Removal of Aqueous Uranyl and Arsenate Mixtures after Reaction with Limestone, PO43-, and Ca2.

The co-occurrence of uranyl and arsenate in contaminated water caused by natural processes and mining is a concern for impacted communities, including in Native American lands in the U.S. Southwest. We investigated the simultaneous removal of aqueous uranyl and arsenate after the reaction with limestone and precipitated hydroxyapatite (HAp, Ca10(PO4)6(OH)2). In benchtop experiments with an initial pH of 3.0 and initial concentrations of 1 mM U and As, uranyl and arsenate coprecipitated in the presence of 1 g L-1 limestone. However, related experiments initiated under circumneutral pH conditions showed that uranyl and arsenate remained soluble. Upon addition of 1 mM PO43- and 3 mM Ca2+ in solution (initial concentration of 0.05 mM U and As) resulted in the rapid removal of over 97% of U via Ca-U-P precipitation. In experiments with 2 mM PO43- and 10 mM Ca2+ at pH rising from 7.0 to 11.0, aqueous concentrations of As decreased (between 30 and 98%) circa pH 9. HAp precipitation in solids was confirmed by powder X-ray diffraction and scanning electron microscopy/energy dispersive X-ray. Electron microprobe analysis indicated U was coprecipitated with Ca and P, while As was mainly immobilized through HAp adsorption. The results indicate that natural materials, such as HAp and limestone, can effectively remove uranyl and arsenate mixtures.

Study on the Antioxidant and Anticancer Activities of Sorbus pohuashanensis (Hance) Hedl Flavonoids In Vitro and Its Screen of Small Molecule Active Components.

Firstly, the antioxidant capacity of total flavonoids that was extracted from Sorbus pohuashanensis (Hance) Hedl was determined by ABTS+·radical-scavenging method, and MTT assay was used to mensurate the anti-tumor activity of total flavonoids In Vitro. Subsequently, the extraction conditions of flavonoids were optimized by the response surface methodology, the antioxidant activity was investigated simultaneously. Furthermore, the anti-tumor activity mechanism of flavonoids was simulated by molecular docking software. The antioxidant activity of flavonoids was correlated with the content in the process of optimizing the extraction condition. Moreover, The MTT assay revealed that SPF inhibited the activity of four sorts of cancer cells and positively correlated with the concentration of total flavonoids. And the experimental data demonstrated its anticancer activity was better at high concentrations. Finally, its anti-tumor activity was found that may be related to small molecules from flavonoids bind the apoptotic proteins Caspase-3, Caspase-8, and Caspase-9. The study could provide a theoretical basis for further pharmacodynamic research of Sorbus pohuashanensis (Hance) Hedl flavonoids, and improved a valuable attribute to Sorbus pohuashanensis (Hance) Hedl.

Human attention-inspired volume reconstruction method on serial section electron microscopy images.

The alignment of a 2D microscopic image stack to create a 3D image volume is an indispensable aspect of serial section electron microscopy (EM) technology, which could restore the original 3D integrity of biological tissues destroyed by chemical fixation and physical dissection. However, due to the similar texture intrasection and complex variations intersections of neural images, previous registration methods usually failed to yield reliable correspondences. And this also led to misalignment and impeded restoring the z-axis anatomical continuity of the neuron volume. In this article, inspired by human behaviors in finding correspondences, which use the topological relationship of image contents, we developed a spatial attention-based registration method for serial EM images to improve registration accuracy. Our approach combined the U-Net framework with spatial transformer networks (STN) to regress corresponding transformation maps in an unsupervised training fashion. The spatial attention (SA) module was incorporated into the U-Net architecture to increase the distinctiveness of image features by modeling its topological relationship. Experiments are conducted on both simulated and real data sets (MAS and RegCremi). Quantitative and qualitative comparisons demonstrate that our approach results in state of art accuracy (using the evaluation index of NCC, SSIM, Dice, Landmark error) and providing smooth and reliable transformation with less texture blur and unclear boundary than existing techniques. Our method is able to restore image stacks for visualization and quantitative analysis of EM image sequences.

Graphene oxide conjugated with polymers: a study of culture condition to determine whether a bacterial growth stimulant or an antimicrobial agent?

