Evaluating the coating process of titanium dioxide nanoparticles and sodium tripolyphosphate on cucumbers under chilling condition to extend the shelf-life.

Cucumber is a highly perishable fruit, that can easily suffer from water loss, condensation, shriveling, yellowing and decay. The present investigation aim was to extending the shelf-life of cucumber using eco-friendly sodium tripolyphosphate and nano-material. Decay; hardness; succinate dehydrogenase activity (SDH); condensation and shriveling rates; and visual quality assessments of cucumbers fruits were evaluated during 21 days of storage period at 10 °C. There was a slight incidence of decay among (Chitosan/Titanium Dioxide Nanoparticles) CS-TiO2 and (Chitosan/Titanium Dioxide Nanoparticles/Sodium Tripolyphosphate) CS-TiO2-STP samples, which reported the lowest decay incidence 2.21% in CS-TiO2, while CS-TiO2-STP did not show any decay at end of storage period. CS-TiO2-STP recorded the lowest value in SDH activity 0.08 ∆OD min-1 mg protein-1. Very slight hardness, water condensation, and shriveling were detected in CS-TiO2 samples, while CS-TiO2-STP was the lowest compared with other SC samples and control. In general, CS-TiO2-STP treatment was found most potential to enhance the postharvest shelf life of cucumber throughout the storage period up to 21 day.

Improve the performance of coated cemented hip stem through the advanced composite materials.

Design of hip joint implant using functionally graded material (FGM) (advanced composite material) has been used before through few researches. It gives great results regarding the stress distribution along the implant and bone interfaces. However, coating of orthopaedic implants has been widely investigated through many researches. The effect of using advanced composite stem material, which mean by functionally graded stem material, in the total hip replacement coated with the most common coated materials has not been studied yet. Therefore, this study investigates the effect of utilizing these two concepts together; FGM and coating, in designing new stem material. It is concluded that the optimal FGM cemented stem is consisting from titanium at the upper stem layers graded to collagen at a lower stem layers. This optimal graded stem coated with hydroxyapatite found to reduce stress shielding by 57% compared to homogenous titanium stem coated with hydroxyapatite. However, the optimal functionally graded stem coated with collagen reduced the stress shielding by 51% compared to homogenous titanium stem coated with collagen.

A new design of cemented stem using functionally graded materials (FGM).

One of the most frequent complications of total hip replacement (THR) is aseptic loosening of femoral component which is primarily due to changes of post-operative stress distribution pattern with respect to intact femur. Stress shielding of the femur is known to be a principal factor in aseptic loosening of hip replacements. Many designers show that a stiff stem shields the surrounding bone from mechanical loading causing stress shielding. Others show that reducing stem stiffness promotes higher proximal interface shear stress which increases the risk of proximal interface failure. Therefore, the task of this investigation is to solve these conflicting problems appeared in the cemented total hip replacement. The finite element method and optimization technique are used in order to find the optimal stem material which gives the optimal available stress distribution between the proximal medial femoral bone and the cement mantle interfaces. The stem is designed using the concept of functionally graded material (FGM) instead of using the conventional most common used stem material. The results showed that there are four feasible solutions from the optimization runs. The best of these designs is to use a cemented stem graded from titanium at the upper stem layer to collagen at the lower stem layer. This new cemented stem design completely eliminates the stress shielding problem at the proximal medial femoral region. The stress shielding using the cemented functionally graded stem is reduced by 98% compared to titanium stem.

Sonography of the knee joint().

The aim of this article is to review the sonographic appearances of common disorders involving the knee joint. Ultrasound is a sensitive method for diagnosis of tendon injuries. Injured ligaments appear swollen with mixed echogenicity. Meniscal injuries and muscle tears can be easily diagnosed. Ultrasound shows synovial thickening and effusion in inflammatory arthropathy and erosions of the articular surface in degenerative arthritis. It can be used effectively in the detection of rheumatoid arthritic activity and for grading degenerative arthritis lesions. Cystic lesions, as well as benign and malignant soft-tissue masses, are clearly delineated. Ultrasound is a safe noninvasive imaging modality that can be used for diagnosis of different disorders involving the knee joint.

