Formation Of Column Research Articles

Production of Wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column in medaka

The floor plate is a key organizer that controls the specification of neurons in the central nervous system. Here, we show a new role of the floor plate: segmental pattern formation of the vertebral column. Analysis of a spontaneous medaka mutant, fused centrum (fsc), which exhibits fused centra and the absence of the intervertebral ligaments, revealed that fsc encodes wnt4b, which was expressed exclusively in the floor plate. In fsc mutants, we found that wnt4b expression was completely lost in the floor plate and that abnormal conversion of the intervertebral ligament cells into osteoblasts appeared to cause a defect of the intervertebral ligaments. The establishment of the transgenic rescue lines and mosaic analyses allowed the conclusion to be drawn that production of wnt4b by floor plate cells is essential for the segmental patterning of the vertebral column. Our findings provide a novel perspective on the mechanism of vertebrate development.

Enantiopure tert-butyl(phenyl)phosphine oxide. Chirality-recognition ability and mechanism

When enantiopure tert-butyl(phenyl)phosphine oxide 1 was used as a resolving agent, it showed an acceptable to good chirality-recognition ability for several kinds of racemic carboxylic acids 2. A study on a chirality-recognition mechanism based on X-ray crystallographic analyses of the diastereomeric complexes of 2 with 1 revealed that the complex crystals consisted of helical columns and that 1 was not responsible for the formation of the helical column and occupied a void between the columns; although 1 interacted with 2 via a hydrogen bond to primarily form a pair with 2, the complex crystals were mainly stabilized by the accumulation of weak interactions, such as CH/π, π/π and CH⋯O interactions, between 1/ 1, 1/ 2 and 2/ 2.

The OFF-pathway dominance of P2X2-purinoceptors is formed without visual experience

Visual input in the critical period is an important determinant of the functions of the visual system, affecting for example the formation of the ocular dominance column in the visual cortex. The final map of columnar organization is usually determined by plastic changes in the critical period, but organization is distorted without adequate visual input. Here, we examined whether formation of the OFF-pathway dominance of P2X(2)-purinoceptor signaling in the mouse retina is the result of visual experience. The P2X(2)-purinoceptor signaling pathway developed during the critical period. However, visual experience in this period produced no plastic change in the formation of the OFF-pathway dominance of P2X(2)-purinoceptor signaling. Our findings suggest that the OFF-pathway dominance of P2X(2)-signaling in the mouse retina is intrinsically programmed.

Study of the effect of current rise time on the formation of the precursor column in cylindrical wire array Z pinches at 1 MA

The limited understanding of the mechanisms driving the mass ablation rate of cylindrical wires arrays is presently one of the major limitations in predicting array performance at the higher current levels required for inertial confinement fusion (ICF) ignition. Continued investigation of this phenomenon is crucial to realize the considerable potential for wire arrays to drive both ICF and inertial fusion energy, by enabling a predictive capability in computational modeling. We present the first study to directly compare the mass ablation rates of wire arrays as a function of the current rise rate. Formation of the precursor column is investigated on both the MAPGIE (1 MA, 250ns [Mitchell et al., Rev. Sci. Instrum. 67, 1533 (1996)]) and COBRA (1 MA, 100ns [Greenly et al., Rev. Sci. Instrum. 79, 073501 (2008)]) generators, and results are used to infer the change in the effective ablation velocity induced by the rise rate of the drive current. Laser shadowography, gated extreme ultraviolet (XUV) imaging, and x-ray diodes are used to compare the dynamical behavior on the two generators, and X-pinch radiography and XUV spectroscopy provide density evolution and temperature measurements respectively. Results are compared to predictions from an analytical scaling model developed previously from MAGPIE data, based on a fixed ablation velocity. For COBRA the column formation time occurs at 116±5 ns and for Al arrays and 146±5 ns for W arrays, with Al column temperature in the range of 70–165 eV. These values lie close to model predictions, inferring only a small change in the ablation velocity is induced by the factor of 2.5 change in current rise time. Estimations suggest the effective ablation velocities for MAGPIE and COBRA experiments vary by a maximum of 30%.

