Effect of structure and phase content on wear resistance of the economical alloyed metastable and secondary hardening steels of Cr-Mn-Ti system

Despite a large number of studies in the field of assessing the causes of the formation of hot and cold cracks during surfacing of wear-resistant alloys, today the issues of working out the use of economically alloyed wear-resistant materials and the technique of their surfacing remain relevant. Goal: The purpose of this work is to study the effect of the structure and phase composition on the wear resistance of economically alloyed metastable and secondary hardening steels of the Cr-Mn-Ti system, as well as with additional alloying with Mo, B, V. Mechanized surfacing was carried out with flux cored wires AN-22 and AN-20 with the supply of a de-energized additive to the head of the weld pool, which reduces the content of sulfur and phosphorus, the specific consumption of electricity and increases the assimilation of alloying elements and the relative mass of the flux. Cladding by manual arc welding was carried out with coated electrodes with the addition of a depleted CaF2-coated flux-cored wire filler. When surfacing with a de-energized additive, the ratio of the filler to the main electrode, the relative mass was determined by β = m1 / m2 (m1, m2 are the mass of the filler and the electrode rod, respectively). Submerged arc surfacing was carried out in the following modes: IN = 300 ... 350 A, UD = 26 ... 30 V, q = 6 ... 10 kJ / cm, with manual surfacing - IN = 180 ... 220 A, UD = 25 ... Results: The studies carried out confirm the possibility of the formation of a “white band” both in alloys with a high concentration of austenitizing elements (Mn, C, Ni) and when alloying carbide-forming elements with a relatively low affinity for carbon (V, Mo). The indicators of resistance to cracking (КС, j-integral, δС), and, consequently, resistance to wear of secondary hardening steels are higher than those of metastable and tool steels.

Case Report: Phototherapeutic Keratectomy for Band Keratopathy Secondary to Chemo-Laser-Cryotherapy for Retinoblastoma

Purpose: To report the clinical outcomes of phototherapeutic keratectomy (PTK) for pediatric band keratopathy after treatment for retinoblastoma.Methods: A 5-year-old boy presented with a 2-year history of poor visual acuity and a horizontal gray-white band across the central cornea in the right eye. He was diagnosed with band keratopathy after chemo-laser-cryotherapy for retinoblastoma. The band keratopathy was treated via PTK using the Mel-90 excimer laser with an optical treatment zone of 7.0 mm and ablation depth of 120 μm. The patient was followed at 1 week and 3 months postoperatively.Results: Surgery and postoperative follow-up were uneventful. At the 3-month follow-up, the uncorrected distant visual acuity of the right eye improved to 20/125, and the corrected distance visual acuity improved to 20/70 with a refraction of +10.00 D/−2.50 DC × 15. The clarity of the ablated area was evidently improved. The central corneal thickness decreases from 612 to 584 μm. The optical coherence tomography showed the thin band of hyperreflectivity in the ablated area disappeared, corneal transparency improved and the corneal surface smoothened.Conclusions: PTK is a safe and effective procedure to treat band keratopathy following treatment of retinoblastoma in children. Early intervention can reduce the risk of developing deprivation amblyopia.

PREVALENSI DAN KELIMPAHAN PENYAKIT KARANG DI PERAIRAN DESA BUTON KABUPATEN MOROWALI SULAWESI TENGAH

Penyakit karang sekarang ini sudah menjadi perhatian utama para peneliti karang. Banyak kasus dilaporkan penyakit karang menjadi penyumbang terbesar kematian karang di sebuah perairan. Penelitian ini bertujuan untuk mengetahui prevalensi dan kelimpahan penyakit karang di Perairan Desa Buton, Kabupaten Morowali, Sulawesi Tengah. Metode pengambilan data prevalensi dan kelimpahan penyakit karang menggunkan belt transect (transek sabuk) dengan luas 180m2 yang ditarik sejajar garis pantai pada 3 (tiga) titik stasiun. Hasil penelitian menunjukan ditemukan sebanyak 5 (lima) jenis penyakit karang (White Band Disease, Brown Band Disease, Ulcerative White Spot, Bleaching, dan Black Band Disease dan 3 (tiga) jenis gangguan kesehatan karang (Fish bites, Crown-of-Thorn-Starfish (COTS), dan Tube formers). Secara umum total prevalensi penyakit karang di lokasi penelitian sebesar 78,7% (52,3% penyakit karang dan 26,4% berupa gangguan kesehatan karang) dengan kasus tertinggi terdapat di stasiun 1 (satu). lebih lanjut kelimpahan rata-rata penyakit karang sebesar 0,65 koloni/m2. Kelimpahan penyakit karang tertinggi ditemukan pada stasiun I yaitu sebesar 0,32 koloni/m2.Kata Kunci: Penyakit Karang, Prevalensi, Kelimpahan, Perairan Desa Buton

