Yue, Zhilian

Research Areas

0303 - MACROMOLECULAR AND MATERIALS CHEMISTRY

Research Overview

Research Interests:
- Functional Biomaterials
- Surface Bioengineering
- Tissue Engineering and Regenerative Medicine
- Nanomedicine
- Macroporous Hydrogels

Selected Publications

Journal Article

Year	Title
2021	FLASH: Fluorescently LAbelled Sensitive Hydrogel to monitor bioscaffolds degradation during neocartilage generation Published In Biomaterials
2020	3D Coaxial Printing Tough and Elastic Hydrogels for Tissue Engineering Using a Catechol Functionalized Ink System Published In Advanced Healthcare Materials
2020	3D hybrid printing platform for auricular cartilage reconstruction Published In Biomedical Physics and Engineering Express
2020	Bipolar electroactive conducting polymers for wireless cell stimulation Published In Applied Materials Today
2020	Composite Tissue Adhesive Containing Catechol-Modified Hyaluronic Acid and Poly- l -lysine Published In ACS Applied Bio Materials
2020	Design, Synthesis and Characterization of a Novel Type of Thermo-Responsible Phospholipid Microcapsule-Alginate Composite Hydrogel for Drug Delivery Published In Molecules
2020	Electrofluidic control of bioactive molecule delivery into soft tissue models based on gelatin methacryloyl hydrogels using threads and surgical sutures Published In Scientific Reports
2020	Encapsulation of Human Natural and Induced Regulatory T-Cells in IL-2 and CCL1 Supplemented Alginate-GelMA Hydrogel for 3D Bioprinting Published In Advanced Functional Materials
2020	Fabrication of Aligned Biomimetic Gellan Gum-Chitosan Microstructures through 3D Printed Microﬂuidic Channels and Multiple In Situ Cross-Linking Mechanisms Published In ACS Biomaterials Science and Engineering
2020	Free-form co-axial bioprinting of a gelatin methacryloyl bio-ink by direct in situ photo-crosslinking during extrusion Published In Bioprinting
2020	Nanoscale piezoelectric effect of biodegradable PLA-based composite fibers by piezoresponse force microscopy Published In Nanotechnology
2019	A simple technique for development of fibres with programmable microsphere concentration gradients for local protein delivery Published In Journal of Materials Chemistry B
2019	Development of a Coaxial 3D Printing Platform for Biofabrication of Implantable Islet-Containing Constructs Published In Advanced Healthcare Materials
2019	Development of rhamnose-rich hydrogels based on sulfated xylorhamno-uronic acid toward wound healing applications Published In Biomaterials Science
2019	Engineering of perfusable double-layered vascular structures using contraction of spheroid-embedded hydrogel and electrochemical cell detachment Published In Journal of Bioscience and Bioengineering
2019	On Low-Concentration Inks Formulated by Nanocellulose Assisted with Gelatin Methacrylate (GelMA) for 3D Printing toward Wound Healing Application Published In ACS Applied Materials and Interfaces
2019	Quantitative ultrasound imaging of cell-laden hydrogels and printed constructs Published In Acta Biomaterialia
2018	A bioprinting printing approach to regenerate cartilage for microtia treatment Published In Bioprinting
2018	A contactless approach for monitoring the mechanical properties of swollen hydrogels Published In Soft Matter
2018	Advanced fabrication approaches to controlled delivery systems for epilepsy treatment Published In Expert Opinion on Drug Delivery
2018	Fabrication and in vitro characterization of electrochemically compacted collagen/sulfated xylorhamnoglycuronan matrix for wound healing applications Published In Polymers
2018	In situ handheld three-dimensional bioprinting for cartilage regeneration Published In Journal of Tissue Engineering and Regenerative Medicine
2018	Magnetoelectric Coupling in Nanoscale 0-1 Connectivity Published In Nanoscale
2018	Nanocrystalline Cellulose for Anisotropic Magnetoelectric Composites Published In Macromolecular Materials and Engineering
2018	Three-Dimensional Printing and Cell Therapy for Wound Repair Published In Advances in Wound Care
2017	Cellulose- based magnetoelectric composites Published In Nature Communications
2017	Development of drug-loaded polymer microcapsules for treatment of epilepsy Published In Biomaterials Science
2017	Evaluation of the Biocompatibility of Polypyrrole Implanted Subdurally in GAERS Published In Macromolecular Bioscience
2017	Local probing of magnetoelectric properties of PVDF/Fe3O4 electrospun nanofibers by piezoresponse force microscopy Published In Nanotechnology
2017	Preparation, Characterization and Toxicological Analysis of Alginate-phospholipid Vesicle Composite Hydrogels Published In Chemical Journal of Chinese Universities
2017	Probe Sensor Using Nanostructured Multi-Walled Carbon Nanotube Yarn for Selective and Sensitive Detection of Dopamine Published In Sensors
