Two new species of the genus Flagellozetes Balogh, 1970 (Acari: Oribatida: Galumnidae) from Vietnam

Oribatid mite fauna of Vietnam is most studied among countries of Continental Southeast Asia but due to the brief history of detailed research, discoveries of new species are expected. Descriptions of two new species of oribatid mites (Oribatida) of the family Galumnidae—Flagellozetes (Cosmogalumna) sacculus sp. nov. and F. (C.) lineatus sp. nov.—are presented based on specimens collected from rainforest soil of Bi Dup—Nui Ba National Park (southern Vietnam). F. (C.) sacculus sp. nov. differs from other species by the presence of saccules and rare diamond-shaped granules on pteromorphs. F. (C.) lineatus sp. nov. differs from F. (C.) ekaterinae (Ermilov & Friedrich, 2016) and F. (C.) dongnaiensis (Ermilov & Anichkin, 2013) by the presence of striate pteromorph, genital and anal plates, median pore, and centrodorsal part of notogaster ornamentation represented by neural ridges band.

Pore Structural Features of Granite under Different Temperatures

To explore the effects of thermal actions on the pore structural features of granite, scanning electron microscope (SEM) and mercury injection experiments were carried out on granite after thermal treatment (25 °C to 400 °C). The pore structure was investigated from various perspectives, including the capillary pressure curve, the pore–throat ratio, the median saturation pressure, the median pore–throat radius, the porosity, the pore volume, and the pore size distribution. Based on mercury intrusion test data, the Winland model of permeability prediction was modified for a high-temperature tight granite reservoir. The results showed that: (1) As the temperature rose, the mercury injection curve was gradually flattened, and the mercury ejection efficiency gradually increased. Meanwhile, the pore–throat ratio and the median saturation pressure decreased exponentially, and the pore connectivity was enhanced. (2) The median pore–throat radius and the porosity of granite increased exponentially as the temperature increased. Above 200 °C, the median pore–throat radius and the porosity increased substantially. (3) The pore volumes of the transitional pores, mesopores and macropores, and the total pore volume inside the granite, increased as the temperature rose. Especially above 200 °C, the transitional pores and the mesopores were prominently developed, and the pore volumes of the transitional pores and the mesopores took up a significantly greater proportion of the total pore volume. (4) As the temperature rose, the pore size distribution of granite became more extensive, the pore–throat structure was obviously developed, and the pore–throat connectivity was enhanced. (5) The relationship between the micropores’ characteristic parameters and the macro-permeability in engineering was established though a modified Winland model, and the modified Winland model had a better prediction effect. The findings provide a solid basis for rock geothermal mining projects and related geotechnical engineering.

New methods for assessing brick resistance to freeze-thaw cycles

The aim of this research is to analyse the reliability of the existing methods, and find new ones, for assessing brick resistance to freeze-thaw cycles. A series of bricks were tested against a range of properties; compressive strength ratios pre- to post-freezing and Maage’s factor, were calculated. Using a database created in this way, an analysis of existing classifiers was carried out and new ones were established based on which bricks could be classified into resistant and non-resistant to freeze-thaw cycles. The median pore radius, the ratio of compressive strengths pre- to post-freezing and the water desorption coefficient at 180-360 minutes proved to be good classifiers with a clearly specified cut-off for the distinction between resistant and non-resistant bricks with an acceptable risk of a wrong decision. The ratio of compressive strengths pre to post freezing and the water desorption coefficient at 180-360 minutes were described using the pore system in the brick.

A new species of Pergalumna (Acari, Oribatida, Galumnidae) from Bolivia, with updated identification key to known species of the genus from the Neotropical region

A new species of Pergalumna (Oribatida, Galumnidae) is described from leaf litter of rain forest in the Espejillos environs near the Bolivian Ambor National Park. Pergalumna espejillosensis sp. nov. is similar to Pergalumna nasica Pérez-Íñigo & Baggio, 1980 in the presence of protruding rostrum, three pairs of rounded/oval notogastral porose areas and minute interlamellar seta, and in the absence of dorsosejugal suture, but differs by the smaller body length, setiform bothridial seta and long lamellar seta, and the absence of a median pore. An identification key to known species/subspecies of the genus from the Neotropical region is presented.

Two new and a newly recorded species of the genus Pergalumna (Acari, Oribatida, Galumnidae) from China

Two new species, Pergalumna clava n. sp. and Pergalumna pilosus n. sp., and a newly recorded species, Pergalumna amamiensis Aoki, 1984 of oribatid mites are described and illustrated from China. Pergalumna clava n. sp. is different from most known species of Pergalumna in the dorsosejugal suture complete; developed four pairs notogastral porose areas, Aa transverse irregular wedge; short interlamellar seta and bothridial seta clavate. Pergalumna pilosus n.sp. different from most known species of Pergalumna in the dorsosejugal suture complete; Aa porose area transverse irregular wedge; longer interlamellar barbed; median pore and postanal porose area present.

