Identification and characterization of human hematopoietic mesoderm.

The embryonic mesoderm comprises heterogeneous cell subpopulations with distinct lineage biases. It is unclear whether a bias for the human hematopoietic lineage emerges at this early developmental stage. In this study, we integrated single-cell transcriptomic analyses of human mesoderm cells from embryonic stem cells and embryos, enabling us to identify and define the molecular features of human hematopoietic mesoderm (HM) cells biased towards hematopoietic lineages. We discovered that BMP4 plays an essential role in HM specification and can serve as a marker for HM cells. Mechanistically, BMP4 acts as a downstream target of HDAC1, which modulates the expression of BMP4 by deacetylating its enhancer. Inhibition of HDAC significantly enhances HM specification and promotes subsequent hematopoietic cell differentiation. In conclusion, our study identifies human HM cells and describes new mechanisms for human hematopoietic development.

Research Progress on the Application of Topological Phase Transition Materials in the Field of Memristor and Neuromorphic Computing.

Topological phase transition materials have strong coupling between their charge, spin orbitals, and lattice structure, which makes them have good electrical and magnetic properties, leading to promising applications in the fields of memristive devices. The smaller Gibbs free energy difference between the topological phases, the stable oxygen vacancy ordered structure, and the reversible topological phase transition promote the memristive effect, which is more conducive to its application in information storage, information processing, information calculation, and other related fields. In particular, extracting the current resistance or conductance of the two-terminal memristor to convert to the weight of the synapse in the neural network can simulate the behavior of biological synapses in their structure and function. In addition, in order to improve the performance of memristors and better apply them to neuromorphic computing, methods such as ion doping, electrode selection, interface modulation, and preparation process control have been demonstrated in memristors based on topological phase transition materials. At present, it is considered an effective method to obtain a unique resistive switching behavior by improving the process of preparing functional layers, regulating the crystal phase of topological phase transition materials, and constructing interface barrier-dependent devices. In this review, we systematically expound the resistance switching mechanism, resistance switching performance regulation, and neuromorphic computing of topological phase transition memristors, and provide some suggestions for the challenges faced by the development of the next generation of non-volatile memory and brain-like neuromorphic devices based on topological phase transition materials.

Activating HfX2 (X = S, Se and Te) for the hydrogen evolution reaction by introducing defects: a first-principles study.

An ideal catalyst should have a relative hydrogen adsorption Gibbs free energy (ΔGH) close to zero [J. K. Nørskov, et al., J. Electrochem. Soc., 2005, 152, J23]. However, most of the known catalysts cannot reach this standard. Based on first-principles calculations, we studied the hydrogen evolution reaction (HER) catalytic performance of pristine and defect (including vacancy and heteroatom doping) structures in terms of its ΔGH. We found that the ΔGH values of Co-doped HfS2 and P-doped HfSe2 are extremely close to zero, even closer than that of Pt (111), indicating that they are excellent catalysts. Moreover, we found that the source of the HER catalytic performance of Co-doped HfS2 is the reduction of electron accumulation of the active site S atom. Our work provides two potential ideal catalysts and provides guidance for the experimental group to search for suitable catalysts.

Pressure-Induced Phase Diagram and Electronic Structure Evolves during the Insulator-Metal Transition of Bulk BiFeO3.

BiFeO3 is the most widely known multiferroic at room temperature, possessing both ferroelectricity and antiferromagnetism. It has high Curie temperature and Néel temperature, i.e., 1103 and 643 K, respectively. Despite these unique properties, the pressure-induced phase diagram of bulk BiFeO3 has remained controversial. Based on the ab initio evolutionary algorithm, we systematically searched for the potential stable structures of bulk BiFeO3 at 0-50 GPa. It is identified that there are five pressure-induced phase transition sequences R3c-G-AFM →(5GPa) C2/m-G-AFM →(15GPa) Pnma-G-AFM →(24GPa) Pnma-FM →(35GPa) Imma-FM →(45GPa) Cmcm-FM, which provided a comprehensive pressure-induced phase diagram. As the pressure increases, we discovered an interesting phenomenon: a pressure-induced magnetic sequence transition, i.e., BiFeO3 transitions from an antiferromagnetic to a ferromagnetic sequence. Concurrently, the electronic structure evolves during the insulator-metal transition, influenced not only by the pressure but also by the phase transition. Our research has elucidated the long-standing question of the phase transition sequence of the BiFeO3 system under pressure and provided theoretical support for the insulator-metal transition.

