A simple and efficient method for separation of 99mTc from 100Mo targets.

99mTc is regarded as the most important medical isotope, and its supply issues have garnered significant attention. A simple and efficient separation method was performed for the production of 99mTc from 100Mo target in this study. The entire process involves accelerator irradiation, 99mTc/100Mo separation, and target material recovery. The key aspect is separation process, which including the high-temperature conversion of metal molybdenum targets and the selective solution of 99mTc with normal saline. This method can separate highly pure 99mTc within 1.5 h, with a separation efficiency exceeding 80%. The reagents used in the separation process are minimal, resulting in less radioactive waste. Additionally, the target material is easy to reclaim, with a recovery rate of over 95%.

Anti-Inflammatory Diet and Protein-Enriched Diet Can Reduce the Risk of Cognitive Impairment among Older Adults: A Nationwide Cross-Sectional Research.

BACKGROUND: Cognitive impairment (CI) is a common mental health disorder among older adults, and dietary patterns have an impact on cognitive function. However, no systematic researches have constructed anti-inflammatory diet (AID) and protein-enriched diet (PED) to explore their association with CI among older adults in China. METHODS: The data used in this study were obtained from the 2018 waves of the China Longitudinal Health and Longevity Survey (CLHLS). We construct AID, PED, and calculate scores for CI. We use binary logistic regression to explore the relationship between them, and use restrictive cubic splines to determine whether the relationships are non-linear. Subgroup analysis and sensitivity analysis were used to demonstrate the robustness of the results. RESULTS: A total of 8692 participants (mean age is 83.53 years) were included in the analysis. We found that participants with a higher AID (OR = 0.789, 95% confidence interval: 0.740-0.842, p < 0.001) and PED (OR = 0.910, 95% confidence interval: 0.866-0.956, p < 0.001) score showed lower odds of suffering from CI. Besides, the relationship between the two dietary patterns and CI is linear, and the results of subgroup analysis and sensitivity analysis are also significant. CONCLUSION: Higher intakes of AID and PED are associated with a lower risk of CI among older adults, which has important implications for future prevention and control of CI from a dietary and nutritional perspective.

Confidence intervals for odds ratio from multistage randomized phase II trials.

A multi-stage randomized trial design can significantly improve efficiency by allowing early termination of the trial when the experimental arm exhibits either low or high efficacy compared to the control arm during the study. However, proper inference methods are necessary because the underlying distribution of the target statistic changes due to the multi-stage structure. This article focuses on multi-stage randomized phase II trials with a dichotomous outcome, such as treatment response, and proposes exact conditional confidence intervals for the odds ratio. The usual single-stage confidence intervals are invalid when used in multi-stage trials. To address this issue, we propose a linear ordering of all possible outcomes. This ordering is conditioned on the total number of responders in each stage and utilizes the exact conditional distribution function of the outcomes. This approach enables the estimation of an exact confidence interval accounting for the multi-stage designs.

Estimation of the odds ratio from multi-stage randomized trials.

A multi-stage design for a randomized trial is to allow early termination of the study when the experimental arm is found to have low or high efficacy compared to the control during the study. In such a trial, an early stopping rule results in bias in the maximum likelihood estimator of the treatment effect. We consider multi-stage randomized trials on a dichotomous outcome, such as treatment response, and investigate the estimation of the odds ratio. Typically, randomized phase II cancer clinical trials have two-stage designs with small sample sizes, which makes the estimation of odds ratio more challenging. In this paper, we evaluate several existing estimation methods of odds ratio and propose bias-corrected estimators for randomized multi-stage trials, including randomized phase II cancer clinical trials. Through numerical studies, the proposed estimators are shown to have a smaller bias and a smaller mean squared error overall.

Evolutionary mining and functional characterization of TnpB nucleases identify efficient miniature genome editors.

As the evolutionary ancestor of Cas12 nuclease, the transposon (IS200/IS605)-encoded TnpB proteins act as compact RNA-guided DNA endonucleases. To explore their evolutionary diversity and potential as genome editors, we screened TnpBs from 64 annotated IS605 members and identified 25 active in Escherichia coli, of which three are active in human cells. Further characterization of these 25 TnpBs enables prediction of the transposon-associated motif (TAM) and the right-end element RNA (reRNA) directly from genomic sequences. We established a framework for annotating TnpB systems in prokaryotic genomes and applied it to identify 14 additional candidates. Among these, ISAam1 (369 amino acids (aa)) and ISYmu1 (382 aa) TnpBs demonstrated robust editing activity across dozens of genomic loci in human cells. Both RNA-guided genome editors demonstrated similar editing efficiency as SaCas9 (1,053 aa) while being substantially smaller. The enormous diversity of TnpBs holds potential for the discovery of additional valuable genome editors.

