Enhancing mechanical performance of green fiber cement composites:Role of eco-friendly alkyl ketene dimer on surfaces of hemp fibers

Fiber composites reinforced natural fibers have attracted more attention in sustainable building materials due to the high Young's modulus, availability, and biodegradability. However, poor interfacial bonding of the fiber-reinforced cement composites attributed to the intrinsically swelling-shrinkage behavior of the hydrophilic natural fibers, seriously limits the strength development of the composite. Here, an eco-friendly and low-cost surface treatment agent, alkyl ketene dimer (AKD), is innovatively introduced for reinforcing the combined effect of hemp fiber (HF)/cement matrix. The experimental approach includes the chemical modification of hemp fibers, followed by the direct preparation of fiber cement composites. Fourier transformation infrared spectroscopy (FTIR) and water absorption test analyses confirmed that the modified HF surface was successfully grafted with AKD, leading to superior hydrophobic characterization and reduced swelling-shrinking behavior. Adding the modified HF to the cement composites effectively enhanced their mechanical properties and toughness capacity by strengthening the interfacial bond of modified HF/Mortar. The modified fiber-reinforced mortar has the highest increment (28 % in compressive strength and 24 % in flexural strength, respectively) from 7 d to 28 d among all investigated mortars. Furthermore, the micro-observation of fractured mortar composites supports the strengthened interface of the modified fibers/cement matrix. The study provides a feasible and practical approach to improving the comprehensive strength properties of hemp fiber-reinforced cement composites. It benefits the practical industrial-scale application of biomaterials in low-cost housing, thus enhancing sustainability

A Class Age-Structured HIV/AIDS Model with Impulsive Drug-Treatment Strategy

We formulate an HIV/AIDS transmission model that considers the dependence of HIV/AIDS progress on infection age (the time since infection), disease age (the time elapsed since the onset), and impulsive antiretroviral treatment. Since no effective vaccine is available for HIV/AIDS, our impulsive disease-control strategy is targeted at infected individuals (I control). Thus the model only includes infective class and AIDS class: infected population is the state at birth, and AIDS population is not the state at birth. Assuming the theoretical strategy can provide HIV testing for risk population groups every years and immediate antiretroviral treatment for HIV-positive people. The action is approximated by impulsive differential equations. We demonstrate the effect of the impulsive drug treatment and show that there exists a globally stable infection-free state when the impulsive period and drug-treatment proportion satisfy (,)<1. This result shows that the prevention effects can drive HIV/AIDS epidemic towards to elimination

Improving the interface compatibility and mechanical performances of the cementitious composites by low-cost alkyl ketene dimer modified fibers

Natural fibers-reinforced cement composites have recently attracted more interest due to the trend in the development of sustainable construction materials. However, the poor fiber–matrix interface compatibility, which is caused by the swelling-shrinking behavior of hydrophilic natural fiber, negatively affects the mechanical properties of the composites thereby hindering their practical application. In order to promote interfacial compatibility, a new fiber surface treatment is needed. A low-cost alkyl ketene dimer (AKD) is adopted in this work, aiming at replacing the relatively expensive silane agents. This study focuses on fiber surface treatment and the resulting effects on the interface compatibility and mechanical performances of the composites. The effect of the fiber modification was characterized by FTIR and water absorption test; The interfacial compatibility of the composites was evaluated by the compatibility index calculation and SEM observation; A series of strength properties of the composites were carried out considering the influence of interface compatibility on mechanical performance. Results show a clear improvement in both interface compatibility and mechanical properties of the composites when AKD-modified fibers are used as reinforcement. The compressive and flexural strength are effectively increased up to 53 MPa and 8 MPa, respectively. Moreover, the approach of the low-cost AKD modification could further be applied to any natural fibers in cementitious composites, allowing cost-effectiveness in practical applications

Assessing the impacts of phosphorus inactive clay on phosphorus release control and phytoplankton community structure in eutrophic lakes

