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PubMed2005

Demixing behavior in two-dimensional mixtures of anisotropic hard bodies.

Scaled particle theory for a binary mixture of hard discorectangles and for a binary mixture of hard rectangles is used to predict possible liquid-crystal demixing scenarios in two dimensions. Through a bifurcation analysis from the isotropic phase, it is shown that isotropic-nematic demixing is possible in two-dimensional liquid-crystal mixtures composed of hard convex bodies. This bifurcation analysis is tested against exact calculations of the phase diagrams in the framework of the restricted-orientation two-dimensional model (Zwanzig model). Phase diagrams of a binary mixture of hard discorectangles are calculated through the parametrization of the orientational distribution functions. The results show not only isotropic-nematic, but also nematic-nematic demixing ending in a critical point, as well as an isotropic-nematic-nematic triple point for a mixture of hard disks and hard discorectangles.

Journal Article↗
PubMed1991

Transient expression of mouse hair keratins in transfected HeLa cells: interactions between "hard" and "soft" keratins.

Although it has been shown previously that an acidic (type I) "soft" keratin can interact with many basic (type II) "soft" keratins to form 10-nm intermediate filaments, it has been unclear whether "soft" keratins are compatible with the "hard" keratins typically found in hair and nail. To address this issue and to generate more structural information about hard keratins, we have isolated and sequenced a cDNA clone that encodes a mouse hair basic keratin (b4). Our sequence data revealed new information regarding the structural conservation of hard keratins as a group, being significantly different from soft keratins. Using expression vectors containing appropriate cDNA inserts, we studied the expression of this basic (b4) as well as an acidic (a1) mouse hair keratin in HeLa cells. The expression of these alien hair keratins in the transfected cells was surveyed using a panel of monoclonal and polyclonal antibodies. Our results indicated that the basic and acidic hair keratin readily incorporated into the existing endogenous soft keratin network of HeLa cells. Overproduction of hair keratin, however, occasionally led to the formation of cytoplasmic aggregates containing both hard and soft keratins. These data suggest that although small amounts of newly synthesized hair keratins can incorporate into the "scaffolding" of the preformed soft keratin filament network, possibly through dynamic subunit exchange, overproduction of hard keratins can lead to the partial collapse of the soft keratin network. These observations, along with the deduced amino acid sequence data, support and extend the concept that hard and soft keratins, although closely related, are divergent enough to justify their being divided into two separate subgroups.

Animals↗
PubMed1991

Water hardness does not contribute substantially to the high coronary mortality in cold regions of Sweden.

Earlier studies have shown an association between cold climate and high coronary mortality. The aim of this study was to elucidate in more detail the effect of drinking water hardness on this association. Drinking water parameters were obtained from 259 municipalities in Sweden over a 10-year period. During the same period a 'cold index' was calculated for each municipality. Standardized coronary mortality rates in men aged 40-64 years were used. A negative association was found between water hardness and coronary mortality (coefficient of determination k = 0.080). A much stronger association was found between coronary mortality and cold index (D = 0.389). When coronary mortality was explained by both water hardness and cold index, the association was not significantly strengthened (D = 0.391). Water hardness was negatively correlated with cold index (r = 0.55). We conclude that the association between cold climate and coronary mortality was stronger than that between drinking water hardness and coronary mortality, and that it persisted after stratification for water hardness.

Adult↗
PubMed1982

A clinical study of the number of occlusal tooth contacts in the intercuspal position at light and hard pressure in adults.

Young adults and Adults were investigated with respect to the number of occlusal tooth contacts. In the habitual intercuspal position (centric occlusion) there was, on a highly significant level, a smaller number of tooth contacts at light pressure than at hard pressure. When Young adults were compared with Adults there was a significantly smaller number of contacts at light pressure in the Adults. During hard pressure, there was no significant difference between the groups. There was no significant difference in the number of tooth contacts at light and hard pressure between patients referred for orthodontic treatment and others. In the group of Young adults, approximately 5% of the contacts appeared on a restoration at light pressure, while approximately 10% did so at hard pressure. There was no significant difference between those with and without contacts on a restoration with respect to the number of contacts at light and hard pressure. If the number of contacts on study casts of 106 adults (Adults-A), after occlusal adjustment in an articulator, was compared with the number of hard pressure contacts found clinically in thirty-five of them, no significant difference was found.

Adult↗
PubMed1987

Inorganic particulates in pneumoconiotic lungs of hard metal grinders.

