Sub-ppm Methane Detection with Mid-Infrared Slot Waveguides.

Hybrid integration of photonic chips with electronic and micromechanical circuits is projected to bring about miniature, but still highly accurate and reliable, laser spectroscopic sensors for both climate research and industrial applications. However, the sensitivity of chip-scale devices has been limited by immature and lossy photonic waveguides, weak light-analyte interaction, and etalon effects from chip facets and defects. Addressing these challenges, we present a nanophotonic waveguide for methane detection at 3270.4 nm delivering a limit of detection of 0.3 ppm, over 2 orders of magnitude lower than the state-of-the-art of on-chip spectroscopy. We achieved this result with a Si slot waveguide designed to maximize the light-analyte interaction, while special double-tip fork couplers at waveguide facets suppress spurious etalon fringes. We also study and discuss the effect of adsorbed humidity on the performance of mid-infrared waveguides around 3 µm, which has been repeatedly overlooked in previous reports.

A Complex Evaluation of the In-Vivo Biocompatibility and Degradation of an Extruded ZnMgSr Absorbable Alloy Implanted into Rabbit Bones for 360 Days.

The increasing incidence of trauma in medicine brings with it new demands on the materials used for the surgical treatment of bone fractures. Titanium, its alloys, and steel are used worldwide in the treatment of skeletal injuries. These metallic materials, although inert, are often removed after the injured bone has healed. The second-stage procedure-the removal of the plates and screws-can overwhelm patients and overload healthcare systems. The development of suitable absorbable metallic materials would help us to overcome these issues. In this experimental study, we analyzed an extruded Zn-0.8Mg-0.2Sr (wt.%) alloy on a rabbit model. From this alloy we developed screws which were implanted into the rabbit tibia. After 120, 240, and 360 days, we tested the toxicity at the site of implantation and also within the vital organs: the liver, kidneys, and brain. The results were compared with a control group, implanted with a Ti-based screw and sacrificed after 360 days. The samples were analyzed using X-ray, micro-CT, and a scanning electron microscope. Chemical analysis revealed only small concentrations of zinc, strontium, and magnesium in the liver, kidneys, and brain. Histologically, the alloy was verified to possess very good biocompatibility after 360 days, without any signs of toxicity at the site of implantation. We did not observe raised levels of Sr, Zn, or Mg in any of the vital organs when compared with the Ti group at 360 days. The material was found to slowly degrade in vivo, forming solid corrosion products on its surface.

Extraordinary evanescent field confinement waveguide sensor for mid-infrared trace gas spectroscopy.

Nanophotonic waveguides are at the core of a great variety of optical sensors. These structures confine light along defined paths on photonic chips and provide light-matter interaction via an evanescent field. However, waveguides still lag behind free-space optics for sensitivity-critical applications such as trace gas detection. Short optical pathlengths, low interaction strengths, and spurious etalon fringes in spectral transmission are among the main reasons why on-chip gas sensing is still in its infancy. In this work, we report on a mid-infrared integrated waveguide sensor that successfully addresses these drawbacks. This sensor operates with a 107% evanescent field confinement factor in air, which not only matches but also outperforms free-space beams in terms of the per-length optical interaction. Furthermore, negligible facet reflections result in a flat spectral background and record-low absorbance noise that can finally compete with free-space spectroscopy. The sensor performance was validated at 2.566 µm, which showed a 7 ppm detection limit for acetylene with only a 2 cm long waveguide.

Phenotypic characterization of oral mucosa: what is normal?