Studies on the Behavior of Single and Group of Geosynthetic Encased Stone Columns

The stone columns (or granular piles) are increasingly being used as ground reinforcement elements for supporting a wide variety of structures including buildings and flexible structures. The stone columns derive their load capacity from the confinement offered by the surrounding soil. In very soft soils this lateral confinement may not be adequate and the formation of the stone column itself may be doubtful. Wrapping the individual stone columns with suitable geosynthetic is one of the ideal forms of improving the performance of stone columns. This type of encasement by geosynthetic makes the stone columns stiffer and stronger. In addition, encasement prevents the lateral squeezing of stones in to the surrounding clay soil and vice versa, preserves drainage function of the stone column and frictional properties of the aggregates. In spite of many advantages, the behavior and the mechanism of the geosynthetic encased stone columns is not thoroughly understood. This paper investigates the qualitative and quantitative improvement of individual load capacity of stone column by encasement through laboratory model tests conducted on stone columns installed in clay bed prepared in controlled condition in a large scale testing tank. The load tests were performed on single as well as group of stone columns with and without encasement. Tests were performed with different geosynthetics for the encasement of stone column. The results from the load tests indicated a clear improvement in the load capacity of the stone column due to encasement. The increase in the axial load capacity depends very much upon the modulus of the encasement and the diameter of the stone column. The increase in the stress concentration on the stone columns due to encasement was also measured in the tests. The results from the tests were used to develop the design guidelines for the design of geosynthetic encasement for the given load and settlement.

Recent advances in the understanding of homogeneous dielectric barrier discharges

This paper is a state of the art of the understanding on the physics of homogeneous dielectric barrier discharges at atmospheric pressure. It is based on the analysis of present and previous work about the behavior of these discharges and the conditions to get them. Mechanisms controlling the homogeneity during gas breakdown and discharge development are successively discussed. The breakdown has to be a Townsend one, the ionization has to be slow enough to avoid a large avalanche development. During the breakdown, the discharge homogeneity is related to the ratio of the secondary emission at the cathode (γ coefficient) on the ionization in the gas bulk (α coefficient). Higher is this ratio, higher is the pressure × gas gap product (Pd) value for which a Townsend breakdown is obtained. Among the phenomena enhancing the secondary emission there is the negative charge of the dielectric on the cathode surface, the trapping of ions in the gas and the existence of excited state having a long lifetime compared to the time between two consecutive discharges. The first phenomenon is always present when the electrodes are covered by a solid dielectric, the second one is related to the formation of a positive column and the third one is specific of the gas. During the discharge development, the homogeneity is mainly controlled by the voltage or the current imposed by the electrical circuit/electrode configuration and by the gas ability to be slowly ionized. Larger is the contribution of a multiple step ionization process like Penning ionization, higher will be the working domain of the discharge. A decrease of the gas voltage during the discharge development is a solution to enhance the contribution of this process. After 20 years of research a lot of mechanisms have been understood however there is still open questions like the nature of the Inhibited homogeneous DBD, surface energy transfers, role of attachment and detachment...

Motor Neurons with Axial Muscle Projections Specified by Wnt4/5 Signaling

SummaryAxial muscles are innervated by motor neurons of the median motor column (MMC). In contrast to the segmentally restricted motor columns that innervate limb, body wall, and neuronal targets, MMC neurons are generated along the entire length of the spinal cord. We show that the specification of MMC fate involves a dorsoventral signaling program mediated by three Wnt proteins (Wnt4, Wnt5a, and Wnt5b) expressed in and around the floor plate. These Wnts appear to establish a ventralhigh to dorsallow signaling gradient and promote MMC identity and connectivity by maintaining expression of the LIM homeodomain proteins Lhx3/4 in spinal motor neurons. Elevation of Wnt4/5 activity generates additional MMC neurons at the expense of other motor neuron columnar subtypes, whereas depletion of Wnt4/5 activity inhibits the production of MMC neurons. Thus, two dorsoventral signaling pathways, mediated by Shh and Wnt4/5, are required to establish an early binary divergence in motor neuron columnar identity.

Chronology of the 2007 eruption of Stromboli and the activity of the Scientific Synthesis Group

