Autofocusing for automated microscopic evaluation of blood smear and pap smear

Autofocusing is a fundamental procedure towards automated microscopic evaluation of blood smear and pap smear samples for clinical diagnosis. This paper presents comparison results of 16 focus algorithms based on a total of 8000 bright-field images from 10 blood smear and pap smear samples. A ranking methodology adapted from our previously proposed ranking system is used for thoroughly evaluating the performance of the selected 16 focus algorithms. Experimental results demonstrate that the variance algorithm provides the best overall performance, which will be selected for our future implementation of an automated microscopic system for computer-assisted blood smear and pap smear evaluation. Together with our previously reported findings, we hypothesize that the variance algorithm or the Normalized variance algorithm is the optimal focus algorithm for all non- fluorescence microscopy applications.

Effect of protein on biohydrogen production from starch of food waste

This study demonstrated the influence of protein on biohydrogen production from carbohydrates, especially starch, by using different combinations of two model food wastes, rice as starch-rich and soybean residue as protein-rich food waste. It was found the maximum specific hydrogen production potential, 0.99 mol H2/mol initial starch as glucose, and the maximum specific hydrogen production rate, 530 ml H2/h g-VS, occurred at a starch/protein ratio of 1.7. The protein content in the initial food waste not only provided buffering capacity to neutralize the volatile fatty acids as concurrent products but also enhanced the hydrogen production by providing readily available organic nitrogen such as soluble proteins and amino acids to microorganisms.

Digestion of frozen/thawed food waste in the hybrid anaerobic solid-liquid system

The hybrid anaerobic solid-liquid (HASL) system, which is a modified two-phase anaerobic digester, is to be used in an industrial scale operation to minimize disposal of food waste at incineration plants in Singapore. The aim of the present research was to evaluate freezing/thawing of food waste as a pre-treatment for its anaerobic digestion in the HASL system. The hydrolytic and fermentation processes in the acidogenic reactor were enhanced when food waste was frozen for 24h at -20 degrees C and then thawed for 12h at 25 degrees C (experiment) in comparison with fresh food waste (control). The highest dissolved COD concentrations in the leachate from the acidogenic reactors were 16.9 g/l on day 3 in the control and 18.9 g/l on day 1 in the experiment. The highest VFA concentrations in the leachate from the acidogenic reactors were 11.7 g/l on day 3 in the control and 17.0 g/l on day 1 in the experiment. The same volume of methane was produced during 12 days in the control and 7 days in the experiment. It gave the opportunity to diminish operational time of batch process by 42%. The effect of freezing/thawing of food waste as pre-treatment for its anaerobic digestion in the HASL system was comparable with that of thermal pre-treatment of food waste at 150 degrees C for 1h. However, estimation of energy required either to heat the suspended food waste to 150 degrees C or to freeze the same quantity of food waste to -20 degrees C showed that freezing pre-treatment consumes about 3 times less energy than thermal pre-treatment.

Enhancement of food waste digestion in the hybrid anaerobic solid-liquid system

The hybrid anaerobic solid-liquid (HASL) system is a modified two-phase anaerobic digester for food waste treatment. To enhance the performance of anaerobic digestion in the HASL system, thermal pre-treatment (heating at 150 degrees C for 1 h) and freezing/thawing (freezing for 24 h at-20 degrees C and then thawing for 12 h at 25 degrees C) were proposed for food waste pre-treatment before the anaerobic digestion. Both processes were able to alter the characteristics and structure of food waste favoring substance solubilization, and hence production of methane. However, there was no net energy gain when the energy required by the pre-treatment processes was taken into account.

Robust contact detection in micromanipulation using computer vision microscopy

This paper presents a computer vision algorithm for visually detecting the contact between an end-effector and a target surface under an optical microscope. Without using additional sensors (e.g., proximity or force/touch sensors), this algorithm provides robustness and a sub-micrometer detection resolution. Fundamentally, after the establishment of a contact in the world frame, further vertical motion induces horizontal motion in the image plane. An analysis is presented to elaborate this fundamental mechanism. Experimental results demonstrate that this computer-vision-based method is capable of achieving contact detection between a micropipette and a glass slide surface with a resolution of 0.2 microm. Furthermore, 1300 experimental trials reveal that the presented algorithm is robust to variations in illumination intensity, microscopy magnification, and microrobot motion speed.

