Columnar Habit Research Articles

Magmatic-hydrothermal evolution of the aquamarine-bearing Yamrang Pegmatite, Eastern Nepal: Insights from beryl, garnet, and tourmaline mineral chemistry

The Ikhabu Pegmatite Field (IPF) in the Nepal Himalaya is a newly discovered rare-element (REL) pegmatite field that hosts the Yamrang pegmatite, the primary source of the famous Nepalese aquamarines. In this contribution, we provide a comprehensive description of the geology of both the IPF and the Yamrang pegmatite, offering insights into the evolutionary stages of the Yamrang pegmatite based on its internal texture and the mineral chemistry of beryl, garnet, and tourmaline. The Yamrang pegmatite is classified as a beryl-columbite subtype of REL pegmatite, exhibiting axial symmetric zonation and is differentiated into five mineralogical-textural zones during magmatic and hydrothermal stages. The magmatic stage involves undercooling, disequilibrium crystallization, and fractional crystallization whereas the hydrothermal stage comprises alkali-enriched fluid exsolution, the formation of miarolitic cavities, and the crystallization of aquamarine. Yamrang aquamarines are enriched in FeO, up to 1.1 wt%, with Fe2+ as the primary chromophore, resulting in their blue color. Two types of beryl have been identified: magmatic beryl in zones 3 and 4 and hydrothermal beryl in miarolitic cavities (zone 5). Magmatic beryls are characterized by their alkali-poor to sodic composition, prismatic to columnar habit, homogeneous texture, and the presence of Fe-Al octahedral substitution. In contrast, hydrothermal beryls belong to the sodic to Li-Cs beryl group, with tabular to acicular habit, weak compositional zoning, and channel-tetrahedral substitution. Yamrang garnet belongs to the almandine-spessartine series, while the tourmalines are Mg-Ca rich dravite-schorl to Fe-Mn rich schorl variety. Alkali-poor to Li-Cs beryl with low REE contents, spessartine garnet (spessartine component, Xsps ∼ 52) with high HREE, and schorl with high Ti but low Li, Pb, and REE contents suggests that the Yamrang Pegmatite is an intermediate-fractionated REL pegmatite. Potential pegmatite evolution indicators for IPF include high alkali, Fe, Mn, and Rb contents in beryl, high Xsps in garnet, and an increase in Li, Fe, Mn, Zn, Ga, and Nb, alongside depletion of Mg, Ca, Ti, and Ta in schorl. The identification of a rare metal pegmatite field in the Nepalese Himalaya reinforces the general rare metal mineralization potential of the entire Himalaya region.

Sensitivity of convectively driven tropical tropopause cirrus properties to ice habits in high-resolution simulations

Abstract. Cirrus clouds that form in the tropical tropopause layer (TTL) can play a key role in vertical transport through the upper troposphere and lower stratosphere, which can significantly impact the radiative energy budget and stratospheric chemistry. However, the lack of realistic representation of natural ice cloud habits in microphysical parameterizations can lead to uncertainties in cloud-related processes and cloud–climate feedbacks. The main goal of this study is to investigate the role of different cloud regimes and the associated ice habits in regulating the properties of the TTL. We compare aircraft measurements from the StratoClim field campaign to a set of numerical experiments at the scale of large-eddy simulations (LESs) for the same case study that employ different microphysics schemes. Aircraft measurements over the southern slopes of the Himalayas captured high ice water content (HIWC) up to 2400 ppmv and ice particle aggregates exceeding 700 µm in size with unusually long residence times. The observed ice particles were mainly of liquid origin, with a small amount formed in situ. The corresponding profile of ice water content (IWC) from the ERA5 reanalysis corroborates the presence of HIWC detrained from deep-convective plumes in the TTL but underestimates HIWC by an order of magnitude. In the TTL, only the scheme that predicts ice habits can reproduce the observed HIWC, ice number concentration, and bimodal ice particle size distribution. The lower range of particle sizes is mostly represented by planar and columnar habits, while the upper range is dominated by aggregates. Large aggregates with sizes between 600 and 800 µm have fall speeds of less than 20 cm s−1, which explains the long residence time of the aggregates in the TTL. Planar ice particles of liquid origin contribute substantially to HIWC. The columnar and aggregate habits are in the in situ range with lower IWC and number concentrations. For all habits, the ice number concentration increases with decreasing temperature. For the planar ice habit, relative humidity is inversely correlated with fall speed. This correlation is less evident for the other two ice habits. In the lower range of supersaturation with respect to ice, the columnar habit has the highest fall speed. The difference in ice number concentration across habits can be up to 4 orders of magnitude, with aggregates occurring in much smaller numbers. We demonstrate and quantify the linear relationship between the differential sedimentation of pristine ice crystals and the size of the aggregates that form when pristine crystals collide. The slope of this relationship depends on which pristine ice habit sediments faster. Each simulated ice habit is associated with distinct radiative and latent heating rates. This study suggests that a model configuration nested down to LES scales with a microphysical parameterization that predicts ice shape evolution is crucial to provide an accurate representation of the microphysical properties of TTL cirrus and thus the associated (de)hydration process.

