Imbibition of Femtoliter-Scale DNA-Rich Aqueous Droplets into Porous Nylon Substrates by Molecular Printing.

This work presents the first reported imbibition mechanism of femtoliter (fL)-scale droplets produced by microchannel cantilever spotting (µCS) of DNA molecular inks into porous substrates (hydrophilic nylon). Differently from macroscopic or picoliter droplets, the downscaling to the fL-size leads to an imbibition process controlled by the subtle interplay of evaporation, spreading, viscosity, and capillarity, with gravitational forces being quasi-negligible. In particular, the minimization of droplet evaporation, surface tension, and viscosity allows for a reproducible droplet imbibition process. The dwell time on the nylon surface permits further tuning of the droplet lateral size, in accord with liquid ink diffusion mechanisms. The functionality of the printed DNA molecules is demonstrated at different imbibed oligonucleotide concentrations by hybridization with a fluorolabeled complementary sequence, resulting in a homogeneous coverage of DNA within the imbibed droplet. This study represents a first step toward the µCS-enabled fabrication of DNA-based biosensors and microarrays into porous substrates.

Emerging switchable ultraviolet photoluminescence in dehydrated Zn/Al layered double hydroxide nanoplatelets.

Layered double hydroxides show intriguing physical and chemical properties arising by their intrinsic self-assembled stacking of molecular-thick 2D nanosheets, enhanced active surface area, hosting of guest species by intercalation and anion exchanging capabilities. Here, we report on the unprecedented emerging intense ultraviolet photoluminescence in Zn/Al layered double hydroxide high-aspect-ratio nanoplatelets, which we discovered to be fully activated by drying under vacuum condition and thermal desorption as well. Photoluminescence and its quenching were reproducibly switched by a dehydration-hydration process. Photoluminescence properties were comprehensively evaluated, such as temperature dependence of photoluminescence features and lifetime measurements. The role of 2D morphology and arrangement of hydroxide layers was demonstrated by evaluating the photoluminescence before and after exfoliation of a bulk phase synthetized by a coprecipitation method.

Monitoring few molecular binding events in scalable confined aqueous compartments by raster image correlation spectroscopy (CADRICS).

The assembly of scalable liquid compartments for binding assays in array formats constitutes a topic of fundamental importance in life sciences. This challenge can be addressed by mimicking the structure of cellular compartments with biological native conditions. Here, inkjet printing is employed to develop up to hundreds of picoliter aqueous droplet arrays stabilized by oil-confinement with mild surfactants (Tween-20). The aqueous environments constitute specialized compartments in which biomolecules may exploit their function and a wide range of molecular interactions can be quantitatively investigated. Raster Image Correlation Spectroscopy (RICS) is employed to monitor in each compartment a restricted range of dynamic intermolecular events demonstrated through protein-binding assays involving the biotin/streptavidin model system.

Sustained Attention in Auditory and Visual Monitoring Tasks: Evaluation of the Administration of a Rest Break or Exogenous Vibrotactile Signals.

OBJECTIVE: Performance and mental workload were observed for the administration of a rest break or exogenous vibrotactile signals in auditory and visual monitoring tasks. BACKGROUND: Sustained attention is mentally demanding. Techniques are required to improve observer performance in vigilance tasks. METHOD: Participants (N = 150) monitored an auditory or a visual display for changes in signal duration in a 40-min watch. During the watch, participants were administered a rest break or exogenous vibrotactile signals. RESULTS: Detection accuracy was significantly greater in the auditory than in the visual modality. A short rest break restored detection accuracy in both sensory modalities following deterioration in performance. Participants experienced significantly lower mental workload when monitoring auditory than visual signals, and a rest break significantly reduced mental workload in both sensory modalities. Exogenous vibrotactile signals had no beneficial effects on performance, or mental workload. CONCLUSION: A rest break can restore performance in auditory and visual vigilance tasks. Although sensory differences in vigilance tasks have been studied, this study is the initial effort to investigate the effects of a rest break countermeasure in both auditory and visual vigilance tasks, and it is also the initial effort to explore the effects of the intervention of a rest break on the perceived mental workload of auditory and visual vigilance tasks. Further research is warranted to determine exact characteristics of effective exogenous vibrotactile signals in vigilance tasks. APPLICATION: Potential applications of this research include procedures for decreasing the temporal decline in observer performance and the high mental workload imposed by vigilance tasks.

Hybrid, multiplexed, functional DNA nanotechnology for bioanalysis.