Prediction of the hardest BiFeO3 from first-principles calculations.

BiFeO3 is the only material with ferroelectric Curie temperature and Néel temperature higher than room temperature, making it one of the most well-studied multiferroic materials. Based on an ab initio evolutionary algorithm, we predicted a new cubic C-type antiferromagnetic structure (Fd3̄m-BiFeO3) at ambient pressure. It was found that Fd3̄m-BiFeO3 is the hardest BiFeO3 (Vickers hardness ∼ 9.12 GPa), about 78% harder than R3c-BiFeO3 (the well-known multiferroic material), which contributes to extending the life of BiFeO3 devices. In addition, Fd3̄m-BiFeO3 has the largest shear modulus (83.74 GPa) and the largest Young's modulus (214.72 GPa). Besides, we found an interesting phenomenon that among the common multiferroic materials (BiFeO3, BaTiO3, PbTiO3, SrRuO3, KNbO3, and BiMnO3), Pnma-BiMnO3 has the largest bulk modulus, and its bulk modulus is about 15% larger than that of Fd3̄m-BiFeO3. However, its Vickers hardness (4.47 GPa) is much smaller than that of Fd3̄m-BiFeO3. This is because the Vickers hardness is proportional to the shear modulus and the shear modulus of Fd3̄m-BiFeO3 is larger than that of Pnma-BiMnO3. This work provides a deeper and more comprehensive understanding of BiFeO3.

Enhanced electronic and optical properties of multi-layer arsenic via strain engineering.

Solar cell is a kind of devices for renewable and environmentally friendly energy conversion. One of the important things for solar cells is conversion efficiency. While much attention has been drawn to improving efficiency, the role of strain engineering in two-dimensional materials is not yet well-understood. Here, we propose aPmc21-As monolayer that can be used as a solar cell absorbing material. The bandgap of single-layerPmc21-As can be tuned from 1.83 to 0 eV by applying tensile strain, while keeping the direct bandgap characteristic. Moreover, it has high light absorption efficiency in the visible and near-infrared regions, which demonstrates a great advantage for improving the conversion efficiency of solar cells. Based on the tunable electronic and optical properties, a novel design strategy for solar cells with a wide absorption range and high absorption efficiency is suggested. Our results not only have direct implication in strain effect on two-dimensional materials, but also give a possible concept for improving the solar cell performance.

New multiferroic BiFeO3 with large polarization.

BiFeO3 is one of the most widely studied multiferroic materials, because of its large spontaneous polarization at room temperature, as well as ferroelasticity and antiferromagnetism. Using an ab initio evolutionary algorithm, we found two new dynamically stable BiFeO3 structures (P63 and P6322) at ambient pressure. Their energy is only 0.0662 and 0.0659 eV per atom higher than the famous R3c-BiFeO3, and they have large spontaneous polarization, i.e., 71.82 µC cm-2 and 86.06 µC cm-2, respectively. The spontaneous polarization is caused by the movement of the Bi3+ atom along the [001] direction and mainly comes from the 6s electron of Bi3+. Interestingly, there is no lone pair electron of Bi3+, which is different from R3c-BiFeO3. The new structures have the same magnetic configurations as R3c-BiFeO3 (G-type antiferromagnetism), but they are characterized by one-dimensional channels linked by a group of two via surface-sharing oxygen octahedra. Due to the similarity of the two structures, both of them have indirect bandgap structures, and the bandgaps are 2.62 eV and 2.60 eV, respectively. This work not only broadens the structural diversity of BiFeO3 but also has constructive significance for the study of spontaneous polarization of new structures of multiferroic materials.

