Single nanowire manipulation within dielectrophoretic force fields in the sub-crossover frequency regime

This paper presents the quantitative relationship between the control parameters of a dielectrophoretic (DEP) force field and the resulting electrokinetic region of influence experienced by individual nanowires (NWs) in colloidal suspensions. Our results show that DEP operation at sub-crossover frequencies, which are defined as frequencies slightly below the transition from positive-to-negative DEP, offers a suitable but previously unexplored performance regime for single NW manipulation and assembly. The low-magnitude DEP forces at these frequencies, which are estimated to be 8 orders of magnitude smaller as compared to near-DC frequencies, provide an efficient avenue to controllably extend electrokinetic influence on suspension volumes that present isolated NWs. These results are demonstrated using α-phase manganese dioxide NWs as a model one-dimensional construct. Based on experimentally extracted values for the NW intrinsic conductivity and dielectric permittivity, we employ computational models to explain each of the performance regimes observed in this nanoassembly system. In addition, we use a new approach to estimate the concentration of a NW suspension from experimentally observed data for deposition yields.

Elastic Modulus Measurements on Large Diameter Nanowires Using a Nano-Assembled Platform

This paper presents atomic force spectroscopy (AFM) results from large diameter nanowires (NWs), which range in radius from 150 nm to 300 nm, within a nano-assembled platform. The nanomechanical platform is constructed by assembling single NWs across pairs of gold nano-electrodes using dielectrophoresis and contains a short, suspended segment of the NW (in air) between the assembly electrodes. Atomic force microscope (AFM) force spectroscopy measurements are obtained by indenting the NW within this suspended segment and result in deformation of the NW involving a combination of both, bending and nano-indentation modes. This paper demonstrates the measurement technique using lithium iron phosphate NWs as a model system and presents a finite element model to extract the Young's modulus from nanomechanical data. The estimated Young's modulus of this material, which is an electrode material system of interest for next-generation lithium-ion batteries, was found to be diameter dependent and was observed to range in values between 100 MPa and 575 MPa.

On-chip lithium cells for electrical and structural characterization of single nanowire electrodes

We present a transmission electron microscopy (TEM)-compatible, hybrid nanomachined, on-chip construct for probing the structural and electrical changes in individual nanowire electrodes during lithium insertion. We have assembled arrays of individual β-phase manganese dioxide (β-MnO2) nanowires (NWs), which are employed as a model material system, into functional electrochemical cells through a combination of bottom-up (dielectrophoresis) and top-down (silicon nanomachining) unit processes. The on-chip NWs are electrochemically lithiated inside a helium-filled glovebox and their electrical conductivity is studied as a function of incremental lithium loading during initial lithiation. We observe a dramatic reduction in NW conductivity (on the order of two to three orders in magnitude), which is not reversed when the lithium is extracted from the nanoelectrode. This conductivity change is attributed to an increase in lattice disorder within the material, which is observed from TEM images of the lithiated NWs. Furthermore, electron energy loss spectroscopy (EELS) was employed to confirm the reduction in valence state of manganese, which occurs due to the transformation of MnO2 to LixMnO2.

Epidemiology, risk factors, and outcomes of Clostridium difficile infection in kidney transplant recipients

BACKGROUND

We sought to describe the epidemiology and risk factors for Clostridium difficile infection (CDI) among kidney transplant recipients (KTR) between 1 January 2008 and 31 December 2010.

METHODS

A single-institution retrospective study was conducted among all adult KTR with CDI, defined as a positive test for C. difficile by a cell cytotoxic assay for C. difficile toxin A or B or polymerase chain reaction test for toxigenic C. difficile.