Icariin enhances the osteogenic differentiation of bone marrow stromal cells but has no effects on the differentiation of newborn calvarial osteoblasts of rats

Since the total flavonoid extract (TFE) of Epimedium herb was found to prevent osteoporosis induced by ovariectomy in rats, we have been attempting to identify the exact compound responsible for the bone-strengthening activity. In this experiment, four flavonoid extracts were obtained from Epimedium sagittatum (Siebold & Zucc.) Maxim, which contained 25.3%, 51.2%, 82.3% and 99.2% icariin respectively. They were separately supplemented into the culture media of newborn rat calvarial osteoblasts (ROB) or primary rat bone marrow stroma cells (rMSCs) at 0.1, 1, 10 and 100 microg/ml respectively, in order to observe their effects on the cells. Not any appreciable effect was found on the differentiation of ROB, but an enhancing effect on the osteogenic differentiation of rMSCs was found, and the enhancing degree was icariin-dependent, that is, a higher concentration of icariin in the extract caused more mineralized bone nodules and higher calcium deposition levels. The gene expressions involved in osteogenesis were also improved which was revealed by RT-PCR, including alkaline phosphatase, bone matrix protein (osteocalcin, osteopontin, bone sialoprotein) and cytokines (TGF-beta1 and IGF-I). The effect of icariin on cell proliferation was assayed by the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Icariin inhibited the proliferation of rMSCs and ROB when its concentration was higher than 10(-5) microM (6.7 microg/ml), no stimulative effect was found. The above results indicated that icariin may exert bone-strengthening activity by enhancing the osteogenic differentiation of MSCs, which partially explains the anti-osteoporosis action of Epimedium herb.

Surface mechanical properties, corrosion resistance, and cytocompatibility of nitrogen plasma-implanted nickel-titanium alloys: a comparative study with commonly used medical grade materials

Stainless steel and titanium alloys are the most common metallic orthopedic materials. Recently, nickel-titanium (NiTi) shape memory alloys have attracted much attention due to their shape memory effect and super-elasticity. However, this alloy consists of equal amounts of nickel and titanium, and nickel is a well known sensitizer to cause allergy or other deleterious effects in living tissues. Nickel ion leaching is correspondingly worse if the surface corrosion resistance deteriorates. We have therefore modified the NiTi surface by nitrogen plasma immersion ion implantation (PIII). The surface chemistry and corrosion resistance of the implanted samples were studied and compared with those of the untreated NiTi alloys, stainless steel, and Ti-6Al-4V alloy serving as controls. Immersion tests were carried out to investigate the extent of nickel leaching under simulated human body conditions and cytocompatibility tests were conducted using enhanced green fluorescent protein mice osteoblasts. The X-ray photoelectron spectroscopy results reveal that a thin titanium nitride (TiN) layer with higher hardness is formed on the surface after nitrogen PIII. The corrosion resistance of the implanted sample is also superior to that of the untreated NiTi and stainless steel and comparable to that of titanium alloy. The release of nickel ions is significantly reduced compared with the untreated NiTi. The sample with surface TiN exhibits the highest amount of cell proliferation whereas stainless steel fares the worst. Compared with coatings, the plasma-implanted structure does not delaminate as easily and nitrogen PIII is a viable way to improve the properties of NiTi orthopedic implants.

