Peel Techniques Research Articles

(Invited) Particles Removal on Challenging Surfaces

In semiconductor manufacturing, particle removal is critical for high yield. This study investigates cleaning efficiency on challenging surfaces like deep trenches, wafer bevel, and bonded dies, using various methods. Intentional contamination was applied using silica, silicon nitride, and ceria particles. Cleaning methods tested include high-velocity biphasic sprays, cryogenic processes, and polymer peel techniques. Results show that while polymer peeling offers excellent particle removal efficiency (PRE) on blanket surfaces and wafer bevels, it struggles with high aspect ratio features due to polymer film dewetting. The study provides a new methodology for generating cleaning tool fingerprints and highlights the importance of key contamination parameters, such as particle nature, media characteristics, and queue time. The findings underscore the need for evolving cleaning processes to address the complexities of modern semiconductor surfaces.

Surgical classification for large macular hole: based on different surgical techniques results: the CLOSE study group

BackgroundThe CLOSE study group proposes an updated surgical classification for large macular holes based on a systematic review of new treatments. Recently, many new techniques have been introduced to treat large full-thickness macular holes (FTMH); although the indications are not clear. An updated surgical classification is needed to help surgical decision-making.MethodsWe gathered published series by the CLOSE Study Group members and from literature search until June 2021. Techniques included: internal limiting membrane peeling (ILM peeling), ILM flaps, macular hydrodissection (macular hydro), human amniotic membrane graft (hAM), and autologous retinal transplantation (ART). Within each technique, chi-square test assessed association between the minimal linear diameter (MLD) (in µm) and closure rate; the postoperative best-corrected visual acuity (BCVA) gains were compared among groups.ResultsData extraction included 31 published articles: total of 1135 eyes. Eyes were divided into the following groups: ILM peel (n: 683), ILM Flap (n: 233), macular hydrodissection (n: 64), hAM (n: 59), and ART (n: 96). The initial BCVA and size were heterogenous between the groups. ILM peel showed the best results in large FTMH ≤ 535 µm (closure rate 96.8%); adjusted mean BCVA: 0.49 (LogMAR) with a statistical difference among groups. Large FTMH between 535 and 799 µm: ILM flap technique showed better results (closure rate 99.0%); adjusted mean BCVA: 0.67(LogMAR); also with a statistical difference. For large FTMH ≥ 800 µm more invasive techniques are required. Use of hAM, macular hydrodissection and ART showed higher closure rates for this category (100%, 83.3% and 90.5% respectively), and adjusted mean BCVA varied from 0.76 to 0.89. Although there was no statistical difference between those techniques for this group due to the smaller number of cases.ConclusionsThe CLOSE study group demonstrated the potential usefulness of a new surgical classification for large FTMHs and propose OCT biomarkers for use in clinical practice and future research. This new classification demonstrated that Large (400–550 µm) and X-Large (550–800 µm) holes can be treated highly successfully with ILM peel and ILM flap techniques, respectively. Further studies are necessary for the larger FTMHs (XX-Large and Giant), using the CLOSE classification, in order to determine which technique is better suited for each hole size and characteristics.

Functional internal rotation is similar between lesser tuberosity osteotomy and subscapularis peel in total shoulder arthroplasty: short-term follow-up.

Lesser tuberosity osteotomy (LTO) and subscapularis peel (Peel) are 2 common techniques used to mobilize the subscapularis tendon during anatomic total shoulder arthroplasty (TSA). The literature is inconclusive over which technique is optimal; thus, controversy exists over which technique should be performed. The purpose of this study was to compare specific functional internal rotation tasks and general outcome scores in TSA patients who received either an LTO or Peel. A retrospective review of 563 patients treated with primary TSA using either an LTO (n=358) or Peel (n=205) with a minimum 2-year follow-up was performed. Subjective internal rotation, active internal rotation, and specific questions related to functional internal rotation isolated from the Simple Shoulder Test (SST) and American Shoulder and Elbow Surgeons functional questionnaires were reviewed. Other outcome scores including visual analog scale pain and function, Single Assessment Numerical Evaluation, SST, American Shoulder and Elbow Surgeons, and revision rates were compared between the 2 groups. The study found no difference in postoperative functional internal rotation and range of motion between LTO and Peel. Patients who received a Peel were shown to have a slightly greater improvement in the ability to perform toileting and a higher average change in SST score that did not reach clinical significance. There was no difference in the percentage of maximal improvement, revision rate, or need for revision between the 2 groups. No difference was found between the LTO and Peel techniques in regard to functional tasks of internal rotation at short-term follow-up.

