Solidification/Stabilization of Arsenic-Containing Tailings by Steel Slag-Based Binders with High Efficiency and Low Carbon Footprint

The disposal of nonferrous metal tailings poses a global economic and environmental problem. After employing a clinker-free steel slag-based binder (SSB) for the solidification/stabilization (S/S) of arsenic-containing tailings (AT), the effectiveness, leaching risk, and leaching mechanism of the SSB S/S treated AT (SST) were investigated via the Chinese leaching tests HJ/T299-2007 and HJ557-2010 and the leaching tests series of the multi-process Leaching Environmental Assessment Framework (LEAF). The test results were compared with those of ordinary Portland cement S/S treated AT (PST) and showed that the arsenic (As) curing rates for SST and PST samples were in the range of 96.80–98.89% and 99.52–99.2%, respectively, whereby the leached-As concentration was strongly dependent on the pH of the leachate. The LEAF test results showed that the liquid–solid partitioning limit of As leaching from AT, SST, and PST was controlled by solubility, and the highest concentrations of leached As were 7.56, 0.34, and 0.33 mg/L, respectively. The As leaching mechanism of monolithic SST was controlled by diffusion, and the mean observed diffusion coefficient of 9.35 × 10−15 cm2/s was higher than that of PST (1.55 × 10−16 cm2/s). The findings of this study could facilitate the utilization of SSB in S/S processes, replacing cement to reduce CO2 emissions.

First Report of Leaf Blight Caused by Nigrospora oryzae on Poplar in China

Populus alba L. × P. berolinensis Dipp. (a hybrid poplar, ‘PaPb poplar’) exhibits fast growth and beautiful tree shape with high drought and cold tolerance, and is widely planted in the cities of Northeast China because of its ornamental and ecological value (Wang et al. 2008). In October 2020, an unknown leaf blight symptom was observed on the seedlings of ‘PaPb poplar’ at Shenyang Agricultural University (41°49′N, 123°34′E) located in Shenyang City, Liaoning Province, China. The disease incidence was 50% in a survey of 200 seedlings on the campus. The typical symptoms were brown-to-black, irregular-shaped lesions (Fig. 1A). To investigate the disease, five symptomatic leaves were collected, and pieces were cut at the margin of diseased and healthy tissue. These pieces were surface sterilized with 2% sodium hypochlorite for 2 min, rinsed three times with sterile distilled water, air dried, placed on potato dextrose agar (PDA) and incubated at 28°C. After 5 days of incubation, three isolates with similar morphological characteristics were observed. Isolate N03 was chosen and used for pathogen identification. The fungal colonies were initially white in color, and later turned gray to black (Fig. 1D). Conidia were single-celled, black, spherical or oblate in shape measuring 9.19 to 12.78 μm × 12.61 to 14.81 μm in diameter (n=40) (Fig. 1E). These were borne on hyaline vesicles at the tip of a conidiophore. Morphologically, the isolate N03 was identified as Nigrospora oryzae (Berk. and Broome) Petch (Wang et al. 2017). The genomic DNA was extracted with a SP Fungal DNA Kit (D5542-01, OMEGA). The internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (TEF1-α), and partial beta-tubulin (TUB) genes were amplified using the primers ITS5/ITS4 (White et al. 1990), EF1-728F/EF-2R (Carbone and Kohn, 1999; O’Donnell et al. 1998), and Bt-2a/Bt-2b (Glass and Donaldson, 1995) primer sets, respectively. The PCR products of ITS, TEF1-α, and TUB were amplified, sequenced, and deposited in GenBank with the following accession numbers MZ148528, MZ182080, and MZ182079, respectively. BLASTn analysis of the ITS, TEF1-α, and TUB sequences had 99.3%, 99.8%, and 99.27% nucleotide identities to MK131325, KY019328, and KY019559, respectively. A phylogenetic tree based on combined ITS, TEF1-α, and TUB sequences was constructed using a Maximum Likelihood method with 1000 bootstraps showing that N03 was grouped with other N. oryzae isolates (Fig. 2). The fungus was identified as N. oryzae based on morphological characteristics and molecular analyses. Koch’s postulates were completed to confirm the pathogenity of N. oryzae on ‘PaPb poplar’. The N03 spore suspension (105 spores/mL) was used to inoculate detached leaves and field leaves in two experiments. The two experiments were repeated three times, respectively. In the detached leaf test, 10 healthy leaves collected from 1-year-old ‘PaPb poplar’ seedlings were inoculated with N03 by spraying with the spore suspension followed by incubation at 28°C on wet filter papers in a petri dish for 7 days. 10 leaves were sprayed with sterile water to save as the controls. For field leaf test, leaves of 5 plants were spray-inoculated with the spore suspension at the 4-week-old growth stage, and an additional 5 plants were sprayed with sterile water. Seven days after inoculation, brown-to-black, irregular-shaped lesions on the margin of leaves were observed on inoculated leaves but not on the controls (Fig. 1B and C). All detached leaves inoculated with N03 were symptomatic. In the field tests, symptom appeared on 20 of the 30 inoculated leaves. N. oryzae was re-isolated from all the inoculated detached leaves and inoculated plants, but not from the controls. N. oryzae is a known pathogen of several hosts, such as Costus speciosus (Koen.) Sm. and Mentha spicata L., but has not been reported on any species of Populus. To our knowledge, this is the first report of leaf blight of ‘PaPb poplar’ caused by N. oryzae in China and the world. This disease could affect growth and development of ‘PaPb poplar’ seedlings, and may cause economic losses in the future. Appropriate strategies should be developed to manage this disease.