China-Japan enhance joint research cooperation for drug discoveries and development: News from CJMWDDT 2007 in Jinan, China

Viral hepatitis is currently a major global cause of morbidity and mortality. In some Asian countries like China and Japan, Hepatitis B and C in particular are the most common extremely infectious diseases and are likely to develop into liver cirrhosis. Furthermore, statistics indicate that patients with liver cirrhosis resulting from hepatitis B and C have an increased risk of developing hepatocellular carcinoma (HCC). Scientists have worked tirelessly to find curative therapeutic strategies to control chronic hepatitis and liver cirrhosis, accompanied by improvements in public health and living conditions. China's Shandong University and the University of Tokyo in Japan previously established a longterm cooperative relationship. Cooperative programs include co-training of postgraduates, exchanges of visiting scholars, academic symposia, and a bilateral international joint research program. Some substantive progress has been made as a result of bilateral endeavors. For instance, the Shandong University China-Japan Cooperation Center for Drug Discovery & Screening (SDU-DDSC) has enhanced to serve as an important platform for further close cooperation. At the same time, the International Advancement Center for Medicine & Health Research (IACMHR) - "Drug Discoveries and Therapeutics" and International Research and Cooperation Association for Bio & Socio-Sciences Advancement (IRCA-BSSA) - "BioScience Trends" were established (Visit http://www.ddtjournal.com and http://www.biosciencetrends.com ). The first China-Japan conference on new drug discoveries and therapeutics (CJMWDDT 2007) was recently held in Jinan, China May 27-29, 2007, which provided opportunities for further communication and cooperation and increased knowledge of new drug research and clinical cures for hepatitis. Financially supported by the National Natural Science Foundation of China (NSFC) and the Japan Society for the Promotion of Science (JSPS), the conference covered a wide range of topics in different areas of chemical biology, phytochemistry, medicinal chemistry, and pharmacology and it resulted in informed and genial discussions of hepatitis cures that yielded fruitful results. The active involvement and participation by attendees gave the conference a congenial atmosphere. In the end, an agreement was reached to work together on new drug discovery and effective hepatitis therapeutic strategies, and some agreements have resulted in the creation of handover protocols. The CJMWDDT 2007 was a highly successful scientific event that strengthened and promoted extensive cooperation between China and Japan for the development of new pharmaceutical products and hepatitis cures.

Are humoral factors involved in the colonic mucosal lesion in portal hypertensive rats?

AIMS

With a prehepatic portal hypertensive rat model, we explored the involvement of humoral factors to the occurrence of portal hypertensive colopathy (PHC), another clinical entity besides portal hypertensive gastropathy (PHG) in portal hypertension, by investigating the expression of inducible nitric oxide synthase (iNOS), endothelial constitutive NOS (ecNOS), endothelin-1 (ET-1), tumour necrosis factor alpha (TNF-alpha) and vascular endothelial growth factor (VEGF) in the colonic and gastric mucosa.

METHODS

Portal hypertension was produced by a two-stage ligation of portal vein plus ligation of the left adrenal vein in male Sprague-Dawley rats. Two weeks after complete obstruction of the portal vein, the portal pressure was measured and the expression of iNOS, ecNOS, ET-1, TNF-alpha and VEGF in the colonic and gastric mucosa were detected by RT-PCR and immunohistochemistry methods.

RESULTS

A 1.8 fold (P < 0.01) elevation of the portal pressure was detected in the portal hypertensive rats as compared to control. Significantly up-regulation of the mRNA levels of iNOS (P < 0.01), ET-1 (P < 0.05) and TNF-alpha (P < 0.01), but not ecNOS and VEGF, were detected in the colonic mucosa of portal hypertensive rats compared with control. The mRNA of iNOS, ecNOS, ET-1, TNF-alpha and VEGF were all significantly increased at varied levels in the gastric mucosa as compared to control (P all < 0.05). No difference of the appearance and localization of immunostaining of iNOS, ecNOS, ET-1, TNF-alpha and VEGF in the colonic and gastric mucosa were seen between two groups.

CONCLUSIONS

These data suggest the involvement of the upregulation of iNOS, ET-1 and TNF-alpha in the colonic mucosal lesion of portal hypertensive rats.