Formation of Esseneite and Kushiroite in Tschermakite-Bearing Calc-Silicate Xenoliths Ejected in Alkali Basalt

Skarnoid calc-silicate xenoliths composed of anorthite, clinopyroxene and Mg-Al spinel occur in alkali basalts of the Pliocene-Pleistocene intra-plate magmatic province in the northern part of the Pannonian Basin. Randomly oriented and elongated pseudomorphs are tschermakite crystals replaced by olivine, spinel and plagioclase. The relict amphibole within the pseudomorphs is characterized by high VIAl, between 1.95 and 2.1, and very low occupancy of the A-site (<0.1 apfu)—these features are rarely found in nature and are thought to be diagnostic of high-pressure metamorphic rocks. Pyroxene compositions plot along continuous mixing line extending from nearly pure diopside-augite towards a Ca(Fe3+Al)AlSiO6 endmember with an equal proportion of VIAl3+ and Fe3+. Concentrations of kushiroite CaAlAlSiO6 endmember, up to 47.5 mol%, are the highest recorded in terrestrial samples. The AlFe3+-rich pyroxenes originated at the expense of diopside-augite during the interaction with carbonate-aluminosilicate melt. Forsterite (Fo72–83) and hemoilmenite with up to 32 mol% geikielite (9.3 wt% MgO) also crystallized from the melt, leaving behind the residual calcic carbonate with minor MgO (1–3 wt%). Columnar habit of neoformed olivine growing across diopside-augite layers indicates rapid crystallization from eutectic liquid. Euhedral aragonite and apatite embedded in fine-grained calcite or aragonite groundmass indicate slow crystallization of the residual carbonatite around the calcite-aragonite stability boundary. Corundum exsolutions in rock-forming anorthite are products of superimposed low-pressure pyrometamorphic reworking during transport in alkali basalt. Concomitant alkali metasomatism produced neoformed interstitial sodalite, nepheline, sanidine, albite, biotite, Mg-poor ilmenite (10–18 mol% MgTiO3), Ti-magnetite and fluorapatite. Olivine-ilmenite-aragonite-calcite thermobarometry returned temperatures of 770–860 °C and pressures of 1.8–2.1 GPa, whereas plagioclase-amphibole thermobarometer yielded 781 ± 13 °C and 2.05 ± 0.03 GPa. The calculated pressures correspond to depths of 60–70 km. The calc-silicate xenoliths are most likely metamorphosed marbles; however, a magmatic protolith (metagabbro, metaanorthosite) cannot be ruled out owing to high Cr contents in spinels (up to 30 mol% chromite) and abundant Cu-sulfides.

