Bulk Samples Research Articles

Evaluation of degradation phenomena in the electric potential distribution inside organic light-emitting diodes by electron holography

Understanding the intrinsic degradation processes of organic light-emitting diodes is necessary to improve their lifetimes. This intrinsic degradation is typically caused by carrier injection at the interface between the hole transport layer (HTL) and the emissive layer (EML). However, revealing the charge behavior in this local region with a high spatial resolution remains challenging. Thus, this study employed electron holography, a transmission electron microscopy (TEM) technique, to measure the nanometer scale potential distribution inside an OLED composed of N,N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4,4′-diamine (α-NPD) and tris-(8-hydroxyquinoline)aluminum (Alq3) that was degraded via continuous voltage application. The α-NPD and Alq3 functioned as the HTL and EML, respectively. The degraded OLED was found to exhibit several potential distributions, depending on the local positions from which the TEM samples were lifted out of the same bulk sample. The distributions included (i) formation of a potential valley at the α-NPD/Alq3 interface, (ii) disappearance of electric fields within the organic layers, and (iii) similar distribution to original before degradation. We suggest that the degradation was caused by charge accumulation, cationization of Alq3, and local failures. Thus, this study revealed the influence of electric degradation at the nanometer scale because of charge injection to the α-NPD/Alq3 interface. Electron holographic degradation analysis near the HTL/EML interface is expected to aid in the development of design guidelines for preventing device degradation and thus extend device lifetime.

Enhanced thermoelectric performance of p-type BiSbTe through incorporation of magnetic CrSb

There is evidence that magnetism can potentially increase the thermopower of materials, most likely due to magnon scattering, suggesting the incorporation of intrinsic magnetic semiconductors in non-magnetic thermoelectric materials. Here, samples of p-type Bi0.5Sb1.5Te3 with 10 at. % excess Te are ball-milled with varying ratios of the antiferromagnetic semiconductor CrSb (0, 0.125, 0.5, and 1 wt. %) to prepare bulk samples by spark plasma sintering technique. The thermopower of samples containing CrSb is increased due to an increase in the effective mass of the charge carriers, indicating that there is a drag effect originating from the magnetic particles. However, this was at the expense of reduced electrical conductivity caused by reduced charge carrier mobility. While overall only marginal improvements in power factors were observed, these samples exhibited significantly lower thermal conductivity compared to the single-phase material. As a result, a peak zT value of ∼1.4 was achieved at 325 K for the sample with 0.125 wt. % CrSb. These results highlight the potential of incorporating magnetic secondary phases to enhance the thermoelectric performance of materials.

Formation of Chemically Complex Intergranular Glass Film: An Effective Strategy to Hinder Grain Coarsening

Thermally driven grain coarsening is a commonly encountered issue in nanocrystalline ceramics, particularly in high‐temperature environments. The intergranular glass film (IGF) constitutes a crucial component of most ceramics and plays a pivotal role in the process of grain coarsening. In this study, it is proposed to impede grain coarsening by constructing a chemically complex IGF comprising multiple dopants with distinct ionic radii. Ternary dopants encompassing Al3+, Y3+, and La3+ ions are simultaneously incorporated into a ZrO2–SiO2 nanocomposite. To fabricate the nanocomposite, an amorphous precursor powder with uniformly dispersed dopants is prepared using a chemical coprecipitation method, followed by rapid hot pressing to obtain a dense bulk sample. The distribution behavior of ternary dopants at IGFs between adjacent ZrO2 nanocrystallites (NCs) is carefully examined. It is revealed that the ternary dopants coexist at the IGFs. Moreover, Si4+ ions exhibit preferential enrichment at the IGFs. Remarkably, the presence of chemically complex IGFs significantly enhances the resistance to grain coarsening in ZrO2 NCs up to 1000 °C. In these findings, valuable insights are offered for designing and fabricating nanocomposites with exceptional resistance against grain coarsening.

