We propose a novel geometric characterization method for flat-faceted crystals bounded by a single simple crystallographic form - the rhombic dodecahedron. The approach utilizes distances between six pairs of parallel facets and the lengths of three false edges (out of six possible) resulting from anisotropic crystal growth. Our study has established the existence of exactly 34 combinatorially distinct, full-faceted real rhombic dodecahedra. For each type, we determined the range of crystal shape variations using the semi-axial lengths of the minimal-volume circumscribed ellipsoid. The results demonstrate that all real rhombic dodecahedra, except for eight special forms, can exhibit the complete spectrum of possible shape variations. These eight exceptional forms cannot develop tabular morphologies with bidirectional isometry. The obtained results provide valuable tools for precise analysis of rhombic dodecahedral crystal morphology and for establishing morphogenetic correlations between the degree of crystal distortions and the dissymmetry of the crystal-forming environment. This information is relevant for assessing the typomorphic features of natural diamonds, garnets, sodalites and magnetite crystals, as well as their synthetic analogs and other chemical compounds.

Effects of synthetic diamond abrasives on the surface quality of CAD-CAM restorative materials.

Material removal mechanism in femtosecond laser-microstructured natural single-crystal diamond cutting tools by finite element simulation and experimentation

This study investigates the effectiveness of three polishing systems on the surface roughness and gloss of different CAD/CAM reinforced resin composites, one of which is an experimental short fiber-reinforced composite (SFRC CAD). A secondary objective was to evaluate whether specific material-polishing system combinations could achieve clinically acceptable thresholds for surface roughness and gloss. Ninety plate-shaped specimens were prepared from three CAD/CAM reinforced resin composite blocks: experimental SFRC CAD, TRINIA (TR), and Lava Ultimate (LU). Surface roughness and gloss measurements for all specimens were determined at baseline. Then, material specimens were divided into three study groups (n = 10): Sof-Lex diamond polishing system (SOF), OptraGloss polishing system (OPT), and silicon carbide papers (1200-4000 grit) (SIC). Surface roughness and gloss were measured again after polishing. Scanning electron microscopic (SEM) images were taken for one representative specimen from each group pre- and post-polishing. Two-way ANOVA, Bonferroni-adjusted pairwise comparisons and Games-Howell post hoc tests were performed to determine the effectiveness of polishing on roughness and gloss on each material (p < 0.05). Polishing significantly reduced surface roughness (Ra) and increased gloss in CAD/CAM resin composites (p = 0.001), with wide variations ranging between 0.121 and 3.635μm and from 5.9 to 124.9 GU, respectively. SFRC and LU showed smoother surfaces with SOF and SIC (p = 0.001), while LU exhibited higher gloss with OPT. TR had the roughest surfaces and lowest gloss, especially with OPT (p = 0.001). Within the limitations of this study, the new SFRC CAD, polished with Sof-Lex or silicon carbide papers, achieved smoothness and gloss comparable to Lava Ultimate (LU), supporting its potential as an aesthetically restorative material. TR exhibited less favorable surface roughness and gloss upon polishing with the OptraGloss polishing system. Polishing significantly improved the surface properties of CAD/CAM reinforced resin composites; however, the results were material- and protocol-dependent. The findings highlight the importance of selecting appropriate polishing systems to optimize the surface properties of different reinforced resin composites.