Brief results and prospects of apple breeding at VNIISPK

As a result of 65 years of intensive large-scale apple breeding work, the Russian Research Institute of Fruit Crop Breeding (VNIISPK) created and included in the State Register of Breeding Achievements 56 apple cultivars of different fruit ripening periods. Some of them are already widely known and occupy large areas in industrial and amateur gardens. Among these cultivars, Venyaminovskoye, Veteran, Rozhdestvenskoye and Sinap Orlovsky are approved for use in four regions of the Russian Federation; Kandil Orlovsky, Kulikovskoye, Orlik and Orlovskoye Polosatoye are grown in three regions; 10 cultivars are zoned in two regions of Russia; the remaining 37 cultivars are allowed for use so far in one region of the country. For the first time in Russia and in the world, 17 triploid apple cultivars were created from intervalent crosses. These cultivars are characterized by more regular fruiting and more beautiful and larger fruits. Some of them are immune to scab. In total, more than 20 apple cultivars immune to scab have been created, including the first domestic scab-immune cultivar Imrus (immune russian). The long-term work has shown that only a large interdisciplinary team can create apple cultivars that meet the ever-increasing production requirements. The disadvantage in our breeding work with apples, as well as in other breeding institutions, is that it usually takes too much time to create a cultivar (often more than 25 years). As our experience shows, it took no more than 20 years to create individual cultivars: Rozhdestvenskoye – 16 years, Priokskoye – 18 years, Imrus and Poesia – 19 years, to create Alexandr Boyko, Venyaminovskoye, Kandil Orlovsky, Maslovskoye, Solnyshko, Stroevskoye, and Pamyaty Khitrovo it took 20 years. The greatest number of years was spent on the creation of the following cultivars: Pepin Orlovsky – 48 years, Orlovskaya Zarya – 45 years, Pamyat Voinu and Radost Nadezhdy – 38 years, Kulikovskoye – 37 years, Sinap Orlovsky – 34 years, Den Pobedy – 33 years. This article presents techniques that accelerate the selection process in apples. In the coming years, the goal is to obtain triploid cultivars that are immune to scab and have columnar habit (“three in one”).

Foraminiferal micro-buildups (“reefs”) in the Wuchiapingian basin facies of the basal Zechstein carbonates in western Poland

Encrusting foraminifers locally can play an essential reef-forming role such as in the Carnian fossiliferous Hallstatt Limestones of Austria where a dense succession of hardgrounds occurs with numerous small buildups (up to 2 cm high) composed of sessile foraminifers. Similar foraminiferal micro-buildups occur in a 10-cm-thick bed in the basinal facies in the basal Zechstein (Upper Permian) strata in the Radlin 60 borehole, in western Poland. Foraminiferal micro-buildups of presumably columnar habit account for up to a half of the volume. The growth of columns was interrupted by hiatal surfaces, although usually the growth of columns was restored afterwards. In the upper part of the bed with foraminiferal micro-buildups, the foraminiferal encrustations become visibly less abundant, and in most cases, they have a shape of less regular masses. The bed with foraminiferal micro-buildups abounds in closely spaced discontinuity (hiatal) surfaces, occasionally encrusted by foraminifers. Tubular foraminifers in the bed with foraminiferal micro-buildups are accompanied by various encrusting organisms, possibly microbes; they are grouped under the name Palaeonubecularia. In the intercolumnar spaces, common Midiella sp. occur. During deposition, the conditions were mostly suboxic, and various types of ferruginous morphs, common in the lower part of the bed, suggest that dysoxic–anoxic interfaces produced various microaerophilic environments for iron-bacteria. The environmental conditions during the deposition of the upper part of the bed were very similar to those characterizing the starved basin environment in which the bioclastic-peloidal and oncoidal sediments in the Zechstein Limestone have been formed. In turn, the lower part of the bed registers the transition from normal (= not starved) marine conditions, with a clear chemocline, to the starved basin conditions. The deposition of the bed was coeval with the Kupferschiefer deposition based on the correlation of δ13C curves, which implies that the previous stratigraphical concept of basal Zechstein strata has to be re-evaluated.