Learning Enhanced Feature Responses for Visual Object Tracking.

Visual object tracking is an important topic in computer vision, which has successfully utilized pretrained convolutional neural networks, such as VGG and ResNet. However, the features extracted by these pretrained models are high dimensional, and the redundant feature channels reduce target localization and scale estimation precision, leading to tracking drifting. In this paper, a novel visual object tracking method, called learning enhanced feature responses tracking (LEFRT), is proposed, which adopts the target-specific features to enhance target localization and scale estimation responses. First, a channel attention module, called target-specific network (TSNet), is presented to reduce the redundant feature channels. Secondly, the scale estimation network (SCENet) is introduced to extract spatial structural features to generate a more precise response for the scale estimation. Extensive experiments on six tracking benchmarks, including LaSOT, GOT-10k, TrackingNet, OTB-2013, OTB-2015, and TC-128, demonstrate that the proposed algorithm can effectively improve the precision and speed of visual object tracking. LEFRT achieves 90.4% precision and a 71.2% success rate on the OTB-2015 dataset, improving the tracking methods based on the pretrained features.

Prevention schemes for future fresh agricultural products (FAPs) supply chain: mathematical model and experience of guaranteeing the supply of FAPs during the COVID-19 pandemic.

BACKGROUND: The COVID-19 outbreak caused short-term disruptions in the supply chain of fresh agricultural products (FAPs), which exposed the vulnerability of the existing FAP supply chain. With pandemic control being widely coordinated, the supply chain of FAPs was gradually optimized and improved. However, after the outbreak of COVID-19, achieving an effective supply of FAPs in future pandemics has become a key issue. The present work therefore aimed to construct a three-level supply chain based on the Stackelberg game model, consisting of suppliers, third-party logistics (TPL), and retailers, to guarantee the supply of FAPs. COVID-19 pandemic factors such as virus infection coefficients and pandemic prevention efforts were fully integrated into the model. RESULTS: Compared with the wholesale prices of FAPs, preservation efforts and pandemic prevention efforts have huge impacts on the retail prices of FAPs. When suppliers are in the leading position, the quality assurance effort level is positively correlated with the optimal profit. Compared with this situation, when FAP retailers are in the leading position, TPL providers show higher levels of pandemic prevention effort and FAP preservation effort. With an increase in consumer preference for pandemic prevention, the profits of supply-chain members when FAP retailers are in the leading position will gradually increase. CONCLUSION: This study reveals an effective supply mechanism for FAPs in metropolitan areas during the COVID-19 pandemic and describes the authors' experience of guaranteeing the quality and safety of FAPs for future pandemic cases. © 2021 Society of Chemical Industry.

Isolation and utilization of tobacco-based cellulose nanofiber (TCNF) for high performance reconstructed tobacco sheet (RTS).

Nowadays, wood pulp addition (such as softwood, hardwood, etc.) into manufacture reconstructed tobacco sheet (RTS) via a paper-making process is a feasible and sustainable technology. However, the addition of wood pulp in RTS would weaken the tobacco fragrance of cigarette by bring wood gas when smoking. In this study, a practical and feasible pretreatment by hot water/cooking process combined with cationic modification/homogenization treatment was proposed to directly isolate desirable cellulose nanofibers from tobacco stem, named TCNF. The obtained TCNF was applied in the preparation of RTS to improve its physical properties but with a reduced wood pulp proportion (from 25 wt% decreased to 16 wt%). Results showed that TCNF exhibit a similar morphology with wood based nanocellulose, and that the addition of TCNF (0.5 wt% based dried tobacco pulp) can substitute 9 % of wood pulp compared with that of the control at the similar physical properties.

[Correlation between special A/O genotype and the O phenotype].