The surface condition of bulk-fill resin-based composites plays an essential role in their clinical durability and esthetic performance; however, the combined effect of composite viscosity and finishing and polishing approach has not been fully clarified. This study assessed the influence of composite type (sculptable versus flowable bulk-fill materials) and reduced-step finishing and polishing strategies (one-step versus two-step systems) on surface gloss, roughness, and overall surface quality. Four bulk-fill resin composites-two sculptable (Filtek One Bulk-Fill and Tetric Power Fill) and two flowable (Charisma Bulk Flow One and Fill-Up! )-were finished and polished using one-step systems (Opti1Step and OneGloss) and two-step systems (Sof-Lex diamond spiral wheels and Diacomp Plus Twist). Surface gloss, roughness, and topographic characteristics were assessed using a glossmeter, three-dimensional optical microscopy, and scanning electron microscopy, respectively. Data were analyzed using two-way ANOVA and Tukey's post hoc test. Statistically significant differences were observed among polishing protocols and composite types (p < 0.001). Across all polishing protocols, sculptable bulk-fill composites demonstrated higher gloss values and lower surface roughness compared with flowable materials. Polishing systems incorporating diamond abrasives yielded more favorable surface characteristics than the aluminum-oxide-based system. Notably, for nano-filled sculptable bulk-fill composites, the one-step diamond system Opti1Step produced gloss (up to 89.4 ± 2.8 GU) and roughness outcomes (Sa as low as 0.06μm) comparable to, and in certain cases superior to, those achieved with two-step protocols. Within the limitations of this in vitro investigation, polishing performance was shown to be influenced by the interaction between composite viscosity, filler characteristics, and abrasive type. These results highlight the importance of selecting finishing and polishing protocols based on material-specific properties to optimize surface quality and esthetic outcomes of bulk-fill resin composites. The surface quality of bulk-fill resin composites is influenced by both material composition and polishing protocol. Sculptable bulk-fill materials demonstrate superior polishability compared with flowable composites. Diamond-based polishing systems produce smoother and glossier surfaces, and one-step diamond polishing systems can provide surface quality comparable to multi-step protocols, particularly for nano-filled sculptable bulk-fill composites, while reducing clinical time.

This study aims tooptimize the structural design of porous titaniumalloy scaffolds for mandibular defect repair. It investigates theimpact of different scaffold structures on the biomechanical propertiesof both the scaffold and surrounding bone tissue. Finite element modelsof rabbit mandibular defects were first established. Custom poroustitanium alloy scaffold models were subsequently designed using diamond(DI), cubic (C), and truncated cubic (TC) unit cell structures. Additionally,the structural design of the scaffold can be adjusted based on themechanical properties of the cellular structure. A porous titaniumalloy scaffold featuring a composite unit cell structure was developed.Finite element analysis was then performed to obtain the biomechanicalresponse characteristics of both the scaffolds and the surroundingbone tissue at the defect sites. The unit cell structure significantlyinfluences the stress, strain, and spatial distribution in both thescaffold and the surrounding bone tissue. Comparative analysis demonstratesthat scaffolds with composite unit cell structures possess superioroverall mechanical properties and deliver optimal biomechanical stimulation,thereby promoting new bone regeneration. These findings provide atheoretical basis for optimizing the scaffold’s structuraldesign.

Experimental investigation of prematurely failed cyclone feed pump impeller used in diamond mining applications

Under Pressure: Diamond Mining and Everyday Life in Northern Canada, by Lindsay A. Bell

The paper presents results of investigation of a natural Ib-IaA diamond containing Y-defects from Yubileinaya kimberlite pipe, Yakutia. Analysis of spatial distribution of nitrogen-related A- and C-centers and intensity of infrared (IR) absorption at Raman frequency (1332 cm–1) reveals anticorrelation between these defects. Transmission electron microscopy of a zone with abundant Y-defects shows presence of dislocations in various configurations and numerous clusters of point defects generated by non-conservative dislocation movement. Extended defects with shape resembling thin (1–3 nm) rhombic plates with the largest dimension up to 5–20 nm are observed. Analysis of contrast of these defects shows that they represent nanosized voids (vacancy clusters). It is suggested that the defects were formed by annihilation of dislocation dipoles with subsequent growth by consumption of vacancies produced by non-conservative motion of dislocations. Upon excitation by 787 nm laser, numerous narrow photoluminescence lines are observed between 800–900 nm, their intensity and position show pronounced spatial heterogeneity on scale of few microns. Qualitatively similar behavior was earlier noted for hydrogenated nanodiamonds. It is suggested that the unusual behavior of the luminescence lines may be explained by recombination processes on internal walls of the discovered nanovoids.