Improved design of cementless hip stems using two-dimensional functionally graded materials.

Increasingly, it is acknowledged that bone resorption around cementless hip implants may cause future problems. The solution is frequently sought in reducing implant stiffness. However, this confronts the designer with a true design conflict: how to reduce the stiffness without excessively loading the proximal bone/prosthesis interface? The aim of this work is to improve the design of cementless hip stem material, using two-dimensional (2D) functionally graded material (FGM) concept in order to solve the above problems. Two models were used in this analysis, using three materials with different elastic moduli, E(1), E(2), and E(3). In model I, the elastic moduli E(1) and E(2) gradually change along the upper stem surface, while E(3) is maintained constant along all the lower surface of the stem. However, in model II, the elastic moduli E(1) and E(2) gradually change along the lower stem surface, while E(3) is maintained constant all along the upper stem surface. It is found that the recommended model is model I, which has three distinct materials of hydroxyapatite, Bioglass, and collagen. The recommended design of 2D FGM is expected to reduce the stress shielding by 91% and 12%, respectively, compared with titanium stem and model II of FGM. It is found that this new design reduces the maximum interface shear stress at the lateral and medial sides of the femur by about 50%, compared with titanium stem. Furthermore, the maximum interface shear stress is reduced by about 17% and 11% at the lateral and medial sides of the femur, respectively, compared with that of model II of FGM.

Design optimization of cementless metal-backed cup prostheses using the concept of functionally graded material.

Metal backing has been widely used in acetabular cup design. A stiff backing for a polyethylene liner was initially believed to be mechanically favourable. Yet, recent studies of the load transfer around acetabular cups have shown that a stiff backing causes two problems. It generates higher stress peaks around the acetabular rim than those caused by full polyethylene cups and reduces the stresses transferred to the dome of the acetabulum causing stress shielding. The aim of this study is to overcome these two problems by improving the design of cementless metal-backed acetabular cups using the two-dimensional functionally graded material (FGM) concept through finite-element analysis and optimization techniques. It is found that the optimal 2D FGM model must have three bioactive materials of hydroxyapatite, Bioglass and collagen. This optimal material reduces the stress shielding at the dome of the acetabulum by 40% and 37% compared with stainless steel and titanium metal backing shells, respectively. In addition, using the 2D FGM model reduces the maximum interface shear stress in the bone by 31% compared to the titanium metal backing shell.

Shape optimization of metal backing for cemented acetabular cup.

Stresses are generated in implant materials and bone, and at their interfaces. These stresses may affect the structural properties of the implant/bone system, or bring it to failure at some time in the postoperative period. Due to these stresses, acetabular cup loosening becomes an important problem for long term survival of total hip arthroplasty. It was found that metal backing would tend to reduce stresses in the underlying acrylic cement and bone. Yet, recent studies of load transfer around acetabular cups have shown that metal backing generates higher stress peaks in cement at the cup edges, while generates lower stress peaks in bone at the central part of acetabulum (dome), thus the bone at the dome becomes more stress shielded. In this study a numerical shape optimization procedure in combination with an axisymmetric finite element model was used in order to optimize the shape of a stainless steel metal backing shell. The design was to minimize fatigue notch factor in cement along cement/bone and cement/metal backing interfaces in order to prevent failure of cement mantel and loosening of acetabular components, at the same time increasing fatigue notch factor in bone at the center of acetabulum to prevent stress shielding. The results of this study indicate that cemented acetabular cup designs can be improved by using metal backing shells of non-uniform thickness, thick at the dome and thin at edges. Fatigue notch factor in cement was reduced by 2.3% at cement/metal backing interface and increased by 1.3% in the central bone of acetabulum. Von Mises stresses in the cement edge were reduced by 17.8% and 19.3% along cement/bone and cement/metal backing interfaces, respectively. Thus the optimal design will reduce the possibility of fatigue fracture of cement and decrease the stress shielding effect and the likely incidence of bone resorption, whereby extend the expected life of the prostheses.