We herein aim to report on the fabrication of DNA nano-heterostructures usable as a robust multi-functional analytical system to obtain multiple and complex data in parallel format from a single sample with unprecedented analytical performances. The ability of chemical information contained in the sequences of programmed DNA structures to organize matter made DNA become a unique material in "the nanoworld". Such carefully designed DNA nanostructures can then be functionalized/templated with different biomolecules/nanomaterials as different as nanoparticles, nanowires, organic molecules, peptides, and proteins with controlled spacing on the nanometer scale (<10 nm). In this way, it is possible to combine the properties of both DNA and nanomaterials for exposing the designed functionality and customizable geometrical hetero-nanostructures. By coupling automated on-chip high yield DNA synthesis with low cost detection methods, DNA-nanotechnology can enable the realization of high-sensitivity, multiplexed bioanalytical assays for many different applications like diagnostics, drug screening, toxicology, immunology and biosensors.

Effects of talker sex and voice style of verbal cockpit warnings on performance.

OBJECTIVE: The effects of talker sex and voice style of verbal cockpit warnings on performance were investigated to help make warning messages distinct from speech on the flight deck. BACKGROUND: Auditory warnings are used in aircraft to alert the crew to hazards and their associated levels of danger. Failing to comply with a warning has led to aviation incidents and accidents. METHODS: Participants were required to monitor the auditory channel and identify the verbal warning while simultaneously performing a visual pursuit tracking task. A male and a female actor annunciated the warning words in three styles: monotone, urgent, and whisper. In Experiment 1, warning words were presented in quiet, and in Experiment 2, they were presented in a background of speech babble that simulated cockpit radio communication. RESULTS: Experiment 1 showed that the monotone and urgent styles resulted in the fastest identification response time (RT) regardless of the talker and listener's sex. Experiment 2 showed that the male talker annunciating in either the monotone or the urgent style resulted in the largest proportion correct and fastest identification RT regardless of the listener's sex. Both experiments showed effects of word semantics on performance. CONCLUSION: Effective use of speech parameters and word semantics can increase the saliency of verbal cockpit warnings. APPLICATION: Potential applications of this research include improving the attention-getting capability of an alerting system, which could lead to increased warning compliance, potentially resulting in fewer incidents and accidents.

Three-dimensional auditory display for enhancing detection of passive sonar signals.

OBJECTIVE: The viability of a three-dimensional (3-D) auditory display for improving signal detection of passive sonar signals was investigated. BACKGROUND: Sonar operators usually have difficulty detecting targets because the sound received by the hydrophone has a low signal-to-noise ratio when coupled with the operator's headset that does not isolate well against the ambient noise. METHODS: Release from masking was assessed by pairing a recording of a torpedo with diotic broadband pink noise that served as a masker, and a 400 Hz tone with the masker. Masked thresholds were measured for seven signal durations when each signal was presented dioticly and in 3-D auditory space at three positions on the horizontal plane. RESULTS: The spatial separation of signal and masker yielded a significant improvement in detection. CONCLUSION: A 3-D auditory display is a viable technology that could lead to a significant improvement in release from masking. The magnitude of the masking level difference will vary with respect to the characteristics of the hydrophone signal and masker and the synthesis capability of the 3-D auditory display. APPLICATION: Potential applications of this research include enhanced auditory displays for processing passive sonar signals, leading to earlier detection of enemy targets.

Judging the urgency of non-verbal auditory alarms: a case study.

When designed correctly, non-verbal auditory alarms can convey different levels of urgency to the aircrew, and thereby permit the operator to establish the appropriate level of priority to address the alarmed condition. The conveyed level of urgency of five non-verbal auditory alarms presently used in the Canadian Forces CH-146 Griffon helicopter was investigated. Pilots of the CH-146 Griffon helicopter and non-pilots rated the perceived urgency of the signals using a rating scale. The pilots also ranked the urgency of the alarms in a post-experiment questionnaire to reflect their assessment of the actual situation that triggers the alarms. The results of this investigation revealed that participants' ratings of perceived urgency appear to be based on the acoustic properties of the alarms which are known to affect the listener's perceived level of urgency. Although for 28% of the pilots the mapping of perceived urgency to the urgency of their perception of the triggering situation was statistically significant for three of the five alarms, the overall data suggest that the triggering situations are not adequately conveyed by the acoustic parameters inherent in the alarms. The pilots' judgement of the triggering situation was intended as a means of evaluating the reliability of the alerting system. These data will subsequently be discussed with respect to proposed enhancements in alerting systems as it relates to addressing the problem of phase of flight. These results call for more serious consideration of incorporating situational awareness in the design and assignment of auditory alarms in aircraft.

The relative impact of generic head-related transfer functions on auditory speech thresholds: implications for the design of three-dimensional audio displays.