R2Pt7MnP4-x (R = Ca, Eu): Intrinsic heterostructures based on a combination of AuCu3- and CaBe2Ge2-type fragments with chemically switchable magnetic interplay

Two quaternary phosphide platinides, Eu2Pt7MnP2.96 (I4/mmm, a = 4.0453(7) Å, c = 26.745(4) Å, V = 437.67(17) Å3, Z = 2, R1 = 0.0262, wR2 = 0.0527) and Ca2Pt7MnP3.02 (I4/mmm, a = 4.0027(5) Å, c = 26.735(5) Å, V = 428.34(14) Å3, Z = 2, R1 = 0.0280, wR2 = 0.0673) were synthesized as single crystals and bulk samples, their crystal structures were established from single-crystal X-ray diffraction data and confirmed by powder diffraction and elemental analysis. The compounds crystallize in the tetragonal system, and represent heterostructures built from the alternating layers of AuCu3- and CaBe2Ge2-type fragments. Both compounds are metallic based on the DFT calculations. Chemical bonding analysis reveals a pattern of covalent and ionic interactions within each compound. Magnetic measurements show both compounds to be ferromagnetic, and reveal an interplay between europium and manganese magnetic lattices, indicative of an exchange bias effect.

Plasticity tuning of thermal conductivity between nanoparticles

We study the effects of uniaxial pressure on the thermal conductivity between two nanoparticles using atomistic simulation. While the system is compressed, we analyze the evolution of contact area, the relative density, and the dislocation density. Lattice thermal conductivity is calculated by non-equilibrium molecular dynamics simulations at several stages of the compression. Despite the increment of dislocation defects, thermal conductivity increases with pressure due to the increase in relative density and contact radius. The behavior of the contact radius is compared with the Johnson–Kendall–Roberts (JKR) model. While there is good agreement at low strain, after significant plasticity, signaled by the emission of dislocations from the contact region, the discrepancy with JKR grows larger with the dislocation density. The results for thermal conductivity show good agreement with previous studies at zero strain, and a theoretical model is used to accurately explain its behavior vs strain-dependent contact radius. Both the Kapitza resistance and thermal resistance decrease with strain but with very different evolution. Simulations of a bulk sample under uniaxial strain were also carried out, allowing for a clear distinction between the role of compressive stress, which increases the conductivity, vs the role of dislocations, which decrease the conductivity. For the NP system, there is the additional role of contact area, which increases with stress and also modifies conductivity. An analytical model with a single free parameter allows for a description of all these effects and matches both our bulk and NP simulation results.

Direct observation of the evolution behavior of micro to nanoscale precipitates in austenitic heat-resistant steel via electron channeling contrast imaging

Precipitation directly determines the high-temperature properties of the austenitic heat-resistant steels. The precipitations of MX, Z-phase, M23C6 and σ-phase, ranging from micrometers to nanometers, are commonly characterized using the scanning electron microscopy (SEM) and transmission electron microscopy (TEM). However, details of their evolution behavior are still unclear due to the limited SEM resolution using the traditional sampling method and the limited spatial resolution of TEM. In this work, field emission SEM-based electron channel contrast imaging (ECCI) techniques with flexible sampling routes were introduced to observe the precipitation evolution behavior of HR3C steel after aging at 700 °C for 8095 h. We showed that the coarse primary-MX and Z-phase in the as-received steel are relatively stable during aging. The coarse M23C6 and tiny secondary Z-phase dispersions were rapidly formed along the grain/twin boundaries and within dislocation arrays inside the grain interior, respectively. We further found that the M23C6 at grain boundaries would change from continuous to semi-continuous due to the formation of σ-phases, while in twin boundaries, it would become continuous over aging. Moreover, we showed that the σ-phases were in-situ transformed from M23C6 at the grain boundaries via its dissolution, facilitating the nucleation of tiny Z-phase inside the σ-phase grains, and this phenomenon has not been reported so far. We have demonstrated that ECCI with an electrolytic-polishing-based sampling route is effective in revealing multi-scale precipitation with high-throughput efficiency, and it allows the direct observation of the complex behavior of precipitates down to the nanoscale using a bulk sample. This method can be used as an efficient way for the quantitative microstructure study.