Data from the analysis of lung dust in 16 metal grinders who had been exposed to hard metals between five and 44 years is reported. The mean latent time between the first exposure and analysis in biopsy or necropsy specimens was 33.6 years. Mineralogical and elementary analysis by a variety of techniques showed small or trace amounts of hard metal in all lungs. Many specimens, however, did not contain all hard metal components, cobalt, for example, being detected in four cases only. All the lungs contained quartz and silicates and in most of the necropsy cases carborundum and corundum could also be shown. Histologically no specific pattern was found. The appearances included mixed dust nodular pneumoconiosis, diffuse interstitial lung fibrosis, and foreign body and sarcoid like granulomatous changes. In view of the mixed dust exposure of the hard metal grinders and the variable histological appearance we think that the term "mixed dust pneumoconiosis in hard metal grinders" is more appropriate than "hard metal lung" to describe this condition.

Adult↗
PubMed1996

Epidemiological study of hard metal asthma.

OBJECTIVES: To elucidate factors contributing to hard metal asthma, the entire workforce of a corporation producing hard metal tools (n = 703) was examined. METHODS: The variables evaluated were the atopy reflected by immunoglobulin E (IgE) antibody against mite allergen, history of exposure to hard metal, smoking, concentration of airborne cobalt, specific IgE antibody reaction against cobalt, and the respiratory symptom of attacks of reversible dyspnoea with wheeze (asthmatic symptoms). RESULTS: Univariate analysis showed that the prevalence of the asthmatic symptoms was significantly higher in formerly and currently exposed male workers than in non-exposed male workers. Positive IgE reaction against cobalt was found in seven men (2.0%), all of whom had asthmatic symptoms. Furthermore, it was found that atopy, positive IgE antibody against cobalt, and age of 40 or older were significantly correlated with asthmatic symptoms. Multilogistic analysis on the same factors and smoking in all of the workers showed that the age, experience of hard metal exposure, and atopy were significant risk factors associated with the asthmatic symptoms. Multilogistic analysis of data for currently exposed and non-exposed workers also showed that age and atopy were risk factors, and that the exposure to cobalt at the low concentration (at or below 50 micrograms/m3) but not at the higher concentration was a significant risk factor. Exposure to mist of coolants containing ionic cobalt, used during grinding, was not found to be any more hazardous in terms of onset of asthmatic symptoms than exposure to hard metal dust containing metallic cobalt. CONCLUSIONS: Accordingly, it is concluded that both environmental factors and individual susceptibility should be taken into consideration in efforts to reduce the prevalence of hard metal asthma.

Adolescent↗
PubMed2005

Effects of hardness, chloride, and acclimation on the acute toxicity of sulfate to freshwater invertebrates.

The acute toxicity of sulfate to Ceriodaphnia dubia, Chironomus tentans, Hyalella azteca, and Sphaerium simile was assessed to support potential updates of Illinois (USA) sulfate criteria for the protection of aquatic life. The mean lethal concentrations to 50% of a sample population (LC50s), expressed as mg S04(-2)/L, in moderately hard reconstituted water (MHRW) were as follows: 512 mg/L for H. azteca, 2,050 mg/L for C. dubia, 2,078 mg/L for S. simile, and 14,134 mg/L for C. tentans. At constant sulfate (approximately 2,800 mg/L) and hardness (106 mg/L), survival of H. azteca was positively correlated with chloride concentration. Hardness also was found to ameliorate sodium sulfate toxicity to C. dubia and H. azteca, with LC50s for C. dubia increasing from 2,050 mg SO4(-2)/L at hardness = 90 mg/L to 3,516 mg SO4(-2)/L at hardness = 484 mg/L. Using a reformulated MHRW with a similar hardness but higher chloride concentration and different calcium to magnesium ratio than that in standard MHRW, the mean LC50 for H. azteca increased to 2,855 mg/L, and the LC50 for C. dubia increased to 2,526 mg/L. Acclimation of C. dubia to 500 and 1,000 mg SO4(-2)/L for several generations nominally increased mean LC50 values compared with those cultured in standard MHRW.

Animals↗
PubMed2004

A technique for standardized evaluation of soft and hard peri-implant tissues in partially edentulous patients.

