Evaluation of Acute Toxicity and Antioxidant Response of Earthworm Exposed to a Lignin-Modified Crosslinked Hydrogel

Hydrogels are polymers of great importance due to their multiple applications, which have led to an exponential increase in their production. However, once they have fulfilled their function, they become waste and their ecotoxicological effects are unknown. The aim of the present study was to evaluate the acute toxicity and total antioxidant capacity of the earthworm (Eisenia fetida) exposed to a terpolymeric hydrogel (acrylic acid, acrylamide, and 2-acrylamido-2-methyl-1-propane-sulfonic acid) crosslinked with modified kraft lignin. Four different amounts of hydrogel per unit area were evaluated (0.0924, 0.1848, 0.9242, and 1.848 mg hydrogel/cm²) plus a control, and three replicates were performed for each group. Starting from the amount of 0.1848 mg hydrogel/cm², the earthworms showed physiological and behavioral alterations; at higher amounts, 0.9242 and 1.848 mg hydrogel/cm², more acute signs were observed with mortality rates of 51.7% and 100%, respectively. On the other hand, the antioxidant activity assay showed that the higher the hydrogel exposure amount, the higher the oxidative stress, as evidenced by lower antioxidant activity (67.09% inhibition of the ABTS^●+ radical). Therefore, we concluded that the lignin-modified hydrogel generated oxidative stress and acute lethal toxic effects in Eisenia fetida.

Personality Structure of Mexican Americans Using the Comrey Personality Scales

The Comrey Personality Scales (CPS) were used to examine the personality structure of 176 Mexican American college students. A majority of the eight factors maintained substantial loadings and corresponded closely with Comrey's normative sample as well as with Brazilian and New Zealand samples. Two factors, Conformity and Orderliness, showed the weakest fit across all four groups. Overall, the CPS shows adequate measurement properties for "normal" personality assessment among Mexican Americans and is preferable to instruments such as the Minnesota Multiphasic Personality Inventory (MMPI). However, the external validity of the CPS with clinical populations must first be determined prior to its use to assess psychopathology among Mexican Americans.

Spectroscopic characterization of N-doped single-walled carbon nanotube strands: an X-ray photoelectron spectroscopy and Raman study

We have studied in detail the carbon and nitrogen bonding environments in nitrogen-doped single-walled carbon nanotubes (SWCNTs). The samples consisting of long strands of N-doped SWCNTs were synthesized using an aerosol assisted chemical vapor deposition method involving benzylamine-ethanol-ferrocene solutions. The studied samples were produced using different benzylamine concentrations in the solutions, and exhibited a maximum concentration of ca. 0.3%at of N, determined by X-ray photoelectron spectroscopy (XPS). In general, we observed that the ratio between substitutional nitrogen and the pyridine-like bonded nitrogen varied upon the precursor composition. Moreover, we have observed that the sp2-like substitutional configuration of the C-N bond does not exceed the 50% of the total N atomic incorporation. In addition, we have characterized all these samples using Raman spectroscopy and electron microscopy.

Production and characterization of single-crystal FeCo nanowires inside carbon nanotubes

We describe the synthesis of novel monocrystalline FeCo nanowires encapsulated inside multiwalled carbon nanotubes (MWNTs). These FeCo nanowires exhibit homogeneous Fe and Co concentrations and do not contain an external oxide layer due to the presence of insulating nanotube layers. The method involves the aerosol thermolysis of toluene-ferrocene-cobaltocene solutions in inert atmospheres. The materials have been carefully characterized using state-of-the-art high-resolution transmission electron microscopy (HRTEM), electron-energy-loss spectroscopy (EELS), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), electron diffraction, HREELS-STM elemental mapping, X-ray powder diffraction, and SQUID magnetometry. We noted that the formation of FeCo alloys occurs at relatively low pyrolytic temperatures (e.g., 650-750 degrees C). These single-crystal nanowires, which have not been reported hitherto, always exhibit the FeCo (110) plane parallel to the carbon nanotube axis. The FeCo nanomaterials have shown large coercive fields at room temperature (e.g., 900 Oe). We envisage that these aligned ferromagnetic nanowires could be used in the fabrication of high-density magnetic storage devices and magnetic composites.

Post-match disorder: how to cope when your program fails to match

BACKGROUND

Faculty, residents, and staff of programs that fail to match in the National Resident Matching Program may develop a Post-Match Disorder (PMD) that can threaten a program's self-esteem, teamwork, and ability to function. The symptoms of PMD include manifestations of shock, anger, and depression. This report describes the experience of one program that unexpectedly failed to match and the subsequent development of PMD among program personnel.

METHODS

A survey of applicants who did not match with the program was conducted.

RESULTS

The results indicated that the applicants perceived the program as having many positive attributes and had ranked it highly--but not high enough to match.

CONCLUSIONS

The awareness that applicants perceived the program positively helped alleviate symptoms of PMD and allowed faculty and residents to focus on subsequent resident recruitment, leading to a successful match in the following year.

mRNA from frog corneal epithelium increases water permeability in Xenopus oocytes

PURPOSE

To investigate the existence of a water channel in the frog corneal epithelium by studying the osmotic water permeability (Pf) of Xenopus oocytes expressing the mRNA message from frog corneal epithelium.

METHODS

Total RNA was obtained from corneal epithelium by a single-step phase separation method, and poly A+ RNA was isolated using oligo-dT columns. This mRNA was injected into the oocytes. After a 48-hour incubation, oocyte volume changes elicited by a hypoosmotic solution were measured with a computerized video system.

RESULTS

Oocytes injected with 50 nl mRNA (1 microgram/microliter) showed a significant increase in Pf compared to water-injected controls (8.4 +/- 1.5 to 17.5 +/- 1.9 cm.sec-1 x 10(-4), P < 0.005). mRNA-injected oocytes exposed to a higher external [Cl-] showed a heightened permeability. Furthermore, Pf of oocytes exposed to a solution containing the recognized water-channel blocker HgCl2 was significantly lower than the Pf of mRNA-injected oocytes not exposed to HgCl2.

CONCLUSIONS

Evidence was found for a water channel in the frog corneal epithelium because oocytes injected with the epithelial mRNA manifested increased water permeability. The increase in water permeability was larger in the presence of external Cl- and was inhibited by HgCl2. This finding correlates with measurements of Pf in the intact epithelium in which apical Cl- induced an increase in transepithelial water permeability prevented by HgCl2.