Correlation between structural modifications and physical parameters of Sb doped InSe alloys for optoelectronic applications

Bulk samples of In0.1Se0.9-xSbx (0 ≤ x ≤ 0.24) were synthesized using the conventional melt-quenching technique. The impact of Sb doping on the structural and physical properties of InSe alloys was systematically explored. The substitution of Sb at the expense of Se introduces defects and dislocations in the lattice, which significantly influence the properties of the InSeSb system. With increasing Sb content, physical parameters such as the average coordination number, cross-linking density, mean bond energy, and cohesive energy were observed to increase. Theoretically calculated band gap values lie between 1.7 and 1.3 eV. X-ray diffraction (XRD) analysis confirmed the polycrystalline nature of the alloys, revealing the coexistence of rhombohedral α-In2Se3 and orthorhombic Sb2Se3 phases. Energy dispersive X-ray spectroscopy (EDX) confirmed the elemental composition, showing the presence of In, Se, and Sb in the bulk samples. Raman and FTIR spectroscopy further validated the presence of distinct structural units and molecular bonds as a function of Sb content, confirming the coexistence of α-In2Se3 and Sb2Se3 phases alongside In–Se, Se–Se, and Sb–Se bonds. A strong correlation was established between the experimental findings and theoretically calculated parameters, including the average coordination number, mean bond energy, glass transition temperature, cohesive energy, and optical band gap. This study provides a comprehensive insight into the compositional dependence of structural and physical properties in InSeSb chalcogenide alloys, enhancing our understanding of their potential applications.

Effect of mechanical milling time on powder characteristic, microstructure, and mechanical properties of AA2024/B4C/GNPs hybrid nanocomposites

In this study, hybrid nanocomposites consisting of an AA2024 matrix reinforced with 1 wt% B4C nanoparticles and 1 wt% GNPs were produced using a powder metallurgy method assisted by mechanical milling. This study aimed to systematically investigate the effect of grinding time on powder characteristics (particle size, microhardness, and morphology) as well as microstructure, densification, and mechanical performance to optimize processing conditions for superior material properties. Microstructural characterization of powders and bulk samples were carried out using a SEM device equipped with EDS. The results indicate that with increasing milling time, the particle size significantly decreased, while the particle hardness increased substantially. Additionally, the sample milled for 8 h achieved the highest relative density among the hybrid nanocomposites, reaching a value of 95.3 %. Mechanical tests revealed that after 8 h of milling, the hardness and tensile strength reached peak values of 164 HB and 314 MPa, corresponding to increases of 56 % in hardness and 43 % in tensile strength compared to the unreinforced alloy. The analysis results confirm that the optimal properties were obtained after 8 h under all conditions.

Chemical structure and hydrocarbon generation potentials of cyanobacteria Schizothrix calcicole and its resistant biopolymer

Microalgae have attracted much attention because of their great potential in the development of sustainable biofuel. In this study, cyanobacteria Schizothrix calcicole was fractionated into different fractions and characterized by elemental analyses, Rock-Eval pyrolysis, and 13C NMR. Closed pyrolysis experiments were carried out on the bulk (BL) sample of S. calcicole and its nonhydrolyzable organic matter (NHOM) fraction. The results suggested the NHOM fraction was composed of a saturated and unbranched or weakly branched hydrocarbon chain with a chain length up to 32, which was highly aliphatic resistant biopolymer similar to algaenan in structure, and exhibited higher oil yield (58.1 %) and oil and gas production potentials (OGPs, 63.9 %) than the BL sample did. Moreover, the n-alkanes for the NHOM fraction showed bimodal distribution and were dominated by long chains higher than C15. On the contrary, the BL sample exhibited unimodal distribution of n-alkanes, in which middle- and short-chain n-alkanes with chain length <17 were more abundant. In addition, the results indicated 13C NMR is an effective approach to evaluate hydrocarbon generation potentials. Our investigation identifies aliphatic biopolymers in cyanobacteria S. calcicole and improves the understanding of hydrocarbon generation of its different fractions.