Dynamic evaluation of autofocusing for automated microscopic analysis of blood smear and pap smear

Autofocusing is a fundamental procedure towards automated microscopic evaluation of blood smear and pap smear samples for clinical diagnosis. This paper presents comparison results of 16 selected focus algorithms based on 8000 static bright-field images and 1600 dynamic autofocusing trials using 10 blood smear and pap smear samples. Besides static behaviour, dynamic autofocusing performance is introduced for ranking the 16 focus algorithms. The Fibonacci search algorithm is employed for controlling the z-motor of the microscope to reach the focus position that is determined by focus objective functions. Experimental results demonstrate that the variance algorithm provides the best overall performance. Together with our previously reported findings, it is demonstrated that the variance algorithm or the normalized variance algorithm is the optimal focus algorithm for non-fluorescence microscopy applications including pap smear and blood smear imaging.

Icariin inhibits the osteoclast formation induced by RANKL and macrophage-colony stimulating factor in mouse bone marrow culture

Icariin is a prenylated flavonol glycoside contained in the herb Epimedium, which has long been used to improve bone fracture healing or prevent osteoporosis because of the belief that the herb has bone-strengthening action. We have previously demonstrated that icariin enhances the osteogenic differentiation of rat bone marrow stromal cells, and partially explained the bone-strengthening mechanism of the herb. In the present study, the effect of icariin on osteoclastogenesis and bone resorption activity was investigated in mouse bone marrow culture. It was found that icariin dose-dependently inhibited the growth and differentiation of hemopoietic cells from which osteoclasts were formed. Far less TRAP+ multinuclear cells appeared in the 10 microM icariin group than in the control. The bone resorption pits formed in the 10 microM icariin group was also significantly less than that of the control. RT-PCR analysis showed that the gene expression of TRAP, RANK and CTR was obviously lower than that of the control. It can be concluded that icariin has the ability to inhibit the formation and bone resorption activity of osteoclasts, which suggests that icariin should be the effective component for the bone-strengthening action of herb Epimedium.

Potent antitumor efficacy of XAF1 delivered by conditionally replicative adenovirus vector via caspase-independent apoptosis

XAF1 is a newly identified tumor-suppressor gene that can antagonize XIAP and sensitize cells to other cell death triggers. In this study, we utilized ZD55, a conditionally replicative adenovirus (CRAd) similar to ONYX-015 as the vector to transfer XAF1 into the tumor cells to evaluate its antitumor efficacy in vitro and in vivo. Potent and specific cytopathic effect (CPE) was observed upon infection with ZD55-XAF1 in tumor cell lines. Importantly, ZD55-XAF1 exhibited a superior suppression of tumor growth in an animal model of colorectal carcinoma in nude mice compared with Ad-XAF1 (E1-deleted replication-defective viral) and ONYX-015. Complete eradication of the established tumors was observed in four of eight mice. Our data also showed that infection with ZD55-XAF1 resulted in caspase-independent apoptosis. Although caspase-3, poly(ADP-ribose) polymerase were mildly activated in response to ZD55-XAF1 infection, pretreatment with pan-caspase inhibitor hardly influence its apoptosis-inducing activity. In summary, our study strongly suggested that ZD55-XAF1 could serve as an effective gene-virotherapy strategy and has highly potential against human cancers.