RESULTS

Among 603 kidney transplants performed between 1 January 2008 and 31 December 2010, 37 (6.1%) patients developed CDI: 12 (of 128; 9.4%) high-risk (blood group incompatible and/or anti-human leukocyte antigen donor-specific antibodies) vs. 25 (of 475; 5.3%, P = 0.08) standard-risk patients. The overall rate of CDI increased from 3.7% in 2008 to 9.4% in 2010 (P = 0.05). The median time to CDI diagnosis was 9 days, with 27 (73.0%) patients developing CDI within the first 30 days after their transplant, and 14 (51.8%) developing CDI within 7 days. A case-control analysis of 37 CDI cases and 74 matched controls demonstrated the following predictors for CDI among KTR: vancomycin-resistant Enterococcus colonization before transplant (odds ratio [OR]: 3.6, P = 0.03), receipt of an organ from Centers for Disease Control high-risk donor (OR: 5.9, P = 0.006), and administration of high-risk antibiotics within 30 days post transplant (OR: 6.6, P = 0.001).

CONCLUSIONS

CDI remains a common early complication in KTR, with rates steadily increasing during the study period. Host and transplant-related factors and exposure to antibiotics appeared to significantly impact the risk for CDI among KTR.

Follicular and endocrinological turnover associated with GnRH induced follicular wave synchronization in Indian crossbred cows

The goal of this study was to record the hormonal and follicular turnover in Jersey crossbred cows when subjected for follicular wave synchronization using GnRH. Six healthy, non-lactating and regularly cycling Jersey crossbred cows (5-6 y) were used for the study. In the control group, the follicular wave pattern was ultrasonographically investigated in 18 cycles (3 cycles/cow). In the treatment group, GnRH analogue (buserelin acetate 10 μg im) was administered on Day 6 of the cycle and follicular wave pattern was studied in 12 cycles (2 cycles/animal). Follicular population was categorized based on their diameter Class I, ≤5 mm; Class II, >5-<9 mm; Class III, ≥9 mm) and the number of follicles in each category was determined on Day 6, Day 8 and Day 10. Plasma FSH and progesterone concentrations were estimated in both control and treatment groups. Out of 18 estrous cycles studied, 14 cycles (77.8%), three cycles (16.7%) and one cycle (5.6%) exhibited three-, two- and four-follicular waves per cycle, respectively. It was evident that the DF of Wave I established its dominance and was in the growing phase by Day 6 of the estrous cycle in all the normally cycling crossbred cows. The DF ovulated in all the animals (100%) in the mean interval of 27.7 ± 0.2 h after GnRH administration. A synchronized homogenous group of follicles emerged two days after GnRH injection (Day of 8.0 ± 0.0) in all the animals (100%). The combination of LH surge induced ovulation of DF (abrupt termination of Wave I) and FSH surge stimulated homogenous recruitment of Class I follicles, led to a synchronized emergence of follicular wave. All the GnRH treated cows had three follicular waves because of early emergence and short period of dominance of Wave II DF.

Temporary vascular shunts

Temporary vascular shunts have been used for nearly 100 years in patients. Originally, they were used as vascular grafts that were likely to thrombose as collaterals would hopefully develop. More recently, they have been used as a device to be replaced by a permanent vascular graft during the same operation or at a reoperation. Indications for the use of shunts are a "damage control" procedure for a peripheral or truncal vascular injury, Gustilo IIIC fracture of an extremity, need for perfusion as a complex revascularization is performed, and planned replantation of a hand, forearm, or arm. They are used in approximately 8% of vascular injuries treated in urban trauma centers in the United States and have an excellent patency rate without heparinization.

Donor-derived organ transplant transmission of coccidioidomycosis

Coccidioidomycosis in solid organ transplant recipients most often occurs as a result of primary infection or reactivation of latent infection. Herein, we report a series of cases of transplant-related transmission of coccidioidomycosis from a single donor from a non-endemic region whose organs were transplanted to 5 different recipients. In all, 3 of the 5 recipients developed evidence of Coccidioides infection, 2 of whom had disseminated disease. The degree of T-cell immunosuppression and timing of antifungal therapy initiation likely contributed to development of disease and disease severity in these recipients. This case series highlights the importance of having a high index of suspicion for Coccidioides infection in solid organ transplant recipients, even if the donor does not have known exposure, given the difficulties of obtaining a detailed and accurate travel history from next-of-kin.