A permineralized Early Cretaceous lycopsid from China and the evolution of crown clubmosses.

Lycopodiaceae are one of three surviving families of lycopsids, a lineage of vascular plants with a fossil history dating to at least the Early Devonian or perhaps the Late Silurian (c. 415Ma). Many fossils have been linked to crown Lycopodiaceae, but the lack of well-preserved material has hindered definitive recognition of this group in the paleobotanical record. New, exceptionally well-preserved permineralized lycopsid fossils from the Early Cretaceous (125.6±1.0Ma) of Inner Mongolia, China, were examined in detail using acetate peel and micro-computed tomography techniques. The anatomy of extant Lycopodiaceae was analyzed for comparison using fluorescence microscopy. Phylogenetic relationships of the new fossil to extant Lycopodiaceae were evaluated using parsimony and maximum likelihood analyses. Lycopodicaulis oellgaardii gen. et sp. nov. provides the earliest unequivocal and best-documented evidence of crown Lycopodiaceae and Lycopodioideae, based on anatomically-preserved fossil material. Recognition of Lycopodicaulis in Asia during the Early Cretaceous indicates the presence of crown Lycopodiaceae at this time, and striking similarities of stem anatomy with extant species provide a framework for the understanding of the interaction of branching and vascular anatomy in crown-group lycopsids.

Single-Layer Inverted Internal Limiting Membrane Flap Versus Conventional Peel for Small- or Medium-Sized Full-Thickness Macular Holes

To analyze the outcomes of using an internal limiting membrane (ILM) flap and the conventional ILM peel technique for small- or medium-sized full-thickness macular hole (FTMH) repair. Retrospective, interventional case series. Eyes with an FTMH ≤400 µm that underwent vitrectomy with a single-layer inverted ILM flap (flap group, 55 eyes) or an ILM peel (peel group, 62 eyes) were enrolled. Best-corrected visual acuity (BCVA) and optical coherence tomography (OCT) measurements were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. Primary hole closure was achieved in 54 (98%) and 60 (97%) eyes in the flap and peel groups, respectively. The preoperative and postoperative 12-month BCVA values were comparable between the groups but were significantly better in the flap than in the peel group at 1 month (mean ± SD logMAR: 0.83 ± 0.43 vs 1.14 ± 0.50; P=.001), 3 months (0.58 ± 0.33 vs 0.82 ± 0.43; P=.002), and 6 months (0.56 ± 0.32 vs. 0.72 ± 0.48; P=.028). In the flap group, foveal gliosis was less common than in the peel group at 1 month (P=.030), and restored external limiting membrane and interdigitation zone was more common at 3 months (P=.046 and P < .001, respectively). The single-layer ILM flap and conventional ILM peel techniques both closed FTMHs and improved vision. ILM flaps were associated with better visual outcomes up to 6 months postoperatively and should be considered in FTMHs ≤400 µm.

Weltrichia magna sp. nov., a new record for the Middle Jurassic of Oaxaca, México

The Jurassic locality San Juan Mixtepec (Zorrillo Formation in the state of Oaxaca) contains fossil plants of the order Bennettitales, mainly of the genus Zamites, as well as reproductive structures of the genera Williamsonia, Williamsoniella and Weltrichia, but male reproductive structures of the latter genus are scarce and almost restricted to the south of Mexico; they have also been reported in the Triassic of the north of Mexico. Here we report a new record for this locality and a new species of male reproductive structure of the genus Weltrichia. We recovered half of an adpression in fine-grained sandstone with the positive and negative of the adaxial part of the male reproductive structure, which when open measures 22.6 cm in diameter. A reconstruction suggests the presence of ten centrifugal rays that become thinner towards the acute apex and are fused in a central basal cup. The structure exhibits complete centrifugal rays with basal structures that are interpreted as insertion sites for pollen sacs. We employed acetate peel, mechanical separation and hydrofluoric acid (HF) maceration techniques for extraction of anatomical samples. We compared 13 morphological and 10 anatomical characters with previous records from localities in México, Europe, Asia and other parts of the world. We observed epidermal cells and syndetocheilic stomatal apparatuses, which corroborate an epidermal affinity to the Bennettitales. This new record would be the largest male reproductive structure found in the region thus far, and increases the distribution of Weltrichia in the Jurassic of Oaxaca.