To evaluate the effects of different polishing systems on surface roughness (Ra, Rz, Sa), water contact angle and color stability (ΔE₀₀) of a 3D printed permanent resin material. 50 specimens were fabricated using a Saremco Print Crowntec resin with 3D printer and divided into five equal groups: Control (No treatment); Sof-Lex XT; Diacomp Plus Twist; Optiglaze Color Clear; and Ultradent Diamond Polish. Surface roughness was evaluated using a 3D non-contact profilometer, and surface morphology was examined by scanning electron microscopy (SEM). Contact angle was measured using the sessile drop method and analyzed with software. Color change was measured by a spectrophotometer after 15 days of storage in coffee solution. Data were compared by one-way ANOVA and Tukey post hoc test (α= 0.05). Optiglaze showed significantly higher Ra and Rz values than the other polishing systems (P< 0.05). The Ra value of the Diacomp Plus Twist group was lower than the Diamond Polish group; the Sa value was higher than the Sof-Lex XT and Diamond Polish groups (P< 0.05). The Diacomp Plus Twist group exhibited a higher water contact angle than the Optiglaze and Diamond Polish groups (P<0.05). Sof-Lex XT showed higher ΔE₀₀ compared to other polishing systems (P< 0.05). All polishing groups showed lower parameter values than the control group (P< 0.001). These findings indicate that mechanical polishing might enhance the long-term esthetic results and color stability of 3D-printed permanent resin restorations. Clinical studies are required to validate intraoral efficacy.

Interaction of hydrogen with platelets in natural type IaAB diamonds

Abstract The ST2 center is an optically addressable point defect in diamond that facilitates spin initialization and readout at room temperature. However, while this study presents the discovery of photostable ST2 centers first observed in a natural diamond and provides a reliable technique for artificially creating them, its chemical structure remains unknown. To assess the potential of ST2, we map out its basic optical characteristics, reveal its electronic level structure, and quantify the intrinsic transition rates. Furthermore, we investigate its response to microwaves, static magnetic fields, and the polarization of excitation laser light, revealing twelve inequivalent orientations of the ST2 center. Simultaneous exposure to microwaves and static magnetic fields also reveals an exceptionally wide acceptance angle for sensing strong magnetic fields, unlike the well-established NV center, which is sensitive only within a narrow cone aligned with its symmetry axis. This finding establishes the ST2 center as a highly promising candidate for nanoscale quantum sensing.

Synergistic photoelectrochemical polishing of polycrystalline diamond for high-efficiency atomic-level finishing

This study proposes establishing a “gold-backed” loan facility, a scheme that would benefit both the Guyana Gold Board (GGB) and small- to medium-scale gold miners, and, by extension, the economy. The study uses a case study approach, and financial modelling will be integrated to show how participants in the scheme would benefit and, as such, will not be reliant on the informal lending that seems to be pervasive in the gold mining sector. The gold-backed loan will lead to increased gold declarations, higher revenue, and greatly reduced informal borrowing by small- and medium-scale miners. The proposed facility is welcomed by many miners who were interviewed, as well as by their organised body, the Guyana Gold and Diamond Miners Association (GGDMA). Interviews were held with the said Association Executives (GGDMA) and the Key Managers of the Guyana Gold Board; all were very optimistic about the results to be derived from the establishment of the gold-backed loan facility. The findings clearly indicated that the programme would be worth the while, as benefits accrue to both the Guyana Gold Board and the small- and medium-scale miners who are participants in the scheme.

Diamonds offer unique benefits for optical technology development due to their optical, chemical, electrical, mechanical, and thermal properties. These attributes also contribute to their aesthetic appeal, high commercial value, and utility in geological studies. Thus, there is a high demand for nondestructive techniques that enable rapid analysis of natural and synthetic diamonds, as well as diamond-like simulants. Here, we demonstrate sub-micrometer, nondestructive, three-dimensional imaging and spectral analysis of diamonds using multiphoton microscopy (MPM). This approach stimulates nonlinear optical emissions to provide unique insights into the interior structure, fluorescent defects, and formational conditions of diamonds. As a result, MPM can be used to investigate gemstone quality, vacancy centers used in quantum technologies, and the various inclusions and fluorescent emitters that may trace a gemstone provenance and treatment history.

