Some mechanisms involved in the development of iron toxicity symptoms in the rice plant

Bronzing of the rice plant in Ceylon has been postulated as iron toxicity (1, 2). The symptoms are characterized by the development of scattered reddish brown spots on the lower leaves; the spots spread over the leaves, the whole leaf becomes brown, and the lower leaves start to turn dark gray and die. “Akagare” in Japan is also considered to be related to excess of iron (3, 4).     

Contrast-enhanced CT features of pyloric lesions in 17 dogs: Case series

Pyloric outflow obstructions can be caused by several types of lesions. When a thickened gastric wall and pyloric mass are detected, malignant neoplasia must be differentiated from chronic hypertrophic pyloric gastropathy. CT can characterize gastric tumors. However, based on the authors’ review of the literature, there is limited information about the CT findings of pyloric lesions. The purpose of this retrospective case series study was to assess the CT findings of canine pyloric lesions. The following CT parameters were recorded: anatomical area, involved area, lesion shape, growth patterns of wall thickening lesions, enhancement pattern of the lesion in the early and delayed phases, lymphomegaly, and pulmonary metastasis. Seventeen dogs were included in this study and had the following final diagnoses: hyperplasia (five dogs), adenoma (five dogs), adenocarcinoma (three dogs), gastrointestinal stromal tumor (GIST; two dogs), polyposis (one dog), and pyogenic granuloma (one dog). Hyperplasia, adenoma, and polyposis formed mass lesions that involved the mucosal layer. Lymphomegaly was detected in two Jack Russell terriers with hyperplasia; however, the causes were unknown because we did not perform biopsies. All adenocarcinomas formed wall-thickened lesion that involved the outer layer, with lymphomegaly. All GISTs formed mass lesion that involved the outer layer. The pyogenic granulomas formed symmetric wall-thickened lesion that involved the mucosal and outer layers. CT facilitated the characterization of canine pyloric lesions using contrast enhancement, based on the involved area and lesion shape. However, polyposis may require caution in diagnosis based on CT findings alone.     

Echocardiographic Evaluation of Myocardial Changes Observed After Closure of Patent Ductus Arteriosus in Dogs

Background

Closure of PDA can be associated with echocardiographic changes including deterioration of LV systolic function. Although PDA is commonly encountered in dogs, few comprehensive reports of echocardiographic changes in dogs with PDA closure are available.

Objectives

To evaluate the short‐term echocardiographic changes observed after PDA closure in dogs using strain analysis.

Animals

Seventeen client‐owned dogs with left‐to‐right PDA.

Methods

Echocardiographic evaluations, including standard echocardiography and two‐dimensional tissue tracking (2DTT), were performed before and within 3 days of PDA closure.

Results

Preclosure examination showed LV and left atrial dilatation indicating volume overload as a result of PDA. Closure of PDA resulted in significant reduction of LVIDd (<.0001) and LA/Ao (0.01) without change in LVIDs, suggestive of decreased preload. Postclosure LV systolic dysfunction was observed with significant decreased in FS (<.0001) and strain values (P = .0039 for radial strains, P = .0005 for circumferential strains). Additionally, significant LV dyssynchrony (P = .0162) was observed after closure of PDA.

Conclusions and Clinical Importance

Closure of PDA resulted in decreased preload as a result of alleviation of LV volume overload, which in turn caused transient deterioration of LV systolic function. Additionally, this study demonstrated that strain analysis is load dependent. Therefore, care should be taken when interpreting strain measurements as an indicator of LV systolic function.     

Factors influencing steel tool wear when milling wood

The wear of high speed steel cutting tools after milling wood of four selected wood species was studied. For the experiments wood specimens were chosen with very different silica contamination, wood density, and high temperature corrosivity (HTC) of wood towards tool material. Analyses performed show that the silica content and wood density display poor linear correlation with the cutting tools wear, while the correlation of the HTC appeared very good. The silica contamination and the HTC effects overshadow each other. Thus, a theoretical multivariable simulation of the cutting edge wearing process, employing all experimental variables, was applied, providing a very good explanation of the analyzed problem.     