BACKGROUND: There is a growing need to evaluate the esthetics of implant-supported crowns and bridges. An important tool for such an evaluation is standardized assessment of the soft and hard peri-implant tissue levels. METHODS: A simple acrylic device has been developed for reliable and reproducible assessment of soft and hard peri-implant tissues using standardized color slides and standardized dental x-rays. With this device, changes in both the soft and hard tissues around implant-supported crowns can be evaluated as a function of time. The reproducibility of the technique was tested on color slides as well as on dental x-rays in a series of implant-supported crowns and their neighboring teeth. RESULTS: The reproducibility of this technique was excellent. The measuring errors for repeated measurements of the soft and hard tissues were 0.14 +/- 0.02 mm and 0.13 +/- 0.01 mm, respectively. CONCLUSIONS: The device is a reliable tool to assess changes in both soft and hard tissues around crowns and implants over time. Likewise, it is suggested that this technique also can be used to objectively assess soft and hard tissue changes around natural teeth with or without prosthetic restorations.

Acrylic Resins↗
PubMed2006

MRI of meniscal lesions: soft-copy (PACS) and hard-copy evaluation versus reviewer experience.

OBJECTIVE: The purpose of our study was to compare diagnostic performance, reviewer confidence, and time requirements in the MRI diagnosis of meniscal tears for three types of reviewers and two types of image documentations (PACS vs hard copies). MATERIALS AND METHODS: An experienced musculoskeletal radiologist (reviewer 1), a fellow in musculoskeletal radiology (reviewer 2), and a junior staff member in orthopedic surgery (reviewer 3) evaluated MR images displayed on PACS monitors and hard copies independently and in a blinded fashion with regard to the presence or absence of meniscal tears. Seventy-one patients (mean age, 45.4 years; range, 16-80 years) were consecutively included if they had undergone both MRI of the knee and arthroscopy within 4 months. Arthroscopy was the standard of reference. Evaluation time and the reviewer's confidence in his or her diagnosis (Visual Analogue Scale, possible values of 0-100) were determined. RESULTS: Accuracies, sensitivities, and specificities in diagnosing meniscal tears were 80-87%, 63-85%, and 87-93% for soft copies and 82-85%, 64-76%, and 87-94.0%, respectively, for hard copies. Intrareviewer differences between PACS and hard copies were not significant for any of the three reviewers (McNemar tests). Reviewer 3 was less sensitive but more specific in the diagnosis of meniscal tears than reviewers 1 and 2. This difference was significant for both the PACS and hard copies. The reviewers' confidence in their diagnoses and evaluation times were not significantly different for PACS and hard copies (analysis of variance with Bonferroni post hoc analysis). CONCLUSION: Differences in the diagnostic performance of suspected meniscal tears depend on reviewer experience rather than on the type of documentation.

Adolescent↗
PubMed2003

Ecologic study of water hardness and cerebrovascular mortality in Japan.

Elevated levels of water hardness have been associated with reduced mortality from cardiovascular and cerebrovascular diseases. In this ecologic study, the authors examined the relationship between water hardness and cerebrovascular mortality in the 44 municipalities of Osaka Prefecture, Japan. Data on cerebrovascular death rates and water hardness in each municipality were obtained from public records; information on socioeconomic and health-care status in each municipality was incorporated with multiple logistic-regression analysis. The authors were unable to substantiate an inverse association of water hardness with cerebrovascular mortality--although the adjusted odds ratio in which the highest vs. lowest tertiles of water hardness were compared was 0.90 (95% confidence interval = 0.79, 1.02) in females. In addition, the difference between the sexes was not significant. In summary, the authors found no evidence that water hardness protected against cerebrovascular mortality.

Adolescent↗
PubMed1976

Distribution of glands in the mucosa of the hard palate and its relation to carcinoma.

Carcinoma of the hard palate in women who practice reverse smoking is very common in Visakhapatnam. This carcinoma usually occurs in the middle of the posterior half of the hard palate and not in the soft palate or in the anterior half of hard palate. The volume of the glandular tissue in the mucosa of the hard palate is maximum to the right or left half of the midline in the posterior half in both fetuses and adults. The localization of the carcinoma of the hard palate in reverse smokers corresponds to the glandular area of the mucosa of the hard palate.

Adult↗
PubMed2001

Macular edema and retinal hard exudates in African Americans with type 1 diabetes: the New Jersey 725.

