The fast development of high-performance devices for diverse applications requires nanoscale materials with multifunctional properties, motivating theoretical exploration into novel two-dimensional (2D) materials. In this work, we propose a new family of 2D nanomaterials, Janus transition metal oxides and chalcogenides MXY (M = Ti, Zr, or Hf; X = S or Se; Y = O or S; X ≠ Y) monolayers, for their versatile applications. We find that the Janus MXY monolayers are semiconductors with a wide range of band gaps ranging from 0.739 to 2.884 eV. We show that TiSO, ZrSO, and HfSO monolayers are promising candidates for photocatalysis because of their suitable band gaps and optimal redox potentials for water splitting, and ZrSeS and HfSeS monolayers are suitable candidates for nanoscale electronics because of their high carrier mobility. We further show that TiSO, ZrSO, and ZrSeO monolayers possess large piezoelectric properties because of the broken inversion symmetry stemmed from the different atomic sizes and electronegativities of the X and Y elements, which are better or comparable to other 2D and bulk piezoelectric materials. Our study demonstrates that the 2D Janus MXYs may find versatile applications into photocatalysts, electronics, sensors, and energy harvesting/conversion.

BackgroundHuman papilloma virus (HPV) infection was the main cause of cervical cancer. There were only a few reports and detailed data about epidemiological research of HPV infection in rural population of China.Materials and MethodsThe cervical cells of rural Chaozhou women were collected, and multiplex real time PCR was firstly performed to detect high-risk HPV (HR-HPV) infection, which could detect 13 types of HR-HPV (types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, and 68). Then, HPV-positive samples were typed by HPV GenoArray test.ResultsHR-HPV DNA was detected by multiplex real time-PCR in 3830 of 48559 cases (7.89%). There was a peak incidence in age of 55–60 years group, and a lower incidence in who lived in plain group compared with suburban, mountain and seashore group. 3380 cases of HPV positive sample were genotyped, 11.01% (372/3380) cases could not be classified, among the typed 3008 cases, 101 cases were identified without HR-HPV type infection, 2907 cases were infected with one HR-HPV type at least, the 6 most common HR-HPV types in descending order of infection, were type 52 (33.4%, 16 (20.95%), 58 (15.93%), 33 (9.94%), 68 (9.22%) and 18 (8.36%). The combined prevalence of HPV types 16 and 18 accounted for 28.52% of total infection. However, type 52 plus 58 presented 48.23% of total infection. 2209/2907 cases were infected with a single HPV type and 698/2907 cases were infected with multiple types, and multiple infection constituent ratio increased with age, with a peak incidence in age 55–60 years group.ConclusionsOur findings showed low prevalence of HPV vaccine types (16 and 18) and relatively high prevalence of HPV-52 and -58, support the hypothesis that the second-generation HPV vaccines including HPV-52 and -58 may offer higher protection for women in rural Guangdong Province.

BackgroundTo establish the feasibility of the dosimetric compliance criteria of the RTOG 1308 trial through testing against Intensity Modulation Radiation Therapy (IMRT) and Passive Scattering Proton Therapy (PSPT) plans.MethodsTwenty-six lung IMRT and 26 proton PSPT plans were included in the study. Dose Volume Histograms (DVHs) for targets and normal structures were analyzed. The quality of IMRT plans was assessed using a knowledge-based engineering tool.ResultsMost of the RTOG 1308 dosimetric criteria were achieved. The deviation unacceptable rates were less than 10 % for most criteria; however, a deviation unacceptable rate of more than 20 % was computed for the planning target volume minimum dose compliance criterion. Dose parameters for the target volume were very close for the IMRT and PSPT plans. However, the PSPT plans led to lower dose values for normal structures. The dose parameters in which PSPT plans resulted in lower values than IMRT plans were: lung V5Gy (%) (34.4 in PSPT and 47.2 in IMRT); maximum spinal cord dose (31.7 Gy in PSPT and 43.5 Gy in IMRT); heart V5Gy (%) (19 in PSPT and 47 in IMRT); heart V30Gy (%) (11 in PSPT and 19 in IMRT); heart V45Gy (%) (7.8 in PSPT and 12.1 in IMRT); heart V50% (Gy) (7.1 in PSPT and 9.8 in IMRT) and mean heart dose (7.7 Gy in PSPT and 14.9 Gy in IMRT).ConclusionsThe revised RTOG 1308 dosimetric compliance criteria are feasible and achievable.

The size of film piece and analysis ROI used for calibration slightly affected the film response. Both transmission and reflection scanning modes can be used to analyze the Gafchromic XRQA2, with the reflection mode having a somewhat lower calibration uncertainty. Scanning films on alternate sides using transmission mode significantly affects the optical density. The film response was shown to be energy dependent. The films reached stability in about 6 h after exposure. The film response was proven to be independent of irradiation angle except when the beam is parallel to the film surface.

Active catalysts for nitrogen fixation (N2-fixation) have been widely pursued through constant efforts for industrial applications. Here, we report a family of catalysts, MXenes (M2X: M = Mo, Ta, Ti, and W; X = C and N), for application in N2-fixation based on density functional theory calculations. We find that the catalytic performance of MXenes strongly depends on the reaction energy in each reaction step. More exothermic steps lead to higher catalytic performance in the course of N2-fixation. We show that the reaction energy in N2-fixation is strongly affected by the charge transfer: (1) if N atoms gain more electrons in a step, the reaction is exothermic with a larger reaction energy; (2) if N atoms lose electrons in a step, the reaction is endothermic in general. We further show that Mo2C and W2C are highly active for N2-fixation due to their exothermic reactions and strong charge transfer, which may be applicable in the chemical-engineering industry.

Two dimensional (2D) nanomaterials have received increasing interest because of their unique properties for versatile applications.

The quality of radiation therapy depends on the ability to maximize the tumor control probability while minimize the normal tissue complication probability. Both of these two quantities are directly related to the accuracy of dose distributions calculated by treatment planning systems. The commonly used dose calculation algorithms in the treatment planning systems are reviewed in this work. The accuracy comparisons among these algorithms are illustrated by summarizing the highly cited research papers on this topic. Further, the correlation between the algorithms and tumor control probability/normal tissue complication probability values are manifested by several recent studies from different groups. All the cases demonstrate that dose calculation algorithms play a vital role in radiation therapy.

Tungsten disulfide (WS2) is a promising and low‐cost material for electrochemical hydrogen evolution reaction (HER) and has been extensively studied due to its excellent performance. However, the development of a facile and controllable defect‐engineering to activate its basal planes is still crucial to improve its HER activity. Here, we put forward an annealing strategy to create controllable sulfur vacancies (S‐vacancies) in ultrathin WS2 nanosheets, which can result in the increase of active sites and enhanced electrocatalytic activity accordingly. Our density‐functional‐theory (DFT) calculations reveal that the Gibbs free energy of hydrogen adsorption (ΔGH*) can be tuned to near zero by controlling the density of S‐vacancies, leading to thermal‐neutral HER performance. We find that optimal HER performance can be achieved by tuning the density of S‐vacancies in WS2 through annealing in the mixture of Ar and H2 (5 %). The WS2 nanosheets with the optimal density of S‐vacancies show lower overpotential by 116 mV at 10 mA/cm2 and smaller Tafel slope by 37.9 mV/dec than as‐prepared counterpart, and super‐excellent stability in acid. Additionally, the WS2 with optimal S‐vacancies also shows the best HER activity in alkaline solution. Our findings present a facile and general strategy to design electrocatalysts with more active sites, which is applicable to other materials for the improvement of their catalytic activities.