Mineralogical classification and crystal water characterisation of beryl from the W–Sn–Be occurrence of Xuebaoding, Sichuan province, western China

AbstractBeryl from Xuebaoding, Sichuan Province, western China is known for its unusual tabular habit and W–Sn–Be paragenesis in a greisen-type deposit. The crystals are typically colourless transparent to pale blue, often with screw dislocations of hexagonal symmetry on the (0001) crystal faces. Combining electron microprobe analyses and laser ablation inductively coupled plasma mass spectrometry with single-crystal X-ray diffraction (XRD), correlated with Raman and micro-infrared (IR) spectroscopy and imaging, the crystal chemical characteristics are determined. The contents of Na+ (0.24–0.38 atoms per formula unit (apfu)) and Li+ up to 0.38 apfu are at the high end compared to beryl from other localities worldwide. Li+ substitution for Be2+ on the tetrahedral (T2) site is predominantly charge balanced by Na+ on the smaller channel (C2) site, with Na+ ranging from 91.5% to 99.7% (apfu) of the sum of all other alkali elements. Cs+ and minor Rb+ and K+ primarily charge balance the minor M2+ substitution for Al3+ at the A site; all iron at the A site is suggested to be trivalent. The a axis ranges from 9.2161(2) to 9.2171(4) Å, with unit-cell volume from 678.03(3) to 678.48(7) Å3. The c/a ratio of 1.0002–1.0005 is characteristic for T2-type beryl with unit-cell parameters controlled primarily by Be2+ substitution. Transmission micro-IR vibrational spectroscopy and imaging identifies coordination of one or two water molecules to Na+ (type IIs and type IId, respectively) as well as alkali free water (type I). Based on IR absorption cross section and XRD a C1 site water content of 0.4–0.5 apfu is derived, i.e. close to 50% site occupancy. Secondary crystal phases with a decrease in Fe and Mg, yet increase in Na, suggest early crystallisation of aquamarine, with goshenite being late. With similar crystal chemistry to beryl of columnar habit from other localities worldwide, the tabular habit of Xuebaoding beryl seems to be unrelated to chemical composition and alkali content.

Structure of an Atmospheric River Over Australia and the Southern Ocean: II. Microphysical Evolution

AbstractAn atmospheric river affecting Australia and the Southern Ocean on 28–29 January 2018 during the Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study (SOCRATES) is analyzed using nadir‐pointing W‐band cloud radar measurements and in situ microphysical measurements from a Gulfstream‐V aircraft. The AR had a two‐band structure, with the westernmost band associated with a cold frontal boundary. The bands were primarily stratiform with distinct radar bright banding. The microphysical evolution of precipitation is described in the context of the tropical‐ and midlatitude‐sourced moisture zones above and below the 0°C isotherm, respectively, identified in Part I. In the tropical‐sourced moisture zone, ice particles at temperatures less than −8°C had concentrations on the order of 10 L−1, with habits characteristic of lower temperatures, while between −8°C and −4°C, an order of magnitude increase in ice particle concentrations was observed, with columnar habits consistent with Hallett‐Mossop secondary ice formation. Ice particles falling though the 0°C level into the midlatitude‐sourced moisture region and melting provided “seed” droplets from which subsequent growth by collision‐coalescence occurred. In this region, raindrops grew to sizes of 3 mm and precipitation rates averaged 16 mm hr−1.

A rapid real‐time PCR assay for detecting columnar growth in apples (Malus × domestica)

AbstractColumnar growth in apples can have considerable positive consequences for orchard maintenance, but the lack of columnar cultivars producing fruits with desired market quality prevents their broader utilization in orchards. New crossings focused on their breeding are therefore conducted throughout the world every year. Unfortunately, the reliable discrimination between columnar growth and normal phenotype is difficult until seedlings are 2–3 years of age. However, molecular marker–assisted selection (MAS) can be used in seedlings several weeks old providing immense help in breeding programmes focused on columnar apple production. Here, we describe a rapid and reliable method for the detection of both wild‐type (WT) and columnar (Co) alleles originating from ‘McIntosh Wijcik’ in a single reaction using a real‐time PCR allelic discrimination approach. Our assay was tested in 130 genotypes (80 normal and 50 columnar habit) from various crossings and their parents, and in all cases, genotype corresponded to phenotype. The assay is thus suitable for laboratories interested in high‐throughput MAS for columnar tree habit breeding.