OBJECTIVE: To determine frequency and associated risk factors for macular edema and retinal hard exudates in hospitalized African Americans with type 1 diabetes. SUBJECTS AND METHODS: Included were 725 African Americans with type 1 diabetes who participated in the New Jersey 725. Clinical evaluations consisted of a structured clinical interview, ocular examination, stereoscopic fundus photographs, and blood pressure measurements. Presence of macular edema and hard exudates was determined via masked grading of fundus photographs. Biological evaluations included blood and urine assays. RESULTS: Of the 725 patients, 89 (12.3%) had macular edema and 149 (20.6%) had retinal hard exudates in at least 1 eye. The presence of macular edema and hard exudates was significantly associated with older age at examination, longer duration of diabetes, and severity of diabetic retinopathy. Presence of proteinuria, missing insulin injections at least once a week, and longer duration of diabetes were significantly and independently associated with macular edema. Presence of proteinuria, male sex, higher low-density lipoprotein cholesterol levels, and longer duration of diabetes were significantly and independently associated with severity of retinal hard exudates. CONCLUSION: Macular edema and hard exudates are common in African Americans with type 1 diabetes, particularly in patients with evidence of renal disease.

Adolescent↗
PubMed2002

[Surgical removal of subfoveal hard exudates in diabetic maculopathy].

PURPOSE: To examine the efficacy of surgical removal of subfoveal hard exudates during surgery in diabetic maculopathy. PATIENTS AND METHODS: This study was done on 60 patients (66 eyes) that all underwent surgical removal of subfoveal hard exudates under the same surgeon. Thirty-two men (37 eyes) and 28 women (29 eyes) were included in this study. The average age of the patients was 60 years (range, 30-77 years). The average follow-up period was 21 months (range, 12-48 months). All eyes were classified into 3 groups: 13 postoperative massive type eyes, 31 massive type eyes, and 22 scatter type eyes. We evaluated the visual results of these types. RESULTS: Preoperative and postoperative mean visual acuity was as follows: postoperative massive type 0.11, 0.22, massive type 0.12, 0.29, and scatter type 0.19, 0.33. Postoperatively visual acuity improved significantly in all types. There were no subfoveal hard exudates postoperatively in any eyes. CONCLUSION: Surgical removal of massive subfoveal hard exudates is effective, but its effects on vision are limited. Surgical removal of deposited subfoveal hard exudates may prevent massive subfoveal hard exudates postoperatively and improve visual prognosis.

Adult↗
PubMed2003

[Physicochemical changes in starch during corn alkaline-cooking in varieties with different kernel hardness].

Changes in starch characteristics caused by alkaline-cooking in two corn genotypes (hard and soft) were studied in the present work. Color, pH, pasting properties (Brabender viscoamylograph), water sorption, solubility, swelling power and thermal analysis (Differential scanning calorimetry) were determined in starches previously extracted, from raw and alkaline-cooked hard and soft corns. A reduction in maximum viscosity peak, temperature at the endothermic peak and swelling power at 90 degrees C, and an increase in solubility was observed in starches obtained from both hard and soft corn after alkaline-cooking. Starch from hard corn showed an increment in initial pasting temperature after alkaline-cooking. Alkaline-cooking induced higher modifications in hard than in soft corn starch, probably as a result of its endosperm type and grain hardness, although optimum cooking times were used for each corn genotype.

Edible Grain↗
PubMedDate not supplied

Hard-copy versus soft-copy image reading for detection of ureteral stones on abdominal radiography.

PURPOSE: The purpose of this study was to compare the usefulness of soft-copy images displayed on a cathode ray tube (CRT) with hard-copy images (film images) for detecting ureteral stones on abdominal radiography. MATERIALS AND METHODS: Five radiologists read images from 50 cases of ureteral stones and 50 normal cases diagnosed on the basis of intravenous urography and CT. For hard-copy reading, 10-bit images at 3,520x4,280 pixels obtained by computed radiography were printed on 14x17-inch films. For soft-copy reading, 8-bit images were displayed on a 17-inch monochrome monitor at 1,024x1,280 pixels. The study items were area under receiver operating characteristics (ROC) curve (Az), ureteral stone detection sensitivity and specificity, and reading time. RESULTS: For soft-copy and hard-copy images, the average Az values were 0.855 and 0.851, sensitivity was 62.8% and 62%, and specificity was 70.8% and 62.4%, respectively. There were no statistically significant differences between these values. Reading time was 106.6 min for soft-copy images, significantly longer than the 71.2 min for hard-copy images (p<0.05). CONCLUSION: Although soft-copy image reading time was longer than hard-copy image reading time, the ability to diagnose ureteral stones on abdominal radiography did not differ for soft- and hard-copy images.