Evolution of pore structure and cement composition during weathering of conglomerate at Mogao Grottoes in alkaline and arid regions, NW China

Numerous conglomerate grottoes have been excavated and preserved in the arid and alkaline regions of NW China. After millennia of weathering, these conglomerate grottoes have suffered from various weathering issues (such as seepage and collapse) that are internally governed by the distribution of pore networks and the degree of cementation. However, studies on conglomerate weathering have mostly been reported in humid and tropical climates, where intensive chemical weathering occurs. Additionally, characterizations of pore evolution during conglomerate weathering have been restricted due to limitations in detecting pore size and pore type using a single pore characterization method. To fill this gap, this study jointly used mercury intrusion porosimetry (MIP) and computed tomography (CT) to characterize the pore evolution process during conglomerate weathering at Mogao Grottoes, a world heritage site in NW China. Mineralogical, hydrological, mechanical and microscopic characterization were also conducted to understand the changes in compositions of bulk samples and cements during weathering. Results revealed that the majority of pores in conglomerate are concentrated in macropores > 5 μm, followed by mesopores and micropores. During weathering, volume fraction of macropores significantly increases and that of micropores decreases, with median/average pore diameters experiencing an 8- to 10-fold increase. Permeability, porosity and fractal dimension exhibited strong positive linear correlations with median/average pore diameters. Throughout weathering, the abundances of calcite and clay minerals show notable decrease, particularly in cements, resulting in an enrichment of feldspars. Frequently occurring sand-carrying wind activities and salt weathering in arid regions are inferred to be responsible for the major cement loss and porosity generation through physical processes. Our combined MIP-CT method for pore network characterization is also applicable to other lithologies with a wide range of pore sizes. The proposed mechanism of pore evolution and cementation failure provides a scientific base for protecting stone heritages in arid zones.

Precontouring as a Tool to Improve the Laser Powder Bed Fusion Printability of Inconel939 Thin Walls

This work investigates the influence of adding a contour scan prior to hatching (precontouring) on the printability of Inconel 939 thin‐wall sections produced by laser powder bed fusion. Walls with thicknesses ranging from 500 to 1500 μm, manufactured with two hatch scanning parameter sets that give rise to different microstructures and very high density in bulk samples of the same alloy, are investigated. It is shown that, while the texture as well as the grain size and shape is only influenced moderately by the contour scanning strategy, precontouring does lead to a significant reduction of the melt pool depth, an effect that is increasingly pronounced with decreasing wall thickness. This work highlights the role of the precontour scan as a heat sink, shifting the normalized enthalpy input toward lower values and thus limiting the accumulation of excess heat. Precontouring is put forward as a scanning strategy to improve the manufacturability of thin sections.

Hydrothermal niobium (Nb) mineralization and mobilization in the world-class Madeira Sn-Nb-Ta granitic deposit (Amazonas, Brazil)