Genes involved in strigolactone biosyntheses and their expression analyses in columnar apple and standard apple

Columnar apple is a valuable resource for genetic improvement of cultivated apples due to its special tree architecture. Strigolactones (SLs) are a novel class of plant hormones controlling shoot branching. The content of SLs is higher in columnar apple than in standard apples. In this study, the members of major gene families involved in SLs biosynthesis and signaling were identified from apple genomic sequences and their expression profiles were characterized in columnar and standard apples using reverse transcription quantitative polymerase chain reactions. In comparison with standard apple, the higher expressions of MORE AXILLARY GROWTH genes MdMAX3-1 and MdMAX4-4 were detected in both buds and shoots of columnar apple but the expression of DWARF gene MdD53-4 showed a lower expression in columnar apple. Overexpression of Columnar gene MdCo31 in tobacco increased SLs content and weakened the inhibition of SLs signal transduction by increasing expression of MAX3 and down-regulating the transcription of D53. Thus MdCo31 could be a strong candidate gene for the control of columnar habit.

ПОПОЛНЕНИЕ ГЕНЕТИЧЕСКОЙ КОЛЛЕКЦИИ ЯБЛОНИ ФГБНУ ВНИИСПК ДЛЯ ИСПОЛЬЗОВАНИЯ В СЕЛЕКЦИИ

A brief description of genetic collection of apple in the Russian Research Institute of Fruit Crop Breeding (VNIISPK) is given in this article. The collection is annually saved and replenished with the introduced apple varieties from various breeding institutions of Russia, CIS, Europe, America and Australia as well as varieties and hybrids of VNIISPK breeding. At the Institute in 01.01.2019, the apple gene pool consisted of 830 accessions and 350 selected seedlings for further study and selection of new source material for breeding. In the genetic collection of the Institute there are sources and donors for apple breeding for columnar habit, winter hardiness, precocity and high productivity, long shelf life of fruit, high resistance and immunity to scab as well as donors of diploid gametes for breeding on a polyploidy level, sources and donors of high content of sugars, titrate acids and biologically active substances (ascorbic acid and P-active substances). Creation, preservation, study and replenishment of the gene pool are a priority and actual direction of research.

Сорта яблони селекции ВНИИСПК как источники и доноры хозяйственно ценных признаков

Brief descriptions of economically valuable characteristics of 45 apple varieties breeding in All-Russian Research Institute of Fruit Crop Breeding are given in this article. Long-term study of varieties allowed to revealed from a large set of varieties donors and sources of valuable traits. The varieties Afrodita, Bolotovskoe, Veniaminovskoe, Vostorg, Zdorovie, Ivanovskoe, Kandil Orlovsky, Kurnakovskoe, Orlovskoe Polesie, Pamiati Hitrovo, Svezhest, Sozvezdie, Solnyshko, Stroevskoe and Jubiley Moskvy have been selected as donors of immunity to scab. The varieties Vostorg, Girlianda, Orlovskaya Yesenia, Poezia and Priokskoe have been selected as donors of columnar tree habit. The varieties Bolotovskoe, Veteran, Girlianda, Imrus, Orlik, Ranneye Aloe, Sozvezdie, Sokovinka and Yubiley Moskvy can be sources of higher winter hardiness. Columnar apple varieties of the Institute as well as Veteran, Svezhest and Utrennya Zvezda are sources of high productivity. The varieties Blagodat, Zhelannoe, Morozovskoe, Orlovskoe Polosatoe, Pamiat Voinu and Slavianin are high marketable qualities of fruit; the varieties Afrodita, Blagodat, Veniaminovskoe, Veteran, Orlik, Osipovskoe, etc. are high taste qualities of fruit; Veteran, Imrus, Kulikovskoe and Svezhest are durable fruit storage; the varieties Zarianka, Pepin Orlovsky, Veteran, Ivanoskoe and Vita are higher content of ascorbic acid in fruit (14,5-21,4 mg/100 g); the varieties Afrodita, Radost Nadezhdy, Bolotovskoe, Vita, Kandil Orlovsky, Pamiati Hitrovo, Pamit Semakinu, Utrenya Zvezda and Chistotel are high content of P-active substances in fruit (over 450 mg/100 g); the varieties Bolotovskoe, Orlovim, Orlinka, Osipovskoe, Priokskoe, Rozhdestvenskoe, Girlianda and Vostorg are sources of variety suitability for juice production. Some of these varieties have already been successfully used in Russia and a number of other countries as donors or sources for the creation of varieties of new generation.