On 27 February 2007, at 12.49 GMT, a new eruption of Stromboli took place with the effusion of a lava flow from a fracture cutting the flank of the NE cone, which rapidly reached the sea. The eruption had been heralded by an increase in the amplitude of tremor and flank movement since at least the 14th of February. Short-term precursors were an increase in the rate of occurrence of small landslides within the “Sciara del Fuoco” scar on the North-western flank of the volcano. A new effusive vent opened at 18.30 GMT on the Sciara del Fuoco at an height of 400 m asl. The new lava emission caused the sudden termination of the summit flow and initiated a period of non-stationary lava outpouring which ended on 2 April, 2007. The eruption has been characterized by a rapid decrease in the eruption rate after the first days and subsequently by episodic pulse increases. On the 15th of March, the increase in lava outpouring, monitored by a thermal camera, heralded by 9 min the occurrence of a violent paroxysmal explosion with the formation of an impulsive eruption column and the emission of small pumices mingled with black scoriae. The pumice had a bulk composition similar to that of the lava and of the black scoriae, but with a distinct lower content of phenocrysts. A similar feature has been repeatedly observed during the major explosive paroxysms of Stromboli. Short term precursors of the paroxysm were recorded by strainmeter and tiltmeter stations. The volcano monitoring activity has been made by a joint team of researchers from the INGV sections of Catania, Napoli, Palermo and Rome, along with researchers from the Universities of Florence, Pisa, Roma Tre, and Palermo. The scientific activity was coordinated by a Synthesis Group made up by scientists responsible for the different monitoring techniques of INGV and Universities and by the volcanic experts of Commissione Nazionale Grandi Rischi of the Prime Minister Office (Civil Protection Department). The group made a daily evaluation of the state of the volcano and transmitted its recommendations to the Civil Protection Department (DPC). Several prevention measures were adopted by DPC, the main of which were the evacuation of the coast zone when strong acceleration of the Sciara del Fuoco slope motion (occurred twice) could led to a dangerous tsunami by flank collapse (as last occurred on 30 December 2002) and four days before the 15 March paroxysm when access was prohibited to the part of the volcano above 290 m asl.

Formation mechanism of electrical damage on sliding lubricated contacts for steel pair under DC electric field

A dynamic electrical pitting tester has been developed to investigate the effects of supply voltage, supply current, and oil film thickness on the electrical behavior, the normal and frictional forces, and the formation mechanism of electric damage for the sliding lubricated contacts of steel pair under DC electric field. Based on the experimental results for the normal and frictional forces, and the observations of the pitted surface, the process by which electrical damage occurs on the sliding lubricated surfaces is deduced. In this process, the molten metals are attracted to each other, leading to the formation of a molten metal column, which becomes a semisolid metal column due to the cooling action of the oil film. The normal force is significantly affected by this semisolid column, which grows and pushes against the lubricated contacts. Results also show that the frictional force primarily comes from the electrostriction force. The correlation formula for the damage width in terms of supply voltage, supply current, and oil film thickness is derived, but the supply current is the most important parameter affecting the width of the electric damage.

Transcriptional Repression by the T-box Proteins Tbx18 and Tbx15 Depends on Groucho Corepressors

Tbox18 (Tbx18) and Tbox15 (Tbx15) encode a closely related pair of vertebrate-specific T-box (Tbx) transcription factors. Functional analyses in the mouse have proven the requirement of Tbx15 in skin and skeletal development and of Tbx18 in the formation of the vertebral column, the ureter, and the posterior pole of the heart. Despite the accumulation of genetic data concerning the embryological roles of these genes, it is currently unclear how Tbx18 and Tbx15 exert their function on the molecular level. Here, we have initiated a molecular analysis of Tbx18 and Tbx15 proteins and have characterized functional domains for nuclear localization, DNA binding, and transcriptional modulation. We show that both proteins homo- and heterodimerize, bind to various combinations of T half-sites, and repress transcription in a Groucho-dependent manner. Competition with activating T-box proteins may constitute one mode of action as we show that Tbx18 interacts with Gata4 and Nkx2-5 and competes Tbx5-mediated activation of the cardiac Natriuretic peptide precursor type a-promoter and that ectopic expression of Tbx18 down-regulates Tbx6-activated Delta-like 1 expression in the somitic mesoderm in vivo.

Pyridine-containing versatile gelators for post-modification of gel tissues toward construction of novel porphyrin nanotubes