Outcome analysis of trapezectomy with and without pyrocarbon interposition to treat primary arthrosis of the trapeziometacarpal joint

We performed a prospective cohort comparative analysis of simple trapezectomy and trapezectomy with pyrocarbon interposition in 38 consecutive patients with trapeziometacarpal joint osteoarthrosis. Patients were assessed preoperatively, at six and 12 months postoperatively using subjective and objective tools. Subjective assessment was performed using the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire and the visual analogue score. Objective assessment was performed with grip strength measurements. At each time interval, statistical differences were sought between the two subgroups. No significant difference between the two subgroups was noted at any time interval on subjective or objective assessment. A significant difference (p < 0.05) was found on comparing the respective preoperative and 12-month subjective scores in both subgroups. Of the pyrocarbon subgroup seven had related complications. We suggest that pyrocarbon interposition does not significantly improve postoperative function, requires a longer operation with a high postoperative risk of pyrocarbon displacement and need for revision surgery.

Sequential co-immobilization of thrombomodulin and endothelial protein C receptor on polyurethane: activation of protein C

In an effort to control the surface-mediated activation of thrombin and clot formation, proteins and molecules which mimic the anticoagulant properties of the vascular endothelial lining were immobilized on material surfaces. When immobilized on biomaterial surfaces, thrombomodulin (TM), an endothelial glycoprotein that binds thrombin and activates protein C (PC), was shown to generate activated PC (APC) and delay clot formation. However, TM-mediated activation of PC on biomaterial surfaces was shown to be limited by the transport of PC to the surface, with maximum activation obtained at a surface density of ∼40 fmole TM cm(-2). This work investigates surface immobilized with TM and endothelial protein C receptor (EPCR), a natural cofactor to TM which increases the rate of activation of PC on the native endothelium. A sequential and ordered immobilization of TM and EPCR on polyurethane at an enzymatically relevant distance (<10 nm) resulted in higher amounts of APC compared with surfaces with immobilized TM or with TM and EPCR immobilized randomly and at TM surface densities (1400 fmole cm(-2)) which were previously shown to be transport limited. Ordered TM and EPCR samples also showed increased time to clot formation in experiments with platelet-poor plasma, as measured by thromboelastography. Surfaces immobilized with TM and its natural cofactor EPCR at an enzymatically relevant distance are able to overcome transport limitations, increasing anticoagulant activation and time to clot formation.

In Situ Observation of the Electrochemical Lithiation of a Single SnO2 Nanowire Electrode

We report the creation of a nanoscale electrochemical device inside a transmission electron microscope—consisting of a single tin dioxide (SnO2) nanowire anode, an ionic liquid electrolyte, and a bulk lithium cobalt dioxide (LiCoO2) cathode—and the in situ observation of the lithiation of the SnO2 nanowire during electrochemical charging. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. The reaction front is a “Medusa zone” containing a high density of mobile dislocations, which are continuously nucleated and absorbed at the moving front. This dislocation cloud indicates large in-plane misfit stresses and is a structural precursor to electrochemically driven solid-state amorphization. Because lithiation-induced volume expansion, plasticity, and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high-capacity anodes in lithium-ion batteries, our observations provide important mechanistic insight for the design of advanced batteries.

Cardiac arrest caused by undersensing of a temporary epicardial pacemaker

The R-on-T phenomenon is a well-known entity that predisposes to dangerous arrhythmias. Typically, a premature ventricular complex occurring at the critical time during the T wave of the preceding beat precipitates ventricular tachycardia and fibrillation. This phenomenon can occur not only in asynchronous ventricular pacemakers, but also in synchronous pacemakers, if loss of sensing of the intrinsic rhythm becomes evident. A patient who was fitted with a temporary epicardial wire, following cardiac surgery and experienced repeated episodes of polymorphic ventricular tachycardia caused by the R-on-T phenomenon, is described.

