Broadband multi-layer terahertz metamaterials fabrication and characterization on flexible substrates

Microscopic split-ring-resonator (SRR) arrays are fabricated on 100 μm thick polyethylene naphthalate (PEN) films by femtosecond laser micro-lens array (MLA) lithography. The transmission properties of these metamaterials are characterized by THz Time Domain Spectroscopy (THz-TDS). Tunable resonance responses can be achieved by changing SRR structural design parameters. By stacking 2D PEN metamaterial films with different frequency responses together, a broadband THz filter with full width at half maximum (FWHM) of 0.38 THz is constructed. The bandwidth of the resonance response increases up to 4.2 times as compared to the bandwidths of single layer metamaterials. Numerical simulation reveals that SRR layers inside the multi-layer metamaterials are selectively excited towards specific frequencies within the broadband response. Meanwhile, more than one SRR layers respond to the chosen frequencies, resulting in the enhancement of the resonance properties. The multi-layer metamaterials provide a promising way to extend SRR based metamaterial operating region from narrowband to broadband with a tunable feature.

Influence of fouling on the efficiency of sacrificial anodes in providing cathodic protection in Southeast Asian tropical seawater

Aluminum and zinc based sacrificial anodes are routinely used to provide corrosion protection to metals (typically steel) exposed to seawater, for example in steel pipelines and storage tanks. However, the high fouling rates experienced in South East Asia means that both the anodes and the metals to be protected rapidly become coated with macrofoulers, which could potentially prevent the anodes from being effective. The present study, involving exposure tests of up to 18 months, indicates that both aluminum and zinc sacrificial anodes remain effective even after being completely coated with biofouling. Furthermore, it was easier to remove the biofouling on the cathodically protected samples than on their unprotected counterparts, possibly due to the higher local pH produced by cathodic protection at the metal and seawater interface.

Current Practice of Obtaining Informed Consent for Local Steroid Injection among the Shoulder and Elbow Surgeons in United Kingdom

Background

Local steroid injection is a common procedure and not without risks.

Aim

To establish the current practice of obtaining informed consent for local steroid injection among shoulder and elbow surgeons in the UK.

Methods

A postal questionnaire survey was distributed to 176 orthopaedics surgeons in UK who were members of the British Elbow and Shoulder Society.

Results

68% of the surgeons considered local steroid injection invasive. 88% of the surgeons obtained verbal consent only. Of these, only 19% recorded the discussion. Almost all the surgeons (96%) explained the desired effects and 26% provided statistical evidence of local steroid injection. About 88% of the surgeons mentioned other drugs included in the injection. Only 13% of them mentioned the dose of the steroid used. 82% and 77% of the surgeons offered alternative treatment options and the right to refuse injection respectively. 85% and 59% of the surgeons discussed local and systemic risks of steroid injection, respectively. The most common risk mentioned by the surgeons is short term increase of pain.

Conclusions

Majority of the surgeons used verbal consent only for local steroid injection. The consent discussion was not regularly documented in case notes and the information delivered varies.

Secondary care treatment of patients with varicose veins in National Health Service England: at least how it appeared on a National Health Service website

Objectives

This study aimed to assess the trends and regional variations in secondary care treatment of patients with varicose veins in National Health Service (NHS) England based on data published by the Hospital Episode Statistics which was freely and readily available to the public and health-care policy-makers.

Methods

Hospital Episode Statistics data for patients being treated for varicose veins, and UK Statistics Authority population estimates in all 28 Strategic Health Authorities (SHAs) in England from 2002 to 2006 were retrieved and analysed.

Results

Between 2002 and 2006 there was a 20% overall reduction (46,190–37,135) in the total number of varicose vein procedures performed in NHS England per year. The number of varicose vein procedures performed per 100,000 population per year varied significantly across the SHAs ( P < 0.0001). Similarly, significant regional variations were also noted in the frequency of primary procedures of greater and small saphenous vein ( P < 0.0001). During this time, injection sclerotherapy was only performed in 15 (53.6%) SHAs. The annual proportion of varicose vein procedures performed as daycases had increased from 56% to 64% during the period.