2017	Progress in research of carrier systems for targeting and controlled release of anticancer drug Published In Chinese Journal of New Drugs
2017	Three-dimensional neuronal cell culture: in pursuit of novel treatments for neurodegenerative disease Published In MRS Communications
2016	3D bioprinting: Can we create the structures in living cells? Published In Australasian Biotechnology
2016	Advances in printing biomaterials and living cells: implications for islet cell transplantation Published In Current Opinion in Organ Transplantation
2016	Antiepileptic effects of lacosamide loaded polymers implanted subdurally in GAERS Published In International Journal of Polymer Science
2016	Conductive and protein resistant polypyrrole films for dexamethasone delivery Published In Journal of Materials Chemistry B
2016	Development and validation of a seizure initiated drug delivery system for the treatment of epilepsy Published In Sensors and Actuators B: Chemical: international journal devoted to research and development of physical and chemical transducers
2016	Development of the Biopen: a handheld device for surgical printing of adipose stem cells at a chondral wound site Published In Biofabrication
2015	A simple and versatile method for microencapsulation of anti-epileptic drugs for focal therapy of epilepsy Published In Journal of Materials Chemistry B
2015	Injectable phenytoin loaded polymeric microspheres for the control of temporal lobe epilepsy in rats Published In Restorative Neurology and Neuroscience
2014	Hydroxypropyl cellulose methacrylate as a photo-patternable and biodegradable hybrid paper substrate for cell culture and other bioapplications Published In Advanced Healthcare Materials
2014	Influence of biodopants on PEDOT biomaterial polymers: using QCM-D to characterize polymer interactions with proteins and living cells Published In Advanced Materials Interfaces
2013	Bio-ink properties and printability for extrusion printing living cells Published In Journal of Biomaterials Science: Polymer Edition
2013	Biofunctionalized anti-corrosive silane coatings for magnesium alloys Published In Acta Biomaterialia
2013	Controlled delivery for neuro-bionic devices Published In Advanced Drug Delivery Reviews
2013	Intrinsically stretchable supercapacitors composed of polypyrrole electrodes and highly stretchable gel electrolyte Published In ACS Applied Materials and Interfaces
2013	PEGylation of platinum bio-electrodes Published In Electrochemistry Communications
2013	Preparation of a soft and interconnected macroporous hydroxypropyl cellulose methacrylate scaffold for adipose tissue engineering Published In Journal of Materials Chemistry B
2013	Sensitive and selective dopamine determination in human serum with inkjet printed Nafion/MWCNT chips Published In Electrochemistry Communications
2013	Surface-functionalization of PDMS for potential micro-bioreactor and embryonic stem cell culture applications Published In Journal of Materials Chemistry B
2013	Thermoresponsive cellulosic hydrogels with cell-releasing behavior Published In ACS Applied Materials and Interfaces
2012	Organic conducting polymer-protein interactions Published In Chemistry of Materials
2011	Bio-functionalisation of polydimethylsiloxane with hyaluronic acid and hyaluronic acid - Collagen conjugate for neural interfacing Published In Biomaterials
2011	Buckled, stretchable polypyrrole electrodes for battery applications Published In Advanced Materials
2011	Conducting polymers with immobilised fibrillar collagen for enhanced neural interfacing Published In Biomaterials
2011	Galactosylated cellulosic sponge for multi-well drug safety testing Published In Biomaterials
2010	Control of in vitro neural differentiation of mesenchymal stem cells in 3D macroporous cellulosic hydrogels Published In Regenerative Medicine
2010	Preparation of three-dimensional interconnected macroporous cellulosic hydrogels for soft tissue engineering Published In Biomaterials
2010	Rapid construction of mechanically- confined multi-cellular structures using dendrimeric intercellular linker Published In Biomaterials
2009	Synthesis and pH-responsive properties of pseudo-peptide containing hydrophobic amino acid grafts Published In Journal of Materials Chemistry
2008	Aqueous solution behaviour and membrane disruptive activity of pH-responsive PEGylated pseudo-peptides and their intracellular distribution Published In Biomaterials
2008	Dendrimer hydrazides as multivalent transient inter-cellular linkers Published In Biomaterials
2008	Fluorescence and lifetime imaging of free and micellar-encapsulated doxorubicin in living cells Published In Nanomedicine: Nanotechnology, Biology and Medicine