BACKGROUND: The results showed that the deciding factor is the culture medium in which the bacteria and the graphene oxide (GO) are incubated at the initial manipulation step. These findings allow better use of GO and GO-based materials more and be able to clearly apply them in the field of biomedical nanotechnology. RESULTS: To study the use of GO sheets applied in the field of biomedical nanotechnology, this study determines whether GO-based materials [GO, GO-polyoxyalkyleneamine (POAA), and GO-chitosan] stimulate or inhibit bacterial growth in detail. It is found that it depends on whether the bacteria and GO-based materials are incubated with a nutrient at the initial step. This is a critical factor for the fortune of bacteria. GO stimulates bacterial growth and microbial proliferation for Gram-negative and Gram-positive bacteria and might also provide augmented surface attachment for both types of bacteria. When an external barrier that is composed of GO-based materials forms around the surface of the bacteria, it suppresses nutrients that are essential to microbial growth and simultaneously produces oxidative stress, which causes bacteria to die, regardless of whether they have an outer-membrane-Gram-negative-bacteria or lack an outer-membrane-Gram-positive-bacteria, even for high concentrations of biocompatible GO-POAA. The results also show that these GO-based materials are capable of inducing reactive oxygen species (ROS)-dependent oxidative stress on bacteria. Besides, GO-based materials may act as a biofilm, so it is hypothesized that they suppress the toxicity of low-dose chitosan. CONCLUSION: Graphene oxide is not an antimicrobial material but it is a general growth enhancer that can act as a biofilm to enhance bacterial attachment and proliferation. However, GO-based materials are capable of inducing ROS-dependent oxidative stress on bacteria. The applications of GO-based materials can clearly be used in antimicrobial surface coatings, surface-attached stem cells for orthopedics, antifouling for biocides and microbial fuel cells and microbial electro-synthesis.

Rice bran feruloylated oligosaccharides activate dendritic cells via Toll-like receptor 2 and 4 signaling.

This work presents the effects of feruloylated oligosaccharides (FOs) of rice bran on murine bone marrow-derived dendritic cells (BMDCs) and the potential pathway through which the effects are mediated. We found that FOs induced phenotypic maturation of DCs, as shown by the increased expression of CD40, CD80/CD86 and MHC-I/II molecules. FOs efficiently induced maturation of DCs generated from C3H/HeN or C57BL/6 mice with normal toll-like receptor 4 (TLR-4) or TLR-2 but not DCs from mice with mutated TLR4 or TLR2. The mechanism of action of FOs may be mediated by increased phosphorylation of ERK, p38 and JNK mitogen-activated protein kinase (MAPKs) and increased NF-kB activity, which are important signaling molecules downstream of TLR-4 and TLR-2. These data suggest that FOs induce DCs maturation through TLR-4 and/or TLR-2 and that FOs might have potential efficacy against tumor or virus infection or represent a candidate-adjuvant approach for application in immunotherapy and vaccination.

Degradation of chlorinated solvents with reactive iron minerals in subsurface sediments from redox transition zones.

Reactive iron (Fe) mineral coatings found in subsurface reduction-oxidation transition zones (RTZs) contribute to the attenuation of contaminants. An 18.3-m anoxic core was collected from the site, where constituents of concern (COCs) in groundwater included chlorinated solvents. Reactive Fe mineral coatings were found to be abundant in the RTZs. This research focused on evaluating reaction kinetics with anoxic sediments bearing ferrous mineral nano-coatings spiked with either tetrachloroethylene (PCE), trichloroethylene (TCE), or 1,4-dichlorobenzene (1,4-DCB). Reaction kinetics with RTZ sediments followed pseudo-first-order reactions for the three contaminants with 90% degradation achieved in less than 39 days. The second-order rate constants for the three COCs ranged from 6.20 × 10-4 to 1.73 × 10-3 Lg-1h-1 with pyrite (FeS2), 4.97 × 10-5 to 1.24 × 10-3 Lg-1h-1with mackinawite (FeS), 1.25 × 10-4 to 1.89 × 10-4 Lg-1h-1 with siderite (FeCO3), and 1.79 × 10-4 to 1.10 × 10-3 Lg-1h-1 with magnetite (Fe3O4). For these three chlorinated solvents, the trend for the rate constants followed: Fe(II) sulfide minerals > magnetite > siderite. The high reactivity of Fe mineral coatings is hypothesized to be due to the large surface areas of the nano-mineral coatings. As a result, these surfaces are expected to play an important role in the attenuation of chlorinated solvents in contaminated subsurface environments.