The Madeira deposit is a world-class tin (Sn) deposit characterized by a unique mineralogical assemblage composed of a massive cryolite (NaAlF3) deposit associated with economically important metals like Nb (0.20 wt% Nb2O5). Although hydrothermal alteration has long been recognized in the cryolite formation, its effects on the mineralization and mobility of Nb remain obscure. This study presents new data on the Nb mineralization of the Pitinga core and border albite-enriched granites provided by nanoscale and site-selective approaches, using transmission electron microscopy and synchrotron-radiation analyses. Pyrochlore is the main Nb ore mineral with three distinct compositional types (U-Pb, Pb-U and Y-bearing varieties). Hydrothermal processes lead to the extensive alteration of pyrochlore into columbite (later designated as columbitization) by a coupled dissolution-reprecipitation mechanism, which evidences the alterability of pyrochlore in a hydrothermal context. Nanoscale analyses of veins and reaction interfaces reveal the presence of additional Nb hosts including fergusonite-(Y), Nb-bearing uraninite and Nb-bearing coffinite which formed from the alteration of pyrochlore. The nature of the altered phases mainly depends on the composition of the parent pyrochlore. Their formation, occurring in absence of direct proximity with remaining pyrochlore, shows that Nb mobilization at macroscopic scale is possible in F-rich reducing fluids. Niobium L3-edge XANES spectroscopy on bulk samples representative of the different facies show that hydrothermal processes change the Nb mineralization by converting primary U-Pb-bearing pyrochlore into columbite and Pb-U/Y-bearing pyrochlores. The columbitization process of pyrochlore led to the increase of the Nb ore grade. Nonetheless, hydrothermal alteration modified Nb mineral liberation, thereby limiting the recovery of the full range of Nb host phases.

The impact of proton ion irradiation on Se70Te20In10 thin films: Linear and non-linear optical properties for photonic applications

The examination of the linear and non-linear optical features was conducted on amorphous ternary Se70Te20 In10 thin films, which were exposed to proton irradiation energy of 3 MeV at varying fluences of 5×1013, 5×1014, 5×1015 and 5×1016 ions/cm2. The bulk sample was produced using the melt quenching method, and subsequently, thin films were obtained through electron beam evaporation. Calculations of linear and non-linear optical parameters were carried out based on transmittance and reflectance data acquired from UV–Vis–NIR spectroscopy spanning 300–2500 nm. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) confirmed an amorphous phase in the films. The optical parameters showed strong dependency on the proton radiation fluence. In addition, the existence of minima or maxima for a number of parameters at a fluence of 5×1014 ions/cm2 showed that this was the optimum fluence. The linear and non-linear properties showed that the sample have potential applications in photonic devices.

Developmental-status-aware transcriptional decomposition establishes a cell state panorama of human cancers

BackgroundCancer cells evolve under unique functional adaptations that unlock transcriptional programs embedded in adult stem and progenitor-like cells for progression, metastasis, and therapeutic resistance. However, it remains challenging to quantify the stemness-aware cell state of a tumor based on its gene expression profile.MethodsWe develop a developmental-status-aware transcriptional decomposition strategy using single-cell RNA-sequencing-derived tissue-specific fetal and adult cell signatures as anchors. We apply our method to various biological contexts, including developing human organs, adult human tissues, experimentally induced differentiation cultures, and bulk human tumors, to benchmark its performance and to reveal novel biology of entangled developmental signaling in oncogenic processes.ResultsOur strategy successfully captures complex dynamics in developmental tissue bulks, reveals remarkable cellular heterogeneity in adult tissues, and resolves the ambiguity of cell identities in in vitro transformations. Applying it to large patient cohorts of bulk RNA-seq, we identify clinically relevant cell-of-origin patterns and observe that decomposed fetal cell signals significantly increase in tumors versus normal tissues and metastases versus primary tumors. Across cancer types, the inferred fetal-state strength outperforms published stemness indices in predicting patient survival and confers substantially improved predictive power for therapeutic responses.ConclusionsOur study not only provides a general approach to quantifying developmental-status-aware cell states of bulk samples but also constructs an information-rich, biologically interpretable, cell-state panorama of human cancers, enabling diverse translational applications.