The Lesser Tuberosity Osteotomy Exposure for Total Shoulder Arthroplasty.

The lesser tuberosity osteotomy (LTO) is a commonly employed technique for mobilizing the subscapularis tendon during anatomic total shoulder arthroplasty that is performed through a deltopectoral approach. During this procedure, the lesser tuberosity is osteotomized from the proximal aspect of the humerus while maintaining the strong tendon-to-bone attachment of the subscapularis tendon insertion. After the shoulder arthroplasty is performed, the lesser tuberosity osseous fragment is then resecured to the proximal aspect of the humerus with heavy nonabsorbable suture, which allows for direct bone-to-bone compression and healing of the fragment to the proximal aspect of the humerus. This technique may be utilized for subscapularis tendon mobilization in any primary and some revision anatomic total shoulder arthroplasty procedures. The procedure is performed as follows. (1) Preoperative planning is performed. (2) The patient is positioned in the semi-upright beach-chair position, and the shoulder girdle and the upper arm are prepared and draped. (3) A standard deltopectoral approach is utilized. (4) A tenotomy of the long head of the biceps tendon is performed, exposing the bicipital groove. (5) An LTO is made from lateral to medial with an oscillating saw and is completed with use of an osteotome. (6) The remaining inferior portion of the subscapularis and capsule are released off of the humerus. (7) The total shoulder arthroplasty is completed up to the point of implantation of the final humeral component. (8) Four drill-holes are made lateral to the bicipital groove and osteotomy site. (9) Heavy nonabsorbable sutures, with or without cerclage wires, are passed from lateral to medial around the humeral stem and passed medial to the osteotomy fragment through the insertion of the subscapularis tendon. (10) The sutures are then tensioned and tied with the arm in 30° of external rotation. (11) The wound is irrigated, dried, and closed in layered fashion. The most commonly accepted alternative approaches include the subscapularis tenotomy and subscapularis peel techniques. The LTO approach technique was developed to take advantage of bone-to-bone healing and to address concerns regarding poor tendon-to-tendon or tendon-to-bone healing in the subscapularis tenotomy and subscapularis peel exposure techniques, respectively. Based on numerous published studies, excellent clinical results are achieved with anatomic total shoulder arthroplasty. When comparing surgical techniques involving the subscapularis in Level-I, randomized controlled trials, no significant differences exist among clinical outcomes, range of motion, or strength between the different techniques. Three-dimensional preoperative templating software allows for the anticipation of potential operative challenges, the prediction of implant limitations, and more accurate assessment of abnormal glenoid morphology and wear patterns.An articulating arm positioner can be helpful in controlling the arm position without the need for an extra surgical assistant.The goal thickness of the LTO is 10 mm. If the osteotomy is made too thin, there is a risk that the repair sutures cut through the lesser tuberosity fragment, leading to subscapularis repair failure.Releasing the capsule from the subscapularis is a critical step to ensure adequate tendon excursion for later repair and restoration of external rotation in arthritic shoulders. However, careful attention must be directed to the position and orientation of the axillary nerve in order to avoid iatrogenic injury during this critical step.Creating the drill-holes lateral to the bicipital groove takes advantage of the very strong and dense bone in that area of the proximal aspect of the humerus, enhancing the integrity of the repair.The tension band suture is critical to aid in further compression of the LTO fragment when the arm is brought into external rotation.Closing the rotator interval substantially increases the strength of the subscapularis repair; however, the closure of the interval must be made with the arm in at least 30° of external rotation in order to avoid iatrogenic motion restriction.Using interrupted nonabsorbable sutures to close the deltopectoral interval at the conclusion of the procedure is helpful in the event that any revision procedure is needed because these sutures will guide the revision surgeon toward making the deltopectoral approach in the correct interval. LTO = lesser tuberosity osteotomyROM = range of motionASES = American Shoulder and Elbow SurgeonsWOOS = Western Ontario Osteoarthritis of the Shoulder indexVAS = visual analog scaleSF-36 = 36-Item Short Form Health SurveySST = Simple Shoulder TestDVT = deep-vein thrombosis.