ABSTRACTRationaleDiamonds are generally considered to be metasomatic minerals originating from the Earth's mantle. They formed through the interaction of carbon‐bearing fluids or melts with the surrounding deep lithology. Most knowledge about the formation of diamonds comes from studying their mineral inclusions or stable isotopes. Furthermore, diamonds are the only geological samples that provide insight into the volatile element composition of the Earth's mantle. While hydrogen has been known since the early 1970s to be a common impurity in natural diamonds, only a few studies have provided satisfactory quantitative measurements of its concentration and isotopic composition.MethodsHere, we compare the results obtained using two different techniques involving EA‐IRMS. The first analytical procedure involves H‐pyrolysis and is a modification from existing techniques. The second innovative setup, which has not yet been described, involves diamond combustion followed by hydrogen reduction.ResultsAs diamond test samples are rare, we first analysed analogous samples (graphite) to validate the method, before analysing polycrystalline diamonds (from the Orapa mine in Botswana) with both techniques. After assessing the consistency between the two procedures, we analysed three natural diamonds. The results obtained using both techniques were highly comparable. This confirmed the validity of the H‐Pyrolysis method, which is slightly more sensitive.ConclusionsWe designed and validated a novel methodology to incorporate an additional isotopic record into diamonds, namely, carbon, oxygen and nitrogen, with the objective of tracing the formation process of natural diamonds. Diamond in situ analyses might enhance our comprehension of the deep water cycle. Those measurements require precisely calibrated materials. This technique could provide such references.

Objective: The aim of this study was to investigate the effect of polishing and additional polymerization on color stability in a nanohybrid composite resin. Methods: In this study, 72 composite disk-shaped samples (8*8*2mm) were prepared from a nanohybrid composite (Clearfil Majesty Esthetic, Kuraray, Japan). The samples were polymerized in standard mode (1000 mW/mm2/20sn) with a LED curing device (VALO™Grand, Ultradent, USA) and divided into 3 groups according to polishing treatments; control (unpolished, group1), aluminum oxide discs (group 2/Softex, 3M, USA) and diamond polishing paste (group3/Diamond Polish Mint, Ultradent, USA). Then, in each polishing group, half of the samples remained in the initial polymerization (subgroup a), while the other half were polymerized for an additional 20 s in standard mode (subgroup b). Color was measured with a spectrophotometer (VITA Easy ShadeV, VITAZahnfabrik, Germany) initially and after 1 week of storage in coffee. Color change (ΔE00) was calculated with CIEDE2000 formula. Data were analyzed by Two Way ANOVA, One Way ANOVA, Post-hoc Tukey, and Independent t test in SPSS software (α=.05). Results: The effect of polishing type and additional polymerization on the color stability of the tested material was statistically significant (p&amp;lt;.001). Additional polymerization reduced discoloration in all polishing groups. This reduction was statistically significant in groups 1 (p=.003) and group 2 (p=.001). The least discoloration was obtained in group 3b (4.42±0.81) and the most discoloration was obtained in group 2a (7.98±1.86). Conclusion: Diamond polishing pastes and additional polymerization were found to be beneficial in the color stability of tested material.

Abstract It was by chance that John Morrogh (1849–1901) became an imperial player. Leaving Ireland as an almost penniless young man moulded by the Catholic nationalism of the Christian Brothers, he joined the early diamond rush to Kimberley, South Africa, and returned home twenty years later a director of Cecil Rhodes’s De Beers Consolidated Diamond Mines. He joined the Irish Parliamentary Party (IPP) and his diamond fortune eased his path to a seat in the House of Commons. As the IPP fragmented, he took the side of the anti-Parnellite, Tim Healy, until he resigned his seat and returned to Cork where he became an influential figure in business and local government. This article traces the fortunes and sensibilities of an Irish migrant who in many ways exemplifies Ireland’s ‘ambivalent heritage’ of nationalism and empire. 1