Adolescent↗
PubMed2004

Effect of water hardness on oocyte quality and embryo development in the African clawed frog (Xenopus laevis).

Husbandry and health of the African clawed frog, Xenopus laevis, greatly influences the quality of oocytes produced. One factor affecting oocyte quality is the water conditions in which females are maintained. Dechlorination and adequate salt concentration are known to affect oocytes, but water hardness has not been considered an important factor in Xenopus husbandry by the research community. We found that, when females were kept in soft water or water with marine salts alone, even when it was cooled to 17 to 18 degrees C, the quality of oocytes decreased; only 20 to 25% of resulting embryos developed to tailbud stages. Survival and normal development of embryos increased significantly within one month of addition to the laboratory housing water of salts that mimic conditions in African Rift Valley lakes. These salts greatly increased water hardness; development of embryos to tailbud stages remained high (50 to 70% on average) for more than a year after their addition to the water housing females. Water from South African ponds where X. laevis are collected, and from wells used by the major suppliers of X. laevis, also was moderately to very hard. Our results suggest that X. laevis is naturally adapted to hard water, and indicate that increasing general hardness during laboratory housing is more important for oocyte quality and embryo development than is increasing carbonate hardness (alkalinity) in the water used to house females.

Africa↗
PubMed2006

[Analysis on differences between soft-tissue and hard-tissue profile in malocclusions].

OBJECTIVE: To study the characteristics of soft-tissue integument and the differences between soft-tissue and hard-tissue topography in malocclusions. METHODS: 144 female patients, 12-15 years old, were selected. They were divided into class I, class II and class III groups according to the value of angle ANB which was measured on the pre-treatment cephalographs. Each group had 48 patients. Each patient had same type of skeletal pattern and occlusal pattern, full set of permanent teeth and none of cranofacial soft-tissue and hard-tissue diseases. 4 pairs of measurements describing soft-tissue and hard-tissue sagittal facial pattern and the prominence of lips and incisors were measured on each cephalograph. They were angle SnNsB', angle ANB, angle NsSnPos, angleNAPo, UL-SnPos, UI-APo, LL-SnPos and LI-APo. The distribution of soft-tissue sagittal facial pattern in each skeletal group was analyzed. The differences between angle SnNsB' and angle ANB, angle NsSnPos and angle NAPo, UL-SnPos and UI-APo, LL-SnPos and LI-APo were calculated in each patient. Then we calculated the means and the ranges of these differences in each group, the probability of positive and negative difference between each pair of measurements in each group were calculated too. Chi2 test on those probabilities were performed between the three groups. The mean difference between each pair of measurements was then analyzed by ANOVA between the three groups. RESULTS: The disharmony between soft-tissue and hard-tissue sagittal facial pattern was found in 20%-30% of malocclusion patients. There were more or less differences between soft-tissue and hard-tissue topography and the ranges of their variation were quite wide. The soft-tissue integument increasingly tended to augment the convexity of soft-tissue facial profile when skeletal pattern varied from class II to class I to class III, at the same time, tended to increase upper lip prominence and decrease lower lip prominence. CONCLUSION: On the average, soft-tissue integument tends to camouflage the abnormality of hard-tissue topography. But as to individual, the relative independence of soft-tissue integument makes it important to notice the influence of soft tissue on treatment planning and results.

Cephalometry↗
PubMed2006

Acute toxicity of mercury to the fingerlings of Indian major carps (catla, rohu and mrigal) in relation to water hardness and temperature.

In the present study short-term (96 hr) toxicity of mercury in relation to water hardness (270 and 560 mg/l) and temperature (16 degrees C and 35 degrees C) to the fingerlings of Indian major carps, i.e. catla, rohu and mrigal has been evaluated using static bioassay. The LC5o indicates that both water hardness and temperature played significant role in mercury toxicity. The test fishes were found most resistant with water hardness of 560 mg/l at 16 degrees C as compared to that of water hardness of 560 mg/l at 35 degrees C and water hardness of 270 mg/l at both the temperatures, i.e. 35 and 16 degrees C. Whereas the order of relative sensitivities of these fishes for mercury ions were recorded as catla>rohu>mrigal. The safe concentrations of mercury were ranged in between 12.133 to 19.689 microg/l for catla; 64.039 to 82.555 microg/l for rohu and 73.510 to 89.585 microg/l for mrigal for both the water hardness and temperature.

Animals↗