Severity: Warning
Message: file_get_contents(https://...@gmail.com&api_key=61f08fa0b96a73de8c900d749fcb997acc09): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 143
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 143
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 209
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3098
Function: getPubMedXML
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Severity: Warning
Message: Attempt to read property "Count" on bool
Filename: helpers/my_audit_helper.php
Line Number: 3100
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3100
Function: _error_handler
File: /var/www/html/application/controllers/Detail.php
Line: 574
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 488
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
Bubble crystals in water are expected to achieve the broad and low-frequency acoustic band gaps that are crucial for acoustic blocking. However, preparing patterned bubble crystals in water remains a challenge because of the instability of bubbly liquids. Here, inspired by biological superhydrophobic systems, we report a simple and rapid approach to prepare patterned bubble arrays in water and their applications in low-frequency acoustic blocking. Patterned bubbles with the desired size, shape, and position can be prepared. Single-layer bubble arrays can block the sounds at low frequencies because of local resonance. By varying the size and distance of the bubbles without changing the thickness, the operating frequency can change from 9 to 1756 kHz. Besides, by preparing multilayer bubbles, broad and low-frequency acoustic band gaps can be achieved, with the generalized width of γ (ratio of the bandgap width to its start frequency) reaching 1.26. This method provides a feasible strategy to control acoustic waves at low frequencies for applications such as acoustic blocking, focusing, imaging, and detecting.
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Source |
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http://dx.doi.org/10.1021/acsami.9b15683 | DOI Listing |
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