Identifikasi Jenis Bambu Berdasarkan Tekstur Daun dengan Metode Gray Level Co-Occurrence Matrix dan Gray Level Run Length Matrix

Bamboo species can be identified from the bamboo leaf images. This study conducted the identification of bamboo species based on leaf texture using Gray Level Co-occurrence Matrix (GLCM) and Gray Level Run Length Matrix (GLRLM) for texture feature extraction, and Euclidean distance for measure the image distance. This study used the images of bamboo species in Bengkulu province, that are bambusa Vulgaris Var Vulgaris, bambusa Multiplex, bambusa Vulgaris Var Striata, Gigantochloa Robusta, Gigantochloa Schortrchinii, Gigantochloa Serik, Schizostachyum Brachycladum, and Dendrocalamus Asper. The bamboo application was built using Matlab. The accuracy of the application was 100% for bamboo leaf test images captured using a smartphone camera and 81.25% for test images downloaded from the Internet.

Herb Leaves Recognition using Gray Level Co-occurrence Matrix and Five Distance-based Similarity Measures

Herb medicinal products derived from plants have long been considered as an alternative option for treating various diseases. In this paper, the feature extraction method used is Gray Level Co-occurrence Matrix (GLCM), while for its recognition using the metric calculations of Chebyshev, Cityblock, Minkowski, Canberra, and Euclidean distances. The method of determining the GLCM Analysis based on the texture analysis resulting from the extraction of this feature is Angular Second Moment, Contrast, Inverse Different Moment, Entropy as well as its Correlation. The recognition system used 10 leaf test images with GLCM method and Canberra distance resulted in the highest accuracy of 92.00%. While the use of 20 and 30 test data resulted in a recognition rate of 50.67% and 60.00%.

Beta-lactamase detection in Staphylococcus aureus and coagulase-negative Staphylococcus isolated from bovine mastitis

The objectives of the study were to evaluate the presence/production of beta-lactamases by both phenotypic and genotypic methods, verify whether results are dependent of bacteria type (Staphylococcus aureus versus coagulase-negative Staphylococcus - CNS) and verify the agreement between tests. A total of 200 bacteria samples from 21 different herds were enrolled, being 100 CNS and 100 S. aureus. Beta-lactamase presence/detection was performed by different tests (PCR, clover leaf test - CLT, Nitrocefin disk, and in vitro resistance to penicillin). Results of all tests were not dependent of bacteria type (CNS or S. aureus). Several S. aureus beta-lactamase producing isolates were from the same herd. Phenotypic tests excluding in vitro resistance to penicillin showed a strong association measured by the kappa coefficient for both bacteria species. Nitrocefin and CLT are more reliable tests for detecting beta-lactamase production in staphylococci.

Evaluation of Chemical Agents for the Control of Phytophthora ramorum and Other Species of Phytophthora on Nursery Crops

Phytophthora diseases occur frequently in nurseries, and the recent incidence of ramorum blight, caused by P. ramorum, on nursery crops has underscored the need for improved management strategies against all Phytophthora diseases. We evaluated several chemicals that target Oomycete pathogens, inoculating detached rhododendron or lilac leaves removed from plants previously treated with various chemicals, or chemically-treated leaves on intact plants. Results indicated that Subdue MAXX (drench or foliar application) was the most effective chemical in suppressing infections caused by all species of Phytophthora tested (P. ramorum, P. citricola, P. citrophthora, and P. nicotianae) except P. citrophthora; with P. ramorum, it was active for at least 6 weeks after spray application. More chemicals were effective when sporangial rather than mycelial plug inoculum of P. ramorum was used, including Aliette, Ranman, Stature DM, and Fenamidone. All chemicals tested were fungistatic, not fungicidal. These tests indicate that several materials inhibit infection by Phytophthora species, and that the detached leaf test is effective in evaluating efficacy of chemical agents for the suppression of Phytophthora pathogens from nurseries. Accepted for publication 10 November 2007. Published 11 February 2008.