[Hand-assisted laparoscopic surgery in radical resection of rectal cancer].

OBJECTIVE: To investigate the application experience and clinical effects of hand-assisted laparoscopic radical resection for rectal cancer. METHODS: The clinical data of 156 patients with rectal cancer treated with hand-assisted laparoscopic surgery between August 2009 and April 2011 were analyzed retrospectively. RESULTS: The operative procedures of 156 patients were completed successfully and 1 case was converted to laparotomy (0.6%). The mean operation time was (125 ± 35) minutes; the mean intraoperative blood loss was (118 ± 60) ml; the mean time of bowel function recovery was (60 ± 8) hours; the median postoperative hospital stay was (9.5 ± 2.2) days. The mean number of lymph nodes dissection was (14 ± 5). Five patients (3.2%) had postoperative complications. All the patients were followed up. There had been no local recurrence or trocar site implantation metastasis. CONCLUSION: Hand-assisted laparoscopic surgery approach for the curative resection of rectal cancer is safe and effective and has broad prospects in clinical application.

Fertility decline in rural China: a comparative analysis.

Many models have been proposed to explain both the rapidity of China's fertility decline after the 1960s and the differential timing of the decline in different places. In particular, scholars argue over whether deliberate policies of fertility control, institutional changes, or general modernization factors contribute most to changes in fertility behavior. Here the authors adopt an ethnographically grounded behavioral-institutional approach to analyze qualitative and quantitative data from three different rural settings: Xiaoshan County in Zhejiang (East China), Ci County in Hebei, (North China), and Yingde County in Guangdong (South China). The authors show that no one set of factors explain differential timing by a combination of differences in social-cultural environments (e.g. spread of education, reproductive ideologies, and gender relations) and politico-economic conditions (e.g. economic development, birth planning campaigns, and collective systems of labor organization) during the early phases of the fertility decline.

Identifying redox transition zones in the subsurface of a site with historical contamination.

Reactive iron mineral coatings found throughout reduction-oxidation (redox) transition zones play an important role in contaminant transformation processes. This research focuses on demonstrating a process for effectively delineating redox transition zones at a site with historical contamination. An 18.3 meter core was collected, subsampled, and preserved under anoxic conditions to maintain its original redox status. To ensure a high vertical resolution, sampling increments of 5.08 cm in length were analyzed for elemental concentrations with X-ray fluorescence (XRF), sediment pH, sediment oxidation-reduction potential (ORP), total volatile organic carbon (TVOC) concentration in the sample headspace, and abundant bacteria (16S rRNA sequencing). Over the core's length, gradients observed ranged from 3.74 to 8.03 for sediment pH, -141.4 mV to +651.0 mV for sediment ORP, and from below detection to a maximum of 9.6 ppm TVOC concentration (as chlorobenzene) in the headspace. The Fe and S gradients correlated with the presence of Fe and S reducing bacteria. S concentrations peaked in the Upper Zone and Zone 1 where Desulfosporosinus was abundant, suggesting precipitation of iron sulfide minerals. In Zone 2, Fe concentrations decreased where Geobacter was abundant, potentially resulting in Fe reduction, dissolution, and precipitation of minerals with increased solubility compared to the Fe(III) minerals. Using complementary geochemical and microbial data, five redox transition zones were delineated in the core collected. This research demonstrates a systematic approach to characterizing redox transition zones in a contaminated environment.

Roles of reactive iron mineral coatings in natural attenuation in redox transition zones preserved from a site with historical contamination.

In this study, a protocol was developed to identify reduction-oxidation (redox) transition zones in an effort to exploit natural source zone depletion processes. A sediment core with a total length of 18-m was collected from a site with historical contamination that includes chlorinated benzenes where the redox condition was preserved. In the four redox transition zones investigated, reactive iron coatings are characterized with a suite of analyses under anaerobic conditions. To distinguish surface coating mineralogy, X-ray diffraction, X-ray fluorescence, and field-emission scanning electron microscopy with an energy dispersive X-ray analyzer were applied along with a six-step sequential extraction process. The cycling of Fe and S, as an important contribution and indicator of ongoing natural attenuation processes for constituents of concern (COC), was delineated by using data from multiple and complementary analyses for isolating and identifying iron phases. Along with groundwater chemistry, contaminant concentrations, and microbial genera, attenuation of COCs is expected to be active and sustainable in redox transition zones, where there is an abundance of reactive iron mineral coatings cycling through biogeochemical reactions. Reactions in other redox transition zones may be limited where iron mineral coatings are not dominant.