Conclusion

From 2002 to 2006 there was an overall reduction in the total number of varicose vein procedures performed in NHS England with major regional variations.

Hybrid metamaterial design and fabrication for terahertz resonance response enhancement

Planar hybrid metamaterial with different split ring resonators (SRR) structure dimensions are fabricated on silicon substrates by femtosecond (fs) laser micro-lens array (MLA) lithography and lift-off process. The fabricated metamaterial structures consist of: (a) uniform metamaterial with 4 SRRs at same design and dimension as a unit cell and (b) hybrid metamaterial with 4 SRRs at same design but different dimensions as a unit cell. The electromagnetic field responses of these hybrid and single dimension metamaterial structures are characterized using a terahertz (THz) time-domain spectroscopy. Transmission spectra of these metamaterial show that a broader resonance peak is formed when 2 SRRs are close to each other. FDTD simulation proves that there is a strong mutual coupling between 2 SRRs besides a strong localized electric field at the split gap, which can enhance the electric field up to 364 times for tunable, broad band and high sensitivity THz sensing. Meanwhile, the strong coupling effect could lead to the formation of an additional resonance peak at approximately 0.2 THz in the THz spectra regime.

An optofluidic volume refractometer using Fabry-Pérot resonator with tunable liquid microlenses

This letter reports the development of an optofluidic Fabry-Pérot (FP) resonator, which consists of a microcavity and a pair of liquid microlenses. The microcavity forms part of the microchannel to facilitate sample injection. The liquid microlenses are used for efficient light coupling from the optical fiber to the microcavity. The liquid microlens collimates the diverging light from the optical fiber into the FP cavity, which provides real-time tuning to obtain the highest possible finesse up to 18.79. In volume refractive index measurement, a sensitivity of 960 nm per refractive index unit (RIU) and a detection range of 0.043 RIU are achieved.

A reconfigurable optofluidic Michelson interferometer using tunable droplet grating

This paper presents a novel optofluidic Michelson interferometer based on droplet microfluidics used to create a droplet grating. The droplet grating is formed by a stream of plugs in the microchannel with constant refractive index variation. It has a real-time tunability in the grating period through varying the flow rates of the liquids and index variation via different combinations of liquids. The optofluidic Michelson interferometer is highly sensitive and is suitable for the measurement of biomedical and biochemical buffer solutions. The experimental results show that it has a sensitivity of 66.7 nm per refractive index unit (RIU) and a detection range of 0.086 RIU.

The treatment of varicose veins: an investigation of patient preferences and expectations

Objectives

A number of modalities are now available for the treatment of varicose veins. The aim of the study was to investigate the factors considered important by patients when contemplating treatment of their varicose veins.

Methods

Consecutive new patients referred to a vascular surgery service were invited to complete a short anonymous questionnaire prior to their consultation. The questionnaire consisted of 13 multiple choice questions relating to symptoms, potential varicose vein treatments and patient knowledge of existing therapies.

Results

Of 111 patients, there were 83 complete responses (75%). Symptoms of pain or aching were reported as moderate or severe by 77/103 (75%) of patients and significantly limited the activities of 47/101 (47%). Although the majority (89/103 [86%]) of patients were aware of surgery, only 52/103 (51%) knew of the existence of endothermal ablation (either laser or radiofrequency) and only 23/103 (22%) were aware of foam sclerotherapy. Some 58/92 (63%) were in favour of local anaesthetic treatment. Most patients (74/103, 72%) felt inadequately informed to express a preference regarding treatment type prior to their consultation, although 24/103 (23%) expressed a preference for endovenous treatment. Interestingly, 74/92 (80%) stated that the opinion of their vascular surgeon would be likely to or definitely influence their treatment decision and the majority of patients stated that what they had read in magazines (54/80, 64%) or on the Internet (51/85, 60%) would have no influence on their decision regarding treatment, respectively.

Conclusion

Only a minority of patients referred with varicose veins were aware of endovenous treatments or felt adequately informed to express a treatment preference prior to consultation. Over half of patients expressed a preference for local anaesthetic therapy and a preference for a single visit treatment, although most would be strongly influenced by the opinion of their vascular surgeon and not influenced by media advertising.