Characterisation of X chromosome status of human extended pluripotent stem cells.

Different pluripotent cell types have been established by capturing pluripotency in different states. Human extended pluripotent stem cells (hEPSCs), recently established by two independent studies, have the capability of differentiating into both embryonic and extraembryonic lineages, as well as forming human blastoids, showing great potential for early human development modeling and regenerative medicine. Considering that X chromosome status in female human pluripotent stem cells is dynamic and heterogeneous, and often leads to functional consequences, we characterized it in hEPSCs. We derived hEPSCs from primed human embryonic stem cells (hESCs) with defined X chromosome status (pre- or post-X chromosome inactivation) using two previously published methods. We showed that hEPSCs derived using both methods had highly similar transcription profiles and X chromosome status. However, the X chromosome status of hEPSCs is largely determined by the primed hESCs from which they were derived, suggesting a lack of complete reprogramming of X chromosome during primed to extended/expanded pluripotency conversion. Furthermore, we found that the X chromosome status of hEPSCs affected their ability to differentiate into embryonic or extraembryonic lineage cells. Taken together, our work characterized the X chromosome status of hEPSCs, providing important information for the future application of hEPSCs.

Production of medical isotope 68Ge based on a novel chromatography separation technique and assembling of 68Ge/68Ga generator.

A double-column chromatography separation technique was involved for isolation of 68Ge from a bombarded Ga-Ni alloy target. About 185 MBq 68Ge obtained was used for assembling SnO2-based 68Ge/68Ga generator. Approximately 70% of 68Ga in high radioactivity concentration was eluted from generator with excellent radionuclidic, radiochemical and chemical purity. 68Ga was quite adequate for radiolabeling with DOTATATE or PSMA-617 with a high labelling efficiency of >92%. The double-column chromatography technique possessed a potential application prospect of 68Ge/68Ga production, aiding the development of 68Ga in nuclear medicine.

Optimal designs for phase II clinical trials with heterogeneous patient populations.

We consider single-arm phase II cancer clinical trials with tumor response as the primary outcome. Oftentimes, the patient population of a phase II clinical trial consists of subpopulations with different expected response rates. A well-accepted design in this case is to specify the response rate and the prevalence of each subpopulation, to compute the response rate of the whole population using the weighted (by prevalence) average of the response rates across subpopulations, and to find a standard phase II design, such as Simon's minimax or optimal design, for testing on the response rate of the whole population based on the unstratified binomial test. In such trials, while the response rate is the primary parameter and the prevalence of each subpopulation is a nuisance parameter, the validity of an unstratified statistical test for deciding acceptance or rejection of the experimental treatment is influenced by observed prevalence. In order to avoid bias due to the discrepancy between observed and specified values of the nuisance parameter, we have to use stratified test for such trials. In this paper, we propose optimal and minimax designs for stratified binomial test. We also develop a user-friendly interactive software to visualize the optimal designs and help users make correct statistical decisions.

Neutrophils restrain sepsis associated coagulopathy via extracellular vesicles carrying superoxide dismutase 2 in a murine model of lipopolysaccharide induced sepsis.

Disseminated intravascular coagulation (DIC) is a complication of sepsis currently lacking effective therapeutic options. Excessive inflammatory responses are emerging triggers of coagulopathy during sepsis, but the interplay between the immune system and coagulation are not fully understood. Here we utilize a murine model of intraperitoneal lipopolysaccharide stimulation and show neutrophils in the circulation mitigate the occurrence of DIC, preventing subsequent septic death. We show circulating neutrophils release extracellular vesicles containing mitochondria, which contain superoxide dismutase 2 upon exposure to lipopolysaccharide. Extracellular superoxide dismutase 2 is necessary to induce neutrophils' antithrombotic function by preventing endothelial reactive oxygen species accumulation and alleviating endothelial dysfunction. Intervening endothelial reactive oxygen species accumulation by antioxidants significantly ameliorates disseminated intravascular coagulation improving survival in this murine model of lipopolysaccharide challenge. These findings reveal an interaction between neutrophils and vascular endothelium which critically regulate coagulation in a model of sepsis and may have potential implications for the management of disseminated intravascular coagulation.