The article discusses the application of landscape design methods and the establishment of directions for the use of the territory in relation to the territory of the Lena ulus (district) of the Republic of Sakha (Yakutia). Currently, the issue of integrating the landscape approach in modern land management is relevant, especially in relation to regions with vulnerable and unique ecosystems subject to intense anthropogenic impact, which includes the studied area. The object of the study is the territory of Lena ulus, located in the south-west of Yakutia. Natural conditions are characterized by extreme climatic conditions: a sharply continental climate, widespread permafrost, as well as the presence of a large waterway - the Lena River and its tributaries. The combination of active industrial development (diamond mining, logging), agricultural development and the growth of human settlements creates a significant burden on natural complexes, which necessitates the use of scientifically sound methods of landscape design to ensure environmental safety, sustainable development of the territory and the preservation of its natural potential. The analysis of the ecological state of landscapes is carried out on the basis of a set of methods: landscape and ecological mapping, field research, remote sensing of the Earth (remote sensing). The assessment of landscape stability in the study is based on an assessment of the ecological state of soils. A generalized SWOT analysis of the landscape system is presented, the ecological framework of the territory is developed, the territory is zoned according to the directions of use. As a result, two areas of use of the territory have been identified on the territory of the Lena Ulus of the Republic of Sakha (Yakutia): "conservation" and "improvement". Based on the analysis of the landscape system, measures are proposed to improve agricultural land. The implementation of the principles of landscape design will help preserve and create a comfortable and safe environment for the population.

The Mirny District is one of the key regions of Yakutia, where significant changes in the population size and ethnic composition occurred from the 1950s to the 1990s, driven by the development of natural resources, particularly diamonds. While numerous scholarly works exist on the industrial development of Western Yakutia and the ethnodemography of Yakutia, a comprehensive study characterizing the ethnodemography of the Mirny District specifically from the early 1950s to the 1990s has not been conducted. This article utilizes archival materials, statistical data, and census data. The relevance of this study stems from the need for a thorough understanding of the historical development of the Mirny District as a key industrial center of Yakutia, formed during the period of intensive diamond mining in the USSR. In the second half of the 20th century, the district underwent a rapid transformation from a sparsely populated area to a dynamic region with high migration activity, which influenced the demographic structure, ethnic composition, and socioeconomic characteristics of the population. In the current context, as Russia faces the challenges of a demographic crisis, urbanization, and interethnic interactions, studying the historical and demographic aspects of the Mirny District is of practical importance. It allows us to identify patterns of migration flows, the population’s adaptation to the extreme conditions of the North, and the impact of industrialization on demographic dynamics. This can be useful for planning regional policy, preserving cultural heritage, and sustainable development in the Arctic regions. Furthermore, in the context of global changes (climate shifts, economic crises), analyzing past experience helps predict future demographic trends and facilitates interdisciplinary research in the fields of history, demography, and regional studies. The main goal of our study. To analyze the development of the Mirny District in the second half of the 20th century through the lens of demographic processes, exploring the relationship between industrial growth, migration flows, and ethnodemographic changes to understand the mechanisms shaping the district’s modern appearance. Objectives: 1. To study the historical context of the formation and development of the Mirny District in the second half of the 20th century, including key events, factors of industrialization, and the role of the diamond mining industry in the district’s formation. 2. To analyze key demographic processes (migration, natural population growth, urbanization), their dynamics, and their impact on the size, age, and gender structure of the Mirny District’s population. 3. To examine ethnic changes and interethnic interactions, including migration flows from various regions of the USSR and the adaptation of the indigenous peoples of Yakutia to new conditions. 4. To assess the role of socioeconomic factors (working conditions, infrastructure, public policy) in demographic shifts and their implications for the district’s social development. 5. Identify the relationships between historical demographic processes and contemporary challenges (demographic crisis, climate change) in order to propose recommendations for the region’s sustainable development.