Endovenous treatments for varicose veins – over-taking or over-rated?

Objectives

A variety of endovenous therapies for the treatment of superficial venous incompetence are currently available. The aim of this study was to evaluate the prevalence of endovenous techniques used by consultant vascular surgeons in the United Kingdom.

Methods

An anonymous online survey of 16 multiple choice questions relating to the nature and provision of treatment for varicose veins was devised. Consultant members of the Vascular Society of Great Britain and Ireland were invited to participate by email.

Results

A total of 108/352 (31%) surgeons completed the survey. The majority offered surgery as the first-line treatment for primary great saphenous vein (GSV) and small saphenous vein (SSV) incompetence (69% and 74%, respectively). Endovenous procedures were offered as first-line treatment by 32/108 (29.6%) for GSV reflux, 36/51 (70.6%) surgeons performed these under local anaesthetic and 21/51 (41.2%) were performed as an outpatient procedure. The most important factor influencing treatment decisions was considered to be patient preference by 77/108 (71.3%) surgeons, although 48/61 (78.7%) respondents were restricted by primary care trusts with regard to endovenous treatments, and 33/108 (30.6%) offered different treatments to private patients.

Conclusion

Traditional surgery remains the most commonly offered treatment for patients with varicose veins. The provision of endovenous therapies varies greatly, and there are significant differences in local availability regarding these treatments.

Pathogenesis of primary varicose veins

BACKGROUND

Valvular incompetence and reflux are common features of primary varicose veins, and have long been thought to be their cause. Recent evidence, however, suggests that changes in the vein wall may precede valvular dysfunction.

METHODS

A literature search was performed using PubMed and Ovid using the keywords 'varicose vein wall changes', 'pathogenesis', 'aetiology' and 'valvular dysfunction'. Articles discussing the pathophysiology of complications of varicose veins, such as ulceration, recurrence, thrombophlebitis and lipodermatosclerosis, were excluded.

RESULTS AND CONCLUSION

Positive family history, age, sex and pregnancy are important risk factors for varicose vein formation. Areas of intimal hyperplasia and smooth muscle cell proliferation are often noted in varicose veins, although regions of atrophy are also present. The total elastin content in varicose as opposed to non-varicose veins is reduced; changes in overall collagen content are uncertain. Matrix metalloproteinases (MMPs), including MMP-1, MMP-2, MMP-3, MMP-7 and MMP-9, and tissue inhibitor of metalloproteinase (TIMP) 1 and TIMP-3 are upregulated in varicose veins. Activation of the endothelium stimulates the recruitment of leucocytes and the release of growth factors, leading to smooth muscle cell proliferation and migration. Dysregulated apoptosis has also been demonstrated in varicose veins. An understanding of the pathophysiology of varicose veins is important in the identification of potential therapeutic targets and treatment strategies.

Microchip system for monitoring microbial physiological behaviour under drug influences

Single-step real-time high-throughput monitoring of drug influences on bacterial cell behaviour has become important with growing interests in personalized therapy and medication. Conventional microchip assemblies to perform similar work do exist. However, most of these devices have complex set-ups incorporating micromixers, separators, pumps, or valves. These microcomponents can sometimes damage the entities being monitored because of the creation of unfavourable biological environments. This paper presents a microchip-based system that enables single-step mixing of two solutions in various ratios, without the need for additional microcomponents such as mixers and pumps, in order to screen effectively their combinatory effects on cell outcomes. In this work, in-vitro experiments were carried out using ampicillin at various concentrations to investigate their effects on Escherichia coli (E. coli). Results showed that the microchip provided effective screening, which yielded useful results such as effective dosages, ineffective dosages, and other possible outcomes; for instance, in this case, the occurrence of adaptive mutation of the bacteria at certain drug concentrations. Comparative microbiological laboratory tests were carried out as standard for confirmation of the results.

