Laboratory and field evaluation of a low-cost optical particle sizer.

Low-cost sensors are widely used to collect high-spatial-resolution particulate matter data that traditional reference monitoring devices cannot. In addition to the mass concentration, the number concentration and size distribution are also fundamental in determining the origin and hazard level of particulate pollution. Therefore, low-cost optical sensors have been improved to establish optical particle sizers (OPSs). In this study, a low-cost OPS, the Nova SDS029, is introduced, and it is evaluated in comparison to two reference instruments-the GRIMM 11-D and the TSI 3330. We first tested the sizing accuracy using polystyrene latex spheres. Then, we assessed the mass and number size distribution accuracy in three application scenarios: indoor smoking, ambient air quality, and mobile monitoring. The evaluations suggest that the low-cost SDS029 rivals research-grade optical sizers in many aspects. For example, (1) the particle diameters obtained with the SDS029 are close to the reference instruments (usually < 10%) in the 0.3-5 µm range; (2) the number of particles and mass concentration are highly correlated (r ≥ 0.99) with the values obtained with the reference instruments; and (3) the SDS029 slightly underestimates the number concentration, but the derived PM2.5 values are closer to monitoring station than the reference instruments. The successful application of the SDS029 in multiple scenarios suggests that a plausible particle size distribution can be obtained in an easy and cost-efficient way. We believe that low-cost OPSs will increasingly be used to map the sources and risk levels of particles at the city scale.

Characterization of Antagonistic Bacillus methylotrophicus Isolated From Rhizosphere and Its Biocontrol Effects on Maize Stalk Rot.

Stalk rot is one of the most serious and widespread diseases in maize, and effective control measures are currently lacking. Therefore, this study aimed to develop a new biological agent to manage this disease. An antagonistic bacterial strain, TA-1, was isolated from rhizosphere soil and identified as Bacillus methylotrophicus based on morphological and biochemical characterization and 16S ribosomal RNA and gyrB gene sequence analyses. TA-1 exhibited a strong antifungal effect on the growth of Fusarium graminearum mycelium, with 86.3% inhibition at a concentration of 108 CFU per ml. Transmission electron microscopy showed that TA-1 could disrupt the cellular structure of the fungus, induce necrosis, and degrade the cell wall. Greenhouse and field trials were performed to evaluate the biocontrol efficacy of TA-1 on maize stalk rot, and the results of greenhouse experiment revealed that the bacterium significantly reduced disease incidence and disease index. Seeds treated with a 108 CFU ml-1 cell suspension had the highest disease suppression at 86.8%. Results of field trials show that seed bacterization with TA-1 could not only reduce maize stalk rot incidence but also increase maize height, stem diameter, and grain yield. The lipopeptide antibiotics were isolated from the culture supernatants of TA-1 and identified as surfactins and iturins. Consequently, B. methylotrophicus TA-1 is a potential biocontrol agent against maize stalk rot.

Clinical effect of hydrocolloid dressings in prevention and treatment of infant diaper rash.

The aim of the study was to investigate the application of hydrocolloid dressings in the prevention and treatment of infant diaper rash. A total of 210 infants with diaper rash were included in the study and randomized into 3 groups of 70 infants. Infants in group A received hydrocolloid dressings and individualized nursing; infants in group B received mupirocin plaster and topical application of pearl powder as well as routine nursing; and infants in group C received zinc oxide plaster and routine nursing. The clinical efficacy, incidence of adverse events, time to resolution of diaper rash, hospitalization duration, mean cost and satisfaction of nursing were compared between the 3 groups. After 1 cycle of treatment and nursing, the difference in the healing rate of mild diaper rash between groups A, B and C was significant (P<0.05), with the best healing rate in group A. Differences in the healing rate of grade I and II diaper rash between groups A, B and C was significant (P<0.05), with the best healing rate in group A. The incidence of adverse events in infants between groups A, B and C were significantly different (P<0.05), with the lowest incidence in group A (2.9%). The time to resolution of diaper rash, hospitalization duration and cost in infants were not significantly different (P<0.05). The satisfaction rate of nursing for the parents of groups A, B and C was 98.6, 87.1 and 80.0%, respectively (P<0.05). Hydrocolloid dressings combined with individualized nursing may prevent and treat infant diaper rash effectively, decrease the incidence of adverse reactions significantly, shorten time to resolution of diaper rash and hospitalization duration, reduce mean hospitalization cost, improve parent satisfaction and promote nursing-patient harmony. Thus, this method of treatment was worthy of clinical application.