Negatively charged nitrogen-vacancy (NV−) center ensembles in diamond have proved to have great potential for use in highly sensitive, small-package solid-state quantum sensors. One way to improve sensitivity is to produce a high-density NV− center ensemble on a large scale with a long coherence lifetime. In this work, the NV− center ensemble is prepared in type-Ib diamond using high energy electron irradiation and annealing, and the transverse relaxation time of the ensemble—T2—was systematically investigated as a function of the irradiation electron dose and annealing time. Dynamical decoupling sequences were used to characterize T2. To overcome the problem of low signal-to-noise ratio in T2 measurement, a coupled strip lines waveguide was used to synchronously manipulate NV− centers along three directions to improve fluorescence signal contrast. Finally, NV− center ensembles with a high concentration of roughly 1015 mm−3 were manipulated within a ~10 µs coherence time. By applying a multi-coupled strip-lines waveguide to improve the effective volume of the diamond, a sub-femtotesla sensitivity for AC field magnetometry can be achieved. The long-coherence high-density large-scale NV− center ensemble in diamond means that types of room-temperature micro-sized solid-state quantum sensors with ultra-high sensitivity can be further developed in the near future.

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Negatively charged nitrogen vacancy (NV−) centers in diamond have been extensively studied as high-sensitivity magnetometers, showcasing a wide range of applications. This study experimentally demonstrates a vector magnetometry scheme based on synchronous manipulation of NV− center ensembles in all crystal directions using double frequency microwaves (MWs) and multi-coupled-strip-lines (mCSL) waveguide. The application of the mCSL waveguide ensures a high degree of synchrony (99%) for manipulating NV− centers in multiple orientations in a large volume. Manipulation with double frequency MWs makes NV− centers of all four crystal directions involved, and additionally leads to an enhancement of the manipulation field. In this work, by monitoring the changes in the slope of the resonance line consisting of multi-axes NV− centers, measurement of the direction of the external field vector was demonstrated with a sensitivity of . Based on the scheme, the fluorescence signal contrast was improved by four times higher and the sensitivity to the magnetic field strength was improved by two times. The method provides a more practical way of achieving vector sensors based on NV− center ensembles in diamond.

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Human immunodeficiency virus type 1 (HIV-1) infection remains a severe public health problem worldwide. In this study, we investigated the distribution of HIV-1 subtypes and the prevalence of drug resistance mutations (DRMs) among patients with HIV-1 infection in Henan Province, China. HIV-1 strains in blood samples taken from inpatients and outpatients visiting the Sixth People's Hospital of Zhengzhou from August 2017 to July 2019 with a viral load (VL) greater than 1000 copies/ ml were subjected to subtype and DRMs analysis. Out of a total of 769 samples, subtype and DRM data were obtained from 657 (85.43%) samples. Phylogenetic analysis based on partial pol gene sequences indicated that the most commonly found genotype was subtype B (45.51%, 299/657), followed by CRF01_AE (28.61%, 188/657), CRF07_BC (15.68%, 103/657), CRF08_BC (0.76%, 5/657), C (0.61%, 4/657), A (0.30%, 2/657), and others (8.52%, 56/657). Circulating recombinant forms (CRFs) were most commonly found in patients who were naïve to antiretroviral treatment (ART) (68.67%, 160/233). The percentage of patients with one or more major drug-resistance mutations was 50.99% (335/657), and it was 6.44% (15/233) in ART-naive patients that were primarily infected with subtype B (17.74%). Resistance mutations were most common at codons 65, 103, 106, 184, and 190 of the reverse transcriptase gene and codon 46 of the protease gene. Our study provides detailed information about the distribution of HIV-1 subtypes and the incidence of drug resistance mutations of different subtypes in ART-experienced and naïve patients. This can guide policymakers in making decisions about treatment strategies against HIV-1.

Both CNT and NCNT catalysts presented marked deactivation after activating PMS. Moreover, the initial activities of deactivated CNT and NCNT were restored by thermal treatment at different temperatures (T-350, T-550 and T-750) and chemical reduction (R–NaBH4).

High-Q resonators with a large uniform field are widely used in magnetic imaging, but the microwave (MW) frequency shifts differently because of the near-field coupling. In this study, the major factors influencing of the frequency shifts were analyzed in a confocal system with nitrogen vacancy centers. We demonstrated a frequency calibration method involving adjustments of the applied magnetic field. This technique maintained the uniformity of the MW field with robustness to system noise, without changing the MW power. The effective imaging region reached 1.3 × 1.3 mm2 with a uniformity of 92.7%. This method preserves the stable operation of spin ensembles in magnetic imaging systems.