the widespread use of cervid as the osseous raw material for comb‐making in Longobard times in Piedmont, but we also found that bovine bones (Bos but also other taxa belonging to family Bovidae, such as caprines) and equid bones were exploited—demonstrating opportunistic use of animal resources. As far as the method is concerned, the ZooMS peptide markers useful to distinguish between bovids and cervids (m/z 1580 vsm/z 1550) (Buckley et al., 2009) are more frequently detected when analyzing bone chips, that is, with the invasive sampling method, rather than collagen extracts obtained using non‐invasive techniques. Nonetheless, the eraser method (eZooMS) seems to be a good trade‐off between invasivity and quality of the information obtained: eZooMS sampling does not leave visible marks on the object and therefore can contribute to facilitating the routine application of biomolecular methods in the daily practice of museum conservation laboratories. Indeed, an important outcome of the present study has been the establishment of a close collaboration between museum and biomolecular specialists.Taken together, our results suggest that the Longobards had a preference towards locally available resources, although this work did not highlight a clear association between raw material (deer, cattle, and other bovids) and object typology (in the case of combs) or function, except for buttons. The overall information obtained by this study confirms the potential of biomolecular approaches for reconstructing the biography of museum objects with a long and complex life and demonstrates the value of zooarchaeological study of museum collections.

The Effect of Notch Depth on the Absorbed Energy of High-Toughness Steels in the DWTT

Abstract Because of the larger specimen dimensions and more significant ligament for crack growth, the drop-weight tear test (DWTT) has become more widely used than other impact tests. On the other hand, very little information is available from DWTT experiments on weld metal (WM). In the present study, in addition to the standard chevron notch (CN) DWTT specimen with a notch depth (ND) of 5.1 mm, API X65 specimens with 10- and 15-mm ND were tested on the WM and also the base metal (BM). Fracture energies versus the ND were plotted, based on which tests can be performed successfully with lower-capacity DWTT machines to predict the absorbed energy for each ND, by specimens with increased ND and reduced absorbed energy. The standard requires thickness reduction for specimens thicker than 19 mm. With the method proposed in the present study, high-grade specimens can be tested with their original thickness. In the DWTT, regardless of specimen materials (BM or WM), about 44 % of the absorbed energy is spent on crack initiation, and 56 % is spent on crack growth. In all specimens, the BM absorbed energy was more than that of the WM. Therefore, this study proposes that the API standard, which does not include DWTT on the WM, should require performing DWTT on WM specimens. Hence, the results of the current study can form the basis for further studies that can initiate the development of new standards on the WM.

Objective Function Distortion Reduction in Identification Technique of Composite Material Elastic Properties

In studies of structural mechanics, modal analysis, presented in this paper, is an important tool for analyzing the vibration of an object and its frequencies. In modal analysis, different modes of vibration and the frequencies that generate them are considered. The study covers the nondestructive identification of the elastic characteristics of materials, which involves stochastic algorithms and the application of reverse engineering (i.e., the comparison of reference eigenfrequencies with the results of mathematical models). Identification is achieved by minimizing the objective function—the smaller the value of the objective function, the higher the identification accuracy obtained. By changing the parameters of a material’s mathematical model during identification, certain (usually higher order) modes can change places in a natural frequency spectrum. This leads to the comparison of different order eigenfrequencies, slow convergence and poor accuracy of the identification process. The technique involved in this work is the mode-shape recognition of a specimen of material with an “incorrect” set of elastic properties. The results prove that the identification accuracy of a material’s elastic properties can be increased if an “incorrect” set of elastic properties is removed from the identification process. The research covers only numerical research, with a physical experiment simulation.

Modelling of crack propagation in miniaturized and normal SENB specimens based on local failure criterion

The use of miniaturized specimen testing methods is a promising way to solve the problem of limited materials in RPV monitoring programs. The use of miniature specimens allows the evaluation of fracture toughness from other specimen materials used. In particular, the small-size compact tensile test specimen (0.16T CT) is promising for the determination of fracture toughness, as it can be produced from the standard size Charpy specimen that has already been tested. However, if we have only 0.16T CT test, we cannot investigate the dimensional response and also have only one restricted deformation state, which may pose problems in verifying geometry independence and determining local parameters for state-of-the-art analyses. It is therefore recommended to prepare at least two tests with two different restricted deformation specimens. Therefore, the testing of mini single edge notched bending (SENB) is also required and can be worked out from the Charpy specimens. The paper presents the determination of fracture toughness for these miniaturized specimens by modifying the virtual crack closure technique (VCCT) simulation method using GTN parameters instead of energy release as the driving force. This allows the calculation of the J-integral to proceed in parallel with the crack propagation.