Systematic review and network meta-analysis of subscapularis management techniques in anatomic total shoulder arthroplasty

Controversy exists regarding the optimal subscapularis management technique in patients undergoing anatomic total shoulder arthroplasty. The purpose of this study was to compare clinical, radiographic, and functional outcomes between subscapularis tenotomy (ST), lesser tuberosity osteotomy (LTO), and subscapularis peel (SP) techniques. We performed a level III systematic review and network meta-analysis comparing ST, LTO, and SP in patients undergoing anatomic total shoulder arthroplasty. Our primary collection endpoints included range of motion, subscapularis function, subscapularis healing, functional patient-reported outcomes, complications, and revision surgery. Data were pooled and network meta-analysis was performed owing to the comparison of 3 groups. Eight studies met our inclusion criteria for meta-analysis. There was no difference in sex or primary diagnosis between the 3 cohorts. No significant difference was found in postoperative external rotation or forward flexion between the groups. Meta-analysis found the SP cohort to have significantly greater internal rotation strength than the ST cohort. The belly-press test results were negative most commonly in the LTO group, and there was a significant difference compared with the ST or SP group (P < .0001). The weighted-mean healing rate for the LTO site was 98.9% on radiographic imaging. There was a significantly higher ultrasound healing rate in the LTO cohort than in the ST and SP cohorts. All groups had good postoperative patient-reported outcome scores (average American Shoulder and Elbow Surgeons score range, 78.6-87) and a relatively low rate of complications (3%). This network meta-analysis demonstrates that the LTO group has superior healing and postoperative subscapularis-specific physical examination test results compared with the ST and SP groups. However, no difference in postoperative range of motion was found between the groups, and all techniques demonstrated good functional patient-reported outcomes, with a low rate of postoperative complications. These findings provide evidence-based support that ST, SP, and LTO all demonstrate similar outcomes; therefore, selection should be based on surgeon experience and comfort.

Age and Growth of Striped Venus Clam Chamelea gallina (Linnaeus, 1758) in the Mid-Western Adriatic Sea: A Comparison of Three Laboratory Techniques

Age and growth studies provide critical data for clam fishery management. Three ageing techniques, thin sections and acetate peel replicas – which involve shell sectioning – and surface growth rings were used to estimate the age and growth of Chamelea gallina populations in the mid-western Adriatic Sea. Their results were compared to identify the most reliable and least time-consuming approach. There were no significant differences between the two shell sectioning techniques (χ2 = 4.66, df = 3, p = 0.198), which were described by the same von Bertalanffy (VBF) growth curve parameters (L∞ = 43.9, k = 0.26, t0 = -0.84), whereas significantly different L∞ and k values were found between the two shell sectioning techniques and surface growth rings (L∞: χ2 = 13.62, df = 1, p < 0.001; k: χ2 = 9.18, df = 1, p < 0.002; these statistics refer to the comparison between acetate peels and surface growth rings).The latter approach proved unreliable and error-prone, as it underestimated age and overestimated the growth rate (L∞ = 26.4, k = 1.91, t0 = - 0.11). Although the thin sections and acetate peel techniques both provide reliable age and growth estimates, the former approach was less time-consuming. Our analyses demonstrated that shell growth is slower in the cold season and in older specimens and that it has slowed down over the past few decades.