BACKGROUND: Knowledge of the phenotypic pattern of oral squamous epithelium is important in the histopathologic evaluation of lesions including cancer. The literature on normal epithelium is controversial as the phenotype has not been evaluated in samples from completely healthy tissue donors without a history of tobacco and alcohol exposure. METHODS: In this study, we evaluated normal upper lip fornix and gingival mucosa from carefully selected young healthy donors without a history of smoking and alcohol exposure, and keratin types 8, 10, 14, and 17, filaggrin, and Ki67 were investigated in these donors. The results were compared with profile of epithelium from leukoplakia. RESULTS: The results demonstrated that the phenotypic patterns of gingiva and upper lip fornix mucosa were different. Surprisingly, a high proportion of gingival samples exhibited keratin 8 and a suprabasal signal for keratin 14. These patterns were compared with that of human oral leukoplakia, and some phenotypic similarities were noted. CONCLUSIONS: These results demonstrated oral epithelium phenotypic plasticity based on functional requirements of the microenvironment, which can be used in diagnosis.

Fractional carbon dioxide laser improves nodular basal cell carcinoma treatment with photodynamic therapy with methyl 5-aminolevulinate.

BACKGROUND: The major limitation of photodynamic therapy with 5-aminolevulinic acid (ALA-PDT) is proper photosensitizer penetration. The nodular form of BCC (nBCC) is perceived as a contraindication to ALA-PDT because the tumor layer is thicker than 2 mm. We have improved on the results of previous studies that used an ablative laser to limit tumor thickness. A fractional laser produces skin microtubules that can improve the penetration of ALA into tumors. OBJECTIVE: To evaluate the use of a fractional laser as pretreatment before ALA-PDT for nBCC treatment in an 18-month single-blind clinical trial. METHODS: Fifty-six verified nBCCs were ablated using a diode laser under ultrasound control. Half of the tumors were treated 3 weeks later using a fractional carbon dioxide laser, and the other half were treated using curettage (control). We then immediately treated with ALA-PDT. Fluorescence and photography were evaluated and compared each month, and a final histopathologic examination was performed. RESULTS: Fifty-two of 56 nBCCs in the fractional laser treatment group responded to ALA-PDT, compared with only 45 of 56 in the control group. Fluorescence was higher in 53 cases in the treatment group; 3 cases demonstrated the same fluorescence level in both groups. Healing took longer in the treatment group, and there were more side effects. CONCLUSION: Fractional laser pretreatment increases the fluorescence and clinical effectiveness of ALA-PDT for the treatment of nBCC.

Ultrasound guided ablative-laser assisted photodynamic therapy of basal cell carcinoma (US-aL-PDT).

OBJECTIVE: With proper noninvasive ultrasound measurement of tumor depth, case selection for laser pre-ablation followed by PDT is possible. This combination of methods provides a less invasive approach to the treatment of BCC. BACKGROUND DATA: Basal cell carcinoma (BCC) primarily affects the face, and, therefore, radical excision is problematic because of the possibility of poor aesthetic outcomes. Photodynamic therapy (PDT) offers an advantage in aesthetic outcomes, but topical PDT is only effective for tumors with a depth up to 2 mm. MATERIALS AND METHODS: Seventy-five histologically verified BCCs from 67 patients were selected and divided into three therapeutic groups based on the tumor depth, which was determined by 20 MHz skin ultrasound. The three groups were: A/<2 mm (PDT), B/ 2-3 mm (Er:YAG laser ablation+PDT), and C/>3 mm (diode laser ablation+PDT). The treatment consisted of laser ablation (or no ablation) followed by the application of methyl-aminolevulinate (MAL) and a 3-h treatment period using an occlusive bandage. Subsequently, illumination with 630 nm (MAL-PDT) was performed. MAL-PDT was repeated 1-3 weeks after the first treatment. A clinical evaluation was performed after 6 months. RESULTS: A 100% clearance rate (CR) in the group with the deepest tumors was observed. In addition, a 94.7% CR occurred in the group with tumors 2-3 mm in depth, and an 81.2% CR was observed in the group with superficial tumors. CONCLUSIONS: With proper ultrasound case selection and laser ablation before MAL-PDT, the depth of a BCC lesion is not a limiting factor for PDT, and aesthetic outcomes are very good. Therefore, ultrasound-guided ablative laser-assisted PDT of BCC can be the method of choice, particularly in aesthetically challenging cases.