Conference Paper

Year	Title
2009	Transdermal drug delivery: microfabrication insights Published In CAS 2009 Proceedings: 2009 International Semiconductor conference

Investigator On

Year	Title
2020 - 2021	Optimizing a preclinical model for bioprinting skin aimed at repairing skin loss in patients Awarded by: Medical Research Future Fund (MRFF) Funding Scheme: Stem Cell Therapies Mission Grant
2013 - 2016	Development of bifunctional anti-uPA/anti-HER-2 lipidic nanoparticles to target advanced breast cancer Awarded by: Cancer Australia Funding Scheme: Priority-driven Collaborative Cancer Research Scheme (PdCCRS)

Advisees

Graduate Advising Relationship

Degree	Research Title	Advisee
Doctor of Philosophy	3D Printing Biosynthetic Chondral Grafts
Doctor of Philosophy	3D Printing of Collagen Bioinks for Regenerative Medicine	Maher, Malachy
Doctor of Philosophy	3D Printed Porous Structures Based on Porestar with Hydroxyapatite Distributed Throughout	Dinoro, Jeremy
Doctor of Philosophy	Fabrication of ulvan based structure for skin tissue engineering and wound healing application	Chen, Xifang
Doctor of Philosophy	3D Printed Skin Grafts for Coverage of Partial or Full Thickness Burns	Daikuara, Luciana
Doctor of Philosophy	Development of Multifunctional Bioinks for 3D Printing Cellular Constructs	Zhou, Ying
Doctor of Philosophy	Bipolar Electroactive Conducting Polymers for Wireless Cell Stimulation	Qin, Chunyan
Doctor of Philosophy	Remotely Activated, Contactless Electrodes in Electrochemistry	Marks, Sulokshana
Doctor of Philosophy	Development of next generation Biopen to enable variable crosslinking density during printing.	Talaei, Alireza
Doctor of Philosophy	Conductive Hydrogel for Cardiovascular Tissue Engineering	Shoushtari Zadeh Naseri, Aida
Master of Philosophy	Hystent Project: 3D-printed cardiovascular stents. Customization of 3D printer and development of stents	Castaneda Garay, Diego
Doctor of Philosophy	Advanced fabrication techniques for silk fibroin based structures and uses thereof	Hai, Abdul Moqeet
Master of Philosophy -SMAH	Optimizing the bioinks for islet tissue engineering by using a customized co-axial bioprinter	Gantumur, Narangerel
Master of Philosophy -SMAH	3D printed and cell-laden structures for auricular cartilage growth	Haag, Hannah
Master of Philosophy -SMAH	3D Co-axial Bioprinting for Cartilage Repair and Regeneration	Bani, Jacopo
Master of Philosophy -SMAH	Bioink Formulation for Co-axial Extrusion Printing of Pancreatic Tissue Contructs	Urigoitia Asua, Ane
Doctor of Philosophy	Cellulose Reinforced Composites for Biomedical Applications	Azeem, Abdul
Doctor of Philosophy	Development of Vascularized Islet-Laden Constructs with 3D Bioprinting	Kulaga, Anna
Doctor of Philosophy	3D printing of innervated skin tissue for burn treatment	St Clair-Glover, Mitchell

Education And Training

B.Sc. in Polymer Chemistry, Hebei University
M.Sc. in Polymer Chemistry, Peking University
Ph.D., Heriot-Watt University

Located In Facility

Intelligent Polymer Research Institute

Research Areas

0303 - MACROMOLECULAR AND MATERIALS CHEMISTRY

Research Overview

Research Interests:
- Functional Biomaterials
- Surface Bioengineering
- Tissue Engineering and Regenerative Medicine
- Nanomedicine
- Macroporous Hydrogels