Impacts of cryogenic sampling processes on iron mineral coatings in contaminated sediment.

This study focused on comparing iron mineral coatings found in contaminated sediments from a cryogenic (Cryo Core) core versus an Anaerobic Core (collected under oxygen-free and ambient conditions). After thawing the Cryo Core in an oxygen-free glovebox, a suite of analyses was applied on sediments from both cores: pH, redox potential, X-ray fluorescence (XRF), X-ray diffraction (XRD), and field-emission scanning electron microscopy (FESEM) with energy dispersive X-ray analyzer (EDX). Among the iron minerals identified, crystalline pyrite was found throughout the Cyro Core sediment samples, which is in contrast to that observed for the Anaerobic Core. Moreover, mackinawite and greigite that were ubiquitous in the Anaerobic Core were not observed in Cryo Core samples. To better understand why the metastable minerals were not present, a freeze/thaw process was simulated on Anaerobic Core samples using a liquid­nitrogen quench with surface coatings characterized by FESEM/EDX. In these quenched samples, mackinawite was no longer observed, and in its place was pyrite. In addition, both greigite and pyrite were found to be unique morphologically after quenching. Dissolution and re-precipitation of iron sulfide coatings during the freeze/thaw process appears to affect the geochemistry of the pore water through two main mechanisms of freeze-concentration and freezing potential.

Combined use of chemotherapeutics and oncolytic adenovirus in treatment of AFP-expressing hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) which is always refractory to most chemotherapeutic agents may result in poor survival of patients with advanced HCC. Oncolytic adenovirus is a new form for cancer gene therapy via its ability to replicate and kill tumor cells in a tumor-specific manner. In order to eradicate tumors effectively, the combination of chemotherapeutic agents and oncolytic adenovirus has been considered. This study aimed to systematically analyze the possibility of synergistic cytotoxicity of oncolytic adenoviruses in combination with chemotherapeutic agents. METHODS: Several types of human HCC cell lines were used to determine the specificity and cytotoxicity of oncolytic adenovirus Ad5-HC and Ad5-AFP (IRES) by measuring cell viability in vitro and antitumor efficiency in vivo. The cytotoxicity of Ad5-HC and Ad5-AFP (IRES) combined with chemotherapeutic agents were also assessed by the methyl thiazolyl tetrazolium assay. RESULTS: Both Ad5-HC and Ad5-AFP (IRES) were significantly cytotoxic to HCC cells with great specificity in vitro and in vivo. The combination of oncolytic adenovirus with 5-FU, doxorubicin, and paclitaxel was synergistically effective for the killing of HCC cells. CONCLUSIONS: These data suggest that oncolytic adenovirus sensitize tumors to chemotherapy and the combination therapy of chemotherapeutic agents and oncolytic adenovirus has an enhanced antitumor effect on HCC cells.

Graphene quantum dots with nitrogen-doped content dependence for highly efficient dual-modality photodynamic antimicrobial therapy and bioimaging.

Reactive oxygen species is the main contributor to photodynamic therapy. The results of this study show that a nitrogen-doped graphene quantum dot, serving as a photosensitizer, was capable of generating a higher amount of reactive oxygen species than a nitrogen-free graphene quantum dot in photodynamic therapy when photoexcited for only 3 min of 670 nm laser exposure (0.1 W cm-2), indicating highly improved antimicrobial effects. In addition, we found that higher nitrogen-bonding compositions of graphene quantum dots more efficiently performed photodynamic therapy actions than did the lower compositions that underwent identical treatments. Furthermore, the intrinsically emitted luminescence from nitrogen-doped graphene quantum dots and high photostability simultaneously enabled it to act as a promising contrast probe for tracking and localizing bacteria in biomedical imaging. Thus, the dual modality of nitrogen-doped graphene quantum dots presents possibilities for future clinical applications, and in particular multidrug resistant bacteria.