Necrotising soft tissue infection following mastectomy

Necrotising fasciitis is a rare but rapidly progressive soft tissue disease which can lead to extensive necrosis, systemic sepsis and death. Including this case, only 7 other cases have been reported in the world literature with only 2 others affecting the patient post mastectomy. This 59 year old Caucasian lady presented with severe soft tissue infection soon after mastectomy, which was successfully treated with a combination of debridement, triangulation, VAC© dressing and skin grafting. Necrotising soft tissue infections following mastectomy are rapidly progressive and potentially extremely serious. It is essential that a high index of clinical suspicion is maintained together with prompt aggressive treatment in a multidisciplinary environment to prevent worsening physical and psychological sequelae.

Polyoxazoline-peptide adducts that retain antibody avidity

Synthetic polymers have long been used to modify various properties of proteins such as activity and solubility. Polyethylene glycol (PEG) has been widely used to form adducts with enzymes and antibodies. In this study, the polyoxazoline family of water-soluble polymers was used to synthesize adducts containing a synthetic peptide recognized by a monoclonal antibody (MAb) directed against human protein C (hPC). This is the first application of direct conjugation of unterminated or "living" polymer to a peptide. The avidity of the antibody for the various adducts was characterized with respect to size and hydrophilicity of methyl- and ethyl-substituted polyoxazoline polymers (POX). Avidity of the adducts was not found to be dependent upon the hydrophilicity and was slightly decreased due to polymer modification. The methyl-POX-peptide adducts were found to be highly water soluble, while the ethyl-POX-peptide adducts showed sporadic problems with aqueous solubility. Because the polymer-peptide adducts retained avidity for the antibody, polyoxazoline polymers may have potential application to protein-adduct chemistry.

Stability and analysis of configuration-tunable bi-directional MWNT bearings

We report on the energetic and structural stability of configuration-tunable, bi-directional linear bearings based on cap-less, partial segments engineered within individual multi-walled carbon nanotubes (MWNTs). Using computational models, we show that an externally applied excitation force can be used to select an operating bearing configuration with a desired stiffness and operating frequency. Our models also demonstrate the possibility of simultaneous, independent operation of multiple bearings within a single NT segment, paving the way towards ultra-high device densities with molecular-scale footprints.

Electrostatic actuation and electromechanical switching behavior of one-dimensional nanostructures

We report on the electromechanical actuation and switching performance of nanoconstructs involving doubly clamped, individual multiwalled carbon nanotubes. Batch-fabricated, three-state switches with low ON-state voltages (6.7 V average) are demonstrated. A nanoassembly architecture that permits individual probing of one device at a time without crosstalk from other nanotubes, which are originally assembled in parallel, is presented. Experimental investigations into device performance metrics such as hysteresis, repeatability and failure modes are presented. Furthermore, current-driven shell etching is demonstrated as a tool to tune the nanomechanical clamping configuration, stiffness, and actuation voltage of fabricated devices. Computational models, which take into account the nonlinearities induced by stress-stiffening of 1-D nanowires at large deformations, are presented. Apart from providing accurate estimates of device performance, these models provide new insights into the extension of stable travel range in electrostatically actuated nanowire-based constructs as compared to their microscale counterparts.

Rapid prediction of composition and flavor quality of cheddar cheese using ATR-FTIR spectroscopy