Early-onset osteoarthritis of mouse temporomandibular joint induced by partial discectomy

OBJECTIVE

The objective of this study is to characterize mouse temporomandibular joint (TMJ) following partial discectomy, since there is no documentation of whether or not partial discectomy can induce early-onset osteoarthritis (OA) in mouse TMJ.

METHODS

Partial discs of TMJ in mice were removed by microsurgery. Histology was performed to characterize articular cartilages from the TMJ of mice. The morphology of the articular cartilages was evaluated using a modified Mankin scoring system. Immunohistostaining was carried out to examine the expression of discoidin domain receptor 2 (Ddr2), a type II collagen receptor, matrix metalloproteinase-13 (Mmp-13), and Mmp-derived type II collagen fragments in the articular cartilage of condyles from the mouse TMJ.

RESULTS

Articular cartilage degeneration was seen in the mouse TMJ post-discectomy, including increased proteoglycan staining in the extracellular matrix at 4 weeks, the appearance of chondrocyte clusters at 8 weeks, reduced proteoglycan staining and fibrillation at 12 weeks and the loss of articular cartilage at 16 weeks. Increased immunostaining for Ddr2, Mmp-13, and Mmp-derived type II collagen fragments was detected.

CONCLUSION

Results indicate that partial discectomy induces early-onset OA in mouse TMJ and that increased expression of Mmp-13, likely due to the elevated expression of Ddr2, may be one of the factors responsible for the early-onset OA in mouse TMJ.

Use of the pulse transit time trend to relate tidal breathing and central respiratory events

Central sleep apnoea (CSA) is a respiratory event where cessation of breathing effort and airflow occurs. Numerous lumped models have related the physical phenomena in the arterial tree to properties of the arterial wall. However, a limited model is available that describes pulse transit time (PTT) oscillations during CSA and tidal breathing. Data from 28 children (22 males; aged 6.2 +/- 3.6 years) were obtained during overnight polysomnography. Using a lumped-element model, PTT fluctuations during both respiratory events were described and compared with actual experimental data. 222 valid CSA and 222 tidal breathing events were acquired and analysed. For the tidal breathing, undamped PTT oscillations of 3.89 s were predicted while actual data showed a mean value of 3.68 +/- 0.83 s. Conversely, a damped PTT trend was observed during CSA as predicted by the model. The results attained showed that clustered CSA occurrences led to an increase of 7.23 +/- 3.34 per cent in PTT baseline value while the model predicted 7.86 +/- 2.63 per cent. The marginal increase in PTT baseline was expected since the blood pressure and heart rate decreased during such occurrences. The findings herein suggest that the described model has the potential to describe respiratory event characteristics of a sleeping child.

A simplified tumor regression grade correlates with survival in locally advanced rectal carcinoma treated with neoadjuvant chemoradiotherapy

BACKGROUND

Locally advanced rectal cancer is frequently treated with neoadjuvant chemoradiotherapy to reduce local recurrence and possibly improve survival. The tumor response to chemoradiotherapy is variable and may influence the prognosis after surgery. This study assessed tumor regression and its influence on survival in patients with rectal cancer treated with chemoradiotherapy followed by curative surgery.

METHODS

One hundred twenty-six patients with locally advanced rectal cancer (T3/T4 or N1/N2) were treated with chemoradiotherapy followed by total mesorectal excision. Patients received long-course radiotherapy (50 Gy in 25 fractions) in combination with 5-flourouracil over 5 weeks. By means of a standardized approach, tumor regression was graded in the resection specimen using a 3-point system related to tumor regression grade (TRG): complete or near-complete response (TRG1), partial response (TRG2), or no response (TRG3).

RESULTS

The 5-year disease-free survival was 72% (median follow-up 37 months), and 7% of patients had local recurrence. Chemoradiotherapy produced downstaging in 60% of patients; 21% of patients experienced TRG1. TRG1 correlated with a pathological T0/1 or N0 status. Five-year disease-free survival after chemoradiotherapy and surgery was significantly better in TRG1 patients (100%) compared with TRG2 (71%) and TRG3 (66%) (P = .01).

CONCLUSION

Tumor regression grade measured on a 3-point system predicts outcome after chemoradiotherapy and surgery for locally advanced rectal cancer.