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The Exodus Project Group

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Elijah Rogers
Elijah Rogers

Thrash Metal Method Pdf 17

Aquaculture is one of the fastest growing agro-industries as it presently accounts for nearly 50% of all fish for direct human consumption and 43% of total seafood supply. Fish provide about 20% average daily intake of animal protein for about 3.2 billion people globally. The treatment of aquaculture in recent years for the mitigation of heavy metals and other contaminants has been gaining traction due to the benefits of aquaculture to both man and the environment. This paper provides a review of the sources, impacts, and the various methods that have been deployed in recent years by various researchers for the treatment of heavy metal contaminated aquaculture. Related works of literature were obtained and compiled from academic search databases and were carefully analysed in this study. The dangers these metals pose to the sustainability of aquaculture were studied in this review. Studies indicate that some heavy metals, such as mercury, lead, and cadmium, due to their long-term persistence in the environment, allow them to accumulate in the food chain. Mitigation techniques such as adsorption, bio-sorption, and phytoremediation have been deployed for the treatment of heavy metal contaminated aquaculture. Some research gaps were also highlighted which could form the basis for future research, such as research centred on the effects of these metals on the embryonic development of aquaculture organisms and the alterations the metals caused in their stages of development.

thrash metal method pdf 17

Industrial application of carbon nanotubes (CNTs) as high-performance composites, conductive additives in secondary batteries and corrosion-preventing coatings is increasing.1 The possibility that CNTs cause serious lesions such as mesotheliomas because they are nano fibrous materials similar in shape to asbestos is a concern. Takagi et al.2 and Poland et al.3 reported that peritoneal administration of multi-walled CNTs induce inflammation and mesothelioma-like lesions in abdomen mesothelium. Prior to those reports, CNTs were used in rigorous biological evaluations.4, 5 Mercer et al.6 showed that multi-walled CNT distribution to the lymph nodes, diaphragm, chest wall and extrapulmonary organs in mice after inhalation exposure, indicating the need to investigate CNTs biokinetics. In addition to occupational exposures, exposure through biomaterial, medical diagnosis and treatment applications is a concern.7 Particularly in drug-delivery systems and imaging applications, CNTs are directly injected in veins and their whereabouts in vivo must be essentially understood. Unavoidably, CNTs used as scaffolds for tissue regeneration are transferred to the other organs through the blood and lymphatic circulation. Thus, methods of CNT biokinetics evaluation are needed urgently.

CNT biokinetics has been investigated after intravenous administration.8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 One method of in vivo CNT distribution monitoring is to assay tissue preparations of all organs after CNTs are administered. However, preparations vary and measurement is not quantitative.9 Although single-walled CNTs can be assayed in vivo by Raman spectroscopy owing to its intrinsic signatures, multi-walled CNTs including double-walled CNTs (DWCNTs) cannot be assayed using this method.10 Many current methods propose labeling CNTs with carbon isotopes of 13C or 14C,8, 12, 18 and functionalizing the surface with carboxyl groups or coat the surface with colloidal metal particles.14, 15, 16, 17 Labeling requires a special facility to handle and synthesize isotope-labeled CNTs. Preparing labeled CNTs is not difficult but the physical, chemical or biological characteristics of the original CNTs may be modified in the process.19, 20 Furthermore, exfoliation of functionalized moieties or surface substances will occur during measurement.21 Therefore, an alternative method that does not require tissue preparation would be desirable.

The present work aims at development of an advanced in situ imaging method of CNT kinetics evaluation in vivo. DWCNTs filled with heavy metal particles were prepared to achieve our goal. Doped CNTs (called peapods) are designated doped particles @CNT types. As such, peapod technology is expected in the future to find a broad range of in vivo applications as nanocontainers.22 The first peapod, C60@ single-walled CNT, was synthesized using fullerene C60.23, 24 However, C60 modifications significantly alter CNT characteristics. In the present work, marker molecules were directly inserted into the cylindrical hollow structure unique to CNTs.25, 26, 27 The peapods were used to evaluate biokinetics in tissues and in vivo. We found that the distribution of CNTs in the body can be determined without tissue preparation.

To establish an in situ method of biokinetics evaluation, detection limits were demonstrated on MRI analysis. The results indicate that our approach is promising. Tail vein administration of Gd-peapods resulted in significant differences in CNR between peapods in lungs and peapods in saline solution or between peapods in saline and pristine CNTs in saline solution; there was no difference in CNR between pristine CNTs and saline, though the lung color was very different from that of the control. It suggests that the accumulation and persistence of peapods in the lungs intensified MRI signals significantly. Histopathologically, Gd-peapod aggregates were found in the pulmonary artery and capillaries in all parts of the lungs, which corresponded to the increase found in MRI signal intensity, but no aggregates were found in the livers, spleens and kidneys and no increase in MRI signal intensity was found in those organs. The change in signal intensity was dose-dependent in all samples so that this protocol is applicable to quantitative determination of peapod biokinetics.

As far as we know, no studies have evaluated the biokinetics of gadolinium-encapsulated peapods as in the present study, although one study evaluated the biokinetics of CNTs with gadolinium-modified surfaces.32 Judging from the mass ratio of Gd to Cl atoms by XRF analysis, the substance within DWCNTs was identified as GdCl3 (Figure 1b). Elemental mapping analysis by energy dispersive X-ray spectroscopy revealed both Gd and Cl in CNT bundles, with GdCl3 encapsulated in the CNTs and not found outside (data not shown). With regard to the amount of gadolinium encapsulated, no quantitative method is currently available for measuring concentrations within the peapod interior except XRF. Essentially XRF analysis is a nondestructive technique, so it allows direct measurement of the amount of gadolinium encapsulated in peapods used for animal experimentation, but in case of inductive coupled plasma atomic emission spectrometry or another destructive analytical method Gd-peapods sample will be completely destroyed. With this in mind, in the present study, we obtained adequate accuracy through relative evaluation of peapod concentration by determining the percentage mass ratio of Gd in peapods using XRF measurements, and comparing the results with known Gd concentrations measured on MRI images. To confirm Gd-peapod stability in saline, the amount of Gd in saline after leaving Gd-peapods in saline for 6 months was evaluated by MRI. The signal intensity of Gd-peapods remained high, with no significant desorption of Gd particles observed (Supplementary Figure S2). In addition, TEM examination revealed the absence of Gd leakage even after electron-beam irradiation. For these reasons, it can be concluded that Gd-peapods are also stable in vivo and do not release Gd.

The proposed method is useful for in vivo investigation because it does not require sample slicing or incineration of tissues to weigh the carbon amount in tissues. This technique might be useful particularly in the application of drug-delivery systems and in imaging with the aim of seeing how CNTs circulate and accumulate in tissues and organs. In conclusion, the first in situ method suitable for CNTs biokinetics evaluation was developed and demonstrated.


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