OBJECTIVE: To explore the correlation between special A/O genotype and the O phenotype. METHODS: Group O samples with partially reduced or lack of isoagglutinins were collected to determinate the ABO genotype with a PCR-sequence specific primer (PCR-SSP) assay. Seven samples with A/O genotype were selected for further study. Serological tests including forward and reverse typing, H antigen determination and adsorption/elution were carried out with a tube method. Genomic DNA was genotyped by amplifying and sequencing of the coding regions of exons 1 to 7 of the ABO gene. RESULTS: Seven samples were serotyped as group O by the forward typing test. However, reduced anti-A activity was found in 5 samples by the reverse typing test, reduced anti-A and anti-B activities were found in 1 sample, and no anti-A isoagglutinin activity was found with 1 sample. H antigen was determined in all samples by routine serologic method. Neither anti-A nor anti-B was eluted from red cells derived from all samples. Three samples were genotyped as Ael02/O02, whilst the remainders were Ael02/O13, Ael02/O65, Am04/O75, Ael06/O02, respectively. CONCLUSION: Special A/O genotype may not express the A antigen, leading to the generation of group O red cells. Reduced or missed anti-A activity is the typical serological feature of this special group of O phenotype, for which ABO*Ael02 and ABO*O02 are the major alleles. Group O individuals with isoagglutinin detection problem should be grouped by serological tests and genomic DNA analysis.

[Identification of a novel ABO B(A)07 allele].

OBJECTIVE: To explore the molecular basis for a novel B(A) phenotype. METHODS: Genomic DNA was abstracted from peripheral blood sample from the proband. ABO genotyping were carried out with sequence specific primer PCR (PCR-SSP). Exons 6 and 7 of the ABO gene were amplified with PCR and sequenced. RESULTS: Anti-A serum could not be adsorbed or eluted by the donor's red blood cells, and no irregular antibodies were found in the plasma. PCR-SSP showed that the ABO genotype of the donor was ABO *B/O. Sequencing results showed that one of the alleles was ABO *O02, while the other could not be defined but contained the following mutation points, 297A>G, 526C>G, 657C>T, 701C>T, 703G>A, 796C>A, 803G>C, and 930G>A. The data was accepted by the GenBank (the loading code was KM974887) and the Blood Group Antigen Mutation Database, and was confirmed to be a novel allele of B(A). CONCLUSION: A novel allele ABO *B(A)07 with 701C>T has been identified, which may facilitate further study on blood antigen variants and typing of the blood groups.

[Phenotype Types and Genetic Mutation Mechanism of Rhesus D Variant Individuals].

OBJECTIVE: To explore the phenotype types and genetic mutation mechanism of Rhesus D variant individuals. METHODS: Fouty-eight peripheral blood samples of pregnancies and blood donors who had been identified as Rhesus D variant by using routine serologic methods were collected from January 2013 to October 2015 in our center. The multiple ligation-dependent probe amplification(MLPA) was used to determine the RHD after genomic DNA had been extracted from the blood sample, then the data including gene copy number variations, point mutations, deletions and hybrid fusions were analyzed by GeneMarker software. All exons of blood sample RHD were amplified via PCR and analyzed by sequencing when its MLPA results were not in accordance with serologic results. Cloning and haplotype sequencing were performed if novel allele had been found. RESULTS: Rh phenotypes of the 48 samples were typed as following: 20 cases out of 48 were CcDee(41.7%, 20/48),12 cases were ccDEe (25%,12/48), 11 cases were CCDee(22.9%, 11/48), 5 cases were CcDEe (10.4%, 5/48), respectively. The MLPA analysis showed that 38 cases possessed only 1 variant allele(RHD zygosity was Dvd), while 10 cases possessed 2 variant alleles(RHD zygosity was DvDv). In Dvd type individuals, point mutations were found in 18 cases and RHD/CE hybrid fusions were found in 20 cases. In DvDv individuals, point mutations combined with RHD/CE hybrid fusions were found in 9 cases, deletion combined with RHD/CE hybrid fusions were found in 1 case. Variant alleles analysis basing on MLPA showed that 14 cases were weak D 15 and 22 cases were RhD VI type 3, however, the variant alleles were not identified in 7 cases due to lack of detecting probes and were identified via sequencing analysis. Two novel mutations, 79-81delCTC and 689G>A were also certificated by sequencing in 2 cases. CONCLUSION: CcDee is the major Rh phenotype in RhD variants, weak D 15 and RhD VI type 3 are the main serologic type of RhD variants, point mutation and RHD/CE hybrid fusions are main molecular mechanism for RhD variant phenotype. Besides, 79-81delCTC and 689G>A are two novel alleles.