Chromatic Variation in Late Antique Rainbows

Depictions of rainbows in late antique and early Byzantine art follow the normal sequence of the spectral colours, only some bows exclude blue and violet. Another characteristic feature of the late antique rainbow is the inclusion of white and the non-spectral hue pink. In order to investigate chromatic characteristics, I use as case studies the comparatively few extant rainbow images of third- to sixth-century date from Thessaloniki, Constantinople, Rome and Ravenna. The rainbows, depicted in a floor mosaic, three illuminated manuscripts and three monumental wall mosaic decorations, are either part of narratives or rainbow-patterned borders used to frame other scenes. To throw light on the chromatic variations, ancient descriptions of rainbows are brought into the discussion and the representations are seen in relation to meteorological research. I propose that the late antique rainbow images follow two visual traditions, both of which can be traced back to the Hellenistic period and both of which are grounded in scientific research. One is the sunrise/sunset rainbow that ranges from red to green. I argue that the exclusion of blue/violet may be due to its being more difficult to see against the sky, the wavelength of violet being closest to the boundary beyond which coloured light tends to look black. The variant type, found especially in the church mosaics, covers the whole spectrum from red via green to violet as well as pink and white. I suggest that the non-spectral pink hues can be understood as the gradations of red that can sometimes be observed in the natural bow and that the white band provides highlight, which combined with a silver line indicates a strong luminance.

The megamouth shark, Megachasma pelagios, is not a luminous species

Despite its five meters length, the megamouth shark (Megachasma pelagios Taylor, Compagno & Struhsaker, 1983) is one of the rarest big sharks known in the world (117 specimens observed and documented so far). This filter-feeding shark has been assumed to be a luminous species, using its species-specific white band to produce bioluminescence as a lure trap. Another hypothesis was the use of the white band reflectivity to attract prey or for social recognition purposes. However, no histological study has ever been performed to confirm these assumptions so far. Two hypotheses about the megamouth shark's luminescence arose: firstly, the light emission may be intrinsically or extrinsically produced by specific light organs (photophores) located either on the upper jaw white band or inside the mouth; secondly, the luminous appearance might be a consequence of the reflection of prey luminescence on the white band during feeding events. Aims of the study were to test these hypotheses by highlighting the potential presence of specific photophores responsible for bioluminescence and to reveal and analyze the presence of specialized light-reflective structures in and around the mouth of the shark. By using different histological approaches (histological sections, fluorescent in situ hybridization, scanning electron microscopy) and spectrophotometry, this study allows to unravel these hypotheses and strongly supports that the megamouth shark does not emit bioluminescence, but might rather reflect the light produced by bioluminescent planktonic preys, thanks to the denticles of the white band.