Occurrence, non-carcinogenic and carcinogenic risk assessment of trace elements in rainwater in the vicinity of a cement factory in northeastern Nigeria

Rapid industrialization and urbanization result in atmospheric pollution with trace elements precipitated and deposited by rain, affecting human health. This study determined the concentrations and non-carcinogenic and carcinogenic risks associated with trace elements in rainwater in the vicinity of the Ashaka cement factory. Samples were collected using a bulk sampler fitted with a high-density polythene funnel. A total of 140 samples were collected in 2020 and analyzed for 15 trace elements using ICP-OES. Multivariate analysis was used to identify the sources of the rainwater trace elements. The results show that the abundance of trace elements in the collected samples was in the following order: Fe > Sb > Cu > Ba > V > Sc > Sr > Mn > Zn > Ti > Hg > Al > Mo > Co. Crustal enrichment factors (EFc) indicated that the samples were extremely enriched with Hg, Sb, Cu, and Mo, moderately enriched with Zn, Ba, V, Co, Sr, Cr, and Sc, and unenriched with Fe, Mn, Ti, and Al. Chronic daily intake (CDI) for both the ingestion and dermal pathways was in the order Fe > Cu > Ba > Cr > V > Mn > Zn > Hg > Mo. The hazard index (HI) was > 1 through the ingestion pathway, indicating a likely non-carcinogenic advertising effect. Similarly, the carcinogenic risk (CR) exceeded the (1.0 × 10–4—1.0 × 10–4) acceptable limit for children and adults, indicating the likely development of cancer among consumers. This revealed that the elements present in rainwater are anthropogenic and are brought about by cement production.

Development and validation of a gene expression-based Breast Cancer Purity Score

The prevalence of malignant cells in clinical specimens, or tumour purity, is affected by both intrinsic biological factors and extrinsic sampling bias. Molecular characterization of large clinical cohorts is typically performed on bulk samples; data analysis and interpretation can be biased by tumour purity variability. Transcription-based strategies to estimate tumour purity have been proposed, but no breast cancer specific method is available yet. We interrogated over 6000 expression profiles from 10 breast cancer datasets to develop and validate a 9-gene Breast Cancer Purity Score (BCPS). BCPS outperformed existing methods for estimating tumour content. Adjusting transcriptomic profiles using the BCPS reduces sampling bias and aids data interpretation. BCPS-estimated tumour purity improved prognostication in luminal breast cancer, correlated with pathologic complete response in on-treatment biopsies from triple-negative breast cancer patients undergoing neoadjuvant treatment and effectively stratified the risk of relapse in HER2+ residual disease post-neoadjuvant treatment.

In situ synthesis, mechanical properties, and reaction mechanism of the WB2–SiC composites

AbstractIn the present work, WB2–SiC composite powders containing 20 vol.% of SiC were in situ synthesized by the boro/carbothermal reduction with WO3, SiO2, B4C, and carbon black as raw materials at 1400°C, 1500°C, and 1600°C, respectively. The as‐synthesized composite powders were then consolidated by spark plasma sintering (SPS) technique to obtain WB2–SiC composite bulk samples. The experimental results showed that the relative density of the WB2–SiC composite ceramic samples achieved in this study was higher than 97.5%. Also, electronic microscopy observations showed that SiO2 had reacted completely during the preparation process, and the SiC grains were homogenously embedded among the WB2 grains with the formation of a three‐dimensional structure. The Vickers hardness and fracture toughness values of the composite ceramic fabricated by powder heat treated at 1400°C were 24.6 ± 0.7 GPa and 5.4 ± 0.7 MPa·m1/2, respectively, which were the highest among three samples prepared in this study.

Atomistic insights into cold welding process of high-entropy alloy nanowires

This research applied molecular dynamics (MD) simulations to investigate the influences of contact pressure, temperature, crystal orientation, and chemical composition on the characteristics of the cold welding joints of CoNiCrFeMn high-entropy alloy (HEA) nanowires. The findings indicate that defect-free cold welded joints can be successfully formed within a contact pressure range of 10 to 10,000 Pa. In addition, changing the contact orientation could cause a significant change in the structure transformation level. The dislocation distribution is continuous when the top and lower blocks are oriented in the same direction. Dislocation lines, on the other hand, stop at the interfacial area and have a discontinuous shape when the weld joints are formed from different orientations. Furthermore, creating from the same orientations leads to a higher ultimate tensile strength (UTS) value than the different orientation cases. In the temperature range of 150 K–350 K, the deformation behaviors of the cold weld joint are stable. Besides, there was no noticeable change in the weld joint when the composition changed. Because of the strong crystal structure of the cold welding joints, the UTS values of the cold-welded joints range from 13.2 to 17.4 GPa, comparable to the bulk samples.