Practicality of hierarchically macro/mesoporous γ-Al2O3 as a promising sorbent in the preparation of low specific activity 99Mo/99mTc generator.

Hierarchically macro-/mesoporous γ-Al2O3 (HMMA) was synthesized and characterized by various analytical techniques. The results indicated that HMMA possessed macropores (∼0.45 µm) and mesopores (∼10.6 nm) with a large surface area (∼542 m2 g-1). The absorption behaviors of Mo and Re with HMMA were investigated. The maximum static absorption capacity could reach about 250 mg Mo per g HMMA. The absorption equilibrium can be attained quickly within 10 mins. At initial Mo ions concertation of 10,000 mg L-1, the breakthrough capacity was determined to be around 200 mg Mo per g HMMA. Additional, absorption mechanism results indicated that Mo ions reacts strongly with a hydroxyl on the surface of γ-Al2O3 and an adjacent Al atom, simultaneously. A 9.15 mCi (339 MBq) 99Mo generator was prepared and evaluated its performance for over one week. The recovery of 99mTc could reach about 89% with favorable radionuclidic, radiochemical and chemical purity for nuclear medicine application. HMMA has a potential application prospect for the preparation of low specific activity (LSA) 99Mo/99mTc generator.

Nitrogen-doped nanoporous graphene induced by a multiple confinement strategy for membrane separation of rare earth.

Rare earth separation is still a major challenge in membrane science. Nitrogen-doped nanoporous graphene (NDNG) is a promising material for membrane separation, but it has not yet been tested for rare earth separation, and it is limited by multi-complex synthesis. Herein, we developed a one-step, facile, and scalable approach to synthesize NDNG with tunable pore size and controlled nitrogen content using confinement combustion. Nanoporous hydrotalcite from Zn(NO3)2 is formed between layers of graphene oxide (GO) absorbed with phenylalanine via confinement growth, thus preparing the sandwich hydrotalcite/phenylalanine/GO composites. Subsequently, area-confinement combustion of hydrotalcite nanopores is used to etch graphene nanopores, and the hydrotalcite interlayer as a closed flat nanoreactor induces two-dimensional space confinement doping of planar nitrogen into graphene. The membrane prepared by NDNG achieves separation of Sc3+ from the other rare earth ions with excellent selectivity (∼3.7) through selective electrostatic interactions of pyrrolic-N, and separation selectivity of ∼1.7 for Tm3+/Sm3+.

Construction of Position-Controllable Graphene Bubbles in Liquid Nitrogen with Assistance of Low-Power Laser.

Graphene bubbles (GBs) are of significant interest owing to their distinguished electrical, optical, and magnetic properties. GBs can also serve as high-pressure reaction vessels to numerous chemical reactions. However, previous strategies to produce GBs are relatively elaborate and random. Therefore, their potential applications are severely restricted. Here, a facile and effective protocol is proposed to construct position-controllable GBs in liquid nitrogen (LN) with the assistance of laser and graphene wrinkles. Specifically, a film of graphene mounted on a SiO2 substrate (G@SiO2) is subjected to irradiation by a low-power laser in LN and then many GBs emerge from the surface of G@SiO2. Most impressively, the domain where GBs arise is the position of the laser beam spot. Hence, we demonstrated that the high collimation of laser facilitates the position definition of GBs. The microscopic results indicate that some GBs split into three parts when they were subjected to irradiation by an electron. Meanwhile, some GBs degenerate into pores with a diameter of 500 nm when they are exposed to air. To grasp the properties of GBs in depth, the molecular dynamics (MD) simulations are performed, and the corresponding results indicate that temperature has very little impact on the GBs' shape. A phase transition process of the substance inside GBs is also revealed. Moreover, a two-dimensional (2D) solid nitrogen is discovered by MD simulations. The simplicity of our protocol paves the way to engineer high-pressure microreaction vessels and fabricate porous graphene membranes.

Overcoming Autocrine FGF Signaling-Induced Heterogeneity in Naive Human ESCs Enables Modeling of Random X Chromosome Inactivation.

