Maximum age limitation in luminescence dating of Chinese loess using the multiple-aliquot MET-pIRIR signals from K-feldspar

Numerical dating of loess is important for Quaternary studies. Recent progress in post-infrared infrared-stimulated luminescence (pIRIR) signals from potassium-rich feldspar has allowed successful dating of Chinese loess beyond the conventional dating limit based on quartz optically stimulated luminescence (OSL) signals. In this study we tested the multiple-aliquot regenerative-dose (MAR) pre-dose multiple-elevated-temperature post-IR IRSL (pMET-pIRIR) procedure on samples from the palaeosol S5 (∼480 ka) and S8 (∼780 ka) layers from the Luochuan and Jingbian sections, respectively. The results show that (1) compared to sensitivity-corrected signal (Lx/Tx), a higher saturation dose is observed for the sensitivity-uncorrected MET-pIRIR signals (Lx), suggesting that MAR is advantageous for dating old samples; (2) negligible fading component can be achieved using the pMET-pIRIR procedure; (3) for the sample from the top of palaeosol S5, De values (1360 + 226/-167 Gy) broadly consistent with expected De (1550 ± 72 Gy) can be obtained using the sensitivity-uncorrected 300 °C MET-pIRIR signal. Our study suggests that a De value of about 1800 Gy may be the maximum dating limit of Chinese loess using the MAR pMET-pIRIR procedure.postprin

Decreasing the use of edible oils in China using WeChat and theories of behavior change: study protocol for a randomized controlled trial.

The consumption of edible oils in China has increased rapidly in recent years, and the total amount of edible-oil intake in the country has ranked first in the world. The choice and intake of edible oils, as a source of fats, are important factors that affect people's health. Many chronic diseases are closely associated with high-calorie and saturated-fat intake. The influence of traditional concepts that promote the use of edible oils among women, particularly housewives, plays a key role in a household's diet and nutrition because the diet-related knowledge, attitude and behaviour of housewives are dominant factors in planning and preparing their family's meals. WeChat, which was developed by Tencent, is a multipurpose messaging, social media and mobile payment application (app) in China. Described by Forbes as one of the world's most powerful apps, WeChat provides considerable convenience in disseminating knowledge. Accordingly, this study aims to design a pilot intervention to decrease the use of edible oils in Chinese households. The intervention, which is based on theories of behaviour change, will be implemented through WeChat. The study design is a randomised controlled trial that adopts knowledge, attitude and practice, social cognitive and stages of change theories as theoretical models. A total of 800 housewives between the ages of 25 and 45 years will be recruited on WeChat and from the communities in four areas (including rural and urban) in Chongqing, China. A self-administered questionnaire will be used to collect information regarding age, educational level, occupation, family members, edible-oil intake habits, knowledge of edible oils and WeChat usage habits. A total of 200 participants will be selected and randomly assigned to two equal-sized groups: group A (the intervention group) and group B (the control group). Group A will receive health education regarding edible oils for four consecutive weeks, whereas group B will be treated as the blank control. Each participant will complete a battery of knowledge, attitude and behaviour tests immediately, 3 months and 6 months after the intervention. In addition, weight, moisture rate, fat rate, visceral fat level and body mass index will be calculated using a multifunctional weighing scale, namely, Tanita BC-601 (Japan). The study is currently in the design stage. This study aims to increase knowledge and awareness of the appropriate use of edible oils, thereby encouraging participants to change behaviour by decreasing the intake of unhealthy levels of edible oils. It will be the first intervention to investigate the use of edible oils in China through WeChat. We predict that receiving health education regarding edible oils through WeChat will substantially improve the knowledge and attitude of the respondents. The members of the intervention group will have increased awareness and will be willing to decrease their use of edible oils to remain healthy. Results of this study may provide scientific evidence for the effect of health education through WeChat on edible oil-intake behaviour, thereby offering a comprehensive intervention to decrease the use of edible oils and promote a healthy lifestyle. Chinese Clinical Trial Registry (primary registry in the World Health Organisation registry network): ChiCTR-IOR-17013472 . Registered on 21 November 2017

A verified genomic reference sample for assessing performance of cancer panels detecting small variants of low allele frequency

BackgroundOncopanel genomic testing, which identifies important somatic variants, is increasingly common in medical practice and especially in clinical trials. Currently, there is a paucity of reliable genomic reference samples having a suitably large number of pre-identified variants for properly assessing oncopanel assay analytical quality and performance. The FDA-led Sequencing and Quality Control Phase 2 (SEQC2) consortium analyze ten diverse cancer cell lines individually and their pool, termed Sample A, to develop a reference sample with suitably large numbers of coding positions with known (variant) positives and negatives for properly evaluating oncopanel analytical performance.ResultsIn reference Sample A, we identify more than 40,000 variants down to 1% allele frequency with more than 25,000 variants having less than 20% allele frequency with 1653 variants in COSMIC-related genes. This is 5-100x more than existing commercially available samples. We also identify an unprecedented number of negative positions in coding regions, allowing statistical rigor in assessing limit-of-detection, sensitivity, and precision. Over 300 loci are randomly selected and independently verified via droplet digital PCR with 100% concordance. Agilent normal reference Sample B can be admixed with Sample A to create new samples with a similar number of known variants at much lower allele frequency than what exists in Sample A natively, including known variants having allele frequency of 0.02%, a range suitable for assessing liquid biopsy panels.ConclusionThese new reference samples and their admixtures provide superior capability for performing oncopanel quality control, analytical accuracy, and validation for small to large oncopanels and liquid biopsy assays.Peer reviewe