LAJU INFEKSI PENYAKIT WHITE PLAGUE DAN WHITE BAND DISEASE DI PERAIRAN PULAU TIKUS, KOTA BENGKULU

Penyakit karang adalah gangguan terhadap kesehatan karang yang menyebabkan gangguan secara fisiologis bagi biota karang. Penyakit karang dapat memberikan dampak buruk terhadap proses pertumbuhan karang hingga dapat menyebabkan kematian karang disuatu perairan. Dampak dari penyakit karang terhadap ekosistem terumbu karang sangat besar, selain mengakibatkan kematian karang dalam skala yang luas, penyakit karang juga berdampak pada berkurangnya tingkat keanekaragaman sumberdaya alam. Penelitian ini bertujuan untuk mengetahui dan menganalisis laju infeksi penyakit White Plague dan White Band Disease di perairan Pulau Tikus, Kota Bengkulu. Penelitian ini dilaksanakan pada bulan September-Oktober 2019 di Perairan Pulau Tikus, Kota Bengkulu. Metode yang digunakan dalam penelitian ini adalah metode survei, pengamatan dan pengukuran langsung di Lapangan. Hasil Penelitian ini didapatkan bentuk pertumbuhan yang terinfeksi penyakit White Plague di Perairan Pulau Tikus Kota Bengkulu adalah bentuk pertumbuhan karang Massive dan penyakit White Band Disease pada karang Acropora. Metode yang digunakan dalam penelitian ini adalah metode survei, pengamatan dan pengukuran langsung di lapangan.Laju infeksi penyakit White Plague di perairan Pulau Tikus Kota Bengkulu adalah 0,009 - 0,023 cm/hari. Laju infeksi penyakit White Plague mengalami kenaikan setiap minggu dengan rata rata laju infeksi 0,015 cm/hari dan nilai laju infeksi penyakit White Band Disease yang terdapat pada karang Acropora di Perairan Pulau Tikus, Bengkulu yaitu 0,013 cm/hari – 0,030 cm/hari. Rata – rata yang diperoleh yaitu 0,024 cm/hari. Nilai laju infeksi karang menandakan bahwa sebagian besar kerusakan terumbu karang diakibatkan oleh penyakit karang.THE RATE OF WHITE PLAGUE AND WHITE BAND DISEASE IN TIKUS ISLAND, BENGKULU CITY. Coral disease is a disorder of coral health that causes physiological disruption to coral biota. The coral disease can adversely affect the coral growth process until it can lead to coral death in a waterway. The impact of coral disease on coral ecosystems is very large. In addition to resulting in coral death on a wide scale, a coral disease also affects natural resources' reduced diversity. This research aimed to determine and analyze the White Plague and White Band Disease's infection rate in Tikus Island, Bengkulu City. The research was conducted in September-October 2019, located in Tikus Island Water, Bengkulu City. The methods used in this study are direct survey, observation, and measurement methods in the Field. This study obtained a form of growth infected with White Plague disease in the Waters of Tikus Island Bengkulu City. The infection rate of White Plague Disease in Tikus Island was 0.009-0.023 cm/day. The quality of the condition of White Plague disease increased every week with an average infection rate of 0.015 cm/day, and the rate of infection rate of White Band Disease found in Acropora coral in the Waters of Tikus Island, Bengkulu which was 0.013 cm/day – 0.030 cm/day. The average obtained 0.024 cm/day. The coral infection rate indicates that most of the damage to coral reefs was caused by coral disease.

The Effect of Choline Alphoscerate on Non spatial memory and Neurogenesis in a Rat Model of Dual Stress

Choline alphoscerate (α-GPC) is a choline-based compound and acetylcholine precursor commonly found in the brain; it has been known to be effective in treating neuronal injury and increasing the levels of acetylcholine (Ach) and brain-derived neurotrophic factor (BDNF) which in turn enhances memory and cognitive function. This study was designed to establish rat models of dual stress using noise and restraint in order to investigate the effect of α-GPC on cognitive function and neurogenesis after dual stress. The rats were randomly divided into four groups as follows: a control group (CG), a control with α-GPC group (CDG), a noise-restraint stress group (NRSG), and a noise-restraint stress with α-GPC group (NRSDG). Two experimental groups were exposed to the double stress stimuli of noise and restraint, which involved 110dB sound pressure level (SPL) white band noise and restraint at the same time for 3 hours/day for 7 days. While the CG and NRSG received saline, the CDG and NRSDG received α-GPC (400mg/kg) orally after stress exposure. The α-GPC–treated group showed increased memory function compared to the dual stress group in the novel object recognition test. In analysis of the hippocampus, the α-GPC–treated group showed greater Choline acetyltransferase (ChAT) and BDNF expression compared to the dual stress group. The α-GPC–treated group showed significantly increased neuroblast expression compared to the dual stress group, which suggests that α-GPC enhances BDNF expression and protects the activity of the immature cells at the dentate gyrus. Our results suggest that α-GPC treatment can protect cognitive function and neurogenesis in a dual stress model.