Multiple methods are required for analysis of cheese flavor quality and composition. Chromatography and sensory analyses are accurate but laborious, expensive, and time consuming. A rapid and simple instrumental method based on Fourier transform infrared (FTIR) spectroscopy was developed for simultaneous analysis of Cheddar cheese composition and flavor quality. Twelve different Cheddar cheese samples ripened for 67 d were obtained from a commercial cheese manufacturer along with their moisture, pH, salt, fat content, and sensory flavor quality data. Water-soluble components were extracted from the cheese, dried on zinc selenide FTIR crystal and scanned (4000 to 700 cm(-1)). Infrared spectra of the samples were correlated with their composition and flavor quality data to develop multivariate statistical regression and classification models. The models were validated using an independent set of ten 67-d-old test samples. The infrared spectra of the samples were well defined, highly consistent within each sample and distinct from other samples. The regression models showed excellent fit (r > 0.92) and could accurately determine moisture, pH, salt, and fat contents as well as the flavor quality rating in less than 20 min. Furthermore, cheeses could also be classified based on their flavor quality (slight acid, whey taint, good cheddar, and so on). The discrimination of the samples was due to organic acids, amino acids, and short chain fatty acids (1800 to 900 cm(-1)), which are known to contribute significantly to cheese flavor. The results show that this technique can be a rapid, inexpensive, and simple tool for predicting composition and flavor quality of cheese.

The BSG/ACPGBI guidelines for colonoscopic screening: what are we missing?

INTRODUCTION

Before publication of the British Society of Gastroenterology and Association of Coloproctology of Great Britain and Ireland guidelines in 2002, screening for people with a family history of colorectal cancer was sporadic and largely dependant on unvalidated local guidelines. Since 1990 we have been screening patients with both high and moderate risk family histories of colorectal cancer using local protocols which were more liberal than the new guidelines. In this study, we have analysed the pathology that would have been missed if we had been using the new guidelines in the period 1990-2002.

METHOD

A total of 399 consecutive patients with a positive family history of colorectal malignancy underwent screening endoscopy according to local guidelines. Demographic, endoscopic and pathologic data were prospectively collected. Patients were retrospectively divided into those who would have been screened under the new guidelines (group 1) and those who would not (group 2). The recorded pathology was graded as significant or insignificant and the findings compared between the two groups.

RESULTS

A total of 399 patients underwent 557 endoscopies of which 278 (50%) were indicated under the new guidelines (group 1) and 279 (50%) were not indicated (group 2). A significant pathology or carcinoma was found in 15.8% of group 1 endoscopies and 10.0% of group 2 endoscopies. This difference was significant.

CONCLUSION

If we had been using the new guidelines in the period 1990-2002, we would not have performed 279 (50%) of the 557 procedures, but would not have discovered significant pathology in 10% of the moderate risk endoscopies representing 39% of the significant pathology, which was actually present in this population.

A fundamental study of the PCR amplification of GC-rich DNA templates

A theoretical analysis is presented with experimental confirmation to conclusively demonstrate the critical role that annealing plays in efficient PCR amplification of GC-rich templates. The analysis is focused on the annealing of primers at alternative binding sites (competitive annealing) and the main result is a quantitative expression of the efficiency (eta) of annealing as a function of temperature (T(A)), annealing period (t(A)), and template composition. The optimal efficiency lies in a narrow region of T(A) and t(A) for GC-rich templates and a much broader region for normal GC templates. To confirm the theoretical findings, the following genes have been PCR amplified from human cDNA template: ARX and HBB (with 78.72% and 52.99% GC, respectively). Theoretical results are in excellent agreement with the experimental findings. Optimum annealing times for GC-rich genes lie in the range of 3-6s and depend on annealing temperature. Annealing times greater than 10s yield smeared PCR amplified products. The non-GC-rich gene did not exhibit this sensitivity to annealing times. Theory and experimental results show that shorter annealing times are not only sufficient but can actually aid in more efficient PCR amplification of GC-rich templates.

Structure and local-equilibrium thermodynamics of the c(2x2) reconstruction of rutile TiO2 (100)

We resolve the structure of a c(2x2) reconstruction of the rutile TiO2 (100) surface using a combination of transmission electron diffraction, direct methods analysis, and density functional theory. The surface structure contains an ordered array of subsurface oxygen vacancies and is in local thermodynamic equilibrium with bulk TiO2, but not the with oxygen gas-phase environment. The transition into a bulklike (1x1) reconstruction offers insights into the time-dependent local thermodynamics of TiO2 surface reconstruction under global nonequilibrium conditions.