Development of triploid apple cultivars as a priority in selection

We carried out a detailed examination of the preliminary breeding (prebreeding) techniques during the development of triploid apple cultivars. The characteristics of diploid gamete donors are summarized. It should be noted that at times donors of diploid gametes with the necessary important traits must not only be selected among the existing tetraploid cultivars but also need to be specially bred, in particular, in cases when there are no cultivars and genotypes (donors of diploid gametes) with the given traits in nature. We developed the 30-47-88 apple form (Liberty × 13-6-106) by selection breeding. The 30-47-88 form is at once a donor of diploid gametes and of scab immunity (V f ). During 1970–2015, the following work was carried out on apple breeding using polyploidy: 455 crossing combinations were performed; 660000 flowers were artificially pollinated; 124700 hybrid seeds were obtained; and 47900 one-year-old seedlings were grown, from which, after multiple rejections, 13200 seedlings were planted in breeding orchards. For the first time in Russia, ten apple cultivars (Avgusta, Aleksandr Boiko, Bezhin Lug, Vavilovskoye, Dariona, Maslovskoye, Orlovsky Partizan, Osipovskoye, Patriot, and Yablochny Spas) are developed from intervalence crossings and regionalized. It is stated that apple cultivars developed at the All-Russian Research Institute of Fruit Crop Breeding (VNIISPK) are characterized as a rule by a high level of productivity, better fruit marketability, greater resistance to scab, and higher autogamy. Apple cultivars combining triploidy and scab immunity are developed. Promising breeding work is being performed for apple cultivars combining triploidy, scab immunity, and columnar habit (Co). Brief characteristics are provided for the obtained triploid and scab immune cultivars, Vavilovskoye and Yablochny Spas, developed from intervalence crossings, as well as three triploid cultivars obtained from crossing diploid cultivars. It is noted that triploid apple cultivars developed at VNIISPK are inferior to none of the foreign cultivars, based on a complex of commercial traits, and they significantly excel foreign cultivars in adaptability. Our apple cultivars may contribute to the import substitution of fruit production in Russia.

Selection of promising apple genotypes for columnar growth habit and scab resistance using diagnostic DNA markers

Monogenic scab resistance and columnar growth habit are important breeding traits of apple. The use of molecular markers very accurately determines the presence of necessary genes in the genome early during ontogenesis and reduces the time of selection. The purpose of this study was molecular genetic testing of initial forms of apple and hybrid seedlings of apple to identify carriers of the target alleles of genes for monogenic scab resistance (Rvi6) and columnar growth habit (Co) and the clarification of the pattern of inheritance of the Co and Rvi6 genes in hybrid progeny populations. This paper presents the results of molecular genetic analysis of varieties Valuta, Uspenskoe, Belarusskoe sladkoe and seedlings of the Valuta×Uspenskoe and Valuta×Belarusskoe sladkoe hybrid families for genes controlling columnar growth habit (Co) and scab resistance (Rvi6). The presence of the dominant allele of the Co gene was diagnosed with primers 29f1 and JWI1r flanking the 5’-end of the insert at the Co locus controlling columnar genotypes. Allelic status of the Rvi6 gene was determined with the AL07-SCAR marker mapping at about 0.2 cM from the Rvi6 locus. The correlation frequency of inheritance of the allelic states of these genes has been determined. Valuta×Uspenskoe crosse yielded 48.1 % columnar genotypes and 77.8 % scab-immune genotypes; Valuta×Belarusskoe sladkoe crosses, 46.8 % and 68.0 %, respectively. The observed segregation conforms to the expected Mendelian ratios: 1:1 for columnar habit and 3:1 for scab resistance. The joint inheritance of columnar growth habit and monogenic resistance to scab has been analyzed. The hybrid seedlings that had the dominant Co allele together with the Rvi6 gene in the homozygous dominant state (Rvi6 Rvi6) in their genome have been identified, which can significantly intensify the selection process and run it into 100 % of hybrid seedlings with monogenic scab resistance and up to 50 % of genotypes with columnar growth habit.