Low molecular weight gelators have recently been used as a template to construct novel kind of composite materials of different shape or structures such as helix, fibers, tape or tube through the electrostatic interaction between gelators and the intermediate molecules. In this article, we intricately apply the non-electrostatic interaction between gelator and fluorescent molecules to fabricate the gel fibers. To achieve our goal, we have intentionally designed pyridine containing cholesterol-based gelators 1– 3 by keeping one thing in our mind that during the formation of the stacking column the pyridine moieties will be arranged like a spiral staircase around the cholesterol column. The gelation properties of these three gelators are tested in different solvents including sublimable solvents like naphthalene and the gelator 1 has emerged as a ‘supergelator’. The morphologies strongly depend on the process of solvent removal from the gel state and the stabilities of gel have been tuned by the added metal ions like Ag(I) by using metal–ligand interaction. Lastly, we have decorated the gel fibers obtained from gelator 1 with fluorescent molecules like tetraphenyl porphyrin Zn(II) [ 4·H and 4·Zn] having photopolymerizable unit at the end of tether groups and the modified fibers are well characterized by UV–vis absorption spectroscopy, confocal laser scanning microscopy as well as transmission electron microscopy. This is a novel example of decoration of gel fibers with fluorescent molecules and the process will offer an alternate application in photochemical and electrochemical devices.

Linear arrays of ceramic microcavity plasma devices (127–180μm diameter) driven by buried coplanar electrodes: Shaping the intracavity electric field and emission profile

Shaping the electric field within a microcavity plasma device can be accomplished by the introduction of curvature into the dielectric-plasma interface when the microcavity is inserted between coplanar electrodes. To that end, linear arrays of cylindrical microcavity plasma devices with diameters of 127 or 180μm have been fabricated in low temperature cofired ceramic(εr=40) and operated in the rare gases at pressures in the 400–800Torr range. Comprising 72 microcavities, each linear array is powered by two buried Ag electrodes lying parallel to the array and driven by either a sinusoidal ac or bipolar pulsed dc waveform. Examination of Ne microplasmas with an optical telescope reveals the existence of pressure-dependent structure on the spatially resolved emission profiles. Strongest emission is observed from two negative glows on opposite sides of the microcavity. Confined to regions of low electric field strength and a weak gradient, the negative glows generate maximum intensity 25–35μm from the wall of a 180μm diameter microcavity. A central peak appears along the longitudinal axis of symmetry of the microcavity for pNe≳700Torr, reflecting the formation of a positive column. Operating voltages as low as 190V rms have been measured for excitation of a linear array of 180μm diameter devices operating at a Ne pressure of 400–700Torr and driven by a 20kHz voltage waveform.

Age estimation from the degree of osteophyte formation of vertebral columns in Japanese

To assess the age estimation from the degree of osteophyte formation of vertebral column, we set grading scores from 0 to 3 for the osteophyte formation based on the height of the process of vertebral column, and defined the average of the values at the cervical, thoracic and lumbar parts of the vertebra to be ‘osteophyte formation index’ for an individual. We evaluated osteophyte formation in autopsied 225 bodies (138 males, 87 females) during 5 years, and statistically analyzed the integrated data. The following were statistically obtained for each sex: correlation coefficient, regression equation, standard error of estimate (SE) between the score at each part of the vertebral column and age, and between ‘osteophyte formation index’ and age. In all the parts of the vertebra, there was a significant correlation between the score value and age. We recognized a significant correlation between ‘osteophyte formation index’ ( X) and age ( Y), and regression lines were Y=37.90+12.07 X (SE; 12.6 y.o.) in males and Y=36.67+18.64 X (SE; 11.9 y.o.) in females. It was apparent that to know the degree of the osteophyte formation was useful in age estimation.

Study of the dark phase in the initial stage of the positive column formation in a neon glow discharge

The initial stage of the positive column formation in a neon glow discharge is investigated both experimentally and theoretically. A decrease in the plasma radiation intensity (the so-called “dark phase”) was observed experimentally over a time period of about 1 ms. A similar dip was also observed in the time dependence of the electric field strength. The measured population of the lower metastable states of Ne was found to have a maximum at the beginning of the dark phase. A relevant theoretical model has been developed and used to perform calculations for the actual experimental conditions. A comparison between the numerical and experimental results shows that the model adequately describes the processes that occur during the formation of the positive column in a neon glow discharge. Experimental and theoretical studies show that the dark-phase effect is related to the excessive amount of metastable Ne atoms at the beginning of a discharge and, accordingly, to the high rates of stepwise ionization and chemionization.

Space discharge and gas lasers

The main processes in TE lasers are analyzed. Significant attention is given to models for the formation of a homogeneous plasma column and space charge. The reasons for channel growth at the stage of increasing voltage are demonstrated. A method to increase the energy input to the gas using a cathode with high emission properties is proposed. It is demonstrated that, in TEA CO2 lasers, the limiting deposited and radiated energy densities may amount to 1.35 and 0.085 J/cm3, respectively. Experimental results show that the duration of radiation can be increased using a variation in the composition and pressure of the active medium, the sectionalization of the active medium and the sequential excitation of the sections, and the excitation of the medium with a pulse train at a small (about 107 s) pulse duration and an interpulse interval of about 10−5 s.