Outcomes of lesser tuberosity osteotomy in revision anatomic shoulder arthroplasty

Lesser tuberosity osteotomy (LTO) is a common surgical approach during anatomic shoulder arthroplasty. Outcomes of LTO have been shown to be similar to subscapularis tenotomy and peel techniques, but little is known about the outcomes of LTO during revision arthroplasty. This retrospective case series included 10 consecutive patients who underwent LTO during revision shoulder arthroplasty at a single institution from 2012 to 2016. Patients underwent a preoperative computed tomography scan to evaluate the lesser tuberosity bone stock. Demographic information, radiographic evidence of LTO healing, outcomes of range of motion, subscapularis strength, and visual analog scale pain scores were analyzed. Revision total shoulder arthroplasty with LTO was performed for glenoid arthritis after hemiarthroplasty in 10 patients. Average age at surgery was 59.8 years, and no humeral stems were revised. Eight of 10 patients had prior subscapularis tenotomy. Average follow-up after revision surgery was 9.2 months. LTO union was documented in 80% and nondisplaced nonunion in 20%. At follow-up, 50% reported mild pain. Subscapularis strength testing was graded normal in 80% and weak in 20%. Average visual analog scale pain improved from 9.4 prerevision to 4.8 postrevision (P < .05). On average, range of motion improved in active forward elevation from 123° to 141° and remained unchanged in active external rotation from 42° to 42°. Patients undergoing LTO during revision anatomic shoulder arthroplasty demonstrate successful LTO bony healing, improvement in pain, and improved forward elevation. In select patients not requiring humeral stem revision, LTO is a safe and effective surgical approach to subscapularis management during revision anatomic shoulder arthroplasty.

Under pressure? Epicormic shoots and traumatic growth zones in high-latitude Triassic trees from East Antarctica.

Investigating the biology of trees that were growing at high latitudes during warmer geological periods is key to understanding the functioning of both past and future forest ecosystems. The aim of this study is to report the first co-occurrence of epicormic shoots and traumatic growth zones in fossil trees from the Triassic of Antarctica and to discuss their biological and environmental implications. Permineralized woods bearing scars of epicormic shoots were collected from the Triassic Fremouw Formation in Gordon Valley, Central Transantarctic Mountains, Antarctica in 2010. Samples from different portions of three specimens were prepared using standard thin section and hydrofluoric (HF) acid peel techniques, and anatomical details were studied in transmitted light. The fossil woods represent the outer part of trunks, with at least 40 growth rings that are 0.2-4.8 mm in width. Anatomical comparisons suggest that they represent a new tree taxon for the Triassic of Antarctica. Numerous small epicormic shoots can be seen crossing the wood almost horizontally and are locally branched. Each specimen also contains several occurrences of traumatic growth zones located in the early wood, in the cells produced either at the very start of the growing season or slightly later. This is the first report of epicormic shoots and traumatic growth zones in the wood of a Triassic tree from Antarctica. Their co-occurrence indicates that these trees from Gordon Valley were subjected to environmental stresses not seen in Triassic trees previously described from this region. This suggests that they had a different biology and/or were growing in a different habitat, which offers a new glimpse into the diversity of high-latitude trees in the Triassic greenhouse climate.

Chemical Peels: Indications and Special Considerations for the Male Patient.

Chemical peels are a mainstay of aesthetic medicine and an increasingly popular cosmetic procedure performed in men. To review the indications for chemical peels with an emphasis on performing this procedure in male patients. Review of the English PubMed/MEDLINE literature and specialty texts in cosmetic dermatology, oculoplastic, and facial aesthetic surgery regarding sex-specific use of chemical peels in men. Conditions treated successfully with chemical peels in men include acne vulgaris, acne scarring, rosacea, keratosis pilaris, melasma, actinic keratosis, photodamage, resurfacing of surgical reconstruction scars, and periorbital rejuvenation. Chemical peels are commonly combined with other nonsurgical cosmetic procedures to optimize results. Male patients may require a greater number of treatments or higher concentration of peeling agent due to increased sebaceous quality of skin and hair follicle density. Chemical peels are a cost-effective and reliable treatment for a variety of aesthetic and medical skin conditions. Given the increasing demand for noninvasive cosmetic procedures among men, dermatologists should have an understanding of chemical peel applications and techniques to address the concerns of male patients.