Use of molecular markers for identification of genotypes of columnar apple trees

This paper presents the results of identification of columnar habit in apple trees using molecular markers 29f3 and 29f1. In the genome of varieties Strela, Teleimon, Kaskad, Geizer, Zelenyi Shum, Priok-skoe, and Gotika, an insertion determining the columnar crown habit in apple trees was identified in the near-gene region of the Co locus. This insertion is absent in the genome of noncolumnar apple tree varieties.

Growth and dislocation studies of β-HMX

BackgroundThe defect structure of organic materials is important as it plays a major role in their crystal growth properties. It also can play a subcritical role in “hot-spot” detonation processes of energetics and one such energetic is cyclotetramethylene-tetranitramine, in the commonly used beta form (β-HMX).ResultsThe as-grown crystals grown by evaporation from acetone show prismatic, tabular and columnar habits, all with {011}, {110}, (010) and (101) faces. Etching on (010) surfaces revealed three different types of etch pits, two of which could be identified with either pure screw or pure edge dislocations, the third is shown to be an artifact of the twinning process that this material undergoes. Examination of the {011} and {110} surfaces show only one type of etch pit on each surface; however their natural asymmetry precludes the easy identification of their Burgers vector or dislocation type. Etching of cleaved {011} surfaces demonstrates that the etch pits can be associated with line dislocations. All dislocations appear randomly on the crystal surfaces and do not form alignments characteristic of mechanical deformation by dislocation slip.ConclusionsCrystals of β-HMX grown from acetone show good morphological agreement with that predicted by modelling, with three distinct crystal habits observed depending upon the supersaturation of the growth solution. Prismatic habit was favoured at low supersaturation, while tabular and columnar crystals were predominant at higher super saturations. The twin plane in β-HMX was identified as a (101) reflection plane. The low plasticity of β-HMX is shown by the lack of etch pit alignments corresponding to mechanically induced dislocation arrays. On untwinned {010} faces, two types of dislocations exist, pure edge dislocations with b = [010] and pure screw dislocations with b = [010]. On twinned (010) faces, a third dislocation type exists and it is proposed that these pits are associated with pure screw dislocations with b = [010].Graphical abstractEtch pits on the twinned (010) face of β-HMX.

The columnar mutation (“Co gene”) of apple (Malus × domestica) is associated with an integration of a Gypsy-like retrotransposon

The columnar growth habit of apple trees (Malus × domestica Borkh.) is a unique plant architecture phenotype that arose as a bud sport mutation of a McIntosh tree in the 1960s. The mutation (“Co gene”) led to trees (McIntosh Wijcik) with thick, upright main stems and short internodes that generate short fruit spurs instead of long lateral branches. Although Co has been localized to chromosome 10, in a region approximately between 18.5 and 19 Mb, its molecular nature is unknown. In a classical positional cloning approach in combination with the analysis of NGS data, we cloned and analyzed the Co region. Our results show that the insertion of a Ty3/Gypsy retrotransposon into a non-coding region at position 18.8 Mb is the only detectable genomic difference between McIntosh and McIntosh Wijcik and is found in all columnar cultivars. The genetic effect of the insertion is unclear; however, Illumina® RNA-seq data of McIntosh and McIntosh Wijcik suggest that the columnar growth habit is associated with differential expression of the retrotransposon transcript, causing changes in the expression levels of many protein coding genes. The mechanism by which the Gypsy retrotransposon is involved in generating the columnar habit is not yet clear; our findings form the basis for tackling this question.