Three new species of oribatid mites of the family Galumnidae (Acari, Oribatida) from South Africa

Three new species of oribatid mites of the family Galumnidae are described from soil and coniferous litter of Hogsback State Forest, Eastern Cape Province, South Africa. Pilogalumna hogsbackensis sp. nov. differs from Pilogalumna tenuiclava and P. ornatula by the presence of elongate oval postanal porose area and narrowly unilaterally dilated bothridial head. Pergalumna amatholensis sp. nov. differs from Pergalumna distincta by the presence of smaller body size, rounded rostrum, unilaterally dilated bothridial head, one pair of notogastral porose areas Aa, and the localization of opisthonotal gland opening and lyrifissure im. Stictozetes ihaguensis sp. nov. differs from all species of the genus by presence of bothridial seta with narrowly dilated head and median pore in both genders. An identification key to known species of Stictozetes is presented.

A new species of Pergalumna (Acari: Oribatida: Galumnidae) from southeastern Iran, including a key to all species of the genus from the Palaearctic region

A new species of oribatid mite of the family Galumnidae, Pergalumna sistanbaluchestanica sp. nov., is described and illustrated based on adult specimens from soil in Sistan and Baluchestan province, southeastern Iran. The new species is characterized by dentate rostrum; long interlamellar setae; long, setiform, finely barbed bothridial setae; complete dorsosejugal furrow; large, nearly triangular porose areas Aa; presence of median pore in females and males; large, elongated postanal porose area and large body size. The new species is most similar morphologically to P. seminervosa Mahunka & Mahunka-Papp, 2008, however, differs from it in morphology of bothridial setae and notogastral porose areas Aa and also by the surface ornamentation of the pteromorphs and genital plates; localization of setal alveoli la and lyrifissures im and body size. An identification key to known species of Pergalumna from the Palaearctic region is given.

Deformation of Tianjin soft clay and corresponding micromechanism under cyclic loading

The deformation of soft clays under cyclic loading is controlled by microfabric changes. Cyclic triaxial tests, scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) were conducted to investigate the deformation and the corresponding micromechanism under cyclic loading. The correlations between the microparameters and deformation of Tianjin soft clay are discussed. The deformation increases linearly in the initial compression stage (number of cycles, N < 500), at a decreasing rate in the later shearing stage (N < 5000), and eventually stabilizes when the cyclic stress ratio (CSR) is 0.30. The probability entropy of both the soil particles and pores have a weak correlation with the deformation on the whole, reflecting a fluctuation within a small range in the initial compression stage. The correlations between the median pore diameter, median particle diameter, and specific surface area and the deformation are validated by using the gray correlation method. More specifically, the specific surface area and the deformation are highly correlated in the initial compression deformation stage. The median pore diameter and median particle diameter are highly correlated with deformation in the later shearing deformation stage.

The Effect of Fracturing Fluid Saturation on Natural Gas Flow Behavior in Tight Reservoirs

Hydraulic fracturing becomes an essential method to develop tight gas. Under high injection pressure, fracturing fluid entering into the formation will reduce the flow channel. To investigate the influence of water saturation on gas flow behavior, this study conducted the gas relative permeability with water saturation and the flow rate with the pressure gradient at different water saturations. As the two dominant tight gas-bearing intervals, the Upper Paleozoic Taiyuan and Shihezi Formations deposited in Ordos Basin were selected because they are the target layers for holding vast tight gas. Median pore radius in the Taiyuan Formation is higher than the one in the Shihezi Formation, while the most probable seepage pore radius in the Taiyuan Formation is lower than the one in the Shihezi Formation. The average irreducible water saturation is 54.4% in the Taiyuan Formation and 61.6% in the Shihezi Formation, which indicates that the Taiyuan Formation has more movable water. The average critical gas saturation is 80.4% and 69.9% in these two formations, respectively, which indicates that the Shihezi Formation has more movable gas. Both critical gas saturation and irreducible water saturation have a negative relationship with porosity as well as permeability. At the same water saturation, the threshold gradient pressure of the Taiyuan Formation is higher than the one in the Shihezi Formation, which means that water saturation has a great influence on the Taiyuan Formation. Overall, compared with the Shihezi Formation, the Taiyuan Formation has a higher median pore size and movable water saturation, but water saturation has more influence on its gas flow capacity. Our research is conducive to understanding the effect of fracturing fluid filtration on the production of natural gas from tight reservoirs.

Two new species of Galumna (Acari, Oribatida) from Andasibe-Mantadia National Park, Madagascar

Two new species of the subgenus Galumna (Galumna) (Oribatida, Galumnidae) are described from leaf litter of evergreen rain forest in eastern Madagascar. Galumna brevilineata sp. nov. differs from its closest species Galumna (Galumna) anuakensis Ermilov, 2019 and Galumna paracalcicola Ermilov & Anichkin 2014 by the length of interlamellar and lamellar setae, the localization of notogastral lyrifissures im, the ornamentation of anogenital region, the morphology of bothridial setae and postanal porose area, and the absence of median pore. Galumna (Galumna) paraarmatifera sp. nov. differs from its closest species Galumna armatifera Mahunka, 1996 by the morphology of bothridial setae and anal plates, and the length of circumpedal carinae. An identification key to species of Galumna (Galumna) of the calcicola-group (species with short lamellar lines) was presented.