[Immunoserology and RHD Genotype Analysis of DVI Type 3 Genotype Pregnant Women with Anti-D].

OBJECTIVE: To performe the immuneserological and RHD Genotype analyses for DVI type 3 genotype pregnemt women with anti-D. METHODS: RhD blood type of this pregnant women was identified by common serological methods, then the blood group specific antibodies was screened and identified; the polymerase chain reaction-sequence specific primer(PCR-SSP) was used to identify the pregnant women's RHD genotype; RhD blood group for the pregnant women, her spouse and daughter was genogrouped and genetically analyzed by multiplex ligation-dependent probe amplification(MLPA). The heredity of this family was analyzed finally. RESULTS: The titer of IgG anti-D in the pregnant woman serum was 1:8; the PCR-SSP showed that the 3rd to 6th exons of RHD gene were missing in the pregnant woman. the genotype of pregnant woman was identified as DVI type 3; the MLPA analysis showed that this pregnant women owned only one RHD allele with 3rd to 6th exons missed, and her genotype was identified as CDVIe/cde; her spouse was identified as CDe/CDe homozygous genotype, and her daughter as CDe/CDVIe. CONCLUSION: Accurate identification of RhD blood type is of great significance for a safe and effective clinical blood transfusion strategy, and for taking appropriate measures to prevent hemolytic disease of newborn (HDN) at women childbearing age.

The summary of FUT1 and FUT2 genotyping analysis in Chinese para-Bombay individuals including additional nine probands from Guangzhou in China.

BACKGROUND: The para-Bombay phenotype is characterized by the absence or weak expression of ABH antigens on the surface of red blood cells, but normal expression in saliva. STUDY DESIGN AND METHODS: The para-Bombay phenotype of the nine Chinese probands was identified by standard serologic techniques. The coding regions of FUT1 and FUT2 genes were amplified by polymerase chain reaction and then directly sequenced. ABO genotyping was performed by polymerase chain reaction with sequence-specific priming method. The FUT1 and FUT2 genotypes and the distribution in all reported Chinese para-Bombay individuals including our study were also summarized. RESULTS: Five FUT1 genotypes, h1h3 (n = 3), h1h2 (n = 3), h1h1 (n = 1), h3h3 (n = 1), and h2h3 (n = 1), and three functional FUT2 genotypes, Se(357) Se(357) (n = 4), Se(357) Se(357, 716) (n = 4), and Se(357) Se(357, 385) (n = 1) described before were identified in nine probands. CONCLUSIONS: The review of the literature shows that a total of 17 FUT1 alleles and four FUT2 alleles (Se(357), Se(357,716), Se(357 385), Se) have been identified in Chinese para-Bombay individuals. The four FUT1 alleles, h1 (547delAG), h2 (880delTT), h3 (C658T), and h4 (C35T; A980C) are most prevalent, which account for more than 90% of all allele counts and are essential to be involved when developing para-Bombay genotyping kit for Chinese.

[Anti-Mur screening and Mur antigen genotyping of voluntary blood donors in Guangzhou].

OBJECTIVE: To investigate the frequency of anti-Mur and Mur antigen among blood donors in Guangzhou to provide evidence for guiding clinical transfusion and prenatal screening. METHODS: DG Gel Coombs cards were used to screen active anti-Mur at 37 degrees celsius; from 2725 blood donors. Multiplex ligation-dependent probe amplification (MLPA) was used to genotype Mur antigen from 91 blood donors, and human anti-Mur serum was used to verify the phenotypes deduced from the genotypes. RESULTS: The frequency of anti-Mur and genotyped Mur antigen was 0.04% (1/2725) and 6.59% (6/91), respectively, and the phenotyping results were consistent with the genotyping results. CONCLUSION: The blood donors in Guangzhou show a low frequency of anti-Mur and a relatively high frequency of Mur antigen. Genotyping using MLPA allows Mur antigen genotyping when commercial anti-Mur is not available.