Ba and Sr isotopic patterns from step‐leaching experiments on the pristine Aguas Zarcas CM2 meteorite

AbstractStepwise acid leaching experiments were performed on the pre‐rain CM2 fall Aguas Zarcas to interrogate release patterns and isolate fractions with isotopic anomalies. Acid leachates and a bulk sample were analyzed for elemental abundances via solution ICP‐MS, and Sr and Ba isotopic compositions were measured using TIMS. Isotopic systematics reveal diverse values for the bulk sample and leachates, interpreted to reflect the Aguas Zarcas parent body history. Compared with the NBS987 standard, μ84Sr values for the bulk sample average + 90, while the leach fractions yield +326 to −2089, with the largest μ84Sr depletions in the strongest acid leachates. For Ba isotopes, the bulk sample shows resolvable depletions (μ values) in 130Ba (−210), 135Ba (−64), 137Ba (−73) and 138Ba (−89). Early leachates show positive anomalies in 130Ba (up to +2295), 132Ba, 135Ba, 137Ba, and 138Ba. In contrast, final leachates show strong depletions for the same nuclides (up to −60,000 ppm μ130Ba). The Sr and Ba isotopic anomalies found in the earlier leachates suggest that nucleosynthetic signatures were redistributed to more soluble phases during parent body alteration. Moreover, contrasting p‐nuclide Sr and Ba nucleosynthetic anomalies suggest that presolar contributions came from a variety of nucleosynthetic sources, including possibly a rotating massive star undergoing a core‐collapse supernova or an electron capture supernova.

Wheat grain classification using hyperspectral imaging: Concatenating Vis-NIR and SWIR Data for single and bulk grains

Wheat variety identification is an essential component of the official inspection of wheat grains to determine their quality and trade value. Traditionally, wheat class identification requires deep knowledge about the appearance of plants and kernels, their history and distribution. Therefore, there is an urgent need for an automatic technology to standardize the nomenclature of wheat varieties to enable both growers and producers to identify their grains practically. The present study investigated the feasibility of Visible-Near Infrared (Vis-NIR) and Short-Wave Infrared (SWIR) spectral imaging to identify wheat classes. Both sides of the wheat kernel as single kernel measurements and bulk grains were used to acquire hyperspectral data and vertical and horizontal data concatenation was implemented to explore performance differences. In addition, the classification of bulk kernels from single kernel data was investigated. Spectral data was pre-treated by standard normal variate (SNV), Savitzky-Golay first (SG-1) and second derivatives (SG-2) and linear discriminant analysis (LDA), support vector machine (SVM) and artificial neural network (ANN) were applied as the classification algorithms. Furthermore, feature selection was utilised using the minimum redundancy maximum relevance (mRMR) algorithm to investigate the performance difference between data concatenation and feature selection. The results showed that ventral (up) side data showed better classification performances than reverse (down) side data, while Vis-NIR data achieved higher classification accuracies than SWIR data. However, the best classification performance for single kernels was obtained by LDA-SNV using up and down data in the Vis-NIR and SWIR regions vertically and horizontally concatenated with an accuracy of 93.72% for 10-fold cross-validation and 94.93% for test sets. Models based on a hundred features did not achieve the accuracy of models based on concatenated data. Moreover, classification performances of bulk samples were higher than single kernels, which achieved 100% accuracy for both cross-validation and test sets. The study demonstrates that spectral imaging has a high potential to identify wheat classes non-destructively.