The effect of elastic modulus of the backing material on the fatigue notch factor and stress.

In cemented acetabular cup design it is acknowledged that bone resorption and fatigue fracture of cement may cause the most common problems after total hip replacement. Previous studies have optimized the shape of metal backing (MB) shell used in cemented acetabular components in order to minimize the fatigue notch factor (Kf) in cement, whilst at the same time maximizing Kf in bone at the central part of acetabulum to prevent stress shielding and subsequent bone resorption [1]. The optimal shape was found to be thin at the edges and thick at the dome. The present study describes the effect of changing the elastic modulus of the backing material on Kf and stresses as predicted by the initial shape of the backing shell of (3 mm) thick, and the optimized backing shape of non-uniform thickness in order to find the optimal material for the backing shell. It is recommended to use a backing shell material with elastic modulus equals 70 GPa (which can be readily attained using a fiber reinforced polymer composite). It is shown that such a material will decrease the fatigue notch factor and the stresses in cement at cup edges, at the same time it will increase the stresses and the fatigue notch factor in bone at the central part of acetabulum. Thereby, reducing the possibility of fatigue fracture of cement, whilst at the same time decreasing the stress shielding effect and the resulting bone resorption. The effect of lower bone resorption and lower probability of fatigue fracture of the cement will also reduce the incidence of loosening and premature revision operations.

[MRI in typical and atypical aortic dissection]. / MRT bei typischer und atypischer Aortendissektion.

PURPOSE: To determine the value of MRI in typical and atypical aortic dissections. METHODS: MRI investigations on 16 patients with aortic dissections were analysed retrospectively; for 8 patients CT investigations carried out at almost the same time were available for comparison. RESULTS: In all cases the diagnosis of aortic dissection was possible from MRI and CT. If a dissection membrane and a double lumen were present these were detected in all patients by both methods. In three patients with atypical dissections, only an asymmetrical abnormal wall thickening as sole sign for the presence of an aortic dissection was seen. A differentiation between true and false lumen was possible in 16 of 17 MRI investigations and in 5 of 8 CT investigations on the basis of differing blood flow velocities or, respectively, the detection of a thrombus in the false lumen. The relationship of the dissection membrane to the large aortic branches as well as the determination of the branch vessel origin with regard to true or false lumen could be evaluated better with MRI than with CT. CONCLUSIONS: Thus MRI has a significant role in the diagnosis and follow-up of aortic dissections. The advantage in comparison to the alternative spiral CT technique is, in addition to the absence of radiation exposure, the better analysis of the extent of the dissection as a result of the multi-planar slice orientation (especially in the region of the aortic arch and the arch vessel origins) without the necessity to administer iodine-containing contrast media.

Diagnosis of pulmonary metastases with turbo-SE MR imaging.

The sensitivity of MR imaging for detection of pulmonary metastases was evaluated in 23 patients. The MR imaging was performed with T2-weighted turbo-spin-echo (TSE) sequences at 1.5 T. The MR images were compared with spiral volumetric CT which served as the radiological standard. All MR images were interpreted by two radiologists without knowledge of CT findings. The MR imaging technique initially enabled correct identification of altogether 286 of 340 metastases (84 %) resulting in sensitivities of 36 % (size of nodules < 5 mm), 83 % (size of nodules 5-10 mm), 92 % (size of nodules 10-15 mm), and 100 % (size of nodules > 15 mm). Retrospectively with knowledge of CT findings an additional 39 metastases were visible; 15 remained undetected even retrospectively. The results of this paper suggest that MRI still does not have a role for screening for pulmonary metastases. It proves, however, that the incidental diagnosis of a pulmonary lesion on T2-weighted TSE images is highly reliable in representing a pulmonary nodule also visible on CT. However, thus far the malignant nature especially of small nodules detected by MRI (as by CT) remains uncertain even in patients with known malignant neoplasm.

Distribution of protein kinase C alpha and accumulation of extracellular Ca2+ during early dentin and enamel formation.