Primed and naive human embryonic stem cells (hESCs) do not fully recapitulate the X chromosome status observed in human preimplantation epiblast and fail to initiate random X chromosome inactivation (XCI) upon differentiation. Therefore, an ideal system for studying XCI during early human development is yet to be established. We show that incomplete blocking of autocrine fibroblast growth factor 2 (FGF2) signaling in naive hESCs drives significant heterogeneity in X chromosome and pluripotency status. We derived homozygous XaXa naive hESCs with dual allelic XIST expression and high levels of TFCP2L1, whose transcriptome and X chromosome states are similar to human preimplantation epiblast. Random XCI was initiated upon naive-to-primed conversion of these cells, and both pre- and post-XCI primed hESCs were obtained. We observed random XCI in all cells upon further differentiation of pre-XCI primed hESCs. Together, these findings enable derivation of homogeneous naive hESCs and establish a powerful platform to study human XCI.

Influence of nanopore density on ethylene/acetylene separation by monolayer graphene.

The use of nanoporous graphene for separation has attracted increasing interest over the past few years. Nanopore size, temperature, pressure and functionalization are vital for selectivity, but the influence of nanopore density is not known. Thus, we designed a monolayer nanoporous graphene membrane and revealed the influence of nanopore density on its ethylene/acetylene separation performance by employing molecular dynamics (MD) simulations. Our results indicate that an optimal nanopore density exists for permeation flux and selectivity. The MD simulation results were confirmed by density functional theory (DFT) and the kinetic theory of gases. The interactions between ethylene/acetylene and nanopores were also investigated, and van der Waals (vdW) interactions with slight steric repulsion were detected.

The study of rhenium pentacarbonyl complexes using single-atom chemistry in the gas phase.

A gas-phase chemical study of rhenium carbonyls was carried out using short-lived radioisotopes produced at a heavy-ion accelerator. The Re isotopes produced in the nuclear reactions of natGd(23Na,xn)172-177Re were pre-separated with a gas-filled recoil ion separator and their carbonyls were synthesized in a mixture of inert gas and carbon monoxide. Using a low temperature isothermal chromatography apparatus, the adsorption enthalpies of Re carbonyls were derived to be ΔHads = -42 ± 2 kJ mol-1 on a Teflon® surface by fitting the external chromatograms with a Monte Carlo simulation program. A chemical yield of 25% relative to that of the transport yield for Re by a He/KCl gas-jet was achieved. The laser-ablation time-of-flight mass-spectrometric technique was employed to identify the species of Re carbonyls produced in the gas phase. The most stable species was deduced to be Re(CO)5 based on the mass-spectrometric analysis as well as quantum chemistry calculations.

Bacteria-free minicircle DNA system to generate integration-free CAR-T cells.

BACKGROUND: Chimeric antigen receptor T (CAR-T) cells engineered with lentiviral and retroviral vectors have been successfully applied to treat patients with B cell malignancy. However, viral integration in T cells has the potential risk of mutagenesis, and viral vector production demands effort and is costly. Using non-integrative episomal vector such as minicircle vector to generate integration-free CAR-T cells is an attractive option. METHODS AND RESULTS: We established a novel method to generate minicircle vector within a few hours using simple molecular biology techniques. Since no bacteria is involved, we named these vectors bacteria-free (BF) minicircle. In comparison with plasmids, BF minicircle vector enabled higher transgene expression and improved cell viability in human cell line, stem cells and primary T cells. Using BF minicircle vector, we generated integration-free CAR-T cells, which eliminated cancer cells efficiently both in vitro and in vivo. CONCLUSION: BF minicircle vector will be useful in basic research as well as in clinical applications such as CAR-T and gene therapy. Although the transgene expression of minicircle vector lasts apparently shorter than that of insertional lentivirus, multiple rounds of BF minicircle CAR-T cell infusion could eliminate cancer cells efficiently. On the other hand, a relatively shorter CAR-T cell persistence provides an opportunity to avoid serious side effects such as cytokine storm or on-target off-tumour toxicity.

Highly Efficient and Selective Dissolution Separation of Fission Products by an Ionic Liquid [Hbet][Tf2N]: A New Approach to Spent Nuclear Fuel Recycling.