Dordrechtites arcanus sp. nov., an Anatomically Preserved Gymnospermous Reproductive Structure from the Middle Triassic of Antarctica

The genus Dordrechtites is an isolated ovulate structure previously described only from South Africa and Australia as impressions. The discovery of compressed and permineralized specimens of this taxon at the base of Mount Falla (uppermost Fremouw Formation) in the central Transantarctic Mountains extends the geographical and geological distribution of the genus and increases the known floral diversity of the Triassic of Antarctica. The first permineralized species, Dordrechtites arcanus, is described using standard acetate peel techniques and includes internal anatomy of an elongate arm that extends over the top of a central cupule containing two elongate, bilaterally symmetrical, orthotropous ovules. An arc-shaped collateral vascular bundle extends from the arm into the top of the cupule, branches, and then extends around the ovule to about halfway down to the micropylar end. The cupule is parenchymatous and includes transfusion tissue with cells that have pitted walls. The sclerotesta of the ovule is up to 200 μm thick, consisting of an outer layer with longitudinally oriented, thick-walled cells and an inner layer one cell thick of rectangular, thick-walled cells. The micropyle is flared at the attenuated tip of the pyramidal cupule. The four previously described species of Dordrechtites have uncertain affinities, and although the morphology and anatomy of this taxon is now known, the affinities within the gymnosperms are still uncertain.

Reproductive and vegetative organs with affinities to Haloragaceae from the Upper Cretaceous Huepac Chert Locality of Sonora, Mexico

From the Upper Cretaceous (Maastrichtian-Campanian) Huepac Chert Locality of the Tarahumara Formation, a new extinct aquatic plant of the Haloragaceae (Subclass: Rosidae), Tarahumara sophiae Hernández-Castillo and Cevallos-Ferriz, is presented. It is reconstructed on the basis of both reproductive and vegetative organs preserved in chert. Its description and comparison with extant plants are based on the analysis of 350 permanent slides made with thin section and peel techniques. A mosaic of anatomical and morphological characters found in the extant Myriophyllum, Meziella, and Haloragodendron is used to characterize the new taxon. The development from flower to fruit in the fossil plant follows similar stages found in some extant species of Myriophyllum. However, a floral cup is reported for the first time in the family, and it is compared to the persistent fused sepals (terminal corona) of Meziella. This plant reconstruction increases the morphological diversity of the Haloragaceae, demonstrates the presence of a new dispersal mechanism compared with those known for the family, suggests that this lineage had originated by at least the Upper Cretaceous, and refutes the interpretation of several haloragacean Tertiary reports as representing genera of extant plants.

Influence of creep phenomenon and surface roughness on the adhesion of Xenopus laevis eggs to different substrates

The adhesion of fertilized and nonfertilized Xenopus laevis eggs to various surfaces differing in texture, roughness, and chemical composition was examined. Techniques regularly used in the fields of coating and adhesives were adopted. The stresses for the disconnection of eggs from different surfaces were evaluated by a custom-made apparatus, which disconnects the eggs by applying a regulated water pressure. The strength of adhesion depends, among others, on the roughness of the surfaces. A commercial roughness tester evaluated this parameter. It was observed that the rougher the surface, the better the adhesion between the egg and the surface. Maximal adhesion between the eggs and rough surfaces was detected 1 h after the first contact. For smooth surfaces (hydrogels), such a maximum was recognized only after 24 h had elapsed. In addition to the character of the surfaces, the creep of the jelly coat with time significantly influenced the strength of adhesion. The creep of the jelly coat was also dependent on the degree of swelling. The swelling of an egg's jelly coat during the first 8.5 h of the process was monitored by weight. Major changes in weight were observed during the first 100 min. After longer periods, the weight reached an asymptotic level. Incorporating polyvinyl pyrrolidone (PVP) into the medium eliminates the adhesion and stickiness of Xenopus eggs in the laboratory. Tensile bond stress and peel techniques were used to estimate the egg's adhesion to several surfaces. These tests revealed that the first contact between the egg and substrate resulted in a stronger adhesion than when the egg was disconnected and re-glued (re-adhered) to the same surface. Adhesion to natural surfaces (pebbles and Nimephea leaves) was better than to synthetic smooth surfaces. The shorter the distance between the female toad and any surface, the better the adhesion of the eggs.