Photodegradation of organic pollutants RhB dye using UV simulated sunlight on ceria based TiO2 nanomaterials for antibacterial applications

To photo-catalytically degrade RhB dye using solar irradiation, CeO2 doped TiO2 nanocomposites were synthesized hydrothermally at 700 °C for 9 hrs. All emission spectra showed a prominent band centered at 442 nm that was attributed to oxygen related defects in the CeO2-TiO2 nanocrystals. Two sharp absorption bands at 1418 cm−1 and 3323 cm−1 were attributed to the deformation and stretching vibration, and bending vibration of the OH group of water physisorbed to TiO2, respectively. The photocatalytic activities of Ce-TiO2 nanocrystals were investigated through the degradation of RhB under UV and UV+ visible light over a period of 8 hrs. After 8 hrs, the most intense absorption peak at 579 nm disappeared under the highest photocatalytic activity and 99.89% of RhB degraded under solar irradiation. Visible light-activated TiO2 could be prepared from metal-ion incorporation, reduction of TiO2, non-metal doping or sensitizing of TiO2 using dyes. Studying the antibacterial activity of Ce-TiO2 nanocrystals against E. coli revealed significant activity when 10 μg was used, suggesting that it can be used as an antibacterial agent. Its effectiveness is likely related to its strong oxidation activity and superhydrophilicity. This study also discusses the mechanism of heterogeneous photocatalysis in the presence of TiO2

Magnetostratigraphy of a late Miocene-Pliocene loess-soil sequence in the western Loess Plateau in China

Eolian deposits of Pliocene age have never been reported from the western Loess Plateau in China. Here, a 73.7 m eolian sequence is dated using magnetostratigraphic method and micromammalian fossils. The polarity zonation correlates with the geomagnetic polarity timescale (GPTS), from Chron 3Br.1r to Chron 2An.3n, indicating an age from 7.10 to 3.52 Ma BP. The sequence is characterized by clear expression of eighty-four pairs of loess and soil layers while individual soils are basically indefinable for the eolian deposits of the same age in the eastern Loess Plateau, suggesting that the later has experienced other geological processes. This sequence extends the upper limit of the previously reported Miocene loess-soil sequences at Qinan into the Pliocene, about 3.52 Ma BP

Origin of the Miocene-Pliocene Red-Earth formation at Xifeng in northern China and implications for paleoenvironments

In the eastern Loess Plateau region of northern China, the Quaternary loess-soil sequences of the last 2.6 Ma are underlain by the Hipparion Red-Earth Formation. Magneto-stratigraphic studies suggest that it is a near continuous terrestrial record for the period from similar to7 to similar to2.6 Ma BP, and therefore, has great potential for the study of Asian paleoclimates. The origin of this formation is controversial and needs further study. In this work, the Xifeng Red-Earth section, a type section for the eastern Loess Plateau region, was studied using optical microscopic analysis, grain-size measurements, and both major- and trace-element geochemical properties to address questions of its origin and environmental implications. The results show that this formation consists of three parts. The Lower part (>6.2 Ma BP) is a water-reworked deposit related to alluvial and slope processes; the Middle part (from similar to6.2 to similar to3.6 Ma BP) was derived from in situ eolian dust deposition, but was significantly affected by groundwater oscillations; and the Upper part (from similar to3.6 to similar to2.6 Ma BP) is an eolian formation, similar to the Quaternary loess-soil sequence. The grain-size of the Upper part is significantly coarser than for the middle part, but finer than for the overlying loess. Because the eolian dust deposits in the middle reaches of the Yellow River were mainly transported from the deserts in northern China by the northwesterly winter monsoon wind and the westerlies, we interpret the eolian origin of the Middle and Upper Red-Earth formation, beginning approximately at 6.2 Ma BP, as an indication of the strengthening of the aridification of the Asian continent. Desert lands in Central Asia must have been formed at or by that time to provide a significant source of dust. However, the generally finer grain-size of the Red-Earth suggests a weaker transporting wind, and/or a more remote source. The latter implies a smaller extent of deserts than in the Quaternary. The high degree of similarity between the geochemical properties of the Red-Earth and loess samples seems to suggest a rather similar source areas and comparable dust-transporting trajectories. The removal of the dust deposits from groundwater influence and the increase in grain-size at similar to3.6 Ma BP are attributable to both tectonic and climatic causes. The initiation of these phenomena corresponds to an intensive uplift of the Tibetan Plateau and also to a simultaneous uplift of the sedimentary basins in the surrounding areas. It is also approximately synchronous with an increase in eolian mass accumulation rate in the North Pacific, both suggesting an increased continental aridity in the Asian dry lands, and an increasing intensity of transporting winds. (C) 2001 Elsevier Science B.V. All rights reserved