Activation of the protein kinase C (PKC)-related signal transduction system has been associated with phenotypic expression in a wide variety of cell types. In in vitro studies, it has often been activated by relatively small increases in the Ca2+ concentration ([Ca2+]) in the medium. The studies reported here explored the hypothesis that localized increases in the extracellular [Ca2+] and activation of the PKC-related pathway may be involved in early dentin and enamel formation. Whole-head, freeze-dried sections through the developing molars of 5-day-old rats were evaluated by methods that localized non-crystalline Ca2+. Immunohistochemical methods were adapted for use with the freeze-dried sections, and two monoclonal antibodies were used to localize PKC alpha in the formative cells of the developing teeth. Low concentrations of extracellular Ca2+ were observed in the early, unmineralized dentin in the area of ameloblast differentiation. Increased concentrations occurred at the point of initial dentin mineralization, immediately before the beginning of enamel matrix deposition. PKC alpha was localized in the differentiating odontoblasts, at the beginning of dentin matrix deposition. It was intensely localized in the distal borders of the pre-ameloblasts, and appeared to redistribute in the cells during ameloblast differentiation. These observations suggest that local increases in the extracellular [Ca2+] and the PKC signal transduction pathway may be involved in key inductions in the early stages of dentin and enamel formation.

Effects of phosphonoformic acid and 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) on distribution of tetracycline in the developing rat molar.

Tetracycline was used as a marker to study the effect of phosphonoformic acid and 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) on the mineralization of the developing dental hard tissues. Groups of young rats were given a single subcutaneous injection of tetracycline and at the same time were injected with a single dose of either phosphonoformic acid or HEBP (10 mg P/kg b.w.). Alternatively, rats were injected with the tetracycline after different time intervals from the phosphonate injection. Rats were sacrificed at intervals ranging from 1 to 4 days. Frozen-sections were obtained at the level of the maxillary first molar and prepared for light and fluorescence microscopy. The results of the present study indicate that the distribution pattern of tetracycline in the developing dental hard tissues is greatly affected by the pathologic changes induced by phosphonoformic acid and HEBP. Both drugs caused similar changes in the pattern of tetracycline uptake in the developing enamel. There seems to be a direct relation between the presence of developmental defects of enamel and the degree of discoloration induced by tetracycline. Aberrations in the mineralization of dentin were caused only by HEBP. As demonstrated by this study, HEBP is capable of inducing a provisional inhibitory effect on dentin mineralization.

Mineralization disturbances of the developing rat molar induced by mono- and bisphosphonates.

Morphological changes have been reported previously in the developing dental tissues of the rat molar following administration of mono- or bisphosphonates. However, few studies have been published on the relationship between these and the possible mineralization disturbances. Two monophosphonates, phosphonoformic and phosphonoacetic acids, and two bisphosphonates, dichloromethylene bisphosphonate (Cl2MBP) and 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) in a dosage of 10-30 mg P/kg b.w. were injected in 5 day old rats and the induced changes analyzed by microradiographic and histologic examination. A single injection of mono- or bisphosphonates resulted in apparently identical disturbances of the developing enamel associated with subameloblastic cysts. Three different types of cysts were distinguished. In type 1 cysts, enamel hypoplasia near the cusp tip with an outer highly mineralized zone associated with calcified deposits in the cystic lining and inner hypomineralized enamel were discerned. The type 2 cysts were characterized by the formation of a thick enamel layer in the cervical area and deep in the fissures due to the development of internal enamel defects. The type 3 cysts were seen in the cervical area of the mesial or distal sides of the tooth without any remarkable changes in the underlying enamel matrix. Both Cl2MBP and HEBP induced two demarcation lines in the dentin layer. Additionally, HEBP resulted in the formation of niche-like defects of unmineralized dentin which healed by mineral deposition from the periphery. From these results, it can be concluded that mono- and bisphosphonates have similar effects on enamel mineralization and the type of response depends on the stage of enamel matrix secretion while bisphosphonates, in addition, interfere with the dentin mineralization.

Developmental disturbances of the rat molar induced by two diphosphonates.