A Modified Spontaneously Closed Defunctioning Tube Ileostomy After Anterior Resection of the Rectum for Rectal Cancer with a Low Colorectal Anastomosis.

The aim of this study is to introduce a new technique of modified spontaneously closed defunctioning tube ileostomy after anterior resection of the rectum for rectal cancer with a low colorectal anastomosis. Patients with rectal cancer who underwent anterior resection of rectum with a low colorectal anastomosis and chose a modified defunctioning tube ileostomy between March 2012 and August 2013 were retrospectively reviewed. Data on the success of the operation procedures, post-operative hospital stay, and post-operative tube ileostomy-related complications were analyzed. One hundred fifty-two patients (87 males and 65 females; 57.1 ± 17.4 years) undergoing the modified defunctioning tube ileostomy after anterior resection for rectal cancer were included. The post-operative hospital stay was 11.9 ± 3.2 days. The tube was removed on days 22.6 ± 4.1 after operation and the ileostomy wound closed spontaneously within 13.1 ± 1.9 days. Twenty-five patients felt tube-associated pain or discomfort, which was relieved after a period of adaptation and appropriate tube adjustment. Nine patients suffered from tube blockage and were treated successfully with saline irrigation. Two patients had intestinal obstruction, which was resolved with conservative treatment. Three patients developed leakage of the distal anastomosis: two were successfully treated with conservative measures and the other completely recovered after reoperation. The modified spontaneously closed defunctioning tube ileostomy appears efficacious and safe. This technique may be used to protect the distal anastomosis and simultaneously decrease the ileostomy complications, and minimize the morbidity and mortality associated with stoma takedown.

An improved process for high nutrition of germinated brown rice production: Low-pressure plasma.

Brown rice was exposed to low-pressure plasma ranging from 1 to 3kV for 10min. Treatment of brown rice in low-pressure plasma increases the germination percentage, seedling length, and water uptake in laboratory germination tests. Of the various treatments, 3-kV plasma exposure for 10min yielded the best results. In germinating brown rice, α-amylase activity was significantly higher in treated groups than in controls. The higher enzyme activity in plasma-treated brown rice likely triggers the rapid germination and earlier vigor of the seedlings. Low-pressure plasma also increased gamma-aminobutyric acid (GABA) levels from ∼19 to ∼28mg/100g. In addition, a marked increase in the antioxidant activity of brown rice was observed with plasma treatments compared to controls. The main finding of this study indicates that low-pressure plasma is effective at enhancing the growth and GABA accumulation of germinated brown rice, which can supply high nutrition to consumer.

Two-Photon Photoexcited Photodynamic Therapy and Contrast Agent with Antimicrobial Graphene Quantum Dots.

A graphene quantum dot (GQD) used as the photosensitizer with high two-photon absorption in the near-infrared region, a large absolute cross section of two-photon excitation (TPE), strong two-photon luminescence, and impressive two-photon stability could be used for dual modality two-photon photodynamic therapy (PDT) and two-photon bioimaging with an ultrashot pulse laser (or defined as TPE). In this study, a GQD efficiently generated reactive oxygen species coupled with TPE, which highly increased the effective PDT ability of both Gram-positive and -negative bacteria, with ultralow energy and an extremely short photoexcitation time generated by TPE. Because of its two-photon properties, a GQD could serve as a promising two-photon contrast agent for observing specimens in depth in three-dimensional biological environments while simultaneously proceeding with PDT action to eliminate bacteria, particularly in multidrug-resistant (MDR) strains. This procedure would provide an efficient alternative approach to easily cope with MDR bacteria.

Graphene quantum dots conjugated with polymers for two-photon properties under two-photon excitation.

Few studies have investigated the two-photon properties of graphene quantum dots (GQDs) and GQD-conjugated polymers. The results of the present study revealed that conjugated polymers containing nitrogen and sulfur atoms caused higher quantum confinement of emissive energy to be trapped on the surface of nanomaterials, resulting in a high-photoluminescence quantum yield and notable two-photon properties. Additionally, the nanomaterials generated no reactive oxygen species-dependent oxidative stress on cells and served as promising two-photon contrast probes.