[Serological and genetic study of a pedigree featuring a rare p phenotype].

OBJECTIVE: To explore genetic background of a pedigree with a rare p phenotype from Guangdong province. METHODS: The rare p phenotype was identified by a conventional serologic method. With genomic DNA of proband and family members extracted, exon 3 of alpha-(1,4)galactosyltransferase (A4GALT) gene was amplified with PCR and analyzed by direct sequencing. The mutation found in the pedigree was screened in a normal population using direct sequencing. RESULTS: The proband and 4 family members with the rare p phenotype have all carried a point mutation c.100G>A (p.Val34Ile) in combination with a deletion-insertional mutation c.418_428del11ins34(p.Gln139Trpfs*72), which renders a compound mutation of A4GALT gene. One family member with P2 phenotype has carried a same heterozygous mutation. Of the 100 healthy donors, 5 have carried a heterozygous point mutation c.100G>A, and none carried the deletion-insertional mutation c.418_428del11ins34. CONCLUSION: The rare p phenotype of the pedigree has resulted from a compound mutation of the A4GALT gene, which is in keeping with a recessive inheritance pattern of the p phenotype.

[High-throughput genotyping multiplex ligation-dependent probe amplification for assisting diagnosis in a case of anti-Di(a)-induced severe hemolytic disease of the newborn].

OBJECTIVE: To report a rare case of hemolytic disease of the newborn (HDN) with kernicterus caused by anti-Di(a) diagnosed using high-throughput genotyping multiplex ligation-dependent probe amplification (MLPA). METHODS: Conventional serological methods were used to detect the antibodies related with HDN. The genotypes of more than 40 red blood cell antigens for the newborn and her parents were obtained using the high-throughput MLPA assay. The antibody titers were tested using a standard serological method. RESULTS: The unknown antibody against the low-frequency antigens was predicted based on the primary serological tests. The genotyping results for more than 40 red blood cell antigens of the newborn and her parents showed incompatible antigens of MNS and Diego blood group system, indicating the existence of anti-N or anti-Di(a). Further serological tests confirmed anti-Di(a) existence in the plasma of the newborn and her mother. The titer of anti-Di(a) in the mother's plasma was 1:32. CONCLUSION: Severe HDN including kernicterus can result from anti-Di(a). High-throughput genotyping MLPA assay can help type some rare antigens in complicated cases. The reagent red cell panels including Di(a)-positive cells are necessary in routine antibody screening test in Chinese population.

[Effect of antisense oligonucleotide against telomerase in rat spermatogonia and its reactivity to cytokine].

OBJECTIVES: To study the change of telomerase activity in rat spermatogonia when the telomerase RNA was enclosed, and reactivity of the change to cytokine(SCF, TGF-beta 1). METHODS: The antisense oligonucleotides(PS-ASON) of telomerase was transfected into proliferating spermatogonia in vitro with the liposomes as the vector. Then the cytokine, stem cell factor (SCF) or transforming growth factor-beta 1(TGF-beta 1), was added. The proliferative activity of the spermatogonia was determined before and after the inhibition by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide]assay. The change of telomerase activity was detected by telomeric repeat amplification protocol (TRAP). RESULTS: 1 mumol/L PS-ASON obviously downregulated the telomerase activity and inhibited spermatogonia proliferation. When the inhibition was over, the activity recovered to some extent(P < 0.01). Growth factors can regulate the spermatogonia after inhibition, SCF may improve the activity of telomerase and the proliferation of spermatogonia. Adversely, TGF-beta 1 may inhibit the recovery of telomerase activity. CONCLUSIONS: To inhibit spermatogonia telomerase activity antisensely can limit the proliferation of spermatogonia efficiently, which was regulated by cytokine. This method might be a new and efficient way in male birth control.