Stomatal responses to light in the facultative Crassulacean acid metabolism species, Portulacaria afra

Guard cell responses to light are mediated by guard cell chlorophyll and by a specific blue light photoreceptor. Gas exchange and epidermal peel techniques were employed to investigate these responses in the facultative Crassulacean acid metabolism (CAM) species, Portulacaria afra (L.) Jacq. In P. afra individuals performing C3 metabolism, red light stimulated an increase in leaf conductance in intact leaves and stomatal opening in isolated epidermal peels, indicating the presence in guard cells of the chlorophyll‐mediated response to light. Under a background of continuous red illumination, conductance exhibited transient increases following pulses of blue but not red light, indicating that the specific stomatal response to blue light was also operative. In contrast, in CAM individuals, conductance in gas exchange experiments and stomatal opening in epidermal peel experiments were not stimulated by red light. In CAM plants, conductance did not increase following blue light pulses administered over a range of temperatures, vapor pressure differences (VPD), ambient CO2 concentrations and background red light intensities. These results indicate that P. afra does possess typical guard cell responses to light when performing C3 metabolism. The metabolic pathways mediating these responses are either lost or inhibited when CAM is induced.

Estimation of Heavy Atom Content and Distribution in Chlorite Using Corrected X-Ray Powder Diffraction Intensities

AbstractThe heavy atom content and distribution in chlorite were estimated using the relative intensities of basal X-ray powder diffraction (XRD) peaks. For these peaks to be meaningful, however, corrections had to be made for the effects of sample thickness, sample length, and preferred orientation of the mineral grains, all of which are 2θ dependent. The effects of sample thickness were corrected for by a simple formula. The effects of sample length were accounted for by using rectangular samples and by ensuring that the sample intersected the X-ray beam through the range of diffraction angles of interest. Preferred orientation of mineral grains were either measured directly or estimated. Estimated values were quicker and easier to obtain and were within 5% of measured values. A comparison of the compositional parameters of chlorite estimated before correcting for these sample effects with those estimated after the corrections had been applied indicate that the uncorrected values differed from the corrected values by as much as 55% of the latter values. Mounts of a single sample prepared by different filter-membrane peel and porous-plate techniques yielded widely different compositions until the measurements were corrected for sample effects. Analyses in triplicate indicated that the XRD intensity ratio 003/001 is preferred for calculating heavy atom distributions and abundances in chlorite because of the relative strength of the 001 peak.

Inversion technique for IR heterodyne sounding of stratospheric constituents from space platforms

The techniques which have been employed for inversion of IR heterodyne measurements for remote sounding of stratospheric trace constituents usually rely on either geometric effects based on limb-scan observations (i.e., onion peel techniques) or spectral effects by using weighting functions corresponding to different frequencies of an IR spectral line. An experimental approach and inversion technique are discussed which optimize the retrieval of concentration profiles by combining the geometric and the spectral effects in an IR heterodyne receiver. The results of inversions of some synthetic ClO spectral lines corresponding to solar occultation limb scans of the stratosphere are presented, indicating considerable improvement in the accuracy of the retrieved profiles. The effects of noise on the accuracy of retrievals are discussed for realistic situations.

Acetate Peel Techniques Applied to Cherts

ABSTRACT The successful application of acetate peel techniques to cherts is reported along with a combined etching and staining procedure for cherts replacing carbonates.

Acetate Peel and Other Biotic Data from Selected Antarctic Permian Beds

Introduction Published data on fossil biotic elements from the Antarctic Paleotoic, particularly the Permian, are most sparse. Additions of any kind, for example, reports on spoor, fragmentary fossils artifacts among others, can help to expand available knowledge. The present study a spin-of3 of a larger research project, supplements previous reports on the same theme (Tasch, 1968a. 19685). Collections during austral summer 1966-67 included samples from fossiliferous and ncyn-fossiliferous l)eds. Of these, samples studied by the acetate peel technique incIuded in this report came from the following localities and beds: Ohio Range beds 0-17, 0^19 (for details see Tasch and Gaffordn 1968; Tasch, 1970); Sentinel Mts.-bed S-14 Whiteout Nunatak near the contact of the Polarstar Formation and the Whiteout Conglomerate. Standard acetate peel techniques were used (Stewart and Taylor, 1965) . In addition to acetate peel stlldies, an object attached to a leaiid conchostracan valve from the Ohio Range Levia Zone (Bed 0-21.8), not previously reported in the literature is figured and described.