Late Miocene-Pliocene development of Asian aridification as recorded in the Red-Earth Formation in northern China

In northern China, the Late Miocene-Pliocene Hipparion Red-Earth Formation in the eastern Loess Plateau fills a gap of climate records between the well-known loess-soil sequences of the last 2.6 Ma and the Miocene loess-soil sequences from the western Loess Plateau. Earlier studies on type sections indicate that a major part of the Red-Earth Formation is also of windblown origin, covering the period from similar to7- 8 to similar to2.6 Ma BP. Because the eolian dust deposited in the region originated from the Asian desert lands, the Red-Earth must contain a record of the aridification history of the Asian interior. In this study, the Xifeng type section in the eastern Loess Plateau is studied to assess the development of Asian aridification during Late Miocene-Pliocene time. Eolian dust deposition continued at the central Loess Plateau since similar to6.2 Ma BP, indicating that sizable desert lands in the interior of Asia and the Asian winter monsoon must have been constantly maintained during Late Miocene -Pliocene time, and were able to provide a significant amount of eolian dust. The aridity in the source areas was stronger from similar to6.2 to similar to5 Ma BP and weaker from similar to5 to similar to3.6 Ma BP. Two major aridification steps are observed at similar to3.6 and similar to2.6 Ma BP, respectively. The intensification of eolian deposition at similar to3.6 Ma BP is synchronous with a suggested uplift of portions of the Tibetan Plateau. The general aridification history is also highly consistent with the ongoing high-latitude cooling and the consequent expansion of Arctic sea-ice/ice sheets during this interval. Our results therefore suggest that both Tibetan uplift and ice-building processes in the northern hemisphere were two prominent driving forces behind the long-term desertification in the interior of Asia during Late Miocene and Pliocene time. (C) 2004 Elsevier B.V. All rights reserved

Loess-soil sequences in southern Anhui Province: Magnetostratigraphy and paleoclimatic significance

Two parallel loess-soil sequences from Xuancheng and Fanchang in southern Anhui Province are dated using geomagnetic and luminescence methods. The Brunhes/Matuyama (B/M) reversal boundary is recognized within the lower part of the so-called Vermiculated Red Soil (VRS) in the Xuancheng section while the entire Fanchang sequence is of Brunhes age. This indicates that the most recent VRS in southern China, a stratigraphic marker and an indication of extremely warm-humid conditions, was formed during the middle Pleistocene, chronologically correlative with the S4 and S5 soil units in northern China. Microscopic and sedimentologic investigations reveal that eolian deposition started in this region at about 0.85 MaBP, roughly synchronous with the well-known Mid-Pleistocene climate change of global significance. The strengthening of both summer and winter monsoon circulations and the consequent river hydrological changes at that time would have provided favorable conditions for sustained eolian deposition in the middle-lower reaches of the Yangtze River since 0.85 MaBP

Numerical investigation of the dynamic compressive behaviour of rock materials at high strain rate

The dynamic compressive strength of rock materials increases with the strain rate. They are usually obtained by conducting laboratory tests such as split Hopkinson pressure bar (SHPB) test or drop-weight test. It is commonly agreed now that the dynamic increase factor (DIF) obtained from impact test is affected by lateral inertia confinement, friction confinement between the specimen and impact materials and the specimen sizes and geometries. Therefore, those derived directly from testing data do not necessarily reflect the true dynamic material properties. The influences of these parameters, however, are not straightforward to be quantified in laboratory tests. Therefore, the empirical DIF relations of rock materials obtained directly from impact tests consist of contributions from lateral inertia and end friction confinements, which need be eliminated to reflect the true dynamic material properties. Moreover, different rocks, such as granite, limestone and tuff have different material parameters, e.g., equation of state (EOS) and strength, which may also affect the DIF of materials but are not explicitly studied in the open literature. In the present study, numerical models of granite, limestone and tuff materials with different EOS and strength under impact loads are developed to simulate SHPB tests and to study the influences of EOS and strength, lateral inertia confinement and end friction confinement effects on their respective DIFs in the strain rate range between 1 and 1,000 s-1. The commercial software AUTODYN with user-provided subroutines is used to perform the numerical simulations of SHPB tests. Numerical simulation results indicate that the lateral inertia confinement, friction confinement and specimen aspect (L/D) ratio significantly influence DIF obtained from impact tests and the inertia confinement effect is different for different rocks. Based on the numerical results, quantifications on the relative contributions from the lateral inertia confinement and the material strain rate effect on DIF of granite, limestone and tuff material compressive strength are made. The effects of friction coefficient, L/D ratio and rock type on DIF are discussed. Empirical relations of DIF with strain rate for the three rock materials representing the true material strain rate effect are also proposed