Empirical models for the error induced in piezoelectric ceramic transducer-based acoustic ranging instrumentation and measurement

This article presents experimental methods and analytics for developing statistical models for ultrasonic sensors to improve reliability, repeatability, and signal-to-noise ratio (SNR) in static environments. The experiments use commercial piezoelectric ceramic transducers and over 4100 calibrated readings for three specimens of different materials. Using commercial piezoelectric ceramic transducers, the spatial-temporal approach considers range, environmental factors, material characteristics, and their interactions. A true value approach is used to formulate the error as a function of the distance measured in the time-of-flight (ToF) method at zero azimuth angular directivity. The three statistical models, linear temperature, averaged linear regression, and averaged cubic regression models, are formulated and validated. The most influential parameters in the calibrating distance with an acoustic sensor are the range, coupled effect of temperature, and material characteristics, followed by temperature. The linear model increases the SNR within 0–40 cm from ±20 dB to ≈80 dB, and the cubic model increases the repeatability of the measurement by reducing the absolute error for the entire range of sensors from ±3 cm to less than −1 cm.

Modification of nominal strength scaling laws to pseudo-ductility

We investigate the influence pseudo-ductility has on the notched strength and size-effect behaviour of typical notched specimens of quasi-isotropic pseudo-ductile composite materials. Our previous findings reveal that pseudo-ductility enhances translaminar toughness and nominal strength recovery but can negatively affect specimens below a critical notch size. The traditional Bažant Size Effect Law (SEL) does not adequately capture these observations, necessitating modifications to account for the non-recoverable pseudo-ductile damage past the pseudo-yield strength. We propose modifications to the nominal strength scaling laws, aiming to characterise both the notched strengths for a given notch radius and the size effect due to pseudo-ductility. Modifications are applied to centre-cracked (CC), elliptical hole (EH), and open-hole (OH) specimens for a wide range of pseudo-ductile materials. The proposed modifications for nominal strength predictions agree with FE estimates across all three notch shapes (CC, EH, and OH). The findings suggest that the presented SEL serves as a valuable tool for understanding and assessing the size-effect behaviour of pseudo-ductile composites.

Thermal reaction of firebrand accumulation in construction materials

This paper presents research concerning the thermal firebrand reaction due to its accumulation in specimens of current construction materials commonly applied to the exterior of dwellings in southern Europe. An extensive fire experimental campaign is undertaken, in which firebrands are deposited on the plane surfaces of the material specimens and the temperature is measured on the top and bottom construction specimen surfaces. The materials chosen for this work are currently applied to either the roof, exterior walls and windows, and were recommended as either fire resistance or good behaviour for high temperatures. It will be possible to verify their firebrand reaction, more precisely, the type of ignition, the smoke, droplet production, and even their insulation capabilities. It is also tested for the efficiency of a metal mesh to prevent the entrance of firebrands into the air vents of façades and chimneys in dwellings. A thermal numerical model is also used to study the efficiency of the insulation properties of some construction materials for firebrand deposition by measuring the level of heat flux circulation during the full time analysis.

Effect of surface roughness and polishing orientation on fatigue life and fracture fatigue entropy

AbstractThe effect of surface roughness and polishing orientation on fatigue life is investigated. Fully reversed bending fatigue tests are conducted on ASTM A1008 specimens having surface roughness asperities ranging from mirror finish (Ra = 0.05 μm) to coarse (Ra = 1.5 μm). Two polishing directions (i.e., orientations) are examined. For the range of roughness values tested, the results suggest that polishing orientation has a strong influence on fatigue life. Specifically, within the range of surface roughness values tested, fatigue life was found to be relatively insensitive to surface roughness asperities when the roughness orientation was parallel to the direction of surface stress but sensitive to surface roughness asperities when the orientation crossed the direction of surface stress. Results are generalized using the concept of fracture fatigue entropy (FFE). It is shown that, unlike fatigue life, FFE is independent of polishing orientation, a noteworthy result. To explain the behavior of FFE in relation to surface roughness asperities, a fatigue thermodynamics theory is presented that hypothesizes that all specimens of the same material fail at equivalent entropy levels.

The Effect of Exposure to Candida Albicans Suspension on the Properties of Silicone Dental Soft Lining Material.