Pathogenic effects of the coccidium Eimeria ninakohlyakimovae in goats

Twenty-four coccidia-free goats were reared artificially in indoor cages and allocated to 6 groups of 4 animals each. At 20 days of age, goats in groups 1-3 received 10(4),10(5) and 10(6) sporulated oocysts of Eimeria ninakohlyakimovae per goat, respectively, each as a single dose. Goats in group 4 received daily doses increasing over a 3-week period, starting with 100/day for the first week, followed by 1000, and 10,000/day in weeks 2, 3, respectively. Goats in group 5 received 10(4) oocysts following a challenge dose of 10(6) oocysts on day 32. Goats in group 6 were kept as uninoculated controls. Infected animals showed diarrhoea and weight loss. Goats in group 4 showed longer periods of diarrhoea and patency than other infected goats. Goats in group 5 showed the same severe clinical signs as those in group 3 but produced very low oocyst output after a challenge dose. The diarrhoea was associated with a reduction in alkaline phosphatase activity and increases in packed cell volume and haemoglobin. No significant differences were found in serum aspartate aminotransferase, alanine aminotransferase, total protein, albumin, globulin, Na+, K+,Cl- between groups during 48 days after inoculation. There were no serum enzyme indications of damage to the liver. Histological examination performed 100 days after inoculation revealed that inoculated goats had mild subacute to chronic proliferative enteritis in the lower small intestine and the large intestine, and the mesenteric lymph nodes, gallbladders and livers also showed slight histological lesions. The results showed that E. ninakohlyakimovae was highly pathogenic.

Evaluation of cytotoxic activities of some medicinal polypore fungi from China

The petrol ether, ethyl acetate and methanol extracts of eight medicinal polypore fungi from China were evaluated for cytotoxic activities using MTT-dye assay. All the petrol ether and ethyl acetate extracts exhibited cytotoxicity against human cervix epitheloid carcinoma cell lines (Hela) and human hepatoma cell lines (SMMC-7721). Cytotoxicity activity was also observed in the methanol extracts of Phellinus conchatus and Pycnoporus sanquineus, but the methanol extracts from Cryptoporus volvatus, Fomitopsis pinicola, Fomes hornodermus, Lenzites betulina, Trametes gibbosa and Trametes orientalis showed weak activity when compared with quercetin.

Traditional Chinese medicine Bao Gan Ning increase phosphorylation of CREB in liver fibrosis in vivo and in vitro

Previous studies have demonstrated that traditional Chinese medicine Bao Gan Ning, which contains six different drugs: Trionyx sinensis Wiegmann shell, Prunus persica (L.) Batsch seed, Salvia miltiorrhiza Bge. root, Mallotus opelta (Lour.) Muell-Arg root, Astragalus membranaceus (Fisch.) Bge. var. mongho-licus (Bge.) Hsiao root and Scutellaria baicalensis Georgi root, was able to protect liver against fibrosis in CCL4 models. In an effort to elucidate molecular mechanisms by which Bao Gan Ning exerts its anti-fibrosis activity, effects of Bao Gan Ning on liver fibrosis and cAMP response element binding protein (CREB), an important transcription factor involved in liver fibrosis, were evaluated in animal and cell models in this work. Results showed that Bao Gan Ning (2.16 or 4.32 g/kg/day) significantly decreased alanine aminotransferase (ALT) and hyaluronidase levels and reversed liver fibrosis in rat liver fibrosis models. The proliferation of HSC-T6, a hepatic stellate cell line, was also significantly inhibited by incubation with serums that were prepared from rats fed with Bao Gan Ning. Most interestingly, results from Western blot, immunohistochemistry and electrophoretic mobility shift assay (EMSA) showed that Bao Gan Ning up-regulated CREB phosphorylation both in rat liver fibrosis models and in HSC-T6 cells, but did not affect protein level of CREB and the DNA binding activity of CREB. These results suggested that up-regulation of CREB phosphorylation may be involved in anti-fibrosis activity of Chinese medicine Bao Gan Ning.

Mesoscopic resistance fluctuations in cobalt nanoparticles

We present measurements of mesoscopic resistance fluctuations in cobalt nanoparticles and study how the fluctuations with bias voltage, bias fingerprints, respond to magnetization-reversal processes. Bias fingerprints rearrange when domains are nucleated or annihilated. The domain wall causes an electron wave function-phase shift of approximately equal to 5pi. The phase shift is not caused by the Aharonov-Bohm effect; we explain how it arises from the mistracking effect, where electron spins lag in orientation with respect to the moments inside the domain wall. Dephasing time in Co at 0.03 K is short, tau phi approximately 1 ps, which we attribute to the strong magnetocrystalline anisotropy.