Comparison of hand-assisted laparoscopy with open total colectomy for slow transit constipation: a retrospective study.

OBJECTIVE: To compare the efficacy and safety of hand-assisted laparoscopic colectomy (HALC) and open colectomy (OC) for patients with slow transit constipation (STC). METHODS: Data of patients with STC who underwent total colectomy from January 2008 to December 2012 were retrospectively reviewed after clinical evaluation and an exclusion of secondary causes. These patients were further divided into the HALC and OC groups. Patients' outcomes, including intraoperative and postoperative data on their recovery and complications were compared between the two groups. RESULTS: A total of 68 patients with STC were finally enrolled in the study, including 32 in the HALC group and 36 in the OC group. The baseline characteristics did not significantly differ between the two groups. Compared with the OC group, patients in the HALC group had a shorter length of incision, a longer operative time and less blood loss volume. There was no conversion to OC for patients undergoing HALC and no intraoperative complications in both groups. Furthermore, after operation, patients in HALC group experienced less pain (3.4 ± 0.7 vs 4.8 ± 1.0), earlier first passage of flatus (58.3 ± 6.3 h vs 73.4 ± 13.0 h), shorter length of postoperative hospital stay (8.8 ± 1.2 days vs 11.3 ± 1.7 days) but higher medical cost (RMB 33 979 ± 3 135 vs RMB 29 828 ± 3 216). The overall postoperative complications and the satisfaction in defecation were comparable in the two groups. CONCLUSION: HALC is a safe, minimally invasive and effective surgical alternative for treating STC, which is comparable to OC.

[Immunostimulator CH2a bearing thiazolidin-4-one promotes the function of human iNKT cells in vitro].

OBJECTIVE: To explore the immunostimulatory effect of immunostimulant CH2a bearing thiazolidin-4-one on human invariant natural killer T (iNKT) cell function in vitro. METHODS: Peripheral blood mononuclear cells (PBMCs) were obtained from healthy adults, and then amplified with α-Galcer and IL-2 in vitro. The iNKT cells were isolated from these proliferating cells by magnetic-activated cell sorting (MACS) method. The purified iNKT cells were labled with 5-(and 6)-carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and then incubated with CH2a for functional analysis, including cell proliferation, expressions of IFN-γ and IL-4 by flow cytometry, proliferation rate and cytotoxicity by MTT assay. In additon, ELISA was performed to determine the levels of IFN-γ and IL-4 in cell culture media. RESULTS: CH2a significantly promoted the proliferation of iNKT cells induced by IL-2 in vitro, stimulated the release of both IFN-r and IL-4, and led to the increase in IFN-γ/IL-4 ratio. More importantly, the cytotoxicity of iNKT was also markedly elevated under the stimulation of CH2a. CONCLUSION: Immunostimulant CH2a probably promote the production of Th1-like cytokines and the differentiation of Th0 to Th1, so as to improve cellular immune function. In addition, CH2a could significantly enhance the cytotoxicity of iNKT cells.

Immunomodulatory effects of feruloylated oligosaccharides from rice bran.

Feruloylated oligosaccharides (FOs), the ferulic acid ester of oligosaccharides, can be released either by the enzymatic or mild acid hydrolysis of arabinoxylans present in cereal bran, and are usually considered as natural antioxidants. However, no related research is available to explain their immunomodulatory effects. This report elucidated their immunomodulatory effects through the variations of pro-inflammatory mediators in vitro. FOs were obtained from the mild acid hydrolysis of rice bran. We found that FOs (0.1-100 µg/ml) induced tumour necrosis factor alpha (TNF-α), IL-1ß, IL-6, nitric oxide (NO) and PGE(2) production in unstimulated macrophages, RAW264.7 cells. Furthermore, pre- and post-treated FOs (0.1-100 µg/ml) dose-dependently suppressed TNF-α, IL-1ß, IL-6 and NO production, and induced IL-10 production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells without exerting cytotoxicity. As a result anti-inflammatory and therapeutic activities were revealed. It is noteworthy that prostaglandin E(2) (PGE(2)) production was significantly suppressed at an FO level of 100 µg/ml. The in vitro assessment of inflammatory mediators should be useful in further characterising the effects of FOs on immunomodulation. Moreover, it will create the economical value of rice bran, which has long been considered as conventional agricultural wastes.