Performance of coated carbide tools in turning wood-based materials: Effect of cutting speeds and coating materials on the wear characteristics of coated carbide tools in turning wood-chip cement board

This paper reports on the performance of coated carbide tools in turning wood-chip cement board. The coating materials studied were titanium carbonitride (TiCN), titanium nitride (TiN), chromium nitride (CrN), and titanium nitride/aluminum nitride (TiN/AlN), which were synthesized on the P30 carbide substrate. The aim is to investigate the effect of coating materials and cutting speeds on the wear characteristics of the coated carbide tools. Cutting tests were performed when turning wood-chip cement board at cutting speeds of 30, 40, 50 and 60 m/s, a depth of cut of 1mm, and a feed of 0.05 mm/rev. The results of the study show that the coated carbide tools provided better performance than the P30 carbide tool, especially in terms of reducing the progression of the wear rate and clearance wear. The TiN/AlN-coated carbide tool showed the smallest increase in both wear rate and clearance wear with an increase in cutting speed and had the longest tool life among the coated carbide tools investigated. Though the TiCN-coated carbide tool was observed to have a low wear rate and low clearance wear for cutting speeds of 30 and 40m/s, when the cutting speeds were >50m/s its wear rate and clearance wear were almost the same as those of CrN-and TiN-coated carbide tools, which had high values for these parameters.Part of this paper was presented at the 21st IUFRO World Congress, August 2000, Kuala Lumpur, Malaysia     

The critical rotational speed of circular saw: simple measurement method and its practical implementations

Operation safety during sawing operations as well as dimensional accuracy and surface roughness depend on circular saw dynamic features among other factors such as circular saw blade accuracy and static/dynamic properties of the machine tool. Manufacturers of saw blades have an obligation to mark tools with a value stating the maximum allowed rotational speed for each saw. However, in some cases the value indicated on the saw corresponds to the critical rotational speed or is dangerously close to this critical value. Saw operation at the critical rotational speed is inadvisable and may result in serious injury or depreciation of product quality. This report outlines a simple methodology for evaluation of circular saw critical rotational speed. The assessment was conducted with a camera vision technique on the basis of an impulse test. Results are compared with theoretically calculated critical rotational speeds and the marks on saw blades.     

Tetrahydrofolate-dependent vanillate and syringateO-demethylation links tightly to one-carbon metabolic pathway associated with amino acid synthesis and DNA methylation in the lignin metabolism ofSphingomonas paucimobilis SYK-6

Sphingomonas paucimobilis SYK-6 strain can degrade various lignin-related compounds. In the lignin metabolic pathway of this bacterium, vanillate and syringate are demethylated by the tetrahydrofolate (THF)-dependentO-demethylation system, which requires the enzymatic function of LigH. Upstream of theligH gene is the 5,10-methylene-THF reductase gene. Its gene product was essential for one-carbon metabolism involved in the amino acid synthesis and DNA methylation in all organisms. When themetF gene was inactivated in the genome of SYK-6, the resultant mutant, DLmetF, could not grow on vanillate and syringate as a sole carbon source. Furthermore, DLmetF showed significant accumulation of methyl-THF as a result of vanillate and syringateO-demethylation. We report here that THF-dependent vanillate and syringateO-demethylation links tightly to the one-carbon metabolic pathway that is associated with amino acid synthesis and DNA methylation, and the methyl group is the sole one-carbon source inS. paucimobilis SYK-6.     

Evaluation of surface smoothness using a light-sectioning shadow scanner

A new type of sensor for rapid three-dimensional evaluation of surface geometrical properties is presented. Light emitted with a fixed small angle to the surface plane by a projector is directed into the measured surface. A curtain installed in the light path close to the surface creates a shadow on the measured surface. The shape of the border between bright (highly lit area) and dark (shadow area) is a profile section of the surface. The camera installed over the measured surface captures an image of the border and a digital signal processor using image analysis techniques digitizes the profile section. The shadow scanner method evaluated here could be used for rapid and accurate scans of surfaces of various porous materials, particularly wood, veneer, paper, fiberboards, leaves, and similar materials in both laboratory and industrial applications. The simplicity of the sensor is an advantage because it makes the system easy to maintain, resistant to breakage, and inexpensive. Its straightforward nature and high accuracy enables the method to be utilized for on-line measurement, and therefore it is suitable for industrial application.     

Effect of combinations of wood and counterface materials on three-body abrasive wear

The abrasion characteristics of various combinations of wood and counterface materials in three-body abrasive wear were investigated. Various wood samples were examined in combination with wood, plastic, and metal counterface materials. The wear coefficient in the wood samples was calculated as the wear volume of the friction surface divided by the sliding distance and the applied load. The results showed that the wear coefficient was smaller in cases where the wood samples had greater yield stress. The wear coefficient increased as the yield stress of the various counterface materials increased, reaching a maximum value and then decreased as the yield stress increased. This result indicated that a peak value existed for the wear coefficient in combination with the counterface material.Part of this report was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001