Selected Publications

Journal Article

Year	Title
2021	FLASH: Fluorescently LAbelled Sensitive Hydrogel to monitor bioscaffolds degradation during neocartilage generation Published In Biomaterials
2020	3D Coaxial Printing Tough and Elastic Hydrogels for Tissue Engineering Using a Catechol Functionalized Ink System Published In Advanced Healthcare Materials
2020	3D hybrid printing platform for auricular cartilage reconstruction Published In Biomedical Physics and Engineering Express
2020	Bipolar electroactive conducting polymers for wireless cell stimulation Published In Applied Materials Today
2020	Composite Tissue Adhesive Containing Catechol-Modified Hyaluronic Acid and Poly- l -lysine Published In ACS Applied Bio Materials
2020	Design, Synthesis and Characterization of a Novel Type of Thermo-Responsible Phospholipid Microcapsule-Alginate Composite Hydrogel for Drug Delivery Published In Molecules
2020	Electrofluidic control of bioactive molecule delivery into soft tissue models based on gelatin methacryloyl hydrogels using threads and surgical sutures Published In Scientific Reports
2020	Encapsulation of Human Natural and Induced Regulatory T-Cells in IL-2 and CCL1 Supplemented Alginate-GelMA Hydrogel for 3D Bioprinting Published In Advanced Functional Materials
2020	Fabrication of Aligned Biomimetic Gellan Gum-Chitosan Microstructures through 3D Printed Microﬂuidic Channels and Multiple In Situ Cross-Linking Mechanisms Published In ACS Biomaterials Science and Engineering
2020	Free-form co-axial bioprinting of a gelatin methacryloyl bio-ink by direct in situ photo-crosslinking during extrusion Published In Bioprinting
2020	Nanoscale piezoelectric effect of biodegradable PLA-based composite fibers by piezoresponse force microscopy Published In Nanotechnology
2019	A simple technique for development of fibres with programmable microsphere concentration gradients for local protein delivery Published In Journal of Materials Chemistry B
2019	Development of a Coaxial 3D Printing Platform for Biofabrication of Implantable Islet-Containing Constructs Published In Advanced Healthcare Materials
2019	Development of rhamnose-rich hydrogels based on sulfated xylorhamno-uronic acid toward wound healing applications Published In Biomaterials Science
2019	Engineering of perfusable double-layered vascular structures using contraction of spheroid-embedded hydrogel and electrochemical cell detachment Published In Journal of Bioscience and Bioengineering
2019	On Low-Concentration Inks Formulated by Nanocellulose Assisted with Gelatin Methacrylate (GelMA) for 3D Printing toward Wound Healing Application Published In ACS Applied Materials and Interfaces
2019	Quantitative ultrasound imaging of cell-laden hydrogels and printed constructs Published In Acta Biomaterialia
2018	A bioprinting printing approach to regenerate cartilage for microtia treatment Published In Bioprinting
2018	A contactless approach for monitoring the mechanical properties of swollen hydrogels Published In Soft Matter
2018	Advanced fabrication approaches to controlled delivery systems for epilepsy treatment Published In Expert Opinion on Drug Delivery
2018	Fabrication and in vitro characterization of electrochemically compacted collagen/sulfated xylorhamnoglycuronan matrix for wound healing applications Published In Polymers
2018	In situ handheld three-dimensional bioprinting for cartilage regeneration Published In Journal of Tissue Engineering and Regenerative Medicine
2018	Magnetoelectric Coupling in Nanoscale 0-1 Connectivity Published In Nanoscale
2018	Nanocrystalline Cellulose for Anisotropic Magnetoelectric Composites Published In Macromolecular Materials and Engineering
2018	Three-Dimensional Printing and Cell Therapy for Wound Repair Published In Advances in Wound Care
2017	Cellulose- based magnetoelectric composites Published In Nature Communications
2017	Development of drug-loaded polymer microcapsules for treatment of epilepsy Published In Biomaterials Science
2017	Evaluation of the Biocompatibility of Polypyrrole Implanted Subdurally in GAERS Published In Macromolecular Bioscience
2017	Local probing of magnetoelectric properties of PVDF/Fe3O4 electrospun nanofibers by piezoresponse force microscopy Published In Nanotechnology
2017	Preparation, Characterization and Toxicological Analysis of Alginate-phospholipid Vesicle Composite Hydrogels Published In Chemical Journal of Chinese Universities
2017	Probe Sensor Using Nanostructured Multi-Walled Carbon Nanotube Yarn for Selective and Sensitive Detection of Dopamine Published In Sensors
