Hybrid integrated thin-film lithium niobate-silicon nitride electro-optical phased array incorporating silicon nitride grating antenna for two-dimensional beam steering.

This study proposes a solid-state two-dimensional beam-steering device based on an electro-optical phased array (EOPA) in thin-film lithium niobate (TFLN) and silicon nitride (SiN) hybrid platforms, thereby eliminating the requirement for the direct etching of TFLN. Electro-optic (EO) phase modulator array comprises cascaded multimode interference couplers with an SiN strip-loaded TFLN configuration, which is designed and fabricated via i-line photolithography. Each EO modulator element with an interaction region length of 1.56 cm consumed a minimum power of 3.2 pJ/π under a half-wave voltage of 3.64 V and had an estimated modulation speed of 1.2 GHz. Subsequently, an SiN dispersive antenna with a waveguide grating was tethered to the modulator array to form an EOPA, facilitating the out-of-plane radiation of highly defined near-infrared beams. A prepared EOPA utilized EO phase control and wavelength tuning near 1550 nm to achieve a field-of-view of 22° × 5° in the horizontal and vertical directions. The proposed hybrid integrated platform can potentially facilitate low-power and high-speed beam steering.

Angularly offset multiline dispersive optical phased array enabling large field of view and plateau envelope.

We propose and demonstrate an angularly offset multiline (AOML) dispersive silicon nitride optical phased array (OPA) that enables efficient line beam scanning with an expanded field of view (FOV) and plateau envelope. The suggested AOML OPA incorporates multiline OPA units, which were seamlessly integrated with a 45° angular offset through a thermo-optic switch based on a multimode interference coupler, resulting in a wide FOV that combines three consecutive scanning ranges. Simultaneously, a periodic diffraction envelope rendered by the multiline OPA units contributes to reduced peak intensity fluctuation of the main lobe across the large FOV. An expedient polishing enabling the angled facet was diligently accomplished through the implementation of oblique polishing techniques applied to the 90° angle of the chip. For each dispersive OPA unit, we engineered an array of delay lines with progressively adjustable delay lengths, enabling a passive wavelength-tunable beam scanning. Experimental validation of the proposed OPA revealed efficient beam scanning, achieved by wavelength tuning from 1530 to 1600 nm and seamless switching between multiline OPAs, yielding an FOV of 152° with a main lobe intensity fluctuation of 2.8 dB. The measured efficiency of dispersive scanning was estimated at 0.97°/nm, as intended.

Association between colistin dose and development of nephrotoxicity.

OBJECTIVE: To investigate the development of nephrotoxicity associated with colistin dose, and whether this relationship differs depending on renal function. DESIGN: A retrospective cohort study of patients who received intravenous colistin to treat infections caused by extensively drug-resistant Gram-negative microorganisms. Adult patients receiving colistin for 72 hours or longer were included in this study. Patients who received renal replacement therapy at baseline or were administered colistin for less than 3 days were excluded. Colistin-induced nephrotoxicity was defined as a doubling of baseline serum creatinine. Colistin dosing was evaluated based on both actual body weight and ideal body weight. SETTING: Single general hospital between 2010 and 2013. PATIENTS: A total number of 475 patients received colistin therapy. Of these patients, 329 met the inclusion criteria and were included in the analysis. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred forty-three patients (43.5%) experienced nephrotoxicity during colistin treatment. The median onset time of nephrotoxicity was 6 days (interquartile range, 4-8 days). The patients with nephrotoxicity were older. Hematocrit and serum albumin levels were lower in patients with nephrotoxicity. Median daily dosing of colistin based on ideal body weight was significantly higher in patients with nephrotoxicity than in those without nephrotoxicity (4.55 vs 4.43 mg/kg/d, respectively; p=0.021). The cumulative dose was not different between patients with and without nephrotoxicity. In multiple logistic regression analysis, daily colistin dosing based on ideal body weight was only significantly associated with the development of nephrotoxicity in patients with an estimated glomerular filtration rate<60 mL/min/1.73 m2 (odds ratio, 2.34; 95% CI, 1.22-4.5). In these affected patients, based on a receiver operating characteristic plot, the optimal predictive cutoff of colistin dose for the development of nephrotoxicity was 2.87 mg/kg/d of colistin, with a sensitivity of 92.3% and a specificity of 76.7%. In patients with estimated glomerular filtration rate≥60 mL/min/1.73 m, age, serum albumin, hematocrit, and use of glycopeptide were associated with the development of nephrotoxicity. CONCLUSIONS: Development of nephrotoxicity was significantly more strongly associated with the dose of colistin, but only in patients with an estimated glomerular filtration rate<60 mL/min/1.73 m2 and not in those with normal renal function.

A framework for effective face-mask contact modeling based on finite element analysis for custom design of a facial mask.

A novel contact model is presented to efficiently solve a face-mask contact problem by using the finite element (FE) method for the optimized design of a custom facial mask. Simulation of contact pressure for various mask designs considering material properties of the face allows virtual evaluation of the suitability of a mask design for a person's face without conducting empirical measurement of the face-mask contact pressure. The proposed contact model is accomplished by combining three approaches to reduce the calculation cost of simulating the face-mask contact: (1) use of a simplified and modifiable mask model that applies a spline curve to design points; (2) reduction of the FE model of the face by applying static condensation; and (3) application of a contact assumption that uses the Lagrange multiplier method. A numerical case study of a medical mask design showed that the proposed model could calculate the face-mask contact pressure efficiently (0.0448 sec per design). In a pilot usability experiment, the measured contact pressure was found similar values (range of mean contact pressure: 0.0093 ~ 0.0150 MPa) to the estimated values (range of mean contact pressure: 0.0097 ~ 0.0116 MPa).