Very few reports have been published about the effects of diphosphonates on the cells and tissues of developing teeth. The present study was designed to investigate possible morphological changes in ameloblasts and odontoblasts and relate these changes to defects in the enamel surface of erupted teeth. Young rats were injected subcutaneously with single or multiple doses of HEDP or Cl2MDP (10 mg P/kg b.w.). Light microscopic examination of developing maxillary first molars showed that single injections of HEDP or Cl2MDP induced subameloblastic cysts between the secretory ameloblasts and the developing enamel. The ameloblastic lining of the cysts contained numerous calcified deposits. A few days after injection, hypoplasias were seen in the enamel in areas previously occupied by cysts. In the erupted teeth, scanning electron microscopic examination revealed enamel hypoplasias which were mainly localized on the mesial sides of the cusps. In addition to the previously mentioned disturbances, multiple injections resulted in more extensive cysts, some of which contained non-mineralized enamel matrix. Inhibition of the mineralization of dentin and alveolar bone was also noticed.

Effects of phosphonoformic and phosphonoacetic acids on developing enamel of rat molars.

The effect of a single subcutaneous injection of different dosages of phosphonoformic or phosphonoacetic acid on the developing dental tissues of the rat molar was studied. The substances were injected at different rat ages and effects on the developing teeth were analyzed by means of histochemistry of frozen sections and scanning electron microscopy. Molars of rats injected at the age of 10 or 15 days showed no pathologic changes. Administration of phosphonoacetic acid in a dosage of 10 or 20 mg P/kg b.w. had no demonstrable effect on the dental tissues in any of the animals. Phosphonoformic or phosphonoacetic acid in a dosage of 10 or 30 mg P/kg b.w. respectively induced subameloblastic cysts 24 h after injection to 4-7-day-old rats. The cysts were mainly localized on the mesial sides of the cusps under ameloblasts in the late secretory stage. Calcified depositions were seen in the ameloblastic layer lining the cystic cavities. A thin zone, the staining of which indicated a high mineral content, was seen in the outermost enamel layer under the cysts. A few days later, enamel hypoplasias were seen in areas previously occupied by cysts. A lightly stained line was observed in the enamel matrix demarcating the amount of enamel matrix formed before and after the injection. Hypoplastic lesions were also noted in the enamel surface of newly erupted molars. These findings suggest that the two injected monophosphonates can induce pathologic changes in the developing enamel organ and hypoplasias in the enamel.

Characterization of human salivary beta-N-acetyl-D-glucosaminidase (NAGase).

NAGase activity was studied in mixed whole, parotid, and submandibular saliva. The maximum activity of NAGase was found to be at pH 5.0. NAGase activity varied considerably among the subjects. The data indicated that a large portion of NAGase activity originates from oral microorganisms. NAGase activity was greatly reduced after heating for 45 min at 50 degrees C. The residual activity after storage at -20 degrees C was higher than the original activity. The enzyme activity was markedly diminished after the addition of Sn++ and Ag+ ions, while no activity was detected after the addition of Hg+ ion.

beta-N-acetyl-D-glucosaminidase (NAGase) and lysozyme activity in human parotid and submandibular saliva.

beta-N-acetyl-D-glucosaminidase (NAGase) and lysozyme activity were studied in isolated parotid and submandibular saliva collected from five healthy individuals over a 3-wk period. During the first week, saliva samples were collected three times within one specified day (9 a.m., noon, 4 p.m.). Then for each of the following 2 wk, saliva was collected at 9 a.m. of the same day. NAGase activity was determined spectrophotometrically by using p-nitrophenyl-glycoside as substrate. Lysozyme activity was determined turbidimetrically by using Micrococcus lysodeikticus cells as substrate. NAGase and lysozyme were present in all samples of parotid and submandibular saliva. NAGase activity was generally higher in saliva samples collected in the morning and decreased during the day. There was considerable variation in NAGase activity and almost no variation in lysozyme activity in samples taken from the same person. NAGase activity was higher in parotid than in submandibular saliva while lysozyme activity was somewhat higher in submandibular saliva.