Evidence for a tumour suppressive function of IGF1-binding proteins in human breast cancer

The role of the insulin like growth factor (IGF) system in various human malignancies has been well established. The aim of this study was to determine the levels of mRNA expression of insulin-like growth factor-binding protein (IGFBP)-1, -3 and -7 genes in benign and malignant breast tissue and explore their relationship with various prognostic parameters.

MATERIALS AND METHODS

Breast cancer tissue (n=127) and normal background tissue (n-33) were prospectively collected and analysed for levels of IGFBP-1, -3 and -7 mRNA using real-time Q-PCR. mRNA levels were then analysed against tumour grade, nodal status, Nottingham prognostic index (NPI)/TNM stage and tumour type.

RESULTS

For IGFBP-1 and -3, mRNA expression was higher in normal tissue. This was significant for IGFBP-1 when comparing NPI 3 with NPI 1 (p=0.050) and the normal group (p=0.040). With respect to TNM analysis, there was less IGFBP-1 mRNA when comparing TNM 3 with normal (p=0.017), TNM 1 (p=0.047) and TNM 2 (p=0.019) tumours. This was also found when comparing TNM 4 samples with normal tissue (p=0.017), TNM 1 (p=0.046) and TNM 2 (p=0.019). For IGFBP-3 mRNA, there was less mRNA when comparing TNM 3 with TNM 1 (p= 0.017) and TNM 2 (p=0.050), and also less mRNA expression when comparing TNM 4 with TNM 1 (p=0.030). For IGFBP-7 mRNA, both TNM 1 (p=0.0077) and TNM 2 (p=0.015) had significantly more expression than TNM 3 samples.

CONCLUSION

This study supports the role of IGFBP-1, -3 and -7 as potential tumour suppressor genes in human breast cancer.

HTERT mRNA expression correlates with matrix metalloproteinase-1 and vascular endothelial growth factor expression in human breast cancer: a correlative study using RT-PCR

BACKGROUND

Telomerase activity has been significantly associated with nodal metastasis and cellular proliferation in human breast cancer, indicating that its degree of expression has some form of vital control over the invasive nature of the malignancy concerned. Of the telomerase subunits, the reverse transcriptase (hTERT) is the main determinant of enzyme activity. Vascular endothelial growth factors (VEGF)-C and (VEGF)-D, matrix metalloprotease type 1 (MMP-1) and protease-activated receptors (PARs) have all been linked to promotion of tumour invasiveness and metastatic dissemination. This study aims to examine the association between hTERT transcription and that of VEGF-D, VEGF-C, MMP-1, PAR1a and PAR1b through a correlative analysis of the mRNA transcripts of these genes in human breast cancer.

MATERIALS AND METHODS

Breast cancer tissues (n = 116) and normal tissues (n-31) were collected immediately after surgery and stored at -80 degrees C until use. The level of hTERT transcripts from the prepared DNA from the above samples was determined using real time-quantitative PCR based on the Amplifluor technology. The levels of the transcript were generated from a standard that was simultaneously amplified with the samples. Normalisation against cytokeratin 19 (CK19) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also carried out.

RESULTS

There was a positive correlation between hTERT mRNA expression (after CK19 normalisation) with both VEGF-D and MMP-1 in human breast cancer. PAR1 was seen to correlate with hTERT (after GAPDH normalisation) with a highly significant correlation with PAR1a alone. However there was no correlation between hTERT transcription and VEGF-C or with PAR1b alone.

CONCLUSION

Our findings suggest that hTERT is a potential up-regulator of MMP-1, PAR1 and VEGF-D expression and this may explain its apparent control over the invasiveness and metastasis of the malignancy concerned.