2017	Progress in research of carrier systems for targeting and controlled release of anticancer drug Published In Chinese Journal of New Drugs
2017	Three-dimensional neuronal cell culture: in pursuit of novel treatments for neurodegenerative disease Published In MRS Communications
2016	3D bioprinting: Can we create the structures in living cells? Published In Australasian Biotechnology
2016	Advances in printing biomaterials and living cells: implications for islet cell transplantation Published In Current Opinion in Organ Transplantation
2016	Antiepileptic effects of lacosamide loaded polymers implanted subdurally in GAERS Published In International Journal of Polymer Science
2016	Conductive and protein resistant polypyrrole films for dexamethasone delivery Published In Journal of Materials Chemistry B
2016	Development and validation of a seizure initiated drug delivery system for the treatment of epilepsy Published In Sensors and Actuators B: Chemical: international journal devoted to research and development of physical and chemical transducers
2016	Development of the Biopen: a handheld device for surgical printing of adipose stem cells at a chondral wound site Published In Biofabrication
2015	A simple and versatile method for microencapsulation of anti-epileptic drugs for focal therapy of epilepsy Published In Journal of Materials Chemistry B
2015	Injectable phenytoin loaded polymeric microspheres for the control of temporal lobe epilepsy in rats Published In Restorative Neurology and Neuroscience
2014	Hydroxypropyl cellulose methacrylate as a photo-patternable and biodegradable hybrid paper substrate for cell culture and other bioapplications Published In Advanced Healthcare Materials
2014	Influence of biodopants on PEDOT biomaterial polymers: using QCM-D to characterize polymer interactions with proteins and living cells Published In Advanced Materials Interfaces
2013	Bio-ink properties and printability for extrusion printing living cells Published In Journal of Biomaterials Science: Polymer Edition
2013	Biofunctionalized anti-corrosive silane coatings for magnesium alloys Published In Acta Biomaterialia
2013	Controlled delivery for neuro-bionic devices Published In Advanced Drug Delivery Reviews
2013	Intrinsically stretchable supercapacitors composed of polypyrrole electrodes and highly stretchable gel electrolyte Published In ACS Applied Materials and Interfaces
2013	PEGylation of platinum bio-electrodes Published In Electrochemistry Communications
2013	Preparation of a soft and interconnected macroporous hydroxypropyl cellulose methacrylate scaffold for adipose tissue engineering Published In Journal of Materials Chemistry B
2013	Sensitive and selective dopamine determination in human serum with inkjet printed Nafion/MWCNT chips Published In Electrochemistry Communications
2013	Surface-functionalization of PDMS for potential micro-bioreactor and embryonic stem cell culture applications Published In Journal of Materials Chemistry B
2013	Thermoresponsive cellulosic hydrogels with cell-releasing behavior Published In ACS Applied Materials and Interfaces
2012	Organic conducting polymer-protein interactions Published In Chemistry of Materials
2011	Bio-functionalisation of polydimethylsiloxane with hyaluronic acid and hyaluronic acid - Collagen conjugate for neural interfacing Published In Biomaterials
2011	Buckled, stretchable polypyrrole electrodes for battery applications Published In Advanced Materials
2011	Conducting polymers with immobilised fibrillar collagen for enhanced neural interfacing Published In Biomaterials
2011	Galactosylated cellulosic sponge for multi-well drug safety testing Published In Biomaterials
2010	Control of in vitro neural differentiation of mesenchymal stem cells in 3D macroporous cellulosic hydrogels Published In Regenerative Medicine
2010	Preparation of three-dimensional interconnected macroporous cellulosic hydrogels for soft tissue engineering Published In Biomaterials
2010	Rapid construction of mechanically- confined multi-cellular structures using dendrimeric intercellular linker Published In Biomaterials
2009	Synthesis and pH-responsive properties of pseudo-peptide containing hydrophobic amino acid grafts Published In Journal of Materials Chemistry
2008	Aqueous solution behaviour and membrane disruptive activity of pH-responsive PEGylated pseudo-peptides and their intracellular distribution Published In Biomaterials
2008	Dendrimer hydrazides as multivalent transient inter-cellular linkers Published In Biomaterials
2008	Fluorescence and lifetime imaging of free and micellar-encapsulated doxorubicin in living cells Published In Nanomedicine: Nanotechnology, Biology and Medicine