Icariin, a flavonoid from the herb Epimedium enhances the osteogenic differentiation of rat primary bone marrow stromal cells

The herb Epimedium has long been used in Traditional Chinese Medicine to treat bone fracture and prevent osteoporosis. Researchers believe that the flavonoids contained in the herb are the effective component for this activity. However, no single flavonoid has been studied for its effect on bone-related cells. In the present study, icariin, one of the major flavonoids of the herb, supplemented the primary culture medium of rat bone marrow stromal cells (rMSCs) at 0.1 microM , 1 microM and 10 microM respectively. It was found that icariin stimulated the proliferation of rMSCs and increased the number of CFU-F stained positive for alkaline phosphatase in a dose-dependent manner. Icariin also dose-dependently increased the alkaline phosphatase activity, osteoalcin secretion and calcium deposition level of rMSCs during osteogenic induction. The addition of 10 microM icariin caused four times more mineralized bone nodules to be formed by rMSCs than in the control. The results demonstrated that icariin should be an effective component for bone-strengthening activity, and one of the mechanisms is to stimulate the proliferation and enhance the osteogenic differentiation of MSCs.

Bioactivity of titanium following sodium plasma immersion ion implantation and deposition

Bio-activation of titanium surface by Na plasma immersion ion implantation and deposition (PIII and D) is illustrated by precipitation of calcium phosphate and cell culture. The bioactivity of the plasma-implanted titanium is compared to that of the untreated, Na beam-line implanted and NaOH-treated titanium samples. Our data show that the samples can be classified into two groups: non-bioactive (untreated titanium and beam-line Na implanted titanium) and bioactive (Na-PIII and D and NaOH-treated titanium). None of the four types of surfaces exhibited major cell toxicity as determined by lactate dehydrogenase (LDH) release. However, the LDH release was higher on the more bioactive PIII and NaOH-treated surfaces. From a morphological point of view, cell adherence on the NaOH-treated titanium is the best. On the other hand, the cell activity and protein production were higher on the non-bioactive surfaces. The high alkaline phosphatase activity per cell suggests that the active surfaces support an osteogenic differentiation of the bone marrow cells at the expense of lower proliferation. The use of Na-PIII and D provides an environmentally cleaner technology to improve the bioactivity of Ti compared to conventional wet chemical processes. The technique is also particularly useful for the uniform and conforming treatment of medical implants that typically possess an irregular shape and are difficult to treat by conventional ion beam techniques.

SMGA gels for the skin permeation of haloperidol

Small molecule gelling agent (SMGA) gels were developed using the gelator GP-1 in the solvents, namely, isostearyl alcohol (ISA) and propylene glycol (PG), to deliver haloperidol through the skin. The concentrations of the drug, haloperidol, the enhancer, farnesol and the gelator, GP-1 are 3 mg/ml, 5% (w/v) and 5% (w/v), respectively. The study employed a three-factor full factorial statistical design to investigate the influence of factor level changes on the permeability coefficient and permeation lag-time of haloperidol. Gels were prepared by raising temperature to 120 degrees C, followed by natural cooling under room temperature of 22+/-1 degrees C. The rheological properties of the gels were examined with a strain-controlled dynamic mechanical method. The in vitro permeation study was conducted with automated flow-through type cells. The gels successfully incorporated the drug and enhancer without losing their aesthetic properties. The in vitro human skin permeation study showed the permeation of the drug in ISA-based gels reached the pseudo steady state faster than PG-based gels and were less affected by gelator. PG-based gels delivered the drug at a faster rate with the incorporation of the enhancer. GP-1 did not influence the drug permeation rate but it increased permeation lag-time. The co-existence of gelator or enhancer increased the lag-time to a larger extent than when used separately. The novel SMGA gels are suitable for topical or transdermal delivery.