Synthesis, Liquid‐Crystalline Properties, and Supramolecular Nanostructures of Dendronized Poly(isocyanide)s and Their Precursors

A series of novel dendronized pi-conjugated poly(isocyanide)s were synthesized successfully by using a Pd-Pt mu-ethynediyl dinuclear complex ([ClPt{P(C2H5)3}2C[triple bond]CPt{P(C2H5)3}2Cl]) as the initiator. The polymerizations of the dendronized monomers follow first-order kinetics, indicating that living polymerization takes place. The obtained polymers exhibit narrow polydispersities in the range of 1.03-1.20. Thermal properties of the poly(isocyanide)s as well as their isocyanide monomers and precursors with formamido (HCONH-) moieties as apexes were investigated by using differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). Both the peripheries and the apex groups of the dendrons affect the formation of supramolecular column and/or cubic phases of the precursors and monomers. The formamido precursor forms a liquid-crystalline phase due to intermolecular hydrogen bonding. The isocyanide monomer lacks this hydrogen-bonding ability and does not display an organized mesophase. All of the rigid poly(isocyanide)s with the monodendrons exhibit columnar liquid-crystalline phases. Interestingly, cylindrical structures of a poly(isocyanide) were directly visualized by using transmission electron microscopy (TEM).

Roles of Melting and Metasomatism in the Formation of the Lithospheric Mantle beneath the Leizhou Peninsula, South China

This study characterizes the nature of fluid interaction and melting processes in the lithospheric mantle beneath the Yingfengling and Tianyang volcanoes, Leizhou Peninsula, South China, using in situ trace-element analyses of clinopyroxene, amphibole and garnet from a suite of mantle-derived xenoliths. Clinopyroxenes from discrete spinel lherzolites exhibit large compositional variations ranging from extremely light rare earth element (LREE)-depleted to LREE-enriched. Trace-element modelling for depleted samples indicates that the Leizhou lherzolites are the residues of a mantle peridotite source after extraction of 1–11% melt generated by incremental melting in the spinel lherzolite field with the degree of melting increasing upwards from about 60 km to 30 km. This process is consistent with gradational melting at different depths in an upwelling asthenospheric column that subsequently cooled to form the current lithospheric mantle in this region. The calculated melt production rate of this column could generate mafic crust 5–6 km thick, which would account for most of the present-day lower crust. The formation of the lithospheric column is inferred to be related to Mesozoic lithosphere thinning. Al-augite pyroxenites occur in composite xenoliths; these are geochemically similar to HIMU-type ocean island basalt. These pyroxenites postdate the lithospheric column formation and belong to two episodes of magmatism. Early magmatism ( forming metapyroxenites) is inferred to have occurred during the opening of the South China Sea Basin (32–15 Ma), whereas the most recent magmatic episode (producing pyroxenites with igneous microstructures) occurred shortly before the eruption of the host magmas (6–0 3 Ma). Trace-element traverses from the contacts of the Al-augite pyroxenite with the spinel peridotite wall-rock in composite xenoliths record gradients in the strength and nature of metasomatic effects away from the contact, showing that equilibrium was not attained. Significant enrichment in highly incompatible elements close to the contacts, with only slight enrichment in Sr, LREE and Nb away from the contact, is inferred to reflect the different diffusion rates of specific trace elements. The observed geochemical gradients in metasomatic zones show that Sr, La, Ce and Nb have the highest diffusion rates, other REE are intermediate, and Zr, Hf and Ti have the lowest diffusion rates. Lower diffusion rates observed for Nb, Zr, Hf and Ti compared with REE may cause high field strength element (HFSE) negative anomalies in metasomatized peridotites. Therefore, metasomatized lherzolites with HFSE negative anomalies do not necessarily require a carbonatitic metasomatizing agent.