Superficial Venous Pathology in the Asian Population of South West London – A Prospective Study

OBJECTIVES

The Asian population of our hospital catchment area represents 6.2% of the total, which is 3.2% higher than the national average, compared to the Caucasian population which comprises 70.2% and is 21.9% lower than the national average. This study aimed to analyse the prevalence and presentation of superficial venous disease (SVD) in the Asian population of South West London.

METHODS

A prospectively gathered database of all 481 patients referred by local general practitioners (GP) to the varicose veins nurse specialist over a 24 month period was analyzed. Information was collected on demographics, presenting features, clinical signs, and whether surgical referral was made.

RESULTS

Asians presented significantly younger than Caucasians (p<0.0001; unpaired t-test). Caucasians had a significantly higher positive family history than Asians (p<or=0.05; chi-squared test). SVD severity was graded using the CEAP (clinical, etiological, anatomical, pathophysiological) classification. Asians had significantly more severe disease than Caucasians (p<or=0.01; chi-squared test). There were no differences in sex distribution.

CONCLUSION

Asians presented younger with more severe disease than their Caucasian counterparts. The reasons for these findings are unclear, but probably represent a combination of genetic, environmental and social factors. Further research is in progress to investigate this.

The potential clinical applications of insulin-like growth factor-1 ligand in human breast cancer

Insulin-like growth factor-1 (IGF-1) has become recognized as a growth factor with pro-mitogenic and antiapoptotic effects on a variety of human cells. This article reviews the potential role of IGF-1 ligand in the clinical management of breast cancer patients. Many studies have shown that IGF-1 acts synergistically with oestrogen to stimulate breast cancer cells. Case-control studies have also demonstrated that premenopausal women with high levels of serum IGF-1 have an increased risk of developing breast cancer later in life. Serum IGF-1 levels can therefore be used as a potential biomarker for predicting breast cancer risk. Furthermore, there is evidence that serum IGF-1 levels can serve as a response biomarker in chemoprevention drug trials. The role of IGF-1 expression in breast cancer tissue as a prognostic marker is not clearly established. Identifying the IGF-1 gene polymorphism can potentially be used in predicting breast cancer risk.

Batch fabrication of carbon nanotube bearings

Relative displacements between the atomically smooth, nested shells in multiwalled carbon nanotubes (MWNTs) can be used as a robust nanoscale motion enabling mechanism. Here, we report on a novel method suited for structuring large arrays of MWNTs into such nanobearings in a parallel fashion. By creating MWNT nanostructures with nearly identical electrical circuit resistance and heat transport conditions, uniform Joule heating across the array is used to simultaneously engineer the shell geometry via electric breakdown. The biasing approach used optimizes process metrics such as yield and cycle-time. We also present the parallel and piecewise shell engineering at different segments of a single nanotube to construct multiple, but independent, high density bearings. We anticipate this method for constructing electromechanical building blocks to be a fundamental unit process for manufacturing future nanoelectromechanical systems (NEMS) with sophisticated architectures and to drive several nanoscale transduction applications such as GHz-oscillators, shuttles, memories, syringes and actuators.

Human blood monitoring program in Japan: contamination and bioaccumulation of persistent organochlorines in Japanese residents