Here, we propose the use of carboxyl-functionalized ionic liquid, [Hbet][Tf2N], to separate the fission products from spent nuclear fuels. This innovative method allows the selective dissolution of neutron poisons, lanthanides oxide, as well as some fission products with high yield, leaving most of the UO2 matrix and minor actinides behind in the spent nuclear fuel and accomplishing the actinides recovery as a group. Water-saturated [Hbet][Tf2N] can dissolve lanthanides oxide from simulated spent nuclear fuel with a dissolution ratio of 100% at 40 °C. However, the dissolution of uranium is almost negligible (<1%) under the same conditions. This big difference in dissolution provides a novel separation approach to spent nuclear fuel recycling and may open new perspectives for spent nuclear fuel reprocessing. The recovery of Nd and U from metal-loaded ionic liquids and the recyclability of the ionic liquid [Hbet][Tf2N] have also been investigated. Furthermore, a U/ x value related to the lattice energy U of metal compound M xO y is used to elaborate the solubility. This work represents the first case for efficient fission products removal by selective dissolution, avoiding the complete dissolution of spent nuclear fuel, the producing of the large high-level radioactive waste, and reducing environmental hazards.

Ultrahigh-photoresponsive UV photodetector based on a BP/ReS2 heterostructure p-n diode.

The van der Waals (vdW) heterostructure, made up of two dissimilar two-dimensional materials held together by van der Waals interactions, has excellent electronic and optoelectronic properties as it provides a superior interface quality without the lattice mismatch problem. Here, we report the development and photoresponse characteristics of a p-n diode based on a stacked black phosphorus (BP) and rhenium disulfide (ReS2) heterojunction. The heterojunction showed a clear gate-tunable rectifying behavior similar to that of the conventional p-n junction diode. Under UV illumination, the BP/ReS2 p-n diode displayed a high photoresponsivity of 4120 A W-1 and we were able to modify the photoresponse properties by adjusting the back gate voltage. Moreover, an investigation of various channel lengths yielded the highest photoresponsivity of 11 811 A W-1 for a BP length of 1 µm. These results suggested vdW 2D materials to be promising for developing advanced heterojunction devices for nano-optoelectronics.

Collisions of noble gas atoms with graphene and a graphene nanodome.

The collisions of noble gas atoms with graphene and a graphene nanodome were investigated by employing first principles molecular dynamics calculations. By analyzing the electron-related properties of the collision process, the atom dynamics and the deformation of the graphene/nanodome, our results show a difference between the elastic properties of the nanodome and graphene. Generally, the nanodome can more easily revert to its initial conformation. The final kinetic energy, Ef, of the atom that collides with the nanodome is larger than the Ef of the atom that collides with graphene. In addition, the relationship between the initial kinetic energy of the atom, Ek0, and its corresponding proportion of energy loss, χ, is linear (except for the Kr atom). Our research will probably contribute to the investigation of the 2D materials' mechanical properties and their surface morphology. Moreover, due to its novel mechanical properties, the graphene nanodome is an extraordinary nano-architecture which can be employed to protect nano-devices from damage and injury.

Hydrothermal synthesis of 4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb) phosphors: Morphology-tunable and luminescence properties.

4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb) phosphors with different morphologies have been successfully synthesized via one-step hydrothermal method through regulating the molar amount of Eu3+ and Tb3+. Comprehensive scanning electron microscopy (SEM), X-ray diffraction (XRD) Fourier transform infrared spectrum (FT-IR) and inductively coupled plasma atomic emission spectrometer (ICP-AES) characterizations all confirm that obtained products are 4ZnO·B2O3·H2O:Ln3+ (Ln=Eu, Tb). The experimental results displayed that the morphology and photoluminescence of compounds is regularly changed with increased the molar amount of rare earth ions. For the Eu3+-doped, Tb3+-doped and Eu3+/Tb3+ co-doped 4ZnO·B2O3·H2O phosphors of morphologies, the rod-like structures gradually changed to flower-like structures, fine wire-like structure and hybrid structure, respectively. To their photoluminescence, the Eu3+ shows a red emission (615nm); the Tb3+ shows a green emission (545nm); for the Eu3+/Tb3+ co-doped 4ZnO·B2O3·H2O phosphors, a combination of blue (5d-4f of Eu2+), green (5D4-7F5 of Tb3+) and red (5D0-7F2 of Eu3+) emissions emerges to achieve white emission. In addition, the energy transfer among Eu3+, Eu2+ and Tb3+ ions was also discussed.