Perosomus elumbis em bovino: relato de caso

Objetivo: Descrever um caso de Perosomus elumbis, anomalia congênita raramente encontrada e de etiologia desconhecida. Descrição: Em um bezerro, macho, natimorto, Holandês, encaminhado para necropsia, constatou-se gênese anômala da coluna vertebral, caracterizada pela ausência das vértebras lombares, sacrais e coccígeas, bem como da medula espinhal a partir deste segmento. Apresentava, ainda, sete vértebras cervicais e seis torácicas, além de canal vertebral terminando em fundo cego. Mostrava, também, hipoplasia do coxal, artrogripose e atrofia da musculatura dos membros posteriores. Conclusões: As anomalias evidenciadas na necropsia comparadas aos dados da literatura permitiram o diagnóstico de Perosomus elumbis, uma anomalia congênita, rara, de etiologia desconhecida.

Biophysical Model of Intertidal Beach Crab Burrowing:Application and Significance

The biophysical principles and mechanisms involved in intertidal beach-crab burrowing have been studied. These answer some important and fundamental questions, such as how and what basic burrow patterns evolve in dynamic environmental conditions through a delicate balance struck between physical and biological (ethological) processes, and how does a burrow form faithfully record its environmental history in a sedimentary sequence? The study is primarily based on field and experimental data collected on the amphibious brachynuran crab family Ocypodidae (four species of Ocypodeand one species of Ilyoplax) from modern intertidal beach sectors on the Bay of Bengal coast, India. The model introduces a new concept of crab burrow cycle that includes three phases and involves three genetic categories of burrow forms—occupied, abandoned, and collapsed. The first phase (subaerial) begins with the excavation of simple (I or J types) occupied burrow populations and terminates with the development of plugged burrow apertures and sub-surface trapped air-column systems. Pressure equilibrium is reached between the burrow-base capillary water, air columns and sediment plugs. Formation of an air column is a mechanical means of supporting hollow burrow from collapse and creating an underwater quasi-terrestrial condition of living. The second phase (subaqueous) starts with tidal inundation and results in the final burrow architecture (Y, U, multibranched Y, and multiform U). The continued effects of external dynamic pressure fields on the plugs increases the internal air-column pressure causing pressure disequilibrium and lowering of capillary water levels unfavorable to the crabs for gill respiration. The burrower neutralizes the extra pressure to achieve previous pressure equilibrium and capillary water levels by excavating secondary branch(es) advantageously on the landward side of the main shaft and dumping the materials at the burrow-base. This mechanism, besides adding morphological complexities, ensures continued pressure equilibrium, the failure of which in any stage results in burrow collapse. The third phase (subaerial) creates a permanent pressure imbalance as the tidal water quickly recedes and protects the burrower inside as the air column bursts to set the crab free to start another burrow cycle afresh. The model has application potential in varied post-Jurassic coastal intertidal environmental settings occupied by quasiterrestrial crabs. It provides insight into various aspects of ichnology (taxonomy and recognition of ancient crab burrows; characterization and variability of the Psilonichnusichnofacies and intertidal ichnocoenoses; burrowing life habits of crabs and modalities of burrow preservation), environment (influence of bathymetry, tide and wave action, substrate properties, storm-induced episodic erosion and deposition on burrow architecture; environmental zonation of burrows; paleotidal range and marine transgression-regression events) and geomorphology (recognition of shoreline features). Being the first biophysical model of intertidal crab burrows, it contributes original data to the theoretical background of ichnology.

Topological whisker bundles of amphibole and frost column of quartz

Amphibole whiskers showing topological forms and frost column of quartz were found in association with hedenbergite crystals in a druse of skarn at Kakino mine, Gifu Prefecture, Japan. Both selectively grow from thin layers formed on the surfaces of Fe-rich portion of early formed hedenbergite crystals. Most whiskers occur in bundles of straight, helical, coil, curl, ribbon and rope forms. Single whiskers constituting these bundles are sub-micron size in thickness and millimeter to centimeter size in length, with aspect ratio attaining more than 1000, and are twisted. Micro-area XRD analyses indicate that the whiskers are crystalline, and not in amorphous state, in spite of their topological forms. Quartz layers showing fibrous texture, closely resembling frost column in form and texture, also occur in association with hedenbergite crystals and amphibole whiskers. Both amphibole whiskers and quartz frost columns nucleated and grew in layers formed on Fe-rich portions of hedenbergite, which was selectively reacted with S, H 2O and SiO 2 containing vapor phase. Based on these observations, the growth mechanism and the genesis of such unusual morphology are discussed. Essentially similar mechanism as vapor–liquid–solid (VLS) mechanism is suggested for amphibole whiskers. The same mechanism as for the formation of ice frost column is applicable to the formation of quartz frost column.