Evidence for regulation of columnar habit in apple by a putative 2OG‐Fe(II) oxygenase

Understanding the genetic mechanisms controlling columnar-type growth in the apple mutant 'Wijcik' will provide insights on how tree architecture and growth are regulated in fruit trees. In apple, columnar-type growth is controlled by a single major gene at the Columnar (Co) locus. By comparing the genomic sequence of the Co region of 'Wijcik' with its wild-type 'McIntosh', a novel non-coding DNA element of 1956 bp specific to Pyreae was found to be inserted in an intergenic region of 'Wijcik'. Expression analysis of selected genes located in the vicinity of the insertion revealed the upregulation of the MdCo31 gene encoding a putative 2OG-Fe(II) oxygenase in axillary buds of 'Wijcik'. Constitutive expression of MdCo31 in Arabidopsis thaliana resulted in compact plants with shortened floral internodes, a phenotype reminiscent of the one observed in columnar apple trees. We conclude that MdCo31 is a strong candidate gene for the control of columnar growth in 'Wijcik'.

Effects of a structurally related substance on the crystallization of paracetamol

Paracetamol (PCM) was crystallized from an isopropanol (IPA) solution containing various small amounts of metacetamol as an additive. The effect on the nucleation kinetics was studied by measuring the induction time to nucleation and the metastable zone width using focused beam reflectance measurements (FBRM) and attenuated total reflectance (ATR-UV/Vis) spectroscopy. Both the induction time and the metastable zone width were expressed as functions of the additive concentration. Small amounts of metacetamol (1–4 mol-%) were found to cause significant inhibition to the nucleation by extending both the induction time and the metastable zone width. A progressive change in the morphology of the paracetamol crystals from tabular to columnar habit was observed with increasing metacetamol concentration. The solvent also had a significant effect on the size of the paracetamol crystals as smaller crystals were obtained in IPA than in aqueous solution. The dissolution rate of paracetamol was improved by the incorporation of metacetamol with 4 mol-% having the most effect. A supersaturation control (SSC) approach was implemented for the PCM-IPA system with and without metacetamol in an attempt to control and obtain larger metacetamol-doped paracetamol crystals.

Five New Species of South AmericanGentianella(Gentianaceae)

Five new species of Gentianella Moench (Gentianaceae) are described from western South America. Gentianella decemnectaria J. S. Pringle, from Peru, is characterized by decumbent stems and nearly rotate corollas with 10 nectaries per corolla. Gentianella pluvialis J. S. Pringle, from Bolivia, is similar to G. florida (Griseb.) Holub, differing in its larger flowers with bright yellow corollas. Gentianella pyrostelium J. S. Pringle, from Peru, is characterized by its columnar habit and red and yellow, scarcely opening corollas. Gentianella rugicalyx J. S. Pringle, from Peru, differs from G. paludicola (Gilg) J. S. Pringle in its wider, abruptly acute calyx lobes and corolla tube that widens more gradually, and from G. persquarrosa (Reimers) J. S. Pringle in its leafier stems and glabrous corollas. Gentianella sanchezii J. S. Pringle, from Peru, is characterized by slender, clustered stems arising from a persistent rosette, pedicels mostly longer than the internodes, and widely funnelform, purplish pink corollas.

Pinus contorta var. yukonensis var. nov. (Pinaceae) from south-central Yukon, Canada

Pinus contorta Douglas ex Loudon var. yukonensis W. L Strong (Yukon pine), a new variety, is described from south–central Yukon, Canada. It is a stout tree with long lower branches, often with paired lower and forked upper stems, and weakly platy to smooth gray bark on the lower stem, when < 70 years old; with bark on the lower stem becoming furrowed and platy on older trees. This contrasts with the narrow columnar habit, simple stem, and scaly bark associated with the more common inland var. latifolia. In several respects, var. yukonensis is more similar to var. contorta (a coastal variant), although occupying a different ecological regime and spatially disjunct (i.e., a high latitude and high elevation variant). Variety yukonensis may represent the taxon alluded to in previous leaf oil terpene and genetic studies, and a possible Beringian survivor.