NEW RESULTS OF INTEGRATED LITHOFACIES AND BIOSTRATIGRAPHICAL STUDY OF THE LOWER CAMBRIAN OSA HORIZON IN THE SOUTH OF THE SIBERIAN PLATFORM (BOLSHETIRSKAYA 7 WELL)

The section of the Osa Subformation of the Usolka Formation of the Lower Cambrian Tommotian stage penetrated by the Bolshetirskaya 7 well in the south of the Nepa-Botuoba anteclise has been studied. As a result of lithological-facies investigations, seven lithological types of rocks were identified, they are regularly replaced by each other along the section. Facies environments of the reef complex were dеtected: bar bank, rear part of the reef, organogenic bioherm bildup, reef rear bars, reef buildup, core of reef buildup. In the section of the subformation, three fourth-order sequences are identified. The sequence boundaries are fixed by subaerial hiatuses represented in the core by sedimentation breccias, karst zones. The largest lowering of sea level, in terms of amplitude and duration, is confined to the border of the second and third sequences. The conducted biostratigraphic analysis confirms the Lower Cambrian age. Remains of calcareous algae Renalcis polymorphum, R. gelatinosum, R. granosum, Botomaella zelenovi were found. Small shell fauna of the genus of Namacalathus Grotzinger, Watt ers et Knoll. also was found. It has global distribution in the Lower Vendian (Ediacaran) deposits in Namibia, Brazil, Canada, Oman, Spain, China, Russia, etc.

Description of a new species Gyraulus (Pulmonata: Planorbidae) from the land thermal spring Khakusy of Lake Baikal

A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the north-eastern shore of Lake Baikal. The description of Gyraulustakhteevi sp. n. includes morphological characters and gene sequences (COI of mtDNA) for the species separation from sister taxon Gyraulusacronicus (A. Férussac, 1807) collected from the small Krestovka River in-flowing into the south-western part of the Lake. The new species differs from G.acronicus in small shell size of adults, having smaller number of prostate folds (maximal up to 26 in G.takhteevi n. sp. vs. 40 in G.acronicus), a short preputium (approximately twice shorter than the phallotheca), and an elongated bursa copulatrix. The population of Gyraulustakhteevi sp. n. consists of two co-existent morphs: one of them has a narrow shell spire and the second is characterized by wide spire similar to the shell of G.acronicus. One of the two revealed haplotypes of the new species includes both morphs, while the second consists of snails with wide spired shells.

Modified Svensson’s Formula for More Accurate Burst Pressure Predictions of Thin Cylindrical Shells With Small Shell Length to Diameter Ratios

For process safety management purposes, it is often required in industries to perform burst pressure calculations for pressurized equipment subjected to internal deflagrations. In predictions of burst pressures of vessels with short cylindrical shell sections, the stiffening effects of heads are often overlooked, which may lead to underestimated results. In this paper, a new improved method is proposed for predictions of burst pressures of thin cylindrical shells with small shell length to diameter ratios (L/D) at ambient temperature. The idea is to use the Svensson’s formula, modified by a factor that accounts for the effects of small L/D ratios, head types, and materials for more accurate predictions. Tables of such factors are developed based on study results from a series of elastic-plastic Finite Element Analyses including large displacement effect for different L/D ratios, thicknesses, materials, and head types. Some example problems are presented to validate the method.

Estimation of effects of tributyltin (TBT) bioaccumulation using the imposex character in marine gastropods (Thais tuberosa and Monodonta labio)

The effects of tributyltin (TBT) have been estimated using imposex characters in two species of marine gastropods, Thais tuberosa and Monodonta labio, at 3 different locations along the Minahasa Peninsula, northern part of Sulawesi Island: Manado Bay Waters, Bitung Coastal Waters, and Tateli Coastal Waters as a control area. The estimation was done by comparing the percentage of female imposex (I) at different body size (small: shell length ≤ 25 mm; large: shell length >25 mm), and measuring the concentration of TBT in sediments and soft part of the gastropod samples. The highest I value was found in small sized T. tuberosa from Manado Bay Waters (63%) and large sized T. tuberosa from Bitung Coastal Waters (60%). Small and large sized M. labio had their highest I value, 30% and 44% respectively, in the samples from Manado Bay Water and Bitung Coastal Waters. The occurence of imposex in both speciesis correlated with the high concentration of TBT in sediments and soft part of the marine gastropod samples© Kajian tentang pendugaan pengaruh bioakumulasi logam berat tributyltin (TBT) menggunakan karakter imposeks pada gastropoda laut (Thais tuberosa dan Monodonta labio) telah dilakukan. Sampel diambil dari 3 lokasi di perairan sepanjang Semenanjung Minahasa, Pulau Sulawesi bagian Utara, yaitu Perairan Teluk Manado (PTM), Perairan Bitung (PBT), dan Perairan Pantai Tateli (PPT) sebagai lokasi kontrol. Pendugaan dilakukan dengan cara membandingkan persentase individu imposeks (I) sampel ukuran kecil (K; panjang cangkang ≤ 25 mm) dan ukuran besar (B; panjang cangkang >25 mm), dan pengukuran konsentrasi TBT pada sedimen dan bagian lunak sampel gastropoda laut. Nilai I tertinggi adalah pada T. tuberosa ukuran K asal PTM, sebesar 63%, dan ukuran B asal PBT, sebesar 60%.Untuk M. labio baik ukuran K maupun B, nilai I tertinggi adalah pada sampel asal PTM dan PBT, masing-masing sebesar 30% dan 44%. Kejadian imposeks pada kedua jenis sampel ini didukung dengan konsentrasi TBT pada sedimen dan jaringan gastropoda laut yang tinggi©