Addressing the challenge that phosphorus is the key factor and cause for eutrophication, we evaluated the phosphorus release control performance of a new phosphorus inactive clay (PIC) and compared with Phoslock(®). Meanwhile, the impacts of PIC and Phoslock(®) on phytoplankton abundance and community structure in eutrophic water were also discussed. With the dosage of 40 mg/L, PIC effectively removed 97.7% of total phosphorus (TP) and 98.3% of soluble reactive phosphorus (SRP) in eutrophic waters. In sediments, Fe/Al-phosphorus and organic phosphorus remained stable whereas Ca-phosphorus had a significant increase of 13.1%. The results indicated that PIC may form the active overlay at water-sediment interface and decrease the bioavailability of phosphorus. The phytoplankton abundance was significantly reduced by PIC and decreased from (1.0-2.4) × 10(7) cells/L to (1.3-4.3) × 10(6) cells/L after 15 d simultaneous experiment. The phytoplankton community structure was also altered, where Cyanobacteria and Bacillariophyceae were the most inhibited and less dominant due to their sensitivity to phosphorus. After PIC treatment, the residual lanthanum concentration in water was 1.44-3.79 μg/L, and the residual aluminium concentration was low as 101.26-103.72 μg/L, which was much less than the recommended concentration of 200 μg/L. This study suggests that PIC is an appropriate material for phosphorus inactivation and algal bloom control, meaning its huge potential application in eutrophication restoration and management

VAD: Vectorized Scene Representation for Efficient Autonomous Driving

Autonomous driving requires a comprehensive understanding of the surrounding environment for reliable trajectory planning. Previous works rely on dense rasterized scene representation (e.g., agent occupancy and semantic map) to perform planning, which is computationally intensive and misses the instance-level structure information. In this paper, we propose VAD, an end-to-end vectorized paradigm for autonomous driving, which models the driving scene as a fully vectorized representation. The proposed vectorized paradigm has two significant advantages. On one hand, VAD exploits the vectorized agent motion and map elements as explicit instance-level planning constraints which effectively improves planning safety. On the other hand, VAD runs much faster than previous end-to-end planning methods by getting rid of computation-intensive rasterized representation and hand-designed post-processing steps. VAD achieves state-of-the-art end-to-end planning performance on the nuScenes dataset, outperforming the previous best method by a large margin. Our base model, VAD-Base, greatly reduces the average collision rate by 29.0% and runs 2.5x faster. Besides, a lightweight variant, VAD-Tiny, greatly improves the inference speed (up to 9.3x) while achieving comparable planning performance. We believe the excellent performance and the high efficiency of VAD are critical for the real-world deployment of an autonomous driving system. Code and models will be released for facilitating future research.Comment: Code&Demos: https://github.com/hustvl/VA

An experimental study and axial tensile constitutive model of the toughness of PP-SACC for rapid repairs

To improve the economic benefits of engineered cementitious composites and control the repair cycle, repair materials were designed, with the key components of the mixture being low-cost polypropylene (PP) fibers and fast-setting sulfoaluminate cement. The effects of water/binder ratio, fiber content, and aggregate particle size on the flowability, mechanical properties, and toughness of the polypropylene fiber-reinforced sulfoaluminate cementitious composite (PP-SACC) were explored. Based on experimentally measured axial tensile stress–strain curves, a constitutive model of PP-SACC was derived in terms of fiber content and water/binder ratio. Additionally, the correlation coefficients representing the relationships of the mixture indices with the tensile properties were explored based on revised gray relational analysis. Test results indicated that fiber content and water/binder ratio were the most important factors affecting the mechanical properties, toughness, and fluidity of the material; in contrast, the influence of aggregate size was slight. The PP-SACC mixture with an aggregate size of 75 µm, a water/binder ratio of 0.30, and a fiber content of 3.0% demonstrated an excellent degree of toughness and exhibited a flexural hardening phenomenon under bending load

The Preexplosion Environments and the Progenitor of SN 2023ixf from the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX)