BACKGROUND: Auditory speech thresholds were measured in this study. METHODS: Subjects were required to discriminate a female voice recording of three-digit numbers in the presence of diotic speech babble. The voice stimulus was spatialized at 11 static azimuth positions on the horizontal plane using three different head-related transfer functions (HRTFs) measured on individuals who did not participate in this study. The diotic presentation of the voice stimulus served as the control condition. RESULTS: The results showed that two of the HRTFS performed similarly and had significantly lower auditory speech thresholds than the third HRTF. All three HRTFs yielded significantly lower auditory speech thresholds compared with the diotic presentation of the voice stimulus, with the largest difference at 60 degrees azimuth. CONCLUSION: The practical implications of these results suggest that lower headphone levels of the communication system in military aircraft can be achieved without sacrificing intelligibility, thereby lessening the risk of hearing loss.

Release from masking in virtual auditory space during sustained positive acceleration.

BACKGROUND: The use of a three-dimensional (3-D) auditory display to significantly lower subject detection level while maintaining comprehension under sustained positive G-stress was explored in this study. METHODS: Auditory threshold levels were measured for detecting a band limited pulsed signal in the presence of a broadband diotic masker at both + 1 Gz (rest position) and under sustained +3 Gz. The pulsed signal was presented diotically and was spatialized at one of four static azimuth positions on the horizontal plane. RESULTS: Results showed that auditory thresholds were not significantly affected by sustained +3 Gz stress. Compared with a diotic presentation, subjects reached an average of 6.8 dB lower auditory threshold at +1 Gz and under sustained +3 Gz when the pulsed signal was spatialized at a static position of 90 degrees azimuth on the horizontal plane. CONCLUSION: The implication of these results and suggestions for further research are discussed.

Dehiscence of intestinal anastomoses and anaesthesia.

This study, carried out in 62 patients undergoing surgery under general anaesthesia, has evaluated the nestigmine effects on tone and motility of the muscular rectal wall, by recording compliance and manometric values. An increase of intrarectal pressure values in patients antagonized with neostigmine has been evidenced. This finding is related to contracture and increased motility of muscular rectal wall, induced by anticholinesterase agent. In patients eligible for intestinal anastomoses, rapidly eliminated myoneural blocker such as atracurium besylate or vecuronium, should be preferred. These agents allow a spontaneous reversal of the myoneural block, without pharmacologic antagonism.

Polyps of the colon in juvenile and young patients: histological type and C.E.A. content in relation to follow-up.

31 colonic polyps in 21 patients between 2 and 30 years of age removed by endoscopy were studied. The site, size, cytohistological characteristic and tissue CEA content of these polyps were evaluated. 58% of the polyps were located in the rectum and sigmoid, the remaining 42% were in the descending colon. At histological examination 13 polyps proved to be neoplastic, 3 of which had severe dysplasia. In 3 cases of juvenile hyperplastic hamartomatous polyps and in 5 cases of inflammatory polyps the tissue C.E.A. was low; in 13 neoplastic polyps it was in direct correlation with the degree of dysplasia. Moreover in 10 patients with neoplastic polyps, 5 presented further adenomas at follow-up, and in 3 of them the C.E.A. tissue content of the first polyps obtained was medium to high. The occurrence in young patients of polyps of the colon with C.E.A. content medium to high must be followed by endoscopic examination at close intervals.

Nuclear steroid receptors and dysplasia in adenomatous polyps of the colon as markers of high risk for malignant transformation.

To detect an early colon carcinoma in its stage of carcinoma in situ, colonoscopic examinations with removal of all adenomas of the left colon (particularly of the sigmoid tract and rectum), followed by histological and biochemical evaluations, have been performed on 30 patients. Two-thirds of the adenomas examined presented histological patterns of tubular, tubulovillous, and villous adenomas; those with moderate or severe dysplasia were at high risk of neoplastic transformation. Measurement of estradiol (ER) and progesterone (PR) receptors was performed in the cytosol and in the nuclei of solitary and multiple adenomas and in those with synchronous carcinomas using the dextran-coated-charcoal (DCC) method. Steroid receptors were usually found in the cytosol of the large polyps of male rather than female patients (46% vs 11%) and in the cytosol of the adenomas with moderate or severe dysplasia in male patients. Malignant lesions usually possessed both ER and PR in the cytosol and nuclear fraction. These findings led to hypothesize that patients with adenomas of the colorectal tract with moderate or severe dysplasia and nuclear steroid receptors should be considered at high risk for colon carcinoma and therefore need a special follow-up program.