Concentrations of persistent organochlorines (OCs)-such as polychlorinated biphenyls (PCBs), 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), chlordane compounds (CHLs), hexachlorobenzene, and tris(4-chlorophenyl)methane [TCPMe]-were determined in plasma samples from residents of three sub-metropolitan locations in Japan (Miyako, Saku, and Tottori) for the purpose of studying the geographic variation and specific accumulation of OCs. Residue concentrations of PCBs and DDTs were the highest in samples collected in Saku (400 and 370 ng/g lipid wt, respectively) whereas samples from Miyako contained greater CHL residues (70 ng/g lipid wt) than those from the other two locations. This contamination pattern reflects the historic use of OCs in each area. For the first time, tris (4-chlorophenyl) methane (TCPMe) concentrations were detected in most of the plasma sample analyzed. Concentrations of TCPMe which ranged from <0.1 to 8.1 ng/g lipid wt eight, were lower than those previouly reported in other human tissue. Larger geographic differences in OC accumulation were observed for PCBs and CHLs, whereas DDTs and HCHs exhibited little variability. PCB concentrations in samples from Saku residents were higher than those from residents of countries in the circumpolar Arctic region but lower than those reported for some populations in the United States and Western European countries. Interestingly, CHL residue concentrations in human blood from Japan are among the highest values reported for the countries examined, suggesting continued increased exposure to CHLs of the Japanese population. Time-trend analysis of CHLs in human blood samples from Miyako (Okinawa prefecture) showed that CHL residues have decreased substantially during the last decade, indicating the effect of the official ban of CHLs in 1986 in Japan. Isomer-specific analysis of PCBs revealed lower proportions of higher chlorinated congeners such as hepta- and octachlorobiphenyls in women than in men, suggesting the possibility of preferential elimination of higher chlorinated biphenyls in women. The difference in sex-dependent accumulation of OC compounds in healthy and ill persons was suggested. To our knowledge, this is the first report on the specific accumulation of persistent QCs, including TCPMe, in human blood samples from Japan.

Contamination by persistent organic pollutants in dumping sites of Asian developing countries: implication of emerging pollution sources

In Asian developing countries, large amounts of municipal wastes are dumped daily in open dumping sites without proper management. This practice may cause several adverse environmental consequences and increased health risk to local communities. To elucidate contamination by persistent organic pollutants (POPs)--including dichloro-diphenyl-trichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs), chlordanes, hexachlorobenzene (HCB), and polychlorinated biphenyls (PCBs)--in such dumping sites, soil samples were collected from open dumping sites and respective control sites in Cambodia, India, and Vietnam from 1999 through 2001. Our results demonstrated that DDTs, PCBs, and HCHs were dominant contaminants in the dumping sites. However, the contamination pattern was not consistent, showing higher HCHs in India than in Cambodia and Vietnam. Interestingly, in all of the countries, extremely higher levels of POPs were observed in the dumping sites compared with those in the respective control sites, suggesting significant amplification of POP contamination in the dumping sites of Asian developing countries. Mean concentrations of DDTs and PCBs were 350 and 140 ng/g dry weight, respectively, in the dumping sites of Cambodia and 26 and 210 ng/g, respectively, in India. These residue levels were hundreds to thousands times higher than those in general soils, implying possible risk to human health of the local communities, especially to the rag pickers, including children who work in these sites to collect recyclable materials. Composition of DDT compounds suggested their recent use in populated areas, which in turn might have caused increased levels of DDTs in the open dumping sites. In addition, composition of HCH isomers revealed their different use pattern in different countries.

Changing trends in US injury profiles: revisiting non-fatal occupational injury statistics

The purpose of this paper is to review the current trends in non-fatal injury profiles of workers in the United States. It is generally accepted that occupational injury and illness rates are affected by many factors, such as the amount and quality of training, employee turnover rates, work experience, extent of mechanization and automation, job-related parameters, and worker gender. In the last decade, not only have the technologies used in the workplace changed significantly, there has been a greater awareness among employers and employees as to the importance of containing work injuries. Additionally, the extent of outsourcing for labor-intensive jobs has increased dramatically owing to cheaper labor costs in places such as China and Mexico. These changes have affected the manufacturing sector of US industry more than any other sector. How these changes have influenced the injury and illness profiles of the American worker is of considerable interest given the increased attention paid to work-workplace design, injury hazard control, and ergonomics in general. In this paper, we compare the injury and illness profiles of US workers separated by nearly a decade. The trends from early 1990s are compared to those from early 2000s. Data from the Bureau of Labor Statistics were used to compile the injury statistics. The results of our comparison show that while the absolute numbers of work-related injuries and illnesses have declined over the last 10 years, the basic trends associated with different factors remain almost unchanged. The reasons for this decline are discussed in this paper.