Conference Paper

Year	Title
2009	Transdermal drug delivery: microfabrication insights Published In CAS 2009 Proceedings: 2009 International Semiconductor conference

Investigator On

Year	Title
2020 - 2021	Optimizing a preclinical model for bioprinting skin aimed at repairing skin loss in patients Awarded by: Medical Research Future Fund (MRFF) Funding Scheme: Stem Cell Therapies Mission Grant
2013 - 2016	Development of bifunctional anti-uPA/anti-HER-2 lipidic nanoparticles to target advanced breast cancer Awarded by: Cancer Australia Funding Scheme: Priority-driven Collaborative Cancer Research Scheme (PdCCRS)

Advisees

Graduate Advising Relationship

Degree	Research Title	Advisee
Doctor of Philosophy	3D Printing Biosynthetic Chondral Grafts
Doctor of Philosophy	3D Printing of Collagen Bioinks for Regenerative Medicine	Maher, Malachy
Doctor of Philosophy	3D Printed Porous Structures Based on Porestar with Hydroxyapatite Distributed Throughout	Dinoro, Jeremy
Doctor of Philosophy	Fabrication of ulvan based structure for skin tissue engineering and wound healing application	Chen, Xifang
Doctor of Philosophy	3D Printed Skin Grafts for Coverage of Partial or Full Thickness Burns	Daikuara, Luciana
Doctor of Philosophy	Development of Multifunctional Bioinks for 3D Printing Cellular Constructs	Zhou, Ying
Doctor of Philosophy	Bipolar Electroactive Conducting Polymers for Wireless Cell Stimulation	Qin, Chunyan
Doctor of Philosophy	Remotely Activated, Contactless Electrodes in Electrochemistry	Marks, Sulokshana
Doctor of Philosophy	Development of next generation Biopen to enable variable crosslinking density during printing.	Talaei, Alireza
Doctor of Philosophy	Conductive Hydrogel for Cardiovascular Tissue Engineering	Shoushtari Zadeh Naseri, Aida
Master of Philosophy	Hystent Project: 3D-printed cardiovascular stents. Customization of 3D printer and development of stents	Castaneda Garay, Diego
Doctor of Philosophy	Advanced fabrication techniques for silk fibroin based structures and uses thereof	Hai, Abdul Moqeet
Master of Philosophy -SMAH	Optimizing the bioinks for islet tissue engineering by using a customized co-axial bioprinter	Gantumur, Narangerel
Master of Philosophy -SMAH	3D printed and cell-laden structures for auricular cartilage growth	Haag, Hannah
Master of Philosophy -SMAH	3D Co-axial Bioprinting for Cartilage Repair and Regeneration	Bani, Jacopo
Master of Philosophy -SMAH	Bioink Formulation for Co-axial Extrusion Printing of Pancreatic Tissue Contructs	Urigoitia Asua, Ane
Doctor of Philosophy	Cellulose Reinforced Composites for Biomedical Applications	Azeem, Abdul
Doctor of Philosophy	Development of Vascularized Islet-Laden Constructs with 3D Bioprinting	Kulaga, Anna
Doctor of Philosophy	3D printing of innervated skin tissue for burn treatment	St Clair-Glover, Mitchell

Education And Training

B.Sc. in Polymer Chemistry, Hebei University
M.Sc. in Polymer Chemistry, Peking University
Ph.D., Heriot-Watt University

Located In Facility

Intelligent Polymer Research Institute

Yue, Zhilian Senior Research Fellow

Faculty Member

Overview

Research Areas

Research Overview

Publications

Selected Publications

Journal Article

Conference Paper

Funding

Investigator On

Supervision

Advisees

Graduate Advising Relationship

Background

Education And Training

Contact

Located In Facility

Overview

Research Areas

Research Overview

Publications

Selected Publications

Journal Article

Conference Paper

Funding

Investigator On

Supervision

Advisees

Graduate Advising Relationship

Background

Education And Training

Contact

Located In Facility

Visualisations

Research Areas