While functioning in the oral cavity, denture soft linings (SL) are exposed to contact with the microbiota. Dentures can offer perfect conditions for the multiplication of pathogenic yeast-like fungi, resulting in rapid colonisation of the surface of the materials used. In vitro experiments have also shown that yeast may penetrate SL. This may lead to changes in their initially beneficial functional properties. The aim of this work was to investigate the effect of three months of exposure to a Candida albicans suspension on the mechanical properties of SL material and its bond strength to the denture base polymer, and to additionally verify previous reports of penetration using a different methodology. Specimens of the SL material used were incubated for 30, 60 and 90 days in a suspension of Candida albicans strain (ATCC 10231). Their shore A hardness, tensile strength, and bond strength to acrylic resin were tested. The colonization of the surface and penetration on fractured specimens were analysed with scanning electron and inverted fluorescence microscopes. Exposure to yeast did not affect the mechanical properties. The surfaces of the samples were colonised, especially in crystallized structures of the medium; however, the penetration of hyphae and blastospores into the material was not observed.

Acoustic emission characteristic of sandstone and sandstone like material under multi-path loading.

Using spline interpolation to select proportions of similar materials, a comparative analysis of the fracturing behavior of sandstone specimens and similar material specimens was conducted through Brazilian splitting tests under multi-path loading. The study revealed that during stepwise loading, both sandstone and similar materials exhibited memory effects and plastic deformation. However, under constant velocity loading, the relationship between force and displacement in sandstone showed linearity after compaction. Employing MATLAB optimization algorithms for the inversion of acoustic emission event information, the distribution of fracture points, and the evolution of cracks were analyzed. The findings indicated that under stepwise loading, both sandstone and similar materials exhibited banded distribution of peak frequencies, with sandstone concentrated in the mid-low-frequency range and similar materials leaning towards the low-frequency range. The amplitude-frequency characteristics of acoustic emission signals suggested that initially, sandstone produced low-frequency, low-amplitude signals. As cracks developed, these signals gradually transformed into high-frequency, high-amplitude signals, ultimately leading to macroscopic failure. The ringing counts and b-values of sandstone displayed an approximate "W" shape distribution, with a subsequent decrease in b-values during final failure. In contrast, the acoustic emission counts were inversely related to b-values. Similar materials exhibited slightly more acoustic emission counts than sandstone, with relatively lower b-values. The crack development process of both sandstone and similar materials was confirmed through these observations. From the perspective of section initiation and local damage, sandstone and similar materials exhibited similar failure characteristics. The proportions of quartz sand: cement: water = 9:1:0.9 in similar materials demonstrated the most similar characteristics to sandstone in terms of mechanical loading, acoustic emission features, and failure morphology. This suggests that these similar materials can be used as substitutes for sandstone in analogous simulation experiments. The study provides theoretical support for understanding rock fracture mechanisms, offers guidance for the selection and proportioning of similar materials, and holds significance for predicting and controlling rock fracture behavior in engineering applications.

Updates of the removable biological shielding blocks inside of the test cell, part of the test systems of IFMIF-DONES

The International Fusion Materials Irradiation Facility - DEMO Oriented Neutron Source (IFMIF-DONES) is a facility which is designed under the framework of the EU fusion roadmap. It is going to be an essential irradiation facility for testing and qualifying candidate materials under severe irradiation conditions of a neutron field having an neutron irradiation effect on materials like the one expected in a commercial fusion power reactor. The material specimens are irradiated in a containment structure named Test Cell (TC), which is part of the Test Systems (TS).The first protecting „barrier” against irradiation affecting the surrounding of the TC, are the Removable Biological Shielding Blocks (RBSBs). These ∼9 m height, ∼80 tons elements, which are formed by stainless steel liners filled with heavy concrete, need to be remotely handled as after the first experiments they will get dose rates above the hands-on limit. Irradiation will also result in a large nuclear heat power deposited in the shielding blocks, therefore needs to be actively water cooled by a system of embedded pipes to control the temperature.In this paper the updated design of the RBSBs is described, including the latest achievements and proposals for feasible manufacturing, lifting and positioning possibilities of the blocks inside of the TC respecting the given tolerances.

Hot Embossing of Micro Grating and Its Replication Accuracy

The Hot Embossing (HE) process was applied in the fabrication of micro grating. High-density polyethene (HDPE) was used as a specimen material for producing microstructure components and parts. In this research, a series of experiments were conducted using an HDPE specimen and embossed the polymer under different parameters such as temperature, embossing time, and embossing force as factors. The experimental setup was based on a response surface method (RSM) that employed a face composite design. The constructed RSM quadratic models assisted in analysing the response parameters, namely accuracy and surface roughness, to determine the relevant linkages between the input variables and the replies. The results defined that hot embossing temperature and hot embossing force will enhance the accuracy and surface quality of the micro grating. Based on RSM, the results revealed that the optimal parameters were as follows: hot embossing temperature is 1650c, embossing force is 10kN/s, and embossing holding time is 150 seconds. Under this condition, the actual deviation of accuracy and surface roughness is 5,75% and -1.32% respectively compared to the actual size of the micro grating mould. Hence, it is highly agreed with the model prediction value. In conclusion, optimization of process parameters on the hot embossing system that was developed is promising to fabricate the HDPE micro grating substrate with optimum dimensional accuracy and surface quality.

