Monitoring MVOC Profiles over Time from Isolates of Aspergillus flavus Using SPME GC-MS

Fungi produce a variety of microbial volatile organic compounds (MVOCs) during primary and secondary metabolism. The fungus, Aspergillus flavus, is a human, animal and plant pathogen which produces aflatoxin, one of the most carcinogenic substances known. In this study, MVOCs were analyzed using solid phase microextraction (SPME) combined with GCMS from two genetically different A. flavus strains, an aflatoxigenic strain, NRRL 3357, and a non-aflatoxigenic strain, NRRL 21882. A PDMS/CAR SPME fiber was used over 30 days to observe variations in MVOCs over time. The relative percentage of individual chemicals in several chemical classes (alcohols, aldehydes, esters, furans, hydrocarbons, ketones, and organic acids) was shown to change considerably during the varied fungal growth stages. This changing chemical profile reduces the likelihood of finding a single chemical that can be used consistently as a biomarker for fungal strain identification. In our study, discriminant analysis techniques were successfully conducted using all identified and quantified MVOCs enabling discrimination of the two A. flavus strains over the entire 30-day period. This study underscores the potential of using SPME GCMS coupled with multivariate analysis for fungi strain identification.

Infrastructure Enhancement to Support Value-Added Bioproduct Recovery

The purpose of this research was to identify and make available new and existing information to facilitate more effective response by individuals, organizations, and government entities when storms and other forms of catastrophic disturbance lead to unplanned influxes of downed timber and woody debris across the southeastern United States. To this end, this project explored attitudes and behaviors of stakeholders regarding their post disaster timber salvage experiences. Findings are reported from twelve focus group sessions with forestry decision makers, including landowners, loggers, foresters, and agency representatives. Data were analyzed using an iterative coding process that organized large quantities of text into fewer categories and identified emergent themes. Relationships between themes and categories were described within and across cases based on their concurrence, antecedents, or consequences. This technique was followed by a content analysis focusing on discovering underlying meanings and understanding explicit versus euphemistic terms. Findings center around economic limitations and opportunities, social networks in resource utilization, and diverse interpretations of the disaster event. As well, findings demonstrate how risk perceptions and disaster experience interact to construct social meanings for disaster and associated preparedness activities. Implications include value-added utilization options for woody storm debris that have been pursued in past storm events and lessons learned that can inform future decisions.

Unraveling biochar surface area on structure and heavy metal removal performances of carbothermal reduced nanoscale zero-valent iron

Carbothermal reduction using biochar(BC)is a green and effective method of synthesizing BCsupported nanoscale zero-valent iron(nanoFe^(0))composites.However,the effect of BC surface area on the structure,distribution,and performance such as the heavy metal uptake capacity of nanoFe^(0)particles remains unclear.Soybean stover-based BCs with different surface areas(1.7−1472 m^(2)/g)were prepared in this study.They have been used for in-situ synthesis BCs-supported nanoFe^(0)particlesthrough carbothermal reduction of ferrous chloride.The BCs-supported nanoFe^(0)particles were found to be covered with graphene shells and dispersed onto BC surfaces,forming the BC-supported graphene-encapsulated nanoFe^(0)(BC-G@Fe^(0))composite.These graphene shells covering the nanoFe^(0)particles were formed because of gaseous carbon evolved from biomass carbonization reacting with iron oxides/iron salts.Increasing BC surface area decreased the average diameters of nanoFe^(0)particles,indicating a higher BC surface area alleviated the aggregation of nanoFe^(0)particles,which resulted in higher heavy metal uptake capacity.At the optimized condition,BC-G@Fe^(0)composite exhibited uptake capacities of 124.4,121.8,254.5,and 48.0 mg/g for Cu^(2+),Pb^(2+),Ag^(+),and As^(3+),respectively(pH 5,25℃).Moreover,the BC-G@Fe^(0)composite also demonstrated high stability for Cu^(2+)removal from the fixed-bed continuous flow,in which 1 g of BC-G@Fe^(0)can work for 120 h in a 4 mg/L Cu^(2+)flow continually and clean 28.6 L Cu^(2+)contaminated water.Furthermore,the BC-G@Fe^(0)composite can effectively immobilize the bioavailable As^(3+)from the contaminated soil,i.e.,5%(w)of BC-G@Fe^(0)composite addition can immobilize up to 92.2%bioavailable As^(3+)from the contaminated soil.

Synthesis, mechanical investigation, and application of nitrogen and phosphorus co-doped carbon dots with a high photoluminescent quantum yield

Heteroatom-doped carbon dots （CDs） with a high photoluminescent quantum yield （PLQY） have recently attracted attention due to their applications in chemical sensors, photocatalysis, bioimaging, and drug delivery. Nitrogen and phosphorus are in close proximity to carbon in the periodic table and are key tracking elements in the field of biomedical imaging. These two elements alter the optical and electronic properties of CDs and help improve the fundamental understanding of their PLQY. This can also lead to multifunctional usage in photoimaging and photothermal therapy. However, most PLQYs resulting from the synthesis of P-doped CDs are currently below 50%. These CDs have limited usefulness in the fields of bioimaging and drug delivery. In this study, a single-step, high-efficiency hydrothermal method was applied to synthesize nitrogen and phosphorous-doped carbon dots （（N,P）-CDs） with a PLQY of up to 53.8% with independent emission behavior. Moreover, the CDs presented high monodispersity, robust excitation-independent luminescence, and stability over a large pH range. Spectroscopic investigations indicated that the PLQY of the （N,P）-CDs was primarily due to the addition of P and the passivation effect of the oxidized surface. The excellent fluorescence properties of （N,P）-CDs can be effectively and selectively quenched by Hg2~ ions. Such systems show a linear response in the 0-900 nM concentration range with a short response time, indicating their potential for applications in the fields of chemistry and biology.

Pyrolytic synthesis of graphene-encapsulated zero-valent iron nanoparticles supported on biochar for heavy metal removal

Biochar(BC)-supported graphene-encapsulated zero-valent iron nanoparticle composites(BC-G@Fe0)are promising engineering nanocomposites that can be used to scavenge heavy metal from wastewater.However,the produc-tion of BC-G@Fe0 through carbothermal reduction using biomass as a carbon source remains challenging because of biomass pyrolysis complications.Here,we examined two carbothermal reduction routes for preparing BC-G@Fe0 using bamboo as the carbon source.The first route impregnated Fe ions(Fe^(2+)/^(3+))into unpyrolyzed bamboo parti-cles initially,followed by carbonization at 600-1000℃.This process produced BC-G@Fe0 dominated by iron carbide(Fe_(3)C),which led to low heavy metal removal efficiency(i.e.,Cu^(2+)capacity of<0.3 mmol g^(−1)).In the second route,bamboo particles were pyrolyzed(600℃)to biochar first,followed by impregnating this biochar with Fe ions,and then carbonized at 600-1000℃.This route produces zero-valent iron nanoparticles,which resulted in high heavy metal removal capacities(i.e.,0.30,1.58,and 1.91 mmol g^(−1)for Pb^(2+),Cu^(2+),and Ag+,respectively).The effects of car-bonization temperature(600-1000℃),iron source(i.e.,iron nitrates,iron sulfate,ferrous chloride,and ferric chloride),and iron loading(5-40%)on the morphology,structure,and heavy metal ion aqueous uptake performance of BC-G@Fe0 were also investigated.This study revealed the formation mechanisms of BC-G@Fe0 through biomass carbother-mal reduction,which could guide the application-oriented design of multifunctional iron-BC composites for water remediation.