Supernova (SN) 2023ixf was discovered on 2023 May 19. The host galaxy, M101, was observed by the Hobby-Eberly Telescope Dark Energy Experiment collaboration over the period 2020 April 30-2020 July 10, using the Visible Integral-field Replicable Unit Spectrograph (3470 ≲ λ ≲ 5540 Å) on the 10 m Hobby-Eberly Telescope. The fiber filling factor within ±30″ of SN 2023ixf is 80% with a spatial resolution of 1″. The r < 5.″5 surroundings are 100% covered. This allows us to analyze the spatially resolved preexplosion local environments of SN 2023ixf with nebular emission lines. The two-dimensional maps of the extinction and the star formation rate (SFR) surface density (ΣSFR) show weak increasing trends in the radial distributions within the r < 5.″5 regions, suggesting lower values of extinction and SFR in the vicinity of the progenitor of SN 2023ixf. The median extinction and that of the surface density of SFR within r < 3″ are E(B − V) = 0.06 ± 0.14, and Σ SFR = 10 − 5.44 ± 0.66 M ☉ yr − 1 arcsec − 2 . There is no significant change in extinction before and after the explosion. The gas metallicity does not change significantly with the separation from SN 2023ixf. The metal-rich branch of the R 23 calculations indicates that the gas metallicity around SN 2023ixf is similar to the solar metallicity (∼Z ☉). The archival deep images from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) show a clear detection of the progenitor of SN 2023ixf in the z band at 22.778 ± 0.063 mag, but nondetections in the remaining four bands of CFHTLS (u, g, r, i). The results suggest a massive progenitor of ≈22 M

The Pre-explosion Environments and The Progenitor of SN 2023ixf from the Hobby Eberly Telescope Dark Energy Experiment (HETDEX)

Supernova (SN) 2023ixf was discovered on May 19th, 2023. The host galaxy, M101, was observed by the Hobby Eberly Telescope Dark Energy Experiment (HETDEX) collaboration over the period April 30, 2020 -- July 10, 2020, using the Visible Integral-field Replicable Unit Spectrograph (VIRUS; $3470\lesssim\lambda\lesssim5540$ \r{A}) on the 10-m Hobby-Eberly Telescope (HET). The fiber filling factor within $\pm$ 30 arcsec of SN 2023ixf is 80% with a spatial resolution of 1 arcsec. The r<5.5 arcsec surroundings are 100% covered. This allows us to analyze the spatially resolved pre-explosion local environments of SN 2023ixf with nebular emission lines. The 2-dimensional (2D) maps of the extinction and the star-formation rate (SFR) surface density ($\Sigma_{\rm SFR}$) show weak increasing trends in the radial distributions within the r<5.5 arcsec regions, suggesting lower values of extinction and SFR in the vicinity of the progenitor of SN 2023ixf. The median extinction and that of the surface density of SFR within r<3 arcsec are $E(B-V)=0.06\pm0.14$, and $\Sigma_{\rm SFR}=10^{-5.44\pm0.66}~\rm M_{\odot}\cdot yr^{-1}\cdot arcsec^{-2}$. There is no significant change in extinction before and after the explosion. The gas metallicity does not change significantly with the separation from SN 2023ixf. The metal-rich branch of the $R_{23}$ calculations indicates that the gas metallicity around SN 2023ixf is similar to the solar metallicity ($\sim Z_{\odot}$). The archival deep images from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) show a clear detection of the progenitor of SN 2023ixf in the $z$-band at $22.778\pm0.063$ mag, but non-detections in the remaining four bands of CFHTLS ($u,g,r,i$). The results suggest a massive progenitor of $\approx$ 22 $M_\odot$.Comment: 11 pages, 5 figures, Accepted by ApJ

Malignant glomus tumor of prostate: A case report

We reported an 85-year-old patient with malignant glomus tumor (GT) of the prostate. He presented with urinary frequency for more than 2 years and gross hematuria for 7 days. Computed tomography scan showed that the prostate was markedly irregularly enlarged, and the boundary between the prostate and the posterior wall of the bladder was unclear. Bilateral kidneys and ureters were dilated. Biochemical examinations showed that the serum potassium was 7.24 mmol/L and the serum creatinine was 974.6 μmol/L. Transurethral diagnostic resection was performed after restoring homeostasis through several times of bedside blood filtration. The pathological diagnosis was malignant GT. The patient’s renal function recovered after bilateral nephrostomy, and he refused further treatment and was out of contact after 9 months. We summarize the clinical and histopathological features of malignant GT of the prostate in order to improve the early recognition of the disease by clinicians