Mechanical properties and risk characterization of surrounding rocks containing various blocks of arch-shaped holes under biaxial compression

In most rock engineering, the rock mass was cut into different blocks by natural structural planes, and the stability of underground openings was affected by the type, number, position and mechanical properties of rock blocks. In this study, the biaxial compression tests were conducted using rock-like material specimens with prefabricated arch-shaped holes and different types of blocks, and the failure and crack propagation properties of surrounding rocks were studied. Firstly, the location and danger degree of blocks in rock mass were classified, and the rock block danger analysis (BDA) method was proposed. Secondly, the support effect on the stability of surrounding rocks with different blocks was studied. Then, the deformation, strength, crack area ratio, and debris distribution characteristics of specimens were analyzed. Finally, the reasonable support schemes were proposed for surrounding rocks with different types and sizes of blocks. The test results showed that the σ-ε curve of holed rocks was similar to that of intact rocks, and the micro-cracks evolved into macro-cracks at crack destabilization expansion stage, followed by large deformation of whole specimens and spalling. Under support condition, as the block size increased, the crack area ratio decreased and the stability of holed specimens improved. Furthermore, the biaxial compressive strength of the surrounding rock and the stability of the holed specimens decreased as the block danger coefficients increased.

Two new species of Hechtia (Bromeliaceae; Hechtioideae) from Jalisco, Mexico

Backgrounds and aims – The genus Hechtia (sensu lato) is distributed from the southern United States to northern Central America and includes 95 species. Recent botanical explorations, carried out in the Colima and Jalisco states in search of H. reticulata, led to the discovery of two new species. The aims of this work were to complete the morphological description of H. reticulata and describe these two new species. Material and methods – This study was based on fieldwork and on the revision of literature, protologues, type material, and herbarium specimens. The specimens collected were prepared for storage in the herbarium, analysed, measured, and descriptions were made; measurements were taken from dried specimens. Due to their morphological similarities and the closeness of their populations, the proposed species are compared with H. reticulata. Key results – We propose two new species of Hechtia for Mexico (H. costalegrensis and H. pacifica); an epitype and a complete description of H. reticulata are also provided. The diagnostic characters and morphological affinities of the new species are discussed, including complete morphological descriptions and images; a comparative table is presented, showing the morphological differences between the new species and H. reticulata. A distribution map of the taxa described here and of H. reticulata is included, as well as an identification key and a list of examined specimens of all Hechtia species known to date from Colima and Jalisco.

Unified theoretical solutions for describing the crack-tip stress fields of mode-II cracked specimens under the fully plastic condition

Potential novel singular solutions to the crack-tip stress fields beyond the asymptotic solution frame are discussed in this study. It is believed that one of them is not only suitable for the crack-tip stress fields of mode-I cracked specimens but also for those of mode-II cracked specimens. The crack-tip stress fields of mode-II cracked specimens are investigated based on the singular solution and the stress factor of mode-II cracked specimen derived from energy density equivalence principle. Further, special functions for describing the coefficients of normalized stress distributions of mode-II cracked specimens are proposed. The method to determine the parameters in the theoretical solutions are introduced. To give an example, one set of parameters for compact shear specimen under plane-strain conditions are determined by the finite element analysis of a few typical materials and geometries conditions. Finally, comparisons of radial and circumferential stress distributions and contour lines of equivalent stress are completed for the compact shear specimens and Arcan-shaped shear specimens of power-law plastic materials under plane-strain and plane-stress conditions. And the results show that the applicability and reliability of the proposed unified theoretical solutions are verified.

Hardness Test Analysis on ST 37 Steel Plate Material and Aluminum Using the Brinell Test Method

One of the most frequently used methods of material testing is hardness testing. The aim of conducting research on material hardness is to determine the hardness value of the material specimens tested, namely ST 37 steel plate and aluminum plate. The test method is to use the Brinell hardness test where the values ​​obtained during testing are from the force load, indenter diameter and pressure trace diameter and the pressure time that has been determined. By using testing tools such as hardness tester, mechanical caliper, indenter, flat file, stopwatch. And the materials used are ST 37 steel plate, aluminum plate and sandpaper. From the test results obtained we can calculate the Brinell hardness value of the test material. The value from the calculation of test data where the highest hardness value using the Brinell method (BHN) for ST 37 steel plate material is 256.992. Meanwhile, the highest hardness value using the Brinell method (BHN) for aluminum plate material is 55,182.