Carbon plasma immersion ion implantation of nickel–titanium shape memory alloys

Nickel-titanium (NiTi) shape memory alloys possess super-elasticity in addition to the well-known shape memory effect and are potentially suitable for orthopedic implants. However, a critical concern is the release of harmful Ni ions from the implants into the living tissues. We propose to enhance the corrosion resistance and other surface and biological properties of NiTi using carbon plasma immersion ion implantation and deposition (PIII&D). Our corrosion and simulated body fluid tests indicate that either an ion-mixed amorphous carbon coating fabricated by PIII&D or direct carbon PIII can drastically improve the corrosion resistance and block the out-diffusion of Ni from the materials. Our tribological tests show that the treated surfaces are mechanically more superior and cytotoxicity tests reveal that both sets of plasma-treated samples favor adhesion and proliferation of osteoblasts.

Molecular dynamics simulation of paracetamol molecules ordering around glycogen

By the use of classical atomistic molecular dynamics simulations, we demonstrate that paracetamol molecules exist in a highly ordered phase in the presence of a glycogen substrate at 317 K whereas the paracetamol fluid exists in an isotropic phase in the absence of the glycogen substrate at the same temperature. This result further validates the studies made on polysaccharide regarding its abilities to promote nucleation of paracetamol via liquid preordering. As little is known regarding liquid ordering induced by a polymeric substrate, we seek to explore the ordering mechanism from an energy perspective. This is accomplished using conformation mappings. Our analysis shows that the conformation space accessible to the paracetamol molecule at 317 K in the vicinity of glycogen is smaller than the one in the absence of glycogen. An investigation on the orientation of the dipole moments of the glycogen monomers and paracetamol molecules were carried out as well. From the investigations, we show that dipolar interactions play an important role in the ordering process. These studies bear significance to the understanding of the ordering process as well as the promotion and effective control of the nucleation rate.

Investigation of nickel suppression and cytocompatibility of surface-treated nickel-titanium shape memory alloys by using plasma immersion ion implantation

Nickel-titanium (NiTi) shape memory alloys are increasingly being used in orthopedic applications. However, there is a concern that Ni is harmful to the human body. We have recently investigated the use of nitrogen, or oxygen plasma immersion ion implantation to mitigate this deleterious effect. Our results reveal that the near-surface Ni concentration in all the treated samples is significantly suppressed. In addition, our in vitro tests show that the plasma-treated surfaces are cytologically compatible allowing the attachment and proliferation of osteoblasts. Among the two types of samples, the best biological effects are found on the samples with nitrogen implantation.

Investigation of nickel suppression and cytocompatibility of surface-treated nickel-titanium shape memory alloys by using plasma immersion ion implantation

Nickel-titanium (NiTi) shape memory alloys are increasingly being used in orthopedic applications. However, there is a concern that Ni is harmful to the human body. We have recently investigated the use of nitrogen, or oxygen plasma immersion ion implantation to mitigate this deleterious effect. Our results reveal that the near-surface Ni concentration in all the treated samples is significantly suppressed. In addition, our in vitro tests show that the plasma-treated surfaces are cytologically compatible allowing the attachment and proliferation of osteoblasts. Among the two types of samples, the best biological effects are found on the samples with nitrogen implantation.

Corrosion resistance, surface mechanical properties, and cytocompatibility of plasma immersion ion implantation-treated nickel-titanium shape memory alloys

Nickel-titanium shape memory alloys are promising materials in orthopedic applications because of their unique properties. However, for prolonged use in a human body, deterioration of the corrosion resistance of the materials becomes a critical issue because of the increasing possibility of deleterious ions released from the substrate to living tissues. We have investigated the use of nitrogen, acetylene, and oxygen plasma immersion ion implantation (PIII) to improve the corrosion resistance and mechanical properties of the materials. Our results reveal that the corrosion resistance and mechanical properties such as hardness and elastic modulus are significantly enhanced after surface treatment. The release of nickel is drastically reduced as compared with the untreated control. In addition, our in vitro tests show that the plasma-treated surfaces are well tolerated by osteoblasts. Among the three types of samples, the best biological effects are observed on the nitrogen PIII samples.