PREVALENSI DAN JENIS PENYAKIT YANG MENGINFEKSI KARANG DI PERAIRAN PULAU ENGGANO BENGKULU

Penyakit karang merupakan salah satu permasalahan ekosistem terumbu karang yang diakibatkan oleh manusia. Penyakit karang dapat menyebabkan penurunan kualitas dan daya imun karang yang ditandai dengan terhambatnya laju pertumbuhan pada karang dan berdampak pada matinya karang di suatu perairan. Penelitian ini bertujuan untuk mengidentifikasi jenis penyakit dan bentuk pertumbuhan karang yang sering terinfeksi penyakit serta menganalisis prevalensi penyakit karang di Perairan Pulau Enggano, Bengkulu. Penelitian ini menggunakan metode survei. Pengambilan data penyakit karang dengan metode transek sabuk (Belt Transect). Hasil penelitian didapatkn 9 jenis penyakit yang ditemukan di Pulau Enggano, yaitu Yellow Band Desease, Black Band Desease, White Band Desease, Red Band Desease, Dark Plague, White Plague, Pink Plotch, dan Ulcerative White Spots, serta White Spot. Sedangkan bentuk pertumbuhan (lifeform) karang yang terinfeksi adalah Coral Massive dan Acropora Branching. Tingkat prevelensi karang tertinggi terdapat pada lokasi Kahabi, sedangkan terendah pada Pulau Dua di bagian windward. Tingginya tingkat prevalensi di Kahabi dimungkinkan karena tingginya kedalaman di lokasi tersebut. Rendahnya tingkat prevalensi karang pada Pulau Dua di sisi windward dimungkinkan karena pada sisi ini merupakan daerah yang terkena arus tiap saat, sehingga membantu karang dalam membersihkan sedimen yang menempel pada permukaan yang dimungkinkan membawa bakteri penyebab penyakit karang.CORAL DISEASE PREVALENCE IN ENGGANO ISLAND, BENGKULU. Coral disease is one of the coral reef ecosystem problems caused by humans. Coral disease causes a decrease in the quality and immunity of corals characterized by stunted growth rates on corals and impacts on the death of corals in waters. This study aims to identify the types of coral disease and coral lifeform that are often infected and analyze the prevalence of coral disease in Enggano Island Waters, Bengkulu. This research used survey method. Coral disease data were obtained using the belt transect method. The results obtained 9 types of coral diseases found on Enggano Island, namely Yellow Band Desease, Black Band Desease, White Band Desease, Red Band Desease, Dark Plague, White Plague, Pink Plotch, and Ulcerative White Spots, and White Spot. While infected lifeforms were Coral Massive and Acropora Branching. The highest level of coral prevalence was at the Kahabi site, while the lowest was on Pulau Dua in the windward area. The high prevalence rate in Kahabi might be due to the high depth at the location. The low level of coral prevalence on Pulau Dua on the windward side might be caused by being exposed to the current at any time, thus helping the coral in cleaning sediments attached to the surface which could carry the bacteria that cause coral disease.

A new species of Cyrtodactylus (Squamata, Gekkonidae) from Cambodia’s Prey Lang Wildlife Sanctuary

Cyrtodactylus phnomchiensissp. nov. is described from Phnom Chi, an isolated mountain in Prey Lang Wildlife Sanctuary, Kampong Thom Province, Cambodia. The new species is recognized by having a unique combination of morphological characters, including snout-vent length 76.1–80.7 mm; paravertebral tubercles 31–36; ventral scales 45–54; enlarged femoral scales 0–8, without pores; enlarged precloacal scales 7–10, bearing pores 4–5 in males, pits 1–7 in females; the posterior border of nuchal loop unbroken and pointed, bordered anteriorly and posteriorly by a broad yellow or yellowish white band; and yellow spots on top of head. The new species also represents a divergent mitochondrial DNA lineage within the C. irregularis complex that is closely related to C. ziegleri, but the phylogenetic relationships among the new species and two divergent mitochondrial subclades within C. ziegleri are not resolved based on available sequence data. Cyrtodactylus phnomchiensissp. nov. is the only member of the C. irregularis complex known to occur west of the Mekong River. The new species may be endemic to Phnom Chi, and likely faces imminent conservation threats.