Combination of Er:YAG laser and photodynamic therapy in the treatment of nodular basal cell carcinoma.

BACKGROUNDS AND OBJECTIVES: Photodynamic therapy (PDT), via topical aminolevulinic acid (ALA) is an effective treatment for basal cell carcinomas not exceeding a depth of 2 mm. This limits the treatment of basal cell carcinoma (non-melanoma skin cancer) to superficial forms and nodular therapy (only in aesthetically desired locations). This paper addresses the effectiveness of reducing tumor mass via initial Er:YAG laser ablation to depths that are therapeutically responsive to PDT with ALA. STUDY DESIGN/MATERIALS AND METHODS: This study compared three methods for the treatment of recurring nodular basal cell carcinomas (r nBCC). Method A utilized PDT with topical application of ALA methyl ester, method B with solitary Er:YAG laser ablation, and method C combined Er:YAG laser ablation reducing tumor size below 2 mm (method B) with subsequent ALA methyl ester PDT (method A). All three methods were used to treat to each patient, all subjects presenting with three or more basal cell carcinomas in order to eliminate differences in patient responsiveness to treatment. Patients were monitored and interviewed at 3, 6, and 12 month intervals to examine the progress of tumor elimination, aesthetic results as well as the patient's preference of treatment method. In all, 286 patients were treated, of whom 194 were checked at the prescribed intervals and then evaluated. RESULTS: Statistically, the combination therapy demonstrated the most effective treatment at all time intervals, with a final efficacy of 98.97% versus 94.85% (PDT only) and 91.75% (Er:YAG laser only). The combined method also provided the best aesthetic results (scale: 1--best; 4--worst) of 1.23+/-1.23, compared to 1.67+/-0.76 (PDT only) and 1.83+/-0.95 (Er:YAG laser only). CONCLUSIONS: Although 67% patients preferred solitary Er:YAG laser treatment over the PDT method (20%) and the combined treatment (13%), because of the simplicity of the treatment, the combination therapy has proven to be both clinically and aesthetically superior. Solitary Er:YAG laser ablation will remain however a fast, effective, and economical treatment alternative for simple manifestations of superficial basal cell carcinoma and has replaced PDT for uncomplicated cases at our facility. The combination of Er:YAG laser ablation and ALA-PDT aspires to be therapy of choice for BCC.

Genioglossus advancement and hyoid myotomy in treating obstructive sleep apnoea syndrome - A follow-up study.

AIM: To assess the success of genioglossus advancement and hyoid myotomy in the obstructive sleep apnoea syndrome (OSAS) therapy by comparing pre- and postoperative respiratory values during sleep. One of the surgical methods of widening the upper airways is to advance the spina mandibulae together with the genioglossus insertion. Thus the whole tongue is advanced, including its base. Hyoid myotomy itself, leads to a very unaesthetic filling up of soft tissues in the submental space. Therefore, the original window method of genioglossus advancement was modified and the so-called tenon and mortise genioplasty according to Delaire was applied. PATIENTS AND METHODS: Thirty-one patients underwent genioglossus advancement by the modified genioplasty with hyoid myotomy (8 women and 23 men, mean age 53.2 years; range 35-69 years). Basic polysomnographic parameters were monitored (during sleep) before surgery and 7.3 months (range 3-6 months) postoperatively. RESULTS: The cumulative success rate was 74%. Subjective assessment of daily sleepiness using the Epworth scale dropped from preoperative 9.6 to 4.7. The average respiratory disturbance index decreased from 20.9 preoperatively to 10.3, the oxygen desaturation index dropped from 15.1 to 8.8, the average preoperative values of baseline oxygen saturation and average desaturation values had been 95.1% and 86.5%, respectively, and had increased postoperatively to 96.0% and 90.3%, respectively. On the average, preoperative desaturation lasted 36.7s whereas it lasted for 31.0 s postoperatively. CONCLUSION: Polysomonographic monitoring proved that changing the upper airways can favourably impact upon respiratory parameters during sleep in OSAS.